* Re: [RFC PATCH v2 13/27] mm: Handle shadow stack page fault
From: Dave Hansen @ 2018-07-10 23:06 UTC (permalink / raw)
To: Yu-cheng Yu, x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar,
linux-kernel, linux-doc, linux-mm, linux-arch, linux-api,
Arnd Bergmann, Andy Lutomirski, Balbir Singh, Cyrill Gorcunov,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek,
Peter Zijlstra <pet>
In-Reply-To: <20180710222639.8241-14-yu-cheng.yu@intel.com>
On 07/10/2018 03:26 PM, Yu-cheng Yu wrote:
> + if (is_shstk_mapping(vma->vm_flags))
> + entry = pte_mkdirty_shstk(entry);
> + else
> + entry = pte_mkdirty(entry);
> +
> + entry = maybe_mkwrite(entry, vma);
> if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
> update_mmu_cache(vma, vmf->address, vmf->pte);
> pte_unmap_unlock(vmf->pte, vmf->ptl);
> @@ -2526,7 +2532,11 @@ static int wp_page_copy(struct vm_fault *vmf)
> }
> flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
> entry = mk_pte(new_page, vma->vm_page_prot);
> - entry = maybe_mkwrite(pte_mkdirty(entry), vma);
> + if (is_shstk_mapping(vma->vm_flags))
> + entry = pte_mkdirty_shstk(entry);
> + else
> + entry = pte_mkdirty(entry);
> + entry = maybe_mkwrite(entry, vma);
Do we want to lift this hunk of code and put it elsewhere? Maybe:
entry = pte_set_vma_features(entry, vma);
and then:
pte_t pte_set_vma_features(pte_t entry, struct vm_area_struct)
{
/*
* Shadow stack PTEs are always dirty and always
* writable. They have a different encoding for
* this than normal PTEs, though.
*/
if (is_shstk_mapping(vma->vm_flags))
entry = pte_mkdirty_shstk(entry);
else
entry = pte_mkdirty(entry);
entry = maybe_mkwrite(entry, vma);
return entry;
}
> /*
> * Clear the pte entry and flush it first, before updating the
> * pte with the new entry. This will avoid a race condition
> @@ -3201,6 +3211,14 @@ static int do_anonymous_page(struct vm_fault *vmf)
> mem_cgroup_commit_charge(page, memcg, false, false);
> lru_cache_add_active_or_unevictable(page, vma);
> setpte:
> + /*
> + * If this is within a shadow stack mapping, mark
> + * the PTE dirty. We don't use pte_mkdirty(),
> + * because the PTE must have _PAGE_DIRTY_HW set.
> + */
> + if (is_shstk_mapping(vma->vm_flags))
> + entry = pte_mkdirty_shstk(entry);
> +
> set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
I'm not sure this is the right spot to do this.
The other code does pte_mkdirty_shstk() near where we do the
pte_mkwrite(). Why not here? I think you might have picked this
because it's a common path used by both allocated pages and zero pages.
But, we can't have the zero pages in shadow stack areas since they can't
be read-only. I think you need to move this up. Can you even
consolidate it with the other two pte_mkdirt_shstk() call sites?
> /* No need to invalidate - it was non-present before */
> @@ -3983,6 +4001,14 @@ static int handle_pte_fault(struct vm_fault *vmf)
> entry = vmf->orig_pte;
> if (unlikely(!pte_same(*vmf->pte, entry)))
> goto unlock;
> +
> + /*
> + * Shadow stack PTEs are copy-on-access, so do_wp_page()
> + * handling on them no matter if we have write fault or not.
> + */
I'd say this differently:
Shadow stack PTEs can not be read-only and because of that can
not have traditional copy-on-write semantics. This essentially
performs a copy-on-write operation, but on *any* access, not
just actual writes.
^ permalink raw reply
* [MANPAGE PATCH] Add manpage for fsinfo(2)
From: David Howells @ 2018-07-10 22:55 UTC (permalink / raw)
To: Michael Kerrisk
Cc: dhowells, viro, linux-api, linux-fsdevel, torvalds, linux-kernel,
linux-man
In-Reply-To: <153126269451.14533.13592791373864325188.stgit@warthog.procyon.org.uk>
Add a manual page to document the fsinfo() system call.
Signed-off-by: David Howells <dhowells@redhat.com>
---
man2/fsinfo.2 | 1017 +++++++++++++++++++++++++++++++++++++++++++++++++++
man2/ioctl_iflags.2 | 6
man2/stat.2 | 7
man2/statx.2 | 13 +
man2/utime.2 | 7
man2/utimensat.2 | 7
6 files changed, 1057 insertions(+)
create mode 100644 man2/fsinfo.2
diff --git a/man2/fsinfo.2 b/man2/fsinfo.2
new file mode 100644
index 000000000..5710232df
--- /dev/null
+++ b/man2/fsinfo.2
@@ -0,0 +1,1017 @@
+'\" t
+.\" Copyright (c) 2018 David Howells <dhowells@redhat.com>
+.\"
+.\" %%%LICENSE_START(VERBATIM)
+.\" Permission is granted to make and distribute verbatim copies of this
+.\" manual provided the copyright notice and this permission notice are
+.\" preserved on all copies.
+.\"
+.\" Permission is granted to copy and distribute modified versions of this
+.\" manual under the conditions for verbatim copying, provided that the
+.\" entire resulting derived work is distributed under the terms of a
+.\" permission notice identical to this one.
+.\"
+.\" Since the Linux kernel and libraries are constantly changing, this
+.\" manual page may be incorrect or out-of-date. The author(s) assume no
+.\" responsibility for errors or omissions, or for damages resulting from
+.\" the use of the information contained herein. The author(s) may not
+.\" have taken the same level of care in the production of this manual,
+.\" which is licensed free of charge, as they might when working
+.\" professionally.
+.\"
+.\" Formatted or processed versions of this manual, if unaccompanied by
+.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
+.\"
+.TH FSINFO 2 2018-06-06 "Linux" "Linux Programmer's Manual"
+.SH NAME
+fsinfo \- Get filesystem information
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.br
+.B #include <sys/fsinfo.h>
+.br
+.B #include <unistd.h>
+.br
+.BR "#include <fcntl.h> " "/* Definition of AT_* constants */"
+.PP
+.BI "int fsinfo(int " dirfd ", const char *" pathname ","
+.BI " struct fsinfo_params *" params ","
+.BI " void *" buffer ", size_t " buf_size );
+.fi
+.PP
+.IR Note :
+There is no glibc wrapper for
+.BR fsinfo ();
+see NOTES.
+.SH DESCRIPTION
+.PP
+fsinfo() retrieves the desired filesystem attribute, as selected by the
+parameters pointed to by
+.IR params ,
+and stores its value in the buffer pointed to by
+.IR buffer .
+.PP
+The parameter structure is optional, defaulting to all the parameters being 0
+if the pointer is NULL. The structure looks like the following:
+.PP
+.in +4n
+.nf
+struct fsinfo_params {
+ __u32 at_flags; /* AT_SYMLINK_NOFOLLOW and similar flags */
+ __u32 request; /* Requested attribute */
+ __u32 Nth; /* Instance of attribute */
+ __u32 Mth; /* Subinstance of Nth instance */
+ __u32 __reserved[6]; /* Reserved params; all must be 0 */
+};
+.fi
+.in
+.PP
+The filesystem to be queried is looked up using a combination of
+.IR dfd ", " pathname " and " params->at_flags.
+This is discussed in more detail below.
+.PP
+The desired attribute is indicated by
+.IR params->request .
+If
+.I params
+is NULL, this will default to
+.BR fsinfo_attr_statfs ,
+which retrieves some of the information returned by
+.BR statfs ().
+The available attributes are described below in the "THE ATTRIBUTES" section.
+.PP
+Some attributes can have multiple values and some can even have multiple
+instances with multiple values. For example, a network filesystem might use
+multiple servers. The names of each of these servers can be retrieved by
+using
+.I params->Nth
+to iterate through all the instances until error
+.B ENODATA
+occurs, indicating the end of the list. Further, each server might have
+multiple addresses available; these can be enumerated using
+.I params->Nth
+to iterate the servers and
+.I params->Mth
+to iterate the addresses of the Nth server.
+.PP
+The amount of data written into the buffer depends on the attribute selected.
+Some attributes return variable-length strings and some return fixed-size
+structures. If either
+.IR buffer " is NULL or " buf_size " is 0"
+then the size of the attribute value will be returned and nothing will be
+written into the buffer.
+.PP
+The
+.I params->__reserved
+parameters must all be 0.
+.\"_______________________________________________________
+.SS
+Allowance for Future Attribute Expansion
+.PP
+To allow for the future expansion and addition of fields to any fixed-size
+structure attribute,
+.BR fsinfo ()
+makes the following guarantees:
+.RS 4m
+.IP (1) 4m
+It will always clear any excess space in the buffer.
+.IP (2) 4m
+It will always return the actual size of the data.
+.IP (3) 4m
+It will truncate the data to fit it into the buffer rather than giving an
+error.
+.IP (4) 4m
+Any new version of a structure will incorporate all the fields from the old
+version at same offsets.
+.RE
+.PP
+So, for example, if the caller is running on an older version of the kernel
+with an older, smaller version of the structure than was asked for, the kernel
+will write the smaller version into the buffer and will clear the remainder of
+the buffer to make sure any additional fields are set to 0. The function will
+return the actual size of the data.
+.PP
+On the other hand, if the caller is running on a newer version of the kernel
+with a newer version of the structure that is larger than the buffer, the write
+to the buffer will be truncated to fit as necessary and the actual size of the
+data will be returned.
+.PP
+Note that this doesn't apply to variable-length string attributes.
+
+.\"_______________________________________________________
+.SS
+Invoking \fBfsinfo\fR():
+.PP
+To access a file's status, no permissions are required on the file itself, but
+in the case of
+.BR fsinfo ()
+with a path, execute (search) permission is required on all of the directories
+in
+.I pathname
+that lead to the file.
+.PP
+.BR fsinfo ()
+uses
+.IR pathname ", " dirfd " and " params->at_flags
+to locate the target file in one of a variety of ways:
+.TP
+[*] By absolute path.
+.I pathname
+points to an absolute path and
+.I dirfd
+is ignored. The file is looked up by name, starting from the root of the
+filesystem as seen by the calling process.
+.TP
+[*] By cwd-relative path.
+.I pathname
+points to a relative path and
+.IR dirfd " is " AT_FDCWD .
+The file is looked up by name, starting from the current working directory.
+.TP
+[*] By dir-relative path.
+.I pathname
+points to relative path and
+.I dirfd
+indicates a file descriptor pointing to a directory. The file is looked up by
+name, starting from the directory specified by
+.IR dirfd .
+.TP
+[*] By file descriptor.
+.IR pathname " is " NULL " and " dirfd
+indicates a file descriptor. The file attached to the file descriptor is
+queried directly. The file descriptor may point to any type of file, not just
+a directory.
+.PP
+.I flags
+can be used to influence a path-based lookup. A value for
+.I flags
+is constructed by OR'ing together zero or more of the following constants:
+.TP
+.BR AT_EMPTY_PATH
+.\" commit 65cfc6722361570bfe255698d9cd4dccaf47570d
+If
+.I pathname
+is an empty string, operate on the file referred to by
+.IR dirfd
+(which may have been obtained using the
+.BR open (2)
+.B O_PATH
+flag).
+If
+.I dirfd
+is
+.BR AT_FDCWD ,
+the call operates on the current working directory.
+In this case,
+.I dirfd
+can refer to any type of file, not just a directory.
+This flag is Linux-specific; define
+.B _GNU_SOURCE
+.\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed
+to obtain its definition.
+.TP
+.BR AT_NO_AUTOMOUNT
+Don't automount the terminal ("basename") component of
+.I pathname
+if it is a directory that is an automount point. This allows the caller to
+gather attributes of the filesystem holding an automount point (rather than
+the filesystem it would mount). This flag can be used in tools that scan
+directories to prevent mass-automounting of a directory of automount points.
+The
+.B AT_NO_AUTOMOUNT
+flag has no effect if the mount point has already been mounted over.
+This flag is Linux-specific; define
+.B _GNU_SOURCE
+.\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed
+to obtain its definition.
+.TP
+.B AT_SYMLINK_NOFOLLOW
+If
+.I pathname
+is a symbolic link, do not dereference it:
+instead return information about the link itself, like
+.BR lstat ().
+.SH THE ATTRIBUTES
+.PP
+There is a range of attributes that can be selected from. These are:
+
+.\" __________________ fsinfo_attr_statfs __________________
+.TP
+.B fsinfo_attr_statfs
+This retrieves the "dynamic"
+.B statfs
+information, such as block and file counts, that are expected to change whilst
+a filesystem is being used. This fills in the following structure:
+.PP
+.RS
+.in +4n
+.nf
+struct fsinfo_statfs {
+ __u64 f_blocks; /* Total number of blocks in fs */
+ __u64 f_bfree; /* Total number of free blocks */
+ __u64 f_bavail; /* Number of free blocks available to ordinary user */
+ __u64 f_files; /* Total number of file nodes in fs */
+ __u64 f_ffree; /* Number of free file nodes */
+ __u64 f_favail; /* Number of free file nodes available to ordinary user */
+ __u32 f_bsize; /* Optimal block size */
+ __u32 f_frsize; /* Fragment size */
+};
+.fi
+.in
+.RE
+.IP
+The fields correspond to those of the same name returned by
+.BR statfs ().
+
+.\" __________________ fsinfo_attr_fsinfo __________________
+.TP
+.B fsinfo_attr_fsinfo
+This retrieves information about the
+.BR fsinfo ()
+system call itself. This fills in the following structure:
+.PP
+.RS
+.in +4n
+.nf
+struct fsinfo_fsinfo {
+ __u32 max_attr;
+ __u32 max_cap;
+};
+.fi
+.in
+.RE
+.IP
+The
+.I max_attr
+value indicates the number of attributes supported by the
+.BR fsinfo ()
+system call, and
+.I max_cap
+indicates the number of capability bits supported by the
+.B fsinfo_attr_capabilities
+attribute. The first corresponds to
+.I fsinfo_attr__nr
+and the second to
+.I fsinfo_cap__nr
+in the header file.
+
+.\" __________________ fsinfo_attr_ids __________________
+.TP
+.B fsinfo_attr_ids
+This retrieves a number of fixed IDs and other static information otherwise
+available through
+.BR statfs ().
+The following structure is filled in:
+.PP
+.RS
+.in +4n
+.nf
+struct fsinfo_ids {
+ char f_fs_name[15 + 1]; /* Filesystem name */
+ __u64 f_flags; /* Filesystem mount flags (MS_*) */
+ __u64 f_fsid; /* Short 64-bit Filesystem ID */
+ __u64 f_sb_id; /* Internal superblock ID */
+ __u32 f_fstype; /* Filesystem type from linux/magic.h */
+ __u32 f_dev_major; /* As st_dev_* from struct statx */
+ __u32 f_dev_minor;
+};
+.fi
+.in
+.RE
+.IP
+Most of these are filled in as for
+.BR statfs (),
+with the addition of the filesystem's symbolic name in
+.I f_fs_name
+and an identifier for use in notifications in
+.IR f_sb_id .
+
+.\" __________________ fsinfo_attr_limits __________________
+.TP
+.B fsinfo_attr_limits
+This retrieves information about the limits of what a filesystem can support.
+The following structure is filled in:
+.PP
+.RS
+.in +4n
+.nf
+struct fsinfo_limits {
+ __u64 max_file_size;
+ __u64 max_uid;
+ __u64 max_gid;
+ __u64 max_projid;
+ __u32 max_dev_major;
+ __u32 max_dev_minor;
+ __u32 max_hard_links;
+ __u32 max_xattr_body_len;
+ __u16 max_xattr_name_len;
+ __u16 max_filename_len;
+ __u16 max_symlink_len;
+ __u16 __reserved[1];
+};
+.fi
+.in
+.RE
+.IP
+These indicate the maximum supported sizes for a variety of filesystem objects,
+including the file size, the extended attribute name length and body length,
+the filename length and the symlink body length.
+.IP
+It also indicates the maximum representable values for a User ID, a Group ID,
+a Project ID, a device major number and a device minor number.
+.IP
+And finally, it indicates the maximum number of hard links that can be made to
+a file.
+.IP
+Note that some of these values may be zero if the underlying object or concept
+is not supported by the filesystem or the medium.
+
+.\" __________________ fsinfo_attr_supports __________________
+.TP
+.B fsinfo_attr_supports
+This retrieves information about what bits a filesystem supports in various
+masks. The following structure is filled in:
+.PP
+.RS
+.in +4n
+.nf
+struct fsinfo_supports {
+ __u64 stx_attributes;
+ __u32 stx_mask;
+ __u32 ioc_flags;
+ __u32 win_file_attrs;
+ __u32 __reserved[1];
+};
+.fi
+.in
+.RE
+.IP
+The
+.IR stx_attributes " and " stx_mask
+fields indicate what bits in the struct statx fields of the matching names
+are supported by the filesystem.
+.IP
+The
+.I ioc_flags
+field indicates what FS_*_FL flag bits as used through the FS_IOC_GET/SETFLAGS
+ioctls are supported by the filesystem.
+.IP
+The
+.I win_file_attrs
+indicates what DOS/Windows file attributes a filesystem supports, if any.
+
+.\" __________________ fsinfo_attr_capabilities __________________
+.TP
+.B fsinfo_attr_capabilities
+This retrieves information about what features a filesystem supports as a
+series of single bit indicators. The following structure is filled in:
+.PP
+.RS
+.in +4n
+.nf
+struct fsinfo_capabilities {
+ __u8 capabilities[(fsinfo_cap__nr + 7) / 8];
+};
+.fi
+.in
+.RE
+.IP
+where the bit of interest can be found by:
+.PP
+.RS
+.in +4n
+.nf
+ p->capabilities[bit / 8] & (1 << (bit % 8)))
+.fi
+.in
+.RE
+.IP
+The bits are listed by
+.I enum fsinfo_capability
+and
+.B fsinfo_cap__nr
+is one more than the last capability bit listed in the header file.
+.IP
+Note that the number of capability bits actually supported by the kernel can be
+found using the
+.B fsinfo_attr_fsinfo
+attribute.
+.IP
+The capability bits and their meanings are listed below in the "THE
+CAPABILITIES" section.
+
+.\" __________________ fsinfo_attr_timestamp_info __________________
+.TP
+.B fsinfo_attr_timestamp_info
+This retrieves information about what timestamp resolution and scope is
+supported by a filesystem for each of the file timestamps. The following
+structure is filled in:
+.PP
+.RS
+.in +4n
+.nf
+struct fsinfo_timestamp_info {
+ __s64 minimum_timestamp;
+ __s64 maximum_timestamp;
+ __u16 atime_gran_mantissa;
+ __u16 btime_gran_mantissa;
+ __u16 ctime_gran_mantissa;
+ __u16 mtime_gran_mantissa;
+ __s8 atime_gran_exponent;
+ __s8 btime_gran_exponent;
+ __s8 ctime_gran_exponent;
+ __s8 mtime_gran_exponent;
+ __u32 __reserved[1];
+};
+.fi
+.in
+.RE
+.IP
+where
+.IR minimum_timestamp " and " maximum_timestamp
+are the limits on the timestamps that the filesystem supports and
+.IR *time_gran_mantissa " and " *time_gran_exponent
+indicate the granularity of each timestamp in terms of seconds, using the
+formula:
+.PP
+.RS
+.in +4n
+.nf
+mantissa * pow(10, exponent) Seconds
+.fi
+.in
+.RE
+.IP
+where exponent may be negative and the result may be a fraction of a second.
+.IP
+Four timestamps are detailed: \fBA\fPccess time, \fBB\fPirth/creation time,
+\fBC\fPhange time and \fBM\fPodification time. Capability bits are defined
+that specify whether each of these exist in the filesystem or not.
+.IP
+Note that the timestamp description may be approximated or inaccurate if the
+file is actually remote or is the union of multiple objects.
+
+.\" __________________ fsinfo_attr_volume_id __________________
+.TP
+.B fsinfo_attr_volume_id
+This retrieves the system's superblock volume identifier as a variable-length
+string. This does not necessarily represent a value stored in the medium but
+might be constructed on the fly.
+.IP
+For instance, for a block device this is the block device identifier
+(eg. "sdb2"); for AFS this would be the numeric volume identifier.
+
+.\" __________________ fsinfo_attr_volume_uuid __________________
+.TP
+.B fsinfo_attr_volume_uuid
+This retrieves the volume UUID, if there is one, as a little-endian binary
+UUID. This fills in the following structure:
+.PP
+.RS
+.in +4n
+.nf
+struct fsinfo_volume_uuid {
+ __u8 uuid[16];
+};
+.fi
+.in
+.RE
+.IP
+
+.\" __________________ fsinfo_attr_volume_name __________________
+.TP
+.B fsinfo_attr_volume_name
+This retrieves the filesystem's volume name as a variable-length string. This
+is expected to represent a name stored in the medium.
+.IP
+For a block device, this might be a label stored in the superblock. For a
+network filesystem, this might be a logical volume name of some sort.
+
+.\" __________________ fsinfo_attr_cell/domain __________________
+.PP
+.B fsinfo_attr_cell_name
+.br
+.B fsinfo_attr_domain_name
+.br
+.IP
+These two attributes are variable-length string attributes that may be used to
+obtain information about network filesystems. An AFS volume, for instance,
+belongs to a named cell. CIFS shares may belong to a domain.
+
+.\" __________________ fsinfo_attr_realm_name __________________
+.TP
+.B fsinfo_attr_realm_name
+This attribute is variable-length string that indicates the Kerberos realm that
+a filesystem's authentication tokens should come from.
+
+.\" __________________ fsinfo_attr_server_name __________________
+.TP
+.B fsinfo_attr_server_name
+This attribute is a multiple-value attribute that lists the names of the
+servers that are backing a network filesystem. Each value is a variable-length
+string. The values are enumerated by calling
+.BR fsinfo ()
+multiple times, incrementing
+.I params->Nth
+each time until an ENODATA error occurs, thereby indicating the end of the
+list.
+
+.\" __________________ fsinfo_attr_server_address __________________
+.TP
+.B fsinfo_attr_server_address
+This attribute is a multiple-instance, multiple-value attribute that lists the
+addresses of the servers that are backing a network filesystem. Each value is
+a structure of the following type:
+.PP
+.RS
+.in +4n
+.nf
+struct fsinfo_server_address {
+ struct __kernel_sockaddr_storage address;
+};
+.fi
+.in
+.RE
+.IP
+Where the address may be AF_INET, AF_INET6, AF_RXRPC or any other type as
+appropriate to the filesystem.
+.IP
+The values are enumerated by calling
+.IR fsinfo ()
+multiple times, incrementing
+.I params->Nth
+to step through the servers and
+.I params->Mth
+to step through the addresses of the Nth server each time until ENODATA errors
+occur, thereby indicating either the end of a server's address list or the end
+of the server list.
+.IP
+Barring the server list changing whilst being accessed, it is expected that the
+.I params->Nth
+will correspond to
+.I params->Nth
+for
+.BR fsinfo_attr_server_name .
+
+.\" __________________ fsinfo_attr_parameter __________________
+.TP
+.B fsinfo_attr_parameter
+This attribute is a multiple-value attribute that lists the values of the mount
+parameters for a filesystem as variable-length strings.
+.IP
+The parameters are enumerated by calling
+.BR fsinfo ()
+multiple times, incrementing
+.I params->Nth
+to step through them until error ENODATA is given.
+.IP
+Parameter strings are presented in a form akin to the way they're passed to the
+context created by the
+.BR fsopen ()
+system call. For example, straight text parameters will be rendered as
+something like:
+.PP
+.RS
+.in +4n
+.nf
+"o data=journal"
+"o noquota"
+.fi
+.in
+.RE
+.IP
+Where the initial "word" indicates the option form.
+
+.\" __________________ fsinfo_attr_source __________________
+.TP
+.B fsinfo_attr_source
+This attribute is a multiple-value attribute that lists the mount sources for a
+filesystem as variable-length strings. Normally only one source will be
+available, but the possibility of having more than one is allowed for.
+.IP
+The sources are enumerated by calling
+.BR fsinfo ()
+multiple times, incrementing
+.I params->Nth
+to step through them until error ENODATA is given.
+.IP
+Source strings are presented in a form akin to the way they're passed to the
+context created by the
+.BR fsopen ()
+system call. For example, they will be rendered as something like:
+.PP
+.RS
+.in +4n
+.nf
+"s /dev/sda1"
+"s example.com/pub/linux/"
+.fi
+.in
+.RE
+.IP
+Where the initial "word" indicates the option form.
+
+.\" __________________ fsinfo_attr_name_encoding __________________
+.TP
+.B fsinfo_attr_name_encoding
+This attribute is variable-length string that indicates the filename encoding
+used by the filesystem. The default is "utf8". Note that this may indicate a
+non-8-bit encoding if that's what the underlying filesystem actually supports.
+
+.\" __________________ fsinfo_attr_name_codepage __________________
+.TP
+.B fsinfo_attr_name_codepage
+This attribute is variable-length string that indicates the codepage used to
+translate filenames from the filesystem to the system if this is applicable to
+the filesystem.
+
+.\" __________________ fsinfo_attr_io_size __________________
+.TP
+.B fsinfo_attr_io_size
+This retrieves information about the I/O sizes supported by the filesystem.
+The following structure is filled in:
+.PP
+.RS
+.in +4n
+.nf
+struct fsinfo_io_size {
+ __u32 block_size;
+ __u32 max_single_read_size;
+ __u32 max_single_write_size;
+ __u32 best_read_size;
+ __u32 best_write_size;
+};
+.fi
+.in
+.RE
+.IP
+Where
+.I block_size
+indicates the fundamental I/O block size of the filesystem as something
+O_DIRECT read/write sizes must be a multiple of;
+.IR max_single_write_size " and " max_single_write_size
+indicate the maximum sizes for individual unbuffered data transfer operations;
+and
+.IR best_read_size " and " best_write_size
+indicate the recommended I/O sizes.
+.IP
+Note that any of these may be zero if inapplicable or indeterminable.
+
+
+
+.SH THE CAPABILITIES
+.PP
+There are number of capability bits in a bit array that can be retrieved using
+.BR fsinfo_attr_capabilities .
+These give information about features of the filesystem driver and the specific
+filesystem.
+
+.\" __________________ fsinfo_cap_is_*_fs __________________
+.PP
+.B fsinfo_cap_is_kernel_fs
+.br
+.B fsinfo_cap_is_block_fs
+.br
+.B fsinfo_cap_is_flash_fs
+.br
+.B fsinfo_cap_is_network_fs
+.br
+.B fsinfo_cap_is_automounter_fs
+.IP
+These indicate the primary type of the filesystem.
+.B kernel
+filesystems are special communication interfaces that substitute files for
+system calls; examples include procfs and sysfs.
+.B block
+filesystems require a block device on which to operate; examples include ext4
+and XFS.
+.B flash
+filesystems require an MTD device on which to operate; examples include JFFS2.
+.B network
+filesystems require access to the network and contact one or more servers;
+examples include NFS and AFS.
+.B automounter
+filesystems are kernel special filesystems that host automount points and
+triggers to dynamically create automount points. Examples include autofs and
+AFS's dynamic root.
+
+.\" __________________ fsinfo_cap_automounts __________________
+.TP
+.B fsinfo_cap_automounts
+The filesystem may have automount points that can be triggered by pathwalk.
+
+.\" __________________ fsinfo_cap_adv_locks __________________
+.TP
+.B fsinfo_cap_adv_locks
+The filesystem supports advisory file locks. For a network filesystem, this
+indicates that the advisory file locks are cross-client (and also between
+server and its local filesystem on something like NFS).
+
+.\" __________________ fsinfo_cap_mand_locks __________________
+.TP
+.B fsinfo_cap_mand_locks
+The filesystem supports mandatory file locks. For a network filesystem, this
+indicates that the mandatory file locks are cross-client (and also between
+server and its local filesystem on something like NFS).
+
+.\" __________________ fsinfo_cap_leases __________________
+.TP
+.B fsinfo_cap_leases
+The filesystem supports leases. For a network filesystem, this means that the
+server will tell the client to clean up its state on a file before passing the
+lease to another client.
+
+.\" __________________ fsinfo_cap_*ids __________________
+.PP
+.B fsinfo_cap_uids
+.br
+.B fsinfo_cap_gids
+.br
+.B fsinfo_cap_projids
+.IP
+These indicate that the filesystem supports numeric user IDs, group IDs and
+project IDs respectively.
+
+.\" __________________ fsinfo_cap_id_* __________________
+.PP
+.B fsinfo_cap_id_names
+.br
+.B fsinfo_cap_id_guids
+.IP
+These indicate that the filesystem employs textual names and/or GUIDs as
+identifiers.
+
+.\" __________________ fsinfo_cap_windows_attrs __________________
+.TP
+.B fsinfo_cap_windows_attrs
+Indicates that the filesystem supports some Windows FILE_* attributes.
+
+.\" __________________ fsinfo_cap_*_quotas __________________
+.PP
+.B fsinfo_cap_user_quotas
+.br
+.B fsinfo_cap_group_quotas
+.br
+.B fsinfo_cap_project_quotas
+.IP
+These indicate that the filesystem supports quotas for users, groups and
+projects respectively.
+
+.\" __________________ fsinfo_cap_xattrs/filetypes __________________
+.PP
+.B fsinfo_cap_xattrs
+.br
+.B fsinfo_cap_symlinks
+.br
+.B fsinfo_cap_hard_links
+.br
+.B fsinfo_cap_hard_links_1dir
+.br
+.B fsinfo_cap_device_files
+.br
+.B fsinfo_cap_unix_specials
+.IP
+These indicate that the filesystem supports respectively extended attributes;
+symbolic links; hard links spanning direcories; hard links, but only within a
+directory; block and character device files; and UNIX special files, such as
+FIFO and socket.
+
+.\" __________________ fsinfo_cap_*journal* __________________
+.PP
+.B fsinfo_cap_journal
+.br
+.B fsinfo_cap_data_is_journalled
+.IP
+The first of these indicates that the filesystem has a journal and the second
+that the file data changes are being journalled.
+
+.\" __________________ fsinfo_cap_o_* __________________
+.PP
+.B fsinfo_cap_o_sync
+.br
+.B fsinfo_cap_o_direct
+.IP
+These indicate that O_SYNC and O_DIRECT are supported respectively.
+
+.\" __________________ fsinfo_cap_o_* __________________
+.PP
+.B fsinfo_cap_volume_id
+.br
+.B fsinfo_cap_volume_uuid
+.br
+.B fsinfo_cap_volume_name
+.br
+.B fsinfo_cap_volume_fsid
+.br
+.B fsinfo_cap_cell_name
+.br
+.B fsinfo_cap_domain_name
+.br
+.B fsinfo_cap_realm_name
+.IP
+These indicate if various attributes are supported by the filesystem, where
+.B fsinfo_cap_X
+here corresponds to
+.BR fsinfo_attr_X .
+
+.\" __________________ fsinfo_cap_iver_* __________________
+.PP
+.B fsinfo_cap_iver_all_change
+.br
+.B fsinfo_cap_iver_data_change
+.br
+.B fsinfo_cap_iver_mono_incr
+.IP
+These indicate if
+.I i_version
+on an inode in the filesystem is supported and
+how it behaves.
+.B all_change
+indicates that i_version is incremented on metadata changes as well as data
+changes.
+.B data_change
+indicates that i_version is only incremented on data changes, including
+truncation.
+.B mono_incr
+indicates that i_version is incremented by exactly 1 for each change made.
+
+.\" __________________ fsinfo_cap_resource_forks __________________
+.TP
+.B fsinfo_cap_resource_forks
+This indicates that the filesystem supports some sort of resource fork or
+alternate data stream on a file. This isn't the same as an extended attribute.
+
+.\" __________________ fsinfo_cap_name_* __________________
+.PP
+.B fsinfo_cap_name_case_indep
+.br
+.B fsinfo_cap_name_non_utf8
+.br
+.B fsinfo_cap_name_has_codepage
+.IP
+These indicate certain facts about the filenames in a filesystem: whether
+they're case-independent; if they're not UTF-8; and if there's a codepage
+employed to map the names.
+
+.\" __________________ fsinfo_cap_sparse __________________
+.TP
+.B fsinfo_cap_sparse
+This indicates that the filesystem supports sparse files.
+
+.\" __________________ fsinfo_cap_not_persistent __________________
+.TP
+.B fsinfo_cap_not_persistent
+This indicates that the filesystem is not persistent, and that any data stored
+here will not be saved in the event that the filesystem is unmounted, the
+machine is rebooted or the machine loses power.
+
+.\" __________________ fsinfo_cap_no_unix_mode __________________
+.TP
+.B fsinfo_cap_no_unix_mode
+This indicates that the filesystem doesn't support the UNIX mode permissions
+bits.
+
+.\" __________________ fsinfo_cap_has_*time __________________
+.PP
+.B fsinfo_cap_has_atime
+.br
+.B fsinfo_cap_has_btime
+.br
+.B fsinfo_cap_has_ctime
+.br
+.B fsinfo_cap_has_mtime
+.IP
+These indicate as to what timestamps a filesystem supports, including: Access
+time, Birth/creation time, Change time (metadata and data) and Modification
+time (data only).
+
+
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SH RETURN VALUE
+On success, the size of the value that the kernel has available is returned,
+irrespective of whether the buffer is large enough to hold that. The data
+written to the buffer will be truncated if it is not. On error, \-1 is
+returned, and
+.I errno
+is set appropriately.
+.SH ERRORS
+.TP
+.B EACCES
+Search permission is denied for one of the directories
+in the path prefix of
+.IR pathname .
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.I dirfd
+is not a valid open file descriptor.
+.TP
+.B EFAULT
+.I pathname
+is NULL or
+.IR pathname ", " params " or " buffer
+point to a location outside the process's accessible address space.
+.TP
+.B EINVAL
+Reserved flag specified in
+.IR params->at_flags " or one of " params->__reserved[]
+is not 0.
+.TP
+.B EOPNOTSUPP
+Unsupported attribute requested in
+.IR params->request .
+This may be beyond the limit of the supported attribute set or may just not be
+one that's supported by the filesystem.
+.TP
+.B ENODATA
+Unavailable attribute value requested by
+.IR params->Nth " and/or " params->Mth .
+.TP
+.B ELOOP
+Too many symbolic links encountered while traversing the pathname.
+.TP
+.B ENAMETOOLONG
+.I pathname
+is too long.
+.TP
+.B ENOENT
+A component of
+.I pathname
+does not exist, or
+.I pathname
+is an empty string and
+.B AT_EMPTY_PATH
+was not specified in
+.IR params->at_flags .
+.TP
+.B ENOMEM
+Out of memory (i.e., kernel memory).
+.TP
+.B ENOTDIR
+A component of the path prefix of
+.I pathname
+is not a directory or
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.SH VERSIONS
+.BR fsinfo ()
+was added to Linux in kernel 4.18.
+.SH CONFORMING TO
+.BR fsinfo ()
+is Linux-specific.
+.SH NOTES
+Glibc does not (yet) provide a wrapper for the
+.BR fsinfo ()
+system call; call it using
+.BR syscall (2).
+.SH SEE ALSO
+.BR ioctl_iflags (2),
+.BR statx (2),
+.BR statfs (2)
diff --git a/man2/ioctl_iflags.2 b/man2/ioctl_iflags.2
index 9c77b08b9..49ba4444e 100644
--- a/man2/ioctl_iflags.2
+++ b/man2/ioctl_iflags.2
@@ -200,9 +200,15 @@ the effective user ID of the caller must match the owner of the file,
or the caller must have the
.BR CAP_FOWNER
capability.
+.PP
+The set of flags supported by a filesystem can be determined by calling
+.IR fsinfo (2)
+with attribute
+.IR fsinfo_attr_supports .
