Commit graph

317 commits

Author SHA1 Message Date
Linus Torvalds
dffb641bea selinux/stable-6.17 PR 20250725
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Merge tag 'selinux-pr-20250725' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:

 - Introduce the concept of a SELinux "neveraudit" type which prevents
   all auditing of the given type/domain.

   Taken by itself, the benefit of marking a SELinux domain with the
   "neveraudit" tag is likely not very interesting, especially given the
   significant overlap with the "dontaudit" tag.

   However, given that the "neveraudit" tag applies to *all* auditing of
   the tagged domain, we can do some fairly interesting optimizations
   when a SELinux domain is marked as both "permissive" and "dontaudit"
   (think of the unconfined_t domain).

   While this pull request includes optimized inode permission and
   getattr hooks, these optimizations require SELinux policy changes,
   therefore the improvements may not be visible on standard downstream
   Linux distos for a period of time.

 - Continue the deprecation process of /sys/fs/selinux/user.

   After removing the associated userspace code in 2020, we marked the
   /sys/fs/selinux/user interface as deprecated in Linux v6.13 with
   pr_warn() and the usual documention update.

   This adds a five second sleep after the pr_warn(), following a
   previous deprecation process pattern that has worked well for us in
   the past in helping identify any existing users that we haven't yet
   reached.

 - Add a __GFP_NOWARN flag to our initial hash table allocation.

   Fuzzers such a syzbot often attempt abnormally large SELinux policy
   loads, which the SELinux code gracefully handles by checking for
   allocation failures, but not before the allocator emits a warning
   which causes the automated fuzzing to flag this as an error and
   report it to the list. While we want to continue to support the work
   done by the fuzzing teams, we want to focus on proper issues and not
   an error case that is already handled safely. Add a NOWARN flag to
   quiet the allocator and prevent syzbot from tripping on this again.

 - Remove some unnecessary selinuxfs cleanup code, courtesy of Al.

 - Update the SELinux in-kernel documentation with pointers to
   additional information.

* tag 'selinux-pr-20250725' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: don't bother with selinuxfs_info_free() on failures
  selinux: add __GFP_NOWARN to hashtab_init() allocations
  selinux: optimize selinux_inode_getattr/permission() based on neveraudit|permissive
  selinux: introduce neveraudit types
  documentation: add links to SELinux resources
  selinux: add a 5 second sleep to /sys/fs/selinux/user
2025-07-28 18:25:57 -07:00
Stephen Smalley
1106896146 selinux: introduce neveraudit types
Introduce neveraudit types i.e. types that should never trigger
audit messages. This allows the AVC to skip all audit-related
processing for such types. Note that neveraudit differs from
dontaudit not only wrt being applied for all checks with a given
source type but also in that it disables all auditing, not just
permission denials.

When a type is both a permissive type and a neveraudit type,
the security server can short-circuit the security_compute_av()
logic, allowing all permissions and not auditing any permissions.

This change just introduces the basic support but does not yet
further optimize the AVC or hook function logic when a type
is both a permissive type and a dontaudit type.

Suggested-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2025-06-19 17:23:04 -04:00
Stephen Smalley
fde46f60f6 selinux: change security_compute_sid to return the ssid or tsid on match
If the end result of a security_compute_sid() computation matches the
ssid or tsid, return that SID rather than looking it up again. This
avoids the problem of multiple initial SIDs that map to the same
context.

Cc: stable@vger.kernel.org
Reported-by: Guido Trentalancia <guido@trentalancia.com>
Fixes: ae254858ce ("selinux: introduce an initial SID for early boot processes")
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Tested-by: Guido Trentalancia <guido@trentalancia.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2025-06-19 16:13:16 -04:00
Paul Moore
1ec31f14a8 selinux: remove a duplicated include
The "linux/parser.h" header was included twice, we only need it once.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202504121945.Q0GDD0sG-lkp@intel.com/
Signed-off-by: Paul Moore <paul@paul-moore.com>
2025-04-12 11:31:46 -04:00
Takaya Saeki
8716451a4e selinux: support wildcard match in genfscon
Currently, genfscon only supports string prefix match to label files.
Thus, labeling numerous dynamic sysfs entries requires many specific
path rules. For example, labeling device paths such as
`/sys/devices/pci0000:00/0000:00:03.1/<...>/0000:04:00.1/wakeup`
requires listing all specific PCI paths, which is challenging to
maintain. While user-space restorecon can handle these paths with
regular expression rules, relabeling thousands of paths under sysfs
after it is mounted is inefficient compared to using genfscon.

This commit adds wildcard matching to genfscon to make rules more
efficient and expressive. This new behavior is enabled by
genfs_seclabel_wildcard capability. With this capability, genfscon does
wildcard matching instead of prefix matching. When multiple wildcard
rules match against a path, then the longest rule (determined by the
length of the rule string) will be applied. If multiple rules of the
same length match, the first matching rule encountered in the given
genfscon policy will be applied. Users are encouraged to write longer,
more explicit path rules to avoid relying on this behavior.

This change resulted in nice real-world performance improvements. For
example, boot times on test Android devices were reduced by 15%. This
improvement is due to the elimination of the "restorecon -R /sys" step
during boot, which takes more than two seconds in the worst case.

