net/netfilter/nf_nat_proto_udp.c

   1 /* (C) 1999-2001 Paul `Rusty' Russell
   2  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/export.h>
  11 #include <linux/init.h>
  12 #include <linux/udp.h>
  13
  14 #include <linux/netfilter.h>
  15 #include <net/netfilter/nf_nat.h>
  16 #include <net/netfilter/nf_nat_core.h>
  17 #include <net/netfilter/nf_nat_l3proto.h>
  18 #include <net/netfilter/nf_nat_l4proto.h>
  19
  20 static u16 udp_port_rover;
  21
  22 static void
  23 udp_unique_tuple(const struct nf_nat_l3proto *l3proto,
  24                  struct nf_conntrack_tuple *tuple,
  25                  const struct nf_nat_range *range,
  26                  enum nf_nat_manip_type maniptype,
  27                  const struct nf_conn *ct)
  28 {
  29         nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
  30                                     &udp_port_rover);
  31 }
  32
  33 static void
  34 __udp_manip_pkt(struct sk_buff *skb,
  35                 const struct nf_nat_l3proto *l3proto,
  36                 unsigned int iphdroff, struct udphdr *hdr,
  37                 const struct nf_conntrack_tuple *tuple,
  38                 enum nf_nat_manip_type maniptype, bool do_csum)
  39 {
  40         __be16 *portptr, newport;
  41
  42         if (maniptype == NF_NAT_MANIP_SRC) {
  43                 /* Get rid of src port */
  44                 newport = tuple->src.u.udp.port;
  45                 portptr = &hdr->source;
  46         } else {
  47                 /* Get rid of dst port */
  48                 newport = tuple->dst.u.udp.port;
  49                 portptr = &hdr->dest;
  50         }
  51         if (do_csum) {
  52                 l3proto->csum_update(skb, iphdroff, &hdr->check,
  53                                      tuple, maniptype);
  54                 inet_proto_csum_replace2(&hdr->check, skb, *portptr, newport,
  55                                          false);
  56                 if (!hdr->check)
  57                         hdr->check = CSUM_MANGLED_0;
  58         }
  59         *portptr = newport;
  60 }
  61
  62 static bool udp_manip_pkt(struct sk_buff *skb,
  63                           const struct nf_nat_l3proto *l3proto,
  64                           unsigned int iphdroff, unsigned int hdroff,
  65                           const struct nf_conntrack_tuple *tuple,
  66                           enum nf_nat_manip_type maniptype)
  67 {
  68         struct udphdr *hdr;
  69         bool do_csum;
  70
  71         if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
  72                 return false;
  73
  74         hdr = (struct udphdr *)(skb->data + hdroff);
  75         do_csum = hdr->check || skb->ip_summed == CHECKSUM_PARTIAL;
  76
  77         __udp_manip_pkt(skb, l3proto, iphdroff, hdr, tuple, maniptype, do_csum);
  78         return true;
  79 }
  80
  81 #ifdef CONFIG_NF_NAT_PROTO_UDPLITE
  82 static u16 udplite_port_rover;
  83
  84 static bool udplite_manip_pkt(struct sk_buff *skb,
  85                               const struct nf_nat_l3proto *l3proto,
  86                               unsigned int iphdroff, unsigned int hdroff,
  87                               const struct nf_conntrack_tuple *tuple,
  88                               enum nf_nat_manip_type maniptype)
  89 {
  90         struct udphdr *hdr;
  91
  92         if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
  93                 return false;
  94
  95         hdr = (struct udphdr *)(skb->data + hdroff);
  96         __udp_manip_pkt(skb, l3proto, iphdroff, hdr, tuple, maniptype, true);
  97         return true;
  98 }
  99
 100 static void
 101 udplite_unique_tuple(const struct nf_nat_l3proto *l3proto,
 102                      struct nf_conntrack_tuple *tuple,
 103                      const struct nf_nat_range *range,
 104                      enum nf_nat_manip_type maniptype,
 105                      const struct nf_conn *ct)
 106 {
 107         nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
 108                                     &udplite_port_rover);
 109 }
 110
 111 const struct nf_nat_l4proto nf_nat_l4proto_udplite = {
 112         .l4proto                = IPPROTO_UDPLITE,
 113         .manip_pkt              = udplite_manip_pkt,
 114         .in_range               = nf_nat_l4proto_in_range,
 115         .unique_tuple           = udplite_unique_tuple,
 116 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 117         .nlattr_to_range        = nf_nat_l4proto_nlattr_to_range,
 118 #endif
 119 };
 120 #endif /* CONFIG_NF_NAT_PROTO_UDPLITE */
 121
 122 const struct nf_nat_l4proto nf_nat_l4proto_udp = {
 123         .l4proto                = IPPROTO_UDP,
 124         .manip_pkt              = udp_manip_pkt,
 125         .in_range               = nf_nat_l4proto_in_range,
 126         .unique_tuple           = udp_unique_tuple,
 127 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 128         .nlattr_to_range        = nf_nat_l4proto_nlattr_to_range,
 129 #endif
 130 };