audit: convert PPIDs to the inital PID namespace.

sys_getppid() returns the parent pid of the current process in its own pid
namespace.  Since audit filters are based in the init pid namespace, a process
could avoid a filter or trigger an unintended one by being in an alternate pid
namespace or log meaningless information.

Switch to task_ppid_nr() for PPIDs to anchor all audit filters in the
init_pid_ns.

(informed by ebiederman's 6c621b7e)
Cc: stable@vger.kernel.org
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>

2 files changed, 3 insertions, 3 deletions

diff --git a/kernel/audit.c b/kernel/audit.c
index 7b44bd47759c..e1e1b2137048 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1819,10 +1819,10 @@ void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
         spin_unlock_irq(&tsk->sighand->siglock);
 
         audit_log_format(ab,
-                         " ppid=%ld pid=%d auid=%u uid=%u gid=%u"
+                         " ppid=%d pid=%d auid=%u uid=%u gid=%u"
                          " euid=%u suid=%u fsuid=%u"
                          " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
-                         sys_getppid(),
+                         task_ppid_nr(tsk),
                          tsk->pid,
                          from_kuid(&init_user_ns, audit_get_loginuid(tsk)),
                          from_kuid(&init_user_ns, cred->uid),
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 57bf178ca7d5..a6cf7ab56e61 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -465,7 +465,7 @@ static int audit_filter_rules(struct task_struct *tsk,
                 case AUDIT_PPID:
                         if (ctx) {
                                 if (!ctx->ppid)
-                                        ctx->ppid = sys_getppid();
+                                        ctx->ppid = task_ppid_nr(tsk);
                                 result = audit_comparator(ctx->ppid, f->op, f->val);
                         }
                         break;