audit: update shutdown LSM data

The audit process LSM information is changed from a secid audit_sig_sid
to an lsm_prop in audit_sig_lsm. Update the users of this data
appropriately. Calls to security_secid_to_secctx() are changed to use
security_lsmprop_to_secctx() instead. security_current_getsecid_subj()
is scaffolded. It will be updated in a subsequent patch.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>

kernel/audit.c

@@ -123,7 +123,7 @@ static u32	audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
 /* The identity of the user shutting down the audit system. */
 static kuid_t		audit_sig_uid = INVALID_UID;
 static pid_t		audit_sig_pid = -1;
-static u32		audit_sig_sid;
+static struct lsm_prop	audit_sig_lsm;
 
 /* Records can be lost in several ways:
    0) [suppressed in audit_alloc]
@@ -1473,20 +1473,21 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 	}
 	case AUDIT_SIGNAL_INFO:
 		len = 0;
-		if (audit_sig_sid) {
-			err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
+		if (lsmprop_is_set(&audit_sig_lsm)) {
+			err = security_lsmprop_to_secctx(&audit_sig_lsm, &ctx,
+							 &len);
 			if (err)
 				return err;
 		}
 		sig_data = kmalloc(struct_size(sig_data, ctx, len), GFP_KERNEL);
 		if (!sig_data) {
-			if (audit_sig_sid)
+			if (lsmprop_is_set(&audit_sig_lsm))
 				security_release_secctx(ctx, len);
 			return -ENOMEM;
 		}
 		sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
 		sig_data->pid = audit_sig_pid;
-		if (audit_sig_sid) {
+		if (lsmprop_is_set(&audit_sig_lsm)) {
 			memcpy(sig_data->ctx, ctx, len);
 			security_release_secctx(ctx, len);
 		}
@@ -2404,7 +2405,8 @@ int audit_signal_info(int sig, struct task_struct *t)
 			audit_sig_uid = auid;
 		else
 			audit_sig_uid = uid;
-		security_current_getsecid_subj(&audit_sig_sid);
+		/* scaffolding */
+		security_current_getsecid_subj(&audit_sig_lsm.scaffold.secid);
 	}
 
 	return audit_signal_info_syscall(t);