* Re: [PATCH v6 6/6] fs: introduce file_getattr and file_setattr syscalls
From: Christian Brauner @ 2025-07-03 8:28 UTC (permalink / raw)
To: Darrick J. Wong, Amir Goldstein, Jan Kara
Cc: Andrey Albershteyn, Arnd Bergmann, Casey Schaufler,
Pali Rohár, Paul Moore, linux-api, linux-fsdevel,
linux-kernel, linux-xfs, selinux, Andrey Albershteyn
In-Reply-To: <20250702183750.GW10009@frogsfrogsfrogs>
[-- Attachment #1: Type: text/plain, Size: 1945 bytes --]
On Wed, Jul 02, 2025 at 11:37:50AM -0700, Darrick J. Wong wrote:
> On Wed, Jul 02, 2025 at 03:43:28PM +0200, Amir Goldstein wrote:
> > On Wed, Jul 2, 2025 at 2:40 PM Christian Brauner <brauner@kernel.org> wrote:
> > >
> > > > Er... "fsx_fileattr" is the struct that the system call uses?
> > > >
> > > > That's a little confusing considering that xfs already has a
> > > > xfs_fill_fsxattr function that actually fills a struct fileattr.
> > > > That could be renamed xfs_fill_fileattr.
> > > >
> > > > I dunno. There's a part of me that would really rather that the
> > > > file_getattr and file_setattr syscalls operate on a struct file_attr.
> > >
> > > Agreed, I'm pretty sure I suggested this during an earlier review. Fits
> > > in line with struct mount_attr and others. Fwiw, struct fileattr (the
> > > kernel internal thing) should've really been struct file_kattr or struct
> > > kernel_file_attr. This is a common pattern now:
> > >
> > > struct mount_attr vs struct mount_kattr
> > >
> > > struct clone_args vs struct kernel_clone_kargs
> > >
> > > etc.
> > >file_attr
> >
> > I can see the allure, but we have a long history here with fsxattr,
> > so I think it serves the users better to reference this history with
> > fsxattr64.
>
> <shrug> XFS has a long history with 'struct fsxattr' (the structure you
> passed to XFS_IOC_FSGETXATTR) but the rest of the kernel needn't be so
> fixated upon the historical name. ext4/f2fs/overlay afaict are just
> going along for the ride.
>
> IOWs I like brauner's struct file_attr and struct file_kattr
> suggestions.
>
> > That, and also, avoid the churn of s/fileattr/file_kattr/
> > If you want to do this renaming, please do it in the same PR
> > because I don't like the idea of having both file_attr and fileattr
> > in the tree for an unknown period.
>
> But yeah, that ought to be a treewide change done at the same time.
Why do you all hate me? ;)
See the appended patch.
[-- Attachment #2: 0001-tree-wide-s-struct-fileattr-struct-file_kattr-g.patch --]
[-- Type: text/x-diff, Size: 45188 bytes --]
From 3a5f5c281e7993342cf285285fa0a496d4fca2b7 Mon Sep 17 00:00:00 2001
From: Christian Brauner <brauner@kernel.org>
Date: Thu, 3 Jul 2025 09:36:41 +0200
Subject: [PATCH] tree-wide: s/struct fileattr/struct file_kattr/g
Now that we expose struct file_attr as our uapi struct rename all the
internal struct to struct file_kattr to clearly communicate that it is a
kernel internal struct. This is similar to struct mount_{k}attr and
others.
Signed-off-by: Christian Brauner <brauner@kernel.org>
---
Documentation/filesystems/locking.rst | 4 ++--
Documentation/filesystems/vfs.rst | 4 ++--
fs/bcachefs/fs.c | 4 ++--
fs/btrfs/ioctl.c | 4 ++--
fs/btrfs/ioctl.h | 6 ++---
fs/ecryptfs/inode.c | 4 ++--
fs/efivarfs/inode.c | 4 ++--
fs/ext2/ext2.h | 4 ++--
fs/ext2/ioctl.c | 4 ++--
fs/ext4/ext4.h | 4 ++--
fs/ext4/ioctl.c | 4 ++--
fs/f2fs/f2fs.h | 4 ++--
fs/f2fs/file.c | 4 ++--
fs/file_attr.c | 34 +++++++++++++--------------
fs/fuse/fuse_i.h | 4 ++--
fs/fuse/ioctl.c | 4 ++--
fs/gfs2/file.c | 4 ++--
fs/gfs2/inode.h | 4 ++--
fs/hfsplus/hfsplus_fs.h | 4 ++--
fs/hfsplus/inode.c | 4 ++--
fs/jfs/ioctl.c | 4 ++--
fs/jfs/jfs_inode.h | 4 ++--
fs/nilfs2/ioctl.c | 4 ++--
fs/nilfs2/nilfs.h | 4 ++--
fs/ocfs2/ioctl.c | 4 ++--
fs/ocfs2/ioctl.h | 4 ++--
fs/orangefs/inode.c | 4 ++--
fs/overlayfs/copy_up.c | 4 ++--
fs/overlayfs/inode.c | 12 +++++-----
fs/overlayfs/overlayfs.h | 10 ++++----
fs/overlayfs/util.c | 2 +-
fs/ubifs/ioctl.c | 4 ++--
fs/ubifs/ubifs.h | 4 ++--
fs/xfs/xfs_ioctl.c | 18 +++++++-------
fs/xfs/xfs_ioctl.h | 4 ++--
include/linux/fileattr.h | 14 +++++------
include/linux/fs.h | 6 ++---
include/linux/lsm_hook_defs.h | 4 ++--
include/linux/security.h | 8 +++----
include/uapi/linux/fs.h | 2 +-
mm/shmem.c | 4 ++--
security/security.c | 4 ++--
security/selinux/hooks.c | 4 ++--
43 files changed, 122 insertions(+), 122 deletions(-)
diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst
index 2e567e341c3b..2ff02653d7cc 100644
--- a/Documentation/filesystems/locking.rst
+++ b/Documentation/filesystems/locking.rst
@@ -87,8 +87,8 @@ prototypes::
int (*tmpfile) (struct mnt_idmap *, struct inode *,
struct file *, umode_t);
int (*fileattr_set)(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
- int (*fileattr_get)(struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
+ int (*fileattr_get)(struct dentry *dentry, struct file_kattr *fa);
struct posix_acl * (*get_acl)(struct mnt_idmap *, struct dentry *, int);
struct offset_ctx *(*get_offset_ctx)(struct inode *inode);
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
index fd32a9a17bfb..f2bbf4def123 100644
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst
@@ -515,8 +515,8 @@ As of kernel 2.6.22, the following members are defined:
struct posix_acl * (*get_acl)(struct mnt_idmap *, struct dentry *, int);
int (*set_acl)(struct mnt_idmap *, struct dentry *, struct posix_acl *, int);
int (*fileattr_set)(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
- int (*fileattr_get)(struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
+ int (*fileattr_get)(struct dentry *dentry, struct file_kattr *fa);
struct offset_ctx *(*get_offset_ctx)(struct inode *inode);
};
diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c
index 85d13f800165..7c4de887629c 100644
--- a/fs/bcachefs/fs.c
+++ b/fs/bcachefs/fs.c
@@ -1619,7 +1619,7 @@ static const __maybe_unused unsigned bch_flags_to_xflags[] = {
};
static int bch2_fileattr_get(struct dentry *dentry,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
struct bch_inode_info *inode = to_bch_ei(d_inode(dentry));
struct bch_fs *c = inode->v.i_sb->s_fs_info;
@@ -1682,7 +1682,7 @@ static int fssetxattr_inode_update_fn(struct btree_trans *trans,
static int bch2_fileattr_set(struct mnt_idmap *idmap,
struct dentry *dentry,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
struct bch_inode_info *inode = to_bch_ei(d_inode(dentry));
struct bch_fs *c = inode->v.i_sb->s_fs_info;
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 913acef3f0a9..ffb28bfba4fa 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -245,7 +245,7 @@ static int btrfs_check_ioctl_vol_args2_subvol_name(const struct btrfs_ioctl_vol_
* Set flags/xflags from the internal inode flags. The remaining items of
* fsxattr are zeroed.
*/
-int btrfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int btrfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
const struct btrfs_inode *inode = BTRFS_I(d_inode(dentry));
@@ -254,7 +254,7 @@ int btrfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
}
int btrfs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct btrfs_inode *inode = BTRFS_I(d_inode(dentry));
struct btrfs_root *root = inode->root;
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index e08ea446cf48..ccf6bed9cc24 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -8,7 +8,7 @@
struct file;
struct dentry;
struct mnt_idmap;
-struct fileattr;
+struct file_kattr;
struct io_uring_cmd;
struct btrfs_inode;
struct btrfs_fs_info;
@@ -16,9 +16,9 @@ struct btrfs_ioctl_balance_args;
long btrfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
long btrfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
-int btrfs_fileattr_get(struct dentry *dentry, struct fileattr *fa);
+int btrfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
int btrfs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
int btrfs_ioctl_get_supported_features(void __user *arg);
void btrfs_sync_inode_flags_to_i_flags(struct btrfs_inode *inode);
void btrfs_update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 493d7f194956..d83416af17b4 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -1124,13 +1124,13 @@ static int ecryptfs_removexattr(struct dentry *dentry, struct inode *inode,
return rc;
}
-static int ecryptfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+static int ecryptfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
return vfs_fileattr_get(ecryptfs_dentry_to_lower(dentry), fa);
}
static int ecryptfs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
int rc;
diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c
index 98a7299a9ee9..2891614abf8d 100644
--- a/fs/efivarfs/inode.c
+++ b/fs/efivarfs/inode.c
@@ -138,7 +138,7 @@ const struct inode_operations efivarfs_dir_inode_operations = {
};
static int
-efivarfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+efivarfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
unsigned int i_flags;
unsigned int flags = 0;
@@ -154,7 +154,7 @@ efivarfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
static int
efivarfs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
unsigned int i_flags = 0;
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 4025f875252a..cf97b76e9fd3 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -750,9 +750,9 @@ extern int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
u64 start, u64 len);
/* ioctl.c */
-extern int ext2_fileattr_get(struct dentry *dentry, struct fileattr *fa);
+extern int ext2_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
extern int ext2_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
extern long ext2_ioctl(struct file *, unsigned int, unsigned long);
extern long ext2_compat_ioctl(struct file *, unsigned int, unsigned long);
diff --git a/fs/ext2/ioctl.c b/fs/ext2/ioctl.c
index 44e04484e570..c3fea55b8efa 100644
--- a/fs/ext2/ioctl.c
+++ b/fs/ext2/ioctl.c
@@ -18,7 +18,7 @@
#include <linux/uaccess.h>
#include <linux/fileattr.h>
-int ext2_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int ext2_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct ext2_inode_info *ei = EXT2_I(d_inode(dentry));
@@ -28,7 +28,7 @@ int ext2_fileattr_get(struct dentry *dentry, struct fileattr *fa)
}
int ext2_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct ext2_inode_info *ei = EXT2_I(inode);
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 18373de980f2..7d962e7f388a 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3103,8 +3103,8 @@ extern int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
extern long ext4_ioctl(struct file *, unsigned int, unsigned long);
extern long ext4_compat_ioctl(struct file *, unsigned int, unsigned long);
int ext4_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
-int ext4_fileattr_get(struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
+int ext4_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
extern void ext4_reset_inode_seed(struct inode *inode);
int ext4_update_overhead(struct super_block *sb, bool force);
int ext4_force_shutdown(struct super_block *sb, u32 flags);
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 5668a17458ae..84e3c73952d7 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -980,7 +980,7 @@ static long ext4_ioctl_group_add(struct file *file,
return err;
}
-int ext4_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int ext4_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct ext4_inode_info *ei = EXT4_I(inode);
@@ -997,7 +997,7 @@ int ext4_fileattr_get(struct dentry *dentry, struct fileattr *fa)
}
int ext4_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
u32 flags = fa->flags;
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 9333a22b9a01..c78464792ceb 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3615,9 +3615,9 @@ void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count);
int f2fs_do_shutdown(struct f2fs_sb_info *sbi, unsigned int flag,
bool readonly, bool need_lock);
int f2fs_precache_extents(struct inode *inode);
-int f2fs_fileattr_get(struct dentry *dentry, struct fileattr *fa);
+int f2fs_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
int f2fs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
int f2fs_transfer_project_quota(struct inode *inode, kprojid_t kprojid);
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 6bd3de64f2a8..90180ca22abd 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3356,7 +3356,7 @@ static int f2fs_ioc_setproject(struct inode *inode, __u32 projid)
}
#endif
-int f2fs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int f2fs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct f2fs_inode_info *fi = F2FS_I(inode);
@@ -3380,7 +3380,7 @@ int f2fs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
}
int f2fs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
u32 fsflags = fa->flags, mask = F2FS_SETTABLE_FS_FL;
diff --git a/fs/file_attr.c b/fs/file_attr.c
index 21d6a0607345..17745c89e2be 100644
--- a/fs/file_attr.c
+++ b/fs/file_attr.c
@@ -17,7 +17,7 @@
* Set ->fsx_xflags, ->fsx_valid and ->flags (translated xflags). All
* other fields are zeroed.
*/
-void fileattr_fill_xflags(struct fileattr *fa, u32 xflags)
+void fileattr_fill_xflags(struct file_kattr *fa, u32 xflags)
{
memset(fa, 0, sizeof(*fa));
fa->fsx_valid = true;
@@ -47,7 +47,7 @@ EXPORT_SYMBOL(fileattr_fill_xflags);
* Set ->flags, ->flags_valid and ->fsx_xflags (translated flags).
* All other fields are zeroed.
*/
-void fileattr_fill_flags(struct fileattr *fa, u32 flags)
+void fileattr_fill_flags(struct file_kattr *fa, u32 flags)
{
memset(fa, 0, sizeof(*fa));
fa->flags_valid = true;
@@ -78,7 +78,7 @@ EXPORT_SYMBOL(fileattr_fill_flags);
*
* Return: 0 on success, or a negative error on failure.
*/
-int vfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int vfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
int error;
@@ -94,7 +94,7 @@ int vfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
}
EXPORT_SYMBOL(vfs_fileattr_get);
-static void fileattr_to_file_attr(const struct fileattr *fa,
+static void fileattr_to_file_attr(const struct file_kattr *fa,
struct file_attr *fattr)
{
__u32 mask = FS_XFLAGS_MASK;
@@ -114,7 +114,7 @@ static void fileattr_to_file_attr(const struct fileattr *fa,
*
* Return: 0 on success, or -EFAULT on failure.
*/
-int copy_fsxattr_to_user(const struct fileattr *fa, struct fsxattr __user *ufa)
+int copy_fsxattr_to_user(const struct file_kattr *fa, struct fsxattr __user *ufa)
{
struct fsxattr xfa;
__u32 mask = FS_XFLAGS_MASK;
@@ -134,7 +134,7 @@ int copy_fsxattr_to_user(const struct fileattr *fa, struct fsxattr __user *ufa)
EXPORT_SYMBOL(copy_fsxattr_to_user);
static int file_attr_to_fileattr(const struct file_attr *fattr,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
__u32 mask = FS_XFLAGS_MASK;
@@ -150,7 +150,7 @@ static int file_attr_to_fileattr(const struct file_attr *fattr,
return 0;
}
-static int copy_fsxattr_from_user(struct fileattr *fa,
+static int copy_fsxattr_from_user(struct file_kattr *fa,
struct fsxattr __user *ufa)
{
struct fsxattr xfa;
@@ -179,8 +179,8 @@ static int copy_fsxattr_from_user(struct fileattr *fa,
* Note: must be called with inode lock held.
*/
static int fileattr_set_prepare(struct inode *inode,
- const struct fileattr *old_ma,
- struct fileattr *fa)
+ const struct file_kattr *old_ma,
+ struct file_kattr *fa)
{
int err;
@@ -263,10 +263,10 @@ static int fileattr_set_prepare(struct inode *inode,
* Return: 0 on success, or a negative error on failure.
*/
int vfs_fileattr_set(struct mnt_idmap *idmap, struct dentry *dentry,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
- struct fileattr old_ma = {};
+ struct file_kattr old_ma = {};
int err;
if (!inode->i_op->fileattr_set)
@@ -308,7 +308,7 @@ EXPORT_SYMBOL(vfs_fileattr_set);
int ioctl_getflags(struct file *file, unsigned int __user *argp)
{
- struct fileattr fa = { .flags_valid = true }; /* hint only */
+ struct file_kattr fa = { .flags_valid = true }; /* hint only */
int err;
err = vfs_fileattr_get(file->f_path.dentry, &fa);
@@ -324,7 +324,7 @@ int ioctl_setflags(struct file *file, unsigned int __user *argp)
{
struct mnt_idmap *idmap = file_mnt_idmap(file);
struct dentry *dentry = file->f_path.dentry;
- struct fileattr fa;
+ struct file_kattr fa;
unsigned int flags;
int err;
@@ -345,7 +345,7 @@ EXPORT_SYMBOL(ioctl_setflags);
int ioctl_fsgetxattr(struct file *file, void __user *argp)
{
- struct fileattr fa = { .fsx_valid = true }; /* hint only */
+ struct file_kattr fa = { .fsx_valid = true }; /* hint only */
int err;
err = vfs_fileattr_get(file->f_path.dentry, &fa);
@@ -362,7 +362,7 @@ int ioctl_fssetxattr(struct file *file, void __user *argp)
{
struct mnt_idmap *idmap = file_mnt_idmap(file);
struct dentry *dentry = file->f_path.dentry;
- struct fileattr fa;
+ struct file_kattr fa;
int err;
err = copy_fsxattr_from_user(&fa, argp);
@@ -387,7 +387,7 @@ SYSCALL_DEFINE5(file_getattr, int, dfd, const char __user *, filename,
struct filename *name __free(putname) = NULL;
unsigned int lookup_flags = 0;
struct file_attr fattr;
- struct fileattr fa;
+ struct file_kattr fa;
int error;
BUILD_BUG_ON(sizeof(struct file_attr) < FILE_ATTR_SIZE_VER0);
@@ -442,7 +442,7 @@ SYSCALL_DEFINE5(file_setattr, int, dfd, const char __user *, filename,
struct filename *name __free(putname) = NULL;
unsigned int lookup_flags = 0;
struct file_attr fattr;
- struct fileattr fa;
+ struct file_kattr fa;
int error;
BUILD_BUG_ON(sizeof(struct file_attr) < FILE_ATTR_SIZE_VER0);
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index b54f4f57789f..501f64ceeab3 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1486,9 +1486,9 @@ void fuse_dax_cancel_work(struct fuse_conn *fc);
long fuse_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg);
-int fuse_fileattr_get(struct dentry *dentry, struct fileattr *fa);
+int fuse_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
int fuse_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
/* iomode.c */
int fuse_file_cached_io_open(struct inode *inode, struct fuse_file *ff);
diff --git a/fs/fuse/ioctl.c b/fs/fuse/ioctl.c
index f2692f7d5932..57032eadca6c 100644
--- a/fs/fuse/ioctl.c
+++ b/fs/fuse/ioctl.c
@@ -502,7 +502,7 @@ static void fuse_priv_ioctl_cleanup(struct inode *inode, struct fuse_file *ff)
fuse_file_release(inode, ff, O_RDONLY, NULL, S_ISDIR(inode->i_mode));
}
-int fuse_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int fuse_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct fuse_file *ff;
@@ -542,7 +542,7 @@ int fuse_fileattr_get(struct dentry *dentry, struct fileattr *fa)
}
int fuse_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct fuse_file *ff;
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index fd1147aa3891..65f4371f428c 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -155,7 +155,7 @@ static inline u32 gfs2_gfsflags_to_fsflags(struct inode *inode, u32 gfsflags)
return fsflags;
}
-int gfs2_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int gfs2_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct gfs2_inode *ip = GFS2_I(inode);
@@ -276,7 +276,7 @@ static int do_gfs2_set_flags(struct inode *inode, u32 reqflags, u32 mask)
}
int gfs2_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
u32 fsflags = fa->flags, gfsflags = 0;
diff --git a/fs/gfs2/inode.h b/fs/gfs2/inode.h
index eafe123617e6..dd970e644fe0 100644
--- a/fs/gfs2/inode.h
+++ b/fs/gfs2/inode.h
@@ -107,9 +107,9 @@ loff_t gfs2_seek_hole(struct file *file, loff_t offset);
extern const struct file_operations gfs2_file_fops_nolock;
extern const struct file_operations gfs2_dir_fops_nolock;
-int gfs2_fileattr_get(struct dentry *dentry, struct fileattr *fa);
+int gfs2_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
int gfs2_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
void gfs2_set_inode_flags(struct inode *inode);
#ifdef CONFIG_GFS2_FS_LOCKING_DLM
diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index 2f089bff0095..927db2b8b17c 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -489,9 +489,9 @@ int hfsplus_getattr(struct mnt_idmap *idmap, const struct path *path,
unsigned int query_flags);
int hfsplus_file_fsync(struct file *file, loff_t start, loff_t end,
int datasync);
-int hfsplus_fileattr_get(struct dentry *dentry, struct fileattr *fa);
+int hfsplus_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
int hfsplus_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
/* ioctl.c */
long hfsplus_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
diff --git a/fs/hfsplus/inode.c b/fs/hfsplus/inode.c
index f331e9574217..3ec0b33808c0 100644
--- a/fs/hfsplus/inode.c
+++ b/fs/hfsplus/inode.c
@@ -654,7 +654,7 @@ int hfsplus_cat_write_inode(struct inode *inode)
return res;
}
-int hfsplus_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int hfsplus_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
@@ -673,7 +673,7 @@ int hfsplus_fileattr_get(struct dentry *dentry, struct fileattr *fa)
}
int hfsplus_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
diff --git a/fs/jfs/ioctl.c b/fs/jfs/ioctl.c
index f7bd7e8f5be4..563f148be8af 100644
--- a/fs/jfs/ioctl.c
+++ b/fs/jfs/ioctl.c
@@ -57,7 +57,7 @@ static long jfs_map_ext2(unsigned long flags, int from)
return mapped;
}
-int jfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int jfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct jfs_inode_info *jfs_inode = JFS_IP(d_inode(dentry));
unsigned int flags = jfs_inode->mode2 & JFS_FL_USER_VISIBLE;
@@ -71,7 +71,7 @@ int jfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
}
int jfs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct jfs_inode_info *jfs_inode = JFS_IP(inode);
diff --git a/fs/jfs/jfs_inode.h b/fs/jfs/jfs_inode.h
index ea80661597ac..2c6c81c8cb9f 100644
--- a/fs/jfs/jfs_inode.h
+++ b/fs/jfs/jfs_inode.h
@@ -9,9 +9,9 @@ struct fid;
extern struct inode *ialloc(struct inode *, umode_t);
extern int jfs_fsync(struct file *, loff_t, loff_t, int);
-extern int jfs_fileattr_get(struct dentry *dentry, struct fileattr *fa);
+extern int jfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
extern int jfs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
extern long jfs_ioctl(struct file *, unsigned int, unsigned long);
extern struct inode *jfs_iget(struct super_block *, unsigned long);
extern int jfs_commit_inode(struct inode *, int);
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index a66d62a51f77..3288c3b4be9e 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -118,7 +118,7 @@ static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
*
* Return: always 0 as success.
