From: Alexander Mikhalitsyn aleksandr.mikhalitsyn@canonical.com
[ Upstream commit a02d83f9947d8f71904eda4de046630c3eb6802c ]
Currently, kernel would set MSG_CTRUNC flag if msg_control buffer wasn't provided and SO_PASSCRED was set or if there was pending SCM_RIGHTS.
For some reason we have no corresponding check for SO_PASSSEC.
In the recvmsg(2) doc we have: MSG_CTRUNC indicates that some control data was discarded due to lack of space in the buffer for ancillary data.
So, we need to set MSG_CTRUNC flag for all types of SCM.
This change can break applications those don't check MSG_CTRUNC flag.
Cc: "David S. Miller" davem@davemloft.net Cc: Eric Dumazet edumazet@google.com Cc: Jakub Kicinski kuba@kernel.org Cc: Paolo Abeni pabeni@redhat.com Cc: Leon Romanovsky leon@kernel.org Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Alexander Mikhalitsyn aleksandr.mikhalitsyn@canonical.com
v2: - commit message was rewritten according to Eric's suggestion Acked-by: Paul Moore paul@paul-moore.com
Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/scm.h | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/include/net/scm.h b/include/net/scm.h index 903771c8d4e33..1268a051f1aa2 100644 --- a/include/net/scm.h +++ b/include/net/scm.h @@ -104,16 +104,27 @@ static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct sc } } } + +static inline bool scm_has_secdata(struct socket *sock) +{ + return test_bit(SOCK_PASSSEC, &sock->flags); +} #else static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm) { } + +static inline bool scm_has_secdata(struct socket *sock) +{ + return false; +} #endif /* CONFIG_SECURITY_NETWORK */
static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm, int flags) { if (!msg->msg_control) { - if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp) + if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp || + scm_has_secdata(sock)) msg->msg_flags |= MSG_CTRUNC; scm_destroy(scm); return;