Patch "af_unix: return data from multiple SKBs on recv() with MSG_PEEK flag" has been added to the 3.14-stable tree

Patch "af_unix: return data from multiple SKBs on recv() with MSG_PEEK flag" has been added to the 3.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    af_unix: return data from multiple SKBs on recv() with MSG_PEEK flag

to the 3.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     af_unix-return-data-from-multiple-skbs-on-recv-with-msg_peek-flag.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Oct 22 17:25:59 PDT 2015
From: Aaron Conole <aconole@bytheb.org>
Date: Sat, 26 Sep 2015 18:50:43 -0400
Subject: af_unix: return data from multiple SKBs on recv() with MSG_PEEK flag

From: Aaron Conole <aconole@bytheb.org>

[ Upstream commit 9f389e35674f5b086edd70ed524ca0f287259725 ]

AF_UNIX sockets now return multiple skbs from recv() when MSG_PEEK flag
is set.

This is referenced in kernel bugzilla #12323 @
https://bugzilla.kernel.org/show_bug.cgi?id=12323

As described both in the BZ and lkml thread @
http://lkml.org/lkml/2008/1/8/444 calling recv() with MSG_PEEK on an
AF_UNIX socket only reads a single skb, where the desired effect is
to return as much skb data has been queued, until hitting the recv
buffer size (whichever comes first).

The modified MSG_PEEK path will now move to the next skb in the tree
and jump to the again: label, rather than following the natural loop
structure. This requires duplicating some of the loop head actions.

This was tested using the python socketpair python code attached to
the bugzilla issue.

Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/unix/af_unix.c |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2064,8 +2064,20 @@ again:
 			if (UNIXCB(skb).fp)
 				siocb->scm->fp = scm_fp_dup(UNIXCB(skb).fp);
 
-			sk_peek_offset_fwd(sk, chunk);
+			if (skip) {
+				sk_peek_offset_fwd(sk, chunk);
+				skip -= chunk;
+			}
 
+			if (UNIXCB(skb).fp)
+				break;
+
+			last = skb;
+			unix_state_lock(sk);
+			skb = skb_peek_next(skb, &sk->sk_receive_queue);
+			if (skb)
+				goto again;
+			unix_state_unlock(sk);
 			break;
 		}
 	} while (size);


Patches currently in stable-queue which might be from aconole@bytheb.org are

queue-3.14/af_unix-convert-the-unix_sk-macro-to-an-inline-function-for-type-safety.patch
queue-3.14/af_unix-return-data-from-multiple-skbs-on-recv-with-msg_peek-flag.patch
queue-3.14/net-unix-fix-logic-about-sk_peek_offset.patch