release/src/linux/linux/net/ipv4/netfilter/ip_nat_proto_icmp.c

   1 #include <linux/types.h>
   2 #include <linux/init.h>
   3 #include <linux/netfilter.h>
   4 #include <linux/ip.h>
   5 #include <linux/icmp.h>
   6 #include <linux/if.h>
   7
   8 #include <linux/netfilter_ipv4/ip_nat.h>
   9 #include <linux/netfilter_ipv4/ip_nat_rule.h>
  10 #include <linux/netfilter_ipv4/ip_nat_protocol.h>
  11
  12 static int
  13 icmp_in_range(const struct ip_conntrack_tuple *tuple,
  14               enum ip_nat_manip_type maniptype,
  15               const union ip_conntrack_manip_proto *min,
  16               const union ip_conntrack_manip_proto *max)
  17 {
  18         return (tuple->src.u.icmp.id >= min->icmp.id
  19                 && tuple->src.u.icmp.id <= max->icmp.id);
  20 }
  21
  22 static int
  23 icmp_unique_tuple(struct ip_conntrack_tuple *tuple,
  24                   const struct ip_nat_range *range,
  25                   enum ip_nat_manip_type maniptype,
  26                   const struct ip_conntrack *conntrack)
  27 {
  28         static u_int16_t id = 0;
  29         unsigned int range_size
  30                 = (unsigned int)range->max.icmp.id - range->min.icmp.id + 1;
  31         unsigned int i;
  32
  33         /* If no range specified... */
  34         if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED))
  35                 range_size = 0xFFFF;
  36
  37         for (i = 0; i < range_size; i++, id++) {
  38                 tuple->src.u.icmp.id = range->min.icmp.id + (id % range_size);
  39                 if (!ip_nat_used_tuple(tuple, conntrack))
  40                         return 1;
  41         }
  42         return 0;
  43 }
  44
  45 static void
  46 icmp_manip_pkt(struct iphdr *iph, size_t len,
  47                const struct ip_conntrack_manip *manip,
  48                enum ip_nat_manip_type maniptype)
  49 {
  50         struct icmphdr *hdr = (struct icmphdr *)((u_int32_t *)iph + iph->ihl);
  51
  52         hdr->checksum = ip_nat_cheat_check(hdr->un.echo.id ^ 0xFFFF,
  53                                            manip->u.icmp.id,
  54                                            hdr->checksum);
  55         hdr->un.echo.id = manip->u.icmp.id;
  56 }
  57
  58 static unsigned int
  59 icmp_print(char *buffer,
  60            const struct ip_conntrack_tuple *match,
  61            const struct ip_conntrack_tuple *mask)
  62 {
  63         unsigned int len = 0;
  64
  65         if (mask->src.u.icmp.id)
  66                 len += sprintf(buffer + len, "id=%u ",
  67                                ntohs(match->src.u.icmp.id));
  68
  69         if (mask->dst.u.icmp.type)
  70                 len += sprintf(buffer + len, "type=%u ",
  71                                ntohs(match->dst.u.icmp.type));
  72
  73         if (mask->dst.u.icmp.code)
  74                 len += sprintf(buffer + len, "code=%u ",
  75                                ntohs(match->dst.u.icmp.code));
  76
  77         return len;
  78 }
  79
  80 static unsigned int
  81 icmp_print_range(char *buffer, const struct ip_nat_range *range)
  82 {
  83         if (range->min.icmp.id != 0 || range->max.icmp.id != 0xFFFF)
  84                 return sprintf(buffer, "id %u-%u ",
  85                                ntohs(range->min.icmp.id),
  86                                ntohs(range->max.icmp.id));
  87         else return 0;
  88 }
  89
  90 struct ip_nat_protocol ip_nat_protocol_icmp
  91 = { { NULL, NULL }, "ICMP", IPPROTO_ICMP,
  92     icmp_manip_pkt,
  93     icmp_in_range,
  94     icmp_unique_tuple,
  95     icmp_print,
  96     icmp_print_range
  97 };