1 files changed, 44 insertions, 8 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 85d3bb7490aa..8ee85aa79fa7 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -530,6 +530,16 @@ static int unix_seqpacket_sendmsg(struct kiocb *, struct socket *,
 static int unix_seqpacket_recvmsg(struct kiocb *, struct socket *,
 				  struct msghdr *, size_t, int);
 
+static void unix_set_peek_off(struct sock *sk, int val)
+{
+	struct unix_sock *u = unix_sk(sk);
+
+	mutex_lock(&u->readlock);
+	sk->sk_peek_off = val;
+	mutex_unlock(&u->readlock);
+}
+
+
 static const struct proto_ops unix_stream_ops = {
 	.family =	PF_UNIX,
 	.owner =	THIS_MODULE,
@@ -549,6 +559,7 @@ static const struct proto_ops unix_stream_ops = {
 	.recvmsg =	unix_stream_recvmsg,
 	.mmap =		sock_no_mmap,
 	.sendpage =	sock_no_sendpage,
+	.set_peek_off =	unix_set_peek_off,
 };
 
 static const struct proto_ops unix_dgram_ops = {
@@ -570,6 +581,7 @@ static const struct proto_ops unix_dgram_ops = {
 	.recvmsg =	unix_dgram_recvmsg,
 	.mmap =		sock_no_mmap,
 	.sendpage =	sock_no_sendpage,
+	.set_peek_off =	unix_set_peek_off,
 };
 
 static const struct proto_ops unix_seqpacket_ops = {
@@ -591,6 +603,7 @@ static const struct proto_ops unix_seqpacket_ops = {
 	.recvmsg =	unix_seqpacket_recvmsg,
 	.mmap =		sock_no_mmap,
 	.sendpage =	sock_no_sendpage,
+	.set_peek_off =	unix_set_peek_off,
 };
 
 static struct proto unix_proto = {
@@ -1756,6 +1769,7 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
 	int noblock = flags & MSG_DONTWAIT;
 	struct sk_buff *skb;
 	int err;
+	int peeked, skip;
 
 	err = -EOPNOTSUPP;
 	if (flags&MSG_OOB)
@@ -1769,7 +1783,9 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
 		goto out;
 	}
 
-	skb = skb_recv_datagram(sk, flags, noblock, &err);
+	skip = sk_peek_offset(sk, flags);
+
+	skb = __skb_recv_datagram(sk, flags, &peeked, &skip, &err);
 	if (!skb) {
 		unix_state_lock(sk);
 		/* Signal EOF on disconnected non-blocking SEQPACKET socket. */
@@ -1786,12 +1802,12 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
 	if (msg->msg_name)
 		unix_copy_addr(msg, skb->sk);
 
-	if (size > skb->len)
-		size = skb->len;
-	else if (size < skb->len)
+	if (size > skb->len - skip)
+		size = skb->len - skip;
+	else if (size < skb->len - skip)
 		msg->msg_flags |= MSG_TRUNC;
 
-	err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, size);
+	err = skb_copy_datagram_iovec(skb, skip, msg->msg_iov, size);
 	if (err)
 		goto out_free;
 
@@ -1808,6 +1824,8 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
 	if (!(flags & MSG_PEEK)) {
 		if (UNIXCB(skb).fp)
 			unix_detach_fds(siocb->scm, skb);
+
+		sk_peek_offset_bwd(sk, skb->len);
 	} else {
 		/* It is questionable: on PEEK we could:
 		   - do not return fds - good, but too simple 8)
@@ -1821,10 +1839,13 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
 		   clearly however!
 
 		*/
+
+		sk_peek_offset_fwd(sk, size);
+
 		if (UNIXCB(skb).fp)
 			siocb->scm->fp = scm_fp_dup(UNIXCB(skb).fp);
 	}
-	err = size;
+	err = (flags & MSG_TRUNC) ? skb->len - skip : size;
 
 	scm_recv(sock, msg, siocb->scm, flags);
 
@@ -1884,6 +1905,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 	int target;
 	int err = 0;
 	long timeo;
+	int skip;
 
 	err = -EINVAL;
 	if (sk->sk_state != TCP_ESTABLISHED)
@@ -1913,12 +1935,15 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 		goto out;
 	}
 
+	skip = sk_peek_offset(sk, flags);
+
 	do {
 		int chunk;
 		struct sk_buff *skb;
 
 		unix_state_lock(sk);
 		skb = skb_peek(&sk->sk_receive_queue);
+again:
 		if (skb == NULL) {
 			unix_sk(sk)->recursion_level = 0;
 			if (copied >= target)
@@ -1953,6 +1978,13 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 			unix_state_unlock(sk);
 			break;
 		}
+
+		if (skip >= skb->len) {
+			skip -= skb->len;
+			skb = skb_peek_next(skb, &sk->sk_receive_queue);
+			goto again;
+		}
+
 		unix_state_unlock(sk);
 
 		if (check_creds) {
@@ -1972,8 +2004,8 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 			sunaddr = NULL;
 		}
 
-		chunk = min_t(unsigned int, skb->len, size);
-		if (memcpy_toiovec(msg->msg_iov, skb->data, chunk)) {
+		chunk = min_t(unsigned int, skb->len - skip, size);
+		if (memcpy_toiovec(msg->msg_iov, skb->data + skip, chunk)) {
 			if (copied == 0)
 				copied = -EFAULT;
 			break;
@@ -1985,6 +2017,8 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 		if (!(flags & MSG_PEEK)) {
 			skb_pull(skb, chunk);
 
+			sk_peek_offset_bwd(sk, chunk);
+
 			if (UNIXCB(skb).fp)
 				unix_detach_fds(siocb->scm, skb);
 
@@ -2002,6 +2036,8 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 			if (UNIXCB(skb).fp)
 				siocb->scm->fp = scm_fp_dup(UNIXCB(skb).fp);
 
+			sk_peek_offset_fwd(sk, chunk);
+
 			break;
 		}
 	} while (size);