sock: ignore SCM_RIGHTS and SCM_CREDENTIALS in __sock_cmsg_send

Sergei Trofimovich reported that pulse audio sends SCM_CREDENTIALS
as a control message to TCP. Since __sock_cmsg_send does not
support SCM_RIGHTS and SCM_CREDENTIALS, it returns an error and
hence breaks pulse audio over TCP.

SCM_RIGHTS and SCM_CREDENTIALS are sent on the SOL_SOCKET layer
but they semantically belong to SOL_UNIX. Since all
cmsg-processing functions including sock_cmsg_send ignore control
messages of other layers, it is best to ignore SCM_RIGHTS
and SCM_CREDENTIALS for consistency (and also for fixing pulse
audio over TCP).

Fixes: c14ac9451c34 ("sock: enable timestamping using control messages")
Signed-off-by: Soheil Hassas Yeganeh <[email protected]>
Reported-by: Sergei Trofimovich <[email protected]>
Tested-by: Sergei Trofimovich <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Willem de Bruijn <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

diff --git a/net/core/sock.c b/net/core/sock.c
index 08bf97eceeb3827d0b237d8c01910e5e0a0f5d6a..b7f12639c26ae409d911c3a593d475b1bd9cc6dd 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1938,6 +1938,10 @@ int __sock_cmsg_send(struct sock *sk, struct msghdr *msg, struct cmsghdr *cmsg,
                sockc->tsflags &= ~SOF_TIMESTAMPING_TX_RECORD_MASK;
                sockc->tsflags |= tsflags;
                break;
+       /* SCM_RIGHTS and SCM_CREDENTIALS are semantically in SOL_UNIX. */
+       case SCM_RIGHTS:
+       case SCM_CREDENTIALS:
+               break;
        default:
                return -EINVAL;
        }