Signed-off-by: Takaya Saeki <takayas@chromium.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2025-04-11 16:36:34 -04:00
Christian Göttsche
47a1a15645 selinux: constify network address pointer
The network address, either an IPv4 or IPv6 one, is not modified.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2025-04-11 16:29:50 -04:00
Christian Göttsche
a3d3043ef2 selinux: get netif_wildcard policycap from policy instead of cache
Retrieve the netif_wildcard policy capability in security_netif_sid()
from the locked active policy instead of the cached value in
selinux_state.

Fixes: 8af43b61c1 ("selinux: support wildcard network interface names")
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
[PM: /netlabel/netif/ due to a typo in the description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2025-03-17 16:22:04 -04:00
Christian Göttsche
8af43b61c1 selinux: support wildcard network interface names
Add support for wildcard matching of network interface names.  This is
useful for auto-generated interfaces, for example podman creates network
interfaces for containers with the naming scheme podman0, podman1,
podman2, ...

To maintain backward compatibility guard this feature with a new policy
capability 'netif_wildcard'.

Netifcon definitions are compared against in the order given by the
policy, so userspace tools should sort them in a reasonable order.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2025-03-07 15:11:10 -05:00
Linus Torvalds
690ffcd817 selinux/stable-6.14 PR 20250121
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Merge tag 'selinux-pr-20250121' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:

 - Extended permissions supported in conditional policy

   The SELinux extended permissions, aka "xperms", allow security admins
   to target individuals ioctls, and recently netlink messages, with
   their SELinux policy. Adding support for conditional policies allows
   admins to toggle the granular xperms using SELinux booleans, helping
   pave the way for greater use of xperms in general purpose SELinux
   policies. This change bumps the maximum SELinux policy version to 34.

 - Fix a SCTP/SELinux error return code inconsistency

   Depending on the loaded SELinux policy, specifically it's
   EXTSOCKCLASS support, the bind(2) LSM/SELinux hook could return
   different error codes due to the SELinux code checking the socket's
   SELinux object class (which can vary depending on EXTSOCKCLASS) and
   not the socket's sk_protocol field. We fix this by doing the obvious,
   and looking at the sock->sk_protocol field instead of the object
   class.

 - Makefile fixes to properly cleanup av_permissions.h

   Add av_permissions.h to "targets" so that it is properly cleaned up
   using the kbuild infrastructure.

 - A number of smaller improvements by Christian Göttsche

   A variety of straightforward changes to reduce code duplication,
   reduce pointer lookups, migrate void pointers to defined types,
   simplify code, constify function parameters, and correct iterator
   types.

* tag 'selinux-pr-20250121' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: make more use of str_read() when loading the policy
  selinux: avoid unnecessary indirection in struct level_datum
  selinux: use known type instead of void pointer
  selinux: rename comparison functions for clarity
  selinux: rework match_ipv6_addrmask()
  selinux: constify and reconcile function parameter names
  selinux: avoid using types indicating user space interaction
  selinux: supply missing field initializers
  selinux: add netlink nlmsg_type audit message
  selinux: add support for xperms in conditional policies
  selinux: Fix SCTP error inconsistency in selinux_socket_bind()
  selinux: use native iterator types
  selinux: add generated av_permissions.h to targets
2025-01-21 20:09:14 -08:00
Christian Göttsche
83e7e18eed selinux: rename comparison functions for clarity
The functions context_cmp(), mls_context_cmp() and ebitmap_cmp() are not
traditional C style compare functions returning -1, 0, and 1 for less
than, equal, and greater than; they only return whether their arguments
are equal.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2025-01-07 23:14:39 -05:00
Christian Göttsche
5e99b81f48 selinux: rework match_ipv6_addrmask()
Constify parameters, add size hints, and simplify control flow.

According to godbolt the same assembly is generated.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2025-01-07 23:14:38 -05:00
Christian Göttsche
9090308510 selinux: constify and reconcile function parameter names
Align the parameter names between declarations and definitions, and
constify read-only parameters.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: tweak the subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2025-01-07 23:14:38 -05:00
Thiébaud Weksteen
5e7f0efd23 selinux: match extended permissions to their base permissions
In commit d1d991efaf ("selinux: Add netlink xperm support") a new
extended permission was added ("nlmsg"). This was the second extended
permission implemented in selinux ("ioctl" being the first one).

Extended permissions are associated with a base permission. It was found
that, in the access vector cache (avc), the extended permission did not
keep track of its base permission. This is an issue for a domain that is
using both extended permissions (i.e., a domain calling ioctl() on a
netlink socket). In this case, the extended permissions were
overlapping.

Keep track of the base permission in the cache. A new field "base_perm"
is added to struct extended_perms_decision to make sure that the
extended permission refers to the correct policy permission. A new field
"base_perms" is added to struct extended_perms to quickly decide if
extended permissions apply.

While it is in theory possible to retrieve the base permission from the
access vector, the same base permission may not be mapped to the same
bit for each class (e.g., "nlmsg" is mapped to a different bit for
"netlink_route_socket" and "netlink_audit_socket"). Instead, use a
constant (AVC_EXT_IOCTL or AVC_EXT_NLMSG) provided by the caller.