.SH SEE ALSO
.BR chattr (1),
.BR lsattr (1),
+.BR fsinfo (2),
.BR mount (2),
.BR btrfs (5),
.BR ext4 (5),
diff --git a/man2/stat.2 b/man2/stat.2
index dad9a01ac..ee4001f85 100644
--- a/man2/stat.2
+++ b/man2/stat.2
@@ -532,6 +532,12 @@ If none of the aforementioned macros are defined,
then the nanosecond values are exposed with names of the form
.IR st_atimensec .
.\"
+.PP
+Which timestamps are supported by a filesystem and their the ranges and
+granularities can be determined by calling
+.IR fsinfo (2)
+with attribute
+.IR fsinfo_attr_timestamp_info .
.SS C library/kernel differences
Over time, increases in the size of the
.I stat
@@ -707,6 +713,7 @@ main(int argc, char *argv[])
.BR access (2),
.BR chmod (2),
.BR chown (2),
+.BR fsinfo (2),
.BR readlink (2),
.BR utime (2),
.BR capabilities (7),
diff --git a/man2/statx.2 b/man2/statx.2
index edac9f6f4..9a57c1b90 100644
--- a/man2/statx.2
+++ b/man2/statx.2
@@ -534,12 +534,25 @@ Glibc does not (yet) provide a wrapper for the
.BR statx ()
system call; call it using
.BR syscall (2).
+.PP
+The sets of mask/stx_mask and stx_attributes bits supported by a filesystem
+can be determined by calling
+.IR fsinfo (2)
+with attribute
+.IR fsinfo_attr_supports .
+.PP
+Which timestamps are supported by a filesystem and their the ranges and
+granularities can also be determined by calling
+.IR fsinfo (2)
+with attribute
+.IR fsinfo_attr_timestamp_info .
.SH SEE ALSO
.BR ls (1),
.BR stat (1),
.BR access (2),
.BR chmod (2),
.BR chown (2),
+.BR fsinfo (2),
.BR readlink (2),
.BR stat (2),
.BR utime (2),
diff --git a/man2/utime.2 b/man2/utime.2
index 03a43a416..c6acdbac2 100644
--- a/man2/utime.2
+++ b/man2/utime.2
@@ -181,9 +181,16 @@ on an append-only file.
.\" is just a wrapper for
.\" .BR utime ()
.\" and hence does not allow a subsecond resolution.
+.PP
+Which timestamps are supported by a filesystem and their the ranges and
+granularities can be determined by calling
+.IR fsinfo (2)
+with attribute
+.IR fsinfo_attr_timestamp_info .
.SH SEE ALSO
.BR chattr (1),
.BR touch (1),
+.BR fsinfo (2),
.BR futimesat (2),
.BR stat (2),
.BR utimensat (2),
diff --git a/man2/utimensat.2 b/man2/utimensat.2
index d61b43e96..be8925548 100644
--- a/man2/utimensat.2
+++ b/man2/utimensat.2
@@ -633,9 +633,16 @@ instead checks whether the
.\" conversely, a process with a read-only file descriptor won't
.\" be able to update the timestamps of a file,
.\" even if it has write permission on the file.
+.PP
+Which timestamps are supported by a filesystem and their the ranges and
+granularities can be determined by calling
+.IR fsinfo (2)
+with attribute
+.IR fsinfo_attr_timestamp_info .
.SH SEE ALSO
.BR chattr (1),
.BR touch (1),
+.BR fsinfo (2),
.BR futimesat (2),
.BR openat (2),
.BR stat (2),
^ permalink raw reply related
* [MANPAGE PATCH] Add manpage for fsopen(2), fspick(2) and fsmount(2)
From: David Howells @ 2018-07-10 22:54 UTC (permalink / raw)
To: Michael Kerrisk
Cc: dhowells, viro, linux-api, linux-fsdevel, torvalds, linux-kernel,
linux-man
In-Reply-To: <153126264966.14533.3388004240803696769.stgit@warthog.procyon.org.uk>
Add a manual page to document the fsopen(), fspick() and fsmount() system
calls.
Signed-off-by: David Howells <dhowells@redhat.com>
---
man2/fsmount.2 | 1
man2/fsopen.2 | 357 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
man2/fspick.2 | 1
3 files changed, 359 insertions(+)
create mode 100644 man2/fsmount.2
create mode 100644 man2/fsopen.2
create mode 100644 man2/fspick.2
diff --git a/man2/fsmount.2 b/man2/fsmount.2
new file mode 100644
index 000000000..2bf59fc3e
--- /dev/null
+++ b/man2/fsmount.2
@@ -0,0 +1 @@
+.so man2/fsopen.2
diff --git a/man2/fsopen.2 b/man2/fsopen.2
new file mode 100644
index 000000000..1bc761ab4
--- /dev/null
+++ b/man2/fsopen.2
@@ -0,0 +1,357 @@
+'\" t
+.\" Copyright (c) 2018 David Howells <dhowells@redhat.com>
+.\"
+.\" %%%LICENSE_START(VERBATIM)
+.\" Permission is granted to make and distribute verbatim copies of this
+.\" manual provided the copyright notice and this permission notice are
+.\" preserved on all copies.
+.\"
+.\" Permission is granted to copy and distribute modified versions of this
+.\" manual under the conditions for verbatim copying, provided that the
+.\" entire resulting derived work is distributed under the terms of a
+.\" permission notice identical to this one.
+.\"
+.\" Since the Linux kernel and libraries are constantly changing, this
+.\" manual page may be incorrect or out-of-date. The author(s) assume no
+.\" responsibility for errors or omissions, or for damages resulting from
+.\" the use of the information contained herein. The author(s) may not
+.\" have taken the same level of care in the production of this manual,
+.\" which is licensed free of charge, as they might when working
+.\" professionally.
+.\"
+.\" Formatted or processed versions of this manual, if unaccompanied by
+.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
+.\"
+.TH FSOPEN 2 2018-06-07 "Linux" "Linux Programmer's Manual"
+.SH NAME
+fsopen, fsmount, fspick \- Handle filesystem (re-)configuration and mounting
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.br
+.B #include <sys/mount.h>
+.br
+.B #include <unistd.h>
+.br
+.BR "#include <fcntl.h> " "/* Definition of AT_* constants */"
+.PP
+.BI "int fsopen(const char *" fsname ", unsigned int " flags );
+.PP
+.BI "int fsmount(int " fd ", unsigned int " flags ", unsigned int " ms_flags );
+.PP
+.BI "int fspick(int " dirfd ", const char *" pathname ", unsigned int " flags );
+.fi
+.PP
+.IR Note :
+There are no glibc wrappers for these system calls.
+.SH DESCRIPTION
+.PP
+.BR fsopen ()
+creates a new filesystem configuration context within the kernel for the
+filesystem named in the
+.I fsname
+parameter and attaches it to a file descriptor, which it then returns. The
+file descriptor can be marked close-on-exec by setting
+.B FSOPEN_CLOEXEC
+in flags.
+.PP
+The
+file descriptor can then be used to configure the desired filesystem parameters
+and security parameters by using
+.BR write (2)
+to pass parameters to it and then writing a command to actually create the
+filesystem representation.
+.PP
+The file descriptor also serves as a channel by which more comprehensive error,
+warning and information messages may be retrieved from the kernel using
+.BR read (2).
+.PP
+Once the kernel's filesystem representation has been created, it can be queried
+by calling
+.BR fsinfo (2)
+on the file descriptor. fsinfo() will spot that the target is actually a
+creation context and look inside that.
+.PP
+.BR fsmount ()
+can then be called to create a mount object that refers to the newly created
+filesystem representation, with the propagation and mount restrictions to be
+applied specified in
+.IR ms_flags .
+The mount object is then attached to a new file descriptor that looks like one
+created by
+.BR open "(2) with " O_PATH " or " open_tree (2).
+This can be passed to
+.BR move_mount (2)
+to attach the mount object to a mountpoint, thereby completing the process.
+.PP
+The file descriptor returned by fsmount() is marked close-on-exec if
+FSMOUNT_CLOEXEC is specified in
+.IR flags .
+.PP
+After fsmount() has completed, the context created by fsopen() is reset and
+moved to reconfiguration state, allowing the new superblock to be reconfigured.
+.PP
+.BR fspick ()
+creates a new filesystem context within the kernel, attaches the superblock
+specified by
+.IR dfd ", " pathname ", " flags
+and puts it into the reconfiguration state and attached the context to a new
+file descriptor that can then be parameterised with
+.BR write (2)
+exactly the same as for the context created by fsopen() above.
+.PP
+.I flags
+is an OR'd together mask of
+.B FSPICK_CLOEXEC
+which indicates that the returned file descriptor should be marked
+close-on-exec and
+.BR FSPICK_SYMLINK_NOFOLLOW ", " FSPICK_NO_AUTOMOUNT " and " FSPICK_EMPTY_PATH
+which control the pathwalk to the target object (see below).
+
+.\"________________________________________________________
+.SS Writable Command Interface
+Superblock (re-)configuration is achieved by writing command strings to the
+context file descriptor using
+.BR write (2).
+Each string is prefixed with a specifier indicating the class of command
+being specified. The available commands include:
+.TP
+\fB"o <option>"\fP
+Specify a filesystem or security parameter.
+.I <option>
+is typically a key or key=val format string. Since the length of the option is
+given to write(), the option may include any sort of character, including
+spaces and commas or even binary data.
+.TP
+\fB"s <name>"\fP
+Specify a device file, network server or other other source specification.
+This may be optional, depending on the filesystem, and it may be possible to
+provide multiple of them to a filesystem.
+.TP
+\fB"x create"\fP
+End the filesystem configuration phase and try and create a representation in
+the kernel with the parameters specified. After this, the context is shifted
+to the mount-pending state waiting for an fsmount() call to occur.
+.TP
+\fB"x reconfigure"\fP
+End a filesystem reconfiguration phase try to apply the parameters to the
+filesystem representation. After this, the context gets reset and put back to
+the start of the reconfiguration phase again.
+.PP
+With this interface, option strings are not limited to 4096 bytes, either
+individually or in sum, and they are also not restricted to text-only options.
+Further, errors may be given individually for each option and not aggregated or
+dumped into the kernel log.
+
+.\"________________________________________________________
+.SS Message Retrieval Interface
+The context file descriptor may be queried for message strings at any time by
+calling
+.BR read (2)
+on the file descriptor. This will return formatted messages that are prefixed
+to indicate their class:
+.TP
+\fB"e <message>"\fP
+An error message string was logged.
+.TP
+\fB"i <message>"\fP
+An informational message string was logged.
+.TP
+\fB"w <message>"\fP
+An warning message string was logged.
+.PP
+Messages are removed from the queue as they're read.
+
+.\"________________________________________________________
+.SH EXAMPLES
+To illustrate the process, here's an example whereby this can be used to mount
+an ext4 filesystem on /dev/sdb1 onto /mnt. Note that the example ignores the
+fact that
+.BR write (2)
+has a length parameter and that errors might occur.
+.PP
+.in +4n
+.nf
+sfd = fsopen("ext4", FSOPEN_CLOEXEC);
+write(sfd, "s /dev/sdb1");
+write(sfd, "o noatime");
+write(sfd, "o acl");
+write(sfd, "o user_attr");
+write(sfd, "o iversion");
+write(sfd, "x create");
+fsinfo(sfd, NULL, ...);
+mfd = fsmount(sfd, FSMOUNT_CLOEXEC, MS_RELATIME);
+move_mount(mfd, "", sfd, AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH);
+.fi
+.in
+.PP
+Here, an ext4 context is created first and attached to sfd. This is then told
+where its source will be, given a bunch of options and created.
+.BR fsinfo (2)
+can then be used to query the filesystem. Then fsmount() is called to create a
+mount object and
+.BR move_mount (2)
+is called to attach it to its intended mountpoint.
+.PP
+And here's an example of mounting from an NFS server:
+.PP
+.in +4n
+.nf
+sfd = fsopen("nfs", 0);
+write(sfd, "s example.com/pub/linux");
+write(sfd, "o nfsvers=3");
+write(sfd, "o rsize=65536");
+write(sfd, "o wsize=65536");
+write(sfd, "o rdma");
+write(sfd, "x create");
+mfd = fsmount(sfd, 0, MS_NODEV);
+move_mount(mfd, "", sfd, AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH);
+.fi
+.in
+.PP
+Reconfiguration can be achieved by:
+.PP
+.in +4n
+.nf
+sfd = fspick(AT_FDCWD, "/mnt", FSPICK_NO_AUTOMOUNT | FSPICK_CLOEXEC);
+write(sfd, "o ro");
+write(sfd, "x reconfigure");
+.fi
+.in
+.PP
+or:
+.PP
+.in +4n
+.nf
+sfd = fsopen(...);
+...
+mfd = fsmount(sfd, ...);
+...
+write(sfd, "o ro");
+write(sfd, "x reconfigure");
+.fi
+.in
+
+
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SH RETURN VALUE
+On success, all three functions return a file descriptor. On error, \-1 is
+returned, and
+.I errno
+is set appropriately.
+.SH ERRORS
+The error values given below result from filesystem type independent
+errors.
+Each filesystem type may have its own special errors and its
+own special behavior.
+See the Linux kernel source code for details.
+.TP
+.B EACCES
+A component of a path was not searchable.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EACCES
+Mounting a read-only filesystem was attempted without giving the
+.B MS_RDONLY
+flag.
+.TP
+.B EACCES
+The block device
+.I source
+is located on a filesystem mounted with the
+.B MS_NODEV
+option.
+.\" mtk: Probably: write permission is required for MS_BIND, with
+.\" the error EPERM if not present; CAP_DAC_OVERRIDE is required.
+.TP
+.B EBUSY
+.I source
+cannot be reconfigured read-only, because it still holds files open for
+writing.
+.TP
+.B EFAULT
+One of the pointer arguments points outside the user address space.
+.TP
+.B EINVAL
+.I source
+had an invalid superblock.
+.TP
+.B EINVAL
+.I ms_flags
+includes more than one of
+.BR MS_SHARED ,
+.BR MS_PRIVATE ,
+.BR MS_SLAVE ,
+or
+.BR MS_UNBINDABLE .
+.TP
+.BR EINVAL
+An attempt was made to bind mount an unbindable mount.
+.TP
+.B ELOOP
+Too many links encountered during pathname resolution.
+.TP
+.B EMFILE
+The system has too many open files to create more.
+.TP
+.B ENFILE
+The process has too many open files to create more.
+.TP
+.B ENAMETOOLONG
+A pathname was longer than
+.BR MAXPATHLEN .
+.TP
+.B ENODEV
+Filesystem
+.I fsname
+not configured in the kernel.
+.TP
+.B ENOENT
+A pathname was empty or had a nonexistent component.
+.TP
+.B ENOMEM
+The kernel could not allocate sufficient memory to complete the call.
+.TP
+.B ENOTBLK
+.I source
+is not a block device (and a device was required).
+.TP
+.B ENOTDIR
+.IR pathname ,
+or a prefix of
+.IR source ,
+is not a directory.
+.TP
+.B ENXIO
+The major number of the block device
+.I source
+is out of range.
+.TP
+.B EPERM
+The caller does not have the required privileges.
+.SH CONFORMING TO
+These functions are Linux-specific and should not be used in programs intended
+to be portable.
+.SH VERSIONS
+.BR fsopen "(), " fsmount "() and " fspick ()
+were added to Linux in kernel 4.18.
+.SH NOTES
+Glibc does not (yet) provide a wrapper for the
+.BR fsopen "() , " fsmount "() or " fspick "()"
+system calls; call them using
+.BR syscall (2).
+.SH SEE ALSO
+.BR mountpoint (1),
+.BR move_mount (2),
+.BR open_tree (2),
+.BR umount (2),
+.BR mount_namespaces (7),
+.BR path_resolution (7),
+.BR findmnt (8),
+.BR lsblk (8),
+.BR mount (8),
+.BR umount (8)
diff --git a/man2/fspick.2 b/man2/fspick.2
new file mode 100644
index 000000000..2bf59fc3e
--- /dev/null
+++ b/man2/fspick.2
@@ -0,0 +1 @@
+.so man2/fsopen.2
^ permalink raw reply related
* Re: [RFC PATCH v2 12/27] x86/mm: Shadow stack page fault error checking
From: Dave Hansen @ 2018-07-10 22:52 UTC (permalink / raw)
To: Yu-cheng Yu, x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar,
linux-kernel, linux-doc, linux-mm, linux-arch, linux-api,
Arnd Bergmann, Andy Lutomirski, Balbir Singh, Cyrill Gorcunov,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek,
Peter Zijlstra <pet>
In-Reply-To: <20180710222639.8241-13-yu-cheng.yu@intel.com>
On 07/10/2018 03:26 PM, Yu-cheng Yu wrote:
> +++ b/arch/x86/include/asm/traps.h
> @@ -157,6 +157,7 @@ enum {
> * bit 3 == 1: use of reserved bit detected
> * bit 4 == 1: fault was an instruction fetch
> * bit 5 == 1: protection keys block access
> + * bit 6 == 1: shadow stack access fault
> */
Could we document this bit better?
Is this a fault where the *processor* thought it should be a shadow
stack fault? Or is it also set on faults to valid shadow stack PTEs
that just happen to fault for other reasons, say protection keys?
^ permalink raw reply
* [MANPAGE PATCH] Add manpages for move_mount(2) and open_tree(2)
From: David Howells @ 2018-07-10 22:52 UTC (permalink / raw)
To: Michael Kerrisk
Cc: dhowells, viro, linux-api, linux-fsdevel, torvalds, linux-kernel,
linux-man
In-Reply-To: <153126249579.14533.18370053915999978123.stgit@warthog.procyon.org.uk>
Add manual pages to document the move_mount and open_tree() system calls.
Signed-off-by: David Howells <dhowells@redhat.com>
---
man2/move_mount.2 | 274 +++++++++++++++++++++++++++++++++++++++++++++++++++++
man2/open_tree.2 | 260 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 534 insertions(+)
create mode 100644 man2/move_mount.2
create mode 100644 man2/open_tree.2
diff --git a/man2/move_mount.2 b/man2/move_mount.2
new file mode 100644
index 000000000..3a819fb84
--- /dev/null
+++ b/man2/move_mount.2
@@ -0,0 +1,274 @@
+'\" t
+.\" Copyright (c) 2018 David Howells <dhowells@redhat.com>
+.\"
+.\" %%%LICENSE_START(VERBATIM)
+.\" Permission is granted to make and distribute verbatim copies of this
+.\" manual provided the copyright notice and this permission notice are
+.\" preserved on all copies.
+.\"
+.\" Permission is granted to copy and distribute modified versions of this
+.\" manual under the conditions for verbatim copying, provided that the
+.\" entire resulting derived work is distributed under the terms of a
+.\" permission notice identical to this one.
+.\"
+.\" Since the Linux kernel and libraries are constantly changing, this
+.\" manual page may be incorrect or out-of-date. The author(s) assume no
+.\" responsibility for errors or omissions, or for damages resulting from
+.\" the use of the information contained herein. The author(s) may not
+.\" have taken the same level of care in the production of this manual,
+.\" which is licensed free of charge, as they might when working
+.\" professionally.
+.\"
+.\" Formatted or processed versions of this manual, if unaccompanied by
+.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
+.\"
+.TH MOVE_MOUNT 2 2018-06-08 "Linux" "Linux Programmer's Manual"
+.SH NAME
+move_mount \- Move mount objects around the filesystem topology
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.br
+.B #include <sys/mount.h>
+.br
+.B #include <unistd.h>
+.br
+.BR "#include <fcntl.h> " "/* Definition of AT_* constants */"
+.PP
+.BI "int move_mount(int " from_dirfd ", const char *" from_pathname ","
+.BI " int " to_dirfd ", const char *" to_pathname ","
+.BI " unsigned int " flags );
+.fi
+.PP
+.IR Note :
+There are no glibc wrappers for these system calls.
+.SH DESCRIPTION
+The
+.BR move_mount ()
+call moves a mount from one place to another; it can also be used to attach an
+unattached mount created by
+.BR fsmount "() or " open_tree "() with " OPEN_TREE_CLONE .
+.PP
+If
+.BR move_mount ()
+is called repeatedly with a file descriptor that refers to a mount object,
+then the object will be attached/moved the first time and then moved again and
+again and again, detaching it from the previous mountpoint each time.
+.PP
+To access the source mount object or the destination mountpoint, no
+permissions are required on the object itself, but if either pathname is
+supplied, execute (search) permission is required on all of the directories
+specified in
+.IR from_pathname " or " to_pathname .
+.PP
+The caller does, however, require the appropriate capabilities or permission
+to effect a mount.
+.PP
+.BR move_mount ()
+uses
+.IR from_pathname ", " from_dirfd " and some " flags
+to locate the mount object to be moved and
+.IR to_pathname ", " to_dirfd " and some other " flags
+to locate the destination mountpoint. Each lookup can be done in one of a
+variety of ways:
+.TP
+[*] By absolute path.
+The pathname points to an absolute path and the dirfd is ignored. The file is
+looked up by name, starting from the root of the filesystem as seen by the
+calling process.
+.TP
+[*] By cwd-relative path.
+The pathname points to a relative path and the dirfd is
+.IR AT_FDCWD .
+The file is looked up by name, starting from the current working directory.
+.TP
+[*] By dir-relative path.
+The pathname points to relative path and the dirfd indicates a file descriptor
+pointing to a directory. The file is looked up by name, starting from the
+directory specified by
+.IR dirfd .
+.TP
+[*] By file descriptor.
+The pathname points to "", the dirfd points directly to the mount object to
+move or the destination mount point and the appropriate
+.B *_EMPTY_PATH
+flag is set.
+.PP
+.I flags
+can be used to influence a path-based lookup. A value for
+.I flags
+is constructed by OR'ing together zero or more of the following constants:
+.TP
+.BR MOVE_MOUNT_F_EMPTY_PATH
+.\" commit 65cfc6722361570bfe255698d9cd4dccaf47570d
+If
+.I from_pathname
+is an empty string, operate on the file referred to by
+.IR from_dirfd
+(which may have been obtained using the
+.BR open (2)
+.B O_PATH
+flag or
+.BR open_tree ())
+If
+.I from_dirfd
+is
+.BR AT_FDCWD ,
+the call operates on the current working directory.
+In this case,
+.I from_dirfd
+can refer to any type of file, not just a directory.
+This flag is Linux-specific; define
+.B _GNU_SOURCE
+.\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed
+to obtain its definition.
+.TP
+.B MOVE_MOUNT_T_EMPTY_PATH
+As above, but operating on
+.IR to_pathname " and " to_dirfd .
+.TP
+.B MOVE_MOUNT_F_NO_AUTOMOUNT
+Don't automount the terminal ("basename") component of
+.I from_pathname
+if it is a directory that is an automount point. This allows a mount object
+that has an automount point at its root to be moved and prevents unintended
+triggering of an automount point.
+The
+.B MOVE_MOUNT_F_NO_AUTOMOUNT
+flag has no effect if the automount point has already been mounted over. This
+flag is Linux-specific; define
+.B _GNU_SOURCE
+.\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed
+to obtain its definition.
+.TP
+.B MOVE_MOUNT_T_NO_AUTOMOUNT
+As above, but operating on
+.IR to_pathname " and " to_dirfd .
+This allows an automount point to be manually mounted over.
+.TP
+.B MOVE_MOUNT_F_SYMLINKS
+If
+.I from_pathname
+is a symbolic link, then dereference it. The default for
+.BR move_mount ()
+is to not follow symlinks.
+.TP
+.B MOVE_MOUNT_T_SYMLINKS
+As above, but operating on
+.IR to_pathname " and " to_dirfd .
+
+.SH EXAMPLES
+The
+.BR move_mount ()
+function can be used like the following:
+.PP
+.RS
+.nf
+move_mount(AT_FDCWD, "/a", AT_FDCWD, "/b", 0);
+.fi
+.RE
+.PP
+This would move the object mounted on "/a" to "/b". It can also be used in
+conjunction with
+.BR open_tree "(2) or " open "(2) with " O_PATH :
+.PP
+.RS
+.nf
+fd = open_tree(AT_FDCWD, "/mnt", 0);
+move_mount(fd, "", AT_FDCWD, "/mnt2", MOVE_MOUNT_F_EMPTY_PATH);
+move_mount(fd, "", AT_FDCWD, "/mnt3", MOVE_MOUNT_F_EMPTY_PATH);
+move_mount(fd, "", AT_FDCWD, "/mnt4", MOVE_MOUNT_F_EMPTY_PATH);
+.fi
+.RE
+.PP
+This would attach the path point for "/mnt" to fd, then it would move the
+mount to "/mnt2", then move it to "/mnt3" and finally to "/mnt4".
+.PP
+It can also be used to attach new mounts:
+.PP
+.RS
+.nf
+sfd = fsopen("ext4", FSOPEN_CLOEXEC);
+write(sfd, "s /dev/sda1");
+write(sfd, "o user_xattr");
+mfd = fsmount(sfd, FSMOUNT_CLOEXEC, MS_NODEV);
+move_mount(mfd, "", AT_FDCWD, "/home", MOVE_MOUNT_F_EMPTY_PATH);
+.fi
+.RE
+.PP
+Which would open the Ext4 filesystem mounted on "/dev/sda1", turn on user
+extended attribute support and create a mount object for it. Finally, the new
+mount object would be attached with
+.BR move_mount ()
+to "/home".
+
+
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SH RETURN VALUE
+On success, 0 is returned. On error, \-1 is returned, and
+.I errno
+is set appropriately.
+.SH ERRORS
+.TP
+.B EACCES
+Search permission is denied for one of the directories
+in the path prefix of
+.IR pathname .
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.IR from_dirfd " or " to_dirfd
+is not a valid open file descriptor.
+.TP
+.B EFAULT
+.IR from_pathname " or " to_pathname
+is NULL or either one point to a location outside the process's accessible
+address space.
+.TP
+.B EINVAL
+Reserved flag specified in
+.IR flags .
+.TP
+.B ELOOP
+Too many symbolic links encountered while traversing the pathname.
+.TP
+.B ENAMETOOLONG
+.IR from_pathname " or " to_pathname
+is too long.
+.TP
+.B ENOENT
+A component of
+.IR from_pathname " or " to_pathname
+does not exist, or one is an empty string and the appropriate
+.B *_EMPTY_PATH
+was not specified in
+.IR flags .
+.TP
+.B ENOMEM
+Out of memory (i.e., kernel memory).
+.TP
+.B ENOTDIR
+A component of the path prefix of
+.IR from_pathname " or " to_pathname
+is not a directory or one or the other is relative and the appropriate
+.I *_dirfd
+is a file descriptor referring to a file other than a directory.
+.SH VERSIONS
+.BR move_mount ()
+was added to Linux in kernel 4.18.
+.SH CONFORMING TO
+.BR move_mount ()
+is Linux-specific.
+.SH NOTES
+Glibc does not (yet) provide a wrapper for the
+.BR move_mount ()
+system call; call it using
+.BR syscall (2).
+.SH SEE ALSO
+.BR fsmount (2),
+.BR fsopen (2),
+.BR open_tree (2)
diff --git a/man2/open_tree.2 b/man2/open_tree.2
new file mode 100644
index 000000000..7e9c86fe3
--- /dev/null
+++ b/man2/open_tree.2
@@ -0,0 +1,260 @@
+'\" t
+.\" Copyright (c) 2018 David Howells <dhowells@redhat.com>
+.\"
+.\" %%%LICENSE_START(VERBATIM)
+.\" Permission is granted to make and distribute verbatim copies of this
+.\" manual provided the copyright notice and this permission notice are
+.\" preserved on all copies.
+.\"
+.\" Permission is granted to copy and distribute modified versions of this
+.\" manual under the conditions for verbatim copying, provided that the
+.\" entire resulting derived work is distributed under the terms of a
+.\" permission notice identical to this one.
+.\"
+.\" Since the Linux kernel and libraries are constantly changing, this
+.\" manual page may be incorrect or out-of-date. The author(s) assume no
+.\" responsibility for errors or omissions, or for damages resulting from
+.\" the use of the information contained herein. The author(s) may not
+.\" have taken the same level of care in the production of this manual,
+.\" which is licensed free of charge, as they might when working
+.\" professionally.
+.\"
+.\" Formatted or processed versions of this manual, if unaccompanied by
+.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
+.\"
+.TH OPEN_TREE 2 2018-06-08 "Linux" "Linux Programmer's Manual"
+.SH NAME
+open_tree \- Pick or clone mount object and attach to fd
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.br
+.B #include <sys/mount.h>
+.br
+.B #include <unistd.h>
+.br
+.BR "#include <fcntl.h> " "/* Definition of AT_* constants */"
+.PP
+.BI "int open_tree(int " dirfd ", const char *" pathname ", unsigned int " flags );
+.fi
+.PP
+.IR Note :
+There are no glibc wrappers for these system calls.
+.SH DESCRIPTION
+.BR open_tree ()
+picks the mount object specified by the pathname and attaches it to a new file
+descriptor or clones it and attaches the clone to the file descriptor. The
+resultant file descriptor is indistinguishable from one produced by
+.BR open "(2) with " O_PATH .
+.PP
+In the case that the mount object is cloned, the clone will be "unmounted" and
+destroyed when the file descriptor is closed if it is not otherwise mounted
+somewhere by calling
+.BR move_mount (2).
+.PP
+To select a mount object, no permissions are required on the object referred
+to by the path, but execute (search) permission is required on all of the
+directories in
+.I pathname
+that lead to the object.
+.PP
+To clone an object, however, the caller must have mount capabilities and
+permissions.
+.PP
+.BR open_tree ()
+uses
+.IR pathname ", " dirfd " and " flags
+to locate the target object in one of a variety of ways:
+.TP
+[*] By absolute path.
+.I pathname
+points to an absolute path and
+.I dirfd
+is ignored. The object is looked up by name, starting from the root of the
+filesystem as seen by the calling process.
+.TP
+[*] By cwd-relative path.
+.I pathname
+points to a relative path and
+.IR dirfd " is " AT_FDCWD .
+The object is looked up by name, starting from the current working directory.
+.TP
+[*] By dir-relative path.
+.I pathname
+points to relative path and
+.I dirfd
+indicates a file descriptor pointing to a directory. The object is looked up
+by name, starting from the directory specified by
+.IR dirfd .
+.TP
+[*] By file descriptor.
+.I pathname
+is "",
+.I dirfd
+indicates a file descriptor and
+.B AT_EMPTY_PATH
+is set in
+.IR flags .
+The mount attached to the file descriptor is queried directly. The file
+descriptor may point to any type of file, not just a directory.
+
+.\"______________________________________________________________
+.PP
+.I flags
+can be used to control the operation of the function and to influence a
+path-based lookup. A value for
+.I flags
+is constructed by OR'ing together zero or more of the following constants:
+.TP
+.BR AT_EMPTY_PATH
+.\" commit 65cfc6722361570bfe255698d9cd4dccaf47570d
+If
+.I pathname
+is an empty string, operate on the file referred to by
+.IR dirfd
+(which may have been obtained from
+.BR open "(2) with"
+.BR O_PATH ", from " fsmount (2)
+or from another
+.BR open_tree ()).
+If
+.I dirfd
+is
+.BR AT_FDCWD ,
+the call operates on the current working directory.
+In this case,
+.I dirfd
+can refer to any type of file, not just a directory.
+This flag is Linux-specific; define
+.B _GNU_SOURCE
+.\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed
+to obtain its definition.
+.TP
+.BR AT_NO_AUTOMOUNT
+Don't automount the terminal ("basename") component of
+.I pathname
+if it is a directory that is an automount point. This flag allows the
+automount point itself to be picked up or a mount cloned that is rooted on the
+automount point. The
+.B AT_NO_AUTOMOUNT
+flag has no effect if the mount point has already been mounted over.
+This flag is Linux-specific; define
+.B _GNU_SOURCE
+.\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed
+to obtain its definition.
+.TP
+.B AT_SYMLINK_NOFOLLOW
+If
+.I pathname
+is a symbolic link, do not dereference it: instead pick up or clone a mount
+rooted on the link itself.
+.TP
+.B OPEN_TREE_CLOEXEC
+Set the close-on-exec flag for the new file descriptor. This will cause the
+file descriptor to be closed automatically when a process exec's.
+.TP
+.B OPEN_TREE_CLONE
+Rather than directly attaching the selected object to the file descriptor,
+clone the object, set the root of the new mount object to that point and
+attach the clone to the file descriptor.
+.TP
+.B AT_RECURSIVE
+This is only permitted in conjunction with OPEN_TREE_CLONE. It causes the
+entire mount subtree rooted at the selected spot to be cloned rather than just
+that one mount object.
+
+
+.SH EXAMPLE
+The
+.BR open_tree ()
+function can be used like the following:
+.PP
+.RS
+.nf
+fd1 = open_tree(AT_FDCWD, "/mnt", 0);
+fd2 = open_tree(fd1, "",
+ AT_EMPTY_PATH | OPEN_TREE_CLONE | AT_RECURSIVE);
+move_mount(fd2, "", AT_FDCWD, "/mnt2", MOVE_MOUNT_F_EMPTY_PATH);
+.fi
+.RE
+.PP
+This would attach the path point for "/mnt" to fd1, then it would copy the
+entire subtree at the point referred to by fd1 and attach that to fd2; lastly,
+it would attach the clone to "/mnt2".
+
+
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SH RETURN VALUE
+On success, the new file descriptor is returned. On error, \-1 is returned,
+and
+.I errno
+is set appropriately.
+.SH ERRORS
+.TP
+.B EACCES
+Search permission is denied for one of the directories
+in the path prefix of
+.IR pathname .
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.I dirfd
+is not a valid open file descriptor.
+.TP
+.B EFAULT
+.I pathname
+is NULL or
+.IR pathname
+point to a location outside the process's accessible address space.
+.TP
+.B EINVAL
+Reserved flag specified in
+.IR flags .
+.TP
+.B ELOOP
+Too many symbolic links encountered while traversing the pathname.
+.TP
+.B ENAMETOOLONG
+.I pathname
+is too long.
+.TP
+.B ENOENT
+A component of
+.I pathname
+does not exist, or
+.I pathname
+is an empty string and
+.B AT_EMPTY_PATH
+was not specified in
+.IR flags .
+.TP
+.B ENOMEM
+Out of memory (i.e., kernel memory).
+.TP
+.B ENOTDIR
+A component of the path prefix of
+.I pathname
+is not a directory or
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.SH VERSIONS
+.BR open_tree ()
+was added to Linux in kernel 4.18.
+.SH CONFORMING TO
+.BR open_tree ()
+is Linux-specific.
+.SH NOTES
+Glibc does not (yet) provide a wrapper for the
+.BR open_tree ()
+system call; call it using
+.BR syscall (2).
+.SH SEE ALSO
+.BR fsmount (2),
+.BR move_mount (2),
+.BR open (2)
^ permalink raw reply related
* [PATCH 31/32] vfs: syscall: Add fsinfo() to query filesystem information [ver #9]
From: David Howells @ 2018-07-10 22:44 UTC (permalink / raw)
To: viro; +Cc: dhowells, linux-api, linux-fsdevel, torvalds, linux-kernel
In-Reply-To: <153126248868.14533.9751473662727327569.stgit@warthog.procyon.org.uk>
Add a system call to allow filesystem information to be queried. A request
value can be given to indicate the desired attribute. Support is provided
for enumerating multi-value attributes.
===============
NEW SYSTEM CALL
===============
The new system call looks like:
int ret = fsinfo(int dfd,
const char *filename,
const struct fsinfo_params *params,
void *buffer,
size_t buf_size);
The params parameter optionally points to a block of parameters:
struct fsinfo_params {
__u32 at_flags;
__u32 request;
__u32 Nth;
__u32 Mth;
__u32 __reserved[6];
};
If params is NULL, it is assumed params->request should be
fsinfo_attr_statfs, params->Nth should be 0, params->Mth should be 0 and
params->at_flags should be 0.
