linux-stable.git/security/apparmor, branch linux-6.9.y

ima: Avoid blocking in RCU read-side critical section

2024-06-27T11:52:30+00:00

commit 9a95c5bfbf02a0a7f5983280fe284a0ff0836c34 upstream.

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 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		|
==> 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: c7423dbdbc9e ("ima: Handle -ESTALE returned by ima_filter_rule_match()")
Cc: stable@vger.kernel.org
Signed-off-by: GUO Zihua 
Acked-by: John Johansen 
Reviewed-by: Mimi Zohar 
Reviewed-by: Casey Schaufler 
[PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case]
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman

lsm: use 32-bit compatible data types in LSM syscalls

2024-03-14T15:31:26+00:00

Change the size parameters in lsm_list_modules(), lsm_set_self_attr()
and lsm_get_self_attr() from size_t to u32. This avoids the need to
have different interfaces for 32 and 64 bit systems.

Cc: stable@vger.kernel.org
Fixes: a04a1198088a ("LSM: syscalls for current process attributes")
Fixes: ad4aff9ec25f ("LSM: Create lsm_list_modules system call")
Signed-off-by: Casey Schaufler 
Reported-and-reviewed-by: Dmitry V. Levin 
[PM: subject and metadata tweaks, syscall.h fixes]
Signed-off-by: Paul Moore

Merge tag 'lsm-pr-20240227' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

2024-02-28T01:00:10+00:00

Pull lsm fixes from Paul Moore:
 "Two small patches, one for AppArmor and one for SELinux, to fix
  potential uninitialized variable problems in the new LSM syscalls we
  added during the v6.8 merge window.

  We haven't been able to get a response from John on the AppArmor
  patch, but considering both the importance of the patch and it's
  rather simple nature it seems like a good idea to get this merged
  sooner rather than later.

  I'm sure John is just taking some much needed vacation; if we need to
  revise this when he gets back to his email we can"

* tag 'lsm-pr-20240227' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
  apparmor: fix lsm_get_self_attr()
  selinux: fix lsm_get_self_attr()

apparmor: fix lsm_get_self_attr()

2024-02-23T22:16:33+00:00

In apparmor_getselfattr() when an invalid AppArmor attribute is
requested, or a value hasn't been explicitly set for the requested
attribute, the label passed to aa_put_label() is not properly
initialized which can cause problems when the pointer value is non-NULL
and AppArmor attempts to drop a reference on the bogus label object.

Cc: Casey Schaufler 
Cc: John Johansen 
Fixes: 223981db9baf ("AppArmor: Add selfattr hooks")
Signed-off-by: Mickaël Salaün 
Reviewed-by: Paul Moore 
[PM: description changes as discussed with MS]
Signed-off-by: Paul Moore

exec: Check __FMODE_EXEC instead of in_execve for LSMs

2024-01-24T19:38:58+00:00

After commit 978ffcbf00d8 ("execve: open the executable file before
doing anything else"), current->in_execve was no longer in sync with the
open(). This broke AppArmor and TOMOYO which depend on this flag to
distinguish "open" operations from being "exec" operations.

Instead of moving around in_execve, switch to using __FMODE_EXEC, which
is where the "is this an exec?" intent is stored. Note that TOMOYO still
uses in_execve around cred handling.

Reported-by: Kevin Locke 
Closes: https://lore.kernel.org/all/ZbE4qn9_h14OqADK@kevinlocke.name
Suggested-by: Linus Torvalds 
Fixes: 978ffcbf00d8 ("execve: open the executable file before doing anything else")
Cc: Josh Triplett 
Cc: John Johansen 
Cc: Paul Moore 
Cc: James Morris 
Cc: Serge E. Hallyn 
Cc: Kentaro Takeda 
Cc: Tetsuo Handa 
Cc: Alexander Viro 
Cc: Christian Brauner 
Cc: Jan Kara 
Cc: Eric Biederman 
Cc: Andrew Morton 
Cc: Sebastian Andrzej Siewior 
Cc:  
Cc:  
Cc:  
Cc:  
Signed-off-by: Kees Cook 
Signed-off-by: Linus Torvalds

Merge tag 'apparmor-pr-2024-01-18' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor

2024-01-19T18:53:55+00:00

Pull AppArmor updates from John Johansen:
 "This adds a single feature, switch the hash used to check policy from
  sha1 to sha256

  There are fixes for two memory leaks, and refcount bug and a potential
  crash when a profile name is empty. Along with a couple minor code
  cleanups.