*/
-int nilfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int nilfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
@@ -136,7 +136,7 @@ int nilfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
* Return: 0 on success, or a negative error code on failure.
*/
int nilfs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct nilfs_transaction_info ti;
diff --git a/fs/nilfs2/nilfs.h b/fs/nilfs2/nilfs.h
index cb6ed54accd7..f466daa39440 100644
--- a/fs/nilfs2/nilfs.h
+++ b/fs/nilfs2/nilfs.h
@@ -268,9 +268,9 @@ int nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
extern int nilfs_sync_file(struct file *, loff_t, loff_t, int);
/* ioctl.c */
-int nilfs_fileattr_get(struct dentry *dentry, struct fileattr *m);
+int nilfs_fileattr_get(struct dentry *dentry, struct file_kattr *m);
int nilfs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
long nilfs_ioctl(struct file *, unsigned int, unsigned long);
long nilfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *, struct nilfs_argv *,
diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
index 7ae96fb8807a..db14c92302a1 100644
--- a/fs/ocfs2/ioctl.c
+++ b/fs/ocfs2/ioctl.c
@@ -62,7 +62,7 @@ static inline int o2info_coherent(struct ocfs2_info_request *req)
return (!(req->ir_flags & OCFS2_INFO_FL_NON_COHERENT));
}
-int ocfs2_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int ocfs2_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
unsigned int flags;
@@ -83,7 +83,7 @@ int ocfs2_fileattr_get(struct dentry *dentry, struct fileattr *fa)
}
int ocfs2_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
unsigned int flags = fa->flags;
diff --git a/fs/ocfs2/ioctl.h b/fs/ocfs2/ioctl.h
index 48a5fdfe87a1..4a1c2313b429 100644
--- a/fs/ocfs2/ioctl.h
+++ b/fs/ocfs2/ioctl.h
@@ -11,9 +11,9 @@
#ifndef OCFS2_IOCTL_PROTO_H
#define OCFS2_IOCTL_PROTO_H
-int ocfs2_fileattr_get(struct dentry *dentry, struct fileattr *fa);
+int ocfs2_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
int ocfs2_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
long ocfs2_compat_ioctl(struct file *file, unsigned cmd, unsigned long arg);
diff --git a/fs/orangefs/inode.c b/fs/orangefs/inode.c
index 08a6f372a352..926d1659902d 100644
--- a/fs/orangefs/inode.c
+++ b/fs/orangefs/inode.c
@@ -887,7 +887,7 @@ int orangefs_update_time(struct inode *inode, int flags)
return __orangefs_setattr(inode, &iattr);
}
-static int orangefs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+static int orangefs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
u64 val = 0;
int ret;
@@ -908,7 +908,7 @@ static int orangefs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
}
static int orangefs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
u64 val = 0;
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 2c646b7076d0..74817e1ece19 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -171,8 +171,8 @@ int ovl_copy_xattr(struct super_block *sb, const struct path *oldpath, struct de
static int ovl_copy_fileattr(struct inode *inode, const struct path *old,
const struct path *new)
{
- struct fileattr oldfa = { .flags_valid = true };
- struct fileattr newfa = { .flags_valid = true };
+ struct file_kattr oldfa = { .flags_valid = true };
+ struct file_kattr newfa = { .flags_valid = true };
int err;
err = ovl_real_fileattr_get(old, &oldfa);
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index cf3581dc1034..ecb9f2019395 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -610,7 +610,7 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
* Introducing security_inode_fileattr_get/set() hooks would solve this issue
* properly.
*/
-static int ovl_security_fileattr(const struct path *realpath, struct fileattr *fa,
+static int ovl_security_fileattr(const struct path *realpath, struct file_kattr *fa,
bool set)
{
struct file *file;
@@ -637,7 +637,7 @@ static int ovl_security_fileattr(const struct path *realpath, struct fileattr *f
return err;
}
-int ovl_real_fileattr_set(const struct path *realpath, struct fileattr *fa)
+int ovl_real_fileattr_set(const struct path *realpath, struct file_kattr *fa)
{
int err;
@@ -649,7 +649,7 @@ int ovl_real_fileattr_set(const struct path *realpath, struct fileattr *fa)
}
int ovl_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct path upperpath;
@@ -697,7 +697,7 @@ int ovl_fileattr_set(struct mnt_idmap *idmap,
}
/* Convert inode protection flags to fileattr flags */
-static void ovl_fileattr_prot_flags(struct inode *inode, struct fileattr *fa)
+static void ovl_fileattr_prot_flags(struct inode *inode, struct file_kattr *fa)
{
BUILD_BUG_ON(OVL_PROT_FS_FLAGS_MASK & ~FS_COMMON_FL);
BUILD_BUG_ON(OVL_PROT_FSX_FLAGS_MASK & ~FS_XFLAG_COMMON);
@@ -712,7 +712,7 @@ static void ovl_fileattr_prot_flags(struct inode *inode, struct fileattr *fa)
}
}
-int ovl_real_fileattr_get(const struct path *realpath, struct fileattr *fa)
+int ovl_real_fileattr_get(const struct path *realpath, struct file_kattr *fa)
{
int err;
@@ -723,7 +723,7 @@ int ovl_real_fileattr_get(const struct path *realpath, struct fileattr *fa)
return vfs_fileattr_get(realpath->dentry, fa);
}
-int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int ovl_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct path realpath;
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 8baaba0a3fe5..e19d91f22186 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -815,7 +815,7 @@ void ovl_copyattr(struct inode *to);
void ovl_check_protattr(struct inode *inode, struct dentry *upper);
int ovl_set_protattr(struct inode *inode, struct dentry *upper,
- struct fileattr *fa);
+ struct file_kattr *fa);
static inline void ovl_copyflags(struct inode *from, struct inode *to)
{
@@ -847,11 +847,11 @@ struct dentry *ovl_create_temp(struct ovl_fs *ofs, struct dentry *workdir,
/* file.c */
extern const struct file_operations ovl_file_operations;
-int ovl_real_fileattr_get(const struct path *realpath, struct fileattr *fa);
-int ovl_real_fileattr_set(const struct path *realpath, struct fileattr *fa);
-int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa);
+int ovl_real_fileattr_get(const struct path *realpath, struct file_kattr *fa);
+int ovl_real_fileattr_set(const struct path *realpath, struct file_kattr *fa);
+int ovl_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
int ovl_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
struct ovl_file;
struct ovl_file *ovl_file_alloc(struct file *realfile);
void ovl_file_free(struct ovl_file *of);
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index dcccb4b4a66c..607860f199a8 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -959,7 +959,7 @@ void ovl_check_protattr(struct inode *inode, struct dentry *upper)
}
int ovl_set_protattr(struct inode *inode, struct dentry *upper,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
struct ovl_fs *ofs = OVL_FS(inode->i_sb);
char buf[OVL_PROTATTR_MAX];
diff --git a/fs/ubifs/ioctl.c b/fs/ubifs/ioctl.c
index 2c99349cf537..79536b2e3d7a 100644
--- a/fs/ubifs/ioctl.c
+++ b/fs/ubifs/ioctl.c
@@ -130,7 +130,7 @@ static int setflags(struct inode *inode, int flags)
return err;
}
-int ubifs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+int ubifs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
int flags = ubifs2ioctl(ubifs_inode(inode)->flags);
@@ -145,7 +145,7 @@ int ubifs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
}
int ubifs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
int flags = fa->flags;
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 256dbaeeb0de..5db45c9e26ee 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -2073,9 +2073,9 @@ int ubifs_recover_size(struct ubifs_info *c, bool in_place);
void ubifs_destroy_size_tree(struct ubifs_info *c);
/* ioctl.c */
-int ubifs_fileattr_get(struct dentry *dentry, struct fileattr *fa);
+int ubifs_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
int ubifs_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
long ubifs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
void ubifs_set_inode_flags(struct inode *inode);
#ifdef CONFIG_COMPAT
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index d250f7f74e3b..6d573e736a67 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -444,7 +444,7 @@ static void
xfs_fill_fsxattr(
struct xfs_inode *ip,
int whichfork,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);
@@ -496,7 +496,7 @@ xfs_ioc_fsgetxattra(
xfs_inode_t *ip,
void __user *arg)
{
- struct fileattr fa;
+ struct file_kattr fa;
xfs_ilock(ip, XFS_ILOCK_SHARED);
xfs_fill_fsxattr(ip, XFS_ATTR_FORK, &fa);
@@ -508,7 +508,7 @@ xfs_ioc_fsgetxattra(
int
xfs_fileattr_get(
struct dentry *dentry,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
struct xfs_inode *ip = XFS_I(d_inode(dentry));
@@ -526,7 +526,7 @@ static int
xfs_ioctl_setattr_xflags(
struct xfs_trans *tp,
struct xfs_inode *ip,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
struct xfs_mount *mp = ip->i_mount;
bool rtflag = (fa->fsx_xflags & FS_XFLAG_REALTIME);
@@ -582,7 +582,7 @@ xfs_ioctl_setattr_xflags(
static void
xfs_ioctl_setattr_prepare_dax(
struct xfs_inode *ip,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
struct xfs_mount *mp = ip->i_mount;
struct inode *inode = VFS_I(ip);
@@ -642,7 +642,7 @@ xfs_ioctl_setattr_get_trans(
static int
xfs_ioctl_setattr_check_extsize(
struct xfs_inode *ip,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
struct xfs_mount *mp = ip->i_mount;
xfs_failaddr_t failaddr;
@@ -684,7 +684,7 @@ xfs_ioctl_setattr_check_extsize(
static int
xfs_ioctl_setattr_check_cowextsize(
struct xfs_inode *ip,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
struct xfs_mount *mp = ip->i_mount;
xfs_failaddr_t failaddr;
@@ -709,7 +709,7 @@ xfs_ioctl_setattr_check_cowextsize(
static int
xfs_ioctl_setattr_check_projid(
struct xfs_inode *ip,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
if (!fa->fsx_valid)
return 0;
@@ -725,7 +725,7 @@ int
xfs_fileattr_set(
struct mnt_idmap *idmap,
struct dentry *dentry,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
struct xfs_inode *ip = XFS_I(d_inode(dentry));
struct xfs_mount *mp = ip->i_mount;
diff --git a/fs/xfs/xfs_ioctl.h b/fs/xfs/xfs_ioctl.h
index 12124946f347..f5a831e9de4a 100644
--- a/fs/xfs/xfs_ioctl.h
+++ b/fs/xfs/xfs_ioctl.h
@@ -17,13 +17,13 @@ xfs_ioc_swapext(
extern int
xfs_fileattr_get(
struct dentry *dentry,
- struct fileattr *fa);
+ struct file_kattr *fa);
extern int
xfs_fileattr_set(
struct mnt_idmap *idmap,
struct dentry *dentry,
- struct fileattr *fa);
+ struct file_kattr *fa);
extern long
xfs_file_ioctl(
diff --git a/include/linux/fileattr.h b/include/linux/fileattr.h
index e2a2f4ae242d..f89dcfad3f8f 100644
--- a/include/linux/fileattr.h
+++ b/include/linux/fileattr.h
@@ -40,7 +40,7 @@
* is handled by the VFS helpers, so filesystems are free to implement just one
* or both of these sub-interfaces.
*/
-struct fileattr {
+struct file_kattr {
u32 flags; /* flags (FS_IOC_GETFLAGS/FS_IOC_SETFLAGS) */
/* struct fsxattr: */
u32 fsx_xflags; /* xflags field value (get/set) */
@@ -53,10 +53,10 @@ struct fileattr {
bool fsx_valid:1;
};
-int copy_fsxattr_to_user(const struct fileattr *fa, struct fsxattr __user *ufa);
+int copy_fsxattr_to_user(const struct file_kattr *fa, struct fsxattr __user *ufa);
-void fileattr_fill_xflags(struct fileattr *fa, u32 xflags);
-void fileattr_fill_flags(struct fileattr *fa, u32 flags);
+void fileattr_fill_xflags(struct file_kattr *fa, u32 xflags);
+void fileattr_fill_flags(struct file_kattr *fa, u32 flags);
/**
* fileattr_has_fsx - check for extended flags/attributes
@@ -65,16 +65,16 @@ void fileattr_fill_flags(struct fileattr *fa, u32 flags);
* Return: true if any attributes are present that are not represented in
* ->flags.
*/
-static inline bool fileattr_has_fsx(const struct fileattr *fa)
+static inline bool fileattr_has_fsx(const struct file_kattr *fa)
{
return fa->fsx_valid &&
((fa->fsx_xflags & ~FS_XFLAG_COMMON) || fa->fsx_extsize != 0 ||
fa->fsx_projid != 0 || fa->fsx_cowextsize != 0);
}
-int vfs_fileattr_get(struct dentry *dentry, struct fileattr *fa);
+int vfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
int vfs_fileattr_set(struct mnt_idmap *idmap, struct dentry *dentry,
- struct fileattr *fa);
+ struct file_kattr *fa);
int ioctl_getflags(struct file *file, unsigned int __user *argp);
int ioctl_setflags(struct file *file, unsigned int __user *argp);
int ioctl_fsgetxattr(struct file *file, void __user *argp);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 96c7925a6551..0c58617645ea 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -80,7 +80,7 @@ struct fsnotify_mark_connector;
struct fsnotify_sb_info;
struct fs_context;
struct fs_parameter_spec;
-struct fileattr;
+struct file_kattr;
struct iomap_ops;
extern void __init inode_init(void);
@@ -2254,8 +2254,8 @@ struct inode_operations {
int (*set_acl)(struct mnt_idmap *, struct dentry *,
struct posix_acl *, int);
int (*fileattr_set)(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa);
- int (*fileattr_get)(struct dentry *dentry, struct fileattr *fa);
+ struct dentry *dentry, struct file_kattr *fa);
+ int (*fileattr_get)(struct dentry *dentry, struct file_kattr *fa);
struct offset_ctx *(*get_offset_ctx)(struct inode *inode);
} ____cacheline_aligned;
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 9600a4350e79..fd11fffdd3c3 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -157,8 +157,8 @@ LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
struct dentry *dentry, const char *name)
LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry,
const char *name)
-LSM_HOOK(int, 0, inode_file_setattr, struct dentry *dentry, struct fileattr *fa)
-LSM_HOOK(int, 0, inode_file_getattr, struct dentry *dentry, struct fileattr *fa)
+LSM_HOOK(int, 0, inode_file_setattr, struct dentry *dentry, struct file_kattr *fa)
+LSM_HOOK(int, 0, inode_file_getattr, struct dentry *dentry, struct file_kattr *fa)
LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap,
struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
LSM_HOOK(void, LSM_RET_VOID, inode_post_set_acl, struct dentry *dentry,
diff --git a/include/linux/security.h b/include/linux/security.h
index 9ed0d0e0c81f..b95b5540c429 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -452,9 +452,9 @@ int security_inode_removexattr(struct mnt_idmap *idmap,
struct dentry *dentry, const char *name);
void security_inode_post_removexattr(struct dentry *dentry, const char *name);
int security_inode_file_setattr(struct dentry *dentry,
- struct fileattr *fa);
+ struct file_kattr *fa);
int security_inode_file_getattr(struct dentry *dentry,
- struct fileattr *fa);
+ struct file_kattr *fa);
int security_inode_need_killpriv(struct dentry *dentry);
int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry);
int security_inode_getsecurity(struct mnt_idmap *idmap,
@@ -1057,13 +1057,13 @@ static inline void security_inode_post_removexattr(struct dentry *dentry,
{ }
static inline int security_inode_file_setattr(struct dentry *dentry,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
return 0;
}
static inline int security_inode_file_getattr(struct dentry *dentry,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
return 0;
}
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 9663dbdda181..6e136c9c6a22 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -151,7 +151,7 @@ struct fsxattr {
/*
* Variable size structure for file_[sg]et_attr().
*
- * Note. This is alternative to the structure 'struct fileattr'/'struct fsxattr'.
+ * Note. This is alternative to the structure 'struct file_kattr'/'struct fsxattr'.
* As this structure is passed to/from userspace with its size, this can
* be versioned based on the size.
*/
diff --git a/mm/shmem.c b/mm/shmem.c
index 0c5fb4ffa03a..6311fe35c577 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -4183,7 +4183,7 @@ static const char *shmem_get_link(struct dentry *dentry, struct inode *inode,
#ifdef CONFIG_TMPFS_XATTR
-static int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+static int shmem_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
@@ -4193,7 +4193,7 @@ static int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
}
static int shmem_fileattr_set(struct mnt_idmap *idmap,
- struct dentry *dentry, struct fileattr *fa)
+ struct dentry *dentry, struct file_kattr *fa)
{
struct inode *inode = d_inode(dentry);
struct shmem_inode_info *info = SHMEM_I(inode);
diff --git a/security/security.c b/security/security.c
index 711b4de40b8d..a5766cbf6f7c 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2632,7 +2632,7 @@ void security_inode_post_removexattr(struct dentry *dentry, const char *name)
*
* Return: Returns 0 if permission is granted.
*/
-int security_inode_file_setattr(struct dentry *dentry, struct fileattr *fa)
+int security_inode_file_setattr(struct dentry *dentry, struct file_kattr *fa)
{
return call_int_hook(inode_file_setattr, dentry, fa);
}
@@ -2647,7 +2647,7 @@ int security_inode_file_setattr(struct dentry *dentry, struct fileattr *fa)
*
* Return: Returns 0 if permission is granted.
*/
-int security_inode_file_getattr(struct dentry *dentry, struct fileattr *fa)
+int security_inode_file_getattr(struct dentry *dentry, struct file_kattr *fa)
{
return call_int_hook(inode_file_getattr, dentry, fa);
}
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index be7aca2269fa..0dadce2267c1 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3481,13 +3481,13 @@ static int selinux_inode_removexattr(struct mnt_idmap *idmap,
}
static int selinux_inode_file_setattr(struct dentry *dentry,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
return dentry_has_perm(current_cred(), dentry, FILE__SETATTR);
}
static int selinux_inode_file_getattr(struct dentry *dentry,
- struct fileattr *fa)
+ struct file_kattr *fa)
{
return dentry_has_perm(current_cred(), dentry, FILE__GETATTR);
}
--
2.47.2
^ permalink raw reply related
* Re: [PATCH v6 6/6] fs: introduce file_getattr and file_setattr syscalls
From: Darrick J. Wong @ 2025-07-02 18:37 UTC (permalink / raw)
To: Amir Goldstein
Cc: Christian Brauner, Andrey Albershteyn, Arnd Bergmann,
Casey Schaufler, Jan Kara, Pali Rohár, Paul Moore, linux-api,
linux-fsdevel, linux-kernel, linux-xfs, selinux,
Andrey Albershteyn
In-Reply-To: <CAOQ4uximwjYabeO=-ktMtnzMsx6KXBs=pUsgNno=_qgpQnpHCA@mail.gmail.com>
On Wed, Jul 02, 2025 at 03:43:28PM +0200, Amir Goldstein wrote:
> On Wed, Jul 2, 2025 at 2:40 PM Christian Brauner <brauner@kernel.org> wrote:
> >
> > > Er... "fsx_fileattr" is the struct that the system call uses?
> > >
> > > That's a little confusing considering that xfs already has a
> > > xfs_fill_fsxattr function that actually fills a struct fileattr.
> > > That could be renamed xfs_fill_fileattr.
> > >
> > > I dunno. There's a part of me that would really rather that the
> > > file_getattr and file_setattr syscalls operate on a struct file_attr.
> >
> > Agreed, I'm pretty sure I suggested this during an earlier review. Fits
> > in line with struct mount_attr and others. Fwiw, struct fileattr (the
> > kernel internal thing) should've really been struct file_kattr or struct
> > kernel_file_attr. This is a common pattern now:
> >
> > struct mount_attr vs struct mount_kattr
> >
> > struct clone_args vs struct kernel_clone_kargs
> >
> > etc.
> >file_attr
>
> I can see the allure, but we have a long history here with fsxattr,
> so I think it serves the users better to reference this history with
> fsxattr64.
<shrug> XFS has a long history with 'struct fsxattr' (the structure you
passed to XFS_IOC_FSGETXATTR) but the rest of the kernel needn't be so
fixated upon the historical name. ext4/f2fs/overlay afaict are just
going along for the ride.
IOWs I like brauner's struct file_attr and struct file_kattr
suggestions.
> That, and also, avoid the churn of s/fileattr/file_kattr/
> If you want to do this renaming, please do it in the same PR
> because I don't like the idea of having both file_attr and fileattr
> in the tree for an unknown period.
But yeah, that ought to be a treewide change done at the same time.
--D
>
> Thanks,
> Amir.
>
^ permalink raw reply
* Re: [DISCUSSION] proposed mctl() API
From: SeongJae Park @ 2025-07-02 17:38 UTC (permalink / raw)
To: Usama Arif
Cc: SeongJae Park, David Hildenbrand, linux-mm, Andrew Morton,
Shakeel Butt, Liam R . Howlett, Vlastimil Babka, Jann Horn,
Arnd Bergmann, Christian Brauner, Mike Rapoport, Johannes Weiner,
Barry Song, linux-arch, linux-kernel, linux-api, Pedro Falcato,
Matthew Wilcox, Lorenzo Stoakes
In-Reply-To: <6d8832bb-b5a7-4cd9-b92c-c93f2c1fe182@gmail.com>
On Wed, 2 Jul 2025 15:15:01 +0100 Usama Arif <usamaarif642@gmail.com> wrote:
[...]