If params is given, all of params->__reserved[] must be 0.
dfd, filename and params->at_flags indicate the file to query. There is no
equivalent of lstat() as that can be emulated with fsinfo() by setting
AT_SYMLINK_NOFOLLOW in params->at_flags. There is also no equivalent of
fstat() as that can be emulated by passing a NULL filename to fsinfo() with
the fd of interest in dfd. AT_NO_AUTOMOUNT can also be used to an allow
automount point to be queried without triggering it.
params->request indicates the attribute/attributes to be queried. This can
be one of:
fsinfo_attr_statfs - statfs-style info
fsinfo_attr_fsinfo - Information about fsinfo()
fsinfo_attr_ids - Filesystem IDs
fsinfo_attr_limits - Filesystem limits
fsinfo_attr_supports - What's supported in statx(), IOC flags
fsinfo_attr_capabilities - Filesystem capabilities
fsinfo_attr_timestamp_info - Inode timestamp info
fsinfo_attr_volume_id - Volume ID (string)
fsinfo_attr_volume_uuid - Volume UUID
fsinfo_attr_volume_name - Volume name (string)
fsinfo_attr_cell_name - Cell name (string)
fsinfo_attr_domain_name - Domain name (string)
fsinfo_attr_realm_name - Realm name (string)
fsinfo_attr_server_name - Name of the Nth server (string)
fsinfo_attr_server_address - Mth address of the Nth server
fsinfo_attr_parameter - Nth mount parameter (string)
fsinfo_attr_source - Nth mount source name (string)
fsinfo_attr_name_encoding - Filename encoding (string)
fsinfo_attr_name_codepage - Filename codepage (string)
fsinfo_attr_io_size - Optimal I/O sizes
Some attributes (such as the servers backing a network filesystem) can have
multiple values. These can be enumerated by setting params->Nth and
params->Mth to 0, 1, ... until ENODATA is returned.
buffer and buf_size point to the reply buffer. The buffer is filled up to
the specified size, even if this means truncating the reply. The full size
of the reply is returned. In future versions, this will allow extra fields
to be tacked on to the end of the reply, but anyone not expecting them will
only get the subset they're expecting. If either buffer of buf_size are 0,
no copy will take place and the data size will be returned.
At the moment, this will only work on x86_64 and i386 as it requires the
system call to be wired up.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-api@vger.kernel.org
---
arch/x86/entry/syscalls/syscall_32.tbl | 1
arch/x86/entry/syscalls/syscall_64.tbl | 1
fs/statfs.c | 470 ++++++++++++++++++++++++++++
include/linux/fs.h | 4
include/linux/fsinfo.h | 40 ++
include/linux/syscalls.h | 4
include/uapi/linux/fsinfo.h | 237 ++++++++++++++
samples/statx/Makefile | 5
samples/statx/test-fsinfo.c | 539 ++++++++++++++++++++++++++++++++
9 files changed, 1300 insertions(+), 1 deletion(-)
create mode 100644 include/linux/fsinfo.h
create mode 100644 include/uapi/linux/fsinfo.h
create mode 100644 samples/statx/test-fsinfo.c
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 5587bcede253..1c9b56f80cdf 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -403,3 +403,4 @@
389 i386 fsopen sys_fsopen __ia32_sys_fsopen
390 i386 fsmount sys_fsmount __ia32_sys_fsmount
391 i386 fspick sys_fspick __ia32_sys_fspick
+392 i386 fsinfo sys_fsinfo __ia32_sys_fsinfo
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 460a464024bf..d2a4d6db4df6 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -348,6 +348,7 @@
337 common fsopen __x64_sys_fsopen
338 common fsmount __x64_sys_fsmount
339 common fspick __x64_sys_fspick
+340 common fsinfo __x64_sys_fsinfo
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/statfs.c b/fs/statfs.c
index 5b2a24f0f263..fa6be965dce1 100644
--- a/fs/statfs.c
+++ b/fs/statfs.c
@@ -9,6 +9,7 @@
#include <linux/security.h>
#include <linux/uaccess.h>
#include <linux/compat.h>
+#include <linux/fsinfo.h>
#include "internal.h"
static int flags_by_mnt(int mnt_flags)
@@ -384,3 +385,472 @@ COMPAT_SYSCALL_DEFINE2(ustat, unsigned, dev, struct compat_ustat __user *, u)
return 0;
}
#endif
+
+/*
+ * Get basic filesystem stats from statfs.
+ */
+static int fsinfo_generic_statfs(struct dentry *dentry,
+ struct fsinfo_statfs *p)
+{
+ struct super_block *sb;
+ struct kstatfs buf;
+ int ret;
+
+ ret = statfs_by_dentry(dentry, &buf);
+ if (ret < 0)
+ return ret;
+
+ sb = dentry->d_sb;
+ p->f_blocks = buf.f_blocks;
+ p->f_bfree = buf.f_bfree;
+ p->f_bavail = buf.f_bavail;
+ p->f_files = buf.f_files;
+ p->f_ffree = buf.f_ffree;
+ p->f_favail = buf.f_ffree;
+ p->f_bsize = buf.f_bsize;
+ p->f_frsize = buf.f_frsize;
+ return sizeof(*p);
+}
+
+static int fsinfo_generic_ids(struct dentry *dentry,
+ struct fsinfo_ids *p)
+{
+ struct super_block *sb;
+ struct kstatfs buf;
+ int ret;
+
+ ret = statfs_by_dentry(dentry, &buf);
+ if (ret < 0)
+ return ret;
+
+ sb = dentry->d_sb;
+ p->f_fstype = sb->s_magic;
+ p->f_dev_major = MAJOR(sb->s_dev);
+ p->f_dev_minor = MINOR(sb->s_dev);
+ p->f_flags = ST_VALID | flags_by_sb(sb->s_flags);
+
+ memcpy(&p->f_fsid, &buf.f_fsid, sizeof(p->f_fsid));
+ strcpy(p->f_fs_name, dentry->d_sb->s_type->name);
+ return sizeof(*p);
+}
+
+static int fsinfo_generic_limits(struct dentry *dentry,
+ struct fsinfo_limits *lim)
+{
+ struct super_block *sb = dentry->d_sb;
+
+ lim->max_file_size = sb->s_maxbytes;
+ lim->max_hard_links = sb->s_max_links;
+ lim->max_uid = UINT_MAX;
+ lim->max_gid = UINT_MAX;
+ lim->max_projid = UINT_MAX;
+ lim->max_filename_len = NAME_MAX;
+ lim->max_symlink_len = PAGE_SIZE;
+ lim->max_xattr_name_len = XATTR_NAME_MAX;
+ lim->max_xattr_body_len = XATTR_SIZE_MAX;
+ lim->max_dev_major = 0xffffff;
+ lim->max_dev_minor = 0xff;
+ return sizeof(*lim);
+}
+
+static int fsinfo_generic_supports(struct dentry *dentry,
+ struct fsinfo_supports *c)
+{
+ struct super_block *sb = dentry->d_sb;
+
+ c->stx_mask = STATX_BASIC_STATS;
+ if (sb->s_d_op && sb->s_d_op->d_automount)
+ c->stx_attributes |= STATX_ATTR_AUTOMOUNT;
+ return sizeof(*c);
+}
+
+static int fsinfo_generic_capabilities(struct dentry *dentry,
+ struct fsinfo_capabilities *c)
+{
+ struct super_block *sb = dentry->d_sb;
+
+ if (sb->s_mtd)
+ fsinfo_set_cap(c, fsinfo_cap_is_flash_fs);
+ else if (sb->s_bdev)
+ fsinfo_set_cap(c, fsinfo_cap_is_block_fs);
+
+ if (sb->s_quota_types & QTYPE_MASK_USR)
+ fsinfo_set_cap(c, fsinfo_cap_user_quotas);
+ if (sb->s_quota_types & QTYPE_MASK_GRP)
+ fsinfo_set_cap(c, fsinfo_cap_group_quotas);
+ if (sb->s_quota_types & QTYPE_MASK_PRJ)
+ fsinfo_set_cap(c, fsinfo_cap_project_quotas);
+ if (sb->s_d_op && sb->s_d_op->d_automount)
+ fsinfo_set_cap(c, fsinfo_cap_automounts);
+ if (sb->s_id[0])
+ fsinfo_set_cap(c, fsinfo_cap_volume_id);
+
+ fsinfo_set_cap(c, fsinfo_cap_has_atime);
+ fsinfo_set_cap(c, fsinfo_cap_has_ctime);
+ fsinfo_set_cap(c, fsinfo_cap_has_mtime);
+ return sizeof(*c);
+}
+
+static int fsinfo_generic_timestamp_info(struct dentry *dentry,
+ struct fsinfo_timestamp_info *ts)
+{
+ struct super_block *sb = dentry->d_sb;
+
+ /* If unset, assume 1s granularity */
+ u16 mantissa = 1;
+ s8 exponent = 0;
+
+ ts->minimum_timestamp = S64_MIN;
+ ts->maximum_timestamp = S64_MAX;
+ if (sb->s_time_gran < 1000000000) {
+ if (sb->s_time_gran < 1000)
+ exponent = -9;
+ else if (sb->s_time_gran < 1000000)
+ exponent = -6;
+ else
+ exponent = -3;
+ }
+#define set_gran(x) \
+ do { \
+ ts->x##_mantissa = mantissa; \
+ ts->x##_exponent = exponent; \
+ } while (0)
+ set_gran(atime_gran);
+ set_gran(btime_gran);
+ set_gran(ctime_gran);
+ set_gran(mtime_gran);
+ return sizeof(*ts);
+}
+
+static int fsinfo_generic_volume_uuid(struct dentry *dentry,
+ struct fsinfo_volume_uuid *vu)
+{
+ struct super_block *sb = dentry->d_sb;
+
+ memcpy(vu, &sb->s_uuid, sizeof(*vu));
+ return sizeof(*vu);
+}
+
+static int fsinfo_generic_volume_id(struct dentry *dentry, char *buf)
+{
+ struct super_block *sb = dentry->d_sb;
+ size_t len = strlen(sb->s_id);
+
+ if (buf)
+ memcpy(buf, sb->s_id, len + 1);
+ return len;
+}
+
+static int fsinfo_generic_name_encoding(struct dentry *dentry, char *buf)
+{
+ static const char encoding[] = "utf8";
+
+ if (buf)
+ memcpy(buf, encoding, sizeof(encoding) - 1);
+ return sizeof(encoding) - 1;
+}
+
+static int fsinfo_generic_io_size(struct dentry *dentry,
+ struct fsinfo_io_size *c)
+{
+ struct super_block *sb = dentry->d_sb;
+ struct kstatfs buf;
+ int ret;
+
+ if (sb->s_op->statfs == simple_statfs) {
+ c->block_size = PAGE_SIZE;
+ c->max_single_read_size = 0;
+ c->max_single_write_size = 0;
+ c->best_read_size = PAGE_SIZE;
+ c->best_write_size = PAGE_SIZE;
+ } else {
+ ret = statfs_by_dentry(dentry, &buf);
+ if (ret < 0)
+ return ret;
+ c->block_size = buf.f_bsize;
+ c->max_single_read_size = buf.f_bsize;
+ c->max_single_write_size = buf.f_bsize;
+ c->best_read_size = PAGE_SIZE;
+ c->best_write_size = PAGE_SIZE;
+ }
+ return sizeof(*c);
+}
+
+/*
+ * Implement some queries generically from stuff in the superblock.
+ */
+int generic_fsinfo(struct dentry *dentry, struct fsinfo_kparams *params)
+{
+#define _gen(X) fsinfo_attr_##X: return fsinfo_generic_##X(dentry, params->buffer)
+
+ switch (params->request) {
+ case _gen(statfs);
+ case _gen(ids);
+ case _gen(limits);
+ case _gen(supports);
+ case _gen(capabilities);
+ case _gen(timestamp_info);
+ case _gen(volume_uuid);
+ case _gen(volume_id);
+ case _gen(name_encoding);
+ case _gen(io_size);
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+EXPORT_SYMBOL(generic_fsinfo);
+
+/*
+ * Retrieve the filesystem info. We make some stuff up if the operation is not
+ * supported.
+ */
+int vfs_fsinfo(const struct path *path, struct fsinfo_kparams *params)
+{
+ struct dentry *dentry = path->dentry;
+ int (*get_fsinfo)(struct dentry *, struct fsinfo_kparams *);
+ int ret;
+
+ if (params->request == fsinfo_attr_fsinfo) {
+ struct fsinfo_fsinfo *info = params->buffer;
+
+ info->max_attr = fsinfo_attr__nr;
+ info->max_cap = fsinfo_cap__nr;
+ return sizeof(*info);
+ }
+
+ get_fsinfo = dentry->d_sb->s_op->get_fsinfo;
+ if (!get_fsinfo) {
+ if (!dentry->d_sb->s_op->statfs)
+ return -EOPNOTSUPP;
+ get_fsinfo = generic_fsinfo;
+ }
+
+ ret = security_sb_statfs(dentry);
+ if (ret)
+ return ret;
+
+ ret = get_fsinfo(dentry, params);
+ if (ret < 0)
+ return ret;
+
+ if (params->request == fsinfo_attr_ids &&
+ params->buffer) {
+ struct fsinfo_ids *p = params->buffer;
+
+ p->f_flags |= flags_by_mnt(path->mnt->mnt_flags);
+ }
+ return ret;
+}
+
+static int vfs_fsinfo_path(int dfd, const char __user *filename,
+ struct fsinfo_kparams *params)
+{
+ struct path path;
+ unsigned lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
+ int ret = -EINVAL;
+
+ if ((params->at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
+ AT_EMPTY_PATH)) != 0)
+ return -EINVAL;
+
+ if (params->at_flags & AT_SYMLINK_NOFOLLOW)
+ lookup_flags &= ~LOOKUP_FOLLOW;
+ if (params->at_flags & AT_NO_AUTOMOUNT)
+ lookup_flags &= ~LOOKUP_AUTOMOUNT;
+ if (params->at_flags & AT_EMPTY_PATH)
+ lookup_flags |= LOOKUP_EMPTY;
+
+retry:
+ ret = user_path_at(dfd, filename, lookup_flags, &path);
+ if (ret)
+ goto out;
+
+ ret = vfs_fsinfo(&path, params);
+ path_put(&path);
+ if (retry_estale(ret, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+out:
+ return ret;
+}
+
+static int vfs_fsinfo_fd(unsigned int fd, struct fsinfo_kparams *params)
+{
+ struct fd f = fdget_raw(fd);
+ int ret = -EBADF;
+
+ if (f.file) {
+ ret = vfs_fsinfo(&f.file->f_path, params);
+ fdput(f);
+ }
+ return ret;
+}
+
+/*
+ * Return buffer information by requestable attribute.
+ *
+ * STRUCT indicates a fixed-size structure with only one instance.
+ * STRUCT_N indicates a fixed-size structure that may have multiple instances.
+ * STRING indicates a string with only one instance.
+ * STRING_N indicates a string that may have multiple instances.
+ * STRUCT_ARRAY indicates an array of fixed-size structs with only one instance.
+ * STRUCT_ARRAY_N as above that may have multiple instances.
+ *
+ * If an entry is marked STRUCT, STRUCT_N or STRUCT_NM then if no buffer is
+ * supplied to sys_fsinfo(), sys_fsinfo() will handle returning the buffer size
+ * without calling vfs_fsinfo() and the filesystem.
+ *
+ * No struct may have more than 252 bytes (ie. 0x3f * 4)
+ */
+#define FSINFO_STRING(N) [fsinfo_attr_##N] = 0x0000
+#define FSINFO_STRUCT(N) [fsinfo_attr_##N] = sizeof(struct fsinfo_##N)
+#define FSINFO_STRING_N(N) [fsinfo_attr_##N] = 0x4000
+#define FSINFO_STRUCT_N(N) [fsinfo_attr_##N] = 0x4000 | sizeof(struct fsinfo_##N)
+#define FSINFO_STRUCT_NM(N) [fsinfo_attr_##N] = 0x8000 | sizeof(struct fsinfo_##N)
+static const u16 fsinfo_buffer_sizes[fsinfo_attr__nr] = {
+ FSINFO_STRUCT (statfs),
+ FSINFO_STRUCT (fsinfo),
+ FSINFO_STRUCT (ids),
+ FSINFO_STRUCT (limits),
+ FSINFO_STRUCT (capabilities),
+ FSINFO_STRUCT (supports),
+ FSINFO_STRUCT (timestamp_info),
+ FSINFO_STRING (volume_id),
+ FSINFO_STRUCT (volume_uuid),
+ FSINFO_STRING (volume_name),
+ FSINFO_STRING (cell_name),
+ FSINFO_STRING (domain_name),
+ FSINFO_STRING (realm_name),
+ FSINFO_STRING_N (server_name),
+ FSINFO_STRUCT_NM (server_address),
+ FSINFO_STRING_N (parameter),
+ FSINFO_STRING_N (source),
+ FSINFO_STRING (name_encoding),
+ FSINFO_STRING (name_codepage),
+ FSINFO_STRUCT (io_size),
+};
+
+/**
+ * sys_fsinfo - System call to get filesystem information
+ * @dfd: Base directory to pathwalk from or fd referring to filesystem.
+ * @filename: Filesystem to query or NULL.
+ * @_params: Parameters to define request (or NULL for enhanced statfs).
+ * @_buffer: Result buffer.
+ * @buf_size: Size of result buffer.
+ *
+ * Get information on a filesystem. The filesystem attribute to be queried is
+ * indicated by @_params->request, and some of the attributes can have multiple
+ * values, indexed by @_params->Nth and @_params->Mth. If @_params is NULL,
+ * then the 0th fsinfo_attr_statfs attribute is queried. If an attribute does
+ * not exist, EOPNOTSUPP is returned; if the Nth,Mth value does not exist,
+ * ENODATA is returned.
+ *
+ * On success, the size of the attribute's value is returned. If @buf_size is
+ * 0 or @_buffer is NULL, only the size is returned. If the size of the value
+ * is larger than @buf_size, it will be truncated by the copy. If the size of
+ * the value is smaller than @buf_size then the excess buffer space will be
+ * cleared. The full size of the value will be returned, irrespective of how
+ * much data is actually placed in the buffer.
+ */
+SYSCALL_DEFINE5(fsinfo,
+ int, dfd, const char __user *, filename,
+ struct fsinfo_params __user *, _params,
+ void __user *, _buffer, size_t, buf_size)
+{
+ struct fsinfo_params user_params;
+ struct fsinfo_kparams params;
+ size_t size;
+ int ret;
+
+ if (_params) {
+ if (copy_from_user(&user_params, _params, sizeof(user_params)))
+ return -EFAULT;
+ if (user_params.__reserved[0] ||
+ user_params.__reserved[1] ||
+ user_params.__reserved[2] ||
+ user_params.__reserved[3] ||
+ user_params.__reserved[4] ||
+ user_params.__reserved[5])
+ return -EINVAL;
+ if (user_params.request >= fsinfo_attr__nr)
+ return -EOPNOTSUPP;
+ params.at_flags = user_params.at_flags;
+ params.request = user_params.request;
+ params.Nth = user_params.Nth;
+ params.Mth = user_params.Mth;
+ } else {
+ params.at_flags = 0;
+ params.request = fsinfo_attr_statfs;
+ params.Nth = 0;
+ params.Mth = 0;
+ }
+
+ if (!_buffer || !buf_size) {
+ buf_size = 0;
+ _buffer = NULL;
+ }
+
+ /* Allocate an appropriately-sized buffer. We will truncate the
+ * contents when we write the contents back to userspace.
+ */
+ size = fsinfo_buffer_sizes[params.request];
+ switch (size & 0xc000) {
+ case 0x0000:
+ if (params.Nth != 0)
+ return -ENODATA;
+ /* Fall through */
+ case 0x4000:
+ if (params.Mth != 0)
+ return -ENODATA;
+ /* Fall through */
+ case 0x8000:
+ break;
+ case 0xc000:
+ return -ENOBUFS;
+ }
+
+ size &= ~0xc000;
+ if (size == 0) {
+ size = 4096; /* String */
+ } else {
+ if (buf_size == 0)
+ return size; /* We know how big the buffer should be */
+
+ /* Clear any part of the buffer that we won't fill. */
+ if (buf_size > size &&
+ clear_user(_buffer, buf_size) != 0)
+ return -EFAULT;
+ }
+
+ if (buf_size > 0) {
+ params.buf_size = size;
+ params.buffer = kzalloc(size, GFP_KERNEL);
+ if (!params.buffer)
+ return -ENOMEM;
+ } else {
+ params.buf_size = 0;
+ params.buffer = NULL;
+ }
+
+ if (filename)
+ ret = vfs_fsinfo_path(dfd, filename, ¶ms);
+ else
+ ret = vfs_fsinfo_fd(dfd, ¶ms);
+ if (ret < 0)
+ goto error;
+
+ if (ret == 0) {
+ ret = -ENODATA;
+ goto error;
+ }
+
+ if (buf_size > ret)
+ buf_size = ret;
+
+ if (copy_to_user(_buffer, params.buffer, buf_size))
+ ret = -EFAULT;
+error:
+ kfree(params.buffer);
+ return ret;
+}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e6d963f2fdc2..bcbe94c0dfe8 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -62,6 +62,8 @@ struct iov_iter;
struct fscrypt_info;
struct fscrypt_operations;
struct fs_context;
+struct fsinfo_kparams;
+enum fsinfo_attribute;
extern void __init inode_init(void);
extern void __init inode_init_early(void);
@@ -1847,6 +1849,7 @@ struct super_operations {
int (*thaw_super) (struct super_block *);
int (*unfreeze_fs) (struct super_block *);
int (*statfs) (struct dentry *, struct kstatfs *);
+ int (*get_fsinfo) (struct dentry *, struct fsinfo_kparams *);
int (*remount_fs) (struct super_block *, int *, char *, size_t);
int (*reconfigure) (struct super_block *, struct fs_context *);
void (*umount_begin) (struct super_block *);
@@ -2223,6 +2226,7 @@ extern int iterate_mounts(int (*)(struct vfsmount *, void *), void *,
extern int vfs_statfs(const struct path *, struct kstatfs *);
extern int user_statfs(const char __user *, struct kstatfs *);
extern int fd_statfs(int, struct kstatfs *);
+extern int vfs_fsinfo(const struct path *, struct fsinfo_kparams *);
extern int freeze_super(struct super_block *super);
extern int thaw_super(struct super_block *super);
extern bool our_mnt(struct vfsmount *mnt);
diff --git a/include/linux/fsinfo.h b/include/linux/fsinfo.h
new file mode 100644
index 000000000000..c356391b4b2a
--- /dev/null
+++ b/include/linux/fsinfo.h
@@ -0,0 +1,40 @@
+/* Filesystem information query
+ *
+ * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#ifndef _LINUX_FSINFO_H
+#define _LINUX_FSINFO_H
+
+#include <uapi/linux/fsinfo.h>
+
+struct fsinfo_kparams {
+ __u32 at_flags; /* AT_SYMLINK_NOFOLLOW and similar */
+ enum fsinfo_attribute request; /* What is being asking for */
+ __u32 Nth; /* Instance of it (some may have multiple) */
+ __u32 Mth; /* Subinstance */
+ void *buffer; /* Where to place the reply */
+ size_t buf_size; /* Size of the buffer */
+};
+
+extern int generic_fsinfo(struct dentry *, struct fsinfo_kparams *);
+
+static inline void fsinfo_set_cap(struct fsinfo_capabilities *c,
+ enum fsinfo_capability cap)
+{
+ c->capabilities[cap / 8] |= 1 << (cap % 8);
+}
+
+static inline void fsinfo_clear_cap(struct fsinfo_capabilities *c,
+ enum fsinfo_capability cap)
+{
+ c->capabilities[cap / 8] &= ~(1 << (cap % 8));
+}
+
+#endif /* _LINUX_FSINFO_H */
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index ac803f5c0822..da3575dded79 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -49,6 +49,7 @@ struct stat64;
struct statfs;
struct statfs64;
struct statx;
+struct fsinfo_params;
struct __sysctl_args;
struct sysinfo;
struct timespec;
@@ -907,6 +908,9 @@ asmlinkage long sys_move_mount(int from_dfd, const char __user *from_path,
asmlinkage long sys_fsopen(const char __user *fs_name, unsigned int flags);
asmlinkage long sys_fsmount(int fs_fd, unsigned int flags, unsigned int ms_flags);
asmlinkage long sys_fspick(int dfd, const char __user *path, unsigned int flags);
+asmlinkage long sys_fsinfo(int dfd, const char __user *path,
+ struct fsinfo_params __user *params,
+ void __user *buffer, size_t buf_size);
/*
* Architecture-specific system calls
diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
new file mode 100644
index 000000000000..f2bc5130544d
--- /dev/null
+++ b/include/uapi/linux/fsinfo.h
@@ -0,0 +1,237 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* fsinfo() definitions.
+ *
+ * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#ifndef _UAPI_LINUX_FSINFO_H
+#define _UAPI_LINUX_FSINFO_H
+
+#include <linux/types.h>
+#include <linux/socket.h>
+
+/*
+ * The filesystem attributes that can be requested. Note that some attributes
+ * may have multiple instances which can be switched in the parameter block.
+ */
+enum fsinfo_attribute {
+ fsinfo_attr_statfs = 0, /* statfs()-style state */
+ fsinfo_attr_fsinfo = 1, /* Information about fsinfo() */
+ fsinfo_attr_ids = 2, /* Filesystem IDs */
+ fsinfo_attr_limits = 3, /* Filesystem limits */
+ fsinfo_attr_supports = 4, /* What's supported in statx, iocflags, ... */
+ fsinfo_attr_capabilities = 5, /* Filesystem capabilities (bits) */
+ fsinfo_attr_timestamp_info = 6, /* Inode timestamp info */
+ fsinfo_attr_volume_id = 7, /* Volume ID (string) */
+ fsinfo_attr_volume_uuid = 8, /* Volume UUID (LE uuid) */
+ fsinfo_attr_volume_name = 9, /* Volume name (string) */
+ fsinfo_attr_cell_name = 10, /* Cell name (string) */
+ fsinfo_attr_domain_name = 11, /* Domain name (string) */
+ fsinfo_attr_realm_name = 12, /* Realm name (string) */
+ fsinfo_attr_server_name = 13, /* Name of the Nth server */
+ fsinfo_attr_server_address = 14, /* Mth address of the Nth server */
+ fsinfo_attr_parameter = 15, /* Nth mount parameter (string) */
+ fsinfo_attr_source = 16, /* Nth mount source name (string) */
+ fsinfo_attr_name_encoding = 17, /* Filename encoding (string) */
+ fsinfo_attr_name_codepage = 18, /* Filename codepage (string) */
+ fsinfo_attr_io_size = 19, /* Optimal I/O sizes */
+ fsinfo_attr__nr
+};
+
+/*
+ * Optional fsinfo() parameter structure.
+ *
+ * If this is not given, it is assumed that fsinfo_attr_statfs instance 0,0 is
+ * desired.
+ */
+struct fsinfo_params {
+ __u32 at_flags; /* AT_SYMLINK_NOFOLLOW and similar flags */
+ __u32 request; /* What is being asking for (enum fsinfo_attribute) */
+ __u32 Nth; /* Instance of it (some may have multiple) */
+ __u32 Mth; /* Subinstance of Nth instance */
+ __u32 __reserved[6]; /* Reserved params; all must be 0 */
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_statfs).
+ * - This gives extended filesystem information.
+ */
+struct fsinfo_statfs {
+ __u64 f_blocks; /* Total number of blocks in fs */
+ __u64 f_bfree; /* Total number of free blocks */
+ __u64 f_bavail; /* Number of free blocks available to ordinary user */
+ __u64 f_files; /* Total number of file nodes in fs */
+ __u64 f_ffree; /* Number of free file nodes */
+ __u64 f_favail; /* Number of free file nodes available to ordinary user */
+ __u32 f_bsize; /* Optimal block size */
+ __u32 f_frsize; /* Fragment size */
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_ids).
+ *
+ * List of basic identifiers as is normally found in statfs().
+ */
+struct fsinfo_ids {
+ char f_fs_name[15 + 1];
+ __u64 f_flags; /* Filesystem mount flags (MS_*) */
+ __u64 f_fsid; /* Short 64-bit Filesystem ID (as statfs) */
+ __u64 f_sb_id; /* Internal superblock ID for sbnotify()/mntnotify() */
+ __u32 f_fstype; /* Filesystem type from linux/magic.h [uncond] */
+ __u32 f_dev_major; /* As st_dev_* from struct statx [uncond] */
+ __u32 f_dev_minor;
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_limits).
+ *
+ * List of supported filesystem limits.
+ */
+struct fsinfo_limits {
+ __u64 max_file_size; /* Maximum file size */
+ __u64 max_uid; /* Maximum UID supported */
+ __u64 max_gid; /* Maximum GID supported */
+ __u64 max_projid; /* Maximum project ID supported */
+ __u32 max_dev_major; /* Maximum device major representable */
+ __u32 max_dev_minor; /* Maximum device minor representable */
+ __u32 max_hard_links; /* Maximum number of hard links on a file */
+ __u32 max_xattr_body_len; /* Maximum xattr content length */
+ __u32 max_xattr_name_len; /* Maximum xattr name length */
+ __u32 max_filename_len; /* Maximum filename length */
+ __u32 max_symlink_len; /* Maximum symlink content length */
+ __u32 __reserved[1];
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_supports).
+ *
+ * What's supported in various masks, such as statx() attribute and mask bits
+ * and IOC flags.
+ */
+struct fsinfo_supports {
+ __u64 stx_attributes; /* What statx::stx_attributes are supported */
+ __u32 stx_mask; /* What statx::stx_mask bits are supported */
+ __u32 ioc_flags; /* What FS_IOC_* flags are supported */
+ __u32 win_file_attrs; /* What DOS/Windows FILE_* attributes are supported */
+ __u32 __reserved[1];
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_capabilities).
+ *
+ * Bitmask indicating filesystem capabilities where renderable as single bits.
+ */
+enum fsinfo_capability {
+ fsinfo_cap_is_kernel_fs = 0, /* fs is kernel-special filesystem */
+ fsinfo_cap_is_block_fs = 1, /* fs is block-based filesystem */
+ fsinfo_cap_is_flash_fs = 2, /* fs is flash filesystem */
+ fsinfo_cap_is_network_fs = 3, /* fs is network filesystem */
+ fsinfo_cap_is_automounter_fs = 4, /* fs is automounter special filesystem */
+ fsinfo_cap_automounts = 5, /* fs supports automounts */
+ fsinfo_cap_adv_locks = 6, /* fs supports advisory file locking */
+ fsinfo_cap_mand_locks = 7, /* fs supports mandatory file locking */
+ fsinfo_cap_leases = 8, /* fs supports file leases */
+ fsinfo_cap_uids = 9, /* fs supports numeric uids */
+ fsinfo_cap_gids = 10, /* fs supports numeric gids */
+ fsinfo_cap_projids = 11, /* fs supports numeric project ids */
+ fsinfo_cap_id_names = 12, /* fs supports user names */
+ fsinfo_cap_id_guids = 13, /* fs supports user guids */
+ fsinfo_cap_windows_attrs = 14, /* fs has windows attributes */
+ fsinfo_cap_user_quotas = 15, /* fs has per-user quotas */
+ fsinfo_cap_group_quotas = 16, /* fs has per-group quotas */
+ fsinfo_cap_project_quotas = 17, /* fs has per-project quotas */
+ fsinfo_cap_xattrs = 18, /* fs has xattrs */
+ fsinfo_cap_journal = 19, /* fs has a journal */
+ fsinfo_cap_data_is_journalled = 20, /* fs is using data journalling */
+ fsinfo_cap_o_sync = 21, /* fs supports O_SYNC */
+ fsinfo_cap_o_direct = 22, /* fs supports O_DIRECT */
+ fsinfo_cap_volume_id = 23, /* fs has a volume ID */
+ fsinfo_cap_volume_uuid = 24, /* fs has a volume UUID */
+ fsinfo_cap_volume_name = 25, /* fs has a volume name */
+ fsinfo_cap_volume_fsid = 26, /* fs has a volume FSID */
+ fsinfo_cap_cell_name = 27, /* fs has a cell name */
+ fsinfo_cap_domain_name = 28, /* fs has a domain name */
+ fsinfo_cap_realm_name = 29, /* fs has a realm name */
+ fsinfo_cap_iver_all_change = 30, /* i_version represents data + meta changes */
+ fsinfo_cap_iver_data_change = 31, /* i_version represents data changes only */
+ fsinfo_cap_iver_mono_incr = 32, /* i_version incremented monotonically */
+ fsinfo_cap_symlinks = 33, /* fs supports symlinks */
+ fsinfo_cap_hard_links = 34, /* fs supports hard links */
+ fsinfo_cap_hard_links_1dir = 35, /* fs supports hard links in same dir only */
+ fsinfo_cap_device_files = 36, /* fs supports bdev, cdev */
+ fsinfo_cap_unix_specials = 37, /* fs supports pipe, fifo, socket */
+ fsinfo_cap_resource_forks = 38, /* fs supports resource forks/streams */
+ fsinfo_cap_name_case_indep = 39, /* Filename case independence is mandatory */
+ fsinfo_cap_name_non_utf8 = 40, /* fs has non-utf8 names */
+ fsinfo_cap_name_has_codepage = 41, /* fs has a filename codepage */
+ fsinfo_cap_sparse = 42, /* fs supports sparse files */
+ fsinfo_cap_not_persistent = 43, /* fs is not persistent */
+ fsinfo_cap_no_unix_mode = 44, /* fs does not support unix mode bits */
+ fsinfo_cap_has_atime = 45, /* fs supports access time */
+ fsinfo_cap_has_btime = 46, /* fs supports birth/creation time */
+ fsinfo_cap_has_ctime = 47, /* fs supports change time */
+ fsinfo_cap_has_mtime = 48, /* fs supports modification time */
+ fsinfo_cap__nr
+};
+
+struct fsinfo_capabilities {
+ __u8 capabilities[(fsinfo_cap__nr + 7) / 8];
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_timestamp_info).
+ */
+struct fsinfo_timestamp_info {
+ __s64 minimum_timestamp; /* Minimum timestamp value in seconds */
+ __s64 maximum_timestamp; /* Maximum timestamp value in seconds */
+ __u16 atime_gran_mantissa; /* Granularity(secs) = mant * 10^exp */
+ __u16 btime_gran_mantissa;
+ __u16 ctime_gran_mantissa;
+ __u16 mtime_gran_mantissa;
+ __s8 atime_gran_exponent;
+ __s8 btime_gran_exponent;
+ __s8 ctime_gran_exponent;
+ __s8 mtime_gran_exponent;
+ __u32 __reserved[1];
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_volume_uuid).
+ */
+struct fsinfo_volume_uuid {
+ __u8 uuid[16];
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_server_addresses).
+ *
+ * Find the Mth address of the Nth server for a network mount.
+ */
+struct fsinfo_server_address {
+ struct __kernel_sockaddr_storage address;
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_io_size).
+ *
+ * Retrieve the optimal I/O size for a filesystem.
+ */
+struct fsinfo_io_size {
+ __u32 block_size; /* Minimum block granularity for O_DIRECT */
+ __u32 max_single_read_size; /* Maximum size of a single unbuffered read */
+ __u32 max_single_write_size; /* Maximum size of a single unbuffered write */
+ __u32 best_read_size; /* Optimal read size */
+ __u32 best_write_size; /* Optimal write size */
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_fsinfo).
+ *
+ * This gives information about fsinfo() itself.
