kernel/git/stable/linux.git/security/apparmor/domain.c, branch master

apparmor: fix deadlock in complain-mode change_hat

2026-08-16T06:39:38+00:00

The use of change_hat when in complain mode can cause a deadlock when the hat doesn't exist and a new learning profile is created for the missing profile. This is because change_hat() has taken the lock to search the hat list and creating the new learning profile needs to take the lock to add it to the list. From the bug report: Originally found in 7.0.0 in LTS ubuntu 26.04 with pam_apparmor + su in complain mode set to change hats. Then verified in newest available vanilla kernel I've compiled to see if still present: 7.2-rc7 vanilla -> affected checked also some other kernels: 6.18.44 vanilla -> affected 6.12.95 with debian patches -> unaffected On systems without bug (for example 6.12.95 debian) it just prints: aa_change_hat rc=0 On systems with bug, the executable always hangs, prints nothing and becomes unkillable. (And once stuck this way, it will cause any further hat changes to also cause the changing process to get stuck) Then in syslog you can find hint about cause: kernel: INFO: task hat:3409 blocked for more than 483 seconds. kernel: Not tainted 7.2.0-rc7 #1 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kernel: task:hat state:D stack:0 pid:3409 tgid:3409 ppid:2605 task_flags:0x400000 flags:0x00080800 kernel: Call Trace: kernel: kernel: __schedule+0x48f/0xfe0 kernel: schedule+0x27/0xa0 kernel: schedule_preempt_disabled+0x15/0x30 kernel: __mutex_lock.constprop.0+0x569/0xa10 kernel: aa_new_learning_profile+0x15f/0x210 kernel: build_change_hat+0x19f/0x3b0 kernel: change_hat.isra.0+0x5dd/0xd60 kernel: aa_change_hat+0x2f3/0x710 kernel: aa_setprocattr_changehat+0x121/0x1f0 kernel: do_setattr+0x28c/0x340 kernel: apparmor_setselfattr+0x20/0x50 kernel: security_setselfattr+0xf6/0x110 kernel: __x64_sys_lsm_set_self_attr+0x53/0x90 kernel: do_syscall_64+0xdd/0x5e0 kernel: ? __mod_memcg_lruvec_state+0xfd/0x260 kernel: ? lruvec_stat_mod_folio+0x8d/0xd0 kernel: ? __folio_mod_stat+0x2d/0x90 kernel: ? map_anon_folio_pte_nopf+0xd1/0x1f0 kernel: ? do_anonymous_page+0x184/0xa10 kernel: ? __handle_mm_fault+0x805/0x870 kernel: ? count_memcg_events+0xef/0x230 kernel: ? handle_mm_fault+0x1f0/0x2f0 kernel: ? do_user_addr_fault+0x2bb/0x7b0 kernel: ? do_syscall_64+0x94/0x5e0 kernel: ? exc_page_fault+0x75/0x160 kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e kernel: RIP: 0033:0x7f815e134c8d kernel: RSP: 002b:00007fff6df94ea8 EFLAGS: 00000246 ORIG_RAX: 00000000000001cc kernel: RAX: ffffffffffffffda RBX: 0000556d8c81d040 RCX: 00007f815e134c8d kernel: RDX: 0000000000000046 RSI: 0000556d8c81d040 RDI: 0000000000000064 kernel: RBP: 00007fff6df94ef0 R08: 00007f815e212ac8 R09: 000000000000000c kernel: R10: 0000000000000000 R11: 0000000000000246 R12: 0000556d8c81d010 kernel: R13: 0000000000000026 R14: 0000000000000046 R15: 0000000000000064 kernel: kernel: INFO: task hat:3409 is blocked on a mutex likely owned by task hat:3409. To fix the issue, lift the locking out of the core of aa_new_learning_profile(), introduce a wrapper function that takes the lock where needed, and have build_change_hat() call the core function that no longer takes the lock. In addition fix 4 other issues introduced by commit 32e92764d6f8d ("apparmor: grab ns lock and refresh when looking up changehat child profiles") - aa_get_profile_rcu() was replaced-by: aa_get_profile without the accompanying rcu_dereference_protected() - an extra aa_get_label(label) was introduced at the start of change_hat() without an accompanying aa_put_label() causing a reference count leak. - a reference count leak was introduced in the label_is_stale(label) case, where the newest profile would be leaked instead of the label passed to the function. - a potential UAF when the lookup walks up the tree with new_ns != ns the new label reference is put, and then used for the next lookup. The mutex_lock, will block replacement, and removal in the locked ns. However there are two cases where putting the reference can result in the label being freed even with the lock held. 1. the label does not have a list reference (possible for temporary or special profiles) in which case the put can trigger the cleanup. 2. the new label reference is in a different namespace, which does not have a lock held on it. This extends case 1 to also include replacement, and removal that could be occurring in the namespace new is in. Reported-by: Martin Petricek Link: https://lists.ubuntu.com/archives/apparmor/2026-August/014907.html Fixes: 32e92764d6f8d ("apparmor: grab ns lock and refresh when looking up changehat child profiles") Signed-off-by: John Johansen