> In terms of the approach of doing this, IMHO, I dont think the way to do this
> is controversial. After the great feedback from Lorenzo on the prctl series, the
> approach would be for userpsace to make a call that just does for_each_vma of the process,
> madvises the VMAs,
One dirty hack that I can think off the top of my head for doing this without
new kernel changes is, unsurprisingly, using DAMOS. Using DAMOS, users can do
madvise(MADV_HUGEPAGE) to virtual address ranges of specific access patterns.
It is aimed to be used for hot regions, while using similar one of
MADV_NOHUGEPAGE for cold regions. An experiment with a prototype[1] showed it
eliminates about 80% of internal fragmentation caused memory overhead while
keeping 46% of performance improvement under a constrained situation.
If you set the access pattern as any pattern, hence, you can do
madvise(MADV_HUGEPAGE) for effectively entire virtual address space of the
process. DAMON user-space tool supports periodically tracking childs and
applying same DAMOS scheme to those. So, for example, below hack could be
tried.
# damo start $(pidof XXX) --damos_action hugepage --include_child_tasks
I'm working with Usama at Meta but not very closely involved in THP works, so
I'm not sure if this works for Usama's case and others. I even not tried this
at all on any test environment. So I'm not recommending this but just sharing
a thought for more brainsorming, and that's why I call this a dirty hack.
[1] https://assets.amazon.science/b7/2b/ce53222247739b174f2b54498d1a/daos-data-access-aware-operating-system.pdf
Thanks,
SJ
[...]
^ permalink raw reply
* Re: [PATCH v18 4/8] fork: Add shadow stack support to clone3()
From: Yury Khrustalev @ 2025-07-02 14:52 UTC (permalink / raw)
To: Mark Brown
Cc: Rick P. Edgecombe, Deepak Gupta, Szabolcs Nagy, H.J. Lu,
Florian Weimer, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Dave Hansen, x86, H. Peter Anvin, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Valentin Schneider, Christian Brauner, Shuah Khan,
linux-kernel, Catalin Marinas, Will Deacon, jannh, Andrew Morton,
Wilco Dijkstra, linux-kselftest, linux-api, Kees Cook
In-Reply-To: <20250702-clone3-shadow-stack-v18-4-7965d2b694db@kernel.org>
On Wed, Jul 02, 2025 at 11:39:09AM +0100, Mark Brown wrote:
> Unlike with the normal stack there is no API for configuring the shadow
> stack for a new thread, instead the kernel will dynamically allocate a
> new shadow stack with the same size as the normal stack. This appears to
> be due to the shadow stack series having been in development since
> before the more extensible clone3() was added rather than anything more
> deliberate.
>
> Add a parameter to clone3() specifying a shadow stack pointer to use
> for the new thread, this is inconsistent with the way we specify the
> normal stack but during review concerns were expressed about having to
> identify where the shadow stack pointer should be placed especially in
> cases where the shadow stack has been previously active. If no shadow
> stack is specified then the existing implicit allocation behaviour is
> maintained.
>
> If a shadow stack pointer is specified then it is required to have an
> architecture defined token placed on the stack, this will be consumed by
> the new task, the shadow stack is specified by pointing to this token. If
> no valid token is present then this will be reported with -EINVAL. This
> token prevents new threads being created pointing at the shadow stack of
> an existing running thread. On architectures with support for userspace
> pivoting of shadow stacks it is expected that the same format and placement
> of tokens will be used, this is the case for arm64 and x86.
>
> If the architecture does not support shadow stacks the shadow stack
> pointer must be not be specified, architectures that do support the
> feature are expected to enforce the same requirement on individual
> systems that lack shadow stack support.
>
> Update the existing arm64 and x86 implementations to pay attention to
> the newly added arguments, in order to maintain compatibility we use the
> existing behaviour if no shadow stack is specified. Since we are now
> using more fields from the kernel_clone_args we pass that into the
> shadow stack code rather than individual fields.
>
> Portions of the x86 architecture code were written by Rick Edgecombe.
>
> Acked-by: Yury Khrustalev <yury.khrustalev@arm.com>
> Signed-off-by: Mark Brown <broonie@kernel.org>
Tested on a fast model with a WIP Glibc patch that uses extended version
of struct clone_args. No issues found, Glibc tests pass.
I used dummy syscall to detect support for shadow stack token in struct
clone_args.
Tested-by: Yury Khrustalev <yury.khrustalev@arm.com>
Kind regards,
Yury
^ permalink raw reply
* Re: [DISCUSSION] proposed mctl() API
From: Usama Arif @ 2025-07-02 14:15 UTC (permalink / raw)
To: David Hildenbrand, linux-mm, Andrew Morton
Cc: Shakeel Butt, Liam R . Howlett, Vlastimil Babka, Jann Horn,
Arnd Bergmann, Christian Brauner, SeongJae Park, Mike Rapoport,
Johannes Weiner, Barry Song, linux-arch, linux-kernel, linux-api,
Pedro Falcato, Matthew Wilcox, Lorenzo Stoakes
In-Reply-To: <2fd7f80c-2b13-4478-900a-d65547586db3@gmail.com>
> As I replied to Matthew in [1], it would be amazing if it was not needed, but thats not
> how it works in the medium term and I dont think it will work even in the long term.
> I will paste my answer from [1] below as well:
>
> If we have 2 workloads on the same server, For e.g. one is database where THPs
> just dont do well, but the other one is AI where THPs do really well. How
> will the kernel monitor that the database workload is performing worse
> and the AI one isnt?
>
> I added THP shrinker to hopefully try and do this automatically, and it does
> really help. But unfortunately it is not a complete solution.
> There are severely memory bound workloads where even a tiny increase
> in memory will lead to an OOM. And if you colocate the container thats running
> that workload with one in which we will benefit with THPs, we unfortunately
> can't just rely on the system doing the right thing.
>
> It would be awesome if THPs are truly transparent and don't require
> any input, but unfortunately I don't think that there is a solution
> for this with just kernel monitoring.
>
> This is just a big hint from the user. If the global system policy is madvise
> and the workload owner has done their own benchmarks and see benefits
> with always, they set DEFAULT_MADV_HUGEPAGE for the process to optin as "always".
> If the global system policy is always and the workload owner has done their own
> benchmarks and see worse results with always, they set DEFAULT_MADV_NOHUGEPAGE for
> the process to optin as "madvise".
>
> [1] https://lore.kernel.org/all/162c14e6-0b16-4698-bd76-735037ea0d73@gmail.com/
>
>
> I havent seen activity on this thread over the past week, but I was hoping
> we can reach a consensus on which approach to use, prctl or mctl.
> If its mctl and if you don't think this should be done, please let me know
> if you would like me to work on this instead. This is a valid big realworld
> usecase that is a real blocker for deploying THPs in workloads in servers.
>
Hi!
Just wanted to check if anyone has any thoughts on this?
I think we are all in agreement for the long term eventual goal, have THP just work
and be default enabled. From our perspective, we (meta) have spent a significant
amount of time and effort over the last 18 months trying to make changes/optimizations
where we could actually have it so and can transparently and reliably get hugepages.
This includes the THP shrinker [1], changes to allocator and reclaim/compaction code
to reduce fragmentation [2] and reducing type mixing [3].
We want to continue spending more time and resources in trying to achieve this.
But in the current state, not being able to selectively enable THPs always for certain
workloads is a significant blocker in trying to roll it out at hyperscaler levels, and
from the attempts made by others, I do believe its a problem others are facing as well.
Our long term aim is to have transparent_hugepage/enabled set to always across the fleet.
But for that we need to have the ability to enable it selectively for workloads that
show benefit, try and solve problems that come up in production when it is enabled,
and see why for those that regress. This can not be done with just transparent_hugepage/enabled
for hyperscalers which run vastly different types of containerized workloads on the same
machine.
There have been multiple efforts from different people on trying to address similar
problems (including via cgroup[4] and bpf[5]). IMHO, its quite clear that unfortunately
just having a system wide setting for THP is not enough at the moment or in the near future,
especially when running workloads that have completely different characteristic on the same server.
In terms of the approach of doing this, IMHO, I dont think the way to do this
is controversial. After the great feedback from Lorenzo on the prctl series, the
approach would be for userpsace to make a call that just does for_each_vma of the process,
madvises the VMAs, and changes the mm->def_flags for the process. We are not making changes
to the pagefaulting path (thp_vma_allowable_orders has no code change which is awesome).
In terms of what the call is going to be, there has been a lot of debate (and my preference
of prctl is clear), I am ok with either with prctl or mctl, as it should not change
the actual implementation. If there is consensus, I would love to send a RFC for how the
prctl or mctl solution would look like.
[1] https://lore.kernel.org/all/20240830100438.3623486-1-usamaarif642@gmail.com/
[2] https://lore.kernel.org/all/20250313210647.1314586-1-hannes@cmpxchg.org/
[3] https://lore.kernel.org/all/20240320180429.678181-1-hannes@cmpxchg.org/
[4] https://lore.kernel.org/linux-mm/20241030083311.965933-1-gutierrez.asier@huawei-partners.com/
[5] https://lore.kernel.org/all/20250520060504.20251-1-laoar.shao@gmail.com/
Thanks,
Usama
^ permalink raw reply
* Re: [PATCH v6 6/6] fs: introduce file_getattr and file_setattr syscalls
From: Amir Goldstein @ 2025-07-02 13:43 UTC (permalink / raw)
To: Christian Brauner
Cc: Darrick J. Wong, Andrey Albershteyn, Arnd Bergmann,
Casey Schaufler, Jan Kara, Pali Rohár, Paul Moore, linux-api,
linux-fsdevel, linux-kernel, linux-xfs, selinux,
Andrey Albershteyn
In-Reply-To: <20250702-stagnation-dackel-294bb4cd9f3d@brauner>
On Wed, Jul 2, 2025 at 2:40 PM Christian Brauner <brauner@kernel.org> wrote:
>
> > Er... "fsx_fileattr" is the struct that the system call uses?
> >
> > That's a little confusing considering that xfs already has a
> > xfs_fill_fsxattr function that actually fills a struct fileattr.
> > That could be renamed xfs_fill_fileattr.
> >
> > I dunno. There's a part of me that would really rather that the
> > file_getattr and file_setattr syscalls operate on a struct file_attr.
>
> Agreed, I'm pretty sure I suggested this during an earlier review. Fits
> in line with struct mount_attr and others. Fwiw, struct fileattr (the
> kernel internal thing) should've really been struct file_kattr or struct
> kernel_file_attr. This is a common pattern now:
>
> struct mount_attr vs struct mount_kattr
>
> struct clone_args vs struct kernel_clone_kargs
>
> etc.
>file_attr
I can see the allure, but we have a long history here with fsxattr,
so I think it serves the users better to reference this history with
fsxattr64.
That, and also, avoid the churn of s/fileattr/file_kattr/
If you want to do this renaming, please do it in the same PR
because I don't like the idea of having both file_attr and fileattr
in the tree for an unknown period.
Thanks,
Amir.
^ permalink raw reply
* Re: [PATCH v6 6/6] fs: introduce file_getattr and file_setattr syscalls
From: Christian Brauner @ 2025-07-02 12:40 UTC (permalink / raw)
To: Darrick J. Wong
Cc: Andrey Albershteyn, Amir Goldstein, Arnd Bergmann,
Casey Schaufler, Jan Kara, Pali Rohár, Paul Moore, linux-api,
linux-fsdevel, linux-kernel, linux-xfs, selinux,
Andrey Albershteyn
In-Reply-To: <20250701184317.GQ10009@frogsfrogsfrogs>
> Er... "fsx_fileattr" is the struct that the system call uses?
>
> That's a little confusing considering that xfs already has a
> xfs_fill_fsxattr function that actually fills a struct fileattr.
> That could be renamed xfs_fill_fileattr.
>
> I dunno. There's a part of me that would really rather that the
> file_getattr and file_setattr syscalls operate on a struct file_attr.
Agreed, I'm pretty sure I suggested this during an earlier review. Fits
in line with struct mount_attr and others. Fwiw, struct fileattr (the
kernel internal thing) should've really been struct file_kattr or struct
kernel_file_attr. This is a common pattern now:
struct mount_attr vs struct mount_kattr
struct clone_args vs struct kernel_clone_kargs
etc.
>
> More whining/bikeshedding to come.
>
> <snip stuff that looks ok to me>
>
> <<well, I still dislike the CLASS(fd, fd)(fd) syntax...>>
Noted, and duly ignored...
>
> > diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
> > index 0098b0ce8ccb..0784f2033ba4 100644
> > --- a/include/uapi/linux/fs.h
> > +++ b/include/uapi/linux/fs.h
> > @@ -148,6 +148,24 @@ struct fsxattr {
> > unsigned char fsx_pad[8];
> > };
> >
> > +/*
> > + * Variable size structure for file_[sg]et_attr().
> > + *
> > + * Note. This is alternative to the structure 'struct fileattr'/'struct fsxattr'.
> > + * As this structure is passed to/from userspace with its size, this can
> > + * be versioned based on the size.
> > + */
> > +struct fsx_fileattr {
> > + __u32 fsx_xflags; /* xflags field value (get/set) */
>
> Should this to be __u64 from the start? Seeing as (a) this struct is
Agreed. I changed that.
^ permalink raw reply
* Re: [PATCH v6 5/6] fs: prepare for extending file_get/setattr()
From: Christian Brauner @ 2025-07-02 12:24 UTC (permalink / raw)
To: Amir Goldstein
Cc: Pali Rohár, Darrick J. Wong, Andrey Albershteyn,
Arnd Bergmann, Casey Schaufler, Jan Kara, Paul Moore, linux-api,
linux-fsdevel, linux-kernel, linux-xfs, selinux,
Andrey Albershteyn
In-Reply-To: <CAOQ4uxhrW--Du4XvSWficnRenv24U4hwnCQtNsH4F5d4jaPjFg@mail.gmail.com>
> Christian,
>
> Can you please amend the return value in the following chunk:
>
> @@ -119,11 +120,16 @@ static int copy_fsxattr_from_user(struct fileattr *fa,
> struct fsxattr __user *ufa)
> {
> struct fsxattr xfa;
> + __u32 mask = FS_XFLAGS_MASK;
>
> if (copy_from_user(&xfa, ufa, sizeof(xfa)))
> return -EFAULT;
>
> + if (xfa.fsx_xflags & ~mask)
> + return -EOPNOTSUPP;
> +
Done.
^ permalink raw reply
* [PATCH v18 8/8] selftests/clone3: Test shadow stack support
From: Mark Brown @ 2025-07-02 10:39 UTC (permalink / raw)
To: Rick P. Edgecombe, Deepak Gupta, Szabolcs Nagy, H.J. Lu,
Florian Weimer, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Dave Hansen, x86, H. Peter Anvin, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Valentin Schneider, Christian Brauner, Shuah Khan
Cc: linux-kernel, Catalin Marinas, Will Deacon, jannh, bsegall,
Andrew Morton, Yury Khrustalev, Wilco Dijkstra, linux-kselftest,
linux-api, Mark Brown, Kees Cook, Shuah Khan
In-Reply-To: <20250702-clone3-shadow-stack-v18-0-7965d2b694db@kernel.org>
Add basic test coverage for specifying the shadow stack for a newly
created thread via clone3(), including coverage of the newly extended
argument structure. We check that a user specified shadow stack can be
provided, and that invalid combinations of parameters are rejected.
In order to facilitate testing on systems without userspace shadow stack
support we manually enable shadow stacks on startup, this is architecture
specific due to the use of an arch_prctl() on x86. Due to interactions with
potential userspace locking of features we actually detect support for
shadow stacks on the running system by attempting to allocate a shadow
stack page during initialisation using map_shadow_stack(), warning if this
succeeds when the enable failed.
In order to allow testing of user configured shadow stacks on
architectures with that feature we need to ensure that we do not return
from the function where the clone3() syscall is called in the child
process, doing so would trigger a shadow stack underflow. To do this we
use inline assembly rather than the standard syscall wrapper to call
clone3(). In order to avoid surprises we also use a syscall rather than
the libc exit() function., this should be overly cautious.
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
tools/testing/selftests/clone3/clone3.c | 143 +++++++++++++++++++++-
tools/testing/selftests/clone3/clone3_selftests.h | 63 ++++++++++
2 files changed, 205 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c
index 5b8b7d640e70..6fd2b3238e2c 100644
--- a/tools/testing/selftests/clone3/clone3.c
+++ b/tools/testing/selftests/clone3/clone3.c
@@ -3,6 +3,7 @@
/* Based on Christian Brauner's clone3() example */
#define _GNU_SOURCE
+#include <asm/mman.h>
#include <errno.h>
#include <inttypes.h>
#include <linux/types.h>
@@ -11,6 +12,7 @@
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
+#include <sys/mman.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/un.h>
@@ -19,8 +21,12 @@
#include <sched.h>
#include "../kselftest.h"
+#include "../ksft_shstk.h"
#include "clone3_selftests.h"
+static bool shadow_stack_supported;
+static size_t max_supported_args_size;
+
enum test_mode {
CLONE3_ARGS_NO_TEST,
CLONE3_ARGS_ALL_0,
@@ -28,6 +34,10 @@ enum test_mode {
CLONE3_ARGS_INVAL_EXIT_SIGNAL_NEG,
CLONE3_ARGS_INVAL_EXIT_SIGNAL_CSIG,
CLONE3_ARGS_INVAL_EXIT_SIGNAL_NSIG,
+ CLONE3_ARGS_SHADOW_STACK,
+ CLONE3_ARGS_SHADOW_STACK_MISALIGNED,
+ CLONE3_ARGS_SHADOW_STACK_NO_TOKEN,
+ CLONE3_ARGS_SHADOW_STACK_NORMAL_MEMORY,
};
typedef bool (*filter_function)(void);
@@ -44,6 +54,44 @@ struct test {
filter_function filter;
};
+
+/*
+ * We check for shadow stack support by attempting to use
+ * map_shadow_stack() since features may have been locked by the
+ * dynamic linker resulting in spurious errors when we attempt to
+ * enable on startup. We warn if the enable failed.
+ */
+static void test_shadow_stack_supported(void)
+{
+ long ret;
+
+ ret = syscall(__NR_map_shadow_stack, 0, getpagesize(), 0);
+ if (ret == -1) {
+ ksft_print_msg("map_shadow_stack() not supported\n");
+ } else if ((void *)ret == MAP_FAILED) {
+ ksft_print_msg("Failed to map shadow stack\n");
+ } else {
+ ksft_print_msg("Shadow stack supportd\n");
+ shadow_stack_supported = true;
+
+ if (!shadow_stack_enabled)
+ ksft_print_msg("Mapped but did not enable shadow stack\n");
+ }
+}
+
+static void *get_shadow_stack_page(unsigned long flags)
+{
+ unsigned long long page;
+
+ page = syscall(__NR_map_shadow_stack, 0, getpagesize(), flags);
+ if ((void *)page == MAP_FAILED) {
+ ksft_print_msg("map_shadow_stack() failed: %d\n", errno);
+ return 0;
+ }
+
+ return (void *)page;
+}
+
static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode)
{
struct __clone_args args = {
@@ -57,6 +105,7 @@ static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode)
} args_ext;
pid_t pid = -1;
+ void *p;
int status;
memset(&args_ext, 0, sizeof(args_ext));
@@ -89,6 +138,26 @@ static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode)
case CLONE3_ARGS_INVAL_EXIT_SIGNAL_NSIG:
args.exit_signal = 0x00000000000000f0ULL;
break;
+ case CLONE3_ARGS_SHADOW_STACK:
+ p = get_shadow_stack_page(SHADOW_STACK_SET_TOKEN);
+ p += getpagesize() - sizeof(void *);
+ args.shadow_stack_token = (unsigned long long)p;
+ break;
+ case CLONE3_ARGS_SHADOW_STACK_MISALIGNED:
+ p = get_shadow_stack_page(SHADOW_STACK_SET_TOKEN);
+ p += getpagesize() - sizeof(void *) - 1;
+ args.shadow_stack_token = (unsigned long long)p;
+ break;
+ case CLONE3_ARGS_SHADOW_STACK_NORMAL_MEMORY:
+ p = malloc(getpagesize());
+ p += getpagesize() - sizeof(void *);
+ args.shadow_stack_token = (unsigned long long)p;
+ break;
+ case CLONE3_ARGS_SHADOW_STACK_NO_TOKEN:
+ p = get_shadow_stack_page(0);
+ p += getpagesize() - sizeof(void *);
+ args.shadow_stack_token = (unsigned long long)p;
+ break;
}
memcpy(&args_ext.args, &args, sizeof(struct __clone_args));
@@ -102,7 +171,12 @@ static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode)
if (pid == 0) {
ksft_print_msg("I am the child, my PID is %d\n", getpid());
- _exit(EXIT_SUCCESS);
+ /*
+ * Use a raw syscall to ensure we don't get issues
+ * with manually specified shadow stack and exit handlers.
