net/ipv6/netfilter/nf_socket_ipv6.c

   1 /*
   2  * Copyright (C) 2007-2008 BalaBit IT Ltd.
   3  * Author: Krisztian Kovacs
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  */
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11 #include <linux/module.h>
  12 #include <linux/skbuff.h>
  13 #include <net/tcp.h>
  14 #include <net/udp.h>
  15 #include <net/icmp.h>
  16 #include <net/sock.h>
  17 #include <net/inet_sock.h>
  18 #include <net/inet6_hashtables.h>
  19 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
  20 #include <net/netfilter/nf_socket.h>
  21 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
  22 #include <net/netfilter/nf_conntrack.h>
  23 #endif
  24
  25 static int
  26 extract_icmp6_fields(const struct sk_buff *skb,
  27                      unsigned int outside_hdrlen,
  28                      int *protocol,
  29                      const struct in6_addr **raddr,
  30                      const struct in6_addr **laddr,
  31                      __be16 *rport,
  32                      __be16 *lport,
  33                      struct ipv6hdr *ipv6_var)
  34 {
  35         const struct ipv6hdr *inside_iph;
  36         struct icmp6hdr *icmph, _icmph;
  37         __be16 *ports, _ports[2];
  38         u8 inside_nexthdr;
  39         __be16 inside_fragoff;
  40         int inside_hdrlen;
  41
  42         icmph = skb_header_pointer(skb, outside_hdrlen,
  43                                    sizeof(_icmph), &_icmph);
  44         if (icmph == NULL)
  45                 return 1;
  46
  47         if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK)
  48                 return 1;
  49
  50         inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph),
  51                                         sizeof(*ipv6_var), ipv6_var);
  52         if (inside_iph == NULL)
  53                 return 1;
  54         inside_nexthdr = inside_iph->nexthdr;
  55
  56         inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) +
  57                                               sizeof(*ipv6_var),
  58                                          &inside_nexthdr, &inside_fragoff);
  59         if (inside_hdrlen < 0)
  60                 return 1; /* hjm: Packet has no/incomplete transport layer headers. */
  61
  62         if (inside_nexthdr != IPPROTO_TCP &&
  63             inside_nexthdr != IPPROTO_UDP)
  64                 return 1;
  65
  66         ports = skb_header_pointer(skb, inside_hdrlen,
  67                                    sizeof(_ports), &_ports);
  68         if (ports == NULL)
  69                 return 1;
  70
  71         /* the inside IP packet is the one quoted from our side, thus
  72          * its saddr is the local address */
  73         *protocol = inside_nexthdr;
  74         *laddr = &inside_iph->saddr;
  75         *lport = ports[0];
  76         *raddr = &inside_iph->daddr;
  77         *rport = ports[1];
  78
  79         return 0;
  80 }
  81
  82 static struct sock *
  83 nf_socket_get_sock_v6(struct net *net, struct sk_buff *skb, int doff,
  84                       const u8 protocol,
  85                       const struct in6_addr *saddr, const struct in6_addr *daddr,
  86                       const __be16 sport, const __be16 dport,
  87                       const struct net_device *in)
  88 {
  89         switch (protocol) {
  90         case IPPROTO_TCP:
  91                 return inet6_lookup(net, &tcp_hashinfo, skb, doff,
  92                                     saddr, sport, daddr, dport,
  93                                     in->ifindex);
  94         case IPPROTO_UDP:
  95                 return udp6_lib_lookup(net, saddr, sport, daddr, dport,
  96                                        in->ifindex);
  97         }
  98
  99         return NULL;
 100 }
 101
 102 struct sock *nf_sk_lookup_slow_v6(struct net *net, const struct sk_buff *skb,
 103                                   const struct net_device *indev)
 104 {
 105         __be16 uninitialized_var(dport), uninitialized_var(sport);
 106         const struct in6_addr *daddr = NULL, *saddr = NULL;
 107         struct ipv6hdr *iph = ipv6_hdr(skb), ipv6_var;
 108         struct sk_buff *data_skb = NULL;
 109         int doff = 0;
 110         int thoff = 0, tproto;
 111
 112         tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
 113         if (tproto < 0) {
 114                 pr_debug("unable to find transport header in IPv6 packet, dropping\n");
 115                 return NULL;
 116         }
 117
 118         if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) {
 119                 struct tcphdr _hdr;
 120                 struct udphdr *hp;
 121
 122                 hp = skb_header_pointer(skb, thoff, tproto == IPPROTO_UDP ?
 123                                         sizeof(*hp) : sizeof(_hdr), &_hdr);
 124                 if (hp == NULL)
 125                         return NULL;
 126
 127                 saddr = &iph->saddr;
 128                 sport = hp->source;
 129                 daddr = &iph->daddr;
 130                 dport = hp->dest;
 131                 data_skb = (struct sk_buff *)skb;
 132                 doff = tproto == IPPROTO_TCP ?
 133                         thoff + __tcp_hdrlen((struct tcphdr *)hp) :
 134                         thoff + sizeof(*hp);
 135
 136         } else if (tproto == IPPROTO_ICMPV6) {
 137                 if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,
 138                                          &sport, &dport, &ipv6_var))
 139                         return NULL;
 140         } else {
 141                 return NULL;
 142         }
 143
 144         return nf_socket_get_sock_v6(net, data_skb, doff, tproto, saddr, daddr,
 145                                      sport, dport, indev);
 146 }
 147 EXPORT_SYMBOL_GPL(nf_sk_lookup_slow_v6);
 148
 149 MODULE_LICENSE("GPL");
 150 MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
 151 MODULE_DESCRIPTION("Netfilter IPv6 socket lookup infrastructure");