+ */
+struct fsinfo_fsinfo {
+ __u32 max_attr; /* Number of supported attributes (fsinfo_attr__nr) */
+ __u32 max_cap; /* Number of supported capabilities (fsinfo_cap__nr) */
+};
+
+#endif /* _UAPI_LINUX_FSINFO_H */
diff --git a/samples/statx/Makefile b/samples/statx/Makefile
index 59df7c25a9d1..9cb9a88e3a10 100644
--- a/samples/statx/Makefile
+++ b/samples/statx/Makefile
@@ -1,7 +1,10 @@
# List of programs to build
-hostprogs-$(CONFIG_SAMPLE_STATX) := test-statx
+hostprogs-$(CONFIG_SAMPLE_STATX) := test-statx test-fsinfo
# Tell kbuild to always build the programs
always := $(hostprogs-y)
HOSTCFLAGS_test-statx.o += -I$(objtree)/usr/include
+
+HOSTCFLAGS_test-fsinfo.o += -I$(objtree)/usr/include
+HOSTLOADLIBES_test-fsinfo += -lm
diff --git a/samples/statx/test-fsinfo.c b/samples/statx/test-fsinfo.c
new file mode 100644
index 000000000000..9e9fa62a3b9f
--- /dev/null
+++ b/samples/statx/test-fsinfo.c
@@ -0,0 +1,539 @@
+/* Test the fsinfo() system call
+ *
+ * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define _GNU_SOURCE
+#define _ATFILE_SOURCE
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <errno.h>
+#include <time.h>
+#include <math.h>
+#include <fcntl.h>
+#include <sys/syscall.h>
+#include <linux/fsinfo.h>
+#include <linux/socket.h>
+#include <sys/stat.h>
+
+static __attribute__((unused))
+ssize_t fsinfo(int dfd, const char *filename, struct fsinfo_params *params,
+ void *buffer, size_t buf_size)
+{
+ return syscall(__NR_fsinfo, dfd, filename, params, buffer, buf_size);
+}
+
+#define FSINFO_STRING(N) [fsinfo_attr_##N] = 0x00
+#define FSINFO_STRUCT(N) [fsinfo_attr_##N] = sizeof(struct fsinfo_##N)/sizeof(__u32)
+#define FSINFO_STRING_N(N) [fsinfo_attr_##N] = 0x40
+#define FSINFO_STRUCT_N(N) [fsinfo_attr_##N] = 0x40 | sizeof(struct fsinfo_##N)/sizeof(__u32)
+#define FSINFO_STRUCT_NM(N) [fsinfo_attr_##N] = 0x80 | sizeof(struct fsinfo_##N)/sizeof(__u32)
+static const __u8 fsinfo_buffer_sizes[fsinfo_attr__nr] = {
+ FSINFO_STRUCT (statfs),
+ FSINFO_STRUCT (fsinfo),
+ FSINFO_STRUCT (ids),
+ FSINFO_STRUCT (limits),
+ FSINFO_STRUCT (supports),
+ FSINFO_STRUCT (capabilities),
+ FSINFO_STRUCT (timestamp_info),
+ FSINFO_STRING (volume_id),
+ FSINFO_STRUCT (volume_uuid),
+ FSINFO_STRING (volume_name),
+ FSINFO_STRING (cell_name),
+ FSINFO_STRING (domain_name),
+ FSINFO_STRING (realm_name),
+ FSINFO_STRING_N (server_name),
+ FSINFO_STRUCT_NM (server_address),
+ FSINFO_STRING_N (parameter),
+ FSINFO_STRING_N (source),
+ FSINFO_STRING (name_encoding),
+ FSINFO_STRING (name_codepage),
+ FSINFO_STRUCT (io_size),
+};
+
+#define FSINFO_NAME(N) [fsinfo_attr_##N] = #N
+static const char *fsinfo_attr_names[fsinfo_attr__nr] = {
+ FSINFO_NAME(statfs),
+ FSINFO_NAME(fsinfo),
+ FSINFO_NAME(ids),
+ FSINFO_NAME(limits),
+ FSINFO_NAME(supports),
+ FSINFO_NAME(capabilities),
+ FSINFO_NAME(timestamp_info),
+ FSINFO_NAME(volume_id),
+ FSINFO_NAME(volume_uuid),
+ FSINFO_NAME(volume_name),
+ FSINFO_NAME(cell_name),
+ FSINFO_NAME(domain_name),
+ FSINFO_NAME(realm_name),
+ FSINFO_NAME(server_name),
+ FSINFO_NAME(server_address),
+ FSINFO_NAME(parameter),
+ FSINFO_NAME(source),
+ FSINFO_NAME(name_encoding),
+ FSINFO_NAME(name_codepage),
+ FSINFO_NAME(io_size),
+};
+
+union reply {
+ char buffer[4096];
+ struct fsinfo_statfs statfs;
+ struct fsinfo_fsinfo fsinfo;
+ struct fsinfo_ids ids;
+ struct fsinfo_limits limits;
+ struct fsinfo_supports supports;
+ struct fsinfo_capabilities caps;
+ struct fsinfo_timestamp_info timestamps;
+ struct fsinfo_volume_uuid uuid;
+ struct fsinfo_server_address srv_addr;
+ struct fsinfo_io_size io_size;
+};
+
+static void dump_hex(unsigned int *data, int from, int to)
+{
+ unsigned offset, print_offset = 1, col = 0;
+
+ from /= 4;
+ to = (to + 3) / 4;
+
+ for (offset = from; offset < to; offset++) {
+ if (print_offset) {
+ printf("%04x: ", offset * 8);
+ print_offset = 0;
+ }
+ printf("%08x", data[offset]);
+ col++;
+ if ((col & 3) == 0) {
+ printf("\n");
+ print_offset = 1;
+ } else {
+ printf(" ");
+ }
+ }
+
+ if (!print_offset)
+ printf("\n");
+}
+
+static void dump_attr_statfs(union reply *r, int size)
+{
+ struct fsinfo_statfs *f = &r->statfs;
+
+ printf("\n");
+ printf("\tblocks: n=%llu fr=%llu av=%llu\n",
+ (unsigned long long)f->f_blocks,
+ (unsigned long long)f->f_bfree,
+ (unsigned long long)f->f_bavail);
+
+ printf("\tfiles : n=%llu fr=%llu av=%llu\n",
+ (unsigned long long)f->f_files,
+ (unsigned long long)f->f_ffree,
+ (unsigned long long)f->f_favail);
+ printf("\tbsize : %u\n", f->f_bsize);
+ printf("\tfrsize: %u\n", f->f_frsize);
+}
+
+static void dump_attr_fsinfo(union reply *r, int size)
+{
+ struct fsinfo_fsinfo *f = &r->fsinfo;
+
+ printf("max_attr=%u max_cap=%u\n", f->max_attr, f->max_cap);
+}
+
+static void dump_attr_ids(union reply *r, int size)
+{
+ struct fsinfo_ids *f = &r->ids;
+
+ printf("\n");
+ printf("\tdev : %02x:%02x\n", f->f_dev_major, f->f_dev_minor);
+ printf("\tfs : type=%x name=%s\n", f->f_fstype, f->f_fs_name);
+ printf("\tflags : %llx\n", (unsigned long long)f->f_flags);
+ printf("\tfsid : %llx\n", (unsigned long long)f->f_fsid);
+}
+
+static void dump_attr_limits(union reply *r, int size)
+{
+ struct fsinfo_limits *f = &r->limits;
+
+ printf("\n");
+ printf("\tmax file size: %llx\n", f->max_file_size);
+ printf("\tmax ids : u=%llx g=%llx p=%llx\n",
+ f->max_uid, f->max_gid, f->max_projid);
+ printf("\tmax dev : maj=%x min=%x\n",
+ f->max_dev_major, f->max_dev_minor);
+ printf("\tmax links : %x\n", f->max_hard_links);
+ printf("\tmax xattr : n=%x b=%x\n",
+ f->max_xattr_name_len, f->max_xattr_body_len);
+ printf("\tmax len : file=%x sym=%x\n",
+ f->max_filename_len, f->max_symlink_len);
+}
+
+static void dump_attr_supports(union reply *r, int size)
+{
+ struct fsinfo_supports *f = &r->supports;
+
+ printf("\n");
+ printf("\tstx_attr=%llx\n", f->stx_attributes);
+ printf("\tstx_mask=%x\n", f->stx_mask);
+ printf("\tioc_flags=%x\n", f->ioc_flags);
+ printf("\twin_fattrs=%x\n", f->win_file_attrs);
+}
+
+#define FSINFO_CAP_NAME(C) [fsinfo_cap_##C] = #C
+static const char *fsinfo_cap_names[fsinfo_cap__nr] = {
+ FSINFO_CAP_NAME(is_kernel_fs),
+ FSINFO_CAP_NAME(is_block_fs),
+ FSINFO_CAP_NAME(is_flash_fs),
+ FSINFO_CAP_NAME(is_network_fs),
+ FSINFO_CAP_NAME(is_automounter_fs),
+ FSINFO_CAP_NAME(automounts),
+ FSINFO_CAP_NAME(adv_locks),
+ FSINFO_CAP_NAME(mand_locks),
+ FSINFO_CAP_NAME(leases),
+ FSINFO_CAP_NAME(uids),
+ FSINFO_CAP_NAME(gids),
+ FSINFO_CAP_NAME(projids),
+ FSINFO_CAP_NAME(id_names),
+ FSINFO_CAP_NAME(id_guids),
+ FSINFO_CAP_NAME(windows_attrs),
+ FSINFO_CAP_NAME(user_quotas),
+ FSINFO_CAP_NAME(group_quotas),
+ FSINFO_CAP_NAME(project_quotas),
+ FSINFO_CAP_NAME(xattrs),
+ FSINFO_CAP_NAME(journal),
+ FSINFO_CAP_NAME(data_is_journalled),
+ FSINFO_CAP_NAME(o_sync),
+ FSINFO_CAP_NAME(o_direct),
+ FSINFO_CAP_NAME(volume_id),
+ FSINFO_CAP_NAME(volume_uuid),
+ FSINFO_CAP_NAME(volume_name),
+ FSINFO_CAP_NAME(volume_fsid),
+ FSINFO_CAP_NAME(cell_name),
+ FSINFO_CAP_NAME(domain_name),
+ FSINFO_CAP_NAME(realm_name),
+ FSINFO_CAP_NAME(iver_all_change),
+ FSINFO_CAP_NAME(iver_data_change),
+ FSINFO_CAP_NAME(iver_mono_incr),
+ FSINFO_CAP_NAME(symlinks),
+ FSINFO_CAP_NAME(hard_links),
+ FSINFO_CAP_NAME(hard_links_1dir),
+ FSINFO_CAP_NAME(device_files),
+ FSINFO_CAP_NAME(unix_specials),
+ FSINFO_CAP_NAME(resource_forks),
+ FSINFO_CAP_NAME(name_case_indep),
+ FSINFO_CAP_NAME(name_non_utf8),
+ FSINFO_CAP_NAME(name_has_codepage),
+ FSINFO_CAP_NAME(sparse),
+ FSINFO_CAP_NAME(not_persistent),
+ FSINFO_CAP_NAME(no_unix_mode),
+ FSINFO_CAP_NAME(has_atime),
+ FSINFO_CAP_NAME(has_btime),
+ FSINFO_CAP_NAME(has_ctime),
+ FSINFO_CAP_NAME(has_mtime),
+};
+
+static void dump_attr_capabilities(union reply *r, int size)
+{
+ struct fsinfo_capabilities *f = &r->caps;
+ int i;
+
+ for (i = 0; i < sizeof(f->capabilities); i++)
+ printf("%02x", f->capabilities[i]);
+ printf("\n");
+ for (i = 0; i < fsinfo_cap__nr; i++)
+ if (f->capabilities[i / 8] & (1 << (i % 8)))
+ printf("\t- %s\n", fsinfo_cap_names[i]);
+}
+
+static void dump_attr_timestamp_info(union reply *r, int size)
+{
+ struct fsinfo_timestamp_info *f = &r->timestamps;
+
+ printf("range=%llx-%llx\n",
+ (unsigned long long)f->minimum_timestamp,
+ (unsigned long long)f->maximum_timestamp);
+
+#define print_time(G) \
+ printf("\t"#G"time : gran=%gs\n", \
+ (f->G##time_gran_mantissa * \
+ pow(10., f->G##time_gran_exponent)))
+ print_time(a);
+ print_time(b);
+ print_time(c);
+ print_time(m);
+}
+
+static void dump_attr_volume_uuid(union reply *r, int size)
+{
+ struct fsinfo_volume_uuid *f = &r->uuid;
+
+ printf("%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x"
+ "-%02x%02x%02x%02x%02x%02x\n",
+ f->uuid[ 0], f->uuid[ 1],
+ f->uuid[ 2], f->uuid[ 3],
+ f->uuid[ 4], f->uuid[ 5],
+ f->uuid[ 6], f->uuid[ 7],
+ f->uuid[ 8], f->uuid[ 9],
+ f->uuid[10], f->uuid[11],
+ f->uuid[12], f->uuid[13],
+ f->uuid[14], f->uuid[15]);
+}
+
+static void dump_attr_server_address(union reply *r, int size)
+{
+ struct fsinfo_server_address *f = &r->srv_addr;
+
+ printf("family=%u\n", f->address.ss_family);
+}
+
+static void dump_attr_io_size(union reply *r, int size)
+{
+ struct fsinfo_io_size *f = &r->io_size;
+
+ printf("bs=%u\n", f->block_size);
+}
+
+/*
+ *
+ */
+typedef void (*dumper_t)(union reply *r, int size);
+
+#define FSINFO_DUMPER(N) [fsinfo_attr_##N] = dump_attr_##N
+static const dumper_t fsinfo_attr_dumper[fsinfo_attr__nr] = {
+ FSINFO_DUMPER(statfs),
+ FSINFO_DUMPER(fsinfo),
+ FSINFO_DUMPER(ids),
+ FSINFO_DUMPER(limits),
+ FSINFO_DUMPER(supports),
+ FSINFO_DUMPER(capabilities),
+ FSINFO_DUMPER(timestamp_info),
+ FSINFO_DUMPER(volume_uuid),
+ FSINFO_DUMPER(server_address),
+ FSINFO_DUMPER(io_size),
+};
+
+static void dump_fsinfo(enum fsinfo_attribute attr, __u8 about,
+ union reply *r, int size)
+{
+ dumper_t dumper = fsinfo_attr_dumper[attr];
+ unsigned int len;
+
+ if (!dumper) {
+ printf("<no dumper>\n");
+ return;
+ }
+
+ len = (about & 0x3f) * sizeof(__u32);
+ if (size < len) {
+ printf("<short data %u/%u>\n", size, len);
+ return;
+ }
+
+ dumper(r, size);
+}
+
+/*
+ * Try one subinstance of an attribute.
+ */
+static int try_one(const char *file, struct fsinfo_params *params, bool raw)
+{
+ union reply r;
+ char *p;
+ int ret;
+ __u8 about;
+
+ memset(&r.buffer, 0xbd, sizeof(r.buffer));
+
+ errno = 0;
+ ret = fsinfo(AT_FDCWD, file, params, r.buffer, sizeof(r.buffer));
+ if (params->request >= fsinfo_attr__nr) {
+ if (ret == -1 && errno == EOPNOTSUPP)
+ exit(0);
+ fprintf(stderr, "Unexpected error for too-large command %u: %m\n",
+ params->request);
+ exit(1);
+ }
+
+ //printf("fsinfo(%s,%s,%u,%u) = %d: %m\n",
+ // file, fsinfo_attr_names[params->request],
+ // params->Nth, params->Mth, ret);
+
+ about = fsinfo_buffer_sizes[params->request];
+ if (ret == -1) {
+ if (errno == ENODATA) {
+ switch (about & 0xc0) {
+ case 0x00:
+ if (params->Nth == 0 && params->Mth == 0) {
+ fprintf(stderr,
+ "Unexpected ENODATA1 (%u[%u][%u])\n",
+ params->request, params->Nth, params->Mth);
+ exit(1);
+ }
+ break;
+ case 0x40:
+ if (params->Nth == 0 && params->Mth == 0) {
+ fprintf(stderr,
+ "Unexpected ENODATA2 (%u[%u][%u])\n",
+ params->request, params->Nth, params->Mth);
+ exit(1);
+ }
+ break;
+ }
+ return (params->Mth == 0) ? 2 : 1;
+ }
+ if (errno == EOPNOTSUPP) {
+ if (params->Nth > 0 || params->Mth > 0) {
+ fprintf(stderr,
+ "Should return -ENODATA (%u[%u][%u])\n",
+ params->request, params->Nth, params->Mth);
+ exit(1);
+ }
+ //printf("\e[33m%s\e[m: <not supported>\n",
+ // fsinfo_attr_names[attr]);
+ return 2;
+ }
+ perror(file);
+ exit(1);
+ }
+
+ if (raw) {
+ if (ret > 4096)
+ ret = 4096;
+ dump_hex((unsigned int *)&r.buffer, 0, ret);
+ return 0;
+ }
+
+ switch (about & 0xc0) {
+ case 0x00:
+ printf("\e[33m%s\e[m: ",
+ fsinfo_attr_names[params->request]);
+ break;
+ case 0x40:
+ printf("\e[33m%s[%u]\e[m: ",
+ fsinfo_attr_names[params->request],
+ params->Nth);
+ break;
+ case 0x80:
+ printf("\e[33m%s[%u][%u]\e[m: ",
+ fsinfo_attr_names[params->request],
+ params->Nth, params->Mth);
+ break;
+ }
+
+ switch (about) {
+ /* Struct */
+ case 0x01 ... 0x3f:
+ case 0x41 ... 0x7f:
+ case 0x81 ... 0xbf:
+ dump_fsinfo(params->request, about, &r, ret);
+ return 0;
+
+ /* String */
+ case 0x00:
+ case 0x40:
+ case 0x80:
+ if (ret >= 4096) {
+ ret = 4096;
+ r.buffer[4092] = '.';
+ r.buffer[4093] = '.';
+ r.buffer[4094] = '.';
+ r.buffer[4095] = 0;
+ } else {
+ r.buffer[ret] = 0;
+ }
+ for (p = r.buffer; *p; p++) {
+ if (!isprint(*p)) {
+ printf("<non-printable>\n");
+ continue;
+ }
+ }
+ printf("%s\n", r.buffer);
+ return 0;
+
+ default:
+ fprintf(stderr, "Fishy about %u %02x\n", params->request, about);
+ exit(1);
+ }
+}
+
+/*
+ *
+ */
+int main(int argc, char **argv)
+{
+ struct fsinfo_params params = {
+ .at_flags = AT_SYMLINK_NOFOLLOW,
+ };
+ unsigned int attr;
+ int raw = 0, opt, Nth, Mth;
+
+ while ((opt = getopt(argc, argv, "alr"))) {
+ switch (opt) {
+ case 'a':
+ params.at_flags |= AT_NO_AUTOMOUNT;
+ continue;
+ case 'l':
+ params.at_flags &= ~AT_SYMLINK_NOFOLLOW;
+ continue;
+ case 'r':
+ raw = 1;
+ continue;
+ }
+ break;
+ }
+
+ argc -= optind;
+ argv += optind;
+
+ if (argc != 1) {
+ printf("Format: test-fsinfo [-alr] <file>\n");
+ exit(2);
+ }
+
+ for (attr = 0; attr <= fsinfo_attr__nr; attr++) {
+ Nth = 0;
+ do {
+ Mth = 0;
+ do {
+ params.request = attr;
+ params.Nth = Nth;
+ params.Mth = Mth;
+
+ switch (try_one(argv[0], ¶ms, raw)) {
+ case 0:
+ continue;
+ case 1:
+ goto done_M;
+ case 2:
+ goto done_N;
+ }
+ } while (++Mth < 100);
+
+ done_M:
+ if (Mth >= 100) {
+ fprintf(stderr, "Fishy: Mth == %u\n", Mth);
+ break;
+ }
+
+ } while (++Nth < 100);
+
+ done_N:
+ if (Nth >= 100) {
+ fprintf(stderr, "Fishy: Nth == %u\n", Nth);
+ break;
+ }
+ }
+
+ return 0;
+}
^ permalink raw reply related
* Re: [RFC PATCH v2 11/27] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW
From: Dave Hansen @ 2018-07-10 22:44 UTC (permalink / raw)
To: Yu-cheng Yu, x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar,
linux-kernel, linux-doc, linux-mm, linux-arch, linux-api,
Arnd Bergmann, Andy Lutomirski, Balbir Singh, Cyrill Gorcunov,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek,
Peter Zijlstra <pet>
In-Reply-To: <20180710222639.8241-12-yu-cheng.yu@intel.com>
On 07/10/2018 03:26 PM, Yu-cheng Yu wrote:
> + /*
> + * On platforms before CET, other threads could race to
> + * create a RO and _PAGE_DIRTY_HW PMD again. However,
> + * on CET platforms, this is safe without a TLB flush.
> + */
If I didn't work for Intel, I'd wonder what the heck CET is and what the
heck it has to do with _PAGE_DIRTY_HW. I think we need a better comment
than this. How about:
Some processors can _start_ a write, but end up seeing
a read-only PTE by the time they get to getting the
Dirty bit. In this case, they will set the Dirty bit,
leaving a read-only, Dirty PTE which looks like a Shadow
Stack PTE.
However, this behavior has been improved and will *not* occur on
processors supporting Shadow Stacks. Without this guarantee, a
transition to a non-present PTE and flush the TLB would be
needed.
^ permalink raw reply
* [PATCH 26/32] vfs: syscall: Add fspick() to select a superblock for reconfiguration [ver #9]
From: David Howells @ 2018-07-10 22:44 UTC (permalink / raw)
To: viro; +Cc: dhowells, linux-api, linux-fsdevel, torvalds, linux-kernel
In-Reply-To: <153126248868.14533.9751473662727327569.stgit@warthog.procyon.org.uk>
Provide an fspick() system call that can be used to pick an existing
mountpoint into an fs_context which can thereafter be used to reconfigure a
superblock (equivalent of the superblock side of -o remount).
This looks like:
int fd = fspick(AT_FDCWD, "/mnt",
FSPICK_CLOEXEC | FSPICK_NO_AUTOMOUNT);
write(fd, "o intr");
write(fd, "o noac");
write(fd, "x reconfigure");
At the point of fspick being called, the file descriptor referring to the
filesystem context is in exactly the same state as the one that was created
by fsopen() after fsmount() has been successfully called.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-api@vger.kernel.org
---
arch/x86/entry/syscalls/syscall_32.tbl | 1 +
arch/x86/entry/syscalls/syscall_64.tbl | 1 +
fs/fsopen.c | 53 ++++++++++++++++++++++++++++++++
include/linux/syscalls.h | 1 +
include/uapi/linux/fs.h | 5 +++
5 files changed, 61 insertions(+)
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 537572098032..5587bcede253 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -402,3 +402,4 @@
388 i386 move_mount sys_move_mount __ia32_sys_move_mount
389 i386 fsopen sys_fsopen __ia32_sys_fsopen
390 i386 fsmount sys_fsmount __ia32_sys_fsmount
+391 i386 fspick sys_fspick __ia32_sys_fspick
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 47abbc2a2bbe..460a464024bf 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -347,6 +347,7 @@
336 common move_mount __x64_sys_move_mount
337 common fsopen __x64_sys_fsopen
338 common fsmount __x64_sys_fsmount
+339 common fspick __x64_sys_fspick
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/fsopen.c b/fs/fsopen.c
index 28bb72bda163..35c2a94d0c68 100644
--- a/fs/fsopen.c
+++ b/fs/fsopen.c
@@ -15,6 +15,7 @@
#include <linux/syscalls.h>
#include <linux/security.h>
#include <linux/anon_inodes.h>
+#include <linux/namei.h>
#include "mount.h"
/*
@@ -207,3 +208,55 @@ SYSCALL_DEFINE2(fsopen, const char __user *, _fs_name, unsigned int, flags)
fc->phase = FS_CONTEXT_CREATE_PARAMS;
return fscontext_create_fd(fc, flags & FSOPEN_CLOEXEC ? O_CLOEXEC : 0);
}
+
+/*
+ * Pick a superblock into a context for reconfiguration.
+ */
+SYSCALL_DEFINE3(fspick, int, dfd, const char __user *, path, unsigned int, flags)
+{
+ struct fs_context *fc;
+ struct path target;
+ unsigned int lookup_flags;
+ int ret;
+
+ if (!ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if ((flags & ~(FSPICK_CLOEXEC |
+ FSPICK_SYMLINK_NOFOLLOW |
+ FSPICK_NO_AUTOMOUNT |
+ FSPICK_EMPTY_PATH)) != 0)
+ return -EINVAL;
+
+ lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
+ if (flags & FSPICK_SYMLINK_NOFOLLOW)
+ lookup_flags &= ~LOOKUP_FOLLOW;
+ if (flags & FSPICK_NO_AUTOMOUNT)
+ lookup_flags &= ~LOOKUP_AUTOMOUNT;
+ if (flags & FSPICK_EMPTY_PATH)
+ lookup_flags |= LOOKUP_EMPTY;
+ ret = user_path_at(dfd, path, lookup_flags, &target);
+ if (ret < 0)
+ goto err;
+
+ ret = -EOPNOTSUPP;
+ if (!target.dentry->d_sb->s_op->reconfigure)
+ goto err_path;
+
+ fc = vfs_new_fs_context(target.dentry->d_sb->s_type, target.dentry,
+ 0, FS_CONTEXT_FOR_RECONFIGURE);
+ if (IS_ERR(fc)) {
+ ret = PTR_ERR(fc);
+ goto err_path;
+ }
+
+ fc->phase = FS_CONTEXT_RECONF_PARAMS;
+
+ path_put(&target);
+ return fscontext_create_fd(fc, flags & FSPICK_CLOEXEC ? O_CLOEXEC : 0);
+
+err_path:
+ path_put(&target);
+err:
+ return ret;
+}
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 917fe10e1030..ac803f5c0822 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -906,6 +906,7 @@ asmlinkage long sys_move_mount(int from_dfd, const char __user *from_path,
unsigned int ms_flags);
asmlinkage long sys_fsopen(const char __user *fs_name, unsigned int flags);
asmlinkage long sys_fsmount(int fs_fd, unsigned int flags, unsigned int ms_flags);
+asmlinkage long sys_fspick(int dfd, const char __user *path, unsigned int flags);
/*
* Architecture-specific system calls
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 30a2fb85c4b7..c27576d471c2 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -351,4 +351,9 @@ typedef int __bitwise __kernel_rwf_t;
#define FSMOUNT_CLOEXEC 0x00000001
+#define FSPICK_CLOEXEC 0x00000001
+#define FSPICK_SYMLINK_NOFOLLOW 0x00000002
+#define FSPICK_NO_AUTOMOUNT 0x00000004
+#define FSPICK_EMPTY_PATH 0x00000008
+
#endif /* _UAPI_LINUX_FS_H */
^ permalink raw reply related
* [PATCH 25/32] vfs: syscall: Add fsmount() to create a mount for a superblock [ver #9]
From: David Howells @ 2018-07-10 22:44 UTC (permalink / raw)
To: viro; +Cc: dhowells, linux-api, linux-fsdevel, torvalds, linux-kernel
In-Reply-To: <153126248868.14533.9751473662727327569.stgit@warthog.procyon.org.uk>
Provide a system call by which a filesystem opened with fsopen() and
configured by a series of writes can be mounted:
int ret = fsmount(int fsfd, unsigned int flags,
unsigned int ms_flags);
where fsfd is the file descriptor returned by fsopen(). flags can be 0 or
FSMOUNT_CLOEXEC. ms_flags is a bitwise-OR of the following flags:
MS_RDONLY
MS_NOSUID
MS_NODEV
MS_NOEXEC
MS_NOATIME
MS_NODIRATIME
MS_RELATIME
MS_STRICTATIME
MS_UNBINDABLE
MS_PRIVATE
MS_SLAVE
MS_SHARED
In the event that fsmount() fails, it may be possible to get an error
message by calling read() on fsfd. If no message is available, ENODATA
will be reported.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-api@vger.kernel.org
---
arch/x86/entry/syscalls/syscall_32.tbl | 1
arch/x86/entry/syscalls/syscall_64.tbl | 1
fs/namespace.c | 140 +++++++++++++++++++++++++++++++-
include/linux/fs_context.h | 2
include/linux/syscalls.h | 1
include/uapi/linux/fs.h | 2
6 files changed, 143 insertions(+), 4 deletions(-)
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 1647fefd2969..537572098032 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -401,3 +401,4 @@
387 i386 open_tree sys_open_tree __ia32_sys_open_tree
388 i386 move_mount sys_move_mount __ia32_sys_move_mount
389 i386 fsopen sys_fsopen __ia32_sys_fsopen
+390 i386 fsmount sys_fsmount __ia32_sys_fsmount
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 235d33dbccb2..47abbc2a2bbe 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -346,6 +346,7 @@
335 common open_tree __x64_sys_open_tree
336 common move_mount __x64_sys_move_mount
337 common fsopen __x64_sys_fsopen
+338 common fsmount __x64_sys_fsmount
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/namespace.c b/fs/namespace.c
index d5a4d9351a17..a6fbfba8e448 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2503,7 +2503,7 @@ static int do_move_mount(struct path *old_path, struct path *new_path)
attached = mnt_has_parent(old);
/*
- * We need to allow open_tree(OPEN_TREE_CLONE) followed by
+ * We need to allow open_tree(OPEN_TREE_CLONE) or fsmount() followed by
* move_mount(), but mustn't allow "/" to be moved.
*/
if (old->mnt_ns && !attached)
@@ -3347,9 +3347,141 @@ struct vfsmount *kern_mount(struct file_system_type *type)
EXPORT_SYMBOL_GPL(kern_mount);
/*
- * Move a mount from one place to another.
- * In combination with open_tree(OPEN_TREE_CLONE [| AT_RECURSIVE]) it can be
- * used to copy a mount subtree.
+ * Create a kernel mount representation for a new, prepared superblock
+ * (specified by fs_fd) and attach to an open_tree-like file descriptor.
+ */
+SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags, unsigned int, ms_flags)
+{
+ struct fs_context *fc;
+ struct file *file;
+ struct path newmount;
+ struct fd f;
+ unsigned int mnt_flags = 0;
+ long ret;
+
+ if (!may_mount())
+ return -EPERM;
+
+ if ((flags & ~(FSMOUNT_CLOEXEC)) != 0)
+ return -EINVAL;
+
+ if (ms_flags & ~(MS_RDONLY | MS_NOSUID | MS_NODEV | MS_NOEXEC |
+ MS_NOATIME | MS_NODIRATIME | MS_RELATIME |
+ MS_STRICTATIME))
+ return -EINVAL;
+
+ if (ms_flags & MS_RDONLY)
+ mnt_flags |= MNT_READONLY;
+ if (ms_flags & MS_NOSUID)
+ mnt_flags |= MNT_NOSUID;
+ if (ms_flags & MS_NODEV)
+ mnt_flags |= MNT_NODEV;
+ if (ms_flags & MS_NOEXEC)
+ mnt_flags |= MNT_NOEXEC;
+ if (ms_flags & MS_NODIRATIME)
+ mnt_flags |= MNT_NODIRATIME;
+
+ if (ms_flags & MS_STRICTATIME) {
+ if (ms_flags & MS_NOATIME)
+ return -EINVAL;
+ } else if (ms_flags & MS_NOATIME) {
+ mnt_flags |= MNT_NOATIME;
+ } else {
+ mnt_flags |= MNT_RELATIME;
+ }
+
+ f = fdget(fs_fd);
+ if (!f.file)
+ return -EBADF;
+
+ ret = -EINVAL;
+ if (f.file->f_op != &fscontext_fs_fops)
+ goto err_fsfd;
+
+ fc = f.file->private_data;
+
+ /* There must be a valid superblock or we can't mount it */
+ ret = -EINVAL;
+ if (!fc->root)
+ goto err_fsfd;
+
+ ret = -EPERM;
+ if (mount_too_revealing(fc->root->d_sb, &mnt_flags)) {
+ pr_warn("VFS: Mount too revealing\n");
+ goto err_fsfd;
+ }
+
+ ret = mutex_lock_interruptible(&fc->uapi_mutex);
+ if (ret < 0)
+ goto err_fsfd;
+
+ ret = -EBUSY;
+ if (fc->phase != FS_CONTEXT_AWAITING_MOUNT)
+ goto err_unlock;
+
+ ret = -EPERM;
+ if ((fc->sb_flags & SB_MANDLOCK) && !may_mandlock())
+ goto err_unlock;
+
+ newmount.mnt = vfs_create_mount(fc, mnt_flags);
+ if (IS_ERR(newmount.mnt)) {
+ ret = PTR_ERR(newmount.mnt);
+ goto err_unlock;
+ }
+ newmount.dentry = dget(fc->root);
+
+ /* We've done the mount bit - now move the file context into more or
+ * less the same state as if we'd done an fspick(). We don't want to
+ * do any memory allocation or anything like that at this point as we
+ * don't want to have to handle any errors incurred.
+ */
+ if (fc->ops && fc->ops->free)
+ fc->ops->free(fc);
+ fc->fs_private = NULL;
+ fc->s_fs_info = NULL;
+ fc->sb_flags = 0;
+ fc->sloppy = false;
+ fc->silent = false;
+ security_fs_context_free(fc);
+ fc->security = NULL;
+ kfree(fc->subtype);
+ fc->subtype = NULL;
+ kfree(fc->source);
+ fc->source = NULL;
+
+ fc->purpose = FS_CONTEXT_FOR_RECONFIGURE;
+ fc->phase = FS_CONTEXT_AWAITING_RECONF;
+
+ /* Attach to an apparent O_PATH fd with a note that we need to unmount
+ * it, not just simply put it.
+ */
+ file = dentry_open(&newmount, O_PATH, fc->cred);
+ if (IS_ERR(file)) {
+ ret = PTR_ERR(file);
+ goto err_path;
+ }
+ file->f_mode |= FMODE_NEED_UNMOUNT;
+
+ ret = get_unused_fd_flags((flags & FSMOUNT_CLOEXEC) ? O_CLOEXEC : 0);
+ if (ret >= 0)
+ fd_install(ret, file);
+ else
+ fput(file);
+
+err_path:
+ path_put(&newmount);
+err_unlock:
+ mutex_unlock(&fc->uapi_mutex);
+err_fsfd:
+ fdput(f);
+ return ret;
+}
+
+/*
+ * Move a mount from one place to another. In combination with
+ * fsopen()/fsmount() this is used to install a new mount and in combination
+ * with open_tree(OPEN_TREE_CLONE [| AT_RECURSIVE]) it can be used to copy
+ * a mount subtree.
*
* Note the flags value is a combination of MOVE_MOUNT_* flags.
*/
diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h
index 387f25d7acc4..2cde97490c6f 100644
--- a/include/linux/fs_context.h
+++ b/include/linux/fs_context.h
@@ -115,4 +115,6 @@ extern int vfs_get_super(struct fs_context *fc,
int (*fill_super)(struct super_block *sb,
struct fs_context *fc));
+extern const struct file_operations fscontext_fs_fops;
+
#endif /* _LINUX_FS_CONTEXT_H */
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index ad6c7ff33c01..917fe10e1030 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -905,6 +905,7 @@ asmlinkage long sys_move_mount(int from_dfd, const char __user *from_path,
int to_dfd, const char __user *to_path,
unsigned int ms_flags);
asmlinkage long sys_fsopen(const char __user *fs_name, unsigned int flags);
+asmlinkage long sys_fsmount(int fs_fd, unsigned int flags, unsigned int ms_flags);
/*
* Architecture-specific system calls
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index f8818e6cddd6..30a2fb85c4b7 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -349,4 +349,6 @@ typedef int __bitwise __kernel_rwf_t;
*/
#define FSOPEN_CLOEXEC 0x00000001
+#define FSMOUNT_CLOEXEC 0x00000001
+
#endif /* _UAPI_LINUX_FS_H */
^ permalink raw reply related
* [PATCH 24/32] vfs: syscall: Add fsopen() to prepare for superblock creation [ver #9]
From: David Howells @ 2018-07-10 22:44 UTC (permalink / raw)
To: viro; +Cc: dhowells, linux-api, linux-fsdevel, torvalds, linux-kernel
In-Reply-To: <153126248868.14533.9751473662727327569.stgit@warthog.procyon.org.uk>
Provide an fsopen() system call that starts the process of preparing to
create a superblock that will then be mountable, using an fd as a context
handle. fsopen() is given the name of the filesystem that will be used:
int mfd = fsopen(const char *fsname, unsigned int flags);
where flags can be 0 or FSOPEN_CLOEXEC.