+ */
+ syscall(__NR_exit, EXIT_SUCCESS);
+ ksft_print_msg("CHILD FAILED TO EXIT PID is %d\n", getpid());
}
ksft_print_msg("I am the parent (%d). My child's pid is %d\n",
@@ -184,6 +258,26 @@ static bool no_timenamespace(void)
return true;
}
+static bool have_shadow_stack(void)
+{
+ if (shadow_stack_supported) {
+ ksft_print_msg("Shadow stack supported\n");
+ return true;
+ }
+
+ return false;
+}
+
+static bool no_shadow_stack(void)
+{
+ if (!shadow_stack_supported) {
+ ksft_print_msg("Shadow stack not supported\n");
+ return true;
+ }
+
+ return false;
+}
+
static size_t page_size_plus_8(void)
{
return getpagesize() + 8;
@@ -327,6 +421,50 @@ static const struct test tests[] = {
.expected = -EINVAL,
.test_mode = CLONE3_ARGS_NO_TEST,
},
+ {
+ .name = "Shadow stack on system with shadow stack",
+ .size = 0,
+ .expected = 0,
+ .e2big_valid = true,
+ .test_mode = CLONE3_ARGS_SHADOW_STACK,
+ .filter = no_shadow_stack,
+ },
+ {
+ .name = "Shadow stack with misaligned address",
+ .flags = CLONE_VM,
+ .size = 0,
+ .expected = -EINVAL,
+ .e2big_valid = true,
+ .test_mode = CLONE3_ARGS_SHADOW_STACK_MISALIGNED,
+ .filter = no_shadow_stack,
+ },
+ {
+ .name = "Shadow stack with normal memory",
+ .flags = CLONE_VM,
+ .size = 0,
+ .expected = -EFAULT,
+ .e2big_valid = true,
+ .test_mode = CLONE3_ARGS_SHADOW_STACK_NORMAL_MEMORY,
+ .filter = no_shadow_stack,
+ },
+ {
+ .name = "Shadow stack with no token",
+ .flags = CLONE_VM,
+ .size = 0,
+ .expected = -EINVAL,
+ .e2big_valid = true,
+ .test_mode = CLONE3_ARGS_SHADOW_STACK_NO_TOKEN,
+ .filter = no_shadow_stack,
+ },
+ {
+ .name = "Shadow stack on system without shadow stack",
+ .flags = CLONE_VM,
+ .size = 0,
+ .expected = -EFAULT,
+ .e2big_valid = true,
+ .test_mode = CLONE3_ARGS_SHADOW_STACK_NORMAL_MEMORY,
+ .filter = have_shadow_stack,
+ },
};
int main(int argc, char *argv[])
@@ -334,9 +472,12 @@ int main(int argc, char *argv[])
size_t size;
int i;
+ enable_shadow_stack();
+
ksft_print_header();
ksft_set_plan(ARRAY_SIZE(tests));
test_clone3_supported();
+ test_shadow_stack_supported();
for (i = 0; i < ARRAY_SIZE(tests); i++)
test_clone3(&tests[i]);
diff --git a/tools/testing/selftests/clone3/clone3_selftests.h b/tools/testing/selftests/clone3/clone3_selftests.h
index 939b26c86d42..8151c4fc971a 100644
--- a/tools/testing/selftests/clone3/clone3_selftests.h
+++ b/tools/testing/selftests/clone3/clone3_selftests.h
@@ -31,12 +31,75 @@ struct __clone_args {
__aligned_u64 set_tid;
__aligned_u64 set_tid_size;
__aligned_u64 cgroup;
+#ifndef CLONE_ARGS_SIZE_VER2
+#define CLONE_ARGS_SIZE_VER2 88 /* sizeof third published struct */
+#endif
+ __aligned_u64 shadow_stack_token;
+#ifndef CLONE_ARGS_SIZE_VER3
+#define CLONE_ARGS_SIZE_VER3 96 /* sizeof fourth published struct */
+#endif
};
+/*
+ * For architectures with shadow stack support we need to be
+ * absolutely sure that the clone3() syscall will be inline and not a
+ * function call so we open code.
+ */
+#ifdef __x86_64__
+static __always_inline pid_t sys_clone3(struct __clone_args *args, size_t size)
+{
+ register long _num __asm__ ("rax") = __NR_clone3;
+ register long _args __asm__ ("rdi") = (long)(args);
+ register long _size __asm__ ("rsi") = (long)(size);
+ long ret;
+
+ __asm__ volatile (
+ "syscall\n"
+ : "=a"(ret)
+ : "r"(_args), "r"(_size),
+ "0"(_num)
+ : "rcx", "r11", "memory", "cc"
+ );
+
+ if (ret < 0) {
+ errno = -ret;
+ return -1;
+ }
+
+ return ret;
+}
+#elif defined(__aarch64__)
+static __always_inline pid_t sys_clone3(struct __clone_args *args, size_t size)
+{
+ register long _num __asm__ ("x8") = __NR_clone3;
+ register long _args __asm__ ("x0") = (long)(args);
+ register long _size __asm__ ("x1") = (long)(size);
+ register long arg2 __asm__ ("x2") = 0;
+ register long arg3 __asm__ ("x3") = 0;
+ register long arg4 __asm__ ("x4") = 0;
+
+ __asm__ volatile (
+ "svc #0\n"
+ : "=r"(_args)
+ : "r"(_args), "r"(_size),
+ "r"(_num), "r"(arg2),
+ "r"(arg3), "r"(arg4)
+ : "memory", "cc"
+ );
+
+ if ((int)_args < 0) {
+ errno = -((int)_args);
+ return -1;
+ }
+
+ return _args;
+}
+#else
static pid_t sys_clone3(struct __clone_args *args, size_t size)
{
return syscall(__NR_clone3, args, size);
}
+#endif
static inline void test_clone3_supported(void)
{
--
2.39.5
^ permalink raw reply related
* [PATCH v18 7/8] selftests/clone3: Allow tests to flag if -E2BIG is a valid error code
From: Mark Brown @ 2025-07-02 10:39 UTC (permalink / raw)
To: Rick P. Edgecombe, Deepak Gupta, Szabolcs Nagy, H.J. Lu,
Florian Weimer, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Dave Hansen, x86, H. Peter Anvin, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Valentin Schneider, Christian Brauner, Shuah Khan
Cc: linux-kernel, Catalin Marinas, Will Deacon, jannh, bsegall,
Andrew Morton, Yury Khrustalev, Wilco Dijkstra, linux-kselftest,
linux-api, Mark Brown, Kees Cook, Kees Cook, Shuah Khan
In-Reply-To: <20250702-clone3-shadow-stack-v18-0-7965d2b694db@kernel.org>
The clone_args structure is extensible, with the syscall passing in the
length of the structure. Inside the kernel we use copy_struct_from_user()
to read the struct but this has the unfortunate side effect of silently
accepting some overrun in the structure size providing the extra data is
all zeros. This means that we can't discover the clone3() features that
the running kernel supports by simply probing with various struct sizes.
We need to check this for the benefit of test systems which run newer
kselftests on old kernels.
Add a flag which can be set on a test to indicate that clone3() may return
-E2BIG due to the use of newer struct versions. Currently no tests need
this but it will become an issue for testing clone3() support for shadow
stacks, the support for shadow stacks is already present on x86.
Reviewed-by: Kees Cook <kees@kernel.org>
Tested-by: Kees Cook <kees@kernel.org>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
tools/testing/selftests/clone3/clone3.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c
index e066b201fa64..5b8b7d640e70 100644
--- a/tools/testing/selftests/clone3/clone3.c
+++ b/tools/testing/selftests/clone3/clone3.c
@@ -39,6 +39,7 @@ struct test {
size_t size;
size_function size_function;
int expected;
+ bool e2big_valid;
enum test_mode test_mode;
filter_function filter;
};
@@ -146,6 +147,11 @@ static void test_clone3(const struct test *test)
ksft_print_msg("[%d] clone3() with flags says: %d expected %d\n",
getpid(), ret, test->expected);
if (ret != test->expected) {
+ if (test->e2big_valid && ret == -E2BIG) {
+ ksft_print_msg("Test reported -E2BIG\n");
+ ksft_test_result_skip("%s\n", test->name);
+ return;
+ }
ksft_print_msg(
"[%d] Result (%d) is different than expected (%d)\n",
getpid(), ret, test->expected);
--
2.39.5
^ permalink raw reply related
* [PATCH v18 6/8] selftests/clone3: Factor more of main loop into test_clone3()
From: Mark Brown @ 2025-07-02 10:39 UTC (permalink / raw)
To: Rick P. Edgecombe, Deepak Gupta, Szabolcs Nagy, H.J. Lu,
Florian Weimer, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Dave Hansen, x86, H. Peter Anvin, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Valentin Schneider, Christian Brauner, Shuah Khan
Cc: linux-kernel, Catalin Marinas, Will Deacon, jannh, bsegall,
Andrew Morton, Yury Khrustalev, Wilco Dijkstra, linux-kselftest,
linux-api, Mark Brown, Kees Cook, Kees Cook, Shuah Khan
In-Reply-To: <20250702-clone3-shadow-stack-v18-0-7965d2b694db@kernel.org>
In order to make it easier to add more configuration for the tests and
more support for runtime detection of when tests can be run pass the
structure describing the tests into test_clone3() rather than picking
the arguments out of it and have that function do all the per-test work.
No functional change.
Reviewed-by: Kees Cook <kees@kernel.org>
Tested-by: Kees Cook <kees@kernel.org>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
tools/testing/selftests/clone3/clone3.c | 77 ++++++++++++++++-----------------
1 file changed, 37 insertions(+), 40 deletions(-)
diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c
index e61f07973ce5..e066b201fa64 100644
--- a/tools/testing/selftests/clone3/clone3.c
+++ b/tools/testing/selftests/clone3/clone3.c
@@ -30,6 +30,19 @@ enum test_mode {
CLONE3_ARGS_INVAL_EXIT_SIGNAL_NSIG,
};
+typedef bool (*filter_function)(void);
+typedef size_t (*size_function)(void);
+
+struct test {
+ const char *name;
+ uint64_t flags;
+ size_t size;
+ size_function size_function;
+ int expected;
+ enum test_mode test_mode;
+ filter_function filter;
+};
+
static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode)
{
struct __clone_args args = {
@@ -109,30 +122,40 @@ static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode)
return 0;
}
-static bool test_clone3(uint64_t flags, size_t size, int expected,
- enum test_mode test_mode)
+static void test_clone3(const struct test *test)
{
+ size_t size;
int ret;
+ if (test->filter && test->filter()) {
+ ksft_test_result_skip("%s\n", test->name);
+ return;
+ }
+
+ if (test->size_function)
+ size = test->size_function();
+ else
+ size = test->size;
+
+ ksft_print_msg("Running test '%s'\n", test->name);
+
ksft_print_msg(
"[%d] Trying clone3() with flags %#" PRIx64 " (size %zu)\n",
- getpid(), flags, size);
- ret = call_clone3(flags, size, test_mode);
+ getpid(), test->flags, size);
+ ret = call_clone3(test->flags, size, test->test_mode);
ksft_print_msg("[%d] clone3() with flags says: %d expected %d\n",
- getpid(), ret, expected);
- if (ret != expected) {
+ getpid(), ret, test->expected);
+ if (ret != test->expected) {
ksft_print_msg(
"[%d] Result (%d) is different than expected (%d)\n",
- getpid(), ret, expected);
- return false;
+ getpid(), ret, test->expected);
+ ksft_test_result_fail("%s\n", test->name);
+ return;
}
- return true;
+ ksft_test_result_pass("%s\n", test->name);
}
-typedef bool (*filter_function)(void);
-typedef size_t (*size_function)(void);
-
static bool not_root(void)
{
if (getuid() != 0) {
@@ -160,16 +183,6 @@ static size_t page_size_plus_8(void)
return getpagesize() + 8;
}
-struct test {
- const char *name;
- uint64_t flags;
- size_t size;
- size_function size_function;
- int expected;
- enum test_mode test_mode;
- filter_function filter;
-};
-
static const struct test tests[] = {
{
.name = "simple clone3()",
@@ -319,24 +332,8 @@ int main(int argc, char *argv[])
ksft_set_plan(ARRAY_SIZE(tests));
test_clone3_supported();
- for (i = 0; i < ARRAY_SIZE(tests); i++) {
- if (tests[i].filter && tests[i].filter()) {
- ksft_test_result_skip("%s\n", tests[i].name);
- continue;
- }
-
- if (tests[i].size_function)
- size = tests[i].size_function();
- else
- size = tests[i].size;
-
- ksft_print_msg("Running test '%s'\n", tests[i].name);
-
- ksft_test_result(test_clone3(tests[i].flags, size,
- tests[i].expected,
- tests[i].test_mode),
- "%s\n", tests[i].name);
- }
+ for (i = 0; i < ARRAY_SIZE(tests); i++)
+ test_clone3(&tests[i]);
ksft_finished();
}
--
2.39.5
^ permalink raw reply related
* [PATCH v18 5/8] selftests/clone3: Remove redundant flushes of output streams
From: Mark Brown @ 2025-07-02 10:39 UTC (permalink / raw)
To: Rick P. Edgecombe, Deepak Gupta, Szabolcs Nagy, H.J. Lu,
Florian Weimer, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Dave Hansen, x86, H. Peter Anvin, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Valentin Schneider, Christian Brauner, Shuah Khan
Cc: linux-kernel, Catalin Marinas, Will Deacon, jannh, bsegall,
Andrew Morton, Yury Khrustalev, Wilco Dijkstra, linux-kselftest,
linux-api, Mark Brown, Kees Cook, Kees Cook, Shuah Khan
In-Reply-To: <20250702-clone3-shadow-stack-v18-0-7965d2b694db@kernel.org>
Since there were widespread issues with output not being flushed the
kselftest framework was modified to explicitly set the output streams
unbuffered in commit 58e2847ad2e6 ("selftests: line buffer test
program's stdout") so there is no need to explicitly flush in the clone3
tests.
Reviewed-by: Kees Cook <kees@kernel.org>
Tested-by: Kees Cook <kees@kernel.org>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
tools/testing/selftests/clone3/clone3_selftests.h | 2 --
1 file changed, 2 deletions(-)
diff --git a/tools/testing/selftests/clone3/clone3_selftests.h b/tools/testing/selftests/clone3/clone3_selftests.h
index eeca8005723f..939b26c86d42 100644
--- a/tools/testing/selftests/clone3/clone3_selftests.h
+++ b/tools/testing/selftests/clone3/clone3_selftests.h
@@ -35,8 +35,6 @@ struct __clone_args {
static pid_t sys_clone3(struct __clone_args *args, size_t size)
{
- fflush(stdout);
- fflush(stderr);
return syscall(__NR_clone3, args, size);
}
--
2.39.5
^ permalink raw reply related
* [PATCH v18 4/8] fork: Add shadow stack support to clone3()
From: Mark Brown @ 2025-07-02 10:39 UTC (permalink / raw)
To: Rick P. Edgecombe, Deepak Gupta, Szabolcs Nagy, H.J. Lu,
Florian Weimer, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Dave Hansen, x86, H. Peter Anvin, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Valentin Schneider, Christian Brauner, Shuah Khan
Cc: linux-kernel, Catalin Marinas, Will Deacon, jannh, bsegall,
Andrew Morton, Yury Khrustalev, Wilco Dijkstra, linux-kselftest,
linux-api, Mark Brown, Kees Cook
In-Reply-To: <20250702-clone3-shadow-stack-v18-0-7965d2b694db@kernel.org>
Unlike with the normal stack there is no API for configuring the shadow
stack for a new thread, instead the kernel will dynamically allocate a
new shadow stack with the same size as the normal stack. This appears to
be due to the shadow stack series having been in development since
before the more extensible clone3() was added rather than anything more
deliberate.
Add a parameter to clone3() specifying a shadow stack pointer to use
for the new thread, this is inconsistent with the way we specify the
normal stack but during review concerns were expressed about having to
identify where the shadow stack pointer should be placed especially in
cases where the shadow stack has been previously active. If no shadow
stack is specified then the existing implicit allocation behaviour is
maintained.
If a shadow stack pointer is specified then it is required to have an
architecture defined token placed on the stack, this will be consumed by
the new task, the shadow stack is specified by pointing to this token. If
no valid token is present then this will be reported with -EINVAL. This
token prevents new threads being created pointing at the shadow stack of
an existing running thread. On architectures with support for userspace
pivoting of shadow stacks it is expected that the same format and placement
of tokens will be used, this is the case for arm64 and x86.
If the architecture does not support shadow stacks the shadow stack
pointer must be not be specified, architectures that do support the
feature are expected to enforce the same requirement on individual
systems that lack shadow stack support.
Update the existing arm64 and x86 implementations to pay attention to
the newly added arguments, in order to maintain compatibility we use the
existing behaviour if no shadow stack is specified. Since we are now
using more fields from the kernel_clone_args we pass that into the
shadow stack code rather than individual fields.
Portions of the x86 architecture code were written by Rick Edgecombe.
Acked-by: Yury Khrustalev <yury.khrustalev@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/mm/gcs.c | 47 +++++++++++++++++++-
arch/x86/include/asm/shstk.h | 11 +++--
arch/x86/kernel/process.c | 2 +-
arch/x86/kernel/shstk.c | 53 ++++++++++++++++++++---
include/asm-generic/cacheflush.h | 11 +++++
include/linux/sched/task.h | 17 ++++++++
include/uapi/linux/sched.h | 9 ++--
kernel/fork.c | 93 ++++++++++++++++++++++++++++++++++------
8 files changed, 217 insertions(+), 26 deletions(-)
diff --git a/arch/arm64/mm/gcs.c b/arch/arm64/mm/gcs.c
index 1f633a482558..884ae663ba96 100644
--- a/arch/arm64/mm/gcs.c
+++ b/arch/arm64/mm/gcs.c
@@ -43,8 +43,23 @@ int gcs_alloc_thread_stack(struct task_struct *tsk,
{
unsigned long addr, size;
- if (!system_supports_gcs())
+ if (!system_supports_gcs()) {
+ if (args->shadow_stack_token)
+ return -EINVAL;
+
return 0;
+ }
+
+ /*
+ * If the user specified a GCS then use it, otherwise fall
+ * back to a default allocation strategy. Validation is done
+ * in arch_shstk_validate_clone().
+ */
+ if (args->shadow_stack_token) {
+ tsk->thread.gcs_base = 0;
+ tsk->thread.gcs_size = 0;
+ return 0;
+ }
if (!task_gcs_el0_enabled(tsk))
return 0;
@@ -68,6 +83,36 @@ int gcs_alloc_thread_stack(struct task_struct *tsk,
return 0;
}
+static bool gcs_consume_token(struct vm_area_struct *vma, struct page *page,
+ unsigned long user_addr)
+{
+ u64 expected = GCS_CAP(user_addr);
+ u64 *token = page_address(page) + offset_in_page(user_addr);
+
+ if (!cmpxchg_to_user_page(vma, page, user_addr, token, expected, 0))
+ return false;
+ set_page_dirty_lock(page);
+
+ return true;
+}
+
+int arch_shstk_validate_clone(struct task_struct *tsk,
+ struct vm_area_struct *vma,
+ struct page *page,
+ struct kernel_clone_args *args)
+{
+ unsigned long gcspr_el0;
+ int ret = 0;
+
+ gcspr_el0 = args->shadow_stack_token;
+ if (!gcs_consume_token(vma, page, gcspr_el0))
+ return -EINVAL;
+
+ tsk->thread.gcspr_el0 = gcspr_el0 + sizeof(u64);
+
+ return ret;
+}
+
SYSCALL_DEFINE3(map_shadow_stack, unsigned long, addr, unsigned long, size, unsigned int, flags)
{
unsigned long alloc_size;
diff --git a/arch/x86/include/asm/shstk.h b/arch/x86/include/asm/shstk.h
index ba6f2fe43848..827e983430aa 100644
--- a/arch/x86/include/asm/shstk.h
+++ b/arch/x86/include/asm/shstk.h
@@ -6,6 +6,7 @@
#include <linux/types.h>
struct task_struct;
+struct kernel_clone_args;
struct ksignal;
#ifdef CONFIG_X86_USER_SHADOW_STACK
@@ -16,8 +17,8 @@ struct thread_shstk {
long shstk_prctl(struct task_struct *task, int option, unsigned long arg2);
void reset_thread_features(void);
-unsigned long shstk_alloc_thread_stack(struct task_struct *p, unsigned long clone_flags,
- unsigned long stack_size);
+unsigned long shstk_alloc_thread_stack(struct task_struct *p,
+ const struct kernel_clone_args *args);
void shstk_free(struct task_struct *p);
int setup_signal_shadow_stack(struct ksignal *ksig);
int restore_signal_shadow_stack(void);
@@ -28,8 +29,10 @@ static inline long shstk_prctl(struct task_struct *task, int option,
unsigned long arg2) { return -EINVAL; }
static inline void reset_thread_features(void) {}
static inline unsigned long shstk_alloc_thread_stack(struct task_struct *p,
- unsigned long clone_flags,
- unsigned long stack_size) { return 0; }
+ const struct kernel_clone_args *args)
+{
+ return 0;
+}
static inline void shstk_free(struct task_struct *p) {}
static inline int setup_signal_shadow_stack(struct ksignal *ksig) { return 0; }
static inline int restore_signal_shadow_stack(void) { return 0; }
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 704883c21f3a..56bf3394360a 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -209,7 +209,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
* is disabled, new_ssp will remain 0, and fpu_clone() will know not to
* update it.
*/
- new_ssp = shstk_alloc_thread_stack(p, clone_flags, args->stack_size);
+ new_ssp = shstk_alloc_thread_stack(p, args);
if (IS_ERR_VALUE(new_ssp))
return PTR_ERR((void *)new_ssp);
diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c
index 2ddf23387c7e..88ca9eaebc96 100644
--- a/arch/x86/kernel/shstk.c
+++ b/arch/x86/kernel/shstk.c
@@ -191,18 +191,61 @@ void reset_thread_features(void)
current->thread.features_locked = 0;
}
-unsigned long shstk_alloc_thread_stack(struct task_struct *tsk, unsigned long clone_flags,
- unsigned long stack_size)
+int arch_shstk_validate_clone(struct task_struct *t,
+ struct vm_area_struct *vma,
+ struct page *page,
+ struct kernel_clone_args *args)
+{
+ /*
+ * SSP is aligned, so reserved bits and mode bit are a zero, just mark
+ * the token 64-bit.
+ */
+ void *maddr = page_address(page);
+ unsigned long token;
+ int offset;
+ u64 expected;
+
+ token = args->shadow_stack_token;
+ expected = (token + SS_FRAME_SIZE) | BIT(0);
+ offset = offset_in_page(token);
+
+ if (!cmpxchg_to_user_page(vma, page, token, (unsigned long *)(maddr + offset),
+ expected, 0))
+ return -EINVAL;
+ set_page_dirty_lock(page);
+
+ return 0;
+}
+
+unsigned long shstk_alloc_thread_stack(struct task_struct *tsk,
+ const struct kernel_clone_args *args)
{
struct thread_shstk *shstk = &tsk->thread.shstk;
+ unsigned long clone_flags = args->flags;
unsigned long addr, size;
/*
* If shadow stack is not enabled on the new thread, skip any
- * switch to a new shadow stack.