  Summary:

  Features
   - switch policy hash from sha1 to sha256

  Bug Fixes
   - Fix refcount leak in task_kill
   - Fix leak of pdb objects and trans_table
   - avoid crash when parse profie name is empty

  Cleanups
   - add static to stack_msg and nulldfa
   - more kernel-doc cleanups"

* tag 'apparmor-pr-2024-01-18' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor:
  apparmor: Fix memory leak in unpack_profile()
  apparmor: avoid crash when parsed profile name is empty
  apparmor: fix possible memory leak in unpack_trans_table
  apparmor: free the allocated pdb objects
  apparmor: Fix ref count leak in task_kill
  apparmor: cleanup network hook comments
  apparmor: add missing params to aa_may_ptrace kernel-doc comments
  apparmor: declare nulldfa as static
  apparmor: declare stack_msg as static
  apparmor: switch SECURITY_APPARMOR_HASH from sha1 to sha256

Merge tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2024-01-12T04:23:50+00:00

Pull misc filesystem updates from Al Viro:
 "Misc cleanups (the part that hadn't been picked by individual fs
  trees)"

* tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  apparmorfs: don't duplicate kfree_link()
  orangefs: saner arguments passing in readdir guts
  ocfs2_find_match(): there's no such thing as NULL or negative ->d_parent
  reiserfs_add_entry(): get rid of pointless namelen checks
  __ocfs2_add_entry(), ocfs2_prepare_dir_for_insert(): namelen checks
  ext4_add_entry(): ->d_name.len is never 0
  befs: d_obtain_alias(ERR_PTR(...)) will do the right thing
  affs: d_obtain_alias(ERR_PTR(...)) will do the right thing
  /proc/sys: use d_splice_alias() calling conventions to simplify failure exits
  hostfs: use d_splice_alias() calling conventions to simplify failure exits
  udf_fiiter_add_entry(): check for zero ->d_name.len is bogus...
  udf: d_obtain_alias(ERR_PTR(...)) will do the right thing...
  udf: d_splice_alias() will do the right thing on ERR_PTR() inode
  nfsd: kill stale comment about simple_fill_super() requirements
  bfs_add_entry(): get rid of pointless ->d_name.len checks
  nilfs2: d_obtain_alias(ERR_PTR(...)) will do the right thing...
  zonefs: d_splice_alias() will do the right thing on ERR_PTR() inode

Merge tag 'lsm-pr-20240105' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

2024-01-09T20:57:46+00:00

Pull security module updates from Paul Moore:

 - Add three new syscalls: lsm_list_modules(), lsm_get_self_attr(), and
   lsm_set_self_attr().

   The first syscall simply lists the LSMs enabled, while the second and
   third get and set the current process' LSM attributes. Yes, these
   syscalls may provide similar functionality to what can be found under
   /proc or /sys, but they were designed to support multiple,
   simultaneaous (stacked) LSMs from the start as opposed to the current
   /proc based solutions which were created at a time when only one LSM
   was allowed to be active at a given time.

   We have spent considerable time discussing ways to extend the
   existing /proc interfaces to support multiple, simultaneaous LSMs and
   even our best ideas have been far too ugly to support as a kernel
   API; after +20 years in the kernel, I felt the LSM layer had
   established itself enough to justify a handful of syscalls.

   Support amongst the individual LSM developers has been nearly
   unanimous, with a single objection coming from Tetsuo (TOMOYO) as he
   is worried that the LSM_ID_XXX token concept will make it more
   difficult for out-of-tree LSMs to survive. Several members of the LSM
   community have demonstrated the ability for out-of-tree LSMs to
   continue to exist by picking high/unused LSM_ID values as well as
   pointing out that many kernel APIs rely on integer identifiers, e.g.
   syscalls (!), but unfortunately Tetsuo's objections remain.

   My personal opinion is that while I have no interest in penalizing
   out-of-tree LSMs, I'm not going to penalize in-tree development to
   support out-of-tree development, and I view this as a necessary step
   forward to support the push for expanded LSM stacking and reduce our
   reliance on /proc and /sys which has occassionally been problematic
   for some container users. Finally, we have included the linux-api
   folks on (all?) recent revisions of the patchset and addressed all of
   their concerns.

 - Add a new security_file_ioctl_compat() LSM hook to handle the 32-bit
   ioctls on 64-bit systems problem.

   This patch includes support for all of the existing LSMs which
   provide ioctl hooks, although it turns out only SELinux actually
   cares about the individual ioctls. It is worth noting that while
   Casey (Smack) and Tetsuo (TOMOYO) did not give explicit ACKs to this
   patch, they did both indicate they are okay with the changes.

 - Fix a potential memory leak in the CALIPSO code when IPv6 is disabled
   at boot.

   While it's good that we are fixing this, I doubt this is something
   users are seeing in the wild as you need to both disable IPv6 and
   then attempt to configure IPv6 labeled networking via
   NetLabel/CALIPSO; that just doesn't make much sense.

   Normally this would go through netdev, but Jakub asked me to take
   this patch and of all the trees I maintain, the LSM tree seemed like
   the best fit.

 - Update the LSM MAINTAINERS entry with additional information about
   our process docs, patchwork, bug reporting, etc.

   I also noticed that the Lockdown LSM is missing a dedicated
   MAINTAINERS entry so I've added that to the pull request. I've been
   working with one of the major Lockdown authors/contributors to see if
   they are willing to step up and assume a Lockdown maintainer role;
   hopefully that will happen soon, but in the meantime I'll continue to
   look after it.

