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authorEric W. Biederman <ebiederm@xmission.com>2013-04-03 16:14:47 +0000
committerDavid S. Miller <davem@davemloft.net>2013-04-05 00:49:13 -0400
commit0e82e7f6dfeec1013339612f74abc2cdd29d43d2 (patch)
tree4f6b77bd1cc2a757a119ee131cb0e50ebf872b89 /net/unix
parent25da0e3e9d3fb2b522bc2a598076735850310eb1 (diff)
af_unix: If we don't care about credentials coallesce all messages
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 <ksrot@redhat.com> Reported-by: Ding Tianhong <dingtianhong@huawei.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/unix')
-rw-r--r--net/unix/af_unix.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index f153a8d6e339..2db702d82e7d 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1993,7 +1993,7 @@ 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;

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