2 files changed, 33 insertions, 24 deletions

diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index 20725e2..90c9e28 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -23,7 +23,8 @@ struct unix_address {
 };
 
 struct unix_skb_parms {
-	struct ucred		creds;		/* Skb credentials	*/
+	struct pid		*pid;		/* Skb credentials	*/
+	const struct cred	*cred;
 	struct scm_fp_list	*fp;		/* Passed files		*/
 #ifdef CONFIG_SECURITY_NETWORK
 	u32			secid;		/* Security ID		*/
@@ -31,7 +32,6 @@ struct unix_skb_parms {
 };
 
 #define UNIXCB(skb) 	(*(struct unix_skb_parms *)&((skb)->cb))
-#define UNIXCREDS(skb)	(&UNIXCB((skb)).creds)
 #define UNIXSID(skb)	(&UNIXCB((skb)).secid)
 
 #define unix_state_lock(s)	spin_lock(&unix_sk(s)->lock)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index e1f1349..5fe9d6f 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1316,18 +1316,20 @@ static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
 	int i;
 
 	scm->fp = UNIXCB(skb).fp;
-	skb->destructor = sock_wfree;
 	UNIXCB(skb).fp = NULL;
 
 	for (i = scm->fp->count-1; i >= 0; i--)
 		unix_notinflight(scm->fp->fp[i]);
 }
 
-static void unix_destruct_fds(struct sk_buff *skb)
+static void unix_destruct_scm(struct sk_buff *skb)
 {
 	struct scm_cookie scm;
 	memset(&scm, 0, sizeof(scm));
-	unix_detach_fds(&scm, skb);
+	scm.pid  = UNIXCB(skb).pid;
+	scm.cred = UNIXCB(skb).cred;
+	if (UNIXCB(skb).fp)
+		unix_detach_fds(&scm, skb);
 
 	/* Alas, it calls VFS */
 	/* So fscking what? fput() had been SMP-safe since the last Summer */
@@ -1350,10 +1352,22 @@ static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
 
 	for (i = scm->fp->count-1; i >= 0; i--)
 		unix_inflight(scm->fp->fp[i]);
-	skb->destructor = unix_destruct_fds;
 	return 0;
 }
 
+static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
+{
+	int err = 0;
+	UNIXCB(skb).pid  = get_pid(scm->pid);
+	UNIXCB(skb).cred = get_cred(scm->cred);
+	UNIXCB(skb).fp = NULL;
+	if (scm->fp && send_fds)
+		err = unix_attach_fds(scm, skb);
+
+	skb->destructor = unix_destruct_scm;
+	return err;
+}
+
 /*
  *	Send AF_UNIX data.
  */
@@ -1410,12 +1424,9 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
 	if (skb == NULL)
 		goto out;
 
-	memcpy(UNIXCREDS(skb), &siocb->scm->creds, sizeof(struct ucred));
-	if (siocb->scm->fp) {
-		err = unix_attach_fds(siocb->scm, skb);
-		if (err)
-			goto out_free;
-	}
+	err = unix_scm_to_skb(siocb->scm, skb, true);
+	if (err)
+		goto out_free;
 	unix_get_secdata(siocb->scm, skb);
 
 	skb_reset_transport_header(skb);
@@ -1585,16 +1596,14 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
 		 */
 		size = min_t(int, size, skb_tailroom(skb));
 
-		memcpy(UNIXCREDS(skb), &siocb->scm->creds, sizeof(struct ucred));
+
 		/* Only send the fds in the first buffer */
-		if (siocb->scm->fp && !fds_sent) {
-			err = unix_attach_fds(siocb->scm, skb);
-			if (err) {
-				kfree_skb(skb);
-				goto out_err;
-			}
-			fds_sent = true;
+		err = unix_scm_to_skb(siocb->scm, skb, !fds_sent);
+		if (err) {
+			kfree_skb(skb);
+			goto out_err;
 		}
+		fds_sent = true;
 
 		err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
 		if (err) {
@@ -1711,7 +1720,7 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
 		siocb->scm = &tmp_scm;
 		memset(&tmp_scm, 0, sizeof(tmp_scm));
 	}
-	siocb->scm->creds = *UNIXCREDS(skb);
+	scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
 	unix_set_secdata(siocb->scm, skb);
 
 	if (!(flags & MSG_PEEK)) {
@@ -1860,14 +1869,14 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 
 		if (check_creds) {
 			/* Never glue messages from different writers */
-			if (memcmp(UNIXCREDS(skb), &siocb->scm->creds,
-				   sizeof(siocb->scm->creds)) != 0) {
+			if ((UNIXCB(skb).pid  != siocb->scm->pid) ||
+			    (UNIXCB(skb).cred != siocb->scm->cred)) {
 				skb_queue_head(&sk->sk_receive_queue, skb);
 				break;
 			}
 		} else {
 			/* Copy credentials */
-			siocb->scm->creds = *UNIXCREDS(skb);
+			scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
 			check_creds = 1;
 		}