target/linux/generic/patches-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 @@ -569,7 +595,7 @@ static void cleanup_match(struct xt_entr
  54  }
  55
  56  static int
  57 -check_entry(const struct ipt_entry *e, const char *name)
  58 +check_entry(struct ipt_entry *e, const char *name)
  59  {
  60         const struct xt_entry_target *t;
  61
  62 @@ -578,6 +604,8 @@ check_entry(const struct ipt_entry *e, c
  63                 return -EINVAL;
  64         }
  65
  66 +       ip_checkdefault(&e->ip);
  67 +
  68         if (e->target_offset + sizeof(struct xt_entry_target) >
  69             e->next_offset)
  70                 return -EINVAL;
  71 @@ -944,6 +972,7 @@ copy_entries_to_user(unsigned int total_
  72         const struct xt_table_info *private = table->private;
  73         int ret = 0;
  74         const void *loc_cpu_entry;
  75 +       u8 flags;
  76
  77         counters = alloc_counters(table);
  78         if (IS_ERR(counters))
  79 @@ -970,6 +999,14 @@ copy_entries_to_user(unsigned int total_
  80                         ret = -EFAULT;
  81                         goto free_counters;
  82                 }
  83 +
  84 +               flags = e->ip.flags & IPT_F_MASK;
  85 +               if (copy_to_user(userptr + off
  86 +                                + offsetof(struct ipt_entry, ip.flags),
  87 +                                &flags, sizeof(flags)) != 0) {
  88 +                       ret = -EFAULT;
  89 +                       goto free_counters;
  90 +               }
  91
  92                 for (i = sizeof(struct ipt_entry);
  93                      i < e->target_offset;