<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/security/apparmor/include, branch v6.13-rc6</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>parser: drop dead code for XXX_comb macros</title>
<updated>2024-11-27T03:21:06+00:00</updated>
<author>
<name>John Johansen</name>
<email>john.johansen@canonical.com</email>
</author>
<published>2024-11-09T20:47:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=9133493a76d741e1ce00a140be3d2d7791ca3a04'/>
<id>9133493a76d741e1ce00a140be3d2d7791ca3a04</id>
<content type='text'>
The macros for label combination XXX_comb are no longer used and there
are no plans to use them so remove the dead code.

Signed-off-by: John Johansen &lt;john.johansen@canonical.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The macros for label combination XXX_comb are no longer used and there
are no plans to use them so remove the dead code.

Signed-off-by: John Johansen &lt;john.johansen@canonical.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>apparmor: Remove unused parameter L1 in macro next_comb</title>
<updated>2024-11-27T03:21:06+00:00</updated>
<author>
<name>Jinjie Ruan</name>
<email>ruanjinjie@huawei.com</email>
</author>
<published>2024-09-02T07:39:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=211551768291a9accdd0d033c6d9ff51dc4e9840'/>
<id>211551768291a9accdd0d033c6d9ff51dc4e9840</id>
<content type='text'>
In the macro definition of next_comb(), a parameter L1 is accepted,
but it is not used. Hence, it should be removed.

Signed-off-by: Jinjie Ruan &lt;ruanjinjie@huawei.com&gt;
Signed-off-by: John Johansen &lt;john.johansen@canonical.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In the macro definition of next_comb(), a parameter L1 is accepted,
but it is not used. Hence, it should be removed.

Signed-off-by: Jinjie Ruan &lt;ruanjinjie@huawei.com&gt;
Signed-off-by: John Johansen &lt;john.johansen@canonical.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>apparmor: Remove deadcode</title>
<updated>2024-11-27T03:21:05+00:00</updated>
<author>
<name>Dr. David Alan Gilbert</name>
<email>linux@treblig.org</email>
</author>
<published>2024-09-20T23:55:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=75535669c9c1647e8098947f045c95db1bbdfa8c'/>
<id>75535669c9c1647e8098947f045c95db1bbdfa8c</id>
<content type='text'>
aa_label_audit, aa_label_find, aa_label_seq_print and aa_update_label_name
were added by commit
f1bd904175e8 ("apparmor: add the base fns() for domain labels")
but never used.

aa_profile_label_perm was added by commit
637f688dc3dc ("apparmor: switch from profiles to using labels on contexts")
but never used.

aa_secid_update was added by commit
c092921219d2 ("apparmor: add support for mapping secids and using secctxes")
but never used.

aa_split_fqname has been unused since commit
3664268f19ea ("apparmor: add namespace lookup fns()")

aa_lookup_profile has been unused since commit
93c98a484c49 ("apparmor: move exec domain mediation to using labels")

aa_audit_perms_cb was only used by aa_profile_label_perm (see above).

All of these commits are from around 2017.

Remove them.

Signed-off-by: Dr. David Alan Gilbert &lt;linux@treblig.org&gt;
Signed-off-by: John Johansen &lt;john.johansen@canonical.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
aa_label_audit, aa_label_find, aa_label_seq_print and aa_update_label_name
were added by commit
f1bd904175e8 ("apparmor: add the base fns() for domain labels")
but never used.

aa_profile_label_perm was added by commit
637f688dc3dc ("apparmor: switch from profiles to using labels on contexts")
but never used.

aa_secid_update was added by commit
c092921219d2 ("apparmor: add support for mapping secids and using secctxes")
but never used.

aa_split_fqname has been unused since commit
3664268f19ea ("apparmor: add namespace lookup fns()")

aa_lookup_profile has been unused since commit
93c98a484c49 ("apparmor: move exec domain mediation to using labels")

aa_audit_perms_cb was only used by aa_profile_label_perm (see above).

All of these commits are from around 2017.

Remove them.

Signed-off-by: Dr. David Alan Gilbert &lt;linux@treblig.org&gt;
Signed-off-by: John Johansen &lt;john.johansen@canonical.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>apparmor: add support for 2^24 states to the dfa state machine.</title>
<updated>2024-11-27T03:21:05+00:00</updated>
<author>
<name>John Johansen</name>
<email>john.johansen@canonical.com</email>
</author>
<published>2024-08-24T04:40:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=9208c05f9fdfd927ea160b97dfef3c379049fff2'/>
<id>9208c05f9fdfd927ea160b97dfef3c379049fff2</id>
<content type='text'>
Currently the dfa state machine is limited by its default, next, and
check tables using u16. Allow loading of u32 tables, and if u16 tables
are loaded map them to u32.

The number of states allowed does not increase to 2^32 because the
base table uses the top 8 bits of its u32 for flags. Moving the flags
into a separate table allowing a full 2^32 bit range wil be done in
a separate patch.

Link: https://gitlab.com/apparmor/apparmor/-/issues/419
Signed-off-by: John Johansen &lt;john.johansen@canonical.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Currently the dfa state machine is limited by its default, next, and
check tables using u16. Allow loading of u32 tables, and if u16 tables
are loaded map them to u32.