Fixes: d1d991efaf ("selinux: Add netlink xperm support")
Signed-off-by: Thiébaud Weksteen <tweek@google.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2025-01-04 20:58:46 -05:00
Thiébaud Weksteen
900f83cf37 selinux: ignore unknown extended permissions
When evaluating extended permissions, ignore unknown permissions instead
of calling BUG(). This commit ensures that future permissions can be
added without interfering with older kernels.

Cc: stable@vger.kernel.org
Fixes: fa1aa143ac ("selinux: extended permissions for ioctls")
Signed-off-by: Thiébaud Weksteen <tweek@google.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-12-15 21:59:03 -05:00
Christian Göttsche
4aa1761934 selinux: add support for xperms in conditional policies
Add support for extended permission rules in conditional policies.
Currently the kernel accepts such rules already, but evaluating a
security decision will hit a BUG() in
services_compute_xperms_decision().  Thus reject extended permission
rules in conditional policies for current policy versions.

Add a new policy version for this feature.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Tested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-12-13 16:35:38 -05:00
Linus Torvalds
5591fd5e03 lsm/stable-6.13 PR 20241112
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Merge tag 'lsm-pr-20241112' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

Pull lsm updates from Paul Moore:
 "Thirteen patches, all focused on moving away from the current 'secid'
  LSM identifier to a richer 'lsm_prop' structure.

  This move will help reduce the translation that is necessary in many
  LSMs, offering better performance, and make it easier to support
  different LSMs in the future"

* tag 'lsm-pr-20241112' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
  lsm: remove lsm_prop scaffolding
  netlabel,smack: use lsm_prop for audit data
  audit: change context data from secid to lsm_prop
  lsm: create new security_cred_getlsmprop LSM hook
  audit: use an lsm_prop in audit_names
  lsm: use lsm_prop in security_inode_getsecid
  lsm: use lsm_prop in security_current_getsecid
  audit: update shutdown LSM data
  lsm: use lsm_prop in security_ipc_getsecid
  audit: maintain an lsm_prop in audit_context
  lsm: add lsmprop_to_secctx hook
  lsm: use lsm_prop in security_audit_rule_match
  lsm: add the lsm_prop data structure
2024-11-18 17:34:05 -08:00
Casey Schaufler
8afd8c8faa lsm: remove lsm_prop scaffolding
Remove the scaffold member from the lsm_prop. Remove the
remaining places it is being set.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: subj line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-10-11 14:34:16 -04:00
Casey Schaufler
870b7fdc66 lsm: use lsm_prop in security_audit_rule_match
Change the secid parameter of security_audit_rule_match
to a lsm_prop structure pointer. Pass the entry from the
lsm_prop structure for the approprite slot to the LSM hook.

Change the users of security_audit_rule_match to use the
lsm_prop instead of a u32. The scaffolding function lsmprop_init()
fills the structure with the value of the old secid, ensuring that
it is available to the appropriate module hook. The sources of
the secid, security_task_getsecid() and security_inode_getsecid(),
will be converted to use the lsm_prop structure later in the series.
At that point the use of lsmprop_init() is dropped.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-10-11 14:34:12 -04:00
Thiébaud Weksteen
d1d991efaf selinux: Add netlink xperm support
Reuse the existing extended permissions infrastructure to support
policies based on the netlink message types.

A new policy capability "netlink_xperm" is introduced. When disabled,
the previous behaviour is preserved. That is, netlink_send will rely on
the permission mappings defined in nlmsgtab.c (e.g, nlmsg_read for
RTM_GETADDR on NETLINK_ROUTE). When enabled, the mappings are ignored
and the generic "nlmsg" permission is used instead.

The new "nlmsg" permission is an extended permission. The 16 bits of the
extended permission are mapped to the nlmsg_type field.

Example policy on Android, preventing regular apps from accessing the
device's MAC address and ARP table, but allowing this access to
privileged apps, looks as follows:

allow netdomain self:netlink_route_socket {
	create read getattr write setattr lock append connect getopt
	setopt shutdown nlmsg
};
allowxperm netdomain self:netlink_route_socket nlmsg ~{
	RTM_GETLINK RTM_GETNEIGH RTM_GETNEIGHTBL
};
allowxperm priv_app self:netlink_route_socket nlmsg {
	RTM_GETLINK RTM_GETNEIGH RTM_GETNEIGHTBL
};

The constants in the example above (e.g., RTM_GETLINK) are explicitly
defined in the policy.

It is possible to generate policies to support kernels that may or
may not have the capability enabled by generating a rule for each
scenario. For instance:

allow domain self:netlink_audit_socket nlmsg_read;
allow domain self:netlink_audit_socket nlmsg;
allowxperm domain self:netlink_audit_socket nlmsg { AUDIT_GET };

The approach of defining a new permission ("nlmsg") instead of relying
on the existing permissions (e.g., "nlmsg_read", "nlmsg_readpriv" or
"nlmsg_tty_audit") has been preferred because:
  1. This is similar to the other extended permission ("ioctl");
  2. With the new extended permission, the coarse-grained mapping is not
     necessary anymore. It could eventually be removed, which would be
     impossible if the extended permission was defined below these.
  3. Having a single extra extended permission considerably simplifies
     the implementation here and in libselinux.