For example:
sfd = fsopen("ext4", FSOPEN_CLOEXEC);
write(sfd, "s /dev/sdb1"); // note I'm ignoring write's length arg
write(sfd, "o noatime");
write(sfd, "o acl");
write(sfd, "o user_attr");
write(sfd, "o iversion");
write(sfd, "o ");
write(sfd, "r /my/container"); // root inside the fs
write(sfd, "x create"); // create the superblock
fsinfo(sfd, NULL, ...); // query new superblock attributes
mfd = fsmount(sfd, FSMOUNT_CLOEXEC, MS_RELATIME);
move_mount(mfd, "", sfd, AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH);
sfd = fsopen("afs", -1);
write(sfd, "s %grand.central.org:root.cell");
write(sfd, "o cell=grand.central.org");
write(sfd, "r /");
write(sfd, "x create");
mfd = fsmount(sfd, 0, MS_NODEV);
move_mount(mfd, "", sfd, AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH);
If an error is reported at any step, an error message may be available to be
read() back (ENODATA will be reported if there isn't an error available) in
the form:
"e <subsys>:<problem>"
"e SELinux:Mount on mountpoint not permitted"
Once fsmount() has been called, further write() calls will incur EBUSY,
even if the fsmount() fails. read() is still possible to retrieve error
information.
The fsopen() syscall creates a mount context and hangs it of the fd that it
returns.
Netlink is not used because it is optional and would make the core VFS
dependent on the networking layer and also potentially add network
namespace issues.
Note that, for the moment, the caller must have SYS_CAP_ADMIN to use
fsopen().
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-api@vger.kernel.org
---
arch/x86/entry/syscalls/syscall_32.tbl | 1
arch/x86/entry/syscalls/syscall_64.tbl | 1
fs/Makefile | 2
fs/fs_context.c | 4 +
fs/fsopen.c | 209 ++++++++++++++++++++++++++++++++
include/linux/fs_context.h | 2
include/linux/syscalls.h | 1
include/uapi/linux/fs.h | 5 +
8 files changed, 224 insertions(+), 1 deletion(-)
create mode 100644 fs/fsopen.c
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 76d092b7d1b0..1647fefd2969 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -400,3 +400,4 @@
386 i386 rseq sys_rseq __ia32_sys_rseq
387 i386 open_tree sys_open_tree __ia32_sys_open_tree
388 i386 move_mount sys_move_mount __ia32_sys_move_mount
+389 i386 fsopen sys_fsopen __ia32_sys_fsopen
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 37ba4e65eee6..235d33dbccb2 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -345,6 +345,7 @@
334 common rseq __x64_sys_rseq
335 common open_tree __x64_sys_open_tree
336 common move_mount __x64_sys_move_mount
+337 common fsopen __x64_sys_fsopen
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/Makefile b/fs/Makefile
index 7e9ca59ac3a7..d3b33798998e 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -13,7 +13,7 @@ obj-y := open.o read_write.o file_table.o super.o \
seq_file.o xattr.o libfs.o fs-writeback.o \
pnode.o splice.o sync.o utimes.o d_path.o \
stack.o fs_struct.o statfs.o fs_pin.o nsfs.o \
- fs_context.o
+ fs_context.o fsopen.o
ifeq ($(CONFIG_BLOCK),y)
obj-y += buffer.o block_dev.o direct-io.o mpage.o
diff --git a/fs/fs_context.c b/fs/fs_context.c
index b7c84e0aa2f9..a2d745e6d356 100644
--- a/fs/fs_context.c
+++ b/fs/fs_context.c
@@ -251,6 +251,8 @@ struct fs_context *vfs_new_fs_context(struct file_system_type *fs_type,
fc->fs_type = get_filesystem(fs_type);
fc->cred = get_current_cred();
+ mutex_init(&fc->uapi_mutex);
+
switch (purpose) {
case FS_CONTEXT_FOR_KERNEL_MOUNT:
fc->sb_flags |= SB_KERNMOUNT;
@@ -335,6 +337,8 @@ struct fs_context *vfs_dup_fs_context(struct fs_context *src_fc)
if (!fc)
return ERR_PTR(-ENOMEM);
+ mutex_init(&fc->uapi_mutex);
+
fc->fs_private = NULL;
fc->s_fs_info = NULL;
fc->source = NULL;
diff --git a/fs/fsopen.c b/fs/fsopen.c
new file mode 100644
index 000000000000..28bb72bda163
--- /dev/null
+++ b/fs/fsopen.c
@@ -0,0 +1,209 @@
+/* Filesystem access-by-fd.
+ *
+ * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/fs_context.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/security.h>
+#include <linux/anon_inodes.h>
+#include "mount.h"
+
+/*
+ * Userspace writes configuration data and commands to the fd and we parse it
+ * here. For the moment, we assume a single option or command per write. Each
+ * line written is of the form
+ *
+ * <command_type><space><stuff...>
+ *
+ * s /dev/sda1 -- Source device
+ * o noatime -- Option without value
+ * o cell=grand.central.org -- Option with value
+ * x create -- Create a superblock
+ * x reconfigure -- Reconfigure a superblock
+ */
+static ssize_t fscontext_write(struct file *file,
+ const char __user *_buf, size_t len, loff_t *pos)
+{
+ struct fs_context *fc = file->private_data;
+ char opt[2], *data;
+ ssize_t ret;
+
+ if (len < 3 || len > 4095)
+ return -EINVAL;
+
+ if (copy_from_user(opt, _buf, 2) != 0)
+ return -EFAULT;
+ switch (opt[0]) {
+ case 's':
+ case 'o':
+ case 'x':
+ break;
+ default:
+ return -EINVAL;
+ }
+ if (opt[1] != ' ')
+ return -EINVAL;
+
+ data = memdup_user_nul(_buf + 2, len - 2);
+ if (IS_ERR(data))
+ return PTR_ERR(data);
+
+ /* From this point onwards we need to lock the fd against someone
+ * trying to mount it.
+ */
+ ret = mutex_lock_interruptible(&fc->uapi_mutex);
+ if (ret < 0)
+ goto err_free;
+
+ if (fc->phase == FS_CONTEXT_AWAITING_RECONF) {
+ if (fc->fs_type->init_fs_context) {
+ ret = fc->fs_type->init_fs_context(fc, fc->root);
+ if (ret < 0) {
+ fc->phase = FS_CONTEXT_FAILED;
+ goto err_unlock;
+ }
+ } else {
+ /* Leave legacy context ops in place */
+ }
+
+ /* Do the security check last because ->init_fs_context may
+ * change the namespace subscriptions.
+ */
+ ret = security_fs_context_alloc(fc, fc->root);
+ if (ret < 0) {
+ fc->phase = FS_CONTEXT_FAILED;
+ goto err_unlock;
+ }
+
+ fc->phase = FS_CONTEXT_RECONF_PARAMS;
+ }
+
+ ret = -EINVAL;
+ switch (opt[0]) {
+ case 's':
+ if (fc->phase != FS_CONTEXT_CREATE_PARAMS &&
+ fc->phase != FS_CONTEXT_RECONF_PARAMS)
+ goto wrong_phase;
+ ret = vfs_set_fs_source(fc, data, len - 2);
+ if (ret < 0)
+ goto err_unlock;
+ break;
+
+ case 'o':
+ if (fc->phase != FS_CONTEXT_CREATE_PARAMS &&
+ fc->phase != FS_CONTEXT_RECONF_PARAMS)
+ goto wrong_phase;
+ ret = vfs_parse_fs_option(fc, data, len - 2);
+ if (ret < 0)
+ goto err_unlock;
+ break;
+
+ case 'x':
+ if (strcmp(data, "create") == 0) {
+ if (fc->phase != FS_CONTEXT_CREATE_PARAMS)
+ goto wrong_phase;
+ fc->phase = FS_CONTEXT_CREATING;
+ ret = vfs_get_tree(fc);
+ if (ret == 0)
+ fc->phase = FS_CONTEXT_AWAITING_MOUNT;
+ else
+ fc->phase = FS_CONTEXT_FAILED;
+ } else {
+ ret = -EOPNOTSUPP;
+ }
+ if (ret < 0)
+ goto err_unlock;
+ break;
+
+ default:
+ goto err_unlock;
+ }
+
+ ret = len;
+err_unlock:
+ mutex_unlock(&fc->uapi_mutex);
+err_free:
+ kfree(data);
+ return ret;
+
+wrong_phase:
+ ret = -EBUSY;
+ goto err_unlock;
+}
+
+static int fscontext_release(struct inode *inode, struct file *file)
+{
+ struct fs_context *fc = file->private_data;
+
+ if (fc) {
+ file->private_data = NULL;
+ put_fs_context(fc);
+ }
+ return 0;
+}
+
+const struct file_operations fscontext_fs_fops = {
+ .write = fscontext_write,
+ .release = fscontext_release,
+ .llseek = no_llseek,
+};
+
+/*
+ * Attach a filesystem context to a file and an fd.
+ */
+static int fscontext_create_fd(struct fs_context *fc, unsigned int o_flags)
+{
+ int fd;
+
+ fd = anon_inode_getfd("fscontext", &fscontext_fs_fops, fc,
+ O_RDWR | o_flags);
+ if (fd < 0)
+ put_fs_context(fc);
+ return fd;
+}
+
+/*
+ * Open a filesystem by name so that it can be configured for mounting.
+ *
+ * We are allowed to specify a container in which the filesystem will be
+ * opened, thereby indicating which namespaces will be used (notably, which
+ * network namespace will be used for network filesystems).
+ */
+SYSCALL_DEFINE2(fsopen, const char __user *, _fs_name, unsigned int, flags)
+{
+ struct file_system_type *fs_type;
+ struct fs_context *fc;
+ const char *fs_name;
+
+ if (!ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (flags & ~FSOPEN_CLOEXEC)
+ return -EINVAL;
+
+ fs_name = strndup_user(_fs_name, PAGE_SIZE);
+ if (IS_ERR(fs_name))
+ return PTR_ERR(fs_name);
+
+ fs_type = get_fs_type(fs_name);
+ kfree(fs_name);
+ if (!fs_type)
+ return -ENODEV;
+
+ fc = vfs_new_fs_context(fs_type, NULL, 0, FS_CONTEXT_FOR_USER_MOUNT);
+ put_filesystem(fs_type);
+ if (IS_ERR(fc))
+ return PTR_ERR(fc);
+
+ fc->phase = FS_CONTEXT_CREATE_PARAMS;
+ return fscontext_create_fd(fc, flags & FSOPEN_CLOEXEC ? O_CLOEXEC : 0);
+}
diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h
index f157ff935a1e..387f25d7acc4 100644
--- a/include/linux/fs_context.h
+++ b/include/linux/fs_context.h
@@ -14,6 +14,7 @@
#include <linux/kernel.h>
#include <linux/errno.h>
+#include <linux/mutex.h>
struct cred;
struct dentry;
@@ -58,6 +59,7 @@ enum fs_context_phase {
*/
struct fs_context {
const struct fs_context_operations *ops;
+ struct mutex uapi_mutex; /* Userspace access mutex */
struct file_system_type *fs_type;
void *fs_private; /* The filesystem's context */
struct dentry *root; /* The root and superblock */
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 3c0855d9b105..ad6c7ff33c01 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -904,6 +904,7 @@ asmlinkage long sys_open_tree(int dfd, const char __user *path, unsigned flags);
asmlinkage long sys_move_mount(int from_dfd, const char __user *from_path,
int to_dfd, const char __user *to_path,
unsigned int ms_flags);
+asmlinkage long sys_fsopen(const char __user *fs_name, unsigned int flags);
/*
* Architecture-specific system calls
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 1c982eb44ff4..f8818e6cddd6 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -344,4 +344,9 @@ typedef int __bitwise __kernel_rwf_t;
#define RWF_SUPPORTED (RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT |\
RWF_APPEND)
+/*
+ * Flags for fsopen() and co.
+ */
+#define FSOPEN_CLOEXEC 0x00000001
+
#endif /* _UAPI_LINUX_FS_H */
^ permalink raw reply related
* [PATCH 02/32] vfs: syscall: Add move_mount(2) to move mounts around [ver #9]
From: David Howells @ 2018-07-10 22:41 UTC (permalink / raw)
To: viro; +Cc: dhowells, linux-api, linux-fsdevel, torvalds, linux-kernel
In-Reply-To: <153126248868.14533.9751473662727327569.stgit@warthog.procyon.org.uk>
Add a move_mount() system call that will move a mount from one place to
another and, in the next commit, allow to attach an unattached mount tree.
The new system call looks like the following:
int move_mount(int from_dfd, const char *from_path,
int to_dfd, const char *to_path,
unsigned int flags);
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-api@vger.kernel.org
---
arch/x86/entry/syscalls/syscall_32.tbl | 1
arch/x86/entry/syscalls/syscall_64.tbl | 1
fs/namespace.c | 102 ++++++++++++++++++++++++++------
include/linux/lsm_hooks.h | 6 ++
include/linux/security.h | 7 ++
include/linux/syscalls.h | 3 +
include/uapi/linux/mount.h | 11 +++
security/security.c | 5 ++
8 files changed, 118 insertions(+), 18 deletions(-)
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index ea1b413afd47..76d092b7d1b0 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -399,3 +399,4 @@
385 i386 io_pgetevents sys_io_pgetevents __ia32_compat_sys_io_pgetevents
386 i386 rseq sys_rseq __ia32_sys_rseq
387 i386 open_tree sys_open_tree __ia32_sys_open_tree
+388 i386 move_mount sys_move_mount __ia32_sys_move_mount
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 0545bed581dc..37ba4e65eee6 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -344,6 +344,7 @@
333 common io_pgetevents __x64_sys_io_pgetevents
334 common rseq __x64_sys_rseq
335 common open_tree __x64_sys_open_tree
+336 common move_mount __x64_sys_move_mount
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/namespace.c b/fs/namespace.c
index b355a555b4db..e95b2bc8fcfe 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2446,43 +2446,37 @@ static inline int tree_contains_unbindable(struct mount *mnt)
return 0;
}
-static int do_move_mount(struct path *path, const char *old_name)
+static int do_move_mount(struct path *old_path, struct path *new_path)
{
- struct path old_path, parent_path;
+ struct path parent_path = {.mnt = NULL, .dentry = NULL};
struct mount *p;
struct mount *old;
struct mountpoint *mp;
int err;
- if (!old_name || !*old_name)
- return -EINVAL;
- err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
- if (err)
- return err;
- mp = lock_mount(path);
+ mp = lock_mount(new_path);
err = PTR_ERR(mp);
if (IS_ERR(mp))
goto out;
- old = real_mount(old_path.mnt);
- p = real_mount(path->mnt);
+ old = real_mount(old_path->mnt);
+ p = real_mount(new_path->mnt);
err = -EINVAL;
if (!check_mnt(p) || !check_mnt(old))
goto out1;
- if (old->mnt.mnt_flags & MNT_LOCKED)
+ if (!mnt_has_parent(old))
goto out1;
- err = -EINVAL;
- if (old_path.dentry != old_path.mnt->mnt_root)
+ if (old->mnt.mnt_flags & MNT_LOCKED)
goto out1;
- if (!mnt_has_parent(old))
+ if (old_path->dentry != old_path->mnt->mnt_root)
goto out1;
- if (d_is_dir(path->dentry) !=
- d_is_dir(old_path.dentry))
+ if (d_is_dir(new_path->dentry) !=
+ d_is_dir(old_path->dentry))
goto out1;
/*
* Don't move a mount residing in a shared parent.
@@ -2500,7 +2494,8 @@ static int do_move_mount(struct path *path, const char *old_name)
if (p == old)
goto out1;
- err = attach_recursive_mnt(old, real_mount(path->mnt), mp, &parent_path);
+ err = attach_recursive_mnt(old, real_mount(new_path->mnt), mp,
+ &parent_path);
if (err)
goto out1;
@@ -2512,6 +2507,22 @@ static int do_move_mount(struct path *path, const char *old_name)
out:
if (!err)
path_put(&parent_path);
+ return err;
+}
+
+static int do_move_mount_old(struct path *path, const char *old_name)
+{
+ struct path old_path;
+ int err;
+
+ if (!old_name || !*old_name)
+ return -EINVAL;
+
+ err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
+ if (err)
+ return err;
+
+ err = do_move_mount(&old_path, path);
path_put(&old_path);
return err;
}
@@ -2931,7 +2942,7 @@ long do_mount(const char *dev_name, const char __user *dir_name,
else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
retval = do_change_type(&path, flags);
else if (flags & MS_MOVE)
- retval = do_move_mount(&path, dev_name);
+ retval = do_move_mount_old(&path, dev_name);
else
retval = do_new_mount(&path, type_page, sb_flags, mnt_flags,
dev_name, data_page);
@@ -3166,6 +3177,61 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
return ksys_mount(dev_name, dir_name, type, flags, data);
}
+/*
+ * Move a mount from one place to another.
+ *
+ * Note the flags value is a combination of MOVE_MOUNT_* flags.
+ */
+SYSCALL_DEFINE5(move_mount,
+ int, from_dfd, const char *, from_pathname,
+ int, to_dfd, const char *, to_pathname,
+ unsigned int, flags)
+{
+ struct path from_path, to_path;
+ unsigned int lflags;
+ int ret = 0;
+
+ if (!may_mount())
+ return -EPERM;
+
+ if (flags & ~MOVE_MOUNT__MASK)
+ return -EINVAL;
+
+ /* If someone gives a pathname, they aren't permitted to move
+ * from an fd that requires unmount as we can't get at the flag
+ * to clear it afterwards.
+ */
+ lflags = 0;
+ if (flags & MOVE_MOUNT_F_SYMLINKS) lflags |= LOOKUP_FOLLOW;
+ if (flags & MOVE_MOUNT_F_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT;
+ if (flags & MOVE_MOUNT_F_EMPTY_PATH) lflags |= LOOKUP_EMPTY;
+
+ ret = user_path_at(from_dfd, from_pathname, lflags, &from_path);
+ if (ret < 0)
+ return ret;
+
+ lflags = 0;
+ if (flags & MOVE_MOUNT_T_SYMLINKS) lflags |= LOOKUP_FOLLOW;
+ if (flags & MOVE_MOUNT_T_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT;
+ if (flags & MOVE_MOUNT_T_EMPTY_PATH) lflags |= LOOKUP_EMPTY;
+
+ ret = user_path_at(to_dfd, to_pathname, lflags, &to_path);
+ if (ret < 0)
+ goto out_from;
+
+ ret = security_move_mount(&from_path, &to_path);
+ if (ret < 0)
+ goto out_to;
+
+ ret = do_move_mount(&from_path, &to_path);
+
+out_to:
+ path_put(&to_path);
+out_from:
+ path_put(&from_path);
+ return ret;
+}
+
/*
* Return true if path is reachable from root
*
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 8f1131c8dd54..926607defd83 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -144,6 +144,10 @@
* Parse a string of security data filling in the opts structure
* @options string containing all mount options known by the LSM
* @opts binary data structure usable by the LSM
+ * @move_mount:
+ * Check permission before a mount is moved.
+ * @from_path indicates the mount that is going to be moved.
+ * @to_path indicates the mountpoint that will be mounted upon.
* @dentry_init_security:
* Compute a context for a dentry as the inode is not yet available
* since NFSv4 has no label backed by an EA anyway.
@@ -1475,6 +1479,7 @@ union security_list_options {
unsigned long kern_flags,
unsigned long *set_kern_flags);
int (*sb_parse_opts_str)(char *options, struct security_mnt_opts *opts);
+ int (*move_mount)(const struct path *from_path, const struct path *to_path);
int (*dentry_init_security)(struct dentry *dentry, int mode,
const struct qstr *name, void **ctx,
u32 *ctxlen);
@@ -1806,6 +1811,7 @@ struct security_hook_heads {
struct hlist_head sb_set_mnt_opts;
struct hlist_head sb_clone_mnt_opts;
struct hlist_head sb_parse_opts_str;
+ struct hlist_head move_mount;
struct hlist_head dentry_init_security;
struct hlist_head dentry_create_files_as;
#ifdef CONFIG_SECURITY_PATH
diff --git a/include/linux/security.h b/include/linux/security.h
index 63030c85ee19..15d121f156b3 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -245,6 +245,7 @@ int security_sb_clone_mnt_opts(const struct super_block *oldsb,
unsigned long kern_flags,
unsigned long *set_kern_flags);
int security_sb_parse_opts_str(char *options, struct security_mnt_opts *opts);
+int security_move_mount(const struct path *from_path, const struct path *to_path);
int security_dentry_init_security(struct dentry *dentry, int mode,
const struct qstr *name, void **ctx,
u32 *ctxlen);
@@ -598,6 +599,12 @@ static inline int security_sb_parse_opts_str(char *options, struct security_mnt_
return 0;
}
+static inline int security_move_mount(const struct path *from_path,
+ const struct path *to_path)
+{
+ return 0;
+}
+
static inline int security_inode_alloc(struct inode *inode)
{
return 0;
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 3cc6b8f8bd2f..3c0855d9b105 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -901,6 +901,9 @@ asmlinkage long sys_statx(int dfd, const char __user *path, unsigned flags,
asmlinkage long sys_rseq(struct rseq __user *rseq, uint32_t rseq_len,
int flags, uint32_t sig);
asmlinkage long sys_open_tree(int dfd, const char __user *path, unsigned flags);
+asmlinkage long sys_move_mount(int from_dfd, const char __user *from_path,
+ int to_dfd, const char __user *to_path,
+ unsigned int ms_flags);
/*
* Architecture-specific system calls
diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h
index e8db2911adca..89adf0d731ab 100644
--- a/include/uapi/linux/mount.h
+++ b/include/uapi/linux/mount.h
@@ -7,4 +7,15 @@
#define OPEN_TREE_CLONE 1 /* Clone the target tree and attach the clone */
#define OPEN_TREE_CLOEXEC O_CLOEXEC /* Close the file on execve() */
+/*
+ * move_mount() flags.
+ */
+#define MOVE_MOUNT_F_SYMLINKS 0x00000001 /* Follow symlinks on from path */
+#define MOVE_MOUNT_F_AUTOMOUNTS 0x00000002 /* Follow automounts on from path */
+#define MOVE_MOUNT_F_EMPTY_PATH 0x00000004 /* Empty from path permitted */
+#define MOVE_MOUNT_T_SYMLINKS 0x00000010 /* Follow symlinks on to path */
+#define MOVE_MOUNT_T_AUTOMOUNTS 0x00000020 /* Follow automounts on to path */
+#define MOVE_MOUNT_T_EMPTY_PATH 0x00000040 /* Empty to path permitted */
+#define MOVE_MOUNT__MASK 0x00000077
+
#endif /* _UAPI_LINUX_MOUNT_H */
diff --git a/security/security.c b/security/security.c
index 68f46d849abe..c4cbdb7d3a5f 100644
--- a/security/security.c
+++ b/security/security.c
@@ -437,6 +437,11 @@ int security_sb_parse_opts_str(char *options, struct security_mnt_opts *opts)
}
EXPORT_SYMBOL(security_sb_parse_opts_str);
+int security_move_mount(const struct path *from_path, const struct path *to_path)
+{
+ return call_int_hook(move_mount, 0, from_path, to_path);
+}
+
int security_inode_alloc(struct inode *inode)
{
inode->i_security = NULL;
^ permalink raw reply related
* [PATCH 01/32] vfs: syscall: Add open_tree(2) to reference or clone a mount [ver #9]
From: David Howells @ 2018-07-10 22:41 UTC (permalink / raw)
To: viro; +Cc: dhowells, linux-api, linux-fsdevel, torvalds, linux-kernel
In-Reply-To: <153126248868.14533.9751473662727327569.stgit@warthog.procyon.org.uk>
From: Al Viro <viro@zeniv.linux.org.uk>
open_tree(dfd, pathname, flags)
Returns an O_PATH-opened file descriptor or an error.
dfd and pathname specify the location to open, in usual
fashion (see e.g. fstatat(2)). flags should be an OR of
some of the following:
* AT_PATH_EMPTY, AT_NO_AUTOMOUNT, AT_SYMLINK_NOFOLLOW -
same meanings as usual
* OPEN_TREE_CLOEXEC - make the resulting descriptor
close-on-exec
* OPEN_TREE_CLONE or OPEN_TREE_CLONE | AT_RECURSIVE -
instead of opening the location in question, create a detached
mount tree matching the subtree rooted at location specified by
dfd/pathname. With AT_RECURSIVE the entire subtree is cloned,
without it - only the part within in the mount containing the
location in question. In other words, the same as mount --rbind
or mount --bind would've taken. The detached tree will be
dissolved on the final close of obtained file. Creation of such
detached trees requires the same capabilities as doing mount --bind.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
cc: linux-api@vger.kernel.org
---
arch/x86/entry/syscalls/syscall_32.tbl | 1
arch/x86/entry/syscalls/syscall_64.tbl | 1
fs/file_table.c | 9 +-
fs/internal.h | 1
fs/namespace.c | 132 +++++++++++++++++++++++++++-----
include/linux/fs.h | 3 +
include/linux/syscalls.h | 1
include/uapi/linux/fcntl.h | 2
include/uapi/linux/mount.h | 10 ++
9 files changed, 135 insertions(+), 25 deletions(-)
create mode 100644 include/uapi/linux/mount.h
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 3cf7b533b3d1..ea1b413afd47 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -398,3 +398,4 @@
384 i386 arch_prctl sys_arch_prctl __ia32_compat_sys_arch_prctl
385 i386 io_pgetevents sys_io_pgetevents __ia32_compat_sys_io_pgetevents
386 i386 rseq sys_rseq __ia32_sys_rseq
+387 i386 open_tree sys_open_tree __ia32_sys_open_tree
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index f0b1709a5ffb..0545bed581dc 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -343,6 +343,7 @@
332 common statx __x64_sys_statx
333 common io_pgetevents __x64_sys_io_pgetevents
334 common rseq __x64_sys_rseq
+335 common open_tree __x64_sys_open_tree
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/file_table.c b/fs/file_table.c
index 7ec0b3e5f05d..7480271a0d21 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -189,6 +189,7 @@ static void __fput(struct file *file)
struct dentry *dentry = file->f_path.dentry;
struct vfsmount *mnt = file->f_path.mnt;
struct inode *inode = file->f_inode;
+ fmode_t mode = file->f_mode;
might_sleep();
@@ -209,14 +210,14 @@ static void __fput(struct file *file)
file->f_op->release(inode, file);
security_file_free(file);
if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
- !(file->f_mode & FMODE_PATH))) {
+ !(mode & FMODE_PATH))) {
cdev_put(inode->i_cdev);
}
fops_put(file->f_op);
put_pid(file->f_owner.pid);
- if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+ if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
i_readcount_dec(inode);
- if (file->f_mode & FMODE_WRITER) {
+ if (mode & FMODE_WRITER) {
put_write_access(inode);
__mnt_drop_write(mnt);
}
@@ -224,6 +225,8 @@ static void __fput(struct file *file)
file->f_path.mnt = NULL;
file->f_inode = NULL;
file_free(file);
+ if (unlikely(mode & FMODE_NEED_UNMOUNT))
+ dissolve_on_fput(mnt);
dput(dentry);
mntput(mnt);
}
diff --git a/fs/internal.h b/fs/internal.h
index 980d005b21b4..b55575b9b55c 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -85,6 +85,7 @@ extern void __mnt_drop_write(struct vfsmount *);
extern void __mnt_drop_write_file(struct file *);
extern void mnt_drop_write_file_path(struct file *);
+extern void dissolve_on_fput(struct vfsmount *);
/*
* fs_struct.c
*/
diff --git a/fs/namespace.c b/fs/namespace.c
index 8ddd14806799..b355a555b4db 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -20,12 +20,14 @@
#include <linux/init.h> /* init_rootfs */
#include <linux/fs_struct.h> /* get_fs_root et.al. */
#include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */
+#include <linux/file.h>
#include <linux/uaccess.h>
#include <linux/proc_ns.h>
#include <linux/magic.h>
#include <linux/bootmem.h>
#include <linux/task_work.h>
#include <linux/sched/task.h>
+#include <uapi/linux/mount.h>
#include "pnode.h"
#include "internal.h"
@@ -1839,6 +1841,16 @@ struct vfsmount *collect_mounts(const struct path *path)
return &tree->mnt;
}
+void dissolve_on_fput(struct vfsmount *mnt)
+{
+ namespace_lock();
+ lock_mount_hash();
+ mntget(mnt);
+ umount_tree(real_mount(mnt), UMOUNT_SYNC);
+ unlock_mount_hash();
+ namespace_unlock();
+}
+
void drop_collected_mounts(struct vfsmount *mnt)
{
namespace_lock();
@@ -2198,6 +2210,30 @@ static bool has_locked_children(struct mount *mnt, struct dentry *dentry)
return false;
}
+static struct mount *__do_loopback(struct path *old_path, int recurse)
+{
+ struct mount *mnt = ERR_PTR(-EINVAL), *old = real_mount(old_path->mnt);
+
+ if (IS_MNT_UNBINDABLE(old))
+ return mnt;
+
+ if (!check_mnt(old) && old_path->dentry->d_op != &ns_dentry_operations)
+ return mnt;
+
+ if (!recurse && has_locked_children(old, old_path->dentry))
+ return mnt;
+
+ if (recurse)
+ mnt = copy_tree(old, old_path->dentry, CL_COPY_MNT_NS_FILE);
+ else
+ mnt = clone_mnt(old, old_path->dentry, 0);
+
+ if (!IS_ERR(mnt))
+ mnt->mnt.mnt_flags &= ~MNT_LOCKED;
+
+ return mnt;
+}
+
/*
* do loopback mount.
*/
@@ -2205,7 +2241,7 @@ static int do_loopback(struct path *path, const char *old_name,
int recurse)
{
struct path old_path;
- struct mount *mnt = NULL, *old, *parent;
+ struct mount *mnt = NULL, *parent;
struct mountpoint *mp;
int err;
if (!old_name || !*old_name)
@@ -2219,38 +2255,21 @@ static int do_loopback(struct path *path, const char *old_name,
goto out;
mp = lock_mount(path);
- err = PTR_ERR(mp);
- if (IS_ERR(mp))
+ if (IS_ERR(mp)) {
+ err = PTR_ERR(mp);
goto out;
+ }
- old = real_mount(old_path.mnt);
parent = real_mount(path->mnt);
-
- err = -EINVAL;
- if (IS_MNT_UNBINDABLE(old))
- goto out2;
-
if (!check_mnt(parent))
goto out2;
- if (!check_mnt(old) && old_path.dentry->d_op != &ns_dentry_operations)
- goto out2;
-
- if (!recurse && has_locked_children(old, old_path.dentry))
- goto out2;
-
- if (recurse)
- mnt = copy_tree(old, old_path.dentry, CL_COPY_MNT_NS_FILE);
- else
- mnt = clone_mnt(old, old_path.dentry, 0);
-
+ mnt = __do_loopback(&old_path, recurse);
if (IS_ERR(mnt)) {
err = PTR_ERR(mnt);
goto out2;
}
- mnt->mnt.mnt_flags &= ~MNT_LOCKED;
-
err = graft_tree(mnt, parent, mp);
if (err) {
lock_mount_hash();
@@ -2264,6 +2283,75 @@ static int do_loopback(struct path *path, const char *old_name,
return err;
}
+SYSCALL_DEFINE3(open_tree, int, dfd, const char *, filename, unsigned, flags)
+{
+ struct file *file;
+ struct path path;
+ int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW;
+ bool detached = flags & OPEN_TREE_CLONE;
+ int error;
+ int fd;
+
+ BUILD_BUG_ON(OPEN_TREE_CLOEXEC != O_CLOEXEC);
+
+ if (flags & ~(AT_EMPTY_PATH | AT_NO_AUTOMOUNT | AT_RECURSIVE |
+ AT_SYMLINK_NOFOLLOW | OPEN_TREE_CLONE |
+ OPEN_TREE_CLOEXEC))
+ return -EINVAL;
+
+ if ((flags & (AT_RECURSIVE | OPEN_TREE_CLONE)) == AT_RECURSIVE)
+ return -EINVAL;
+
+ if (flags & AT_NO_AUTOMOUNT)
+ lookup_flags &= ~LOOKUP_AUTOMOUNT;
+ if (flags & AT_SYMLINK_NOFOLLOW)
+ lookup_flags &= ~LOOKUP_FOLLOW;
+ if (flags & AT_EMPTY_PATH)
+ lookup_flags |= LOOKUP_EMPTY;
+
+ if (detached && !may_mount())
+ return -EPERM;
+
+ fd = get_unused_fd_flags(flags & O_CLOEXEC);
+ if (fd < 0)
+ return fd;
+
+ error = user_path_at(dfd, filename, lookup_flags, &path);
+ if (error)
+ goto out;
+
+ if (detached) {
+ struct mount *mnt = __do_loopback(&path, flags & AT_RECURSIVE);
+ if (IS_ERR(mnt)) {
+ error = PTR_ERR(mnt);
+ goto out2;
+ }
+ mntput(path.mnt);
+ path.mnt = &mnt->mnt;
+ }
+
+ file = dentry_open(&path, O_PATH, current_cred());
+ if (IS_ERR(file)) {
+ error = PTR_ERR(file);
+ goto out3;
+ }
+
+ if (detached)
+ file->f_mode |= FMODE_NEED_UNMOUNT;
+ path_put(&path);
+ fd_install(fd, file);
+ return fd;
+
+out3:
+ if (detached)
+ dissolve_on_fput(path.mnt);
+out2:
+ path_put(&path);
+out:
+ put_unused_fd(fd);
+ return error;
+}
+
static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
{
int error = 0;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5c91108846db..00e255c195f2 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -154,6 +154,9 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
/* File is capable of returning -EAGAIN if I/O will block */
#define FMODE_NOWAIT ((__force fmode_t)0x8000000)
+/* File represents mount that needs unmounting */
+#define FMODE_NEED_UNMOUNT ((__force fmode_t)0x10000000)
+
/*
* Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
* that indicates that they should check the contents of the iovec are
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 73810808cdf2..3cc6b8f8bd2f 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -900,6 +900,7 @@ asmlinkage long sys_statx(int dfd, const char __user *path, unsigned flags,
unsigned mask, struct statx __user *buffer);
asmlinkage long sys_rseq(struct rseq __user *rseq, uint32_t rseq_len,
int flags, uint32_t sig);
+asmlinkage long sys_open_tree(int dfd, const char __user *path, unsigned flags);
/*
* Architecture-specific system calls
diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
index 6448cdd9a350..594b85f7cb86 100644
--- a/include/uapi/linux/fcntl.h
+++ b/include/uapi/linux/fcntl.h
@@ -90,5 +90,7 @@
#define AT_STATX_FORCE_SYNC 0x2000 /* - Force the attributes to be sync'd with the server */
#define AT_STATX_DONT_SYNC 0x4000 /* - Don't sync attributes with the server */
+#define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */
+
#endif /* _UAPI_LINUX_FCNTL_H */
diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h
new file mode 100644
index 000000000000..e8db2911adca
--- /dev/null
+++ b/include/uapi/linux/mount.h
@@ -0,0 +1,10 @@
+#ifndef _UAPI_LINUX_MOUNT_H
+#define _UAPI_LINUX_MOUNT_H
+
+/*
+ * open_tree() flags.
+ */
+#define OPEN_TREE_CLONE 1 /* Clone the target tree and attach the clone */
+#define OPEN_TREE_CLOEXEC O_CLOEXEC /* Close the file on execve() */
+
+#endif /* _UAPI_LINUX_MOUNT_H */
^ permalink raw reply related
* [PATCH 02/32] vfs: syscall: Add move_mount(2) to move mounts around
From: David Howells @ 2018-07-10 22:41 UTC (permalink / raw)
To: viro; +Cc: dhowells, linux-api, linux-fsdevel, torvalds, linux-kernel
In-Reply-To: <153126245717.14372.12511335851917797573.stgit@warthog.procyon.org.uk>
Add a move_mount() system call that will move a mount from one place to
another and, in the next commit, allow to attach an unattached mount tree.
