target/linux/generic/pending-4.4/610-netfilter_match_bypass_default_checks.patch

   1 --- a/include/uapi/linux/netfilter_ipv4/ip_tables.h
   2 +++ b/include/uapi/linux/netfilter_ipv4/ip_tables.h
   3 @@ -87,6 +87,7 @@ struct ipt_ip {
   4  #define IPT_F_FRAG             0x01    /* Set if rule is a fragment rule */
   5  #define IPT_F_GOTO             0x02    /* Set if jump is a goto */
   6  #define IPT_F_MASK             0x03    /* All possible flag bits mask. */
   7 +#define IPT_F_NO_DEF_MATCH     0x80    /* Internal: no default match rules present */
   8
   9  /* Values for "inv" field in struct ipt_ip. */
  10  #define IPT_INV_VIA_IN         0x01    /* Invert the sense of IN IFACE. */
  11 --- a/net/ipv4/netfilter/ip_tables.c
  12 +++ b/net/ipv4/netfilter/ip_tables.c
  13 @@ -82,6 +82,9 @@ ip_packet_match(const struct iphdr *ip,
  14
  15  #define FWINV(bool, invflg) ((bool) ^ !!(ipinfo->invflags & (invflg)))
  16
  17 +       if (ipinfo->flags & IPT_F_NO_DEF_MATCH)
  18 +               return true;
  19 +
  20         if (FWINV((ip->saddr&ipinfo->smsk.s_addr) != ipinfo->src.s_addr,
  21                   IPT_INV_SRCIP) ||
  22             FWINV((ip->daddr&ipinfo->dmsk.s_addr) != ipinfo->dst.s_addr,
  23 @@ -135,6 +138,29 @@ ip_packet_match(const struct iphdr *ip,
  24         return true;
  25  }
  26
  27 +static void
  28 +ip_checkdefault(struct ipt_ip *ip)
  29 +{
  30 +       static const char iface_mask[IFNAMSIZ] = {};
  31 +
  32 +       if (ip->invflags || ip->flags & IPT_F_FRAG)
  33 +               return;
  34 +
  35 +       if (memcmp(ip->iniface_mask, iface_mask, IFNAMSIZ) != 0)
  36 +               return;
  37 +
  38 +       if (memcmp(ip->outiface_mask, iface_mask, IFNAMSIZ) != 0)
  39 +               return;
  40 +
  41 +       if (ip->smsk.s_addr || ip->dmsk.s_addr)
  42 +               return;
  43 +
  44 +       if (ip->proto)
  45 +               return;
  46 +
  47 +       ip->flags |= IPT_F_NO_DEF_MATCH;
  48 +}
  49 +
  50  static bool
  51  ip_checkentry(const struct ipt_ip *ip)
  52  {
  53 @@ -664,6 +690,8 @@ find_check_entry(struct ipt_entry *e, st
  54         struct xt_mtchk_param mtpar;
  55         struct xt_entry_match *ematch;
  56
  57 +       ip_checkdefault(&e->ip);
  58 +
  59         e->counters.pcnt = xt_percpu_counter_alloc();
  60         if (IS_ERR_VALUE(e->counters.pcnt))
  61                 return -ENOMEM;
  62 @@ -948,6 +976,7 @@ copy_entries_to_user(unsigned int total_
  63         const struct xt_table_info *private = table->private;
  64         int ret = 0;
  65         const void *loc_cpu_entry;
  66 +       u8 flags;
  67
  68         counters = alloc_counters(table);
  69         if (IS_ERR(counters))
  70 @@ -974,6 +1003,14 @@ copy_entries_to_user(unsigned int total_
  71                         ret = -EFAULT;
  72                         goto free_counters;
  73                 }
  74 +
  75 +               flags = e->ip.flags & IPT_F_MASK;
  76 +               if (copy_to_user(userptr + off
  77 +                                + offsetof(struct ipt_entry, ip.flags),
  78 +                                &flags, sizeof(flags)) != 0) {
  79 +                       ret = -EFAULT;
  80 +                       goto free_counters;
  81 +               }
  82
  83                 for (i = sizeof(struct ipt_entry);
  84                      i < e->target_offset;