Signed-off-by: Thiébaud Weksteen <tweek@google.com>
Signed-off-by: Bram Bonné <brambonne@google.com>
[PM: manual merge fixes for sock_skip_has_perm()]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-10-07 16:28:11 -04:00
Canfeng Guo
da2d41308c selinux: Streamline type determination in security_compute_sid
Simplifies the logic for determining the security context type in
security_compute_sid, enhancing readability and efficiency.

Consolidates default type assignment logic next to type transition
checks, removing redundancy and improving code flow.

Signed-off-by: Canfeng Guo <guocanfeng@uniontech.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-07-29 16:34:00 -04:00
GUO Zihua
9a95c5bfbf ima: Avoid blocking in RCU read-side critical section
A panic happens in ima_match_policy:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
PGD 42f873067 P4D 0
Oops: 0000 [#1] SMP NOPTI
CPU: 5 PID: 1286325 Comm: kubeletmonit.sh
Kdump: loaded Tainted: P
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
               BIOS 0.0.0 02/06/2015
RIP: 0010:ima_match_policy+0x84/0x450
Code: 49 89 fc 41 89 cf 31 ed 89 44 24 14 eb 1c 44 39
      7b 18 74 26 41 83 ff 05 74 20 48 8b 1b 48 3b 1d
      f2 b9 f4 00 0f 84 9c 01 00 00 <44> 85 73 10 74 ea
      44 8b 6b 14 41 f6 c5 01 75 d4 41 f6 c5 02 74 0f
RSP: 0018:ff71570009e07a80 EFLAGS: 00010207
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000200
RDX: ffffffffad8dc7c0 RSI: 0000000024924925 RDI: ff3e27850dea2000
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffffabfce739
R10: ff3e27810cc42400 R11: 0000000000000000 R12: ff3e2781825ef970
R13: 00000000ff3e2785 R14: 000000000000000c R15: 0000000000000001
FS:  00007f5195b51740(0000)
GS:ff3e278b12d40000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000010 CR3: 0000000626d24002 CR4: 0000000000361ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ima_get_action+0x22/0x30
 process_measurement+0xb0/0x830
 ? page_add_file_rmap+0x15/0x170
 ? alloc_set_pte+0x269/0x4c0
 ? prep_new_page+0x81/0x140
 ? simple_xattr_get+0x75/0xa0
 ? selinux_file_open+0x9d/0xf0
 ima_file_check+0x64/0x90
 path_openat+0x571/0x1720
 do_filp_open+0x9b/0x110
 ? page_counter_try_charge+0x57/0xc0
 ? files_cgroup_alloc_fd+0x38/0x60
 ? __alloc_fd+0xd4/0x250
 ? do_sys_open+0x1bd/0x250
 do_sys_open+0x1bd/0x250
 do_syscall_64+0x5d/0x1d0
 entry_SYSCALL_64_after_hwframe+0x65/0xca

Commit c7423dbdbc ("ima: Handle -ESTALE returned by
ima_filter_rule_match()") introduced call to ima_lsm_copy_rule within a
RCU read-side critical section which contains kmalloc with GFP_KERNEL.
This implies a possible sleep and violates limitations of RCU read-side
critical sections on non-PREEMPT systems.

Sleeping within RCU read-side critical section might cause
synchronize_rcu() returning early and break RCU protection, allowing a
UAF to happen.

The root cause of this issue could be described as follows:
|	Thread A	|	Thread B	|
|			|ima_match_policy	|
|			|  rcu_read_lock	|
|ima_lsm_update_rule	|			|
|  synchronize_rcu	|			|
|			|    kmalloc(GFP_KERNEL)|
|			|      sleep		|
==> synchronize_rcu returns early
|  kfree(entry)		|			|
|			|    entry = entry->next|
==> UAF happens and entry now becomes NULL (or could be anything).
|			|    entry->action	|
==> Accessing entry might cause panic.

To fix this issue, we are converting all kmalloc that is called within
RCU read-side critical section to use GFP_ATOMIC.

Fixes: c7423dbdbc ("ima: Handle -ESTALE returned by ima_filter_rule_match()")
Cc: stable@vger.kernel.org
Signed-off-by: GUO Zihua <guozihua@huawei.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-06-13 14:26:50 -04:00
Christian Göttsche
851541709a selinux: avoid printk_ratelimit()
The usage of printk_ratelimit() is discouraged, see
include/linux/printk.h, thus use pr_warn_ratelimited().

While editing this line address the following checkpatch warning:

    WARNING: Integer promotion: Using 'h' in '%hu' is unnecessary

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-04-30 19:01:04 -04:00
Ondrej Mosnacek
ae254858ce selinux: introduce an initial SID for early boot processes
Currently, SELinux doesn't allow distinguishing between kernel threads
and userspace processes that are started before the policy is first
loaded - both get the label corresponding to the kernel SID. The only
way a process that persists from early boot can get a meaningful label
is by doing a voluntary dyntransition or re-executing itself.

