summaryrefslogtreecommitdiff
path: root/kernel
diff options
context:
space:
mode:
authorPaul Moore <paul@paul-moore.com>2023-10-09 13:18:49 -0400
committerPaul Moore <paul@paul-moore.com>2023-10-25 22:29:47 -0400
commit47846d51348dd62e5231a83be040981b17c955fa (patch)
treee55ec806ed34593bf383a9e2f3348eeff2db03dc /kernel
parent97f576eb38ae219a6fb337d13586d8acbf01d3f8 (diff)
audit: don't take task_lock() in audit_exe_compare() code path
The get_task_exe_file() function locks the given task with task_lock() which when used inside audit_exe_compare() can cause deadlocks on systems that generate audit records when the task_lock() is held. We resolve this problem with two changes: ignoring those cases where the task being audited is not the current task, and changing our approach to obtaining the executable file struct to not require task_lock(). With the intent of the audit exe filter being to filter on audit events generated by processes started by the specified executable, it makes sense that we would only want to use the exe filter on audit records associated with the currently executing process, e.g. @current. If we are asked to filter records using a non-@current task_struct we can safely ignore the exe filter without negatively impacting the admin's expectations for the exe filter. Knowing that we only have to worry about filtering the currently executing task in audit_exe_compare() we can do away with the task_lock() and call get_mm_exe_file() with @current->mm directly. Cc: <stable@vger.kernel.org> Fixes: 5efc244346f9 ("audit: fix exe_file access in audit_exe_compare") Reported-by: Andreas Steinmetz <anstein99@googlemail.com> Reviewed-by: John Johansen <john.johanse@canonical.com> Reviewed-by: Mateusz Guzik <mjguzik@gmail.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/audit_watch.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
index 65075f1e4ac8..91e82e34b51e 100644
--- a/kernel/audit_watch.c
+++ b/kernel/audit_watch.c
@@ -527,11 +527,18 @@ int audit_exe_compare(struct task_struct *tsk, struct audit_fsnotify_mark *mark)
unsigned long ino;
dev_t dev;
- exe_file = get_task_exe_file(tsk);
+ /* only do exe filtering if we are recording @current events/records */
+ if (tsk != current)
+ return 0;
+
+ if (WARN_ON_ONCE(!current->mm))
+ return 0;
+ exe_file = get_mm_exe_file(current->mm);
if (!exe_file)
return 0;
ino = file_inode(exe_file)->i_ino;
dev = file_inode(exe_file)->i_sb->s_dev;
fput(exe_file);
+
return audit_mark_compare(mark, ino, dev);
}