[PATCH 1/3] tcp: allow to enable repair mode for sockets in any state

From: Andrey Vagin
Date: Fri Mar 21 2014 - 09:35:31 EST

The repair mode is used for dumping state of tcp connections
(sequence numbers, queues, options, etc).

Currently the repair mode can be enalbed only for sockets in the
TCP_ESTABLISHED state. If a socket in another state, its internal
state can not be dumped.

Same time there is no guarantee that a connection won't be in other
states when we are dumping it, thus to be able to dump and restore
such states we need to get rid of CLOSE,ESTABLISHED in-kernel

I see nothing wrong to allow enabling of the repair mode for connected
sockets in any states.

Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Cc: Hideaki YOSHIFUJI <yoshfuji@xxxxxxxxxxxxxx>
Cc: Patrick McHardy <kaber@xxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Signed-off-by: Andrey Vagin <avagin@xxxxxxxxxx>
net/ipv4/tcp.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 97c8f56..267adb7 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1106,15 +1106,18 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,

if (unlikely(tp->repair)) {
+ err = -EINVAL;
+ if (tp->repair_queue == TCP_NO_QUEUE)
+ goto out_err;
+ if (sk->sk_state != TCP_ESTABLISHED)
+ goto out_err;
if (tp->repair_queue == TCP_RECV_QUEUE) {
copied = tcp_send_rcvq(sk, msg, size);
goto out;

- err = -EINVAL;
- if (tp->repair_queue == TCP_NO_QUEUE)
- goto out_err;
/* 'common' sending to sendq */

@@ -2375,7 +2378,7 @@ void tcp_sock_destruct(struct sock *sk)
static inline bool tcp_can_repair_sock(const struct sock *sk)
return ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN) &&
- ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_ESTABLISHED));
+ (sk->sk_state != TCP_LISTEN);

static int tcp_repair_options_est(struct tcp_sock *tp,

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