Reusing the kernel label for userspace processes is problematic for
several reasons:
1. The kernel is considered to be a privileged domain and generally
   needs to have a wide range of permissions allowed to work correctly,
   which prevents the policy writer from effectively hardening against
   early boot processes that might remain running unintentionally after
   the policy is loaded (they represent a potential extra attack surface
   that should be mitigated).
2. Despite the kernel being treated as a privileged domain, the policy
   writer may want to impose certain special limitations on kernel
   threads that may conflict with the requirements of intentional early
   boot processes. For example, it is a good hardening practice to limit
   what executables the kernel can execute as usermode helpers and to
   confine the resulting usermode helper processes. However, a
   (legitimate) process surviving from early boot may need to execute a
   different set of executables.
3. As currently implemented, overlayfs remembers the security context of
   the process that created an overlayfs mount and uses it to bound
   subsequent operations on files using this context. If an overlayfs
   mount is created before the SELinux policy is loaded, these "mounter"
   checks are made against the kernel context, which may clash with
   restrictions on the kernel domain (see 2.).

To resolve this, introduce a new initial SID (reusing the slot of the
former "init" initial SID) that will be assigned to any userspace
process started before the policy is first loaded. This is easy to do,
as we can simply label any process that goes through the
bprm_creds_for_exec LSM hook with the new init-SID instead of
propagating the kernel SID from the parent.

To provide backwards compatibility for existing policies that are
unaware of this new semantic of the "init" initial SID, introduce a new
policy capability "userspace_initial_context" and set the "init" SID to
the same context as the "kernel" SID unless this capability is set by
the policy.

Another small backwards compatibility measure is needed in
security_sid_to_context_core() for before the initial SELinux policy
load - see the code comment for explanation.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
[PM: edited comments based on feedback/discussion]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-11-21 18:39:59 -05:00
Christian Göttsche
aa4b605182 selinux: make left shifts well defined
The loops upper bound represent the number of permissions used (for the
current class or in general).  The limit for this is 32, thus we might
left shift of one less, 31.  Shifting a base of 1 results in undefined
behavior; use (u32)1 as base.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-08-09 19:07:48 -04:00
Christian Göttsche
002903e1d1 selinux: update type for number of class permissions in services code
Security classes have only up to 32 permissions, hence using an u16 is
sufficient (while improving padding in struct selinux_mapping).

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-08-09 19:07:48 -04:00
Christian Göttsche
c50e125d05 selinux: avoid implicit conversions in services code
Use u32 as the output parameter type in security_get_classes() and
security_get_permissions(), based on the type of the symtab nprim
member.

Declare the read-only class string parameter of
security_get_permissions() const.

Avoid several implicit conversions by using the identical type for the
destination.

Use the type identical to the source for local variables.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: cleanup extra whitespace in subject]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-08-03 22:19:57 -04:00
Stephen Smalley
0fe53224bf selinux: update my email address
Update my email address; MAINTAINERS was updated some time ago.

Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-19 11:27:02 -04:00
Christian Göttsche
08a12b39e2 selinux: drop avtab_search()
avtab_search() shares the same logic with avtab_search_node(), except
that it returns, if found, a pointer to the struct avtab_node member
datum instead of the node itself.  Since the member is an embedded
struct, and not a pointer, the returned value of avtab_search() and
avtab_search_node() will always in unison either be NULL or non-NULL.

Drop avtab_search() and replace its calls by avtab_search_node() to
deduplicate logic and adopt the only caller caring for the type of
the returned value accordingly.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-19 11:04:28 -04:00
Christian Göttsche
7128578c79 selinux: use consistent type for AV rule specifier
The specifier for avtab keys is always supplied with a type of u16,
either as a macro to security_compute_sid() or the member specified of
the struct avtab_key.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-18 18:29:49 -04:00
Paul Moore
c52df19e37 selinux: small cleanups in selinux_audit_rule_init()
A few small tweaks to selinux_audit_rule_init():

- Adjust how we use the @rc variable so we are not doing any extra
  work in the common/success case.

- Related to the above, rework the 'out' jump label so that the
  success and error paths are different, simplifying both.

- Cleanup some of the vertical whitespace while we are making the
  other changes.

Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-05-08 16:53:41 -04:00
Christian Göttsche
3d9047a064 selinux: adjust typos in comments
Found by codespell(1)

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-05-08 16:44:01 -04:00
Stephen Smalley
e67b79850f selinux: stop passing selinux_state pointers and their offspring
Linus observed that the pervasive passing of selinux_state pointers
introduced by me in commit aa8e712cee ("selinux: wrap global selinux
state") adds overhead and complexity without providing any
benefit. The original idea was to pave the way for SELinux namespaces
but those have not yet been implemented and there isn't currently
a concrete plan to do so. Remove the passing of the selinux_state
pointers, reverting to direct use of the single global selinux_state,
and likewise remove passing of child pointers like the selinux_avc.
The selinux_policy pointer remains as it is needed for atomic switching
of policies.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202303101057.mZ3Gv5fK-lkp@intel.com/
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-03-14 15:22:45 -04:00
Linus Torvalds
57888f7b95 selinux/stable-6.2 PR 20221212
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Merge tag 'selinux-pr-20221212' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "Two SELinux patches: one increases the sleep time on deprecated
  functionality, and one removes the indirect calls in the sidtab
  context conversion code"

* tag 'selinux-pr-20221212' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: remove the sidtab context conversion indirect calls
  selinux: increase the deprecation sleep for checkreqprot and runtime disable
2022-12-13 09:32:05 -08:00
Paul Moore
048be15649 selinux: remove the sidtab context conversion indirect calls
The sidtab conversion code has support for multiple context
conversion routines through the use of function pointers and
indirect calls.  However, the reality is that all current users rely
on the same conversion routine: convert_context().  This patch does
away with this extra complexity and replaces the indirect calls
with direct function calls; allowing us to remove a layer of
obfuscation and create cleaner, more maintainable code.

Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-11-09 11:00:49 -05:00
GONG, Ruiqi
abe3c63144 selinux: enable use of both GFP_KERNEL and GFP_ATOMIC in convert_context()
The following warning was triggered on a hardware environment:

  SELinux: Converting 162 SID table entries...
  BUG: sleeping function called from invalid context at
       __might_sleep+0x60/0x74 0x0
  in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 5943, name: tar
  CPU: 7 PID: 5943 Comm: tar Tainted: P O 5.10.0 #1
  Call trace:
   dump_backtrace+0x0/0x1c8
   show_stack+0x18/0x28
   dump_stack+0xe8/0x15c
   ___might_sleep+0x168/0x17c
   __might_sleep+0x60/0x74
   __kmalloc_track_caller+0xa0/0x7dc
   kstrdup+0x54/0xac
   convert_context+0x48/0x2e4
   sidtab_context_to_sid+0x1c4/0x36c
   security_context_to_sid_core+0x168/0x238
   security_context_to_sid_default+0x14/0x24
   inode_doinit_use_xattr+0x164/0x1e4
   inode_doinit_with_dentry+0x1c0/0x488
   selinux_d_instantiate+0x20/0x34
   security_d_instantiate+0x70/0xbc
   d_splice_alias+0x4c/0x3c0
   ext4_lookup+0x1d8/0x200 [ext4]
   __lookup_slow+0x12c/0x1e4
   walk_component+0x100/0x200
   path_lookupat+0x88/0x118
   filename_lookup+0x98/0x130
   user_path_at_empty+0x48/0x60
   vfs_statx+0x84/0x140
   vfs_fstatat+0x20/0x30
   __se_sys_newfstatat+0x30/0x74
   __arm64_sys_newfstatat+0x1c/0x2c
   el0_svc_common.constprop.0+0x100/0x184
   do_el0_svc+0x1c/0x2c
   el0_svc+0x20/0x34
   el0_sync_handler+0x80/0x17c
   el0_sync+0x13c/0x140
  SELinux: Context system_u:object_r:pssp_rsyslog_log_t:s0:c0 is
           not valid (left unmapped).

It was found that within a critical section of spin_lock_irqsave in
sidtab_context_to_sid(), convert_context() (hooked by
sidtab_convert_params.func) might cause the process to sleep via
allocating memory with GFP_KERNEL, which is problematic.

As Ondrej pointed out [1], convert_context()/sidtab_convert_params.func
has another caller sidtab_convert_tree(), which is okay with GFP_KERNEL.
Therefore, fix this problem by adding a gfp_t argument for
convert_context()/sidtab_convert_params.func and pass GFP_KERNEL/_ATOMIC
properly in individual callers.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20221018120111.1474581-1-gongruiqi1@huawei.com/ [1]
Reported-by: Tan Ninghao <tanninghao1@huawei.com>
Fixes: ee1a84fdfe ("selinux: overhaul sidtab to fix bug and improve performance")
Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
[PM: wrap long BUG() output lines, tweak subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-10-19 09:55:53 -04:00
Xiu Jianfeng
73de1befcc selinux: fix memleak in security_read_state_kernel()
In this function, it directly returns the result of __security_read_policy
without freeing the allocated memory in *data, cause memory leak issue,
so free the memory if __security_read_policy failed.

Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-06-13 19:31:53 -04:00
Christian Göttsche
ded34574d4 selinux: declare data arrays const
The arrays for the policy capability names, the initial sid identifiers
and the class and permission names are not changed at runtime.  Declare
them const to avoid accidental modification.

Do not override the classmap and the initial sid list in the build time
script genheaders.

Check flose(3) is successful in genheaders.c, otherwise the written data
might be corrupted or incomplete.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: manual merge due to fuzz, minor style tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-05-03 15:53:49 -04:00
Christian Göttsche
a9029d9704 selinux: fix indentation level of mls_ops block
Add one level of indentation to the code block of the label mls_ops in
constraint_expr_eval(), to adjust the trailing break; to the parent
case: branch.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-05-03 14:26:53 -04:00
Michal Orzel
0a9876f36b selinux: Remove redundant assignments
Get rid of redundant assignments which end up in values not being
read either because they are overwritten or the function ends.

Reported by clang-tidy [deadcode.DeadStores]

Signed-off-by: Michal Orzel <michalorzel.eng@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-04-04 15:38:53 -04:00
Christian Göttsche
5ea33af9d4 selinux: drop return statement at end of void functions
Those return statements at the end of a void function are redundant.

