* Re: [PATCH V37 04/29] Enforce module signatures if the kernel is locked down
From: Jessica Yu @ 2019-08-08 10:01 UTC (permalink / raw)
To: Matthew Garrett
Cc: James Morris, LSM List, Linux Kernel Mailing List, Linux API,
David Howells, Kees Cook
In-Reply-To: <CACdnJusD_9W9tFqwKptDTA8fZU8HrSvsEQhKo0WS9QxLpgz5tA@mail.gmail.com>
+++ Matthew Garrett [01/08/19 13:42 -0700]:
>On Thu, Aug 1, 2019 at 7:22 AM Jessica Yu <jeyu@kernel.org> wrote:
>> Apologies if this was addressed in another patch in your series (I've
>> only skimmed the first few), but what should happen if the kernel is
>> locked down, but CONFIG_MODULE_SIG=n? Or shouldn't CONFIG_SECURITY_LOCKDOWN_LSM
>> depend on CONFIG_MODULE_SIG? Otherwise I think we'll end up calling
>> the empty !CONFIG_MODULE_SIG module_sig_check() stub even though
>> lockdown is enabled.
>
>Hm. Someone could certainly configure their kernel in that way. I'm
>not sure that tying CONFIG_SECURITY_LOCKDOWN_LSM to CONFIG_MODULE_SIG
>is the right solution, since the new LSM approach means that any other
>LSM could also impose the same policy. Perhaps we should just document
>this?
Hi Matthew,
If you're confident that a hard dependency is not the right approach,
then perhaps we could add a comment in the Kconfig (You could take a
look at the comment under MODULE_SIG_ALL in init/Kconfig for an
example)? If someone is configuring the kernel on their own then it'd
be nice to let them know, otherwise having a lockdown kernel without
module signatures would defeat the purpose of lockdown no? :-)
Thank you,
Jessica
^ permalink raw reply
* Re: [PATCH v5 1/6] mm/page_idle: Add per-pid idle page tracking using virtual index
From: Michal Hocko @ 2019-08-08 8:00 UTC (permalink / raw)
To: Joel Fernandes
Cc: Andrew Morton, linux-kernel, Alexey Dobriyan, Borislav Petkov,
Brendan Gregg, Catalin Marinas, Christian Hansen, dancol, fmayer,
H. Peter Anvin, Ingo Molnar, Jonathan Corbet, Kees Cook,
kernel-team, linux-api, linux-doc, linux-fsdevel, linux-mm,
Mike Rapoport, minchan, namhyung, paulmck, Robin Murphy,
Roman Gushchin, Stephen Rothwell
In-Reply-To: <20190807213105.GA14622@google.com>
On Wed 07-08-19 17:31:05, Joel Fernandes wrote:
> On Wed, Aug 07, 2019 at 01:58:40PM -0700, Andrew Morton wrote:
> > On Wed, 7 Aug 2019 16:45:30 -0400 Joel Fernandes <joel@joelfernandes.org> wrote:
> >
> > > On Wed, Aug 07, 2019 at 01:04:02PM -0700, Andrew Morton wrote:
> > > > On Wed, 7 Aug 2019 13:15:54 -0400 "Joel Fernandes (Google)" <joel@joelfernandes.org> wrote:
> > > >
> > > > > In Android, we are using this for the heap profiler (heapprofd) which
> > > > > profiles and pin points code paths which allocates and leaves memory
> > > > > idle for long periods of time. This method solves the security issue
> > > > > with userspace learning the PFN, and while at it is also shown to yield
> > > > > better results than the pagemap lookup, the theory being that the window
> > > > > where the address space can change is reduced by eliminating the
> > > > > intermediate pagemap look up stage. In virtual address indexing, the
> > > > > process's mmap_sem is held for the duration of the access.
> > > >
> > > > So is heapprofd a developer-only thing? Is heapprofd included in
> > > > end-user android loads? If not then, again, wouldn't it be better to
> > > > make the feature Kconfigurable so that Android developers can enable it
> > > > during development then disable it for production kernels?
> > >
> > > Almost all of this code is already configurable with
> > > CONFIG_IDLE_PAGE_TRACKING. If you disable it, then all of this code gets
> > > disabled.
> > >
> > > Or are you referring to something else that needs to be made configurable?
> >
> > Yes - the 300+ lines of code which this patchset adds!
> >
> > The impacted people will be those who use the existing
> > idle-page-tracking feature but who will not use the new feature. I
> > guess we can assume this set is small...
>
> Yes, I think this set should be small. The code size increase of page_idle.o
> is from ~1KB to ~2KB. Most of the extra space is consumed by
> page_idle_proc_generic() function which this patch adds. I don't think adding
> another CONFIG option to disable this while keeping existing
> CONFIG_IDLE_PAGE_TRACKING enabled, is worthwhile but I am open to the
> addition of such an option if anyone feels strongly about it. I believe that
> once this patch is merged, most like this new interface being added is what
> will be used more than the old interface (for some of the usecases) so it
> makes sense to keep it alive with CONFIG_IDLE_PAGE_TRACKING.
I would tend to agree with Joel here. The functionality falls into an
existing IDLE_PAGE_TRACKING config option quite nicely. If there really
are users who want to save some space and this is standing in the way
then they can easily add a new config option with some justification so
the savings are clear. Without that an additional config simply adds to
the already existing configurability complexity and balkanization.
--
Michal Hocko
SUSE Labs
^ permalink raw reply
* Re: [PATCHv5 06/37] alarmtimer: Provide get_timespec() callback
From: Andrei Vagin @ 2019-08-08 6:18 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Dmitry Safonov, linux-kernel, Dmitry Safonov, Adrian Reber,
Andrei Vagin, Andy Lutomirski, Arnd Bergmann, Christian Brauner,
Cyrill Gorcunov, Eric W. Biederman, H. Peter Anvin, Ingo Molnar,
Jann Horn, Jeff Dike, Oleg Nesterov, Pavel Emelyanov, Shuah Khan,
Vincenzo Frascino, containers, criu, linux-api, x86
In-Reply-To: <alpine.DEB.2.21.1908070803030.24014@nanos.tec.linutronix.de>
On Wed, Aug 07, 2019 at 08:04:10AM +0200, Thomas Gleixner wrote:
> On Mon, 29 Jul 2019, Dmitry Safonov wrote:
> > /**
> > @@ -869,8 +871,10 @@ static int __init alarmtimer_init(void)
> > /* Initialize alarm bases */
> > alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
> > alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
> > + alarm_bases[ALARM_REALTIME].get_timespec = posix_get_timespec,
>
> That's just wrong:
>
> > /*
> > * Get monotonic time for posix timers
> > */
> > -static int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
> > +int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
> > {
> > ktime_get_ts64(tp);
> > return 0;
>
> Using a proper function name would have avoided this.
You are right. Will fix. Thanks!
>
^ permalink raw reply
* [PATCH V38 29/29] lockdown: Print current->comm in restriction messages
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Matthew Garrett,
David Howells, Matthew Garrett, Kees Cook
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
Print the content of current->comm in messages generated by lockdown to
indicate a restriction that was hit. This makes it a bit easier to find
out what caused the message.
The message now patterned something like:
Lockdown: <comm>: <what> is restricted; see man kernel_lockdown.7
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
fs/proc/kcore.c | 5 +++--
security/lockdown/lockdown.c | 8 ++++++--
2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index ee2c576cc94e..e2ed8e08cc7a 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -548,11 +548,12 @@ static int open_kcore(struct inode *inode, struct file *filp)
{
int ret = security_locked_down(LOCKDOWN_KCORE);
- if (ret)
- return ret;
if (!capable(CAP_SYS_RAWIO))
return -EPERM;
+ if (ret)
+ return ret;
+
filp->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!filp->private_data)
return -ENOMEM;
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 173191562047..f6c74cf6a798 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -81,10 +81,14 @@ early_param("lockdown", lockdown_param);
*/
static int lockdown_is_locked_down(enum lockdown_reason what)
{
+ if (WARN(what >= LOCKDOWN_CONFIDENTIALITY_MAX,
+ "Invalid lockdown reason"))
+ return -EPERM;
+
if (kernel_locked_down >= what) {
if (lockdown_reasons[what])
- pr_notice("Lockdown: %s is restricted; see man kernel_lockdown.7\n",
- lockdown_reasons[what]);
+ pr_notice("Lockdown: %s: %s is restricted; see man kernel_lockdown.7\n",
+ current->comm, lockdown_reasons[what]);
return -EPERM;
}
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Matthew Garrett,
Matthew Garrett, Ard Biesheuvel, Kees Cook, linux-efi
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
efivar_ssdt_load allows the kernel to import arbitrary ACPI code from an
EFI variable, which gives arbitrary code execution in ring 0. Prevent
that when the kernel is locked down.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-efi@vger.kernel.org
---
drivers/firmware/efi/efi.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index ad3b1f4866b3..776f479e5499 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -30,6 +30,7 @@
#include <linux/acpi.h>
#include <linux/ucs2_string.h>
#include <linux/memblock.h>
+#include <linux/security.h>
#include <asm/early_ioremap.h>
@@ -242,6 +243,11 @@ static void generic_ops_unregister(void)
static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX] __initdata;
static int __init efivar_ssdt_setup(char *str)
{
+ int ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
+
+ if (ret)
+ return ret;
+
if (strlen(str) < sizeof(efivar_ssdt))
memcpy(efivar_ssdt, str, strlen(str));
else
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 27/29] tracefs: Restrict tracefs when the kernel is locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Matthew Garrett,
Matthew Garrett, Steven Rostedt
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
Tracefs may release more information about the kernel than desirable, so
restrict it when the kernel is locked down in confidentiality mode by
preventing open().