+ * implicit switch to a new shadow stack and reject attempts to
+ * explicitly specify one.
*/
- if (!features_enabled(ARCH_SHSTK_SHSTK))
+ if (!features_enabled(ARCH_SHSTK_SHSTK)) {
+ if (args->shadow_stack_token)
+ return (unsigned long)ERR_PTR(-EINVAL);
+
return 0;
+ }
+
+ /*
+ * If the user specified a shadow stack then use it, otherwise
+ * fall back to a default allocation strategy. Validation is
+ * done in arch_shstk_validate_clone().
+ */
+ if (args->shadow_stack_token) {
+ shstk->base = 0;
+ shstk->size = 0;
+ return args->shadow_stack_token + 8;
+ }
/*
* For CLONE_VFORK the child will share the parents shadow stack.
@@ -222,7 +265,7 @@ unsigned long shstk_alloc_thread_stack(struct task_struct *tsk, unsigned long cl
if (!(clone_flags & CLONE_VM))
return 0;
- size = adjust_shstk_size(stack_size);
+ size = adjust_shstk_size(args->stack_size);
addr = alloc_shstk(0, size, 0, false);
if (IS_ERR_VALUE(addr))
return addr;
diff --git a/include/asm-generic/cacheflush.h b/include/asm-generic/cacheflush.h
index 7ee8a179d103..96cc0c7a5c90 100644
--- a/include/asm-generic/cacheflush.h
+++ b/include/asm-generic/cacheflush.h
@@ -124,4 +124,15 @@ static inline void flush_cache_vunmap(unsigned long start, unsigned long end)
} while (0)
#endif
+#ifndef cmpxchg_to_user_page
+#define cmpxchg_to_user_page(vma, page, vaddr, ptr, old, new) \
+({ \
+ bool ret; \
+ \
+ ret = try_cmpxchg(ptr, &old, new); \
+ flush_icache_user_page(vma, page, vaddr, sizeof(*ptr)); \
+ ret; \
+})
+#endif
+
#endif /* _ASM_GENERIC_CACHEFLUSH_H */
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index ca1db4b92c32..c34f3cb68822 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -16,6 +16,7 @@ struct task_struct;
struct rusage;
union thread_union;
struct css_set;
+struct vm_area_struct;
/* All the bits taken by the old clone syscall. */
#define CLONE_LEGACY_FLAGS 0xffffffffULL
@@ -44,6 +45,7 @@ struct kernel_clone_args {
struct cgroup *cgrp;
struct css_set *cset;
unsigned int kill_seq;
+ unsigned long shadow_stack_token;
};
/*
@@ -237,4 +239,19 @@ static inline void task_unlock(struct task_struct *p)
DEFINE_GUARD(task_lock, struct task_struct *, task_lock(_T), task_unlock(_T))
+#ifdef CONFIG_ARCH_HAS_USER_SHADOW_STACK
+int arch_shstk_validate_clone(struct task_struct *p,
+ struct vm_area_struct *vma,
+ struct page *page,
+ struct kernel_clone_args *args);
+#else
+static inline int arch_shstk_validate_clone(struct task_struct *p,
+ struct vm_area_struct *vma,
+ struct page *page,
+ struct kernel_clone_args *args)
+{
+ return 0;
+}
+#endif
+
#endif /* _LINUX_SCHED_TASK_H */
diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h
index 359a14cc76a4..9cf5c419e109 100644
--- a/include/uapi/linux/sched.h
+++ b/include/uapi/linux/sched.h
@@ -84,6 +84,7 @@
* kernel's limit of nested PID namespaces.
* @cgroup: If CLONE_INTO_CGROUP is specified set this to
* a file descriptor for the cgroup.
+ * @shadow_stack_token: Pointer to shadow stack token at top of stack.
*
* The structure is versioned by size and thus extensible.
* New struct members must go at the end of the struct and
@@ -101,12 +102,14 @@ struct clone_args {
__aligned_u64 set_tid;
__aligned_u64 set_tid_size;
__aligned_u64 cgroup;
+ __aligned_u64 shadow_stack_token;
};
#endif
-#define CLONE_ARGS_SIZE_VER0 64 /* sizeof first published struct */
-#define CLONE_ARGS_SIZE_VER1 80 /* sizeof second published struct */
-#define CLONE_ARGS_SIZE_VER2 88 /* sizeof third published struct */
+#define CLONE_ARGS_SIZE_VER0 64 /* sizeof first published struct */
+#define CLONE_ARGS_SIZE_VER1 80 /* sizeof second published struct */
+#define CLONE_ARGS_SIZE_VER2 88 /* sizeof third published struct */
+#define CLONE_ARGS_SIZE_VER3 96 /* sizeof fourth published struct */
/*
* Scheduling policies
diff --git a/kernel/fork.c b/kernel/fork.c
index 1ee8eb11f38b..728f9b037853 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1902,6 +1902,51 @@ static bool need_futex_hash_allocate_default(u64 clone_flags)
return true;
}
+static int shstk_validate_clone(struct task_struct *p,
+ struct kernel_clone_args *args)
+{
+ struct mm_struct *mm;
+ struct vm_area_struct *vma;
+ struct page *page;
+ unsigned long addr;
+ int ret;
+
+ if (!IS_ENABLED(CONFIG_ARCH_HAS_USER_SHADOW_STACK))
+ return 0;
+
+ if (!args->shadow_stack_token)
+ return 0;
+
+ mm = get_task_mm(p);
+ if (!mm)
+ return -EFAULT;
+
+ mmap_read_lock(mm);
+
+ addr = untagged_addr_remote(mm, args->shadow_stack_token);
+ page = get_user_page_vma_remote(mm, addr, FOLL_FORCE | FOLL_WRITE,
+ &vma);
+ if (IS_ERR(page)) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ if (!(vma->vm_flags & VM_SHADOW_STACK) ||
+ !(vma->vm_flags & VM_WRITE)) {
+ ret = -EFAULT;
+ goto out_page;
+ }
+
+ ret = arch_shstk_validate_clone(p, vma, page, args);
+
+out_page:
+ put_page(page);
+out:
+ mmap_read_unlock(mm);
+ mmput(mm);
+ return ret;
+}
+
/*
* This creates a new process as a copy of the old one,
* but does not actually start it yet.
@@ -2176,6 +2221,9 @@ __latent_entropy struct task_struct *copy_process(
if (retval)
goto bad_fork_cleanup_namespaces;
retval = copy_thread(p, args);
+ if (retval)
+ goto bad_fork_cleanup_io;
+ retval = shstk_validate_clone(p, args);
if (retval)
goto bad_fork_cleanup_io;
@@ -2757,7 +2805,9 @@ noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
CLONE_ARGS_SIZE_VER1);
BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
CLONE_ARGS_SIZE_VER2);
- BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
+ BUILD_BUG_ON(offsetofend(struct clone_args, shadow_stack_token) !=
+ CLONE_ARGS_SIZE_VER3);
+ BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER3);
if (unlikely(usize > PAGE_SIZE))
return -E2BIG;
@@ -2790,16 +2840,17 @@ noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
return -EINVAL;
*kargs = (struct kernel_clone_args){
- .flags = args.flags,
- .pidfd = u64_to_user_ptr(args.pidfd),
- .child_tid = u64_to_user_ptr(args.child_tid),
- .parent_tid = u64_to_user_ptr(args.parent_tid),
- .exit_signal = args.exit_signal,
- .stack = args.stack,
- .stack_size = args.stack_size,
- .tls = args.tls,
- .set_tid_size = args.set_tid_size,
- .cgroup = args.cgroup,
+ .flags = args.flags,
+ .pidfd = u64_to_user_ptr(args.pidfd),
+ .child_tid = u64_to_user_ptr(args.child_tid),
+ .parent_tid = u64_to_user_ptr(args.parent_tid),
+ .exit_signal = args.exit_signal,
+ .stack = args.stack,
+ .stack_size = args.stack_size,
+ .tls = args.tls,
+ .set_tid_size = args.set_tid_size,
+ .cgroup = args.cgroup,
+ .shadow_stack_token = args.shadow_stack_token,
};
if (args.set_tid &&
@@ -2840,6 +2891,24 @@ static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
return true;
}
+/**
+ * clone3_shadow_stack_valid - check and prepare shadow stack
+ * @kargs: kernel clone args
+ *
+ * Verify that shadow stacks are only enabled if supported.
+ */
+static inline bool clone3_shadow_stack_valid(struct kernel_clone_args *kargs)
+{
+ if (!kargs->shadow_stack_token)
+ return true;
+
+ if (!IS_ALIGNED(kargs->shadow_stack_token, sizeof(void *)))
+ return false;
+
+ /* Fail if the kernel wasn't built with shadow stacks */
+ return IS_ENABLED(CONFIG_ARCH_HAS_USER_SHADOW_STACK);
+}
+
static bool clone3_args_valid(struct kernel_clone_args *kargs)
{
/* Verify that no unknown flags are passed along. */
@@ -2862,7 +2931,7 @@ static bool clone3_args_valid(struct kernel_clone_args *kargs)
kargs->exit_signal)
return false;
- if (!clone3_stack_valid(kargs))
+ if (!clone3_stack_valid(kargs) || !clone3_shadow_stack_valid(kargs))
return false;
return true;
--
2.39.5
^ permalink raw reply related
* [PATCH v18 3/8] selftests: Provide helper header for shadow stack testing
From: Mark Brown @ 2025-07-02 10:39 UTC (permalink / raw)
To: Rick P. Edgecombe, Deepak Gupta, Szabolcs Nagy, H.J. Lu,
Florian Weimer, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Dave Hansen, x86, H. Peter Anvin, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Valentin Schneider, Christian Brauner, Shuah Khan
Cc: linux-kernel, Catalin Marinas, Will Deacon, jannh, bsegall,
Andrew Morton, Yury Khrustalev, Wilco Dijkstra, linux-kselftest,
linux-api, Mark Brown, Kees Cook, Kees Cook, Shuah Khan
In-Reply-To: <20250702-clone3-shadow-stack-v18-0-7965d2b694db@kernel.org>
While almost all users of shadow stacks should be relying on the dynamic
linker and libc to enable the feature there are several low level test
programs where it is useful to enable without any libc support, allowing
testing without full system enablement. This low level testing is helpful
during bringup of the support itself, and also in enabling coverage by
automated testing without needing all system components in the target root
filesystems to have enablement.
Provide a header with helpers for this purpose, intended for use only by
test programs directly exercising shadow stack interfaces.
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Tested-by: Kees Cook <kees@kernel.org>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
tools/testing/selftests/ksft_shstk.h | 98 ++++++++++++++++++++++++++++++++++++
1 file changed, 98 insertions(+)
diff --git a/tools/testing/selftests/ksft_shstk.h b/tools/testing/selftests/ksft_shstk.h
new file mode 100644
index 000000000000..fecf91218ea5
--- /dev/null
+++ b/tools/testing/selftests/ksft_shstk.h
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Helpers for shadow stack enablement, this is intended to only be
+ * used by low level test programs directly exercising interfaces for
+ * working with shadow stacks.
+ *
+ * Copyright (C) 2024 ARM Ltd.
+ */
+
+#ifndef __KSFT_SHSTK_H
+#define __KSFT_SHSTK_H
+
+#include <asm/mman.h>
+
+/* This is currently only defined for x86 */
+#ifndef SHADOW_STACK_SET_TOKEN
+#define SHADOW_STACK_SET_TOKEN (1ULL << 0)
+#endif
+
+static bool shadow_stack_enabled;
+
+#ifdef __x86_64__
+#define ARCH_SHSTK_ENABLE 0x5001
+#define ARCH_SHSTK_SHSTK (1ULL << 0)
+
+#define ARCH_PRCTL(arg1, arg2) \
+({ \
+ long _ret; \
+ register long _num asm("eax") = __NR_arch_prctl; \
+ register long _arg1 asm("rdi") = (long)(arg1); \
+ register long _arg2 asm("rsi") = (long)(arg2); \
+ \
+ asm volatile ( \
+ "syscall\n" \
+ : "=a"(_ret) \
+ : "r"(_arg1), "r"(_arg2), \
+ "0"(_num) \
+ : "rcx", "r11", "memory", "cc" \
+ ); \
+ _ret; \
+})
+
+#define ENABLE_SHADOW_STACK
+static __always_inline void enable_shadow_stack(void)
+{
+ int ret = ARCH_PRCTL(ARCH_SHSTK_ENABLE, ARCH_SHSTK_SHSTK);
+ if (ret == 0)
+ shadow_stack_enabled = true;
+}
+
+#endif
+
+#ifdef __aarch64__
+#define PR_SET_SHADOW_STACK_STATUS 75
+# define PR_SHADOW_STACK_ENABLE (1UL << 0)
+
+#define my_syscall2(num, arg1, arg2) \
+({ \
+ register long _num __asm__ ("x8") = (num); \
+ register long _arg1 __asm__ ("x0") = (long)(arg1); \
+ register long _arg2 __asm__ ("x1") = (long)(arg2); \
+ register long _arg3 __asm__ ("x2") = 0; \
+ register long _arg4 __asm__ ("x3") = 0; \
+ register long _arg5 __asm__ ("x4") = 0; \
+ \
+ __asm__ volatile ( \
+ "svc #0\n" \
+ : "=r"(_arg1) \
+ : "r"(_arg1), "r"(_arg2), \
+ "r"(_arg3), "r"(_arg4), \
+ "r"(_arg5), "r"(_num) \
+ : "memory", "cc" \
+ ); \
+ _arg1; \
+})
+
+#define ENABLE_SHADOW_STACK
+static __always_inline void enable_shadow_stack(void)
+{
+ int ret;
+
+ ret = my_syscall2(__NR_prctl, PR_SET_SHADOW_STACK_STATUS,
+ PR_SHADOW_STACK_ENABLE);
+ if (ret == 0)
+ shadow_stack_enabled = true;
+}
+
+#endif
+
+#ifndef __NR_map_shadow_stack
+#define __NR_map_shadow_stack 453
+#endif
+
+#ifndef ENABLE_SHADOW_STACK
+static inline void enable_shadow_stack(void) { }
+#endif
+
+#endif
--
2.39.5
^ permalink raw reply related
* [PATCH v18 2/8] Documentation: userspace-api: Add shadow stack API documentation
From: Mark Brown @ 2025-07-02 10:39 UTC (permalink / raw)
To: Rick P. Edgecombe, Deepak Gupta, Szabolcs Nagy, H.J. Lu,
Florian Weimer, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Dave Hansen, x86, H. Peter Anvin, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Valentin Schneider, Christian Brauner, Shuah Khan
Cc: linux-kernel, Catalin Marinas, Will Deacon, jannh, bsegall,
Andrew Morton, Yury Khrustalev, Wilco Dijkstra, linux-kselftest,
linux-api, Mark Brown, Kees Cook, Kees Cook, Shuah Khan
In-Reply-To: <20250702-clone3-shadow-stack-v18-0-7965d2b694db@kernel.org>
There are a number of architectures with shadow stack features which we are
presenting to userspace with as consistent an API as we can (though there
are some architecture specifics). Especially given that there are some
important considerations for userspace code interacting directly with the
feature let's provide some documentation covering the common aspects.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Tested-by: Kees Cook <kees@kernel.org>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Yury Khrustalev <yury.khrustalev@arm.com>
Reviewed-by: Deepak Gupta <debug@rivosinc.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
Documentation/userspace-api/index.rst | 1 +
Documentation/userspace-api/shadow_stack.rst | 44 ++++++++++++++++++++++++++++
2 files changed, 45 insertions(+)
diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst
index b8c73be4fb11..0167e59b541e 100644
--- a/Documentation/userspace-api/index.rst
+++ b/Documentation/userspace-api/index.rst
@@ -62,6 +62,7 @@ Everything else
ELF
netlink/index
+ shadow_stack
sysfs-platform_profile
vduse
futex2
diff --git a/Documentation/userspace-api/shadow_stack.rst b/Documentation/userspace-api/shadow_stack.rst
new file mode 100644
index 000000000000..65c665496624
--- /dev/null
+++ b/Documentation/userspace-api/shadow_stack.rst
@@ -0,0 +1,44 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+Shadow Stacks
+=============
+
+Introduction
+============
+
+Several architectures have features which provide backward edge
+control flow protection through a hardware maintained stack, only
+writeable by userspace through very limited operations. This feature
+is referred to as shadow stacks on Linux, on x86 it is part of Intel
+Control Enforcement Technology (CET), on arm64 it is Guarded Control
+Stacks feature (FEAT_GCS) and for RISC-V it is the Zicfiss extension.
+It is expected that this feature will normally be managed by the
+system dynamic linker and libc in ways broadly transparent to
+application code, this document covers interfaces and considerations.
+
+
+Enabling
+========
+
+Shadow stacks default to disabled when a userspace process is
+executed, they can be enabled for the current thread with a syscall:
+
+ - For x86 the ARCH_SHSTK_ENABLE arch_prctl()
+ - For other architectures the PR_SET_SHADOW_STACK_ENABLE prctl()
+
+It is expected that this will normally be done by the dynamic linker.
+Any new threads created by a thread with shadow stacks enabled will
+themselves have shadow stacks enabled.
+
+
+Enablement considerations
+=========================
+
+- Returning from the function that enables shadow stacks without first
+ disabling them will cause a shadow stack exception. This includes
+ any syscall wrapper or other library functions, the syscall will need
+ to be inlined.
+- A lock feature allows userspace to prevent disabling of shadow stacks.
+- Those that change the stack context like longjmp() or use of ucontext
+ changes on signal return will need support from libc.
--
2.39.5
^ permalink raw reply related
* [PATCH v18 1/8] arm64/gcs: Return a success value from gcs_alloc_thread_stack()
From: Mark Brown @ 2025-07-02 10:39 UTC (permalink / raw)
To: Rick P. Edgecombe, Deepak Gupta, Szabolcs Nagy, H.J. Lu,
Florian Weimer, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Dave Hansen, x86, H. Peter Anvin, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Valentin Schneider, Christian Brauner, Shuah Khan
Cc: linux-kernel, Catalin Marinas, Will Deacon, jannh, bsegall,
Andrew Morton, Yury Khrustalev, Wilco Dijkstra, linux-kselftest,
linux-api, Mark Brown, Kees Cook
In-Reply-To: <20250702-clone3-shadow-stack-v18-0-7965d2b694db@kernel.org>
Currently as a result of templating from x86 code gcs_alloc_thread_stack()
returns a pointer as an unsigned int however on arm64 we don't actually use
this pointer value as anything other than a pass/fail flag. Simplify the
interface to just return an int with 0 on success and a negative error code
on failure.
Acked-by: Deepak Gupta <debug@rivosinc.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/include/asm/gcs.h | 8 ++++----
arch/arm64/kernel/process.c | 8 ++++----
arch/arm64/mm/gcs.c | 8 ++++----
3 files changed, 12 insertions(+), 12 deletions(-)
diff --git a/arch/arm64/include/asm/gcs.h b/arch/arm64/include/asm/gcs.h
index f50660603ecf..d8923b5f03b7 100644
--- a/arch/arm64/include/asm/gcs.h
+++ b/arch/arm64/include/asm/gcs.h
@@ -64,8 +64,8 @@ static inline bool task_gcs_el0_enabled(struct task_struct *task)
void gcs_set_el0_mode(struct task_struct *task);
void gcs_free(struct task_struct *task);
void gcs_preserve_current_state(void);
-unsigned long gcs_alloc_thread_stack(struct task_struct *tsk,
- const struct kernel_clone_args *args);
+int gcs_alloc_thread_stack(struct task_struct *tsk,
+ const struct kernel_clone_args *args);
static inline int gcs_check_locked(struct task_struct *task,
unsigned long new_val)
@@ -91,8 +91,8 @@ static inline bool task_gcs_el0_enabled(struct task_struct *task)
static inline void gcs_set_el0_mode(struct task_struct *task) { }
static inline void gcs_free(struct task_struct *task) { }
static inline void gcs_preserve_current_state(void) { }
-static inline unsigned long gcs_alloc_thread_stack(struct task_struct *tsk,
- const struct kernel_clone_args *args)
+static inline int gcs_alloc_thread_stack(struct task_struct *tsk,
+ const struct kernel_clone_args *args)
{
return -ENOTSUPP;
}
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 5954cec19660..630fbbf95019 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -299,7 +299,7 @@ static void flush_gcs(void)
static int copy_thread_gcs(struct task_struct *p,
const struct kernel_clone_args *args)
{
- unsigned long gcs;
+ int ret;
if (!system_supports_gcs())
return 0;
@@ -307,9 +307,9 @@ static int copy_thread_gcs(struct task_struct *p,
p->thread.gcs_base = 0;
p->thread.gcs_size = 0;
- gcs = gcs_alloc_thread_stack(p, args);
- if (IS_ERR_VALUE(gcs))
- return PTR_ERR((void *)gcs);
+ ret = gcs_alloc_thread_stack(p, args);
+ if (ret != 0)
+ return ret;
p->thread.gcs_el0_mode = current->thread.gcs_el0_mode;
p->thread.gcs_el0_locked = current->thread.gcs_el0_locked;
diff --git a/arch/arm64/mm/gcs.c b/arch/arm64/mm/gcs.c
index 5c46ec527b1c..1f633a482558 100644
--- a/arch/arm64/mm/gcs.c
+++ b/arch/arm64/mm/gcs.c
@@ -38,8 +38,8 @@ static unsigned long gcs_size(unsigned long size)
return max(PAGE_SIZE, size);
}
-unsigned long gcs_alloc_thread_stack(struct task_struct *tsk,
- const struct kernel_clone_args *args)
+int gcs_alloc_thread_stack(struct task_struct *tsk,
+ const struct kernel_clone_args *args)
{
unsigned long addr, size;
@@ -59,13 +59,13 @@ unsigned long gcs_alloc_thread_stack(struct task_struct *tsk,
size = gcs_size(size);
addr = alloc_gcs(0, size);
if (IS_ERR_VALUE(addr))
- return addr;
+ return PTR_ERR((void *)addr);
tsk->thread.gcs_base = addr;
tsk->thread.gcs_size = size;
tsk->thread.gcspr_el0 = addr + size - sizeof(u64);
- return addr;
+ return 0;
}
SYSCALL_DEFINE3(map_shadow_stack, unsigned long, addr, unsigned long, size, unsigned int, flags)
--
2.39.5
^ permalink raw reply related
* [PATCH v18 0/8] fork: Support shadow stacks in clone3()
From: Mark Brown @ 2025-07-02 10:39 UTC (permalink / raw)
To: Rick P. Edgecombe, Deepak Gupta, Szabolcs Nagy, H.J. Lu,
Florian Weimer, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Dave Hansen, x86, H. Peter Anvin, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Valentin Schneider, Christian Brauner, Shuah Khan
Cc: linux-kernel, Catalin Marinas, Will Deacon, jannh, bsegall,
Andrew Morton, Yury Khrustalev, Wilco Dijkstra, linux-kselftest,
linux-api, Mark Brown, Kees Cook, Kees Cook, Shuah Khan
The kernel has recently added support for shadow stacks, currently
x86 only using their CET feature but both arm64 and RISC-V have
equivalent features (GCS and Zicfiss respectively), I am actively
working on GCS[1]. With shadow stacks the hardware maintains an
additional stack containing only the return addresses for branch
instructions which is not generally writeable by userspace and ensures
that any returns are to the recorded addresses. This provides some
protection against ROP attacks and making it easier to collect call
stacks. These shadow stacks are allocated in the address space of the
userspace process.
