target/linux/generic/patches-3.13/611-netfilter_match_bypass_default_table.patch

   1 --- a/net/ipv4/netfilter/ip_tables.c
   2 +++ b/net/ipv4/netfilter/ip_tables.c
   3 @@ -310,6 +310,33 @@ struct ipt_entry *ipt_next_entry(const s
   4         return (void *)entry + entry->next_offset;
   5  }
   6
   7 +static bool
   8 +ipt_handle_default_rule(struct ipt_entry *e, unsigned int *verdict)
   9 +{
  10 +       struct xt_entry_target *t;
  11 +       struct xt_standard_target *st;
  12 +
  13 +       if (e->target_offset != sizeof(struct ipt_entry))
  14 +               return false;
  15 +
  16 +       if (!(e->ip.flags & IPT_F_NO_DEF_MATCH))
  17 +               return false;
  18 +
  19 +       t = ipt_get_target(e);
  20 +       if (t->u.kernel.target->target)
  21 +               return false;
  22 +
  23 +       st = (struct xt_standard_target *) t;
  24 +       if (st->verdict == XT_RETURN)
  25 +               return false;
  26 +
  27 +       if (st->verdict >= 0)
  28 +               return false;
  29 +
  30 +       *verdict = (unsigned)(-st->verdict) - 1;
  31 +       return true;
  32 +}
  33 +
  34  /* Returns one of the generic firewall policies, like NF_ACCEPT. */
  35  unsigned int
  36  ipt_do_table(struct sk_buff *skb,
  37 @@ -334,19 +361,6 @@ ipt_do_table(struct sk_buff *skb,
  38         ip = ip_hdr(skb);
  39         indev = in ? in->name : nulldevname;
  40         outdev = out ? out->name : nulldevname;
  41 -       /* We handle fragments by dealing with the first fragment as
  42 -        * if it was a normal packet.  All other fragments are treated
  43 -        * normally, except that they will NEVER match rules that ask
  44 -        * things we don't know, ie. tcp syn flag or ports).  If the
  45 -        * rule is also a fragment-specific rule, non-fragments won't
  46 -        * match it. */
  47 -       acpar.fragoff = ntohs(ip->frag_off) & IP_OFFSET;
  48 -       acpar.thoff   = ip_hdrlen(skb);
  49 -       acpar.hotdrop = false;
  50 -       acpar.in      = in;
  51 -       acpar.out     = out;
  52 -       acpar.family  = NFPROTO_IPV4;
  53 -       acpar.hooknum = hook;
  54
  55         IP_NF_ASSERT(table->valid_hooks & (1 << hook));
  56         local_bh_disable();
  57 @@ -364,6 +378,26 @@ ipt_do_table(struct sk_buff *skb,
  58         origptr    = *stackptr;
  59
  60         e = get_entry(table_base, private->hook_entry[hook]);
  61 +       if (ipt_handle_default_rule(e, &verdict)) {
  62 +               ADD_COUNTER(e->counters, skb->len, 1);
  63 +               xt_write_recseq_end(addend);
  64 +               local_bh_enable();
  65 +               return verdict;
  66 +       }
  67 +
  68 +       /* We handle fragments by dealing with the first fragment as
  69 +        * if it was a normal packet.  All other fragments are treated
  70 +        * normally, except that they will NEVER match rules that ask
  71 +        * things we don't know, ie. tcp syn flag or ports).  If the
  72 +        * rule is also a fragment-specific rule, non-fragments won't
  73 +        * match it. */
  74 +       acpar.fragoff = ntohs(ip->frag_off) & IP_OFFSET;
  75 +       acpar.thoff   = ip_hdrlen(skb);
  76 +       acpar.hotdrop = false;
  77 +       acpar.in      = in;
  78 +       acpar.out     = out;
  79 +       acpar.family  = NFPROTO_IPV4;
  80 +       acpar.hooknum = hook;
  81
  82         pr_debug("Entering %s(hook %u); sp at %u (UF %p)\n",
  83                  table->name, hook, origptr,