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
fs/tracefs/inode.c | 40 +++++++++++++++++++++++++++++++++++-
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
3 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index 1387bcd96a79..12a325fb4cbd 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -21,6 +21,7 @@
#include <linux/seq_file.h>
#include <linux/magic.h>
#include <linux/slab.h>
+#include <linux/security.h>
#define TRACEFS_DEFAULT_MODE 0700
@@ -28,6 +29,23 @@ static struct vfsmount *tracefs_mount;
static int tracefs_mount_count;
static bool tracefs_registered;
+static int default_open_file(struct inode *inode, struct file *filp)
+{
+ struct dentry *dentry = filp->f_path.dentry;
+ struct file_operations *real_fops;
+ int ret;
+
+ if (!dentry)
+ return -EINVAL;
+
+ ret = security_locked_down(LOCKDOWN_TRACEFS);
+ if (ret)
+ return ret;
+
+ real_fops = dentry->d_fsdata;
+ return real_fops->open(inode, filp);
+}
+
static ssize_t default_read_file(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
@@ -210,6 +228,12 @@ static int tracefs_apply_options(struct super_block *sb)
return 0;
}
+static void tracefs_destroy_inode(struct inode *inode)
+{
+ if (S_ISREG(inode->i_mode))
+ kfree(inode->i_fop);
+}
+
static int tracefs_reconfigure(struct fs_context *fc)
{
struct super_block *sb = fc->root->d_sb;
@@ -236,6 +260,7 @@ static int tracefs_show_options(struct seq_file *m, struct dentry *root)
static const struct super_operations tracefs_super_operations = {
.statfs = simple_statfs,
+ .destroy_inode = tracefs_destroy_inode,
.show_options = tracefs_show_options,
};
@@ -372,6 +397,7 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops)
{
+ struct file_operations *proxy_fops;
struct dentry *dentry;
struct inode *inode;
@@ -387,8 +413,20 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
if (unlikely(!inode))
return failed_creating(dentry);
+ proxy_fops = kzalloc(sizeof(struct file_operations), GFP_KERNEL);
+ if (unlikely(!proxy_fops)) {
+ iput(inode);
+ return failed_creating(dentry);
+ }
+
+ if (!fops)
+ fops = &tracefs_file_operations;
+
+ dentry->d_fsdata = (void *)fops;
+ memcpy(proxy_fops, fops, sizeof(*proxy_fops));
+ proxy_fops->open = default_open_file;
inode->i_mode = mode;
- inode->i_fop = fops ? fops : &tracefs_file_operations;
+ inode->i_fop = proxy_fops;
inode->i_private = data;
d_instantiate(dentry, inode);
fsnotify_create(dentry->d_parent->d_inode, dentry);
diff --git a/include/linux/security.h b/include/linux/security.h
index d92323b44a3f..807dc0d24982 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -121,6 +121,7 @@ enum lockdown_reason {
LOCKDOWN_KPROBES,
LOCKDOWN_BPF_READ,
LOCKDOWN_PERF,
+ LOCKDOWN_TRACEFS,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 88064ce1c844..173191562047 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -36,6 +36,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_KPROBES] = "use of kprobes",
[LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM",
[LOCKDOWN_PERF] = "unsafe use of perf",
+ [LOCKDOWN_TRACEFS] = "use of tracefs",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 26/29] debugfs: Restrict debugfs when the kernel is locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, David Howells,
Andy Shevchenko, acpi4asus-user, platform-driver-x86,
Matthew Garrett, Thomas Gleixner, Greg KH, Rafael J . Wysocki,
Matthew Garrett
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: David Howells <dhowells@redhat.com>
Disallow opening of debugfs files that might be used to muck around when
the kernel is locked down as various drivers give raw access to hardware
through debugfs. Given the effort of auditing all 2000 or so files and
manually fixing each one as necessary, I've chosen to apply a heuristic
instead. The following changes are made:
(1) chmod and chown are disallowed on debugfs objects (though the root dir
can be modified by mount and remount, but I'm not worried about that).
(2) When the kernel is locked down, only files with the following criteria
are permitted to be opened:
- The file must have mode 00444
- The file must not have ioctl methods
- The file must not have mmap
(3) When the kernel is locked down, files may only be opened for reading.
Normal device interaction should be done through configfs, sysfs or a
miscdev, not debugfs.
Note that this makes it unnecessary to specifically lock down show_dsts(),
show_devs() and show_call() in the asus-wmi driver.
I would actually prefer to lock down all files by default and have the
the files unlocked by the creator. This is tricky to manage correctly,
though, as there are 19 creation functions and ~1600 call sites (some of
them in loops scanning tables).
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Andy Shevchenko <andy.shevchenko@gmail.com>
cc: acpi4asus-user@lists.sourceforge.net
cc: platform-driver-x86@vger.kernel.org
cc: Matthew Garrett <mjg59@srcf.ucam.org>
cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Matthew Garrett <matthewgarrett@google.com>
---
fs/debugfs/file.c | 30 ++++++++++++++++++++++++++++++
fs/debugfs/inode.c | 32 ++++++++++++++++++++++++++++++--
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
4 files changed, 62 insertions(+), 2 deletions(-)
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 93e4ca6b2ad7..87846aad594b 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -19,6 +19,7 @@
#include <linux/atomic.h>
#include <linux/device.h>
#include <linux/poll.h>
+#include <linux/security.h>
#include "internal.h"
@@ -136,6 +137,25 @@ void debugfs_file_put(struct dentry *dentry)
}
EXPORT_SYMBOL_GPL(debugfs_file_put);
+/*
+ * Only permit access to world-readable files when the kernel is locked down.
+ * We also need to exclude any file that has ways to write or alter it as root
+ * can bypass the permissions check.
+ */
+static bool debugfs_is_locked_down(struct inode *inode,
+ struct file *filp,
+ const struct file_operations *real_fops)
+{
+ if ((inode->i_mode & 07777) == 0444 &&
+ !(filp->f_mode & FMODE_WRITE) &&
+ !real_fops->unlocked_ioctl &&
+ !real_fops->compat_ioctl &&
+ !real_fops->mmap)
+ return false;
+
+ return security_locked_down(LOCKDOWN_DEBUGFS);
+}
+
static int open_proxy_open(struct inode *inode, struct file *filp)
{
struct dentry *dentry = F_DENTRY(filp);
@@ -147,6 +167,11 @@ static int open_proxy_open(struct inode *inode, struct file *filp)
return r == -EIO ? -ENOENT : r;
real_fops = debugfs_real_fops(filp);
+
+ r = debugfs_is_locked_down(inode, filp, real_fops);
+ if (r)
+ goto out;
+
real_fops = fops_get(real_fops);
if (!real_fops) {
/* Huh? Module did not clean up after itself at exit? */
@@ -272,6 +297,11 @@ static int full_proxy_open(struct inode *inode, struct file *filp)
return r == -EIO ? -ENOENT : r;
real_fops = debugfs_real_fops(filp);
+
+ r = debugfs_is_locked_down(inode, filp, real_fops);
+ if (r)
+ goto out;
+
real_fops = fops_get(real_fops);
if (!real_fops) {
/* Huh? Module did not cleanup after itself at exit? */
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index ec5c197985ec..51ced4ae9280 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -27,6 +27,7 @@
#include <linux/seq_file.h>
#include <linux/magic.h>
#include <linux/slab.h>
+#include <linux/security.h>
#include "internal.h"
@@ -36,6 +37,32 @@ static struct vfsmount *debugfs_mount;
static int debugfs_mount_count;
static bool debugfs_registered;
+/*
+ * Don't allow access attributes to be changed whilst the kernel is locked down
+ * so that we can use the file mode as part of a heuristic to determine whether
+ * to lock down individual files.
