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tcp: Initial repair mode

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This includes (according the the previous description):

* TCP_REPAIR sockoption

This one just puts the socket in/out of the repair mode.
Allowed for CAP_NET_ADMIN and for closed/establised sockets only.
When repair mode is turned off and the socket happens to be in
the established state the window probe is sent to the peer to
'unlock' the connection.

* TCP_REPAIR_QUEUE sockoption

This one sets the queue which we're about to repair. The
'no-queue' is set by default.

* TCP_QUEUE_SEQ socoption

Sets the write_seq/rcv_nxt of a selected repaired queue.
Allowed for TCP_CLOSE-d sockets only. When the socket changes
its state the other seq-s are changed by the kernel according
to the protocol rules (most of the existing code is actually
reused).

* Ability to forcibly bind a socket to a port

The sk->sk_reuse is set to SK_FORCE_REUSE.

* Immediate connect modification

The connect syscall initializes the connection, then directly jumps
to the code which finalizes it.

* Silent close modification

The close just aborts the connection (similar to SO_LINGER with 0
time) but without sending any FIN/RST-s to peer.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Pavel Emelyanov
2012-04-19 03:40:39 +00:00
committed by David S. Miller
parent 370816aef0
commit ee9952831c
5 changed files with 111 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

68
net/ipv4/tcp.c
View File

@@ -1935,7 +1935,9 @@ void tcp_close(struct sock *sk, long timeout)
* advertise a zero window, then kill -9 the FTP client, wheee...
* Note: timeout is always zero in such a case.
*/
if (data_was_unread) {
if (unlikely(tcp_sk(sk)->repair)) {
sk->sk_prot->disconnect(sk, 0);
} else if (data_was_unread) {
/* Unread data was tossed, zap the connection. */
NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
tcp_set_state(sk, TCP_CLOSE);
@@ -2074,6 +2076,8 @@ int tcp_disconnect(struct sock *sk, int flags)
/* ABORT function of RFC793 */
if (old_state == TCP_LISTEN) {
inet_csk_listen_stop(sk);
} else if (unlikely(tp->repair)) {
sk->sk_err = ECONNABORTED;
} else if (tcp_need_reset(old_state) ||
(tp->snd_nxt != tp->write_seq &&
(1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
@@ -2125,6 +2129,12 @@ int tcp_disconnect(struct sock *sk, int flags)
}
EXPORT_SYMBOL(tcp_disconnect);
static inline int tcp_can_repair_sock(struct sock *sk)
{
return capable(CAP_NET_ADMIN) &&
((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_ESTABLISHED));
}
/*
* Socket option code for TCP.
*/
@@ -2297,6 +2307,42 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
tp->thin_dupack = val;
break;
case TCP_REPAIR:
if (!tcp_can_repair_sock(sk))
err = -EPERM;
else if (val == 1) {
tp->repair = 1;
sk->sk_reuse = SK_FORCE_REUSE;
tp->repair_queue = TCP_NO_QUEUE;
} else if (val == 0) {
tp->repair = 0;
sk->sk_reuse = SK_NO_REUSE;
tcp_send_window_probe(sk);
} else
err = -EINVAL;
break;
case TCP_REPAIR_QUEUE:
if (!tp->repair)
err = -EPERM;
else if (val < TCP_QUEUES_NR)
tp->repair_queue = val;
else
err = -EINVAL;
break;
case TCP_QUEUE_SEQ:
if (sk->sk_state != TCP_CLOSE)
err = -EPERM;
else if (tp->repair_queue == TCP_SEND_QUEUE)
tp->write_seq = val;
else if (tp->repair_queue == TCP_RECV_QUEUE)
tp->rcv_nxt = val;
else
err = -EINVAL;
break;
case TCP_CORK:
/* When set indicates to always queue non-full frames.
* Later the user clears this option and we transmit
@@ -2632,6 +2678,26 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
val = tp->thin_dupack;
break;
case TCP_REPAIR:
val = tp->repair;
break;
case TCP_REPAIR_QUEUE:
if (tp->repair)
val = tp->repair_queue;
else
return -EINVAL;
break;
case TCP_QUEUE_SEQ:
if (tp->repair_queue == TCP_SEND_QUEUE)
val = tp->write_seq;
else if (tp->repair_queue == TCP_RECV_QUEUE)
val = tp->rcv_nxt;
else
return -EINVAL;
break;
case TCP_USER_TIMEOUT:
val = jiffies_to_msecs(icsk->icsk_user_timeout);
break;