target/linux/generic/patches-3.19/611-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 @@ -331,9 +358,33 @@ ipt_do_table(struct sk_buff *skb,
  38         unsigned int addend;
  39
  40         /* Initialization */
  41 +       IP_NF_ASSERT(table->valid_hooks & (1 << hook));
  42 +       local_bh_disable();
  43 +       private = table->private;
  44 +       cpu        = smp_processor_id();
  45 +       /*
  46 +        * Ensure we load private-> members after we've fetched the base
  47 +        * pointer.
  48 +        */
  49 +       smp_read_barrier_depends();
  50 +       table_base = private->entries[cpu];
  51 +
  52 +       e = get_entry(table_base, private->hook_entry[hook]);
  53 +       if (ipt_handle_default_rule(e, &verdict)) {
  54 +               ADD_COUNTER(e->counters, skb->len, 1);
  55 +               local_bh_enable();
  56 +               return verdict;
  57 +       }
  58 +
  59         ip = ip_hdr(skb);
  60         indev = in ? in->name : nulldevname;
  61         outdev = out ? out->name : nulldevname;
  62 +
  63 +       addend = xt_write_recseq_begin();
  64 +       jumpstack  = (struct ipt_entry **)private->jumpstack[cpu];
  65 +       stackptr   = per_cpu_ptr(private->stackptr, cpu);
  66 +       origptr    = *stackptr;
  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 @@ -348,23 +399,6 @@ ipt_do_table(struct sk_buff *skb,
  72         acpar.family  = NFPROTO_IPV4;
  73         acpar.hooknum = hook;
  74
  75 -       IP_NF_ASSERT(table->valid_hooks & (1 << hook));
  76 -       local_bh_disable();
  77 -       addend = xt_write_recseq_begin();
  78 -       private = table->private;
  79 -       cpu        = smp_processor_id();
  80 -       /*
  81 -        * Ensure we load private-> members after we've fetched the base
  82 -        * pointer.
  83 -        */
  84 -       smp_read_barrier_depends();
  85 -       table_base = private->entries[cpu];
  86 -       jumpstack  = (struct ipt_entry **)private->jumpstack[cpu];
  87 -       stackptr   = per_cpu_ptr(private->stackptr, cpu);
  88 -       origptr    = *stackptr;
  89 -
  90 -       e = get_entry(table_base, private->hook_entry[hook]);
  91 -
  92         pr_debug("Entering %s(hook %u); sp at %u (UF %p)\n",
  93                  table->name, hook, origptr,
  94                  get_entry(table_base, private->underflow[hook]));