audit: convert PPIDs to the inital PID namespace.

commit c92cdeb45eea38515e82187f48c2e4f435fb4e25 upstream.

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: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[bwh: Backported to 3.2: sys_getppid() is used by audit_exit() but not
 audit_log_task_info()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 47b7fc1ea8935aebcf306ea54caf969274dfa7c8..aeac7cccd5e95acc188766cc4718402425f6f1c9 100644 (file)
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -473,7 +473,7 @@ 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;
@@ -1335,7 +1335,7 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
        /* tsk == current */
        context->pid = tsk->pid;
        if (!context->ppid)
-               context->ppid = sys_getppid();
+               context->ppid = task_ppid_nr(tsk);
        cred = current_cred();
        context->uid   = cred->uid;
        context->gid   = cred->gid;