+ */
+static int debugfs_setattr(struct dentry *dentry, struct iattr *ia)
+{
+ int ret = security_locked_down(LOCKDOWN_DEBUGFS);
+
+ if (ret && (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
+ return ret;
+ return simple_setattr(dentry, ia);
+}
+
+static const struct inode_operations debugfs_file_inode_operations = {
+ .setattr = debugfs_setattr,
+};
+static const struct inode_operations debugfs_dir_inode_operations = {
+ .lookup = simple_lookup,
+ .setattr = debugfs_setattr,
+};
+static const struct inode_operations debugfs_symlink_inode_operations = {
+ .get_link = simple_get_link,
+ .setattr = debugfs_setattr,
+};
+
static struct inode *debugfs_get_inode(struct super_block *sb)
{
struct inode *inode = new_inode(sb);
@@ -353,6 +380,7 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
inode->i_mode = mode;
inode->i_private = data;
+ inode->i_op = &debugfs_file_inode_operations;
inode->i_fop = proxy_fops;
dentry->d_fsdata = (void *)((unsigned long)real_fops |
DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
@@ -516,7 +544,7 @@ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
}
inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
- inode->i_op = &simple_dir_inode_operations;
+ inode->i_op = &debugfs_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
@@ -616,7 +644,7 @@ struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
return failed_creating(dentry);
}
inode->i_mode = S_IFLNK | S_IRWXUGO;
- inode->i_op = &simple_symlink_inode_operations;
+ inode->i_op = &debugfs_symlink_inode_operations;
inode->i_link = link;
d_instantiate(dentry, inode);
return end_creating(dentry);
diff --git a/include/linux/security.h b/include/linux/security.h
index 8ef366de70b0..d92323b44a3f 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -115,6 +115,7 @@ enum lockdown_reason {
LOCKDOWN_TIOCSSERIAL,
LOCKDOWN_MODULE_PARAMETERS,
LOCKDOWN_MMIOTRACE,
+ LOCKDOWN_DEBUGFS,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_KCORE,
LOCKDOWN_KPROBES,
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index fb437a7ef5f2..88064ce1c844 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -30,6 +30,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
[LOCKDOWN_MMIOTRACE] = "unsafe mmio",
+ [LOCKDOWN_DEBUGFS] = "debugfs access",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_KCORE] = "/proc/kcore access",
[LOCKDOWN_KPROBES] = "use of kprobes",
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 25/29] kexec: Allow kexec_file() with appropriate IMA policy when locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Matthew Garrett,
Matthew Garrett, Mimi Zohar, Dmitry Kasatkin, linux-integrity
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
Systems in lockdown mode should block the kexec of untrusted kernels.
For x86 and ARM we can ensure that a kernel is trustworthy by validating
a PE signature, but this isn't possible on other architectures. On those
platforms we can use IMA digital signatures instead. Add a function to
determine whether IMA has or will verify signatures for a given event type,
and if so permit kexec_file() even if the kernel is otherwise locked down.
This is restricted to cases where CONFIG_INTEGRITY_TRUSTED_KEYRING is set
in order to prevent an attacker from loading additional keys at runtime.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: linux-integrity@vger.kernel.org
---
include/linux/ima.h | 9 ++++++
kernel/kexec_file.c | 12 +++++--
security/integrity/ima/ima.h | 2 ++
security/integrity/ima/ima_main.c | 2 +-
security/integrity/ima/ima_policy.c | 50 +++++++++++++++++++++++++++++
5 files changed, 72 insertions(+), 3 deletions(-)
diff --git a/include/linux/ima.h b/include/linux/ima.h
index a20ad398d260..1c37f17f7203 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -131,4 +131,13 @@ static inline int ima_inode_removexattr(struct dentry *dentry,
return 0;
}
#endif /* CONFIG_IMA_APPRAISE */
+
+#if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
+extern bool ima_appraise_signature(enum kernel_read_file_id func);
+#else
+static inline bool ima_appraise_signature(enum kernel_read_file_id func)
+{
+ return false;
+}
+#endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */
#endif /* _LINUX_IMA_H */
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index dd06f1070d66..13c9960a5860 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -228,9 +228,17 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
goto out;
}
- ret = security_locked_down(LOCKDOWN_KEXEC);
- if (ret)
+ ret = 0;
+
+ /* If IMA is guaranteed to appraise a signature on the kexec
+ * image, permit it even if the kernel is otherwise locked
+ * down.
+ */
+ if (!ima_appraise_signature(READING_KEXEC_IMAGE) &&
+ security_locked_down(LOCKDOWN_KEXEC)) {
+ ret = -EPERM;
goto out;
+ }
break;
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 011b91c79351..64dcb11cf444 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -113,6 +113,8 @@ struct ima_kexec_hdr {
u64 count;
};
+extern const int read_idmap[];
+
#ifdef CONFIG_HAVE_IMA_KEXEC
void ima_load_kexec_buffer(void);
#else
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 584019728660..b9f57503af2c 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -502,7 +502,7 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
return 0;
}
-static const int read_idmap[READING_MAX_ID] = {
+const int read_idmap[READING_MAX_ID] = {
[READING_FIRMWARE] = FIRMWARE_CHECK,
[READING_FIRMWARE_PREALLOC_BUFFER] = FIRMWARE_CHECK,
[READING_MODULE] = MODULE_CHECK,
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 6df7f641ff66..827f1e33fe86 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -1456,3 +1456,53 @@ int ima_policy_show(struct seq_file *m, void *v)
return 0;
}
#endif /* CONFIG_IMA_READ_POLICY */
+
+#if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
+/*
+ * ima_appraise_signature: whether IMA will appraise a given function using
+ * an IMA digital signature. This is restricted to cases where the kernel
+ * has a set of built-in trusted keys in order to avoid an attacker simply
+ * loading additional keys.
+ */
+bool ima_appraise_signature(enum kernel_read_file_id id)
+{
+ struct ima_rule_entry *entry;
+ bool found = false;
+ enum ima_hooks func;
+
+ if (id >= READING_MAX_ID)
+ return false;
+
+ func = read_idmap[id] ?: FILE_CHECK;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(entry, ima_rules, list) {
+ if (entry->action != APPRAISE)
+ continue;
+
+ /*
+ * A generic entry will match, but otherwise require that it
+ * match the func we're looking for
+ */
+ if (entry->func && entry->func != func)
+ continue;
+
+ /*
+ * We require this to be a digital signature, not a raw IMA
+ * hash.
+ */
+ if (entry->flags & IMA_DIGSIG_REQUIRED)
+ found = true;
+
+ /*
+ * We've found a rule that matches, so break now even if it
+ * didn't require a digital signature - a later rule that does
+ * won't override it, so would be a false positive.
+ */
+ break;
+ }
+
+ rcu_read_unlock();
+ return found;
+}
+#endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 24/29] Lock down perf when in confidentiality mode
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, David Howells,
Matthew Garrett, Kees Cook, Peter Zijlstra, Ingo Molnar,
Arnaldo Carvalho de Melo
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: David Howells <dhowells@redhat.com>
Disallow the use of certain perf facilities that might allow userspace to
access kernel data.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
---
include/linux/security.h | 1 +
kernel/events/core.c | 7 +++++++
security/lockdown/lockdown.c | 1 +
3 files changed, 9 insertions(+)
diff --git a/include/linux/security.h b/include/linux/security.h
index 8dd1741a52cd..8ef366de70b0 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -119,6 +119,7 @@ enum lockdown_reason {
LOCKDOWN_KCORE,
LOCKDOWN_KPROBES,
LOCKDOWN_BPF_READ,
+ LOCKDOWN_PERF,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/kernel/events/core.c b/kernel/events/core.c
index c1f52a749db2..5c520b60163a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10826,6 +10826,13 @@ SYSCALL_DEFINE5(perf_event_open,
perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
return -EACCES;
+ err = security_locked_down(LOCKDOWN_PERF);
+ if (err && (attr.sample_type & PERF_SAMPLE_REGS_INTR))
+ /* REGS_INTR can leak data, lockdown must prevent this */
+ return err;
+
+ err = 0;
+
/*
* In cgroup mode, the pid argument is used to pass the fd
* opened to the cgroup directory in cgroupfs. The cpu argument
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 1b89d3e8e54d..fb437a7ef5f2 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -34,6 +34,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_KCORE] = "/proc/kcore access",
[LOCKDOWN_KPROBES] = "use of kprobes",
[LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM",
+ [LOCKDOWN_PERF] = "unsafe use of perf",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 23/29] bpf: Restrict bpf when kernel lockdown is in confidentiality mode
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, David Howells,
Alexei Starovoitov, Matthew Garrett, Kees Cook, netdev,
Chun-Yi Lee, Daniel Borkmann
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: David Howells <dhowells@redhat.com>
bpf_read() and bpf_read_str() could potentially be abused to (eg) allow
private keys in kernel memory to be leaked. Disable them if the kernel
has been locked down in confidentiality mode.
