Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760875Ab3D2Tjr (ORCPT ); Mon, 29 Apr 2013 15:39:47 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:60698 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757464Ab3D2TCo (ORCPT ); Mon, 29 Apr 2013 15:02:44 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Karel Srot , Ding Tianhong , "Eric W. Biederman" , "David S. Miller" Subject: [ 26/42] af_unix: If we dont care about credentials coallesce all messages Date: Mon, 29 Apr 2013 12:02:08 -0700 Message-Id: <20130429184755.381019155@linuxfoundation.org> X-Mailer: git-send-email 1.8.1.rc1.5.g7e0651a In-Reply-To: <20130429184752.435249613@linuxfoundation.org> References: <20130429184752.435249613@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2344 Lines: 61 3.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Eric W. Biederman" [ Upstream commit 0e82e7f6dfeec1013339612f74abc2cdd29d43d2 ] It was reported that the following LSB test case failed https://lsbbugs.linuxfoundation.org/attachment.cgi?id=2144 because we were not coallescing unix stream messages when the application was expecting us to. The problem was that the first send was before the socket was accepted and thus sock->sk_socket was NULL in maybe_add_creds, and the second send after the socket was accepted had a non-NULL value for sk->socket and thus we could tell the credentials were not needed so we did not bother. The unnecessary credentials on the first message cause unix_stream_recvmsg to start verifying that all messages had the same credentials before coallescing and then the coallescing failed because the second message had no credentials. Ignoring credentials when we don't care in unix_stream_recvmsg fixes a long standing pessimization which would fail to coallesce messages when reading from a unix stream socket if the senders were different even if we did not care about their credentials. I have tested this and verified that the in the LSB test case mentioned above that the messages do coallesce now, while the were failing to coallesce without this change. Reported-by: Karel Srot Reported-by: Ding Tianhong Signed-off-by: "Eric W. Biederman" Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/unix/af_unix.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1995,7 +1995,7 @@ again: if ((UNIXCB(skb).pid != siocb->scm->pid) || (UNIXCB(skb).cred != siocb->scm->cred)) break; - } else { + } else if (test_bit(SOCK_PASSCRED, &sock->flags)) { /* Copy credentials */ scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred); check_creds = 1; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/