Reported by clang-tidy [readability-redundant-control-flow]

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-02-18 10:42:12 -05:00
Christian Göttsche
0b3c2b3dc9 selinux: drop cast to same type
Both the lvalue scontextp and rvalue scontext are of the type char*.
Drop the redundant explicit cast not needed since commit 9a59daa03d
("SELinux: fix sleeping allocation in security_context_to_sid"), where
the type of scontext changed from const char* to char*.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-01-26 15:25:47 -05:00
Christian Göttsche
08df49054f selinux: declare path parameters of _genfs_sid const
The path parameter is only read from in security_genfs_sid(),
selinux_policy_genfs_sid() and __security_genfs_sid(). Since a string
literal is passed as argument, declare the parameter const.
Also align the parameter names in the declaration and definition.

Reported by clang [-Wwrite-strings]:

    security/selinux/hooks.c:553:60: error: passing 'const char [2]'
      to parameter of type 'char *' discards qualifiers
      [-Wincompatible-pointer-types-discards-qualifiers]
            rc = security_genfs_sid(&selinux_state, ... , /,
                                                          ^~~
    ./security/selinux/include/security.h:389:36: note: passing
      argument to parameter 'name' here
                           const char *fstype, char *name, u16 sclass,
                                                     ^

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: wrapped description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-01-25 19:59:52 -05:00
Paul Moore
e9fd729293 selinux: fix all of the W=1 build warnings
There were a number of places in the code where the function
definition did not match the associated comment block as well
at least one file where the appropriate header files were not
included (missing function declaration/prototype); this patch
fixes all of these issue such that building the SELinux code
with "W=1" is now warning free.

 % make W=1 security/selinux/

Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-10-13 16:31:51 -04:00
Ondrej Mosnacek
cbfcd13be5 selinux: fix race condition when computing ocontext SIDs
Current code contains a lot of racy patterns when converting an
ocontext's context structure to an SID. This is being done in a "lazy"
fashion, such that the SID is looked up in the SID table only when it's
first needed and then cached in the "sid" field of the ocontext
structure. However, this is done without any locking or memory barriers
and is thus unsafe.

Between commits 24ed7fdae6 ("selinux: use separate table for initial
SID lookup") and 66f8e2f03c ("selinux: sidtab reverse lookup hash
table"), this race condition lead to an actual observable bug, because a
pointer to the shared sid field was passed directly to
sidtab_context_to_sid(), which was using this location to also store an
intermediate value, which could have been read by other threads and
interpreted as an SID. In practice this caused e.g. new mounts to get a
wrong (seemingly random) filesystem context, leading to strange denials.
This bug has been spotted in the wild at least twice, see [1] and [2].

Fix the race condition by making all the racy functions use a common
helper that ensures the ocontext::sid accesses are made safely using the
appropriate SMP constructs.

Note that security_netif_sid() was populating the sid field of both
contexts stored in the ocontext, but only the first one was actually
used. The SELinux wiki's documentation on the "netifcon" policy
statement [3] suggests that using only the first context is intentional.
I kept only the handling of the first context here, as there is really
no point in doing the SID lookup for the unused one.

I wasn't able to reproduce the bug mentioned above on any kernel that
includes commit 66f8e2f03c, even though it has been reported that the
issue occurs with that commit, too, just less frequently. Thus, I wasn't
able to verify that this patch fixes the issue, but it makes sense to
avoid the race condition regardless.

[1] https://github.com/containers/container-selinux/issues/89
[2] https://lists.fedoraproject.org/archives/list/selinux@lists.fedoraproject.org/thread/6DMTAMHIOAOEMUAVTULJD45JZU7IBAFM/
[3] https://selinuxproject.org/page/NetworkStatements#netifcon

Cc: stable@vger.kernel.org
Cc: Xinjie Zheng <xinjie@google.com>
Reported-by: Sujithra Periasamy <sujithra@google.com>
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-10-11 19:18:04 -04:00
Austin Kim
893c47d196 selinux: return early for possible NULL audit buffers
audit_log_start() may return NULL in below cases:

  - when audit is not initialized.
  - when audit backlog limit exceeds.

After the call to audit_log_start() is made and then possible NULL audit
buffer argument is passed to audit_log_*() functions,
audit_log_*() functions return immediately in case of a NULL audit buffer
argument.

But it is optimal to return early when audit_log_start() returns NULL,
because it is not necessary for audit_log_*() functions to be called with
NULL audit buffer argument.

So add exception handling for possible NULL audit buffers where
return value can be handled from callers.

Signed-off-by: Austin Kim <austin.kim@lge.com>
[PM: tweak subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-07-14 15:25:27 -04:00
Yang Li
d0a83314db selinux: Fix kernel-doc
Fix function name and add comment for parameter state in ss/services.c 
kernel-doc to remove some warnings found by running make W=1 LLVM=1.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-06-11 12:59:45 -04:00
Jiapeng Chong
fd781f459b selinux: Remove redundant assignment to rc
Variable rc is set to '-EINVAL' but this value is never read as
it is overwritten or not used later on, hence it is a redundant
assignment and can be removed.