The new system call looks like the following:
int move_mount(int from_dfd, const char *from_path,
int to_dfd, const char *to_path,
unsigned int flags);
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-api@vger.kernel.org
---
arch/x86/entry/syscalls/syscall_32.tbl | 1
arch/x86/entry/syscalls/syscall_64.tbl | 1
fs/namespace.c | 102 ++++++++++++++++++++++++++------
include/linux/lsm_hooks.h | 6 ++
include/linux/security.h | 7 ++
include/linux/syscalls.h | 3 +
include/uapi/linux/mount.h | 11 +++
security/security.c | 5 ++
8 files changed, 118 insertions(+), 18 deletions(-)
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index ea1b413afd47..76d092b7d1b0 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -399,3 +399,4 @@
385 i386 io_pgetevents sys_io_pgetevents __ia32_compat_sys_io_pgetevents
386 i386 rseq sys_rseq __ia32_sys_rseq
387 i386 open_tree sys_open_tree __ia32_sys_open_tree
+388 i386 move_mount sys_move_mount __ia32_sys_move_mount
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 0545bed581dc..37ba4e65eee6 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -344,6 +344,7 @@
333 common io_pgetevents __x64_sys_io_pgetevents
334 common rseq __x64_sys_rseq
335 common open_tree __x64_sys_open_tree
+336 common move_mount __x64_sys_move_mount
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/namespace.c b/fs/namespace.c
index b355a555b4db..e95b2bc8fcfe 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2446,43 +2446,37 @@ static inline int tree_contains_unbindable(struct mount *mnt)
return 0;
}
-static int do_move_mount(struct path *path, const char *old_name)
+static int do_move_mount(struct path *old_path, struct path *new_path)
{
- struct path old_path, parent_path;
+ struct path parent_path = {.mnt = NULL, .dentry = NULL};
struct mount *p;
struct mount *old;
struct mountpoint *mp;
int err;
- if (!old_name || !*old_name)
- return -EINVAL;
- err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
- if (err)
- return err;
- mp = lock_mount(path);
+ mp = lock_mount(new_path);
err = PTR_ERR(mp);
if (IS_ERR(mp))
goto out;
- old = real_mount(old_path.mnt);
- p = real_mount(path->mnt);
+ old = real_mount(old_path->mnt);
+ p = real_mount(new_path->mnt);
err = -EINVAL;
if (!check_mnt(p) || !check_mnt(old))
goto out1;
- if (old->mnt.mnt_flags & MNT_LOCKED)
+ if (!mnt_has_parent(old))
goto out1;
- err = -EINVAL;
- if (old_path.dentry != old_path.mnt->mnt_root)
+ if (old->mnt.mnt_flags & MNT_LOCKED)
goto out1;
- if (!mnt_has_parent(old))
+ if (old_path->dentry != old_path->mnt->mnt_root)
goto out1;
- if (d_is_dir(path->dentry) !=
- d_is_dir(old_path.dentry))
+ if (d_is_dir(new_path->dentry) !=
+ d_is_dir(old_path->dentry))
goto out1;
/*
* Don't move a mount residing in a shared parent.
@@ -2500,7 +2494,8 @@ static int do_move_mount(struct path *path, const char *old_name)
if (p == old)
goto out1;
- err = attach_recursive_mnt(old, real_mount(path->mnt), mp, &parent_path);
+ err = attach_recursive_mnt(old, real_mount(new_path->mnt), mp,
+ &parent_path);
if (err)
goto out1;
@@ -2512,6 +2507,22 @@ static int do_move_mount(struct path *path, const char *old_name)
out:
if (!err)
path_put(&parent_path);
+ return err;
+}
+
+static int do_move_mount_old(struct path *path, const char *old_name)
+{
+ struct path old_path;
+ int err;
+
+ if (!old_name || !*old_name)
+ return -EINVAL;
+
+ err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
+ if (err)
+ return err;
+
+ err = do_move_mount(&old_path, path);
path_put(&old_path);
return err;
}
@@ -2931,7 +2942,7 @@ long do_mount(const char *dev_name, const char __user *dir_name,
else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
retval = do_change_type(&path, flags);
else if (flags & MS_MOVE)
- retval = do_move_mount(&path, dev_name);
+ retval = do_move_mount_old(&path, dev_name);
else
retval = do_new_mount(&path, type_page, sb_flags, mnt_flags,
dev_name, data_page);
@@ -3166,6 +3177,61 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
return ksys_mount(dev_name, dir_name, type, flags, data);
}
+/*
+ * Move a mount from one place to another.
+ *
+ * Note the flags value is a combination of MOVE_MOUNT_* flags.
+ */
+SYSCALL_DEFINE5(move_mount,
+ int, from_dfd, const char *, from_pathname,
+ int, to_dfd, const char *, to_pathname,
+ unsigned int, flags)
+{
+ struct path from_path, to_path;
+ unsigned int lflags;
+ int ret = 0;
+
+ if (!may_mount())
+ return -EPERM;
+
+ if (flags & ~MOVE_MOUNT__MASK)
+ return -EINVAL;
+
+ /* If someone gives a pathname, they aren't permitted to move
+ * from an fd that requires unmount as we can't get at the flag
+ * to clear it afterwards.
+ */
+ lflags = 0;
+ if (flags & MOVE_MOUNT_F_SYMLINKS) lflags |= LOOKUP_FOLLOW;
+ if (flags & MOVE_MOUNT_F_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT;
+ if (flags & MOVE_MOUNT_F_EMPTY_PATH) lflags |= LOOKUP_EMPTY;
+
+ ret = user_path_at(from_dfd, from_pathname, lflags, &from_path);
+ if (ret < 0)
+ return ret;
+
+ lflags = 0;
+ if (flags & MOVE_MOUNT_T_SYMLINKS) lflags |= LOOKUP_FOLLOW;
+ if (flags & MOVE_MOUNT_T_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT;
+ if (flags & MOVE_MOUNT_T_EMPTY_PATH) lflags |= LOOKUP_EMPTY;
+
+ ret = user_path_at(to_dfd, to_pathname, lflags, &to_path);
+ if (ret < 0)
+ goto out_from;
+
+ ret = security_move_mount(&from_path, &to_path);
+ if (ret < 0)
+ goto out_to;
+
+ ret = do_move_mount(&from_path, &to_path);
+
+out_to:
+ path_put(&to_path);
+out_from:
+ path_put(&from_path);
+ return ret;
+}
+
/*
* Return true if path is reachable from root
*
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 8f1131c8dd54..926607defd83 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -144,6 +144,10 @@
* Parse a string of security data filling in the opts structure
* @options string containing all mount options known by the LSM
* @opts binary data structure usable by the LSM
+ * @move_mount:
+ * Check permission before a mount is moved.
+ * @from_path indicates the mount that is going to be moved.
+ * @to_path indicates the mountpoint that will be mounted upon.
* @dentry_init_security:
* Compute a context for a dentry as the inode is not yet available
* since NFSv4 has no label backed by an EA anyway.
@@ -1475,6 +1479,7 @@ union security_list_options {
unsigned long kern_flags,
unsigned long *set_kern_flags);
int (*sb_parse_opts_str)(char *options, struct security_mnt_opts *opts);
+ int (*move_mount)(const struct path *from_path, const struct path *to_path);
int (*dentry_init_security)(struct dentry *dentry, int mode,
const struct qstr *name, void **ctx,
u32 *ctxlen);
@@ -1806,6 +1811,7 @@ struct security_hook_heads {
struct hlist_head sb_set_mnt_opts;
struct hlist_head sb_clone_mnt_opts;
struct hlist_head sb_parse_opts_str;
+ struct hlist_head move_mount;
struct hlist_head dentry_init_security;
struct hlist_head dentry_create_files_as;
#ifdef CONFIG_SECURITY_PATH
diff --git a/include/linux/security.h b/include/linux/security.h
index 63030c85ee19..15d121f156b3 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -245,6 +245,7 @@ int security_sb_clone_mnt_opts(const struct super_block *oldsb,
unsigned long kern_flags,
unsigned long *set_kern_flags);
int security_sb_parse_opts_str(char *options, struct security_mnt_opts *opts);
+int security_move_mount(const struct path *from_path, const struct path *to_path);
int security_dentry_init_security(struct dentry *dentry, int mode,
const struct qstr *name, void **ctx,
u32 *ctxlen);
@@ -598,6 +599,12 @@ static inline int security_sb_parse_opts_str(char *options, struct security_mnt_
return 0;
}
+static inline int security_move_mount(const struct path *from_path,
+ const struct path *to_path)
+{
+ return 0;
+}
+
static inline int security_inode_alloc(struct inode *inode)
{
return 0;
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 3cc6b8f8bd2f..3c0855d9b105 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -901,6 +901,9 @@ asmlinkage long sys_statx(int dfd, const char __user *path, unsigned flags,
asmlinkage long sys_rseq(struct rseq __user *rseq, uint32_t rseq_len,
int flags, uint32_t sig);
asmlinkage long sys_open_tree(int dfd, const char __user *path, unsigned flags);
+asmlinkage long sys_move_mount(int from_dfd, const char __user *from_path,
+ int to_dfd, const char __user *to_path,
+ unsigned int ms_flags);
/*
* Architecture-specific system calls
diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h
index e8db2911adca..89adf0d731ab 100644
--- a/include/uapi/linux/mount.h
+++ b/include/uapi/linux/mount.h
@@ -7,4 +7,15 @@
#define OPEN_TREE_CLONE 1 /* Clone the target tree and attach the clone */
#define OPEN_TREE_CLOEXEC O_CLOEXEC /* Close the file on execve() */
+/*
+ * move_mount() flags.
+ */
+#define MOVE_MOUNT_F_SYMLINKS 0x00000001 /* Follow symlinks on from path */
+#define MOVE_MOUNT_F_AUTOMOUNTS 0x00000002 /* Follow automounts on from path */
+#define MOVE_MOUNT_F_EMPTY_PATH 0x00000004 /* Empty from path permitted */
+#define MOVE_MOUNT_T_SYMLINKS 0x00000010 /* Follow symlinks on to path */
+#define MOVE_MOUNT_T_AUTOMOUNTS 0x00000020 /* Follow automounts on to path */
+#define MOVE_MOUNT_T_EMPTY_PATH 0x00000040 /* Empty to path permitted */
+#define MOVE_MOUNT__MASK 0x00000077
+
#endif /* _UAPI_LINUX_MOUNT_H */
diff --git a/security/security.c b/security/security.c
index 68f46d849abe..c4cbdb7d3a5f 100644
--- a/security/security.c
+++ b/security/security.c
@@ -437,6 +437,11 @@ int security_sb_parse_opts_str(char *options, struct security_mnt_opts *opts)
}
EXPORT_SYMBOL(security_sb_parse_opts_str);
+int security_move_mount(const struct path *from_path, const struct path *to_path)
+{
+ return call_int_hook(move_mount, 0, from_path, to_path);
+}
+
int security_inode_alloc(struct inode *inode)
{
inode->i_security = NULL;
^ permalink raw reply related
* [PATCH 01/32] vfs: syscall: Add open_tree(2) to reference or clone a mount
From: David Howells @ 2018-07-10 22:40 UTC (permalink / raw)
To: viro; +Cc: dhowells, linux-api, linux-fsdevel, torvalds, linux-kernel
From: Al Viro <viro@zeniv.linux.org.uk>
open_tree(dfd, pathname, flags)
Returns an O_PATH-opened file descriptor or an error.
dfd and pathname specify the location to open, in usual
fashion (see e.g. fstatat(2)). flags should be an OR of
some of the following:
* AT_PATH_EMPTY, AT_NO_AUTOMOUNT, AT_SYMLINK_NOFOLLOW -
same meanings as usual
* OPEN_TREE_CLOEXEC - make the resulting descriptor
close-on-exec
* OPEN_TREE_CLONE or OPEN_TREE_CLONE | AT_RECURSIVE -
instead of opening the location in question, create a detached
mount tree matching the subtree rooted at location specified by
dfd/pathname. With AT_RECURSIVE the entire subtree is cloned,
without it - only the part within in the mount containing the
location in question. In other words, the same as mount --rbind
or mount --bind would've taken. The detached tree will be
dissolved on the final close of obtained file. Creation of such
detached trees requires the same capabilities as doing mount --bind.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
cc: linux-api@vger.kernel.org
---
arch/x86/entry/syscalls/syscall_32.tbl | 1
arch/x86/entry/syscalls/syscall_64.tbl | 1
fs/file_table.c | 9 +-
fs/internal.h | 1
fs/namespace.c | 132 +++++++++++++++++++++++++++-----
include/linux/fs.h | 3 +
include/linux/syscalls.h | 1
include/uapi/linux/fcntl.h | 2
include/uapi/linux/mount.h | 10 ++
9 files changed, 135 insertions(+), 25 deletions(-)
create mode 100644 include/uapi/linux/mount.h
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 3cf7b533b3d1..ea1b413afd47 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -398,3 +398,4 @@
384 i386 arch_prctl sys_arch_prctl __ia32_compat_sys_arch_prctl
385 i386 io_pgetevents sys_io_pgetevents __ia32_compat_sys_io_pgetevents
386 i386 rseq sys_rseq __ia32_sys_rseq
+387 i386 open_tree sys_open_tree __ia32_sys_open_tree
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index f0b1709a5ffb..0545bed581dc 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -343,6 +343,7 @@
332 common statx __x64_sys_statx
333 common io_pgetevents __x64_sys_io_pgetevents
334 common rseq __x64_sys_rseq
+335 common open_tree __x64_sys_open_tree
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/file_table.c b/fs/file_table.c
index 7ec0b3e5f05d..7480271a0d21 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -189,6 +189,7 @@ static void __fput(struct file *file)
struct dentry *dentry = file->f_path.dentry;
struct vfsmount *mnt = file->f_path.mnt;
struct inode *inode = file->f_inode;
+ fmode_t mode = file->f_mode;
might_sleep();
@@ -209,14 +210,14 @@ static void __fput(struct file *file)
file->f_op->release(inode, file);
security_file_free(file);
if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
- !(file->f_mode & FMODE_PATH))) {
+ !(mode & FMODE_PATH))) {
cdev_put(inode->i_cdev);
}
fops_put(file->f_op);
put_pid(file->f_owner.pid);
- if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+ if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
i_readcount_dec(inode);
- if (file->f_mode & FMODE_WRITER) {
+ if (mode & FMODE_WRITER) {
put_write_access(inode);
__mnt_drop_write(mnt);
}
@@ -224,6 +225,8 @@ static void __fput(struct file *file)
file->f_path.mnt = NULL;
file->f_inode = NULL;
file_free(file);
+ if (unlikely(mode & FMODE_NEED_UNMOUNT))
+ dissolve_on_fput(mnt);
dput(dentry);
mntput(mnt);
}
diff --git a/fs/internal.h b/fs/internal.h
index 980d005b21b4..b55575b9b55c 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -85,6 +85,7 @@ extern void __mnt_drop_write(struct vfsmount *);
extern void __mnt_drop_write_file(struct file *);
extern void mnt_drop_write_file_path(struct file *);
+extern void dissolve_on_fput(struct vfsmount *);
/*
* fs_struct.c
*/
diff --git a/fs/namespace.c b/fs/namespace.c
index 8ddd14806799..b355a555b4db 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -20,12 +20,14 @@
#include <linux/init.h> /* init_rootfs */
#include <linux/fs_struct.h> /* get_fs_root et.al. */
#include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */
+#include <linux/file.h>
#include <linux/uaccess.h>
#include <linux/proc_ns.h>
#include <linux/magic.h>
#include <linux/bootmem.h>
#include <linux/task_work.h>
#include <linux/sched/task.h>
+#include <uapi/linux/mount.h>
#include "pnode.h"
#include "internal.h"
@@ -1839,6 +1841,16 @@ struct vfsmount *collect_mounts(const struct path *path)
return &tree->mnt;
}
+void dissolve_on_fput(struct vfsmount *mnt)
+{
+ namespace_lock();
+ lock_mount_hash();
+ mntget(mnt);
+ umount_tree(real_mount(mnt), UMOUNT_SYNC);
+ unlock_mount_hash();
+ namespace_unlock();
+}
+
void drop_collected_mounts(struct vfsmount *mnt)
{
namespace_lock();
@@ -2198,6 +2210,30 @@ static bool has_locked_children(struct mount *mnt, struct dentry *dentry)
return false;
}
+static struct mount *__do_loopback(struct path *old_path, int recurse)
+{
+ struct mount *mnt = ERR_PTR(-EINVAL), *old = real_mount(old_path->mnt);
+
+ if (IS_MNT_UNBINDABLE(old))
+ return mnt;
+
+ if (!check_mnt(old) && old_path->dentry->d_op != &ns_dentry_operations)
+ return mnt;
+
+ if (!recurse && has_locked_children(old, old_path->dentry))
+ return mnt;
+
+ if (recurse)
+ mnt = copy_tree(old, old_path->dentry, CL_COPY_MNT_NS_FILE);
+ else
+ mnt = clone_mnt(old, old_path->dentry, 0);
+
+ if (!IS_ERR(mnt))
+ mnt->mnt.mnt_flags &= ~MNT_LOCKED;
+
+ return mnt;
+}
+
/*
* do loopback mount.
*/
@@ -2205,7 +2241,7 @@ static int do_loopback(struct path *path, const char *old_name,
int recurse)
{
struct path old_path;
- struct mount *mnt = NULL, *old, *parent;
+ struct mount *mnt = NULL, *parent;
struct mountpoint *mp;
int err;
if (!old_name || !*old_name)
@@ -2219,38 +2255,21 @@ static int do_loopback(struct path *path, const char *old_name,
goto out;
mp = lock_mount(path);
- err = PTR_ERR(mp);
- if (IS_ERR(mp))
+ if (IS_ERR(mp)) {
+ err = PTR_ERR(mp);
goto out;
+ }
- old = real_mount(old_path.mnt);
parent = real_mount(path->mnt);
-
- err = -EINVAL;
- if (IS_MNT_UNBINDABLE(old))
- goto out2;
-
if (!check_mnt(parent))
goto out2;
- if (!check_mnt(old) && old_path.dentry->d_op != &ns_dentry_operations)
- goto out2;
-
- if (!recurse && has_locked_children(old, old_path.dentry))
- goto out2;
-
- if (recurse)
- mnt = copy_tree(old, old_path.dentry, CL_COPY_MNT_NS_FILE);
- else
- mnt = clone_mnt(old, old_path.dentry, 0);
-
+ mnt = __do_loopback(&old_path, recurse);
if (IS_ERR(mnt)) {
err = PTR_ERR(mnt);
goto out2;
}
- mnt->mnt.mnt_flags &= ~MNT_LOCKED;
-
err = graft_tree(mnt, parent, mp);
if (err) {
lock_mount_hash();
@@ -2264,6 +2283,75 @@ static int do_loopback(struct path *path, const char *old_name,
return err;
}
+SYSCALL_DEFINE3(open_tree, int, dfd, const char *, filename, unsigned, flags)
+{
+ struct file *file;
+ struct path path;
+ int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW;
+ bool detached = flags & OPEN_TREE_CLONE;
+ int error;
+ int fd;
+
+ BUILD_BUG_ON(OPEN_TREE_CLOEXEC != O_CLOEXEC);
+
+ if (flags & ~(AT_EMPTY_PATH | AT_NO_AUTOMOUNT | AT_RECURSIVE |
+ AT_SYMLINK_NOFOLLOW | OPEN_TREE_CLONE |
+ OPEN_TREE_CLOEXEC))
+ return -EINVAL;
+
+ if ((flags & (AT_RECURSIVE | OPEN_TREE_CLONE)) == AT_RECURSIVE)
+ return -EINVAL;
+
+ if (flags & AT_NO_AUTOMOUNT)
+ lookup_flags &= ~LOOKUP_AUTOMOUNT;
+ if (flags & AT_SYMLINK_NOFOLLOW)
+ lookup_flags &= ~LOOKUP_FOLLOW;
+ if (flags & AT_EMPTY_PATH)
+ lookup_flags |= LOOKUP_EMPTY;
+
+ if (detached && !may_mount())
+ return -EPERM;
+
+ fd = get_unused_fd_flags(flags & O_CLOEXEC);
+ if (fd < 0)
+ return fd;
+
+ error = user_path_at(dfd, filename, lookup_flags, &path);
+ if (error)
+ goto out;
+
+ if (detached) {
+ struct mount *mnt = __do_loopback(&path, flags & AT_RECURSIVE);
+ if (IS_ERR(mnt)) {
+ error = PTR_ERR(mnt);
+ goto out2;
+ }
+ mntput(path.mnt);
+ path.mnt = &mnt->mnt;
+ }
+
+ file = dentry_open(&path, O_PATH, current_cred());
+ if (IS_ERR(file)) {
+ error = PTR_ERR(file);
+ goto out3;
+ }
+
+ if (detached)
+ file->f_mode |= FMODE_NEED_UNMOUNT;
+ path_put(&path);
+ fd_install(fd, file);
+ return fd;
+
+out3:
+ if (detached)
+ dissolve_on_fput(path.mnt);
+out2:
+ path_put(&path);
+out:
+ put_unused_fd(fd);
+ return error;
+}
+
static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
{
int error = 0;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5c91108846db..00e255c195f2 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -154,6 +154,9 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
/* File is capable of returning -EAGAIN if I/O will block */
#define FMODE_NOWAIT ((__force fmode_t)0x8000000)
+/* File represents mount that needs unmounting */
+#define FMODE_NEED_UNMOUNT ((__force fmode_t)0x10000000)
+
/*
* Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
* that indicates that they should check the contents of the iovec are
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 73810808cdf2..3cc6b8f8bd2f 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -900,6 +900,7 @@ asmlinkage long sys_statx(int dfd, const char __user *path, unsigned flags,
unsigned mask, struct statx __user *buffer);
asmlinkage long sys_rseq(struct rseq __user *rseq, uint32_t rseq_len,
int flags, uint32_t sig);
+asmlinkage long sys_open_tree(int dfd, const char __user *path, unsigned flags);
/*
* Architecture-specific system calls
diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
index 6448cdd9a350..594b85f7cb86 100644
--- a/include/uapi/linux/fcntl.h
+++ b/include/uapi/linux/fcntl.h
@@ -90,5 +90,7 @@
#define AT_STATX_FORCE_SYNC 0x2000 /* - Force the attributes to be sync'd with the server */
#define AT_STATX_DONT_SYNC 0x4000 /* - Don't sync attributes with the server */
+#define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */
+
#endif /* _UAPI_LINUX_FCNTL_H */
diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h
new file mode 100644
index 000000000000..e8db2911adca
--- /dev/null
+++ b/include/uapi/linux/mount.h
@@ -0,0 +1,10 @@
+#ifndef _UAPI_LINUX_MOUNT_H
+#define _UAPI_LINUX_MOUNT_H
+
+/*
+ * open_tree() flags.
+ */
+#define OPEN_TREE_CLONE 1 /* Clone the target tree and attach the clone */
+#define OPEN_TREE_CLOEXEC O_CLOEXEC /* Close the file on execve() */
+
+#endif /* _UAPI_LINUX_MOUNT_H */
^ permalink raw reply related
* [RFC PATCH v2 27/27] x86/cet: Add arch_prctl functions for CET
From: Yu-cheng Yu @ 2018-07-10 22:26 UTC (permalink / raw)
To: x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar, linux-kernel,
linux-doc, linux-mm, linux-arch, linux-api, Arnd Bergmann,
Andy Lutomirski, Balbir Singh, Cyrill Gorcunov, Dave Hansen,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek
Cc: Yu-cheng Yu
In-Reply-To: <20180710222639.8241-1-yu-cheng.yu@intel.com>
arch_prctl(ARCH_CET_STATUS, unsigned long *addr)
Return CET feature status.
The parameter 'addr' is a pointer to a user buffer.
On returning to the caller, the kernel fills the following
information:
*addr = SHSTK/IBT status
*(addr + 1) = SHSTK base address
*(addr + 2) = SHSTK size
arch_prctl(ARCH_CET_DISABLE, unsigned long features)
Disable SHSTK and/or IBT specified in 'features'. Return -EPERM
if CET is locked out.
arch_prctl(ARCH_CET_LOCK)
Lock out CET feature.
arch_prctl(ARCH_CET_ALLOC_SHSTK, unsigned long *addr)
Allocate a new SHSTK.
The parameter 'addr' is a pointer to a user buffer and indicates
the desired SHSTK size to allocate. On returning to the caller
the buffer contains the address of the new SHSTK.
arch_prctl(ARCH_CET_LEGACY_BITMAP, unsigned long *addr)
Allocate an IBT legacy code bitmap if the current task does not
have one.
The parameter 'addr' is a pointer to a user buffer.
On returning to the caller, the kernel fills the following
information:
*addr = IBT bitmap base address
*(addr + 1) = IBT bitmap size
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/include/asm/cet.h | 5 ++
arch/x86/include/uapi/asm/prctl.h | 6 ++
arch/x86/kernel/Makefile | 2 +-
arch/x86/kernel/cet.c | 26 ++++++
arch/x86/kernel/cet_prctl.c | 141 ++++++++++++++++++++++++++++++
arch/x86/kernel/elf.c | 4 +
arch/x86/kernel/process.c | 6 ++
7 files changed, 189 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/kernel/cet_prctl.c
diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h
index d5737f3346f2..50b5284c6667 100644
--- a/arch/x86/include/asm/cet.h
+++ b/arch/x86/include/asm/cet.h
@@ -16,11 +16,14 @@ struct cet_status {
unsigned long ibt_bitmap_size;
unsigned int shstk_enabled:1;
unsigned int ibt_enabled:1;
+ unsigned int locked:1;
};
#ifdef CONFIG_X86_INTEL_CET
+int prctl_cet(int option, unsigned long arg2);
int cet_setup_shstk(void);
int cet_setup_thread_shstk(struct task_struct *p);
+int cet_alloc_shstk(unsigned long *arg);
void cet_disable_shstk(void);
void cet_disable_free_shstk(struct task_struct *p);
int cet_restore_signal(unsigned long ssp);
@@ -29,8 +32,10 @@ int cet_setup_ibt(void);
int cet_setup_ibt_bitmap(void);
void cet_disable_ibt(void);
#else
+static inline int prctl_cet(int option, unsigned long arg2) { return 0; }
static inline int cet_setup_shstk(void) { return 0; }
static inline int cet_setup_thread_shstk(struct task_struct *p) { return 0; }
+static inline int cet_alloc_shstk(unsigned long *arg) { return -EINVAL; }
static inline void cet_disable_shstk(void) {}
static inline void cet_disable_free_shstk(struct task_struct *p) {}
static inline int cet_restore_signal(unsigned long ssp) { return 0; }
diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h
index 5a6aac9fa41f..52ec04e443c5 100644
--- a/arch/x86/include/uapi/asm/prctl.h
+++ b/arch/x86/include/uapi/asm/prctl.h
@@ -14,4 +14,10 @@
#define ARCH_MAP_VDSO_32 0x2002
#define ARCH_MAP_VDSO_64 0x2003
+#define ARCH_CET_STATUS 0x3001
+#define ARCH_CET_DISABLE 0x3002
+#define ARCH_CET_LOCK 0x3003
+#define ARCH_CET_LEGACY_BITMAP 0x3004
+#define ARCH_CET_ALLOC_SHSTK 0x3005
+
#endif /* _ASM_X86_PRCTL_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 36b14ef410c8..b9e6cdc6b4f7 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -139,7 +139,7 @@ obj-$(CONFIG_UNWINDER_ORC) += unwind_orc.o
obj-$(CONFIG_UNWINDER_FRAME_POINTER) += unwind_frame.o
obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
-obj-$(CONFIG_X86_INTEL_CET) += cet.o
+obj-$(CONFIG_X86_INTEL_CET) += cet.o cet_prctl.o
obj-$(CONFIG_ARCH_HAS_PROGRAM_PROPERTIES) += elf.o
diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c
index 2a366a5ccf20..20ce9ac8a0df 100644
--- a/arch/x86/kernel/cet.c
+++ b/arch/x86/kernel/cet.c
@@ -132,6 +132,32 @@ static unsigned long shstk_mmap(unsigned long addr, unsigned long len)
return addr;
}
+int cet_alloc_shstk(unsigned long *arg)
+{
+ unsigned long len = *arg;
+ unsigned long addr;
+ unsigned long token;
+ unsigned long ssp;
+
+ addr = shstk_mmap(0, len);
+ if (addr >= TASK_SIZE_MAX)
+ return -ENOMEM;
+
+ /* Restore token is 8 bytes and aligned to 8 bytes */
+ ssp = addr + len;
+ token = ssp;
+
+ if (!in_ia32_syscall())
+ token |= 1;
+ ssp -=8;
+
+ if (write_user_shstk_64(ssp, token))
+ return -EINVAL;
+
+ *arg = addr;
+ return 0;
+}
+
int cet_setup_shstk(void)
{
unsigned long addr, size;
diff --git a/arch/x86/kernel/cet_prctl.c b/arch/x86/kernel/cet_prctl.c
new file mode 100644
index 000000000000..86bb78ae656d
--- /dev/null
+++ b/arch/x86/kernel/cet_prctl.c
@@ -0,0 +1,141 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <linux/errno.h>
+#include <linux/uaccess.h>
+#include <linux/prctl.h>
+#include <linux/compat.h>
+#include <asm/processor.h>
+#include <asm/prctl.h>
+#include <asm/elf.h>
+#include <asm/elf_property.h>
+#include <asm/cet.h>
+
+/* See Documentation/x86/intel_cet.txt. */
+
+static int handle_get_status(unsigned long arg2)
+{
+ unsigned int features = 0;
+ unsigned long shstk_base, shstk_size;
+
+ if (current->thread.cet.shstk_enabled)
+ features |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
+ if (current->thread.cet.ibt_enabled)
+ features |= GNU_PROPERTY_X86_FEATURE_1_IBT;
+
+ shstk_base = current->thread.cet.shstk_base;
+ shstk_size = current->thread.cet.shstk_size;
+
+ if (in_ia32_syscall()) {
+ unsigned int buf[3];
+
+ buf[0] = features;
+ buf[1] = (unsigned int)shstk_base;
+ buf[2] = (unsigned int)shstk_size;
+ return copy_to_user((unsigned int __user *)arg2, buf,
+ sizeof(buf));
+ } else {
+ unsigned long buf[3];
+
+ buf[0] = (unsigned long)features;
+ buf[1] = shstk_base;
+ buf[2] = shstk_size;
+ return copy_to_user((unsigned long __user *)arg2, buf,
+ sizeof(buf));
+ }
+}
+
+static int handle_alloc_shstk(unsigned long arg2)
+{
+ int err = 0;
+ unsigned long shstk_size = 0;
+
+ if (in_ia32_syscall()) {
+ unsigned int size;
+
+ err = get_user(size, (unsigned int __user *)arg2);
+ if (!err)
+ shstk_size = size;
+ } else {
+ err = get_user(shstk_size, (unsigned long __user *)arg2);
+ }
+
+ if (err)
+ return -EFAULT;
+
+ err = cet_alloc_shstk(&shstk_size);
+ if (err)
+ return -err;
+
+ if (in_ia32_syscall()) {
+ if (put_user(shstk_size, (unsigned int __user *)arg2))
+ return -EFAULT;
+ } else {
+ if (put_user(shstk_size, (unsigned long __user *)arg2))
+ return -EFAULT;
+ }
+ return 0;
+}
+
+static int handle_bitmap(unsigned long arg2)
+{
+ unsigned long addr, size;
+
+ if (current->thread.cet.ibt_enabled) {
+ if (!current->thread.cet.ibt_bitmap_addr)
+ cet_setup_ibt_bitmap();
+ addr = current->thread.cet.ibt_bitmap_addr;
+ size = current->thread.cet.ibt_bitmap_size;
+ } else {
+ addr = 0;
+ size = 0;
+ }
+
+ if (in_compat_syscall()) {
+ if (put_user(addr, (unsigned int __user *)arg2) ||
+ put_user(size, (unsigned int __user *)arg2 + 1))
+ return -EFAULT;
+ } else {
+ if (put_user(addr, (unsigned long __user *)arg2) ||
+ put_user(size, (unsigned long __user *)arg2 + 1))
+ return -EFAULT;
+ }
+ return 0;
+}
+
+int prctl_cet(int option, unsigned long arg2)
+{
+ if (!cpu_feature_enabled(X86_FEATURE_SHSTK) &&
+ !cpu_feature_enabled(X86_FEATURE_IBT))
+ return -EINVAL;
+
+ switch (option) {
+ case ARCH_CET_STATUS:
+ return handle_get_status(arg2);
+
+ case ARCH_CET_DISABLE:
+ if (current->thread.cet.locked)
+ return -EPERM;
+ if (arg2 & GNU_PROPERTY_X86_FEATURE_1_SHSTK)
+ cet_disable_free_shstk(current);
+ if (arg2 & GNU_PROPERTY_X86_FEATURE_1_IBT)
+ cet_disable_ibt();
+
+ return 0;
+
+ case ARCH_CET_LOCK:
+ current->thread.cet.locked = 1;
+ return 0;
+
+ case ARCH_CET_ALLOC_SHSTK:
+ return handle_alloc_shstk(arg2);
+
+ /*
+ * Allocate legacy bitmap and return address & size to user.
+ */
+ case ARCH_CET_LEGACY_BITMAP:
+ return handle_bitmap(arg2);
+
+ default:
+ return -EINVAL;
+ }
+}
diff --git a/arch/x86/kernel/elf.c b/arch/x86/kernel/elf.c
index 42e08d3b573e..3d4934fdac7f 100644
--- a/arch/x86/kernel/elf.c
+++ b/arch/x86/kernel/elf.c
@@ -8,7 +8,10 @@
#include <asm/cet.h>
#include <asm/elf_property.h>
+#include <asm/prctl.h>
+#include <asm/processor.h>
#include <uapi/linux/elf-em.h>
+#include <uapi/linux/prctl.h>
#include <linux/binfmts.h>
#include <linux/elf.h>
#include <linux/slab.h>
@@ -255,6 +258,7 @@ int arch_setup_features(void *ehdr_p, void *phdr_p,
current->thread.cet.ibt_enabled = 0;
current->thread.cet.ibt_bitmap_addr = 0;
current->thread.cet.ibt_bitmap_size = 0;
+ current->thread.cet.locked = 0;
if (cpu_feature_enabled(X86_FEATURE_SHSTK)) {
if (shstk) {
err = cet_setup_shstk();
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 43a57d284a22..259b92664981 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -795,6 +795,12 @@ long do_arch_prctl_common(struct task_struct *task, int option,
return get_cpuid_mode();
case ARCH_SET_CPUID:
return set_cpuid_mode(task, cpuid_enabled);
+ case ARCH_CET_STATUS:
+ case ARCH_CET_DISABLE:
+ case ARCH_CET_LOCK:
+ case ARCH_CET_ALLOC_SHSTK:
+ case ARCH_CET_LEGACY_BITMAP:
+ return prctl_cet(option, cpuid_enabled);
}
return -EINVAL;
--
2.17.1
^ permalink raw reply related
* [RFC PATCH v2 26/27] x86/cet/shstk: Handle thread shadow stack
From: Yu-cheng Yu @ 2018-07-10 22:26 UTC (permalink / raw)
To: x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar, linux-kernel,
linux-doc, linux-mm, linux-arch, linux-api, Arnd Bergmann,
Andy Lutomirski, Balbir Singh, Cyrill Gorcunov, Dave Hansen,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek
Cc: Yu-cheng Yu
In-Reply-To: <20180710222639.8241-1-yu-cheng.yu@intel.com>
The shadow stack for clone/fork is handled as the following:
(1) If ((clone_flags & (CLONE_VFORK | CLONE_VM)) == CLONE_VM),
the kernel allocates (and frees on thread exit) a new SHSTK
for the child.
It is possible for the kernel to complete the clone syscall
and set the child's SHSTK pointer to NULL and let the child
thread allocate a SHSTK for itself. There are two issues
in this approach: It is not compatible with existing code
that does inline syscall and it cannot handle signals before
the child can successfully allocate a SHSTK.
(2) For (clone_flags & CLONE_VFORK), the child uses the existing
SHSTK.
(3) For all other cases, the SHSTK is copied/reused whenever the
parent or the child does a call/ret.
