[TCP]: Invoke tcp_sendmsg() directly, do not use inet_sendmsg().

As discovered by Evegniy Polyakov, if we try to sendmsg after
a connection reset, we can do incredibly stupid things.

The core issue is that inet_sendmsg() tries to autobind the
socket, but we should never do that for TCP.  Instead we should
just go straight into TCP's sendmsg() code which will do all
of the necessary state and pending socket error checks.

TCP's sendpage already directly vectors to tcp_sendpage(), so this
merely brings sendmsg() in line with that.

Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 5 insertions, 6 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index c209361ab74a..185c7ecce4cc 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -281,7 +281,7 @@ extern int			tcp_v4_remember_stamp(struct sock *sk);
 
 extern int                      tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
 
-extern int                      tcp_sendmsg(struct kiocb *iocb, struct sock *sk,
+extern int                      tcp_sendmsg(struct kiocb *iocb, struct socket *sock,
                                             struct msghdr *msg, size_t size);
 extern ssize_t                  tcp_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags);
 
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 06c08e5740fb..e68103475cca 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -831,7 +831,7 @@ const struct proto_ops inet_stream_ops = {
         .shutdown          = inet_shutdown,
         .setsockopt        = sock_common_setsockopt,
         .getsockopt        = sock_common_getsockopt,
-        .sendmsg           = inet_sendmsg,
+        .sendmsg           = tcp_sendmsg,
         .recvmsg           = sock_common_recvmsg,
         .mmap              = sock_no_mmap,
         .sendpage          = tcp_sendpage,
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index da4c0b6ab79a..7e740112b238 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -658,9 +658,10 @@ static inline int select_size(struct sock *sk)
         return tmp;
 }
 
-int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
+int tcp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
                 size_t size)
 {
+        struct sock *sk = sock->sk;
         struct iovec *iov;
         struct tcp_sock *tp = tcp_sk(sk);
         struct sk_buff *skb;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 3f5f7423b95c..9c94627c8c7e 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2425,7 +2425,6 @@ struct proto tcp_prot = {
         .shutdown               = tcp_shutdown,
         .setsockopt             = tcp_setsockopt,
         .getsockopt             = tcp_getsockopt,
-        .sendmsg                = tcp_sendmsg,
         .recvmsg                = tcp_recvmsg,
         .backlog_rcv            = tcp_v4_do_rcv,
         .hash                   = tcp_v4_hash,
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index eed09373a45d..b5f96372ad73 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -484,7 +484,7 @@ const struct proto_ops inet6_stream_ops = {
         .shutdown          = inet_shutdown,             /* ok           */
         .setsockopt        = sock_common_setsockopt,    /* ok           */
         .getsockopt        = sock_common_getsockopt,    /* ok           */
-        .sendmsg           = inet_sendmsg,              /* ok           */
+        .sendmsg           = tcp_sendmsg,               /* ok           */
         .recvmsg           = sock_common_recvmsg,       /* ok           */
         .mmap              = sock_no_mmap,
         .sendpage          = tcp_sendpage,
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index f10f3689d671..cbdb78487915 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -2115,7 +2115,6 @@ struct proto tcpv6_prot = {
         .shutdown               = tcp_shutdown,
         .setsockopt             = tcp_setsockopt,
         .getsockopt             = tcp_getsockopt,
-        .sendmsg                = tcp_sendmsg,
         .recvmsg                = tcp_recvmsg,
         .backlog_rcv            = tcp_v6_do_rcv,
         .hash                   = tcp_v6_hash,