Our API for shadow stacks does not currently offer userspace any
flexiblity for managing the allocation of shadow stacks for newly
created threads, instead the kernel allocates a new shadow stack with
the same size as the normal stack whenever a thread is created with the
feature enabled. The stacks allocated in this way are freed by the
kernel when the thread exits or shadow stacks are disabled for the
thread. This lack of flexibility and control isn't ideal, in the vast
majority of cases the shadow stack will be over allocated and the
implicit allocation and deallocation is not consistent with other
interfaces. As far as I can tell the interface is done in this manner
mainly because the shadow stack patches were in development since before
clone3() was implemented.
Since clone3() is readily extensible let's add support for specifying a
shadow stack when creating a new thread or process, keeping the current
implicit allocation behaviour if one is not specified either with
clone3() or through the use of clone(). The user must provide a shadow
stack pointer, this must point to memory mapped for use as a shadow
stackby map_shadow_stack() with an architecture specified shadow stack
token at the top of the stack.
Yuri Khrustalev has raised questions from the libc side regarding
discoverability of extended clone3() structure sizes[2], this seems like
a general issue with clone3(). There was a suggestion to add a hwcap on
arm64 which isn't ideal but is doable there, though architecture
specific mechanisms would also be needed for x86 (and RISC-V if it's
support gets merged before this does). The idea has, however, had
strong pushback from the architecture maintainers and it is possible to
detect support for this in clone3() by attempting a call with a
misaligned shadow stack pointer specified so no hwcap has been added.
[1] https://lore.kernel.org/linux-arm-kernel/20241001-arm64-gcs-v13-0-222b78d87eee@kernel.org/T/#mc58f97f27461749ccf400ebabf6f9f937116a86b
[2] https://lore.kernel.org/r/aCs65ccRQtJBnZ_5@arm.com
Signed-off-by: Mark Brown <broonie@kernel.org>
---
Changes in v18:
- Rebase onto v6.16-rc3.
- Thanks to pointers from Yuri Khrustalev this version has been tested
on x86 so I have removed the RFT tag.
- Clarify clone3_shadow_stack_valid() comment about the Kconfig check.
- Remove redundant GCSB DSYNCs in arm64 code.
- Fix token validation on x86.
- Link to v17: https://lore.kernel.org/r/20250609-clone3-shadow-stack-v17-0-8840ed97ff6f@kernel.org
Changes in v17:
- Rebase onto v6.16-rc1.
- Link to v16: https://lore.kernel.org/r/20250416-clone3-shadow-stack-v16-0-2ffc9ca3917b@kernel.org
Changes in v16:
- Rebase onto v6.15-rc2.
- Roll in fixes from x86 testing from Rick Edgecombe.
- Rework so that the argument is shadow_stack_token.
- Link to v15: https://lore.kernel.org/r/20250408-clone3-shadow-stack-v15-0-3fa245c6e3be@kernel.org
Changes in v15:
- Rebase onto v6.15-rc1.
- Link to v14: https://lore.kernel.org/r/20250206-clone3-shadow-stack-v14-0-805b53af73b9@kernel.org
Changes in v14:
- Rebase onto v6.14-rc1.
- Link to v13: https://lore.kernel.org/r/20241203-clone3-shadow-stack-v13-0-93b89a81a5ed@kernel.org
Changes in v13:
- Rebase onto v6.13-rc1.
- Link to v12: https://lore.kernel.org/r/20241031-clone3-shadow-stack-v12-0-7183eb8bee17@kernel.org
Changes in v12:
- Add the regular prctl() to the userspace API document since arm64
support is queued in -next.
- Link to v11: https://lore.kernel.org/r/20241005-clone3-shadow-stack-v11-0-2a6a2bd6d651@kernel.org
Changes in v11:
- Rebase onto arm64 for-next/gcs, which is based on v6.12-rc1, and
integrate arm64 support.
- Rework the interface to specify a shadow stack pointer rather than a
base and size like we do for the regular stack.
- Link to v10: https://lore.kernel.org/r/20240821-clone3-shadow-stack-v10-0-06e8797b9445@kernel.org
Changes in v10:
- Integrate fixes & improvements for the x86 implementation from Rick
Edgecombe.
- Require that the shadow stack be VM_WRITE.
- Require that the shadow stack base and size be sizeof(void *) aligned.
- Clean up trailing newline.
- Link to v9: https://lore.kernel.org/r/20240819-clone3-shadow-stack-v9-0-962d74f99464@kernel.org
Changes in v9:
- Pull token validation earlier and report problems with an error return
to parent rather than signal delivery to the child.
- Verify that the top of the supplied shadow stack is VM_SHADOW_STACK.
- Rework token validation to only do the page mapping once.
- Drop no longer needed support for testing for signals in selftest.
- Fix typo in comments.
- Link to v8: https://lore.kernel.org/r/20240808-clone3-shadow-stack-v8-0-0acf37caf14c@kernel.org
Changes in v8:
- Fix token verification with user specified shadow stack.
- Don't track user managed shadow stacks for child processes.
- Link to v7: https://lore.kernel.org/r/20240731-clone3-shadow-stack-v7-0-a9532eebfb1d@kernel.org
Changes in v7:
- Rebase onto v6.11-rc1.
- Typo fixes.
- Link to v6: https://lore.kernel.org/r/20240623-clone3-shadow-stack-v6-0-9ee7783b1fb9@kernel.org
Changes in v6:
- Rebase onto v6.10-rc3.
- Ensure we don't try to free the parent shadow stack in error paths of
x86 arch code.
- Spelling fixes in userspace API document.
- Additional cleanups and improvements to the clone3() tests to support
the shadow stack tests.
- Link to v5: https://lore.kernel.org/r/20240203-clone3-shadow-stack-v5-0-322c69598e4b@kernel.org
Changes in v5:
- Rebase onto v6.8-rc2.
- Rework ABI to have the user allocate the shadow stack memory with
map_shadow_stack() and a token.
- Force inlining of the x86 shadow stack enablement.
- Move shadow stack enablement out into a shared header for reuse by
other tests.
- Link to v4: https://lore.kernel.org/r/20231128-clone3-shadow-stack-v4-0-8b28ffe4f676@kernel.org
Changes in v4:
- Formatting changes.
- Use a define for minimum shadow stack size and move some basic
validation to fork.c.
- Link to v3: https://lore.kernel.org/r/20231120-clone3-shadow-stack-v3-0-a7b8ed3e2acc@kernel.org
Changes in v3:
- Rebase onto v6.7-rc2.
- Remove stale shadow_stack in internal kargs.
- If a shadow stack is specified unconditionally use it regardless of
CLONE_ parameters.
- Force enable shadow stacks in the selftest.
- Update changelogs for RISC-V feature rename.
- Link to v2: https://lore.kernel.org/r/20231114-clone3-shadow-stack-v2-0-b613f8681155@kernel.org
Changes in v2:
- Rebase onto v6.7-rc1.
- Remove ability to provide preallocated shadow stack, just specify the
desired size.
- Link to v1: https://lore.kernel.org/r/20231023-clone3-shadow-stack-v1-0-d867d0b5d4d0@kernel.org
---
Mark Brown (8):
arm64/gcs: Return a success value from gcs_alloc_thread_stack()
Documentation: userspace-api: Add shadow stack API documentation
selftests: Provide helper header for shadow stack testing
fork: Add shadow stack support to clone3()
selftests/clone3: Remove redundant flushes of output streams
selftests/clone3: Factor more of main loop into test_clone3()
selftests/clone3: Allow tests to flag if -E2BIG is a valid error code
selftests/clone3: Test shadow stack support
Documentation/userspace-api/index.rst | 1 +
Documentation/userspace-api/shadow_stack.rst | 44 +++++
arch/arm64/include/asm/gcs.h | 8 +-
arch/arm64/kernel/process.c | 8 +-
arch/arm64/mm/gcs.c | 55 +++++-
arch/x86/include/asm/shstk.h | 11 +-
arch/x86/kernel/process.c | 2 +-
arch/x86/kernel/shstk.c | 53 ++++-
include/asm-generic/cacheflush.h | 11 ++
include/linux/sched/task.h | 17 ++
include/uapi/linux/sched.h | 9 +-
kernel/fork.c | 93 +++++++--
tools/testing/selftests/clone3/clone3.c | 226 ++++++++++++++++++----
tools/testing/selftests/clone3/clone3_selftests.h | 65 ++++++-
tools/testing/selftests/ksft_shstk.h | 98 ++++++++++
15 files changed, 620 insertions(+), 81 deletions(-)
---
base-commit: 86731a2a651e58953fc949573895f2fa6d456841
change-id: 20231019-clone3-shadow-stack-15d40d2bf536
Best regards,
--
Mark Brown <broonie@kernel.org>
^ permalink raw reply
* Re: [PATCH v6 5/6] fs: prepare for extending file_get/setattr()
From: Amir Goldstein @ 2025-07-02 9:48 UTC (permalink / raw)
To: Pali Rohár
Cc: Darrick J. Wong, Andrey Albershteyn, Arnd Bergmann,
Casey Schaufler, Christian Brauner, Jan Kara, Paul Moore,
linux-api, linux-fsdevel, linux-kernel, linux-xfs, selinux,
Andrey Albershteyn
In-Reply-To: <CAOQ4uxjZWGz2bqen4F+fkQqZYQjKyufFVky4tOTnwng4D5G4nQ@mail.gmail.com>
On Wed, Jul 2, 2025 at 9:03 AM Amir Goldstein <amir73il@gmail.com> wrote:
>
> On Tue, Jul 1, 2025 at 9:54 PM Pali Rohár <pali@kernel.org> wrote:
> >
> > On Tuesday 01 July 2025 12:40:02 Darrick J. Wong wrote:
> > > On Tue, Jul 01, 2025 at 09:27:38PM +0200, Amir Goldstein wrote:
> > > > On Tue, Jul 1, 2025 at 8:31 PM Darrick J. Wong <djwong@kernel.org> wrote:
> > > > >
> > > > > On Mon, Jun 30, 2025 at 06:20:15PM +0200, Andrey Albershteyn wrote:
> > > > > > From: Amir Goldstein <amir73il@gmail.com>
> > > > > >
> > > > > > We intend to add support for more xflags to selective filesystems and
> > > > > > We cannot rely on copy_struct_from_user() to detect this extension.
> > > > > >
> > > > > > In preparation of extending the API, do not allow setting xflags unknown
> > > > > > by this kernel version.
> > > > > >
> > > > > > Also do not pass the read-only flags and read-only field fsx_nextents to
> > > > > > filesystem.
> > > > > >
> > > > > > These changes should not affect existing chattr programs that use the
> > > > > > ioctl to get fsxattr before setting the new values.
> > > > > >
> > > > > > Link: https://lore.kernel.org/linux-fsdevel/20250216164029.20673-4-pali@kernel.org/
> > > > > > Cc: Pali Rohár <pali@kernel.org>
> > > > > > Cc: Andrey Albershteyn <aalbersh@redhat.com>
> > > > > > Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> > > > > > Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
> > > > > > ---
> > > > > > fs/file_attr.c | 8 +++++++-
> > > > > > include/linux/fileattr.h | 20 ++++++++++++++++++++
> > > > > > 2 files changed, 27 insertions(+), 1 deletion(-)
> > > > > >
> > > > > > diff --git a/fs/file_attr.c b/fs/file_attr.c
> > > > > > index 4e85fa00c092..62f08872d4ad 100644
> > > > > > --- a/fs/file_attr.c
> > > > > > +++ b/fs/file_attr.c
> > > > > > @@ -99,9 +99,10 @@ EXPORT_SYMBOL(vfs_fileattr_get);
> > > > > > int copy_fsxattr_to_user(const struct fileattr *fa, struct fsxattr __user *ufa)
> > > > > > {
> > > > > > struct fsxattr xfa;
> > > > > > + __u32 mask = FS_XFLAGS_MASK;
> > > > > >
> > > > > > memset(&xfa, 0, sizeof(xfa));
> > > > > > - xfa.fsx_xflags = fa->fsx_xflags;
> > > > > > + xfa.fsx_xflags = fa->fsx_xflags & mask;
> > > > >
> > > > > I wonder, should it be an error if a filesystem sets an fsx_xflags bit
> > > > > outside of FS_XFLAGS_MASK? I guess that's one way to prevent
> > > > > filesystems from overriding the VFS bits. ;)
> > > >
> > > > I think Pali has a plan on how to ensure that later
> > > > when the mask is provided via the API.
> > > >
> > > > >
> > > > > Though couldn't that be:
> > > > >
> > > > > xfa.fsx_xflags = fa->fsx_xflags & FS_XFLAGS_MASK;
> > > > >
> > > > > instead? And same below?
> > > > >
> > > >
> > > > Indeed. There is a reason for the var, because the next series
> > > > by Pali will use a user provided mask, which defaults to FS_XFLAGS_MASK,
> > > > so I left it this way.
> > > >
> > > > I don't see a problem with it keeping as is, but if it bothers you
> > > > I guess we can re-add the var later.
> > >
> > > Nah, it doesn't bother me that much.
> > >
> > > > > > xfa.fsx_extsize = fa->fsx_extsize;
> > > > > > xfa.fsx_nextents = fa->fsx_nextents;
> > > > > > xfa.fsx_projid = fa->fsx_projid;
> > > > > > @@ -118,11 +119,16 @@ static int copy_fsxattr_from_user(struct fileattr *fa,
> > > > > > struct fsxattr __user *ufa)
> > > > > > {
> > > > > > struct fsxattr xfa;
> > > > > > + __u32 mask = FS_XFLAGS_MASK;
> > > > > >
> > > > > > if (copy_from_user(&xfa, ufa, sizeof(xfa)))
> > > > > > return -EFAULT;
> > > > > >
> > > > > > + if (xfa.fsx_xflags & ~mask)
> > > > > > + return -EINVAL;
> > > > >
> > > > > I wonder if you want EOPNOTSUPP here? We don't know how to support
> > > > > unknown xflags. OTOH if you all have beaten this to death while I was
> > > > > out then don't start another round just for me. :P
> > > >
> > > > We have beaten this API almost to death for sure ;)
> > > > I don't remember if we discussed this specific aspect,
> > > > but I am personally in favor of
> > > > EOPNOTSUPP := the fs does not support the set/get operation
> > > > EINVAL := some flags provided as value is invalid
> > > >
> > > > For example, if the get API provides you with a mask of the
> > > > valid flags that you can set, if you try to set flags outside of
> > > > that mask you get EINVAL.
> > > >
> > > > That's my interpretation, but I agree that EOPNOTSUPP can also
> > > > make sense in this situation.
> > >
> > > <nod> I think I'd rather EOPNOTSUPP for "bits are set that the kernel
> > > doesn't recognize" and EINVAL (or maybe something else like
> > > EPROTONOSUPPORT) for "fs driver will not let you change this bit".
> > > At least for the syscall interface; we probably have to flatten that to
> > > EOPNOTSUPP for both legacy ioctls.
>
> Given the precedents of returning EOPNOTSUPP in xfs_fileattr_set()
> and ext4_ioctl_setflags() for flags that cannot be set, I agree.
>
Wait, I misparsed what you wrote, so I think I "agreed" only to the
first part of your suggestion.
My claim is that unlike the xfs_has_v3inodes() check in
xfs_ioctl_setattr_xflags(),
ext4/f2fs etc return EOPNOTSUPP for various flags depending on supported fs
features (e.g. casefold,dax,encryption), so I think it will be hard to
impose a strict rule
where "fs does not support the feature" returns EINVAL in the syscalls API.
Therefore, I propose to change the code in this patch to
return EOPNOTSUPP for flags that kernel does not support
and with coming changes from Pali, it will also return the same
EOPNOTSUPP for flags that the fs instance does not support.
Christian,
Can you please amend the return value in the following chunk:
@@ -119,11 +120,16 @@ static int copy_fsxattr_from_user(struct fileattr *fa,
struct fsxattr __user *ufa)
{
struct fsxattr xfa;
+ __u32 mask = FS_XFLAGS_MASK;
if (copy_from_user(&xfa, ufa, sizeof(xfa)))
return -EFAULT;
+ if (xfa.fsx_xflags & ~mask)
+ return -EOPNOTSUPP;
+
Thanks,
Amir.
^ permalink raw reply
* Re: [PATCH v6 6/6] fs: introduce file_getattr and file_setattr syscalls
From: Amir Goldstein @ 2025-07-02 9:13 UTC (permalink / raw)
To: Christian Brauner
Cc: Andrey Albershteyn, Arnd Bergmann, Casey Schaufler, Jan Kara,
Pali Rohár, Paul Moore, linux-api, linux-fsdevel,
linux-kernel, linux-xfs, selinux, Andrey Albershteyn
In-Reply-To: <20250701-bauzaun-riskieren-595464ef81c4@brauner>
> > +/*
> > + * Variable size structure for file_[sg]et_attr().
> > + *
> > + * Note. This is alternative to the structure 'struct fileattr'/'struct fsxattr'.
> > + * As this structure is passed to/from userspace with its size, this can
> > + * be versioned based on the size.
> > + */
> > +struct fsx_fileattr {
> > + __u32 fsx_xflags; /* xflags field value (get/set) */
> > + __u32 fsx_extsize; /* extsize field value (get/set)*/
> > + __u32 fsx_nextents; /* nextents field value (get) */
> > + __u32 fsx_projid; /* project identifier (get/set) */
> > + __u32 fsx_cowextsize; /* CoW extsize field value (get/set) */
>
> This misses a:
>
> __u32 __spare;
>
> so there's no holes in the struct. :)
Adding __spare and not verifying that it is zeroed gets us to the
point that we are not able to replace __spare with a real field later.
I suggest to resolve this hole as Darrick and Pali suggested by making it
__u64 fsx_xflags
w.r.t Darrick's comment, I kind of like it that the name for the UAPI
struct (fsxattr)
differs from the name of the kernel internal representation (fileattr), but
I agree that fsx_fileattr does not give a good hint on what it is.
I think that renaming struct fsx_fileattr to struct fsxattr64 along
with changing the
width of fsx_xflags will help reduce the confusion of users.
What do you guys think?
Thanks,
Amir.
^ permalink raw reply
* Re: [PATCH v6 2/6] lsm: introduce new hooks for setting/getting inode fsxattr
From: Andrey Albershteyn @ 2025-07-02 8:47 UTC (permalink / raw)
To: Darrick J. Wong
Cc: Amir Goldstein, Arnd Bergmann, Casey Schaufler, Christian Brauner,
Jan Kara, Pali Rohár, Paul Moore, linux-api, linux-fsdevel,
linux-kernel, linux-xfs, selinux, Andrey Albershteyn
In-Reply-To: <20250701181813.GN10009@frogsfrogsfrogs>
On 2025-07-01 11:18:13, Darrick J. Wong wrote:
> On Mon, Jun 30, 2025 at 06:20:12PM +0200, Andrey Albershteyn wrote:
> > Introduce new hooks for setting and getting filesystem extended
> > attributes on inode (FS_IOC_FSGETXATTR).
> >
> > Cc: selinux@vger.kernel.org
> > Cc: Paul Moore <paul@paul-moore.com>
> >
> > Acked-by: Paul Moore <paul@paul-moore.com>
> > Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
>
> I wonder, were FS_IOC_FS[GS]ETXATTR already covered by the
> security_file_ioctl hook?
looks like
> If so, will an out of date security policy
> on a 6.17 kernel now fail to check the new file_[gs]etattr syscalls?
Yeah, probably, not sure if policies can have 'don't allow unknown'
but this is probably will need to be updated in the policy
>
> Though AFAICT the future of managing these "extra" file attributes is
> the system call so it's probably appropriate to have an explicit
> callout to LSMs.