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: netdev@vger.kernel.org
cc: Chun-Yi Lee <jlee@suse.com>
cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
---
include/linux/security.h | 1 +
kernel/trace/bpf_trace.c | 10 ++++++++++
security/lockdown/lockdown.c | 1 +
3 files changed, 12 insertions(+)
diff --git a/include/linux/security.h b/include/linux/security.h
index 987d8427f091..8dd1741a52cd 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -118,6 +118,7 @@ enum lockdown_reason {
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_KCORE,
LOCKDOWN_KPROBES,
+ LOCKDOWN_BPF_READ,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index ca1255d14576..492a8bfaae98 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -142,8 +142,13 @@ BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr)
{
int ret;
+ ret = security_locked_down(LOCKDOWN_BPF_READ);
+ if (ret < 0)
+ goto out;
+
ret = probe_kernel_read(dst, unsafe_ptr, size);
if (unlikely(ret < 0))
+out:
memset(dst, 0, size);
return ret;
@@ -569,6 +574,10 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
{
int ret;
+ ret = security_locked_down(LOCKDOWN_BPF_READ);
+ if (ret < 0)
+ goto out;
+
/*
* The strncpy_from_unsafe() call will likely not fill the entire
* buffer, but that's okay in this circumstance as we're probing
@@ -580,6 +589,7 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
*/
ret = strncpy_from_unsafe(dst, unsafe_ptr, size);
if (unlikely(ret < 0))
+out:
memset(dst, 0, size);
return ret;
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 6b123cbf3748..1b89d3e8e54d 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -33,6 +33,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_KCORE] = "/proc/kcore access",
[LOCKDOWN_KPROBES] = "use of kprobes",
+ [LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 22/29] Lock down tracing and perf kprobes when in confidentiality mode
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, David Howells,
Alexei Starovoitov, Matthew Garrett, Masami Hiramatsu, Kees Cook,
Naveen N . Rao, Anil S Keshavamurthy, davem
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: David Howells <dhowells@redhat.com>
Disallow the creation of perf and ftrace kprobes when the kernel is
locked down in confidentiality mode by preventing their registration.
This prevents kprobes from being used to access kernel memory to steal
crypto data, but continues to allow the use of kprobes from signed
modules.
Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: davem@davemloft.net
Cc: Masami Hiramatsu <mhiramat@kernel.org>
---
include/linux/security.h | 1 +
kernel/trace/trace_kprobe.c | 5 +++++
security/lockdown/lockdown.c | 1 +
3 files changed, 7 insertions(+)
diff --git a/include/linux/security.h b/include/linux/security.h
index f0cffd0977d3..987d8427f091 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -117,6 +117,7 @@ enum lockdown_reason {
LOCKDOWN_MMIOTRACE,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_KCORE,
+ LOCKDOWN_KPROBES,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 9d483ad9bb6c..d5fbade68b33 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -11,6 +11,7 @@
#include <linux/uaccess.h>
#include <linux/rculist.h>
#include <linux/error-injection.h>
+#include <linux/security.h>
#include <asm/setup.h> /* for COMMAND_LINE_SIZE */
@@ -389,6 +390,10 @@ static int __register_trace_kprobe(struct trace_kprobe *tk)
{
int i, ret;
+ ret = security_locked_down(LOCKDOWN_KPROBES);
+ if (ret)
+ return ret;
+
if (trace_kprobe_is_registered(tk))
return -EINVAL;
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index c050b82c7f9f..6b123cbf3748 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -32,6 +32,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_MMIOTRACE] = "unsafe mmio",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_KCORE] = "/proc/kcore access",
+ [LOCKDOWN_KPROBES] = "use of kprobes",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 21/29] Lock down /proc/kcore
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, David Howells,
Matthew Garrett, Kees Cook
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: David Howells <dhowells@redhat.com>
Disallow access to /proc/kcore when the kernel is locked down to prevent
access to cryptographic data. This is limited to lockdown
confidentiality mode and is still permitted in integrity mode.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
fs/proc/kcore.c | 5 +++++
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
3 files changed, 7 insertions(+)
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index f5834488b67d..ee2c576cc94e 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -31,6 +31,7 @@
#include <linux/ioport.h>
#include <linux/memory.h>
#include <linux/sched/task.h>
+#include <linux/security.h>
#include <asm/sections.h>
#include "internal.h"
@@ -545,6 +546,10 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
static int open_kcore(struct inode *inode, struct file *filp)
{
+ int ret = security_locked_down(LOCKDOWN_KCORE);
+
+ if (ret)
+ return ret;
if (!capable(CAP_SYS_RAWIO))
return -EPERM;
diff --git a/include/linux/security.h b/include/linux/security.h
index 3f7b6a4cd65a..f0cffd0977d3 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -116,6 +116,7 @@ enum lockdown_reason {
LOCKDOWN_MODULE_PARAMETERS,
LOCKDOWN_MMIOTRACE,
LOCKDOWN_INTEGRITY_MAX,
+ LOCKDOWN_KCORE,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 37b7d7e50474..c050b82c7f9f 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -31,6 +31,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
[LOCKDOWN_MMIOTRACE] = "unsafe mmio",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
+ [LOCKDOWN_KCORE] = "/proc/kcore access",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 20/29] x86/mmiotrace: Lock down the testmmiotrace module
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, David Howells,
Thomas Gleixner, Matthew Garrett, Steven Rostedt, Kees Cook,
Ingo Molnar, H. Peter Anvin, x86
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: David Howells <dhowells@redhat.com>
The testmmiotrace module shouldn't be permitted when the kernel is locked
down as it can be used to arbitrarily read and write MMIO space. This is
a runtime check rather than buildtime in order to allow configurations
where the same kernel may be run in both locked down or permissive modes
depending on local policy.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Howells <dhowells@redhat.com
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: Thomas Gleixner <tglx@linutronix.de>
cc: Steven Rostedt <rostedt@goodmis.org>
cc: Ingo Molnar <mingo@kernel.org>
cc: "H. Peter Anvin" <hpa@zytor.com>
cc: x86@kernel.org
---
arch/x86/mm/testmmiotrace.c | 5 +++++
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
3 files changed, 7 insertions(+)
diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c
index 0881e1ff1e58..a8bd952e136d 100644
--- a/arch/x86/mm/testmmiotrace.c
+++ b/arch/x86/mm/testmmiotrace.c
@@ -8,6 +8,7 @@
#include <linux/module.h>
#include <linux/io.h>
#include <linux/mmiotrace.h>
+#include <linux/security.h>
static unsigned long mmio_address;
module_param_hw(mmio_address, ulong, iomem, 0);
@@ -115,6 +116,10 @@ static void do_test_bulk_ioremapping(void)
static int __init init(void)
{
unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
+ int ret = security_locked_down(LOCKDOWN_MMIOTRACE);
+
+ if (ret)
+ return ret;
if (mmio_address == 0) {
pr_err("you have to use the module argument mmio_address.\n");
diff --git a/include/linux/security.h b/include/linux/security.h
index 43fa3486522b..3f7b6a4cd65a 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -114,6 +114,7 @@ enum lockdown_reason {
LOCKDOWN_PCMCIA_CIS,
LOCKDOWN_TIOCSSERIAL,
LOCKDOWN_MODULE_PARAMETERS,
+ LOCKDOWN_MMIOTRACE,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 5177938cfa0d..37b7d7e50474 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -29,6 +29,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
+ [LOCKDOWN_MMIOTRACE] = "unsafe mmio",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 19/29] Lock down module params that specify hardware parameters (eg. ioport)
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, David Howells,
Alan Cox, Matthew Garrett, Kees Cook, Jessica Yu
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: David Howells <dhowells@redhat.com>
Provided an annotation for module parameters that specify hardware
parameters (such as io ports, iomem addresses, irqs, dma channels, fixed
dma buffers and other types).
Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Jessica Yu <jeyu@kernel.org>
---
include/linux/security.h | 1 +
kernel/params.c | 27 ++++++++++++++++++++++-----
security/lockdown/lockdown.c | 1 +
3 files changed, 24 insertions(+), 5 deletions(-)
diff --git a/include/linux/security.h b/include/linux/security.h
index 8f7048395114..43fa3486522b 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -113,6 +113,7 @@ enum lockdown_reason {
LOCKDOWN_ACPI_TABLES,
LOCKDOWN_PCMCIA_CIS,
LOCKDOWN_TIOCSSERIAL,
+ LOCKDOWN_MODULE_PARAMETERS,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/kernel/params.c b/kernel/params.c
index cf448785d058..35f138fce762 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -12,6 +12,7 @@
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/ctype.h>
+#include <linux/security.h>
#ifdef CONFIG_SYSFS
/* Protects all built-in parameters, modules use their own param_lock */
@@ -96,13 +97,19 @@ bool parameq(const char *a, const char *b)
return parameqn(a, b, strlen(a)+1);
}
-static void param_check_unsafe(const struct kernel_param *kp)
+static bool param_check_unsafe(const struct kernel_param *kp)
{
+ if (kp->flags & KERNEL_PARAM_FL_HWPARAM &&
+ security_locked_down(LOCKDOWN_MODULE_PARAMETERS))
+ return false;
+
if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
pr_notice("Setting dangerous option %s - tainting kernel\n",
kp->name);
add_taint(TAINT_USER, LOCKDEP_STILL_OK);
}
+
+ return true;
}
static int parse_one(char *param,
@@ -132,8 +139,10 @@ static int parse_one(char *param,
pr_debug("handling %s with %p\n", param,
params[i].ops->set);
kernel_param_lock(params[i].mod);
- param_check_unsafe(¶ms[i]);
- err = params[i].ops->set(val, ¶ms[i]);
+ if (param_check_unsafe(¶ms[i]))
+ err = params[i].ops->set(val, ¶ms[i]);
+ else
+ err = -EPERM;
kernel_param_unlock(params[i].mod);
return err;
}
@@ -541,6 +550,12 @@ static ssize_t param_attr_show(struct module_attribute *mattr,
return count;
}
+#ifdef CONFIG_MODULES
+#define mod_name(mod) ((mod)->name)
+#else
+#define mod_name(mod) "unknown"
+#endif
+
/* sysfs always hands a nul-terminated string in buf. We rely on that. */
static ssize_t param_attr_store(struct module_attribute *mattr,
struct module_kobject *mk,
@@ -553,8 +568,10 @@ static ssize_t param_attr_store(struct module_attribute *mattr,
return -EPERM;
kernel_param_lock(mk->mod);
- param_check_unsafe(attribute->param);
- err = attribute->param->ops->set(buf, attribute->param);
+ if (param_check_unsafe(attribute->param))
+ err = attribute->param->ops->set(buf, attribute->param);
+ else
+ err = -EPERM;
kernel_param_unlock(mk->mod);
if (!err)
return len;
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 00a3a6438dd2..5177938cfa0d 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -28,6 +28,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables",
[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
+ [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 18/29] Lock down TIOCSSERIAL
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, David Howells,
Greg Kroah-Hartman, Matthew Garrett, Kees Cook, Jiri Slaby,
linux-serial
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: David Howells <dhowells@redhat.com>
Lock down TIOCSSERIAL as that can be used to change the ioport and irq
settings on a serial port. This only appears to be an issue for the serial
drivers that use the core serial code. All other drivers seem to either
ignore attempts to change port/irq or give an error.
Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
---
drivers/tty/serial/serial_core.c | 5 +++++
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
3 files changed, 7 insertions(+)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 4223cb496764..6e713be1d4e9 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -22,6 +22,7 @@
#include <linux/serial_core.h>
#include <linux/delay.h>
#include <linux/mutex.h>
+#include <linux/security.h>
#include <linux/irq.h>
#include <linux/uaccess.h>
@@ -862,6 +863,10 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
goto check_and_exit;
}
+ retval = security_locked_down(LOCKDOWN_TIOCSSERIAL);
+ if (retval && (change_irq || change_port))
+ goto exit;
+
/*
* Ask the low level driver to verify the settings.
*/
diff --git a/include/linux/security.h b/include/linux/security.h
index 3773ad09b831..8f7048395114 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -112,6 +112,7 @@ enum lockdown_reason {
LOCKDOWN_MSR,
LOCKDOWN_ACPI_TABLES,
LOCKDOWN_PCMCIA_CIS,
+ LOCKDOWN_TIOCSSERIAL,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 22482e1b9a77..00a3a6438dd2 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -27,6 +27,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_MSR] = "raw MSR access",
[LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables",
[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
+ [LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 17/29] Prohibit PCMCIA CIS storage when the kernel is locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, David Howells,
Dominik Brodowski, Matthew Garrett, Kees Cook
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: David Howells <dhowells@redhat.com>
Prohibit replacement of the PCMCIA Card Information Structure when the
kernel is locked down.
Suggested-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
drivers/pcmcia/cistpl.c | 5 +++++
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
3 files changed, 7 insertions(+)
diff --git a/drivers/pcmcia/cistpl.c b/drivers/pcmcia/cistpl.c
index abd029945cc8..629359fe3513 100644
--- a/drivers/pcmcia/cistpl.c
+++ b/drivers/pcmcia/cistpl.c
@@ -21,6 +21,7 @@
#include <linux/pci.h>
#include <linux/ioport.h>
#include <linux/io.h>
+#include <linux/security.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>
@@ -1575,6 +1576,10 @@ static ssize_t pccard_store_cis(struct file *filp, struct kobject *kobj,
struct pcmcia_socket *s;
int error;
+ error = security_locked_down(LOCKDOWN_PCMCIA_CIS);
+ if (error)
+ return error;
+
s = to_socket(container_of(kobj, struct device, kobj));
if (off)
diff --git a/include/linux/security.h b/include/linux/security.h
index 1c32522b3c5a..3773ad09b831 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -111,6 +111,7 @@ enum lockdown_reason {
LOCKDOWN_IOPORT,
LOCKDOWN_MSR,
LOCKDOWN_ACPI_TABLES,
+ LOCKDOWN_PCMCIA_CIS,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index ecb51b1a5c03..22482e1b9a77 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -26,6 +26,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_IOPORT] = "raw io port access",
[LOCKDOWN_MSR] = "raw MSR access",
[LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables",
+ [LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 16/29] acpi: Disable ACPI table override if the kernel is locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Linn Crosetto,
David Howells, Matthew Garrett, Kees Cook, linux-acpi
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: Linn Crosetto <lcrosetto@gmail.com>
>From the kernel documentation (initrd_table_override.txt):
If the ACPI_INITRD_TABLE_OVERRIDE compile option is true, it is possible
to override nearly any ACPI table provided by the BIOS with an
instrumented, modified one.
When lockdown is enabled, the kernel should disallow any unauthenticated
changes to kernel space. ACPI tables contain code invoked by the kernel,
so do not allow ACPI tables to be overridden if the kernel is locked down.
Signed-off-by: Linn Crosetto <lcrosetto@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: linux-acpi@vger.kernel.org
---
drivers/acpi/tables.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index b32327759380..180ac4329763 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -20,6 +20,7 @@
#include <linux/memblock.h>
#include <linux/earlycpio.h>
#include <linux/initrd.h>
+#include <linux/security.h>
#include "internal.h"
#ifdef CONFIG_ACPI_CUSTOM_DSDT
@@ -578,6 +579,11 @@ void __init acpi_table_upgrade(void)
if (table_nr == 0)
return;
+ if (security_locked_down(LOCKDOWN_ACPI_TABLES)) {
+ pr_notice("kernel is locked down, ignoring table override\n");
+ return;
+ }
+
acpi_tables_addr =
memblock_find_in_range(0, ACPI_TABLE_UPGRADE_MAX_PHYS,
all_tables_size, PAGE_SIZE);
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Josh Boyer,
David Howells, Matthew Garrett, Kees Cook, Dave Young, linux-acpi
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: Josh Boyer <jwboyer@redhat.com>
This option allows userspace to pass the RSDP address to the kernel, which
makes it possible for a user to modify the workings of hardware. Reject
the option when the kernel is locked down. This requires some reworking
of the existing RSDP command line logic, since the early boot code also
makes use of a command-line passed RSDP when locating the SRAT table
before the lockdown code has been initialised. This is achieved by
separating the command line RSDP path in the early boot code from the
generic RSDP path, and then copying the command line RSDP into boot
params in the kernel proper if lockdown is not enabled. If lockdown is
enabled and an RSDP is provided on the command line, this will only be
used when parsing SRAT (which shouldn't permit kernel code execution)
and will be ignored in the rest of the kernel.