The number of states allowed does not increase to 2^32 because the
base table uses the top 8 bits of its u32 for flags. Moving the flags
into a separate table allowing a full 2^32 bit range wil be done in
a separate patch.

Link: https://gitlab.com/apparmor/apparmor/-/issues/419
Signed-off-by: John Johansen &lt;john.johansen@canonical.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>lsm: add lsmprop_to_secctx hook</title>
<updated>2024-10-11T18:34:12+00:00</updated>
<author>
<name>Casey Schaufler</name>
<email>casey@schaufler-ca.com</email>
</author>
<published>2024-10-09T17:32:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=6f2f724f0e116d9ea960ff3dd645add12e60e176'/>
<id>6f2f724f0e116d9ea960ff3dd645add12e60e176</id>
<content type='text'>
Add a new hook security_lsmprop_to_secctx() and its LSM specific
implementations. The LSM specific code will use the lsm_prop element
allocated for that module. This allows for the possibility that more
than one module may be called upon to translate a secid to a string,
as can occur in the audit code.

Signed-off-by: Casey Schaufler &lt;casey@schaufler-ca.com&gt;
[PM: subject line tweak]
Signed-off-by: Paul Moore &lt;paul@paul-moore.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add a new hook security_lsmprop_to_secctx() and its LSM specific
implementations. The LSM specific code will use the lsm_prop element
allocated for that module. This allows for the possibility that more
than one module may be called upon to translate a secid to a string,
as can occur in the audit code.

Signed-off-by: Casey Schaufler &lt;casey@schaufler-ca.com&gt;
[PM: subject line tweak]
Signed-off-by: Paul Moore &lt;paul@paul-moore.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>lsm: use lsm_prop in security_audit_rule_match</title>
<updated>2024-10-11T18:34:12+00:00</updated>
<author>
<name>Casey Schaufler</name>
<email>casey@schaufler-ca.com</email>
</author>
<published>2024-10-09T17:32:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=870b7fdc660b38c4e1bd8bf48e62aa352ddf8f42'/>
<id>870b7fdc660b38c4e1bd8bf48e62aa352ddf8f42</id>
<content type='text'>
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 &lt;casey@schaufler-ca.com&gt;
[PM: subject line tweak]
Signed-off-by: Paul Moore &lt;paul@paul-moore.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &lt;casey@schaufler-ca.com&gt;
[PM: subject line tweak]
Signed-off-by: Paul Moore &lt;paul@paul-moore.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>lsm: infrastructure management of the sock security</title>
<updated>2024-07-29T20:54:50+00:00</updated>
<author>
<name>Casey Schaufler</name>
<email>casey@schaufler-ca.com</email>
</author>
<published>2024-07-10T21:32:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=2aff9d20d50ac45dd13a013ef5231f4fb8912356'/>
<id>2aff9d20d50ac45dd13a013ef5231f4fb8912356</id>
<content type='text'>
Move management of the sock-&gt;sk_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.

Acked-by: Paul Moore &lt;paul@paul-moore.com&gt;
Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Reviewed-by: John Johansen &lt;john.johansen@canonical.com&gt;
Acked-by: Stephen Smalley &lt;stephen.smalley.work@gmail.com&gt;
Signed-off-by: Casey Schaufler &lt;casey@schaufler-ca.com&gt;
[PM: subject tweak]
Signed-off-by: Paul Moore &lt;paul@paul-moore.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Move management of the sock-&gt;sk_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.

Acked-by: Paul Moore &lt;paul@paul-moore.com&gt;
Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Reviewed-by: John Johansen &lt;john.johansen@canonical.com&gt;
Acked-by: Stephen Smalley &lt;stephen.smalley.work@gmail.com&gt;
Signed-off-by: Casey Schaufler &lt;casey@schaufler-ca.com&gt;
[PM: subject tweak]
Signed-off-by: Paul Moore &lt;paul@paul-moore.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'apparmor-pr-2024-07-25' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor</title>
<updated>2024-07-27T20:28:39+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-07-27T20:28:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=ff30564411ffdcee49d579cb15eb13185a36e253'/>
<id>ff30564411ffdcee49d579cb15eb13185a36e253</id>
<content type='text'>
Pull apparmor updates from John Johansen:
 "Cleanups
   - optimization: try to avoid refing the label in apparmor_file_open
   - remove useless static inline function is_deleted
   - use kvfree_sensitive to free data-&gt;data
   - fix typo in kernel doc

  Bug fixes:
   - unpack transition table if dfa is not present
   - test: add MODULE_DESCRIPTION()
   - take nosymfollow flag into account
   - fix possible NULL pointer dereference
   - fix null pointer deref when receiving skb during sock creation"

