7 files changed, 92 insertions, 12 deletions

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index e1e021594cff..03964e088180 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -468,6 +468,17 @@ tcp_syncookies - BOOLEAN
         SYN flood warnings in logs not being really flooded, your server
         is seriously misconfigured.
 
+tcp_fastopen - INTEGER
+        Enable TCP Fast Open feature (draft-ietf-tcpm-fastopen) to send data
+        in the opening SYN packet. To use this feature, the client application
+        must not use connect(). Instead, it should use sendmsg() or sendto()
+        with MSG_FASTOPEN flag which performs a TCP handshake automatically.
+
+        The values (bitmap) are:
+        1: Enables sending data in the opening SYN on the client
+
+        Default: 0
+
 tcp_syn_retries - INTEGER
         Number of times initial SYNs for an active TCP connection attempt
         will be retransmitted. Should not be higher than 255. Default value
diff --git a/include/linux/socket.h b/include/linux/socket.h
index 25d6322fb635..ba7b2e817cfa 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -268,6 +268,7 @@ struct ucred {
 #define MSG_SENDPAGE_NOTLAST 0x20000 /* sendpage() internal : not the last page */
 #define MSG_EOF         MSG_FIN
 
+#define MSG_FASTOPEN    0x20000000      /* Send data in TCP SYN */
 #define MSG_CMSG_CLOEXEC 0x40000000     /* Set close_on_exit for file
                                            descriptor received through
                                            SCM_RIGHTS */
diff --git a/include/net/inet_common.h b/include/net/inet_common.h
index 22fac9892b16..234008782c8c 100644
--- a/include/net/inet_common.h
+++ b/include/net/inet_common.h
@@ -14,9 +14,11 @@ struct sockaddr;
 struct socket;
 
 extern int inet_release(struct socket *sock);
-extern int inet_stream_connect(struct socket *sock, struct sockaddr * uaddr,
+extern int inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
                                int addr_len, int flags);
-extern int inet_dgram_connect(struct socket *sock, struct sockaddr * uaddr,
+extern int __inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
+                                 int addr_len, int flags);
+extern int inet_dgram_connect(struct socket *sock, struct sockaddr *uaddr,
                               int addr_len, int flags);
 extern int inet_accept(struct socket *sock, struct socket *newsock, int flags);
 extern int inet_sendmsg(struct kiocb *iocb, struct socket *sock,
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 867557b4244a..c0258100d70c 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -212,6 +212,9 @@ extern void tcp_time_wait(struct sock *sk, int state, int timeo);
 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
 #define TCP_INIT_CWND           10
 
+/* Bit Flags for sysctl_tcp_fastopen */
+#define TFO_CLIENT_ENABLE       1
+
 extern struct inet_timewait_death_row tcp_death_row;
 
 /* sysctl variables for tcp */
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index edc414625be2..fe4582ca969a 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -585,8 +585,8 @@ static long inet_wait_for_connect(struct sock *sk, long timeo, int writebias)
  *      Connect to a remote host. There is regrettably still a little
  *      TCP 'magic' in here.
  */
-int inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
-                        int addr_len, int flags)
+int __inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
+                          int addr_len, int flags)
 {
         struct sock *sk = sock->sk;
         int err;
@@ -595,8 +595,6 @@ int inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
         if (addr_len < sizeof(uaddr->sa_family))
                 return -EINVAL;
 
-        lock_sock(sk);
-
         if (uaddr->sa_family == AF_UNSPEC) {
                 err = sk->sk_prot->disconnect(sk, flags);
                 sock->state = err ? SS_DISCONNECTING : SS_UNCONNECTED;
@@ -663,7 +661,6 @@ int inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
         sock->state = SS_CONNECTED;
         err = 0;
 out:
-        release_sock(sk);
         return err;
 
 sock_error:
@@ -673,6 +670,18 @@ sock_error:
                 sock->state = SS_DISCONNECTING;
         goto out;
 }
+EXPORT_SYMBOL(__inet_stream_connect);
+
+int inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
+                        int addr_len, int flags)
+{
+        int err;
+
+        lock_sock(sock->sk);
+        err = __inet_stream_connect(sock, uaddr, addr_len, flags);
+        release_sock(sock->sk);
+        return err;
+}
 EXPORT_SYMBOL(inet_stream_connect);
 
