Audit: do not print error when LSMs disabled

RHBZ: 785936

If the audit system collects a record about one process sending a signal
to another process it includes in that collection the 'secid' or 'an int
used to represet an LSM label.'  If there is no LSM enabled it will
collect a 0.  The problem is that when we attempt to print that record
we ask the LSM to convert the secid back to a string.  Since there is no
LSM it returns EOPNOTSUPP.

Most code in the audit system checks if the secid is 0 and does not
print LSM info in that case.  The signal information code however forgot
that check.  Thus users will see a message in syslog indicating that
converting the sid to string failed.  Add the right check.

Signed-off-by: Eric Paris <eparis@redhat.com>

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index b536d22fe56f2540926c2a7a84593d446176e24e..67df4ee1d3b6e8eccb06d8b8749946a92dd276e2 100644 (file)
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1205,12 +1205,14 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
        audit_log_format(ab, "opid=%d oauid=%d ouid=%d oses=%d", pid,
                         from_kuid(&init_user_ns, auid),
                         from_kuid(&init_user_ns, uid), sessionid);
-       if (security_secid_to_secctx(sid, &ctx, &len)) {
-               audit_log_format(ab, " obj=(none)");
-               rc = 1;
-       } else {
-               audit_log_format(ab, " obj=%s", ctx);
-               security_release_secctx(ctx, len);
+       if (sid) {
+               if (security_secid_to_secctx(sid, &ctx, &len)) {
+                       audit_log_format(ab, " obj=(none)");
+                       rc = 1;
+               } else {
+                       audit_log_format(ab, " obj=%s", ctx);
+                       security_release_secctx(ctx, len);
+               }
        }
        audit_log_format(ab, " ocomm=");
        audit_log_untrustedstring(ab, comm);