target/linux/generic/patches-4.4/613-netfilter_optional_tcp_window_check.patch

   1 --- a/net/netfilter/nf_conntrack_proto_tcp.c
   2 +++ b/net/netfilter/nf_conntrack_proto_tcp.c
   3 @@ -33,6 +33,9 @@
   4  #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
   5  #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
   6
   7 +/* Do not check the TCP window for incoming packets  */
   8 +static int nf_ct_tcp_no_window_check __read_mostly = 1;
   9 +
  10  /* "Be conservative in what you do,
  11      be liberal in what you accept from others."
  12      If it's non-zero, we mark only out of window RST segments as INVALID. */
  13 @@ -515,6 +518,9 @@ static bool tcp_in_window(const struct n
  14         s32 receiver_offset;
  15         bool res, in_recv_win;
  16
  17 +       if (nf_ct_tcp_no_window_check)
  18 +               return true;
  19 +
  20         /*
  21          * Get the required data from the packet.
  22          */
  23 @@ -1481,6 +1487,13 @@ static struct ctl_table tcp_sysctl_table
  24                 .mode           = 0644,
  25                 .proc_handler   = proc_dointvec,
  26         },
  27 +       {
  28 +               .procname       = "nf_conntrack_tcp_no_window_check",
  29 +               .data           = &nf_ct_tcp_no_window_check,
  30 +               .maxlen         = sizeof(unsigned int),
  31 +               .mode           = 0644,
  32 +               .proc_handler   = proc_dointvec,
  33 +       },
  34         { }
  35  };
  36