* tag 'apparmor-pr-2024-07-25' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor:
  apparmor: unpack transition table if dfa is not present
  apparmor: try to avoid refing the label in apparmor_file_open
  apparmor: test: add MODULE_DESCRIPTION()
  apparmor: take nosymfollow flag into account
  apparmor: fix possible NULL pointer dereference
  apparmor: fix typo in kernel doc
  apparmor: remove useless static inline function is_deleted
  apparmor: use kvfree_sensitive to free data-&gt;data
  apparmor: Fix null pointer deref when receiving skb during sock creation
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull apparmor updates from John Johansen:
 "Cleanups
   - optimization: try to avoid refing the label in apparmor_file_open
   - remove useless static inline function is_deleted
   - use kvfree_sensitive to free data-&gt;data
   - fix typo in kernel doc

  Bug fixes:
   - unpack transition table if dfa is not present
   - test: add MODULE_DESCRIPTION()
   - take nosymfollow flag into account
   - fix possible NULL pointer dereference
   - fix null pointer deref when receiving skb during sock creation"

* tag 'apparmor-pr-2024-07-25' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor:
  apparmor: unpack transition table if dfa is not present
  apparmor: try to avoid refing the label in apparmor_file_open
  apparmor: test: add MODULE_DESCRIPTION()
  apparmor: take nosymfollow flag into account
  apparmor: fix possible NULL pointer dereference
  apparmor: fix typo in kernel doc
  apparmor: remove useless static inline function is_deleted
  apparmor: use kvfree_sensitive to free data-&gt;data
  apparmor: Fix null pointer deref when receiving skb during sock creation
</pre>
</div>
</content>
</entry>
<entry>
<title>apparmor: try to avoid refing the label in apparmor_file_open</title>
<updated>2024-07-24T18:05:14+00:00</updated>
<author>
<name>Mateusz Guzik</name>
<email>mjguzik@gmail.com</email>
</author>
<published>2024-06-20T17:15:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=f4fee216df7d28b87d1c9cc60bcebfecb51c1a05'/>
<id>f4fee216df7d28b87d1c9cc60bcebfecb51c1a05</id>
<content type='text'>
If the label is not stale (which is the common case), the fact that the
passed file object holds a reference can be leverged to avoid the
ref/unref cycle. Doing so reduces performance impact of apparmor on
parallel open() invocations.

When benchmarking on a 24-core vm using will-it-scale's open1_process
("Separate file open"), the results are (ops/s):
before: 6092196
after:  8309726 (+36%)

Signed-off-by: Mateusz Guzik &lt;mjguzik@gmail.com&gt;
Signed-off-by: John Johansen &lt;john.johansen@canonical.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
If the label is not stale (which is the common case), the fact that the
passed file object holds a reference can be leverged to avoid the
ref/unref cycle. Doing so reduces performance impact of apparmor on
parallel open() invocations.

When benchmarking on a 24-core vm using will-it-scale's open1_process
("Separate file open"), the results are (ops/s):
before: 6092196
after:  8309726 (+36%)

Signed-off-by: Mateusz Guzik &lt;mjguzik@gmail.com&gt;
Signed-off-by: John Johansen &lt;john.johansen@canonical.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ima: Avoid blocking in RCU read-side critical section</title>
<updated>2024-06-13T18:26:50+00:00</updated>
<author>
<name>GUO Zihua</name>
<email>guozihua@huawei.com</email>
</author>
<published>2024-05-07T01:25:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=9a95c5bfbf02a0a7f5983280fe284a0ff0836c34'/>
<id>9a95c5bfbf02a0a7f5983280fe284a0ff0836c34</id>
<content type='text'>
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 &lt;44&gt; 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 c7423dbdbc9e ("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		|
==&gt; synchronize_rcu returns early
|  kfree(entry)		|			|
|			|    entry = entry-&gt;next|
==&gt; UAF happens and entry now becomes NULL (or could be anything).
|			|    entry-&gt;action	|
==&gt; 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: c7423dbdbc9e ("ima: Handle -ESTALE returned by ima_filter_rule_match()")
Cc: stable@vger.kernel.org
Signed-off-by: GUO Zihua &lt;guozihua@huawei.com&gt;
Acked-by: John Johansen &lt;john.johansen@canonical.com&gt;
Reviewed-by: Mimi Zohar &lt;zohar@linux.ibm.com&gt;
Reviewed-by: Casey Schaufler &lt;casey@schaufler-ca.com&gt;
[PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case]
Signed-off-by: Paul Moore &lt;paul@paul-moore.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &lt;44&gt; 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 c7423dbdbc9e ("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		|
==&gt; synchronize_rcu returns early
|  kfree(entry)		|			|
|			|    entry = entry-&gt;next|
==&gt; UAF happens and entry now becomes NULL (or could be anything).
|			|    entry-&gt;action	|
==&gt; 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: c7423dbdbc9e ("ima: Handle -ESTALE returned by ima_filter_rule_match()")
Cc: stable@vger.kernel.org
Signed-off-by: GUO Zihua &lt;guozihua@huawei.com&gt;
Acked-by: John Johansen &lt;john.johansen@canonical.com&gt;
Reviewed-by: Mimi Zohar &lt;zohar@linux.ibm.com&gt;
Reviewed-by: Casey Schaufler &lt;casey@schaufler-ca.com&gt;
[PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case]
Signed-off-by: Paul Moore &lt;paul@paul-moore.com&gt;
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