(Modified by Matthew Garrett in order to handle the early boot RSDP
environment)
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: Dave Young <dyoung@redhat.com>
cc: linux-acpi@vger.kernel.org
---
arch/x86/boot/compressed/acpi.c | 19 +++++++++++++------
arch/x86/include/asm/acpi.h | 9 +++++++++
arch/x86/include/asm/x86_init.h | 2 ++
arch/x86/kernel/acpi/boot.c | 5 +++++
arch/x86/kernel/x86_init.c | 1 +
drivers/acpi/osl.c | 14 +++++++++++++-
include/linux/acpi.h | 6 ++++++
7 files changed, 49 insertions(+), 7 deletions(-)
diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index 15255f388a85..149795c369f2 100644
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -26,7 +26,7 @@ struct mem_vector immovable_mem[MAX_NUMNODES*2];
*/
#define MAX_ADDR_LEN 19
-static acpi_physical_address get_acpi_rsdp(void)
+static acpi_physical_address get_cmdline_acpi_rsdp(void)
{
acpi_physical_address addr = 0;
@@ -278,10 +278,7 @@ acpi_physical_address get_rsdp_addr(void)
{
acpi_physical_address pa;
- pa = get_acpi_rsdp();
-
- if (!pa)
- pa = boot_params->acpi_rsdp_addr;
+ pa = boot_params->acpi_rsdp_addr;
/*
* Try to get EFI data from setup_data. This can happen when we're a
@@ -311,7 +308,17 @@ static unsigned long get_acpi_srat_table(void)
char arg[10];
u8 *entry;
- rsdp = (struct acpi_table_rsdp *)(long)boot_params->acpi_rsdp_addr;
+ /*
+ * Check whether we were given an RSDP on the command line. We don't
+ * stash this in boot params because the kernel itself may have
+ * different ideas about whether to trust a command-line parameter.
+ */
+ rsdp = (struct acpi_table_rsdp *)get_cmdline_acpi_rsdp();
+
+ if (!rsdp)
+ rsdp = (struct acpi_table_rsdp *)(long)
+ boot_params->acpi_rsdp_addr;
+
if (!rsdp)
return 0;
diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
index aac686e1e005..bc9693c9107e 100644
--- a/arch/x86/include/asm/acpi.h
+++ b/arch/x86/include/asm/acpi.h
@@ -117,6 +117,12 @@ static inline bool acpi_has_cpu_in_madt(void)
return !!acpi_lapic;
}
+#define ACPI_HAVE_ARCH_SET_ROOT_POINTER
+static inline void acpi_arch_set_root_pointer(u64 addr)
+{
+ x86_init.acpi.set_root_pointer(addr);
+}
+
#define ACPI_HAVE_ARCH_GET_ROOT_POINTER
static inline u64 acpi_arch_get_root_pointer(void)
{
@@ -125,6 +131,7 @@ static inline u64 acpi_arch_get_root_pointer(void)
void acpi_generic_reduced_hw_init(void);
+void x86_default_set_root_pointer(u64 addr);
u64 x86_default_get_root_pointer(void);
#else /* !CONFIG_ACPI */
@@ -138,6 +145,8 @@ static inline void disable_acpi(void) { }
static inline void acpi_generic_reduced_hw_init(void) { }
+static inline void x86_default_set_root_pointer(u64 addr) { }
+
static inline u64 x86_default_get_root_pointer(void)
{
return 0;
diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index ac0934189017..19435858df5f 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -134,10 +134,12 @@ struct x86_hyper_init {
/**
* struct x86_init_acpi - x86 ACPI init functions
+ * @set_root_poitner: set RSDP address
* @get_root_pointer: get RSDP address
* @reduced_hw_early_init: hardware reduced platform early init
*/
struct x86_init_acpi {
+ void (*set_root_pointer)(u64 addr);
u64 (*get_root_pointer)(void);
void (*reduced_hw_early_init)(void);
};
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 17b33ef604f3..04205ce127a1 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -1760,6 +1760,11 @@ void __init arch_reserve_mem_area(acpi_physical_address addr, size_t size)
e820__update_table_print();
}
+void x86_default_set_root_pointer(u64 addr)
+{
+ boot_params.acpi_rsdp_addr = addr;
+}
+
u64 x86_default_get_root_pointer(void)
{
return boot_params.acpi_rsdp_addr;
diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index 1bef687faf22..18a799c8fa28 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -95,6 +95,7 @@ struct x86_init_ops x86_init __initdata = {
},
.acpi = {
+ .set_root_pointer = x86_default_set_root_pointer,
.get_root_pointer = x86_default_get_root_pointer,
.reduced_hw_early_init = acpi_generic_reduced_hw_init,
},
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 9c0edf2fc0dd..d43df3a3fa8d 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -26,6 +26,7 @@
#include <linux/list.h>
#include <linux/jiffies.h>
#include <linux/semaphore.h>
+#include <linux/security.h>
#include <asm/io.h>
#include <linux/uaccess.h>
@@ -180,8 +181,19 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
acpi_physical_address pa;
#ifdef CONFIG_KEXEC
- if (acpi_rsdp)
+ /*
+ * We may have been provided with an RSDP on the command line,
+ * but if a malicious user has done so they may be pointing us
+ * at modified ACPI tables that could alter kernel behaviour -
+ * so, we check the lockdown status before making use of
+ * it. If we trust it then also stash it in an architecture
+ * specific location (if appropriate) so it can be carried
+ * over further kexec()s.
+ */
+ if (acpi_rsdp && !security_locked_down(LOCKDOWN_ACPI_TABLES)) {
+ acpi_arch_set_root_pointer(acpi_rsdp);
return acpi_rsdp;
+ }
#endif
pa = acpi_arch_get_root_pointer();
if (pa)
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index e40e1e27ed8e..6b35f2f4cab3 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -643,6 +643,12 @@ bool acpi_gtdt_c3stop(int type);
int acpi_arch_timer_mem_init(struct arch_timer_mem *timer_mem, int *timer_count);
#endif
+#ifndef ACPI_HAVE_ARCH_SET_ROOT_POINTER
+static inline void acpi_arch_set_root_pointer(u64 addr)
+{
+}
+#endif
+
#ifndef ACPI_HAVE_ARCH_GET_ROOT_POINTER
static inline u64 acpi_arch_get_root_pointer(void)
{
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 14/29] ACPI: Limit access to custom_method when the kernel is locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Matthew Garrett,
Matthew Garrett, David Howells, Kees Cook, linux-acpi
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: Matthew Garrett <mjg59@srcf.ucam.org>
custom_method effectively allows arbitrary access to system memory, making
it possible for an attacker to circumvent restrictions on module loading.
Disable it if the kernel is locked down.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: linux-acpi@vger.kernel.org
---
drivers/acpi/custom_method.c | 6 ++++++
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
3 files changed, 8 insertions(+)
diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c
index b2ef4c2ec955..7031307becd7 100644
--- a/drivers/acpi/custom_method.c
+++ b/drivers/acpi/custom_method.c
@@ -9,6 +9,7 @@
#include <linux/uaccess.h>
#include <linux/debugfs.h>
#include <linux/acpi.h>
+#include <linux/security.h>
#include "internal.h"
@@ -29,6 +30,11 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf,
struct acpi_table_header table;
acpi_status status;
+ int ret;
+
+ ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
+ if (ret)
+ return ret;
if (!(*ppos)) {
/* parse the table header to get the table length */
diff --git a/include/linux/security.h b/include/linux/security.h
index 155ff026eca4..1c32522b3c5a 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -110,6 +110,7 @@ enum lockdown_reason {
LOCKDOWN_PCI_ACCESS,
LOCKDOWN_IOPORT,
LOCKDOWN_MSR,
+ LOCKDOWN_ACPI_TABLES,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index d99c0bee739d..ecb51b1a5c03 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -25,6 +25,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_PCI_ACCESS] = "direct PCI access",
[LOCKDOWN_IOPORT] = "raw io port access",
[LOCKDOWN_MSR] = "raw MSR access",
+ [LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 13/29] x86/msr: Restrict MSR access when the kernel is locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Matthew Garrett,
Matthew Garrett, David Howells, Kees Cook, Thomas Gleixner, x86
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: Matthew Garrett <mjg59@srcf.ucam.org>
Writing to MSRs should not be allowed if the kernel is locked down, since
it could lead to execution of arbitrary code in kernel mode. Based on a
patch by Kees Cook.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
cc: x86@kernel.org
---
arch/x86/kernel/msr.c | 8 ++++++++
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
3 files changed, 10 insertions(+)
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 3db2252b958d..1547be359d7f 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -34,6 +34,7 @@
#include <linux/notifier.h>
#include <linux/uaccess.h>
#include <linux/gfp.h>
+#include <linux/security.h>
#include <asm/cpufeature.h>
#include <asm/msr.h>
@@ -79,6 +80,10 @@ static ssize_t msr_write(struct file *file, const char __user *buf,
int err = 0;
ssize_t bytes = 0;
+ err = security_locked_down(LOCKDOWN_MSR);
+ if (err)
+ return err;
+
if (count % 8)
return -EINVAL; /* Invalid chunk size */
@@ -130,6 +135,9 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
err = -EFAULT;
break;
}
+ err = security_locked_down(LOCKDOWN_MSR);
+ if (err)
+ break;
err = wrmsr_safe_regs_on_cpu(cpu, regs);
if (err)
break;
diff --git a/include/linux/security.h b/include/linux/security.h
index 79250b2ffb8f..155ff026eca4 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -109,6 +109,7 @@ enum lockdown_reason {
LOCKDOWN_HIBERNATION,
LOCKDOWN_PCI_ACCESS,
LOCKDOWN_IOPORT,
+ LOCKDOWN_MSR,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 316f7cf4e996..d99c0bee739d 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -24,6 +24,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_HIBERNATION] = "hibernation",
[LOCKDOWN_PCI_ACCESS] = "direct PCI access",
[LOCKDOWN_IOPORT] = "raw io port access",
+ [LOCKDOWN_MSR] = "raw MSR access",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 12/29] x86: Lock down IO port access when the kernel is locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Matthew Garrett,
Matthew Garrett, David Howells, Kees Cook, x86
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: Matthew Garrett <mjg59@srcf.ucam.org>
IO port access would permit users to gain access to PCI configuration
registers, which in turn (on a lot of hardware) give access to MMIO
register space. This would potentially permit root to trigger arbitrary
DMA, so lock it down by default.