apparmor: constify aa_profile parameters on read-only compute paths

2026-08-11T05:49:43+00:00

A number of functions take a struct aa_profile * argument that is only ever read from: they compute DFA matches or apply the profile's mode flags without modifying the profile, taking a reference on it, or touching its embedded label. Mark those parameters const struct aa_profile * to document intent and let the compiler enforce it. The converted functions are the permission "compute" path plus a few pure readers: - aa_apply_modes_to_perms(), aa_profile_match_label() - AUDIT_MODE() - aa_label_match() and its match_component()/label_compound_match()/ label_components_match() helpers (label.c) - match_component()/label_compound_match()/label_components_match()/ label_match()/change_profile_perms()/aa_xattrs_match() (domain.c) - match_iface()/match_addr_iface()/match_addr_iface_label()/ skb_match_to_sk()/skb_match_to_cmd() (af_inet.c) - aa_profile_capget(), path_flags(), profile_query_cb() The remaining aa_profile * parameters cannot be made const: the audit path stores &profile->label into the owned, refcounted apparmor_audit_data.subj_label/peer fields, and the domain/lifecycle paths take references on the profile's embedded label (aa_get_label()/aa_get_newest_label()/aa_get_profile()) or write profile fields. No functional change. Signed-off-by: John Johansen Assisted-by: Claude:claude-opus-4.8

apparmor: refactor xattr attachment, to take the file path

2026-08-11T05:49:42+00:00

The full bprm does not need to be passed into xattrs_match, so only pass in the path, and propagate the change backup the call stack until bprm is actually needed. Reviewed-by: Georgia Garcia Signed-off-by: John Johansen

apparmor: fix unconfined user namespace restriction forced stack

2026-08-11T05:49:42+00:00

If a task is already confined by a stack the unprivileged transition restriction on unconfined is not correctly, applied. This results in an escape if two transitions through an unconfined profile can be executed. Fix this by pushing the check into the per profile label build. The check will always be done against unconfined and result in a stack of just the unconfined component when necessary. Fixes: 2d9da9b188b8 ("apparmor: allow restricting unprivileged change_profile") Signed-off-by: John Johansen

apparmor: make include headers self-contained

2026-06-29T17:26:36+00:00

Besides of resolving clangd IDE warnings, self-contained headers will be less likely to break if the surrounding includes in .c files using them change. Signed-off-by: Ryan Lee Signed-off-by: John Johansen

security: apparmor: fix two spelling mistakes

2026-06-14T03:20:13+00:00

Fix two spelling errors in comment: - interated → interacted - dont → don't Signed-off-by: Qingshuang Fu Signed-off-by: John Johansen

apparmor: change fn_label_build() call to not return NULL

2026-06-14T03:14:07+00:00

Previously fn_label_build() was accepting a NULL which represented ENOMEM return and ERR_PTR for errors. Clean this up by requiring the cb fn to return an ERR_PTR or valid value. Reviewed-by: Georgia Garcia Signed-off-by: John Johansen

apparmor: grab ns lock and refresh when looking up changehat child profiles

2026-06-14T03:14:07+00:00

There was a race condition involving change_hat and profile replacement in which replacement of the parent profile during a changehat operation could result in the list of children becoming empty and the changehat operation failing. To prevent this: - grab the namespace lock until we've built the hat transition, and - use aa_get_newest_profile to avoid using stale profile objects. Link: https://bugs.launchpad.net/bugs/2139664 Fixes: 89dbf1962aa63 ("apparmor: move change_hat mediation to using labels") Reviewed-by: Georgia Garcia Signed-off-by: Ryan Lee Signed-off-by: John Johansen

apparmor: check label build before no_new_privs test

2026-06-14T03:14:06+00:00

aa_change_profile() builds a replacement label with fn_label_build_in_scope() before the no_new_privs subset check. The build helper can fail and return NULL or an ERR_PTR, but the result was passed to aa_label_is_unconfined_subset() before the existing IS_ERR_OR_NULL() check. Reuse the existing target-label build failure handling immediately after the build. This preserves the current audit handling while preventing the subset helper from dereferencing an invalid label. Fixes: e00b02bb6ac2a ("apparmor: move change_profile mediation to using labels") Signed-off-by: Ruoyu Wang Signed-off-by: John Johansen

apparmor: split xxx_in_ns into its two separate semantic use cases

2026-01-29T09:27:55+00:00

This patch doesn't change current functionality, it switches the two uses of the in_ns fns and macros into the two semantically different cases they are used for. xxx_in_scope for checking mediation interaction between profiles xxx_in_view to determine which profiles are visible.The scope will always be a subset of the view as profiles that can not see each other can not interact. The split can not be completely done for label_match because it has to distinct uses matching permission against label in scope, and checking if a transition to a profile is allowed. The transition to a profile can include profiles that are in view but not in scope, so retain this distinction as a parameter. While at the moment the two uses are very similar, in the future there will be additional differences. So make sure the semantics differences are present in the code. Reviewed-by: Georgia Garcia Signed-off-by: John Johansen