This patch handles cases (1) & (2). Case (3) is handled in
the SHSTK page fault patches.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/include/asm/cet.h | 2 ++
arch/x86/include/asm/mmu_context.h | 3 +++
arch/x86/kernel/cet.c | 33 ++++++++++++++++++++++++++++++
arch/x86/kernel/process.c | 1 +
arch/x86/kernel/process_64.c | 7 +++++++
5 files changed, 46 insertions(+)
diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h
index 71da2cccba16..d5737f3346f2 100644
--- a/arch/x86/include/asm/cet.h
+++ b/arch/x86/include/asm/cet.h
@@ -20,6 +20,7 @@ struct cet_status {
#ifdef CONFIG_X86_INTEL_CET
int cet_setup_shstk(void);
+int cet_setup_thread_shstk(struct task_struct *p);
void cet_disable_shstk(void);
void cet_disable_free_shstk(struct task_struct *p);
int cet_restore_signal(unsigned long ssp);
@@ -29,6 +30,7 @@ int cet_setup_ibt_bitmap(void);
void cet_disable_ibt(void);
#else
static inline int cet_setup_shstk(void) { return 0; }
+static inline int cet_setup_thread_shstk(struct task_struct *p) { return 0; }
static inline void cet_disable_shstk(void) {}
static inline void cet_disable_free_shstk(struct task_struct *p) {}
static inline int cet_restore_signal(unsigned long ssp) { return 0; }
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index bbc796eb0a3b..662755048598 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -13,6 +13,7 @@
#include <asm/tlbflush.h>
#include <asm/paravirt.h>
#include <asm/mpx.h>
+#include <asm/cet.h>
extern atomic64_t last_mm_ctx_id;
@@ -228,6 +229,8 @@ do { \
#else
#define deactivate_mm(tsk, mm) \
do { \
+ if (!tsk->vfork_done) \
+ cet_disable_free_shstk(tsk); \
load_gs_index(0); \
loadsegment(fs, 0); \
} while (0)
diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c
index 8bbd63e1a2ba..2a366a5ccf20 100644
--- a/arch/x86/kernel/cet.c
+++ b/arch/x86/kernel/cet.c
@@ -155,6 +155,39 @@ int cet_setup_shstk(void)
return 0;
}
+int cet_setup_thread_shstk(struct task_struct *tsk)
+{
+ unsigned long addr, size;
+ struct cet_user_state *state;
+
+ if (!current->thread.cet.shstk_enabled)
+ return 0;
+
+ state = get_xsave_addr(&tsk->thread.fpu.state.xsave,
+ XFEATURE_MASK_SHSTK_USER);
+
+ if (!state)
+ return -EINVAL;
+
+ size = tsk->thread.cet.shstk_size;
+ if (size == 0)
+ size = in_ia32_syscall() ? SHSTK_SIZE_32:SHSTK_SIZE_64;
+
+ addr = shstk_mmap(0, size);
+
+ if (addr >= TASK_SIZE_MAX) {
+ tsk->thread.cet.shstk_base = 0;
+ tsk->thread.cet.shstk_size = 0;
+ tsk->thread.cet.shstk_enabled = 0;
+ return -ENOMEM;
+ }
+
+ state->user_ssp = (u64)(addr + size - sizeof(u64));
+ tsk->thread.cet.shstk_base = addr;
+ tsk->thread.cet.shstk_size = size;
+ return 0;
+}
+
void cet_disable_shstk(void)
{
u64 r;
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 309ebb7f9d8d..43a57d284a22 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -127,6 +127,7 @@ void exit_thread(struct task_struct *tsk)
free_vm86(t);
+ cet_disable_free_shstk(tsk);
fpu__drop(fpu);
}
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 12bb445fb98d..6e493b0bcedd 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -317,6 +317,13 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
if (sp)
childregs->sp = sp;
+ /* Allocate a new shadow stack for pthread */
+ if ((clone_flags & (CLONE_VFORK | CLONE_VM)) == CLONE_VM) {
+ err = cet_setup_thread_shstk(p);
+ if (err)
+ goto out;
+ }
+
err = -ENOMEM;
if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
p->thread.io_bitmap_ptr = kmemdup(me->thread.io_bitmap_ptr,
--
2.17.1
^ permalink raw reply related
* [RFC PATCH v2 25/27] x86/cet: Add PTRACE interface for CET
From: Yu-cheng Yu @ 2018-07-10 22:26 UTC (permalink / raw)
To: x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar, linux-kernel,
linux-doc, linux-mm, linux-arch, linux-api, Arnd Bergmann,
Andy Lutomirski, Balbir Singh, Cyrill Gorcunov, Dave Hansen,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek
Cc: Yu-cheng Yu
In-Reply-To: <20180710222639.8241-1-yu-cheng.yu@intel.com>
Add PTRACE interface for CET MSRs.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/include/asm/fpu/regset.h | 7 +++---
arch/x86/kernel/fpu/regset.c | 41 +++++++++++++++++++++++++++++++
arch/x86/kernel/ptrace.c | 16 ++++++++++++
include/uapi/linux/elf.h | 1 +
4 files changed, 62 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/fpu/regset.h b/arch/x86/include/asm/fpu/regset.h
index d5bdffb9d27f..edad0d889084 100644
--- a/arch/x86/include/asm/fpu/regset.h
+++ b/arch/x86/include/asm/fpu/regset.h
@@ -7,11 +7,12 @@
#include <linux/regset.h>
-extern user_regset_active_fn regset_fpregs_active, regset_xregset_fpregs_active;
+extern user_regset_active_fn regset_fpregs_active, regset_xregset_fpregs_active,
+ cetregs_active;
extern user_regset_get_fn fpregs_get, xfpregs_get, fpregs_soft_get,
- xstateregs_get;
+ xstateregs_get, cetregs_get;
extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set,
- xstateregs_set;
+ xstateregs_set, cetregs_set;
/*
* xstateregs_active == regset_fpregs_active. Please refer to the comment
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index bc02f5144b95..7008eb084d36 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -160,6 +160,47 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
return ret;
}
+int cetregs_active(struct task_struct *target, const struct user_regset *regset)
+{
+#ifdef CONFIG_X86_INTEL_CET
+ if (target->thread.cet.shstk_enabled || target->thread.cet.ibt_enabled)
+ return regset->n;
+#endif
+ return 0;
+}
+
+int cetregs_get(struct task_struct *target, const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ void *kbuf, void __user *ubuf)
+{
+ struct fpu *fpu = &target->thread.fpu;
+ struct cet_user_state *cetregs;
+
+ if (!boot_cpu_has(X86_FEATURE_SHSTK))
+ return -ENODEV;
+
+ cetregs = get_xsave_addr(&fpu->state.xsave, XFEATURE_MASK_SHSTK_USER);
+
+ fpu__prepare_read(fpu);
+ return user_regset_copyout(&pos, &count, &kbuf, &ubuf, cetregs, 0, -1);
+}
+
+int cetregs_set(struct task_struct *target, const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ const void *kbuf, const void __user *ubuf)
+{
+ struct fpu *fpu = &target->thread.fpu;
+ struct cet_user_state *cetregs;
+
+ if (!boot_cpu_has(X86_FEATURE_SHSTK))
+ return -ENODEV;
+
+ cetregs = get_xsave_addr(&fpu->state.xsave, XFEATURE_MASK_SHSTK_USER);
+
+ fpu__prepare_write(fpu);
+ return user_regset_copyin(&pos, &count, &kbuf, &ubuf, cetregs, 0, -1);
+}
+
#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
/*
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index e2ee403865eb..ac2bc3a18427 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -49,7 +49,9 @@ enum x86_regset {
REGSET_IOPERM64 = REGSET_XFP,
REGSET_XSTATE,
REGSET_TLS,
+ REGSET_CET64 = REGSET_TLS,
REGSET_IOPERM32,
+ REGSET_CET32,
};
struct pt_regs_offset {
@@ -1276,6 +1278,13 @@ static struct user_regset x86_64_regsets[] __ro_after_init = {
.size = sizeof(long), .align = sizeof(long),
.active = ioperm_active, .get = ioperm_get
},
+ [REGSET_CET64] = {
+ .core_note_type = NT_X86_CET,
+ .n = sizeof(struct cet_user_state) / sizeof(u64),
+ .size = sizeof(u64), .align = sizeof(u64),
+ .active = cetregs_active, .get = cetregs_get,
+ .set = cetregs_set
+ },
};
static const struct user_regset_view user_x86_64_view = {
@@ -1331,6 +1340,13 @@ static struct user_regset x86_32_regsets[] __ro_after_init = {
.size = sizeof(u32), .align = sizeof(u32),
.active = ioperm_active, .get = ioperm_get
},
+ [REGSET_CET32] = {
+ .core_note_type = NT_X86_CET,
+ .n = sizeof(struct cet_user_state) / sizeof(u64),
+ .size = sizeof(u64), .align = sizeof(u64),
+ .active = cetregs_active, .get = cetregs_get,
+ .set = cetregs_set
+ },
};
static const struct user_regset_view user_x86_32_view = {
diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
index dc93982b9664..0898ba719fd7 100644
--- a/include/uapi/linux/elf.h
+++ b/include/uapi/linux/elf.h
@@ -401,6 +401,7 @@ typedef struct elf64_shdr {
#define NT_386_TLS 0x200 /* i386 TLS slots (struct user_desc) */
#define NT_386_IOPERM 0x201 /* x86 io permission bitmap (1=deny) */
#define NT_X86_XSTATE 0x202 /* x86 extended state using xsave */
+#define NT_X86_CET 0x203 /* x86 cet state */
#define NT_S390_HIGH_GPRS 0x300 /* s390 upper register halves */
#define NT_S390_TIMER 0x301 /* s390 timer register */
#define NT_S390_TODCMP 0x302 /* s390 TOD clock comparator register */
--
2.17.1
^ permalink raw reply related
* [RFC PATCH v2 24/27] x86: Insert endbr32/endbr64 to vDSO
From: Yu-cheng Yu @ 2018-07-10 22:26 UTC (permalink / raw)
To: x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar, linux-kernel,
linux-doc, linux-mm, linux-arch, linux-api, Arnd Bergmann,
Andy Lutomirski, Balbir Singh, Cyrill Gorcunov, Dave Hansen,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek
In-Reply-To: <20180710222639.8241-1-yu-cheng.yu@intel.com>
From: "H.J. Lu" <hjl.tools@gmail.com>
When Intel indirect branch tracking is enabled, functions in vDSO which
may be called indirectly must have endbr32 or endbr64 as the first
instruction. Compiler must support -fcf-protection=branch so that it
can be used to compile vDSO.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
---
arch/x86/entry/vdso/.gitignore | 4 ++++
arch/x86/entry/vdso/Makefile | 12 +++++++++++-
arch/x86/entry/vdso/vdso-layout.lds.S | 1 +
3 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/arch/x86/entry/vdso/.gitignore b/arch/x86/entry/vdso/.gitignore
index aae8ffdd5880..552941fdfae0 100644
--- a/arch/x86/entry/vdso/.gitignore
+++ b/arch/x86/entry/vdso/.gitignore
@@ -5,3 +5,7 @@ vdso32-sysenter-syms.lds
vdso32-int80-syms.lds
vdso-image-*.c
vdso2c
+vclock_gettime.S
+vgetcpu.S
+vclock_gettime.asm
+vgetcpu.asm
diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 261802b1cc50..d49548ebec6f 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -108,13 +108,17 @@ vobjx32s := $(foreach F,$(vobjx32s-y),$(obj)/$F)
# Convert 64bit object file to x32 for x32 vDSO.
quiet_cmd_x32 = X32 $@
- cmd_x32 = $(OBJCOPY) -O elf32-x86-64 $< $@
+ cmd_x32 = $(OBJCOPY) -R .note.gnu.property -O elf32-x86-64 $< $@
$(obj)/%-x32.o: $(obj)/%.o FORCE
$(call if_changed,x32)
targets += vdsox32.lds $(vobjx32s-y)
+ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER
+ $(obj)/vclock_gettime.o $(obj)/vgetcpu.o $(obj)/vdso32/vclock_gettime.o: KBUILD_CFLAGS += -fcf-protection=branch
+endif
+
$(obj)/%.so: OBJCOPYFLAGS := -S
$(obj)/%.so: $(obj)/%.so.dbg
$(call if_changed,objcopy)
@@ -164,6 +168,12 @@ quiet_cmd_vdso = VDSO $@
VDSO_LDFLAGS = -fPIC -shared $(call cc-ldoption, -Wl$(comma)--hash-style=both) \
$(call cc-ldoption, -Wl$(comma)--build-id) -Wl,-Bsymbolic $(LTO_CFLAGS)
+ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER
+ VDSO_LDFLAGS += $(call cc-ldoption, -Wl$(comma)-z$(comma)ibt)
+endif
+ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER
+ VDSO_LDFLAGS += $(call cc-ldoption, -Wl$(comma)-z$(comma)shstk)
+endif
GCOV_PROFILE := n
#
diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S
index acfd5ba7d943..cabaeedfed78 100644
--- a/arch/x86/entry/vdso/vdso-layout.lds.S
+++ b/arch/x86/entry/vdso/vdso-layout.lds.S
@@ -74,6 +74,7 @@ SECTIONS
.fake_shstrtab : { *(.fake_shstrtab) } :text
+ .note.gnu.property : { *(.note.gnu.property) } :text :note
.note : { *(.note.*) } :text :note
.eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
--
2.17.1
^ permalink raw reply related
* [RFC PATCH v2 23/27] mm/mmap: Add IBT bitmap size to address space limit check
From: Yu-cheng Yu @ 2018-07-10 22:26 UTC (permalink / raw)
To: x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar, linux-kernel,
linux-doc, linux-mm, linux-arch, linux-api, Arnd Bergmann,
Andy Lutomirski, Balbir Singh, Cyrill Gorcunov, Dave Hansen,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek
Cc: Yu-cheng Yu
In-Reply-To: <20180710222639.8241-1-yu-cheng.yu@intel.com>
The indirect branch tracking legacy bitmap takes a large address
space. This causes may_expand_vm() failure on the address limit
check. For a IBT-enabled task, add the bitmap size to the
address limit.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/include/uapi/asm/resource.h | 5 +++++
include/uapi/asm-generic/resource.h | 3 +++
mm/mmap.c | 12 +++++++++++-
3 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/uapi/asm/resource.h b/arch/x86/include/uapi/asm/resource.h
index 04bc4db8921b..0741b2a6101a 100644
--- a/arch/x86/include/uapi/asm/resource.h
+++ b/arch/x86/include/uapi/asm/resource.h
@@ -1 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+#ifdef CONFIG_X86_INTEL_CET
+#define rlimit_as_extra() current->thread.cet.ibt_bitmap_size
+#endif
+
#include <asm-generic/resource.h>
diff --git a/include/uapi/asm-generic/resource.h b/include/uapi/asm-generic/resource.h
index f12db7a0da64..8a7608a09700 100644
--- a/include/uapi/asm-generic/resource.h
+++ b/include/uapi/asm-generic/resource.h
@@ -58,5 +58,8 @@
# define RLIM_INFINITY (~0UL)
#endif
+#ifndef rlimit_as_extra
+#define rlimit_as_extra() 0
+#endif
#endif /* _UAPI_ASM_GENERIC_RESOURCE_H */
diff --git a/mm/mmap.c b/mm/mmap.c
index d1eb87ef4b1a..fad41b291ae1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3242,7 +3242,17 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
*/
bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
{
- if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
+ unsigned long as_limit = rlimit(RLIMIT_AS);
+ unsigned long as_limit_plus = as_limit + rlimit_as_extra();
+
+ /* as_limit_plus overflowed */
+ if (as_limit_plus < as_limit)
+ as_limit_plus = RLIM_INFINITY;
+
+ if (as_limit_plus > as_limit)
+ as_limit = as_limit_plus;
+
+ if (mm->total_vm + npages > as_limit >> PAGE_SHIFT)
return false;
if (is_data_mapping(flags) &&
--
2.17.1
^ permalink raw reply related
* [RFC PATCH v2 22/27] x86/cet/ibt: User-mode indirect branch tracking support
From: Yu-cheng Yu @ 2018-07-10 22:26 UTC (permalink / raw)
To: x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar, linux-kernel,
linux-doc, linux-mm, linux-arch, linux-api, Arnd Bergmann,
Andy Lutomirski, Balbir Singh, Cyrill Gorcunov, Dave Hansen,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek
Cc: Yu-cheng Yu
In-Reply-To: <20180710222639.8241-1-yu-cheng.yu@intel.com>
Add user-mode indirect branch tracking enabling/disabling
and supporting routines.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/include/asm/cet.h | 8 +++
arch/x86/include/asm/disabled-features.h | 8 ++-
arch/x86/kernel/cet.c | 73 ++++++++++++++++++++++++
arch/x86/kernel/cpu/common.c | 20 ++++++-
arch/x86/kernel/elf.c | 16 +++++-
arch/x86/kernel/process.c | 1 +
6 files changed, 123 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h
index d9ae3d86cdd7..71da2cccba16 100644
--- a/arch/x86/include/asm/cet.h
+++ b/arch/x86/include/asm/cet.h
@@ -12,7 +12,10 @@ struct task_struct;
struct cet_status {
unsigned long shstk_base;
unsigned long shstk_size;
+ unsigned long ibt_bitmap_addr;
+ unsigned long ibt_bitmap_size;
unsigned int shstk_enabled:1;
+ unsigned int ibt_enabled:1;
};
#ifdef CONFIG_X86_INTEL_CET
@@ -21,6 +24,9 @@ void cet_disable_shstk(void);
void cet_disable_free_shstk(struct task_struct *p);
int cet_restore_signal(unsigned long ssp);
int cet_setup_signal(bool ia32, unsigned long rstor, unsigned long *new_ssp);
+int cet_setup_ibt(void);
+int cet_setup_ibt_bitmap(void);
+void cet_disable_ibt(void);
#else
static inline int cet_setup_shstk(void) { return 0; }
static inline void cet_disable_shstk(void) {}
@@ -28,6 +34,8 @@ static inline void cet_disable_free_shstk(struct task_struct *p) {}
static inline int cet_restore_signal(unsigned long ssp) { return 0; }
static inline int cet_setup_signal(bool ia32, unsigned long rstor,
unsigned long *new_ssp) { return 0; }
+static inline int cet_setup_ibt(void) { return 0; }
+static inline void cet_disable_ibt(void) {}
#endif
#endif /* __ASSEMBLY__ */
diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h
index 3624a11e5ba6..ce5bdaf0f1ff 100644
--- a/arch/x86/include/asm/disabled-features.h
+++ b/arch/x86/include/asm/disabled-features.h
@@ -62,6 +62,12 @@
#define DISABLE_SHSTK (1<<(X86_FEATURE_SHSTK & 31))
#endif
+#ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER
+#define DISABLE_IBT 0
+#else
+#define DISABLE_IBT (1<<(X86_FEATURE_IBT & 31))
+#endif
+
/*
* Make sure to add features to the correct mask
*/
@@ -72,7 +78,7 @@
#define DISABLED_MASK4 (DISABLE_PCID)
#define DISABLED_MASK5 0
#define DISABLED_MASK6 0
-#define DISABLED_MASK7 (DISABLE_PTI)
+#define DISABLED_MASK7 (DISABLE_PTI|DISABLE_IBT)
#define DISABLED_MASK8 0
#define DISABLED_MASK9 (DISABLE_MPX)
#define DISABLED_MASK10 0
diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c
index 4eba7790c4e4..8bbd63e1a2ba 100644
--- a/arch/x86/kernel/cet.c
+++ b/arch/x86/kernel/cet.c
@@ -12,6 +12,8 @@
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/sched/signal.h>
+#include <linux/vmalloc.h>
+#include <linux/bitops.h>
#include <asm/msr.h>
#include <asm/user.h>
#include <asm/fpu/xstate.h>
@@ -241,3 +243,74 @@ int cet_setup_signal(bool ia32, unsigned long rstor_addr,
set_shstk_ptr(ssp);
return 0;
}
+
+static unsigned long ibt_mmap(unsigned long addr, unsigned long len)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long populate;
+
+ down_write(&mm->mmap_sem);
+ addr = do_mmap(NULL, addr, len, PROT_READ | PROT_WRITE,
+ MAP_ANONYMOUS | MAP_PRIVATE,
+ VM_DONTDUMP, 0, &populate, NULL);
+ up_write(&mm->mmap_sem);
+
+ if (populate)
+ mm_populate(addr, populate);
+
+ return addr;
+}
+
+int cet_setup_ibt(void)
+{
+ u64 r;
+
+ if (!cpu_feature_enabled(X86_FEATURE_IBT))
+ return -EOPNOTSUPP;
+
+ rdmsrl(MSR_IA32_U_CET, r);
+ r |= (MSR_IA32_CET_ENDBR_EN | MSR_IA32_CET_NO_TRACK_EN);
+ wrmsrl(MSR_IA32_U_CET, r);
+ current->thread.cet.ibt_enabled = 1;
+ return 0;
+}
+
+int cet_setup_ibt_bitmap(void)
+{
+ u64 r;
+ unsigned long bitmap;
+ unsigned long size;
+
+ if (!cpu_feature_enabled(X86_FEATURE_IBT))
+ return -EOPNOTSUPP;
+
+ size = TASK_SIZE_MAX / PAGE_SIZE / BITS_PER_BYTE;
+ bitmap = ibt_mmap(0, size);
+
+ if (bitmap >= TASK_SIZE_MAX)
+ return -ENOMEM;
+
+ bitmap &= PAGE_MASK;
+
+ rdmsrl(MSR_IA32_U_CET, r);
+ r |= (MSR_IA32_CET_LEG_IW_EN | bitmap);
+ wrmsrl(MSR_IA32_U_CET, r);
+
+ current->thread.cet.ibt_bitmap_addr = bitmap;
+ current->thread.cet.ibt_bitmap_size = size;
+ return 0;
+}
+
+void cet_disable_ibt(void)
+{
+ u64 r;
+
+ if (!cpu_feature_enabled(X86_FEATURE_IBT))
+ return;
+
+ rdmsrl(MSR_IA32_U_CET, r);
+ r &= ~(MSR_IA32_CET_ENDBR_EN | MSR_IA32_CET_LEG_IW_EN |
+ MSR_IA32_CET_NO_TRACK_EN);
+ wrmsrl(MSR_IA32_U_CET, r);
+ current->thread.cet.ibt_enabled = 0;
+}
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 705467839ce8..c609c9ce5691 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -413,7 +413,8 @@ __setup("nopku", setup_disable_pku);
static __always_inline void setup_cet(struct cpuinfo_x86 *c)
{
- if (cpu_feature_enabled(X86_FEATURE_SHSTK))
+ if (cpu_feature_enabled(X86_FEATURE_SHSTK) ||
+ cpu_feature_enabled(X86_FEATURE_IBT))
cr4_set_bits(X86_CR4_CET);
}
@@ -434,6 +435,23 @@ static __init int setup_disable_shstk(char *s)
__setup("no_cet_shstk", setup_disable_shstk);
#endif
+#ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER
+static __init int setup_disable_ibt(char *s)
+{
+ /* require an exact match without trailing characters */
+ if (strlen(s))
+ return 0;
+
+ if (!boot_cpu_has(X86_FEATURE_IBT))
+ return 1;
+
+ setup_clear_cpu_cap(X86_FEATURE_IBT);
+ pr_info("x86: 'no_cet_ibt' specified, disabling Branch Tracking\n");
+ return 1;
+}
+__setup("no_cet_ibt", setup_disable_ibt);
+#endif
+
/*
* Some CPU features depend on higher CPUID levels, which may not always
* be available due to CPUID level capping or broken virtualization
diff --git a/arch/x86/kernel/elf.c b/arch/x86/kernel/elf.c
index 233f6dad9c1f..42e08d3b573e 100644
--- a/arch/x86/kernel/elf.c
+++ b/arch/x86/kernel/elf.c
@@ -15,6 +15,7 @@
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/string.h>
+#include <linux/compat.h>
/*
* The .note.gnu.property layout:
@@ -222,7 +223,8 @@ int arch_setup_features(void *ehdr_p, void *phdr_p,
struct elf64_hdr *ehdr64 = ehdr_p;
- if (!cpu_feature_enabled(X86_FEATURE_SHSTK))
+ if (!cpu_feature_enabled(X86_FEATURE_SHSTK) &&
+ !cpu_feature_enabled(X86_FEATURE_IBT))
return 0;
if (ehdr64->e_ident[EI_CLASS] == ELFCLASS64) {
@@ -250,6 +252,9 @@ int arch_setup_features(void *ehdr_p, void *phdr_p,
current->thread.cet.shstk_enabled = 0;
current->thread.cet.shstk_base = 0;
current->thread.cet.shstk_size = 0;
+ current->thread.cet.ibt_enabled = 0;
+ current->thread.cet.ibt_bitmap_addr = 0;
+ current->thread.cet.ibt_bitmap_size = 0;
if (cpu_feature_enabled(X86_FEATURE_SHSTK)) {
if (shstk) {
err = cet_setup_shstk();
@@ -257,6 +262,15 @@ int arch_setup_features(void *ehdr_p, void *phdr_p,
goto out;
}
}
+
+ if (cpu_feature_enabled(X86_FEATURE_IBT)) {
+ if (ibt) {
+ err = cet_setup_ibt();
+ if (err < 0)
+ goto out;
+ }
+ }
+
out:
return err;
}
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index b3b0b482983a..309ebb7f9d8d 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -138,6 +138,7 @@ void flush_thread(void)
memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
cet_disable_shstk();
+ cet_disable_ibt();
fpu__clear(&tsk->thread.fpu);
}
--
2.17.1
^ permalink raw reply related
* [RFC PATCH v2 21/27] x86/cet/ibt: Add Kconfig option for user-mode Indirect Branch Tracking
From: Yu-cheng Yu @ 2018-07-10 22:26 UTC (permalink / raw)
To: x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar, linux-kernel,
linux-doc, linux-mm, linux-arch, linux-api, Arnd Bergmann,
Andy Lutomirski, Balbir Singh, Cyrill Gorcunov, Dave Hansen,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek
Cc: Yu-cheng Yu
In-Reply-To: <20180710222639.8241-1-yu-cheng.yu@intel.com>
The user-mode indirect branch tracking support is done mostly by
GCC to insert ENDBR64/ENDBR32 instructions at branch targets.
The kernel provides CPUID enumeration, feature MSR setup and
the allocation of legacy bitmap.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/Kconfig | 12 ++++++++++++
arch/x86/Makefile | 7 +++++++
2 files changed, 19 insertions(+)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 768343768643..01de9743efe6 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1945,6 +1945,18 @@ config X86_INTEL_SHADOW_STACK_USER
If unsure, say y.
+config X86_INTEL_BRANCH_TRACKING_USER
+ prompt "Intel Indirect Branch Tracking for user-mode"
+ def_bool n
+ depends on CPU_SUP_INTEL && X86_64
+ select X86_INTEL_CET
+ select ARCH_HAS_PROGRAM_PROPERTIES
+ ---help---
+ Indirect Branch Tracking provides hardware protection against return-/jmp-
+ oriented programing attacks.
+
+ If unsure, say y
+
config EFI
bool "EFI runtime service support"
depends on ACPI
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index ad1314e5ef65..a7913de34866 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -164,6 +164,13 @@ ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER
endif
endif
+# Check compiler ibt support
+ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER
+ ifeq ($(call cc-option-yn, -fcf-protection=branch), n)
+ $(error CONFIG_X86_INTEL_BRANCH_TRACKING_USER not supported by compiler)
+ endif
+endif
+
#
# If the function graph tracer is used with mcount instead of fentry,
# '-maccumulate-outgoing-args' is needed to prevent a GCC bug
--
2.17.1
^ permalink raw reply related
* [RFC PATCH v2 20/27] x86/cet/shstk: ELF header parsing of CET
From: Yu-cheng Yu @ 2018-07-10 22:26 UTC (permalink / raw)
To: x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar, linux-kernel,
linux-doc, linux-mm, linux-arch, linux-api, Arnd Bergmann,
Andy Lutomirski, Balbir Singh, Cyrill Gorcunov, Dave Hansen,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek
Cc: Yu-cheng Yu
In-Reply-To: <20180710222639.8241-1-yu-cheng.yu@intel.com>
Look in .note.gnu.property of an ELF file and check if shadow stack needs
to be enabled for the task.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/Kconfig | 4 +
arch/x86/include/asm/elf.h | 5 +
arch/x86/include/uapi/asm/elf_property.h | 16 ++
arch/x86/kernel/Makefile | 2 +
arch/x86/kernel/elf.c | 262 +++++++++++++++++++++++
fs/binfmt_elf.c | 16 ++
include/uapi/linux/elf.h | 1 +
7 files changed, 306 insertions(+)
create mode 100644 arch/x86/include/uapi/asm/elf_property.h
create mode 100644 arch/x86/kernel/elf.c
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 44af5e1aaa4a..768343768643 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1923,12 +1923,16 @@ config X86_INTEL_CET
config ARCH_HAS_SHSTK
def_bool n
+config ARCH_HAS_PROGRAM_PROPERTIES
+ def_bool n
+
config X86_INTEL_SHADOW_STACK_USER
prompt "Intel Shadow Stack for user-mode"
def_bool n
depends on CPU_SUP_INTEL && X86_64
select X86_INTEL_CET
select ARCH_HAS_SHSTK
+ select ARCH_HAS_PROGRAM_PROPERTIES
---help---
Shadow stack provides hardware protection against program stack
corruption. Only when all the following are true will an application
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 0d157d2a1e2a..5b5f169c5c07 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -382,4 +382,9 @@ struct va_alignment {
extern struct va_alignment va_align;
extern unsigned long align_vdso_addr(unsigned long);
+
+#ifdef CONFIG_ARCH_HAS_PROGRAM_PROPERTIES
+extern int arch_setup_features(void *ehdr, void *phdr, struct file *file,
+ bool interp);
+#endif
#endif /* _ASM_X86_ELF_H */
diff --git a/arch/x86/include/uapi/asm/elf_property.h b/arch/x86/include/uapi/asm/elf_property.h
new file mode 100644
index 000000000000..343a871b8fc1
--- /dev/null
+++ b/arch/x86/include/uapi/asm/elf_property.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _UAPI_ASM_X86_ELF_PROPERTY_H
+#define _UAPI_ASM_X86_ELF_PROPERTY_H
+
+/*
+ * pr_type
+ */
+#define GNU_PROPERTY_X86_FEATURE_1_AND (0xc0000002)
+
+/*
+ * Bits for GNU_PROPERTY_X86_FEATURE_1_AND
+ */
+#define GNU_PROPERTY_X86_FEATURE_1_SHSTK (0x00000002)
+#define GNU_PROPERTY_X86_FEATURE_1_IBT (0x00000001)
+
+#endif /* _UAPI_ASM_X86_ELF_PROPERTY_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index fbb2d91fb756..36b14ef410c8 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -141,6 +141,8 @@ obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
obj-$(CONFIG_X86_INTEL_CET) += cet.o
+obj-$(CONFIG_ARCH_HAS_PROGRAM_PROPERTIES) += elf.o
+
###
# 64 bit specific files
ifeq ($(CONFIG_X86_64),y)
diff --git a/arch/x86/kernel/elf.c b/arch/x86/kernel/elf.c
new file mode 100644
index 000000000000..233f6dad9c1f
--- /dev/null
+++ b/arch/x86/kernel/elf.c
@@ -0,0 +1,262 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Look at an ELF file's .note.gnu.property and determine if the file
+ * supports shadow stack and/or indirect branch tracking.
+ * The path from the ELF header to the note section is the following:
+ * elfhdr->elf_phdr->elf_note->property[].
+ */
+
+#include <asm/cet.h>
+#include <asm/elf_property.h>
+#include <uapi/linux/elf-em.h>
+#include <linux/binfmts.h>
+#include <linux/elf.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/string.h>
+
+/*
+ * The .note.gnu.property layout:
+ *
+ * struct elf_note {
+ * u32 n_namesz; --> sizeof(n_name[]); always (4)
+ * u32 n_ndescsz;--> sizeof(property[])
+ * u32 n_type; --> always NT_GNU_PROPERTY_TYPE_0
+ * };
+ *
+ * char n_name[4]; --> always 'GNU\0'
+ *
+ * struct {
+ * u32 pr_type;
+ * u32 pr_datasz;--> sizeof(pr_data[])
+ * u8 pr_data[pr_datasz];
+ * } property[];
+ */
+
+#define ELF_NOTE_DESC_OFFSET(n, align) \
+ round_up(sizeof(*n) + n->n_namesz, (align))
+
+#define ELF_NOTE_NEXT_OFFSET(n, align) \
+ round_up(ELF_NOTE_DESC_OFFSET(n, align) + n->n_descsz, (align))
+
+#define NOTE_PROPERTY_TYPE_0(n) \
+ ((n->n_namesz == 4) && (memcmp(n + 1, "GNU", 4) == 0) && \
+ (n->n_type == NT_GNU_PROPERTY_TYPE_0))
+
+#define NOTE_SIZE_BAD(n, align, max) \
+ ((n->n_descsz < 8) || ((n->n_descsz % align) != 0) || \
+ (((u8 *)(n + 1) + 4 + n->n_descsz) > (max)))
+
+/*
+ * Go through the property array and look for the one
+ * with pr_type of GNU_PROPERTY_X86_FEATURE_1_AND.
+ */
+static u32 find_x86_feature_1(u8 *buf, u32 size, u32 align)
+{
+ u8 *end = buf + size;
+ u8 *ptr = buf;
+
+ while (1) {
+ u32 pr_type, pr_datasz;
+
+ if ((ptr + 4) >= end)
+ break;
+
+ pr_type = *(u32 *)ptr;
+ pr_datasz = *(u32 *)(ptr + 4);
+ ptr += 8;
+
+ if ((ptr + pr_datasz) >= end)
+ break;
+
+ if (pr_type == GNU_PROPERTY_X86_FEATURE_1_AND &&
+ pr_datasz == 4)
+ return *(u32 *)ptr;
+
+ ptr += pr_datasz;
+ }
+ return 0;
+}
+
+static int find_cet(u8 *buf, u32 size, u32 align, int *shstk, int *ibt)
+{
+ struct elf_note *note = (struct elf_note *)buf;
+ *shstk = 0;
+ *ibt = 0;
+
+ /*
+ * Go through the note section and find the note
+ * with n_type of NT_GNU_PROPERTY_TYPE_0.
+ */
+ while ((unsigned long)(note + 1) - (unsigned long)buf < size) {
+ if (NOTE_PROPERTY_TYPE_0(note)) {
+ u32 p;
+
+ if (NOTE_SIZE_BAD(note, align, buf + size))
+ return 0;
+
+ /*
+ * Found the note; look at its property array.
+ */
+ p = find_x86_feature_1((u8 *)(note + 1) + 4,
+ note->n_descsz, align);
+
+ if (p & GNU_PROPERTY_X86_FEATURE_1_SHSTK)
+ *shstk = 1;
+ if (p & GNU_PROPERTY_X86_FEATURE_1_IBT)
+ *ibt = 1;
+ return 1;
+ }
+
+ /*
+ * Note sections like .note.ABI-tag and .note.gnu.build-id
+ * are aligned to 4 bytes in 64-bit ELF objects. So always
+ * use phdr->p_align.
+ */
+ note = (void *)note + ELF_NOTE_NEXT_OFFSET(note, align);
+ }
+
+ return 0;
+}
+
+static int check_pt_note_segment(struct file *file,
+ unsigned long note_size, loff_t *pos,
+ u32 align, int *shstk, int *ibt)
+{
+ int retval;
+ char *note_buf;
+
+ /*
+ * PT_NOTE segment is small. Read at most
+ * PAGE_SIZE.
+ */
+ if (note_size > PAGE_SIZE)
+ note_size = PAGE_SIZE;
+
+ /*
+ * Try to read in the whole PT_NOTE segment.
+ */
+ note_buf = kmalloc(note_size, GFP_KERNEL);
+ if (!note_buf)
+ return -ENOMEM;
+ retval = kernel_read(file, note_buf, note_size, pos);
+ if (retval != note_size) {
+ kfree(note_buf);
+ return (retval < 0) ? retval : -EIO;
+ }
+
+ retval = find_cet(note_buf, note_size, align, shstk, ibt);
+ kfree(note_buf);
+ return retval;
+}
+
+#ifdef CONFIG_COMPAT
+static int check_pt_note_32(struct file *file, struct elf32_phdr *phdr,
+ int phnum, int *shstk, int *ibt)
+{
+ int i;
+ int found = 0;
+
+ /*
+ * Go through all PT_NOTE segments and find NT_GNU_PROPERTY_TYPE_0.