This also implicitly locks down the KDADDIO, KDDELIO, KDENABIO and
KDDISABIO console ioctls.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: x86@kernel.org
---
arch/x86/kernel/ioport.c | 7 +++++--
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
3 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index 0fe1c8782208..61a89d3c0382 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -11,6 +11,7 @@
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/ioport.h>
+#include <linux/security.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/slab.h>
@@ -31,7 +32,8 @@ long ksys_ioperm(unsigned long from, unsigned long num, int turn_on)
if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
return -EINVAL;
- if (turn_on && !capable(CAP_SYS_RAWIO))
+ if (turn_on && (!capable(CAP_SYS_RAWIO) ||
+ security_locked_down(LOCKDOWN_IOPORT)))
return -EPERM;
/*
@@ -126,7 +128,8 @@ SYSCALL_DEFINE1(iopl, unsigned int, level)
return -EINVAL;
/* Trying to gain more privileges? */
if (level > old) {
- if (!capable(CAP_SYS_RAWIO))
+ if (!capable(CAP_SYS_RAWIO) ||
+ security_locked_down(LOCKDOWN_IOPORT))
return -EPERM;
}
regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) |
diff --git a/include/linux/security.h b/include/linux/security.h
index 8adbd62b7669..79250b2ffb8f 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -108,6 +108,7 @@ enum lockdown_reason {
LOCKDOWN_KEXEC,
LOCKDOWN_HIBERNATION,
LOCKDOWN_PCI_ACCESS,
+ LOCKDOWN_IOPORT,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 655fe388e615..316f7cf4e996 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -23,6 +23,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_KEXEC] = "kexec of unsigned images",
[LOCKDOWN_HIBERNATION] = "hibernation",
[LOCKDOWN_PCI_ACCESS] = "direct PCI access",
+ [LOCKDOWN_IOPORT] = "raw io port access",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 11/29] PCI: Lock down BAR access when the kernel is locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Matthew Garrett,
David Howells, Matthew Garrett, Bjorn Helgaas, Kees Cook,
linux-pci
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: Matthew Garrett <mjg59@srcf.ucam.org>
Any hardware that can potentially generate DMA has to be locked down in
order to avoid it being possible for an attacker to modify kernel code,
allowing them to circumvent disabled module loading or module signing.
Default to paranoid - in future we can potentially relax this for
sufficiently IOMMU-isolated devices.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: linux-pci@vger.kernel.org
---
drivers/pci/pci-sysfs.c | 16 ++++++++++++++++
drivers/pci/proc.c | 14 ++++++++++++--
drivers/pci/syscall.c | 4 +++-
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
5 files changed, 33 insertions(+), 3 deletions(-)
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 965c72104150..396c1a90c0e1 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -906,6 +906,11 @@ static ssize_t pci_write_config(struct file *filp, struct kobject *kobj,
unsigned int size = count;
loff_t init_off = off;
u8 *data = (u8 *) buf;
+ int ret;
+
+ ret = security_locked_down(LOCKDOWN_PCI_ACCESS);
+ if (ret)
+ return ret;
if (off > dev->cfg_size)
return 0;
@@ -1167,6 +1172,11 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
int bar = (unsigned long)attr->private;
enum pci_mmap_state mmap_type;
struct resource *res = &pdev->resource[bar];
+ int ret;
+
+ ret = security_locked_down(LOCKDOWN_PCI_ACCESS);
+ if (ret)
+ return ret;
if (res->flags & IORESOURCE_MEM && iomem_is_exclusive(res->start))
return -EINVAL;
@@ -1243,6 +1253,12 @@ static ssize_t pci_write_resource_io(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr, char *buf,
loff_t off, size_t count)
{
+ int ret;
+
+ ret = security_locked_down(LOCKDOWN_PCI_ACCESS);
+ if (ret)
+ return ret;
+
return pci_resource_io(filp, kobj, attr, buf, off, count, true);
}
diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index fe7fe678965b..5495537c60c2 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -13,6 +13,7 @@
#include <linux/seq_file.h>
#include <linux/capability.h>
#include <linux/uaccess.h>
+#include <linux/security.h>
#include <asm/byteorder.h>
#include "pci.h"
@@ -115,7 +116,11 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf,
struct pci_dev *dev = PDE_DATA(ino);
int pos = *ppos;
int size = dev->cfg_size;
- int cnt;
+ int cnt, ret;
+
+ ret = security_locked_down(LOCKDOWN_PCI_ACCESS);
+ if (ret)
+ return ret;
if (pos >= size)
return 0;
@@ -196,6 +201,10 @@ static long proc_bus_pci_ioctl(struct file *file, unsigned int cmd,
#endif /* HAVE_PCI_MMAP */
int ret = 0;
+ ret = security_locked_down(LOCKDOWN_PCI_ACCESS);
+ if (ret)
+ return ret;
+
switch (cmd) {
case PCIIOC_CONTROLLER:
ret = pci_domain_nr(dev->bus);
@@ -238,7 +247,8 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma)
struct pci_filp_private *fpriv = file->private_data;
int i, ret, write_combine = 0, res_bit = IORESOURCE_MEM;
- if (!capable(CAP_SYS_RAWIO))
+ if (!capable(CAP_SYS_RAWIO) ||
+ security_locked_down(LOCKDOWN_PCI_ACCESS))
return -EPERM;
if (fpriv->mmap_state == pci_mmap_io) {
diff --git a/drivers/pci/syscall.c b/drivers/pci/syscall.c
index d96626c614f5..31e39558d49d 100644
--- a/drivers/pci/syscall.c
+++ b/drivers/pci/syscall.c
@@ -7,6 +7,7 @@
#include <linux/errno.h>
#include <linux/pci.h>
+#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include "pci.h"
@@ -90,7 +91,8 @@ SYSCALL_DEFINE5(pciconfig_write, unsigned long, bus, unsigned long, dfn,
u32 dword;
int err = 0;
- if (!capable(CAP_SYS_ADMIN))
+ if (!capable(CAP_SYS_ADMIN) ||
+ security_locked_down(LOCKDOWN_PCI_ACCESS))
return -EPERM;
dev = pci_get_domain_bus_and_slot(0, bus, dfn);
diff --git a/include/linux/security.h b/include/linux/security.h
index 304a155a5628..8adbd62b7669 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -107,6 +107,7 @@ enum lockdown_reason {
LOCKDOWN_DEV_MEM,
LOCKDOWN_KEXEC,
LOCKDOWN_HIBERNATION,
+ LOCKDOWN_PCI_ACCESS,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index a0996f75629f..655fe388e615 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -22,6 +22,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
[LOCKDOWN_KEXEC] = "kexec of unsigned images",
[LOCKDOWN_HIBERNATION] = "hibernation",
+ [LOCKDOWN_PCI_ACCESS] = "direct PCI access",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 10/29] hibernate: Disable when the kernel is locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Josh Boyer,
David Howells, Matthew Garrett, Kees Cook, rjw, pavel, linux-pm
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: Josh Boyer <jwboyer@fedoraproject.org>
There is currently no way to verify the resume image when returning
from hibernate. This might compromise the signed modules trust model,
so until we can work with signed hibernate images we disable it when the
kernel is locked down.
Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: rjw@rjwysocki.net
Cc: pavel@ucw.cz
cc: linux-pm@vger.kernel.org
---
include/linux/security.h | 1 +
kernel/power/hibernate.c | 3 ++-
security/lockdown/lockdown.c | 1 +
3 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/include/linux/security.h b/include/linux/security.h
index 69c5de539e9a..304a155a5628 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -106,6 +106,7 @@ enum lockdown_reason {
LOCKDOWN_MODULE_SIGNATURE,
LOCKDOWN_DEV_MEM,
LOCKDOWN_KEXEC,
+ LOCKDOWN_HIBERNATION,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index cd7434e6000d..3c0a5a8170b0 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -30,6 +30,7 @@
#include <linux/ctype.h>
#include <linux/genhd.h>
#include <linux/ktime.h>
+#include <linux/security.h>
#include <trace/events/power.h>
#include "power.h"
@@ -68,7 +69,7 @@ static const struct platform_hibernation_ops *hibernation_ops;
bool hibernation_available(void)
{
- return (nohibernate == 0);
+ return nohibernate == 0 && !security_locked_down(LOCKDOWN_HIBERNATION);
}
/**
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 6f302c156bc8..a0996f75629f 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -21,6 +21,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
[LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
[LOCKDOWN_KEXEC] = "kexec of unsigned images",
+ [LOCKDOWN_HIBERNATION] = "hibernation",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 09/29] kexec_file: Restrict at runtime if the kernel is locked down
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Jiri Bohac,
David Howells, Matthew Garrett, Kees Cook, kexec
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>
From: Jiri Bohac <jbohac@suse.cz>
When KEXEC_SIG is not enabled, kernel should not load images through
kexec_file systemcall if the kernel is locked down.
[Modified by David Howells to fit with modifications to the previous patch
and to return -EPERM if the kernel is locked down for consistency with
other lockdowns. Modified by Matthew Garrett to remove the IMA
integration, which will be replaced by integrating with the IMA
architecture policy patches.]
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Jiri Bohac <jbohac@suse.cz>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: kexec@lists.infradead.org
---
kernel/kexec_file.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 875482c34154..dd06f1070d66 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -228,7 +228,10 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
goto out;
}
- ret = 0;
+ ret = security_locked_down(LOCKDOWN_KEXEC);
+ if (ret)
+ goto out;
+
break;
/* All other errors are fatal, including nomem, unparseable
--
2.22.0.770.g0f2c4a37fd-goog
^ permalink raw reply related
* [PATCH V38 08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE
From: Matthew Garrett @ 2019-08-08 0:07 UTC (permalink / raw)
To: jmorris-gx6/JNMH7DfYtjvyW6yDsg
Cc: Jiri Bohac, linux-api-u79uwXL29TY76Z2rM5mHXA,
kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
linux-kernel-u79uwXL29TY76Z2rM5mHXA, Matthew Garrett,
David Howells, linux-security-module-u79uwXL29TY76Z2rM5mHXA,
Dave Young
In-Reply-To: <20190808000721.124691-1-matthewgarrett-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
From: Jiri Bohac <jbohac-AlSwsSmVLrQ@public.gmane.org>
This is a preparatory patch for kexec_file_load() lockdown. A locked down
kernel needs to prevent unsigned kernel images from being loaded with
kexec_file_load(). Currently, the only way to force the signature
verification is compiling with KEXEC_VERIFY_SIG. This prevents loading
usigned images even when the kernel is not locked down at runtime.
This patch splits KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE.
Analogous to the MODULE_SIG and MODULE_SIG_FORCE for modules, KEXEC_SIG
turns on the signature verification but allows unsigned images to be
loaded. KEXEC_SIG_FORCE disallows images without a valid signature.
Signed-off-by: Jiri Bohac <jbohac-AlSwsSmVLrQ@public.gmane.org>
Signed-off-by: David Howells <dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Matthew Garrett <mjg59-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Reviewed-by: Jiri Bohac <jbohac-AlSwsSmVLrQ@public.gmane.org>
Reviewed-by: Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
cc: kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
---
arch/x86/Kconfig | 20 +++++++++----
crypto/asymmetric_keys/verify_pefile.c | 4 ++-
include/linux/kexec.h | 4 +--
kernel/kexec_file.c | 41 ++++++++++++++++++++++----
4 files changed, 55 insertions(+), 14 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 05e78acb187c..fd2cd4f861cc 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2032,20 +2032,30 @@ config KEXEC_FILE
config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE
-config KEXEC_VERIFY_SIG
+config KEXEC_SIG
bool "Verify kernel signature during kexec_file_load() syscall"
depends on KEXEC_FILE
---help---
- This option makes kernel signature verification mandatory for
- the kexec_file_load() syscall.
- In addition to that option, you need to enable signature
+ This option makes the kexec_file_load() syscall check for a valid
+ signature of the kernel image. The image can still be loaded without
+ a valid signature unless you also enable KEXEC_SIG_FORCE, though if
+ there's a signature that we can check, then it must be valid.
+
+ In addition to this option, you need to enable signature
verification for the corresponding kernel image type being
loaded in order for this to work.
+config KEXEC_SIG_FORCE
+ bool "Require a valid signature in kexec_file_load() syscall"
+ depends on KEXEC_SIG
+ ---help---
+ This option makes kernel signature verification mandatory for
+ the kexec_file_load() syscall.
+
config KEXEC_BZIMAGE_VERIFY_SIG
bool "Enable bzImage signature verification support"
- depends on KEXEC_VERIFY_SIG
+ depends on KEXEC_SIG
depends on SIGNED_PE_FILE_VERIFICATION
select SYSTEM_TRUSTED_KEYRING
---help---
diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c
index 3b303fe2f061..cc9dbcecaaca 100644
--- a/crypto/asymmetric_keys/verify_pefile.c
+++ b/crypto/asymmetric_keys/verify_pefile.c
@@ -96,7 +96,7 @@ static int pefile_parse_binary(const void *pebuf, unsigned int pelen,
if (!ddir->certs.virtual_address || !ddir->certs.size) {
pr_debug("Unsigned PE binary\n");
- return -EKEYREJECTED;
+ return -ENODATA;
}
chkaddr(ctx->header_size, ddir->certs.virtual_address,
@@ -403,6 +403,8 @@ static int pefile_digest_pe(const void *pebuf, unsigned int pelen,
* (*) 0 if at least one signature chain intersects with the keys in the trust
* keyring, or:
*
+ * (*) -ENODATA if there is no signature present.
+ *
* (*) -ENOPKG if a suitable crypto module couldn't be found for a check on a
* chain.
*
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 305f6a5ca4fe..998f77c3a0e1 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -125,7 +125,7 @@ typedef void *(kexec_load_t)(struct kimage *image, char *kernel_buf,
unsigned long cmdline_len);
typedef int (kexec_cleanup_t)(void *loader_data);
-#ifdef CONFIG_KEXEC_VERIFY_SIG
+#ifdef CONFIG_KEXEC_SIG
typedef int (kexec_verify_sig_t)(const char *kernel_buf,
unsigned long kernel_len);
#endif
@@ -134,7 +134,7 @@ struct kexec_file_ops {
kexec_probe_t *probe;
kexec_load_t *load;
kexec_cleanup_t *cleanup;
-#ifdef CONFIG_KEXEC_VERIFY_SIG
+#ifdef CONFIG_KEXEC_SIG
kexec_verify_sig_t *verify_sig;
#endif
};
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b8cc032d5620..875482c34154 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -88,7 +88,7 @@ int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
return kexec_image_post_load_cleanup_default(image);
}
-#ifdef CONFIG_KEXEC_VERIFY_SIG
+#ifdef CONFIG_KEXEC_SIG
static int kexec_image_verify_sig_default(struct kimage *image, void *buf,
unsigned long buf_len)
{
@@ -186,7 +186,8 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
const char __user *cmdline_ptr,
unsigned long cmdline_len, unsigned flags)
{
- int ret = 0;
+ const char *reason;
+ int ret;
void *ldata;
loff_t size;
@@ -202,14 +203,42 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
if (ret)
goto out;
-#ifdef CONFIG_KEXEC_VERIFY_SIG
+#ifdef CONFIG_KEXEC_SIG
ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
image->kernel_buf_len);
- if (ret) {
- pr_debug("kernel signature verification failed.\n");
+ switch (ret) {
+ case 0:
+ break;
+
+ /* Certain verification errors are non-fatal if we're not
+ * checking errors, provided we aren't mandating that there
+ * must be a valid signature.
+ */
+ case -ENODATA:
+ reason = "kexec of unsigned image";
+ goto decide;
+ case -ENOPKG:
+ reason = "kexec of image with unsupported crypto";
+ goto decide;
+ case -ENOKEY:
+ reason = "kexec of image with unavailable key";
+ decide:
+ if (IS_ENABLED(CONFIG_KEXEC_SIG_FORCE)) {
+ pr_notice("%s rejected\n", reason);
+ goto out;
+ }
+
+ ret = 0;
+ break;
+
+ /* All other errors are fatal, including nomem, unparseable
+ * signatures and signature check failures - even if signatures
+ * aren't required.
+ */
+ default:
+ pr_notice("kernel signature verification failed (%d).\n", ret);
goto out;
}
- pr_debug("kernel signature verification successful.\n");
#endif
/* It is possible that there no initramfs is being loaded */
if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
--
2.22.0.770.g0f2c4a37fd-goog
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