>
> Acked-by: "Darrick J. Wong" <djwong@kernel.org>
>
> --D
>
> > ---
> > fs/file_attr.c | 19 ++++++++++++++++---
> > include/linux/lsm_hook_defs.h | 2 ++
> > include/linux/security.h | 16 ++++++++++++++++
> > security/security.c | 30 ++++++++++++++++++++++++++++++
> > 4 files changed, 64 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/file_attr.c b/fs/file_attr.c
> > index 2910b7047721..be62d97cc444 100644
> > --- a/fs/file_attr.c
> > +++ b/fs/file_attr.c
> > @@ -76,10 +76,15 @@ EXPORT_SYMBOL(fileattr_fill_flags);
> > int vfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
> > {
> > struct inode *inode = d_inode(dentry);
> > + int error;
> >
> > if (!inode->i_op->fileattr_get)
> > return -ENOIOCTLCMD;
> >
> > + error = security_inode_file_getattr(dentry, fa);
> > + if (error)
> > + return error;
> > +
> > return inode->i_op->fileattr_get(dentry, fa);
> > }
> > EXPORT_SYMBOL(vfs_fileattr_get);
> > @@ -242,12 +247,20 @@ int vfs_fileattr_set(struct mnt_idmap *idmap, struct dentry *dentry,
> > } else {
> > fa->flags |= old_ma.flags & ~FS_COMMON_FL;
> > }
> > +
> > err = fileattr_set_prepare(inode, &old_ma, fa);
> > - if (!err)
> > - err = inode->i_op->fileattr_set(idmap, dentry, fa);
> > + if (err)
> > + goto out;
> > + err = security_inode_file_setattr(dentry, fa);
> > + if (err)
> > + goto out;
> > + err = inode->i_op->fileattr_set(idmap, dentry, fa);
> > + if (err)
> > + goto out;
> > }
> > +
> > +out:
> > inode_unlock(inode);
> > -
> > return err;
> > }
> > EXPORT_SYMBOL(vfs_fileattr_set);
> > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> > index bf3bbac4e02a..9600a4350e79 100644
> > --- a/include/linux/lsm_hook_defs.h
> > +++ b/include/linux/lsm_hook_defs.h
> > @@ -157,6 +157,8 @@ LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
> > struct dentry *dentry, const char *name)
> > LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry,
> > const char *name)
> > +LSM_HOOK(int, 0, inode_file_setattr, struct dentry *dentry, struct fileattr *fa)
> > +LSM_HOOK(int, 0, inode_file_getattr, struct dentry *dentry, struct fileattr *fa)
> > LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap,
> > struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
> > LSM_HOOK(void, LSM_RET_VOID, inode_post_set_acl, struct dentry *dentry,
> > diff --git a/include/linux/security.h b/include/linux/security.h
> > index dba349629229..9ed0d0e0c81f 100644
> > --- a/include/linux/security.h
> > +++ b/include/linux/security.h
> > @@ -451,6 +451,10 @@ int security_inode_listxattr(struct dentry *dentry);
> > int security_inode_removexattr(struct mnt_idmap *idmap,
> > struct dentry *dentry, const char *name);
> > void security_inode_post_removexattr(struct dentry *dentry, const char *name);
> > +int security_inode_file_setattr(struct dentry *dentry,
> > + struct fileattr *fa);
> > +int security_inode_file_getattr(struct dentry *dentry,
> > + struct fileattr *fa);
> > int security_inode_need_killpriv(struct dentry *dentry);
> > int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry);
> > int security_inode_getsecurity(struct mnt_idmap *idmap,
> > @@ -1052,6 +1056,18 @@ static inline void security_inode_post_removexattr(struct dentry *dentry,
> > const char *name)
> > { }
> >
> > +static inline int security_inode_file_setattr(struct dentry *dentry,
> > + struct fileattr *fa)
> > +{
> > + return 0;
> > +}
> > +
> > +static inline int security_inode_file_getattr(struct dentry *dentry,
> > + struct fileattr *fa)
> > +{
> > + return 0;
> > +}
> > +
> > static inline int security_inode_need_killpriv(struct dentry *dentry)
> > {
> > return cap_inode_need_killpriv(dentry);
> > diff --git a/security/security.c b/security/security.c
> > index 596d41818577..711b4de40b8d 100644
> > --- a/security/security.c
> > +++ b/security/security.c
> > @@ -2622,6 +2622,36 @@ void security_inode_post_removexattr(struct dentry *dentry, const char *name)
> > call_void_hook(inode_post_removexattr, dentry, name);
> > }
> >
> > +/**
> > + * security_inode_file_setattr() - check if setting fsxattr is allowed
> > + * @dentry: file to set filesystem extended attributes on
> > + * @fa: extended attributes to set on the inode
> > + *
> > + * Called when file_setattr() syscall or FS_IOC_FSSETXATTR ioctl() is called on
> > + * inode
> > + *
> > + * Return: Returns 0 if permission is granted.
> > + */
> > +int security_inode_file_setattr(struct dentry *dentry, struct fileattr *fa)
> > +{
> > + return call_int_hook(inode_file_setattr, dentry, fa);
> > +}
> > +
> > +/**
> > + * security_inode_file_getattr() - check if retrieving fsxattr is allowed
> > + * @dentry: file to retrieve filesystem extended attributes from
> > + * @fa: extended attributes to get
> > + *
> > + * Called when file_getattr() syscall or FS_IOC_FSGETXATTR ioctl() is called on
> > + * inode
> > + *
> > + * Return: Returns 0 if permission is granted.
> > + */
> > +int security_inode_file_getattr(struct dentry *dentry, struct fileattr *fa)
> > +{
> > + return call_int_hook(inode_file_getattr, dentry, fa);
> > +}
> > +
> > /**
> > * security_inode_need_killpriv() - Check if security_inode_killpriv() required
> > * @dentry: associated dentry
> >
> > --
> > 2.47.2
> >
> >
>
--
- Andrey
^ permalink raw reply
* Re: [PATCH v6 5/6] fs: prepare for extending file_get/setattr()
From: Amir Goldstein @ 2025-07-02 7:03 UTC (permalink / raw)
To: Pali Rohár
Cc: Darrick J. Wong, Andrey Albershteyn, Arnd Bergmann,
Casey Schaufler, Christian Brauner, Jan Kara, Paul Moore,
linux-api, linux-fsdevel, linux-kernel, linux-xfs, selinux,
Andrey Albershteyn
In-Reply-To: <20250701195405.xf27mjknu5bnunue@pali>
On Tue, Jul 1, 2025 at 9:54 PM Pali Rohár <pali@kernel.org> wrote:
>
> On Tuesday 01 July 2025 12:40:02 Darrick J. Wong wrote:
> > On Tue, Jul 01, 2025 at 09:27:38PM +0200, Amir Goldstein wrote:
> > > On Tue, Jul 1, 2025 at 8:31 PM Darrick J. Wong <djwong@kernel.org> wrote:
> > > >
> > > > On Mon, Jun 30, 2025 at 06:20:15PM +0200, Andrey Albershteyn wrote:
> > > > > From: Amir Goldstein <amir73il@gmail.com>
> > > > >
> > > > > We intend to add support for more xflags to selective filesystems and
> > > > > We cannot rely on copy_struct_from_user() to detect this extension.
> > > > >
> > > > > In preparation of extending the API, do not allow setting xflags unknown
> > > > > by this kernel version.
> > > > >
> > > > > Also do not pass the read-only flags and read-only field fsx_nextents to
> > > > > filesystem.
> > > > >
> > > > > These changes should not affect existing chattr programs that use the
> > > > > ioctl to get fsxattr before setting the new values.
> > > > >
> > > > > Link: https://lore.kernel.org/linux-fsdevel/20250216164029.20673-4-pali@kernel.org/
> > > > > Cc: Pali Rohár <pali@kernel.org>
> > > > > Cc: Andrey Albershteyn <aalbersh@redhat.com>
> > > > > Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> > > > > Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
> > > > > ---
> > > > > fs/file_attr.c | 8 +++++++-
> > > > > include/linux/fileattr.h | 20 ++++++++++++++++++++
> > > > > 2 files changed, 27 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/fs/file_attr.c b/fs/file_attr.c
> > > > > index 4e85fa00c092..62f08872d4ad 100644
> > > > > --- a/fs/file_attr.c
> > > > > +++ b/fs/file_attr.c
> > > > > @@ -99,9 +99,10 @@ EXPORT_SYMBOL(vfs_fileattr_get);
> > > > > int copy_fsxattr_to_user(const struct fileattr *fa, struct fsxattr __user *ufa)
> > > > > {
> > > > > struct fsxattr xfa;
> > > > > + __u32 mask = FS_XFLAGS_MASK;
> > > > >
> > > > > memset(&xfa, 0, sizeof(xfa));
> > > > > - xfa.fsx_xflags = fa->fsx_xflags;
> > > > > + xfa.fsx_xflags = fa->fsx_xflags & mask;
> > > >
> > > > I wonder, should it be an error if a filesystem sets an fsx_xflags bit
> > > > outside of FS_XFLAGS_MASK? I guess that's one way to prevent
> > > > filesystems from overriding the VFS bits. ;)
> > >
> > > I think Pali has a plan on how to ensure that later
> > > when the mask is provided via the API.
> > >
> > > >
> > > > Though couldn't that be:
> > > >
> > > > xfa.fsx_xflags = fa->fsx_xflags & FS_XFLAGS_MASK;
> > > >
> > > > instead? And same below?
> > > >
> > >
> > > Indeed. There is a reason for the var, because the next series
> > > by Pali will use a user provided mask, which defaults to FS_XFLAGS_MASK,
> > > so I left it this way.
> > >
> > > I don't see a problem with it keeping as is, but if it bothers you
> > > I guess we can re-add the var later.
> >
> > Nah, it doesn't bother me that much.
> >
> > > > > xfa.fsx_extsize = fa->fsx_extsize;
> > > > > xfa.fsx_nextents = fa->fsx_nextents;
> > > > > xfa.fsx_projid = fa->fsx_projid;
> > > > > @@ -118,11 +119,16 @@ static int copy_fsxattr_from_user(struct fileattr *fa,
> > > > > struct fsxattr __user *ufa)
> > > > > {
> > > > > struct fsxattr xfa;
> > > > > + __u32 mask = FS_XFLAGS_MASK;
> > > > >
> > > > > if (copy_from_user(&xfa, ufa, sizeof(xfa)))
> > > > > return -EFAULT;
> > > > >
> > > > > + if (xfa.fsx_xflags & ~mask)
> > > > > + return -EINVAL;
> > > >
> > > > I wonder if you want EOPNOTSUPP here? We don't know how to support
> > > > unknown xflags. OTOH if you all have beaten this to death while I was
> > > > out then don't start another round just for me. :P
> > >
> > > We have beaten this API almost to death for sure ;)
> > > I don't remember if we discussed this specific aspect,
> > > but I am personally in favor of
> > > EOPNOTSUPP := the fs does not support the set/get operation
> > > EINVAL := some flags provided as value is invalid
> > >
> > > For example, if the get API provides you with a mask of the
> > > valid flags that you can set, if you try to set flags outside of
> > > that mask you get EINVAL.
> > >
> > > That's my interpretation, but I agree that EOPNOTSUPP can also
> > > make sense in this situation.
> >
> > <nod> I think I'd rather EOPNOTSUPP for "bits are set that the kernel
> > doesn't recognize" and EINVAL (or maybe something else like
> > EPROTONOSUPPORT) for "fs driver will not let you change this bit".
> > At least for the syscall interface; we probably have to flatten that to
> > EOPNOTSUPP for both legacy ioctls.
Given the precedents of returning EOPNOTSUPP in xfs_fileattr_set()
and ext4_ioctl_setflags() for flags that cannot be set, I agree.
>
> ... and this starting to be complicated if the "fs driver" is network
> based (as fs driver can support, but remote server not). See also:
> https://lore.kernel.org/linux-fsdevel/20241224160535.pi6nazpugqkhvfns@pali/t/#u
>
> For backup/restore application it would be very useful to distinguish between:
> - "kernel does not support flag X"
> - "target filesystem does not support flag X"
> - "wrong structure was passed / syscall incorrectly called"
>
> third option is bug in application - fatal error. second option is just
> a warning for user (sorry, we cannot set NEW FEATURE on FAT32, but if
> you would do restore to other fs, it is supported). and first option
> happens when you run new application on older kernel version, it is an
> recoverable error (or warning to user, but with more important level
> then second option as switching to different FS would not help).
>
> Could we return different errnos for these 3 situations?
That would be nice, but actually according to your plan
the get API returns the mask of flags supported by the filesystem
(on that specific object even), so userspace in fact has a way to
distinguish between the first two EOPNOTSUPP cases.
Thanks,
Amir.
^ permalink raw reply
* Re: [RFC v2 01/22] kernel/api: introduce kernel API specification framework
From: Sasha Levin @ 2025-07-01 22:16 UTC (permalink / raw)
To: Jonathan Corbet
Cc: Mauro Carvalho Chehab, linux-kernel, linux-doc, linux-api,
workflows, tools, Kate Stewart, Gabriele Paoloni, Chuck Wolber
In-Reply-To: <87v7obpoxn.fsf@trenco.lwn.net>
On Tue, Jul 01, 2025 at 03:43:32PM -0600, Jonathan Corbet wrote:
>Sasha Levin <sashal@kernel.org> writes:
>
>> So I have a proof of concept which during the build process creates
>> .apispec.h which are generated from kerneldoc and contain macros
>> identical to the ones in my RFC.
>>
>> Here's an example of sys_mlock() spec:
>
>So I'm getting ahead of the game, but I have to ask some questions...
>
>> /**
>> * sys_mlock - Lock pages in memory
>> * @start: Starting address of memory range to lock
>> * @len: Length of memory range to lock in bytes
>> *
>> * Locks pages in the specified address range into RAM, preventing them from
>> * being paged to swap. Requires CAP_IPC_LOCK capability or RLIMIT_MEMLOCK
>> * resource limit.
>> *
>> * long-desc: Locks pages in the specified address range into RAM, preventing
>> * them from being paged to swap. Requires CAP_IPC_LOCK capability
>> * or RLIMIT_MEMLOCK resource limit.
>
>Why duplicate the long description?
Will fix.
>> * context-flags: KAPI_CTX_PROCESS | KAPI_CTX_SLEEPABLE
>> * param-type: start, KAPI_TYPE_UINT
>
>This is something I wondered before; rather than a bunch of lengthy
>KAPI_* symbols, why not just say __u64 (or some other familiar type)
>here?
I think it gets tricky when we got to more complex types. For example,
how do we represent a FD or a (struct sockaddr *)?
With macros, KAPI_TYPE_FD or KAPI_TYPE_SOCKADDR make sense, but
__sockaddr will be a bit confusing (I think).
>> * param-flags: start, KAPI_PARAM_IN
>> * param-constraint-type: start, KAPI_CONSTRAINT_NONE
>> * param-constraint: start, Rounded down to page boundary
>> * param-type: len, KAPI_TYPE_UINT
>> * param-flags: len, KAPI_PARAM_IN
>> * param-constraint-type: len, KAPI_CONSTRAINT_RANGE
>> * param-range: len, 0, LONG_MAX
>> * param-constraint: len, Rounded up to page boundary
>> * return-type: KAPI_TYPE_INT
>> * return-check-type: KAPI_RETURN_ERROR_CHECK
>> * return-success: 0
>> * error-code: -ENOMEM, ENOMEM, Address range issue,
>> * Some of the specified range is not mapped, has unmapped gaps,
>> * or the lock would cause the number of mapped regions to exceed the limit.
>> * error-code: -EPERM, EPERM, Insufficient privileges,
>> * The caller is not privileged (no CAP_IPC_LOCK) and RLIMIT_MEMLOCK is 0.
>> * error-code: -EINVAL, EINVAL, Address overflow,
>> * The result of the addition start+len was less than start (arithmetic overflow).
>> * error-code: -EAGAIN, EAGAIN, Some or all memory could not be locked,
>> * Some or all of the specified address range could not be locked.
>> * error-code: -EINTR, EINTR, Interrupted by signal,
>> * The operation was interrupted by a fatal signal before completion.
>> * error-code: -EFAULT, EFAULT, Bad address,
>> * The specified address range contains invalid addresses that cannot be accessed.
>> * since-version: 2.0
>> * lock: mmap_lock, KAPI_LOCK_RWLOCK
>> * lock-acquired: true
>> * lock-released: true
>> * lock-desc: Process memory map write lock
>> * signal: FATAL
>> * signal-direction: KAPI_SIGNAL_RECEIVE
>> * signal-action: KAPI_SIGNAL_ACTION_RETURN
>> * signal-condition: Fatal signal pending
>> * signal-desc: Fatal signals (SIGKILL) can interrupt the operation at two points:
>> * when acquiring mmap_write_lock_killable() and during page population
>> * in __mm_populate(). Returns -EINTR. Non-fatal signals do NOT interrupt
>> * mlock - the operation continues even if SIGINT/SIGTERM are received.
>> * signal-error: -EINTR
>> * signal-timing: KAPI_SIGNAL_TIME_DURING
>> * signal-priority: 0
>> * signal-interruptible: yes
>> * signal-state-req: KAPI_SIGNAL_STATE_RUNNING
>> * examples: mlock(addr, 4096); // Lock one page
>> * mlock(addr, len); // Lock range of pages
>> * notes: Memory locks do not stack - multiple calls on the same range can be
>> * undone by a single munlock. Locks are not inherited by child processes.
>> * Pages are locked on whole page boundaries. Commonly used by real-time
>> * applications to prevent page faults during time-critical operations.
>> * Also used for security to prevent sensitive data (e.g., cryptographic keys)
>> * from being written to swap. Note: locked pages may still be saved to
>> * swap during system suspend/hibernate.
>> *
>> * Tagged addresses are automatically handled via untagged_addr(). The operation
>> * occurs in two phases: first VMAs are marked with VM_LOCKED, then pages are
>> * populated into memory. When checking RLIMIT_MEMLOCK, the kernel optimizes
>> * by recounting locked memory to avoid double-counting overlapping regions.
>> * side-effect: KAPI_EFFECT_MODIFY_STATE | KAPI_EFFECT_ALLOC_MEMORY, process memory, Locks pages into physical memory, preventing swapping, reversible=yes
>
>I hope the really long lines starting here aren't the intended way to go...:)
I guess that we have two options around more complex blocks like these.
One, the longer lines you've pointed out. They are indeed long and
difficult to read, but they present a relatively static and "not too
interesting" information which users are likely to gloss over.
The other one would look something like:
side-effect: KAPI_EFFECT_MODIFY_STATE
side-effect-type: KAPI_EFFECT_MODIFY_STATE
side-effect-target: mm->locked_vm
side-effect-description: Increases process locked memory counter
side-effect-reversible: yes
Which isn't as long, but it occupies a bunch of vertical real estate
while not being too interesting for most of the readers.
>> * side-effect: KAPI_EFFECT_MODIFY_STATE, mm->locked_vm, Increases process locked memory counter, reversible=yes
>> * side-effect: KAPI_EFFECT_ALLOC_MEMORY, physical pages, May allocate and populate page table entries, condition=Pages not already present, reversible=yes
>> * side-effect: KAPI_EFFECT_MODIFY_STATE | KAPI_EFFECT_ALLOC_MEMORY, page faults, Triggers page faults to bring pages into memory, condition=Pages not already resident
>> * side-effect: KAPI_EFFECT_MODIFY_STATE, VMA splitting, May split existing VMAs at lock boundaries, condition=Lock range partially overlaps existing VMA
>> * state-trans: memory pages, swappable, locked in RAM, Pages become non-swappable and pinned in physical memory
>> * state-trans: VMA flags, unlocked, VM_LOCKED set, Virtual memory area marked as locked
>> * capability: CAP_IPC_LOCK, KAPI_CAP_BYPASS_CHECK, CAP_IPC_LOCK capability
>> * capability-allows: Lock unlimited amount of memory (no RLIMIT_MEMLOCK enforcement)
>> * capability-without: Must respect RLIMIT_MEMLOCK resource limit
>> * capability-condition: Checked when RLIMIT_MEMLOCK is 0 or locking would exceed limit
>> * capability-priority: 0
>> * constraint: RLIMIT_MEMLOCK Resource Limit, The RLIMIT_MEMLOCK soft resource limit specifies the maximum bytes of memory that may be locked into RAM. Unprivileged processes are restricted to this limit. CAP_IPC_LOCK capability allows bypassing this limit entirely. The limit is enforced per-process, not per-user.
>> * constraint-expr: RLIMIT_MEMLOCK Resource Limit, locked_memory + request_size <= RLIMIT_MEMLOCK || CAP_IPC_LOCK
>> * constraint: Memory Pressure and OOM, Locking large amounts of memory can cause system-wide memory pressure and potentially trigger the OOM killer. The kernel does not prevent locking memory that would destabilize the system.
>> * constraint: Special Memory Areas, Some memory types cannot be locked or are silently skipped: VM_IO/VM_PFNMAP areas (device mappings) are skipped; Hugetlb pages are inherently pinned and skipped; DAX mappings are always present in memory and skipped; Secret memory (memfd_secret) mappings are skipped; VM_DROPPABLE memory cannot be locked and is skipped; Gate VMA (kernel entry point) is skipped; VM_LOCKED areas are already locked. These special areas are silently excluded without error.
>> *
>> * Context: Process context. May sleep. Takes mmap_lock for write.
>> *
>> * Return: 0 on success, negative error code on failure
>
>Both of these, of course, are much less informative versions of the data
>you have put up above; it would be nice to unify them somehow.
Ack
--
Thanks,
Sasha
^ permalink raw reply
* Re: [RFC v2 01/22] kernel/api: introduce kernel API specification framework
From: Jonathan Corbet @ 2025-07-01 21:43 UTC (permalink / raw)
To: Sasha Levin
Cc: Mauro Carvalho Chehab, linux-kernel, linux-doc, linux-api,
workflows, tools, Kate Stewart, Gabriele Paoloni, Chuck Wolber
In-Reply-To: <aGRKIuR6hgW0YLc_@lappy>
Sasha Levin <sashal@kernel.org> writes:
> So I have a proof of concept which during the build process creates
> .apispec.h which are generated from kerneldoc and contain macros
> identical to the ones in my RFC.
>
> Here's an example of sys_mlock() spec:
So I'm getting ahead of the game, but I have to ask some questions...
> /**
> * sys_mlock - Lock pages in memory
> * @start: Starting address of memory range to lock
> * @len: Length of memory range to lock in bytes
> *
> * Locks pages in the specified address range into RAM, preventing them from
> * being paged to swap. Requires CAP_IPC_LOCK capability or RLIMIT_MEMLOCK
> * resource limit.
> *
> * long-desc: Locks pages in the specified address range into RAM, preventing
> * them from being paged to swap. Requires CAP_IPC_LOCK capability
> * or RLIMIT_MEMLOCK resource limit.
Why duplicate the long description?
> * context-flags: KAPI_CTX_PROCESS | KAPI_CTX_SLEEPABLE
> * param-type: start, KAPI_TYPE_UINT
This is something I wondered before; rather than a bunch of lengthy
KAPI_* symbols, why not just say __u64 (or some other familiar type)
here?