Cleans up the following clang-analyzer warning:

security/selinux/ss/services.c:2103:3: warning: Value stored to 'rc' is
never read [clang-analyzer-deadcode.DeadStores].

security/selinux/ss/services.c:2079:2: warning: Value stored to 'rc' is
never read [clang-analyzer-deadcode.DeadStores].

security/selinux/ss/services.c:2071:2: warning: Value stored to 'rc' is
never read [clang-analyzer-deadcode.DeadStores].

security/selinux/ss/services.c:2062:2: warning: Value stored to 'rc' is
never read [clang-analyzer-deadcode.DeadStores].

security/selinux/ss/policydb.c:2592:3: warning: Value stored to 'rc' is
never read [clang-analyzer-deadcode.DeadStores].

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-05-10 21:48:11 -04:00
Linus Torvalds
17ae69aba8 Add Landlock, a new LSM from Mickaël Salaün <mic@linux.microsoft.com>
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Merge tag 'landlock_v34' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull Landlock LSM from James Morris:
 "Add Landlock, a new LSM from Mickaël Salaün.

  Briefly, Landlock provides for unprivileged application sandboxing.

  From Mickaël's cover letter:
    "The goal of Landlock is to enable to restrict ambient rights (e.g.
     global filesystem access) for a set of processes. Because Landlock
     is a stackable LSM [1], it makes possible to create safe security
     sandboxes as new security layers in addition to the existing
     system-wide access-controls. This kind of sandbox is expected to
     help mitigate the security impact of bugs or unexpected/malicious
     behaviors in user-space applications. Landlock empowers any
     process, including unprivileged ones, to securely restrict
     themselves.

     Landlock is inspired by seccomp-bpf but instead of filtering
     syscalls and their raw arguments, a Landlock rule can restrict the
     use of kernel objects like file hierarchies, according to the
     kernel semantic. Landlock also takes inspiration from other OS
     sandbox mechanisms: XNU Sandbox, FreeBSD Capsicum or OpenBSD
     Pledge/Unveil.

     In this current form, Landlock misses some access-control features.
     This enables to minimize this patch series and ease review. This
     series still addresses multiple use cases, especially with the
     combined use of seccomp-bpf: applications with built-in sandboxing,
     init systems, security sandbox tools and security-oriented APIs [2]"

  The cover letter and v34 posting is here:

      https://lore.kernel.org/linux-security-module/20210422154123.13086-1-mic@digikod.net/

  See also:

      https://landlock.io/

  This code has had extensive design discussion and review over several
  years"

Link: https://lore.kernel.org/lkml/50db058a-7dde-441b-a7f9-f6837fe8b69f@schaufler-ca.com/ [1]
Link: https://lore.kernel.org/lkml/f646e1c7-33cf-333f-070c-0a40ad0468cd@digikod.net/ [2]

* tag 'landlock_v34' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  landlock: Enable user space to infer supported features
  landlock: Add user and kernel documentation
  samples/landlock: Add a sandbox manager example
  selftests/landlock: Add user space tests
  landlock: Add syscall implementations
  arch: Wire up Landlock syscalls
  fs,security: Add sb_delete hook
  landlock: Support filesystem access-control
  LSM: Infrastructure management of the superblock
  landlock: Add ptrace restrictions
  landlock: Set up the security framework and manage credentials
  landlock: Add ruleset and domain management
  landlock: Add object management
2021-05-01 18:50:44 -07:00
Linus Torvalds
f1c921fb70 selinux/stable-5.13 PR 20210426
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Merge tag 'selinux-pr-20210426' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:

 - Add support for measuring the SELinux state and policy capabilities
   using IMA.

 - A handful of SELinux/NFS patches to compare the SELinux state of one
   mount with a set of mount options. Olga goes into more detail in the
   patch descriptions, but this is important as it allows more
   flexibility when using NFS and SELinux context mounts.

 - Properly differentiate between the subjective and objective LSM
   credentials; including support for the SELinux and Smack. My clumsy
   attempt at a proper fix for AppArmor didn't quite pass muster so John
   is working on a proper AppArmor patch, in the meantime this set of
   patches shouldn't change the behavior of AppArmor in any way. This
   change explains the bulk of the diffstat beyond security/.

 - Fix a problem where we were not properly terminating the permission
   list for two SELinux object classes.

* tag 'selinux-pr-20210426' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: add proper NULL termination to the secclass_map permissions
  smack: differentiate between subjective and objective task credentials
  selinux: clarify task subjective and objective credentials
  lsm: separate security_task_getsecid() into subjective and objective variants
  nfs: account for selinux security context when deciding to share superblock
  nfs: remove unneeded null check in nfs_fill_super()
  lsm,selinux: add new hook to compare new mount to an existing mount
  selinux: fix misspellings using codespell tool
  selinux: fix misspellings using codespell tool
  selinux: measure state and policy capabilities
  selinux: Allow context mounts for unpriviliged overlayfs
2021-04-27 13:42:11 -07:00
Casey Schaufler
1aea780837 LSM: Infrastructure management of the superblock
Move management of the superblock->sb_security blob out of the
individual security modules and into the security infrastructure.
Instead of allocating the blobs from within the modules, the modules
tell the infrastructure how much space is required, and the space is
allocated there.

Cc: John Johansen <john.johansen@canonical.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210422154123.13086-6-mic@digikod.net
Signed-off-by: James Morris <jamorris@linux.microsoft.com>
2021-04-22 12:22:10 -07:00