 /*
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 4252cd8f39fd..581ecf02c6b5 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -270,6 +270,7 @@
 #include <linux/slab.h>
 
 #include <net/icmp.h>
+#include <net/inet_common.h>
 #include <net/tcp.h>
 #include <net/xfrm.h>
 #include <net/ip.h>
@@ -982,26 +983,67 @@ static inline int select_size(const struct sock *sk, bool sg)
         return tmp;
 }
 
+void tcp_free_fastopen_req(struct tcp_sock *tp)
+{
+        if (tp->fastopen_req != NULL) {
+                kfree(tp->fastopen_req);
+                tp->fastopen_req = NULL;
+        }
+}
+
+static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *size)
+{
+        struct tcp_sock *tp = tcp_sk(sk);
+        int err, flags;
+
+        if (!(sysctl_tcp_fastopen & TFO_CLIENT_ENABLE))
+                return -EOPNOTSUPP;
+        if (tp->fastopen_req != NULL)
+                return -EALREADY; /* Another Fast Open is in progress */
+
+        tp->fastopen_req = kzalloc(sizeof(struct tcp_fastopen_request),
+                                   sk->sk_allocation);
+        if (unlikely(tp->fastopen_req == NULL))
+                return -ENOBUFS;
+        tp->fastopen_req->data = msg;
+
+        flags = (msg->msg_flags & MSG_DONTWAIT) ? O_NONBLOCK : 0;
+        err = __inet_stream_connect(sk->sk_socket, msg->msg_name,
+                                    msg->msg_namelen, flags);
+        *size = tp->fastopen_req->copied;
+        tcp_free_fastopen_req(tp);
+        return err;
+}
+
 int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                 size_t size)
 {
         struct iovec *iov;
         struct tcp_sock *tp = tcp_sk(sk);
         struct sk_buff *skb;
-        int iovlen, flags, err, copied;
-        int mss_now = 0, size_goal;
+        int iovlen, flags, err, copied = 0;
+        int mss_now = 0, size_goal, copied_syn = 0, offset = 0;
         bool sg;
         long timeo;
 
         lock_sock(sk);
 
         flags = msg->msg_flags;
+        if (flags & MSG_FASTOPEN) {
+                err = tcp_sendmsg_fastopen(sk, msg, &copied_syn);
+                if (err == -EINPROGRESS && copied_syn > 0)
+                        goto out;
+                else if (err)
+                        goto out_err;
+                offset = copied_syn;
+        }
+
         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 
         /* Wait for a connection to finish. */
         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
-                        goto out_err;
+                        goto do_error;
 
         if (unlikely(tp->repair)) {
                 if (tp->repair_queue == TCP_RECV_QUEUE) {
@@ -1037,6 +1079,15 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                 unsigned char __user *from = iov->iov_base;
 
                 iov++;
+                if (unlikely(offset > 0)) {  /* Skip bytes copied in SYN */
+                        if (offset >= seglen) {
+                                offset -= seglen;
+                                continue;
+                        }
+                        seglen -= offset;
+                        from += offset;
+                        offset = 0;
+                }
 
                 while (seglen > 0) {
                         int copy = 0;
@@ -1199,7 +1250,7 @@ out:
         if (copied && likely(!tp->repair))
                 tcp_push(sk, flags, mss_now, tp->nonagle);
         release_sock(sk);
-        return copied;
+        return copied + copied_syn;
 
 do_fault:
         if (!skb->len) {
@@ -1212,7 +1263,7 @@ do_fault:
         }
 
 do_error:
-        if (copied)
+        if (copied + copied_syn)
                 goto out;
 out_err:
         err = sk_stream_error(sk, flags, err);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 01aa77a97020..1d8b75a58981 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1952,6 +1952,9 @@ void tcp_v4_destroy_sock(struct sock *sk)
                 tp->cookie_values = NULL;
         }
 
+        /* If socket is aborted during connect operation */
+        tcp_free_fastopen_req(tp);
+
         sk_sockets_allocated_dec(sk);
         sock_release_memcg(sk);
 }