+ */
+ for (i = 0; i < phnum; i++, phdr++) {
+ loff_t pos;
+
+ /*
+ * NT_GNU_PROPERTY_TYPE_0 note is aligned to 4 bytes
+ * in 32-bit binaries.
+ */
+ if ((phdr->p_type != PT_NOTE) || (phdr->p_align != 4))
+ continue;
+
+ pos = phdr->p_offset;
+ found = check_pt_note_segment(file, phdr->p_filesz,
+ &pos, phdr->p_align,
+ shstk, ibt);
+ if (found)
+ break;
+ }
+ return found;
+}
+#endif
+
+#ifdef CONFIG_X86_64
+static int check_pt_note_64(struct file *file, struct elf64_phdr *phdr,
+ int phnum, int *shstk, int *ibt)
+{
+ int found = 0;
+
+ /*
+ * Go through all PT_NOTE segments.
+ */
+ for (; phnum > 0; phnum--, phdr++) {
+ loff_t pos;
+
+ /*
+ * NT_GNU_PROPERTY_TYPE_0 note is aligned to 8 bytes
+ * in 64-bit binaries.
+ */
+ if ((phdr->p_type != PT_NOTE) || (phdr->p_align != 8))
+ continue;
+
+ pos = phdr->p_offset;
+ found = check_pt_note_segment(file, phdr->p_filesz,
+ &pos, phdr->p_align,
+ shstk, ibt);
+
+ if (found)
+ break;
+ }
+ return found;
+}
+#endif
+
+int arch_setup_features(void *ehdr_p, void *phdr_p,
+ struct file *file, bool interp)
+{
+ int err = 0;
+ int shstk = 0;
+ int ibt = 0;
+
+ struct elf64_hdr *ehdr64 = ehdr_p;
+
+ if (!cpu_feature_enabled(X86_FEATURE_SHSTK))
+ return 0;
+
+ if (ehdr64->e_ident[EI_CLASS] == ELFCLASS64) {
+ struct elf64_phdr *phdr64 = phdr_p;
+
+ err = check_pt_note_64(file, phdr64, ehdr64->e_phnum,
+ &shstk, &ibt);
+ if (err < 0)
+ goto out;
+ } else {
+#ifdef CONFIG_COMPAT
+ struct elf32_hdr *ehdr32 = ehdr_p;
+
+ if (ehdr32->e_ident[EI_CLASS] == ELFCLASS32) {
+ struct elf32_phdr *phdr32 = phdr_p;
+
+ err = check_pt_note_32(file, phdr32, ehdr32->e_phnum,
+ &shstk, &ibt);
+ if (err < 0)
+ goto out;
+ }
+#endif
+ }
+
+ current->thread.cet.shstk_enabled = 0;
+ current->thread.cet.shstk_base = 0;
+ current->thread.cet.shstk_size = 0;
+ if (cpu_feature_enabled(X86_FEATURE_SHSTK)) {
+ if (shstk) {
+ err = cet_setup_shstk();
+ if (err < 0)
+ goto out;
+ }
+ }
+out:
+ return err;
+}
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 0ac456b52bdd..3395f6a631d5 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1081,6 +1081,22 @@ static int load_elf_binary(struct linux_binprm *bprm)
goto out_free_dentry;
}
+#ifdef CONFIG_ARCH_HAS_PROGRAM_PROPERTIES
+
+ if (interpreter) {
+ retval = arch_setup_features(&loc->interp_elf_ex,
+ interp_elf_phdata,
+ interpreter, true);
+ } else {
+ retval = arch_setup_features(&loc->elf_ex,
+ elf_phdata,
+ bprm->file, false);
+ }
+
+ if (retval < 0)
+ goto out_free_dentry;
+#endif
+
if (elf_interpreter) {
unsigned long interp_map_addr = 0;
diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
index 4e12c423b9fe..dc93982b9664 100644
--- a/include/uapi/linux/elf.h
+++ b/include/uapi/linux/elf.h
@@ -372,6 +372,7 @@ typedef struct elf64_shdr {
#define NT_PRFPREG 2
#define NT_PRPSINFO 3
#define NT_TASKSTRUCT 4
+#define NT_GNU_PROPERTY_TYPE_0 5
#define NT_AUXV 6
/*
* Note to userspace developers: size of NT_SIGINFO note may increase
--
2.17.1
^ permalink raw reply related
* [RFC PATCH v2 19/27] x86/cet/shstk: Signal handling for shadow stack
From: Yu-cheng Yu @ 2018-07-10 22:26 UTC (permalink / raw)
To: x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar, linux-kernel,
linux-doc, linux-mm, linux-arch, linux-api, Arnd Bergmann,
Andy Lutomirski, Balbir Singh, Cyrill Gorcunov, Dave Hansen,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek
Cc: Yu-cheng Yu
In-Reply-To: <20180710222639.8241-1-yu-cheng.yu@intel.com>
When setting up a signal, the kernel creates a shadow stack
restore token at the current SHSTK address and then stores the
token's address in the signal frame, right after the FPU state.
Before restoring a signal, the kernel verifies and then uses the
restore token to set the SHSTK pointer.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/ia32/ia32_signal.c | 13 +++
arch/x86/include/asm/cet.h | 5 ++
arch/x86/include/asm/sighandling.h | 5 ++
arch/x86/include/uapi/asm/sigcontext.h | 17 ++++
arch/x86/kernel/cet.c | 115 +++++++++++++++++++++++++
arch/x86/kernel/signal.c | 96 +++++++++++++++++++++
6 files changed, 251 insertions(+)
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 86b1341cba9a..cea28d2a946e 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -34,6 +34,7 @@
#include <asm/sigframe.h>
#include <asm/sighandling.h>
#include <asm/smap.h>
+#include <asm/cet.h>
/*
* Do a signal return; undo the signal stack.
@@ -108,6 +109,9 @@ static int ia32_restore_sigcontext(struct pt_regs *regs,
err |= fpu__restore_sig(buf, 1);
+ if (!err)
+ err = restore_sigcontext_ext(buf);
+
force_iret();
return err;
@@ -234,6 +238,10 @@ static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
if (fpu->initialized) {
unsigned long fx_aligned, math_size;
+ /* sigcontext extension */
+ if (boot_cpu_has(X86_FEATURE_SHSTK))
+ sp -= (sizeof(struct sc_ext) + 8);
+
sp = fpu__alloc_mathframe(sp, 1, &fx_aligned, &math_size);
*fpstate = (struct _fpstate_32 __user *) sp;
if (copy_fpstate_to_sigframe(*fpstate, (void __user *)fx_aligned,
@@ -277,6 +285,8 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
return -EFAULT;
+ if (setup_sigcontext_ext(ksig, fpstate))
+ return -EFAULT;
if (_COMPAT_NSIG_WORDS > 1) {
if (__copy_to_user(frame->extramask, &set->sig[1],
@@ -384,6 +394,9 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+ if (!err)
+ err = setup_sigcontext_ext(ksig, fpstate);
+
if (err)
return -EFAULT;
diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h
index ad278c520414..d9ae3d86cdd7 100644
--- a/arch/x86/include/asm/cet.h
+++ b/arch/x86/include/asm/cet.h
@@ -19,10 +19,15 @@ struct cet_status {
int cet_setup_shstk(void);
void cet_disable_shstk(void);
void cet_disable_free_shstk(struct task_struct *p);
+int cet_restore_signal(unsigned long ssp);
+int cet_setup_signal(bool ia32, unsigned long rstor, unsigned long *new_ssp);
#else
static inline int cet_setup_shstk(void) { return 0; }
static inline void cet_disable_shstk(void) {}
static inline void cet_disable_free_shstk(struct task_struct *p) {}
+static inline int cet_restore_signal(unsigned long ssp) { return 0; }
+static inline int cet_setup_signal(bool ia32, unsigned long rstor,
+ unsigned long *new_ssp) { return 0; }
#endif
#endif /* __ASSEMBLY__ */
diff --git a/arch/x86/include/asm/sighandling.h b/arch/x86/include/asm/sighandling.h
index bd26834724e5..23014b4082de 100644
--- a/arch/x86/include/asm/sighandling.h
+++ b/arch/x86/include/asm/sighandling.h
@@ -17,4 +17,9 @@ void signal_fault(struct pt_regs *regs, void __user *frame, char *where);
int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
struct pt_regs *regs, unsigned long mask);
+#ifdef CONFIG_X86_64
+int setup_sigcontext_ext(struct ksignal *ksig, void __user *fpu);
+int restore_sigcontext_ext(void __user *fpu);
+#endif
+
#endif /* _ASM_X86_SIGHANDLING_H */
diff --git a/arch/x86/include/uapi/asm/sigcontext.h b/arch/x86/include/uapi/asm/sigcontext.h
index 844d60eb1882..74f5ea5dcd24 100644
--- a/arch/x86/include/uapi/asm/sigcontext.h
+++ b/arch/x86/include/uapi/asm/sigcontext.h
@@ -196,6 +196,23 @@ struct _xstate {
/* New processor state extensions go here: */
};
+#ifdef __x86_64__
+/*
+ * Sigcontext extension (struct sc_ext) is located after
+ * sigcontext->fpstate. Because currently only the shadow
+ * stack pointer is saved there and the shadow stack depends
+ * on XSAVES, we can find sc_ext from sigcontext->fpstate.
+ *
+ * The 64-bit fpstate has a size of fpu_user_xstate_size, plus
+ * FP_XSTATE_MAGIC2_SIZE when XSAVE* is used. The struct sc_ext
+ * is located at the end of sigcontext->fpstate, aligned to 8.
+ */
+struct sc_ext {
+ unsigned long total_size;
+ unsigned long ssp;
+};
+#endif
+
/*
* The 32-bit signal frame:
*/
diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c
index 96bf69db7da7..4eba7790c4e4 100644
--- a/arch/x86/kernel/cet.c
+++ b/arch/x86/kernel/cet.c
@@ -18,6 +18,7 @@
#include <asm/fpu/types.h>
#include <asm/compat.h>
#include <asm/cet.h>
+#include <asm/special_insns.h>
#define SHSTK_SIZE_64 (0x8000 * 8)
#define SHSTK_SIZE_32 (0x8000 * 4)
@@ -49,6 +50,69 @@ static unsigned long get_shstk_addr(void)
return ptr;
}
+/*
+ * Verify the restore token at the address of 'ssp' is
+ * valid and then set shadow stack pointer according to the
+ * token.
+ */
+static int verify_rstor_token(bool ia32, unsigned long ssp,
+ unsigned long *new_ssp)
+{
+ unsigned long token;
+
+ *new_ssp = 0;
+
+ if (!IS_ALIGNED(ssp, 8))
+ return -EINVAL;
+
+ if (get_user(token, (unsigned long __user*)ssp))
+ return -EFAULT;
+
+ /* Is 64-bit mode flag correct? */
+ if (ia32 && (token & 3) != 0)
+ return -EINVAL;
+ else if ((token & 3) != 1)
+ return -EINVAL;
+
+ token &= ~(1UL);
+
+ if ((!ia32 && !IS_ALIGNED(token, 8)) || !IS_ALIGNED(token, 4))
+ return -EINVAL;
+
+ if ((ALIGN_DOWN(token, 8) - 8) != ssp)
+ return -EINVAL;
+
+ *new_ssp = token;
+ return 0;
+}
+
+/*
+ * Create a restore token on the shadow stack.
+ * A token is always 8-byte and aligned to 8.
+ */
+static int create_rstor_token(bool ia32, unsigned long ssp,
+ unsigned long *new_ssp)
+{
+ unsigned long addr;
+
+ *new_ssp = 0;
+
+ if ((!ia32 && !IS_ALIGNED(ssp, 8)) || !IS_ALIGNED(ssp, 4))
+ return -EINVAL;
+
+ addr = ALIGN_DOWN(ssp, 8) - 8;
+
+ /* Is the token for 64-bit? */
+ if (!ia32)
+ ssp |= 1;
+
+ if (write_user_shstk_64(addr, ssp))
+ return -EFAULT;
+
+ *new_ssp = addr;
+ return 0;
+}
+
static unsigned long shstk_mmap(unsigned long addr, unsigned long len)
{
struct mm_struct *mm = current->mm;
@@ -126,3 +190,54 @@ void cet_disable_free_shstk(struct task_struct *tsk)
tsk->thread.cet.shstk_enabled = 0;
}
+
+int cet_restore_signal(unsigned long ssp)
+{
+ unsigned long new_ssp;
+ int err;
+
+ if (!current->thread.cet.shstk_enabled)
+ return 0;
+
+ err = verify_rstor_token(in_ia32_syscall(), ssp, &new_ssp);
+
+ if (err)
+ return err;
+
+ return set_shstk_ptr(new_ssp);
+}
+
+/*
+ * Setup the shadow stack for the signal handler: first,
+ * create a restore token to keep track of the current ssp,
+ * and then the return address of the signal handler.
+ */
+int cet_setup_signal(bool ia32, unsigned long rstor_addr,
+ unsigned long *new_ssp)
+{
+ unsigned long ssp;
+ int err;
+
+ if (!current->thread.cet.shstk_enabled)
+ return 0;
+
+ ssp = get_shstk_addr();
+ err = create_rstor_token(ia32, ssp, new_ssp);
+
+ if (err)
+ return err;
+
+ if (ia32) {
+ ssp = *new_ssp - sizeof(u32);
+ err = write_user_shstk_32(ssp, (unsigned int)rstor_addr);
+ } else {
+ ssp = *new_ssp - sizeof(u64);
+ err = write_user_shstk_64(ssp, rstor_addr);
+ }
+
+ if (err)
+ return err;
+
+ set_shstk_ptr(ssp);
+ return 0;
+}
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 92a3b312a53c..31f45d8d794a 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -46,6 +46,7 @@
#include <asm/sigframe.h>
#include <asm/signal.h>
+#include <asm/cet.h>
#define COPY(x) do { \
get_user_ex(regs->x, &sc->x); \
@@ -152,6 +153,10 @@ static int restore_sigcontext(struct pt_regs *regs,
err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32));
+#ifdef CONFIG_X86_64
+ err |= restore_sigcontext_ext(buf);
+#endif
+
force_iret();
return err;
@@ -266,6 +271,11 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
}
if (fpu->initialized) {
+#ifdef CONFIG_X86_64
+ /* sigcontext extension */
+ if (boot_cpu_has(X86_FEATURE_SHSTK))
+ sp -= sizeof(struct sc_ext) + 8;
+#endif
sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
&buf_fx, &math_size);
*fpstate = (void __user *)sp;
@@ -493,6 +503,9 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+ if (!err)
+ err = setup_sigcontext_ext(ksig, fp);
+
if (err)
return -EFAULT;
@@ -576,6 +589,9 @@ static int x32_setup_rt_frame(struct ksignal *ksig,
regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+ if (!err)
+ err = setup_sigcontext_ext(ksig, fpstate);
+
if (err)
return -EFAULT;
@@ -707,6 +723,86 @@ setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
}
}
+#ifdef CONFIG_X86_64
+static int copy_ext_from_user(struct sc_ext *ext, void __user *fpu)
+{
+ void __user *p;
+
+ if (!fpu)
+ return -EINVAL;
+
+ p = fpu + fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE;
+ p = (void __user *)ALIGN((unsigned long)p, 8);
+
+ if (!access_ok(VERIFY_READ, p, sizeof(*ext)))
+ return -EFAULT;
+
+ if (__copy_from_user(ext, p, sizeof(*ext)))
+ return -EFAULT;
+
+ if (ext->total_size != sizeof(*ext))
+ return -EINVAL;
+ return 0;
+}
+
+static int copy_ext_to_user(void __user *fpu, struct sc_ext *ext)
+{
+ void __user *p;
+
+ if (!fpu)
+ return -EINVAL;
+
+ if (ext->total_size != sizeof(*ext))
+ return -EINVAL;
+
+ p = fpu + fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE;
+ p = (void __user *)ALIGN((unsigned long)p, 8);
+
+ if (!access_ok(VERIFY_WRITE, p, sizeof(*ext)))
+ return -EFAULT;
+
+ if (__copy_to_user(p, ext, sizeof(*ext)))
+ return -EFAULT;
+
+ return 0;
+}
+
+int restore_sigcontext_ext(void __user *fp)
+{
+ int err = 0;
+
+ if (boot_cpu_has(X86_FEATURE_SHSTK) && fp) {
+ struct sc_ext ext = {0, 0};
+
+ err = copy_ext_from_user(&ext, fp);
+
+ if (!err)
+ err = cet_restore_signal(ext.ssp);
+ }
+
+ return err;
+}
+
+int setup_sigcontext_ext(struct ksignal *ksig, void __user *fp)
+{
+ int err = 0;
+
+ if (boot_cpu_has(X86_FEATURE_SHSTK) && fp) {
+ struct sc_ext ext;
+ unsigned long rstor;
+
+ rstor = (unsigned long)ksig->ka.sa.sa_restorer;
+ err = cet_setup_signal(is_ia32_frame(ksig), rstor, &ext.ssp);
+ if (!err) {
+ ext.total_size = sizeof(ext);
+ err = copy_ext_to_user(fp, &ext);
+ }
+ }
+
+ return err;
+}
+#endif
+
static void
handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
--
2.17.1
^ permalink raw reply related
* [RFC PATCH v2 18/27] x86/cet/shstk: Introduce WRUSS instruction
From: Yu-cheng Yu @ 2018-07-10 22:26 UTC (permalink / raw)
To: x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar, linux-kernel,
linux-doc, linux-mm, linux-arch, linux-api, Arnd Bergmann,
Andy Lutomirski, Balbir Singh, Cyrill Gorcunov, Dave Hansen,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek
Cc: Yu-cheng Yu
In-Reply-To: <20180710222639.8241-1-yu-cheng.yu@intel.com>
WRUSS is a new kernel-mode instruction but writes directly
to user shadow stack memory. This is used to construct
a return address on the shadow stack for the signal
handler.
This instruction can fault if the user shadow stack is
invalid shadow stack memory. In that case, the kernel does
fixup.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/include/asm/special_insns.h | 45 +++++++++++++++++++
arch/x86/lib/x86-opcode-map.txt | 2 +-
arch/x86/mm/fault.c | 13 +++++-
tools/objtool/arch/x86/lib/x86-opcode-map.txt | 2 +-
4 files changed, 59 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
index 317fc59b512c..c69d8d6b457f 100644
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -237,6 +237,51 @@ static inline void clwb(volatile void *__p)
: [pax] "a" (p));
}
+#ifdef CONFIG_X86_INTEL_CET
+
+#if defined(CONFIG_IA32_EMULATION) || defined(CONFIG_X86_X32)
+static inline int write_user_shstk_32(unsigned long addr, unsigned int val)
+{
+ int err;
+
+ asm volatile("1: wrussd %[val], (%[addr])\n"
+ "xor %[err], %[err]\n"
+ "2:\n"
+ ".section .fixup,\"ax\"\n"
+ "3: mov $-1, %[err]; jmp 2b\n"
+ ".previous\n"
+ _ASM_EXTABLE(1b, 3b)
+ : [err] "=a" (err)
+ : [val] "S" (val), [addr] "D" (addr));
+
+ return err;
+}
+#else
+static inline int write_user_shstk_32(unsigned long addr, unsigned int val)
+{
+ BUG();
+ return 0;
+}
+#endif
+
+static inline int write_user_shstk_64(unsigned long addr, unsigned long val)
+{
+ int err = 0;
+
+ asm volatile("1: wrussq %[val], (%[addr])\n"
+ "xor %[err], %[err]\n"
+ "2:\n"
+ ".section .fixup,\"ax\"\n"
+ "3: mov $-1, %[err]; jmp 2b\n"
+ ".previous\n"
+ _ASM_EXTABLE(1b, 3b)
+ : [err] "=a" (err)
+ : [val] "S" (val), [addr] "D" (addr));
+
+ return err;
+}
+#endif /* CONFIG_X86_INTEL_CET */
+
#define nop() asm volatile ("nop")
diff --git a/arch/x86/lib/x86-opcode-map.txt b/arch/x86/lib/x86-opcode-map.txt
index e0b85930dd77..72bb7c48a7df 100644
--- a/arch/x86/lib/x86-opcode-map.txt
+++ b/arch/x86/lib/x86-opcode-map.txt
@@ -789,7 +789,7 @@ f0: MOVBE Gy,My | MOVBE Gw,Mw (66) | CRC32 Gd,Eb (F2) | CRC32 Gd,Eb (66&F2)
f1: MOVBE My,Gy | MOVBE Mw,Gw (66) | CRC32 Gd,Ey (F2) | CRC32 Gd,Ew (66&F2)
f2: ANDN Gy,By,Ey (v)
f3: Grp17 (1A)
-f5: BZHI Gy,Ey,By (v) | PEXT Gy,By,Ey (F3),(v) | PDEP Gy,By,Ey (F2),(v)
+f5: BZHI Gy,Ey,By (v) | PEXT Gy,By,Ey (F3),(v) | PDEP Gy,By,Ey (F2),(v) | WRUSS Pq,Qq (66),REX.W
f6: ADCX Gy,Ey (66) | ADOX Gy,Ey (F3) | MULX By,Gy,rDX,Ey (F2),(v)
f7: BEXTR Gy,Ey,By (v) | SHLX Gy,Ey,By (66),(v) | SARX Gy,Ey,By (F3),(v) | SHRX Gy,Ey,By (F2),(v)
EndTable
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index fcd5739151f9..92f178b8b598 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -641,6 +641,17 @@ static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
return 0;
}
+/*
+ * WRUSS is a kernel instrcution and but writes to user
+ * shadow stack memory. When a fault occurs, both
+ * X86_PF_USER and X86_PF_SHSTK are set.
+ */
+static int is_wruss(struct pt_regs *regs, unsigned long error_code)
+{
+ return (((error_code & (X86_PF_USER | X86_PF_SHSTK)) ==
+ (X86_PF_USER | X86_PF_SHSTK)) && !user_mode(regs));
+}
+
static void
show_fault_oops(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
@@ -848,7 +859,7 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
struct task_struct *tsk = current;
/* User mode accesses just cause a SIGSEGV */
- if (error_code & X86_PF_USER) {
+ if ((error_code & X86_PF_USER) && !is_wruss(regs, error_code)) {
/*
* It's possible to have interrupts off here:
*/
diff --git a/tools/objtool/arch/x86/lib/x86-opcode-map.txt b/tools/objtool/arch/x86/lib/x86-opcode-map.txt
index e0b85930dd77..72bb7c48a7df 100644
--- a/tools/objtool/arch/x86/lib/x86-opcode-map.txt
+++ b/tools/objtool/arch/x86/lib/x86-opcode-map.txt
@@ -789,7 +789,7 @@ f0: MOVBE Gy,My | MOVBE Gw,Mw (66) | CRC32 Gd,Eb (F2) | CRC32 Gd,Eb (66&F2)
f1: MOVBE My,Gy | MOVBE Mw,Gw (66) | CRC32 Gd,Ey (F2) | CRC32 Gd,Ew (66&F2)
f2: ANDN Gy,By,Ey (v)
f3: Grp17 (1A)
-f5: BZHI Gy,Ey,By (v) | PEXT Gy,By,Ey (F3),(v) | PDEP Gy,By,Ey (F2),(v)
+f5: BZHI Gy,Ey,By (v) | PEXT Gy,By,Ey (F3),(v) | PDEP Gy,By,Ey (F2),(v) | WRUSS Pq,Qq (66),REX.W
f6: ADCX Gy,Ey (66) | ADOX Gy,Ey (F3) | MULX By,Gy,rDX,Ey (F2),(v)
f7: BEXTR Gy,Ey,By (v) | SHLX Gy,Ey,By (66),(v) | SARX Gy,Ey,By (F3),(v) | SHRX Gy,Ey,By (F2),(v)
EndTable
--
2.17.1
^ permalink raw reply related
* [RFC PATCH v2 17/27] x86/cet/shstk: User-mode shadow stack support
From: Yu-cheng Yu @ 2018-07-10 22:26 UTC (permalink / raw)
To: x86, H. Peter Anvin, Thomas Gleixner, Ingo Molnar, linux-kernel,
linux-doc, linux-mm, linux-arch, linux-api, Arnd Bergmann,
Andy Lutomirski, Balbir Singh, Cyrill Gorcunov, Dave Hansen,
Florian Weimer, H.J. Lu, Jann Horn, Jonathan Corbet, Kees Cook,
Mike Kravetz, Nadav Amit, Oleg Nesterov, Pavel Machek
Cc: Yu-cheng Yu
In-Reply-To: <20180710222639.8241-1-yu-cheng.yu@intel.com>
This patch adds basic shadow stack enabling/disabling routines.
A task's shadow stack is allocated from memory with VM_SHSTK
flag set and read-only protection. The shadow stack is
allocated to a fixed size.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/include/asm/cet.h | 30 ++++++
arch/x86/include/asm/disabled-features.h | 8 +-
arch/x86/include/asm/msr-index.h | 14 +++
arch/x86/include/asm/processor.h | 5 +
arch/x86/kernel/Makefile | 2 +
arch/x86/kernel/cet.c | 128 +++++++++++++++++++++++
arch/x86/kernel/cpu/common.c | 24 +++++
arch/x86/kernel/process.c | 2 +
fs/proc/task_mmu.c | 3 +
9 files changed, 215 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/include/asm/cet.h
create mode 100644 arch/x86/kernel/cet.c
diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h
new file mode 100644
index 000000000000..ad278c520414
--- /dev/null
+++ b/arch/x86/include/asm/cet.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_CET_H
+#define _ASM_X86_CET_H
+
+#ifndef __ASSEMBLY__
+#include <linux/types.h>
+
+struct task_struct;
+/*
+ * Per-thread CET status
+ */
+struct cet_status {
+ unsigned long shstk_base;
+ unsigned long shstk_size;
+ unsigned int shstk_enabled:1;
+};
+
+#ifdef CONFIG_X86_INTEL_CET
+int cet_setup_shstk(void);
+void cet_disable_shstk(void);
+void cet_disable_free_shstk(struct task_struct *p);
+#else
+static inline int cet_setup_shstk(void) { return 0; }
+static inline void cet_disable_shstk(void) {}
+static inline void cet_disable_free_shstk(struct task_struct *p) {}
+#endif
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_X86_CET_H */
diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h
index 33833d1909af..3624a11e5ba6 100644
--- a/arch/x86/include/asm/disabled-features.h
+++ b/arch/x86/include/asm/disabled-features.h
@@ -56,6 +56,12 @@
# define DISABLE_PTI (1 << (X86_FEATURE_PTI & 31))
#endif
+#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER
+#define DISABLE_SHSTK 0
+#else
+#define DISABLE_SHSTK (1<<(X86_FEATURE_SHSTK & 31))
+#endif
+
/*
* Make sure to add features to the correct mask
*/
@@ -75,7 +81,7 @@
#define DISABLED_MASK13 0
#define DISABLED_MASK14 0
#define DISABLED_MASK15 0
-#define DISABLED_MASK16 (DISABLE_PKU|DISABLE_OSPKE|DISABLE_LA57|DISABLE_UMIP)
+#define DISABLED_MASK16 (DISABLE_PKU|DISABLE_OSPKE|DISABLE_LA57|DISABLE_UMIP|DISABLE_SHSTK)
#define DISABLED_MASK17 0
#define DISABLED_MASK18 0
#define DISABLED_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS != 19)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 68b2c3150de1..66849230712e 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -770,4 +770,18 @@
#define MSR_VM_IGNNE 0xc0010115
#define MSR_VM_HSAVE_PA 0xc0010117
+/* Control-flow Enforcement Technology MSRs */
+#define MSR_IA32_U_CET 0x6a0 /* user mode cet setting */
+#define MSR_IA32_S_CET 0x6a2 /* kernel mode cet setting */
+#define MSR_IA32_PL0_SSP 0x6a4 /* kernel shstk pointer */
+#define MSR_IA32_PL3_SSP 0x6a7 /* user shstk pointer */
+#define MSR_IA32_INT_SSP_TAB 0x6a8 /* exception shstk table */
+
+/* MSR_IA32_U_CET and MSR_IA32_S_CET bits */
+#define MSR_IA32_CET_SHSTK_EN 0x0000000000000001
+#define MSR_IA32_CET_WRSS_EN 0x0000000000000002
+#define MSR_IA32_CET_ENDBR_EN 0x0000000000000004
+#define MSR_IA32_CET_LEG_IW_EN 0x0000000000000008
+#define MSR_IA32_CET_NO_TRACK_EN 0x0000000000000010
+
#endif /* _ASM_X86_MSR_INDEX_H */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index cfd29ee8c3da..edf94393bf7e 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -24,6 +24,7 @@ struct vm86;
#include <asm/special_insns.h>
#include <asm/fpu/types.h>
#include <asm/unwind_hints.h>
+#include <asm/cet.h>
#include <linux/personality.h>
#include <linux/cache.h>
@@ -498,6 +499,10 @@ struct thread_struct {
unsigned int sig_on_uaccess_err:1;
unsigned int uaccess_err:1; /* uaccess failed */
+#ifdef CONFIG_X86_INTEL_CET
+ struct cet_status cet;
+#endif
+
/* Floating point and extended processor state */
struct fpu fpu;
/*
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 8824d01c0c35..fbb2d91fb756 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -139,6 +139,8 @@ obj-$(CONFIG_UNWINDER_ORC) += unwind_orc.o
obj-$(CONFIG_UNWINDER_FRAME_POINTER) += unwind_frame.o
obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
+obj-$(CONFIG_X86_INTEL_CET) += cet.o
+
###
# 64 bit specific files
ifeq ($(CONFIG_X86_64),y)
diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c
new file mode 100644
index 000000000000..96bf69db7da7
--- /dev/null
+++ b/arch/x86/kernel/cet.c
@@ -0,0 +1,128 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * cet.c - Control Flow Enforcement (CET)
+ *
+ * Copyright (c) 2018, Intel Corporation.
+ * Yu-cheng Yu <yu-cheng.yu@intel.com>
+ */
+
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/sched/signal.h>
+#include <asm/msr.h>
+#include <asm/user.h>
+#include <asm/fpu/xstate.h>
+#include <asm/fpu/types.h>
+#include <asm/compat.h>
+#include <asm/cet.h>
+
+#define SHSTK_SIZE_64 (0x8000 * 8)
+#define SHSTK_SIZE_32 (0x8000 * 4)
+
+static int set_shstk_ptr(unsigned long addr)
+{
+ u64 r;
+
+ if (!cpu_feature_enabled(X86_FEATURE_SHSTK))
+ return -1;
+
+ if ((addr >= TASK_SIZE_MAX) || (!IS_ALIGNED(addr, 4)))
+ return -1;
+
+ rdmsrl(MSR_IA32_U_CET, r);
+ wrmsrl(MSR_IA32_PL3_SSP, addr);
+ wrmsrl(MSR_IA32_U_CET, r | MSR_IA32_CET_SHSTK_EN);
+ return 0;
+}
+
+static unsigned long get_shstk_addr(void)
+{
+ unsigned long ptr;
+
+ if (!current->thread.cet.shstk_enabled)
+ return 0;
+
+ rdmsrl(MSR_IA32_PL3_SSP, ptr);
+ return ptr;
+}
+
+static unsigned long shstk_mmap(unsigned long addr, unsigned long len)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long populate;
+
+ down_write(&mm->mmap_sem);
+ addr = do_mmap(NULL, addr, len, PROT_READ,
+ MAP_ANONYMOUS | MAP_PRIVATE, VM_SHSTK,
+ 0, &populate, NULL);
+ up_write(&mm->mmap_sem);
+
+ if (populate)
+ mm_populate(addr, populate);
+
+ return addr;
+}
+
+int cet_setup_shstk(void)
+{
+ unsigned long addr, size;
+
+ if (!cpu_feature_enabled(X86_FEATURE_SHSTK))
+ return -EOPNOTSUPP;
+
+ size = in_ia32_syscall() ? SHSTK_SIZE_32:SHSTK_SIZE_64;
+ addr = shstk_mmap(0, size);
+
+ /*
+ * Return actual error from do_mmap().
+ */
+ if (addr >= TASK_SIZE_MAX)
+ return addr;
+
+ set_shstk_ptr(addr + size - sizeof(u64));
+ current->thread.cet.shstk_base = addr;
+ current->thread.cet.shstk_size = size;
+ current->thread.cet.shstk_enabled = 1;
+ return 0;
+}
+
+void cet_disable_shstk(void)
+{
+ u64 r;
+
+ if (!cpu_feature_enabled(X86_FEATURE_SHSTK))
+ return;
+
+ rdmsrl(MSR_IA32_U_CET, r);
+ r &= ~(MSR_IA32_CET_SHSTK_EN);
+ wrmsrl(MSR_IA32_U_CET, r);
+ wrmsrl(MSR_IA32_PL3_SSP, 0);
+ current->thread.cet.shstk_enabled = 0;
+}
+
+void cet_disable_free_shstk(struct task_struct *tsk)
+{
+ if (!cpu_feature_enabled(X86_FEATURE_SHSTK) ||
+ !tsk->thread.cet.shstk_enabled)
+ return;
+
+ if (tsk == current)
+ cet_disable_shstk();
+
+ /*
+ * Free only when tsk is current or shares mm
+ * with current but has its own shstk.
+ */
+ if (tsk->mm && (tsk->mm == current->mm) &&
+ (tsk->thread.cet.shstk_base)) {
+ vm_munmap(tsk->thread.cet.shstk_base,
+ tsk->thread.cet.shstk_size);
+ tsk->thread.cet.shstk_base = 0;
+ tsk->thread.cet.shstk_size = 0;
+ }
+
+ tsk->thread.cet.shstk_enabled = 0;
+}
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index eb4cb3efd20e..705467839ce8 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -411,6 +411,29 @@ static __init int setup_disable_pku(char *arg)
__setup("nopku", setup_disable_pku);
#endif /* CONFIG_X86_64 */
+static __always_inline void setup_cet(struct cpuinfo_x86 *c)
+{
+ if (cpu_feature_enabled(X86_FEATURE_SHSTK))
+ cr4_set_bits(X86_CR4_CET);
+}
+
+#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER
+static __init int setup_disable_shstk(char *s)
+{
+ /* require an exact match without trailing characters */
+ if (strlen(s))
+ return 0;
+
+ if (!boot_cpu_has(X86_FEATURE_SHSTK))
+ return 1;
+
+ setup_clear_cpu_cap(X86_FEATURE_SHSTK);
+ pr_info("x86: 'no_cet_shstk' specified, disabling Shadow Stack\n");
+ return 1;
+}
+__setup("no_cet_shstk", setup_disable_shstk);
+#endif
+
/*
* Some CPU features depend on higher CPUID levels, which may not always
* be available due to CPUID level capping or broken virtualization
@@ -1358,6 +1381,7 @@ static void identify_cpu(struct cpuinfo_x86 *c)
x86_init_rdrand(c);
x86_init_cache_qos(c);
setup_pku(c);
+ setup_cet(c);
/*
* Clear/Set all flags overridden by options, need do it
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 30ca2d1a9231..b3b0b482983a 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -39,6 +39,7 @@
#include <asm/desc.h>
#include <asm/prctl.h>
#include <asm/spec-ctrl.h>
+#include <asm/cet.h>
/*
* per-CPU TSS segments. Threads are completely 'soft' on Linux,
@@ -136,6 +137,7 @@ void flush_thread(void)
flush_ptrace_hw_breakpoint(tsk);
memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
+ cet_disable_shstk();
fpu__clear(&tsk->thread.fpu);
}
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index e9679016271f..a76739499e25 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -684,6 +684,9 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
[ilog2(VM_PKEY_BIT4)] = "",
#endif
#endif /* CONFIG_ARCH_HAS_PKEYS */
+#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER
+ [ilog2(VM_SHSTK)] = "ss"
+#endif
};
size_t i;
--
2.17.1
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