@@ -115,12 +115,22 @@ enum {
#define TCP_CC_INFO 26 /* Get Congestion Control (optional) info */
#define TCP_SAVE_SYN 27 /* Record SYN headers for new connections */
#define TCP_SAVED_SYN 28 /* Get SYN headers recorded for connection */
+#define TCP_REPAIR_WINDOW 29 /* Get/set window parameters */
struct tcp_repair_opt {
__u32 opt_code;
__u32 opt_val;
};
+struct tcp_repair_window {
+ __u32 snd_wl1;
+ __u32 snd_wnd;
+ __u32 max_window;
+
+ __u32 rcv_wnd;
+ __u32 rcv_wup;
+};
+
enum {
TCP_NO_QUEUE,
TCP_RECV_QUEUE,
@@ -2277,6 +2277,38 @@ static inline bool tcp_can_repair_sock(const struct sock *sk)
((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_ESTABLISHED));
}
+static int tcp_repair_set_window(struct tcp_sock *tp, char __user *optbuf, int len)
+{
+ struct tcp_repair_window opt;
+
+ if (!tp->repair)
+ return -EPERM;
+
+ if (len != sizeof(opt))
+ return -EINVAL;
+
+ if (copy_from_user(&opt, optbuf, sizeof(opt)))
+ return -EFAULT;
+
+ if (opt.max_window < opt.snd_wnd)
+ return -EINVAL;
+
+ if (after(opt.snd_wl1, tp->rcv_nxt + opt.rcv_wnd))
+ return -EINVAL;
+
+ if (after(opt.rcv_wup, tp->rcv_nxt))
+ return -EINVAL;
+
+ tp->snd_wl1 = opt.snd_wl1;
+ tp->snd_wnd = opt.snd_wnd;
+ tp->max_window = opt.max_window;
+
+ tp->rcv_wnd = opt.rcv_wnd;
+ tp->rcv_wup = opt.rcv_wup;
+
+ return 0;
+}
+
static int tcp_repair_options_est(struct tcp_sock *tp,
struct tcp_repair_opt __user *optbuf, unsigned int len)
{
@@ -2604,6 +2636,9 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
else
tp->tsoffset = val - tcp_time_stamp;
break;
+ case TCP_REPAIR_WINDOW:
+ err = tcp_repair_set_window(tp, optval, optlen);
+ break;
case TCP_NOTSENT_LOWAT:
tp->notsent_lowat = val;
sk->sk_write_space(sk);
@@ -2860,6 +2895,28 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
return -EINVAL;
break;
+ case TCP_REPAIR_WINDOW: {
+ struct tcp_repair_window opt;
+
+ if (get_user(len, optlen))
+ return -EFAULT;
+
+ if (len != sizeof(opt))
+ return -EINVAL;
+
+ if (!tp->repair)
+ return -EPERM;
+
+ opt.snd_wl1 = tp->snd_wl1;
+ opt.snd_wnd = tp->snd_wnd;
+ opt.max_window = tp->max_window;
+ opt.rcv_wnd = tp->rcv_wnd;
+ opt.rcv_wup = tp->rcv_wup;
+
+ if (copy_to_user(optval, &opt, len))
+ return -EFAULT;
+ return 0;
+ }
case TCP_QUEUE_SEQ:
if (tp->repair_queue == TCP_SEND_QUEUE)
val = tp->write_seq;
We found that sometimes a restored tcp socket doesn't work. A reason of this bug is incorrect window parameters and in this case tcp_acceptable_seq() returns tcp_wnd_end(tp) instead of tp->snd_nxt. The other side drops packets with this seq, because seq is less than tp->rcv_nxt ( tcp_sequence() ). Data from a send queue is sent only if there is enough space in a window, so when we restore unacked data, we need to expand a window to fit this data. This was in a first version of this patch: "tcp: extend window to fit all restored unacked data in a send queue" Then Alexey recommended me to restore window parameters instead of adjusted them according with data in a sent queue. This sounds resonable. rcv_wnd has to be restored, because it was reported to another side and the offered window is never shrunk. One of reasons why we need to restore snd_wnd was described above. Cc: Pavel Emelyanov <xemul@parallels.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> Cc: James Morris <jmorris@namei.org> Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org> Cc: Patrick McHardy <kaber@trash.net> Signed-off-by: Andrey Vagin <avagin@openvz.org> --- include/uapi/linux/tcp.h | 10 +++++++++ net/ipv4/tcp.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 67 insertions(+)