 - Add a handful of mailmap entries for Serge Hallyn and myself.

* tag 'lsm-pr-20240105' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm: (27 commits)
  lsm: new security_file_ioctl_compat() hook
  lsm: Add a __counted_by() annotation to lsm_ctx.ctx
  calipso: fix memory leak in netlbl_calipso_add_pass()
  selftests: remove the LSM_ID_IMA check in lsm/lsm_list_modules_test
  MAINTAINERS: add an entry for the lockdown LSM
  MAINTAINERS: update the LSM entry
  mailmap: add entries for Serge Hallyn's dead accounts
  mailmap: update/replace my old email addresses
  lsm: mark the lsm_id variables are marked as static
  lsm: convert security_setselfattr() to use memdup_user()
  lsm: align based on pointer length in lsm_fill_user_ctx()
  lsm: consolidate buffer size handling into lsm_fill_user_ctx()
  lsm: correct error codes in security_getselfattr()
  lsm: cleanup the size counters in security_getselfattr()
  lsm: don't yet account for IMA in LSM_CONFIG_COUNT calculation
  lsm: drop LSM_ID_IMA
  LSM: selftests for Linux Security Module syscalls
  SELinux: Add selfattr hooks
  AppArmor: Add selfattr hooks
  Smack: implement setselfattr and getselfattr hooks
  ...

apparmor: Fix memory leak in unpack_profile()

2024-01-09T09:45:25+00:00

The aa_put_pdb(rules->file) should be called when rules->file is
reassigned, otherwise there may be a memory leak.

This was found via kmemleak:

unreferenced object 0xffff986c17056600 (size 192):
  comm "apparmor_parser", pid 875, jiffies 4294893488
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 89 14 04 6c 98 ff ff  ............l...
    00 00 8c 11 6c 98 ff ff bc 0c 00 00 00 00 00 00  ....l...........
  backtrace (crc e28c80c4):
    [] kmemleak_alloc+0x4f/0x90
    [] kmalloc_trace+0x2d2/0x340
    [] aa_alloc_pdb+0x4d/0x90
    [] unpack_pdb+0x48/0x660
    [] unpack_profile+0x693/0x1090
    [] aa_unpack+0x10a/0x6e0
    [] aa_replace_profiles+0xa3/0x1210
    [] policy_update+0x163/0x2a0
    [] profile_replace+0xb1/0x130
    [] vfs_write+0xd4/0x3d0
    [] ksys_write+0x6b/0xf0
    [] __x64_sys_write+0x1e/0x30
    [] do_syscall_64+0x76/0x120
    [] entry_SYSCALL_64_after_hwframe+0x6c/0x74

So add aa_put_pdb(rules->file) to fix it when rules->file is reassigned.

Fixes: 98b824ff8984 ("apparmor: refcount the pdb")
Signed-off-by: Gaosheng Cui 
Signed-off-by: John Johansen

apparmor: avoid crash when parsed profile name is empty

2024-01-04T09:35:39+00:00

When processing a packed profile in unpack_profile() described like

 "profile :ns::samba-dcerpcd /usr/lib*/samba/{,samba/}samba-dcerpcd {...}"

a string ":samba-dcerpcd" is unpacked as a fully-qualified name and then
passed to aa_splitn_fqname().

aa_splitn_fqname() treats ":samba-dcerpcd" as only containing a namespace.
Thus it returns NULL for tmpname, meanwhile tmpns is non-NULL. Later
aa_alloc_profile() crashes as the new profile name is NULL now.

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 6 PID: 1657 Comm: apparmor_parser Not tainted 6.7.0-rc2-dirty #16
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014
RIP: 0010:strlen+0x1e/0xa0
Call Trace:
 
 ? strlen+0x1e/0xa0
 aa_policy_init+0x1bb/0x230
 aa_alloc_profile+0xb1/0x480
 unpack_profile+0x3bc/0x4960
 aa_unpack+0x309/0x15e0
 aa_replace_profiles+0x213/0x33c0
 policy_update+0x261/0x370
 profile_replace+0x20e/0x2a0
 vfs_write+0x2af/0xe00
 ksys_write+0x126/0x250
 do_syscall_64+0x46/0xf0
 entry_SYSCALL_64_after_hwframe+0x6e/0x76
 
---[ end trace 0000000000000000 ]---
RIP: 0010:strlen+0x1e/0xa0

It seems such behaviour of aa_splitn_fqname() is expected and checked in
other places where it is called (e.g. aa_remove_profiles). Well, there
is an explicit comment "a ns name without a following profile is allowed"
inside.

AFAICS, nothing can prevent unpacked "name" to be in form like
":samba-dcerpcd" - it is passed from userspace.

Deny the whole profile set replacement in such case and inform user with
EPROTO and an explaining message.

Found by Linux Verification Center (linuxtesting.org).

Fixes: 04dc715e24d0 ("apparmor: audit policy ns specified in policy load")
Signed-off-by: Fedor Pchelkin 
Signed-off-by: John Johansen