> * param-flags: start, KAPI_PARAM_IN
> * param-constraint-type: start, KAPI_CONSTRAINT_NONE
> * param-constraint: start, Rounded down to page boundary
> * param-type: len, KAPI_TYPE_UINT
> * param-flags: len, KAPI_PARAM_IN
> * param-constraint-type: len, KAPI_CONSTRAINT_RANGE
> * param-range: len, 0, LONG_MAX
> * param-constraint: len, Rounded up to page boundary
> * return-type: KAPI_TYPE_INT
> * return-check-type: KAPI_RETURN_ERROR_CHECK
> * return-success: 0
> * error-code: -ENOMEM, ENOMEM, Address range issue,
> * Some of the specified range is not mapped, has unmapped gaps,
> * or the lock would cause the number of mapped regions to exceed the limit.
> * error-code: -EPERM, EPERM, Insufficient privileges,
> * The caller is not privileged (no CAP_IPC_LOCK) and RLIMIT_MEMLOCK is 0.
> * error-code: -EINVAL, EINVAL, Address overflow,
> * The result of the addition start+len was less than start (arithmetic overflow).
> * error-code: -EAGAIN, EAGAIN, Some or all memory could not be locked,
> * Some or all of the specified address range could not be locked.
> * error-code: -EINTR, EINTR, Interrupted by signal,
> * The operation was interrupted by a fatal signal before completion.
> * error-code: -EFAULT, EFAULT, Bad address,
> * The specified address range contains invalid addresses that cannot be accessed.
> * since-version: 2.0
> * lock: mmap_lock, KAPI_LOCK_RWLOCK
> * lock-acquired: true
> * lock-released: true
> * lock-desc: Process memory map write lock
> * signal: FATAL
> * signal-direction: KAPI_SIGNAL_RECEIVE
> * signal-action: KAPI_SIGNAL_ACTION_RETURN
> * signal-condition: Fatal signal pending
> * signal-desc: Fatal signals (SIGKILL) can interrupt the operation at two points:
> * when acquiring mmap_write_lock_killable() and during page population
> * in __mm_populate(). Returns -EINTR. Non-fatal signals do NOT interrupt
> * mlock - the operation continues even if SIGINT/SIGTERM are received.
> * signal-error: -EINTR
> * signal-timing: KAPI_SIGNAL_TIME_DURING
> * signal-priority: 0
> * signal-interruptible: yes
> * signal-state-req: KAPI_SIGNAL_STATE_RUNNING
> * examples: mlock(addr, 4096); // Lock one page
> * mlock(addr, len); // Lock range of pages
> * notes: Memory locks do not stack - multiple calls on the same range can be
> * undone by a single munlock. Locks are not inherited by child processes.
> * Pages are locked on whole page boundaries. Commonly used by real-time
> * applications to prevent page faults during time-critical operations.
> * Also used for security to prevent sensitive data (e.g., cryptographic keys)
> * from being written to swap. Note: locked pages may still be saved to
> * swap during system suspend/hibernate.
> *
> * Tagged addresses are automatically handled via untagged_addr(). The operation
> * occurs in two phases: first VMAs are marked with VM_LOCKED, then pages are
> * populated into memory. When checking RLIMIT_MEMLOCK, the kernel optimizes
> * by recounting locked memory to avoid double-counting overlapping regions.
> * side-effect: KAPI_EFFECT_MODIFY_STATE | KAPI_EFFECT_ALLOC_MEMORY, process memory, Locks pages into physical memory, preventing swapping, reversible=yes
I hope the really long lines starting here aren't the intended way to go...:)
> * side-effect: KAPI_EFFECT_MODIFY_STATE, mm->locked_vm, Increases process locked memory counter, reversible=yes
> * side-effect: KAPI_EFFECT_ALLOC_MEMORY, physical pages, May allocate and populate page table entries, condition=Pages not already present, reversible=yes
> * side-effect: KAPI_EFFECT_MODIFY_STATE | KAPI_EFFECT_ALLOC_MEMORY, page faults, Triggers page faults to bring pages into memory, condition=Pages not already resident
> * side-effect: KAPI_EFFECT_MODIFY_STATE, VMA splitting, May split existing VMAs at lock boundaries, condition=Lock range partially overlaps existing VMA
> * state-trans: memory pages, swappable, locked in RAM, Pages become non-swappable and pinned in physical memory
> * state-trans: VMA flags, unlocked, VM_LOCKED set, Virtual memory area marked as locked
> * capability: CAP_IPC_LOCK, KAPI_CAP_BYPASS_CHECK, CAP_IPC_LOCK capability
> * capability-allows: Lock unlimited amount of memory (no RLIMIT_MEMLOCK enforcement)
> * capability-without: Must respect RLIMIT_MEMLOCK resource limit
> * capability-condition: Checked when RLIMIT_MEMLOCK is 0 or locking would exceed limit
> * capability-priority: 0
> * constraint: RLIMIT_MEMLOCK Resource Limit, The RLIMIT_MEMLOCK soft resource limit specifies the maximum bytes of memory that may be locked into RAM. Unprivileged processes are restricted to this limit. CAP_IPC_LOCK capability allows bypassing this limit entirely. The limit is enforced per-process, not per-user.
> * constraint-expr: RLIMIT_MEMLOCK Resource Limit, locked_memory + request_size <= RLIMIT_MEMLOCK || CAP_IPC_LOCK
> * constraint: Memory Pressure and OOM, Locking large amounts of memory can cause system-wide memory pressure and potentially trigger the OOM killer. The kernel does not prevent locking memory that would destabilize the system.
> * constraint: Special Memory Areas, Some memory types cannot be locked or are silently skipped: VM_IO/VM_PFNMAP areas (device mappings) are skipped; Hugetlb pages are inherently pinned and skipped; DAX mappings are always present in memory and skipped; Secret memory (memfd_secret) mappings are skipped; VM_DROPPABLE memory cannot be locked and is skipped; Gate VMA (kernel entry point) is skipped; VM_LOCKED areas are already locked. These special areas are silently excluded without error.
> *
> * Context: Process context. May sleep. Takes mmap_lock for write.
> *
> * Return: 0 on success, negative error code on failure
Both of these, of course, are much less informative versions of the data
you have put up above; it would be nice to unify them somehow.
Thanks,
jon
^ permalink raw reply
* Re: [RFC v2 01/22] kernel/api: introduce kernel API specification framework
From: Sasha Levin @ 2025-07-01 20:50 UTC (permalink / raw)
To: Jonathan Corbet
Cc: Mauro Carvalho Chehab, linux-kernel, linux-doc, linux-api,
workflows, tools, Kate Stewart, Gabriele Paoloni, Chuck Wolber
In-Reply-To: <8734bfspko.fsf@trenco.lwn.net>
On Tue, Jul 01, 2025 at 01:01:27PM -0600, Jonathan Corbet wrote:
>[Adding some of the ELISA folks, who are working in a related area and
>might have thoughts on this. You can find the patch series under
>discussion at:
>
> https://lore.kernel.org/all/20250624180742.5795-1-sashal@kernel.org
Yup, we all met at OSS and reached the conclusion that we should lean
towards a machine readable spec, which we thought was closer to my
proposal than the kerneldoc work.
However, with your suggestion, I think it makes more sense to go back to
kerneldoc as that can be made machine readable.
>> In theory, all of that will let us have something like the following in
>> kerneldoc:
>>
>> - @api-type: syscall
>> - @api-version: 1
>> - @context-flags: KAPI_CTX_PROCESS | KAPI_CTX_SLEEPABLE
>> - @param-type: family, KAPI_TYPE_INT
>> - @param-flags: family, KAPI_PARAM_IN
>> - @param-range: family, 0, 45
>> - @param-mask: type, SOCK_TYPE_MASK | SOCK_CLOEXEC | SOCK_NONBLOCK
>> - @error-code: -EAFNOSUPPORT, "Address family not supported"
>> - @error-condition: -EAFNOSUPPORT, "family < 0 || family >= NPROTO"
>> - @capability: CAP_NET_RAW, KAPI_CAP_GRANT_PERMISSION
>> - @capability-allows: CAP_NET_RAW, "Create SOCK_RAW sockets"
>> - @since: 2.0
>> - @return-type: KAPI_TYPE_FD
>> - @return-check: KAPI_RETURN_ERROR_CHECK
>>
>> How does it sound? I'm pretty excited about the possiblity to align this
>> with kerneldoc. Please poke holes in the plan :)
>
>I think we could do it without all the @signs. We'd also want to see
>how well we could integrate that information with the minimal structure
>we already have: getting the return-value information into the Returns:
>section, for example, and tying the parameter constraints to the
>parameter descriptions we already have.
Right!
So I have a proof of concept which during the build process creates
.apispec.h which are generated from kerneldoc and contain macros
identical to the ones in my RFC.
Here's an example of sys_mlock() spec:
/**
* sys_mlock - Lock pages in memory
* @start: Starting address of memory range to lock
* @len: Length of memory range to lock in bytes
*
* Locks pages in the specified address range into RAM, preventing them from
* being paged to swap. Requires CAP_IPC_LOCK capability or RLIMIT_MEMLOCK
* resource limit.
*
* long-desc: Locks pages in the specified address range into RAM, preventing
* them from being paged to swap. Requires CAP_IPC_LOCK capability
* or RLIMIT_MEMLOCK resource limit.
* context-flags: KAPI_CTX_PROCESS | KAPI_CTX_SLEEPABLE
* param-type: start, KAPI_TYPE_UINT
* param-flags: start, KAPI_PARAM_IN
* param-constraint-type: start, KAPI_CONSTRAINT_NONE
* param-constraint: start, Rounded down to page boundary
* param-type: len, KAPI_TYPE_UINT
* param-flags: len, KAPI_PARAM_IN
* param-constraint-type: len, KAPI_CONSTRAINT_RANGE
* param-range: len, 0, LONG_MAX
* param-constraint: len, Rounded up to page boundary
* return-type: KAPI_TYPE_INT
* return-check-type: KAPI_RETURN_ERROR_CHECK
* return-success: 0
* error-code: -ENOMEM, ENOMEM, Address range issue,
* Some of the specified range is not mapped, has unmapped gaps,
* or the lock would cause the number of mapped regions to exceed the limit.
* error-code: -EPERM, EPERM, Insufficient privileges,
* The caller is not privileged (no CAP_IPC_LOCK) and RLIMIT_MEMLOCK is 0.
* error-code: -EINVAL, EINVAL, Address overflow,
* The result of the addition start+len was less than start (arithmetic overflow).
* error-code: -EAGAIN, EAGAIN, Some or all memory could not be locked,
* Some or all of the specified address range could not be locked.
* error-code: -EINTR, EINTR, Interrupted by signal,
* The operation was interrupted by a fatal signal before completion.
* error-code: -EFAULT, EFAULT, Bad address,
* The specified address range contains invalid addresses that cannot be accessed.
* since-version: 2.0
* lock: mmap_lock, KAPI_LOCK_RWLOCK
* lock-acquired: true
* lock-released: true
* lock-desc: Process memory map write lock
* signal: FATAL
* signal-direction: KAPI_SIGNAL_RECEIVE
* signal-action: KAPI_SIGNAL_ACTION_RETURN
* signal-condition: Fatal signal pending
* signal-desc: Fatal signals (SIGKILL) can interrupt the operation at two points:
* when acquiring mmap_write_lock_killable() and during page population
* in __mm_populate(). Returns -EINTR. Non-fatal signals do NOT interrupt
* mlock - the operation continues even if SIGINT/SIGTERM are received.
* signal-error: -EINTR
* signal-timing: KAPI_SIGNAL_TIME_DURING
* signal-priority: 0
* signal-interruptible: yes
* signal-state-req: KAPI_SIGNAL_STATE_RUNNING
* examples: mlock(addr, 4096); // Lock one page
* mlock(addr, len); // Lock range of pages
* notes: Memory locks do not stack - multiple calls on the same range can be
* undone by a single munlock. Locks are not inherited by child processes.
* Pages are locked on whole page boundaries. Commonly used by real-time
* applications to prevent page faults during time-critical operations.
* Also used for security to prevent sensitive data (e.g., cryptographic keys)
* from being written to swap. Note: locked pages may still be saved to
* swap during system suspend/hibernate.
*
* Tagged addresses are automatically handled via untagged_addr(). The operation
* occurs in two phases: first VMAs are marked with VM_LOCKED, then pages are
* populated into memory. When checking RLIMIT_MEMLOCK, the kernel optimizes
* by recounting locked memory to avoid double-counting overlapping regions.
* side-effect: KAPI_EFFECT_MODIFY_STATE | KAPI_EFFECT_ALLOC_MEMORY, process memory, Locks pages into physical memory, preventing swapping, reversible=yes
* side-effect: KAPI_EFFECT_MODIFY_STATE, mm->locked_vm, Increases process locked memory counter, reversible=yes
* side-effect: KAPI_EFFECT_ALLOC_MEMORY, physical pages, May allocate and populate page table entries, condition=Pages not already present, reversible=yes
* side-effect: KAPI_EFFECT_MODIFY_STATE | KAPI_EFFECT_ALLOC_MEMORY, page faults, Triggers page faults to bring pages into memory, condition=Pages not already resident
* side-effect: KAPI_EFFECT_MODIFY_STATE, VMA splitting, May split existing VMAs at lock boundaries, condition=Lock range partially overlaps existing VMA
* state-trans: memory pages, swappable, locked in RAM, Pages become non-swappable and pinned in physical memory
* state-trans: VMA flags, unlocked, VM_LOCKED set, Virtual memory area marked as locked
* capability: CAP_IPC_LOCK, KAPI_CAP_BYPASS_CHECK, CAP_IPC_LOCK capability
* capability-allows: Lock unlimited amount of memory (no RLIMIT_MEMLOCK enforcement)
* capability-without: Must respect RLIMIT_MEMLOCK resource limit
* capability-condition: Checked when RLIMIT_MEMLOCK is 0 or locking would exceed limit
* capability-priority: 0
* constraint: RLIMIT_MEMLOCK Resource Limit, The RLIMIT_MEMLOCK soft resource limit specifies the maximum bytes of memory that may be locked into RAM. Unprivileged processes are restricted to this limit. CAP_IPC_LOCK capability allows bypassing this limit entirely. The limit is enforced per-process, not per-user.
* constraint-expr: RLIMIT_MEMLOCK Resource Limit, locked_memory + request_size <= RLIMIT_MEMLOCK || CAP_IPC_LOCK
* constraint: Memory Pressure and OOM, Locking large amounts of memory can cause system-wide memory pressure and potentially trigger the OOM killer. The kernel does not prevent locking memory that would destabilize the system.
* constraint: Special Memory Areas, Some memory types cannot be locked or are silently skipped: VM_IO/VM_PFNMAP areas (device mappings) are skipped; Hugetlb pages are inherently pinned and skipped; DAX mappings are always present in memory and skipped; Secret memory (memfd_secret) mappings are skipped; VM_DROPPABLE memory cannot be locked and is skipped; Gate VMA (kernel entry point) is skipped; VM_LOCKED areas are already locked. These special areas are silently excluded without error.
*
* Context: Process context. May sleep. Takes mmap_lock for write.
*
* Return: 0 on success, negative error code on failure
*/
>The other thing I would really like to see, to the extent we can, is
>that a bunch of patches adding all this data to the source will actually
>be accepted by the relevant maintainers. It would be a shame to get all
>this infrastructure into place, then have things stall out due to
>maintainer pushback. Maybe you should start by annotating the
>scheduler-related system calls; if that works the rest should be a piece
>of cake :)
In the RFC I've sent out I've specced out API from different subsystems
to solicit some feedback on those, but so fair it's been quiet.
I'll resend a "lean" RFC v3 with just the base macro spec infra +
kerneldoc support + "tricker" sched API + "trickier" mm API.
I'm thinking that if it's still quiet in a month or two I'll propose a
talk at LPC around it, or maybe try and feedback/consensus during
maintainer's summit.
But yes, it doesn't make sense to take it in until we have an ack from a
few larger subsystems.
--
Thanks,
Sasha
^ permalink raw reply
* Re: [PATCH v6 5/6] fs: prepare for extending file_get/setattr()
From: Pali Rohár @ 2025-07-01 19:54 UTC (permalink / raw)
To: Darrick J. Wong
Cc: Amir Goldstein, Andrey Albershteyn, Arnd Bergmann,
Casey Schaufler, Christian Brauner, Jan Kara, Paul Moore,
linux-api, linux-fsdevel, linux-kernel, linux-xfs, selinux,
Andrey Albershteyn
In-Reply-To: <20250701194002.GS10009@frogsfrogsfrogs>
On Tuesday 01 July 2025 12:40:02 Darrick J. Wong wrote:
> On Tue, Jul 01, 2025 at 09:27:38PM +0200, Amir Goldstein wrote:
> > On Tue, Jul 1, 2025 at 8:31 PM Darrick J. Wong <djwong@kernel.org> wrote:
> > >
> > > On Mon, Jun 30, 2025 at 06:20:15PM +0200, Andrey Albershteyn wrote:
> > > > From: Amir Goldstein <amir73il@gmail.com>
> > > >
> > > > We intend to add support for more xflags to selective filesystems and
> > > > We cannot rely on copy_struct_from_user() to detect this extension.
> > > >
> > > > In preparation of extending the API, do not allow setting xflags unknown
> > > > by this kernel version.
> > > >
> > > > Also do not pass the read-only flags and read-only field fsx_nextents to
> > > > filesystem.
> > > >
> > > > These changes should not affect existing chattr programs that use the
> > > > ioctl to get fsxattr before setting the new values.
> > > >
> > > > Link: https://lore.kernel.org/linux-fsdevel/20250216164029.20673-4-pali@kernel.org/
> > > > Cc: Pali Rohár <pali@kernel.org>
> > > > Cc: Andrey Albershteyn <aalbersh@redhat.com>
> > > > Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> > > > Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
> > > > ---
> > > > fs/file_attr.c | 8 +++++++-
> > > > include/linux/fileattr.h | 20 ++++++++++++++++++++
> > > > 2 files changed, 27 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/fs/file_attr.c b/fs/file_attr.c
> > > > index 4e85fa00c092..62f08872d4ad 100644
> > > > --- a/fs/file_attr.c
> > > > +++ b/fs/file_attr.c
> > > > @@ -99,9 +99,10 @@ EXPORT_SYMBOL(vfs_fileattr_get);
> > > > int copy_fsxattr_to_user(const struct fileattr *fa, struct fsxattr __user *ufa)
> > > > {
> > > > struct fsxattr xfa;
> > > > + __u32 mask = FS_XFLAGS_MASK;
> > > >
> > > > memset(&xfa, 0, sizeof(xfa));
> > > > - xfa.fsx_xflags = fa->fsx_xflags;
> > > > + xfa.fsx_xflags = fa->fsx_xflags & mask;
> > >
> > > I wonder, should it be an error if a filesystem sets an fsx_xflags bit
> > > outside of FS_XFLAGS_MASK? I guess that's one way to prevent
> > > filesystems from overriding the VFS bits. ;)
> >
> > I think Pali has a plan on how to ensure that later
> > when the mask is provided via the API.
> >
> > >
> > > Though couldn't that be:
> > >
> > > xfa.fsx_xflags = fa->fsx_xflags & FS_XFLAGS_MASK;
> > >
> > > instead? And same below?
> > >
> >
> > Indeed. There is a reason for the var, because the next series
> > by Pali will use a user provided mask, which defaults to FS_XFLAGS_MASK,
> > so I left it this way.
> >
> > I don't see a problem with it keeping as is, but if it bothers you
> > I guess we can re-add the var later.
>
> Nah, it doesn't bother me that much.
>
> > > > xfa.fsx_extsize = fa->fsx_extsize;
> > > > xfa.fsx_nextents = fa->fsx_nextents;
> > > > xfa.fsx_projid = fa->fsx_projid;
> > > > @@ -118,11 +119,16 @@ static int copy_fsxattr_from_user(struct fileattr *fa,
> > > > struct fsxattr __user *ufa)
> > > > {
> > > > struct fsxattr xfa;
> > > > + __u32 mask = FS_XFLAGS_MASK;
> > > >
> > > > if (copy_from_user(&xfa, ufa, sizeof(xfa)))
> > > > return -EFAULT;
> > > >
> > > > + if (xfa.fsx_xflags & ~mask)
> > > > + return -EINVAL;
> > >
> > > I wonder if you want EOPNOTSUPP here? We don't know how to support
> > > unknown xflags. OTOH if you all have beaten this to death while I was
> > > out then don't start another round just for me. :P
> >
> > We have beaten this API almost to death for sure ;)
> > I don't remember if we discussed this specific aspect,
> > but I am personally in favor of
> > EOPNOTSUPP := the fs does not support the set/get operation
> > EINVAL := some flags provided as value is invalid
> >
> > For example, if the get API provides you with a mask of the
> > valid flags that you can set, if you try to set flags outside of
> > that mask you get EINVAL.
> >
> > That's my interpretation, but I agree that EOPNOTSUPP can also
> > make sense in this situation.
>
> <nod> I think I'd rather EOPNOTSUPP for "bits are set that the kernel
> doesn't recognize" and EINVAL (or maybe something else like
> EPROTONOSUPPORT) for "fs driver will not let you change this bit".
> At least for the syscall interface; we probably have to flatten that to
> EOPNOTSUPP for both legacy ioctls.
... and this starting to be complicated if the "fs driver" is network
based (as fs driver can support, but remote server not). See also:
https://lore.kernel.org/linux-fsdevel/20241224160535.pi6nazpugqkhvfns@pali/t/#u
For backup/restore application it would be very useful to distinguish between:
- "kernel does not support flag X"
- "target filesystem does not support flag X"
- "wrong structure was passed / syscall incorrectly called"
third option is bug in application - fatal error. second option is just
a warning for user (sorry, we cannot set NEW FEATURE on FAT32, but if
you would do restore to other fs, it is supported). and first option
happens when you run new application on older kernel version, it is an
recoverable error (or warning to user, but with more important level
then second option as switching to different FS would not help).
Could we return different errnos for these 3 situations?
> --D
>
> > Thanks,
> > Amir.
> >
^ permalink raw reply
page: next (older) | prev (newer) | latest
- recent:[subjects (threaded)|topics (new)|topics (active)]
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox