net/ipv6/netfilter/nf_socket_ipv6.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2007-2008 BalaBit IT Ltd.
   4  * Author: Krisztian Kovacs
   5  */
   6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   7 #include <linux/module.h>
   8 #include <linux/skbuff.h>
   9 #include <net/tcp.h>
  10 #include <net/udp.h>
  11 #include <net/icmp.h>
  12 #include <net/sock.h>
  13 #include <net/inet_sock.h>
  14 #include <net/inet6_hashtables.h>
  15 #include <net/netfilter/nf_socket.h>
  16 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
  17 #include <net/netfilter/nf_conntrack.h>
  18 #endif
  19
  20 static int
  21 extract_icmp6_fields(const struct sk_buff *skb,
  22                      unsigned int outside_hdrlen,
  23                      int *protocol,
  24                      const struct in6_addr **raddr,
  25                      const struct in6_addr **laddr,
  26                      __be16 *rport,
  27                      __be16 *lport,
  28                      struct ipv6hdr *ipv6_var)
  29 {
  30         const struct ipv6hdr *inside_iph;
  31         struct icmp6hdr *icmph, _icmph;
  32         __be16 *ports, _ports[2];
  33         u8 inside_nexthdr;
  34         __be16 inside_fragoff;
  35         int inside_hdrlen;
  36
  37         icmph = skb_header_pointer(skb, outside_hdrlen,
  38                                    sizeof(_icmph), &_icmph);
  39         if (icmph == NULL)
  40                 return 1;
  41
  42         if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK)
  43                 return 1;
  44
  45         inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph),
  46                                         sizeof(*ipv6_var), ipv6_var);
  47         if (inside_iph == NULL)
  48                 return 1;
  49         inside_nexthdr = inside_iph->nexthdr;
  50
  51         inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) +
  52                                               sizeof(*ipv6_var),
  53                                          &inside_nexthdr, &inside_fragoff);
  54         if (inside_hdrlen < 0)
  55                 return 1; /* hjm: Packet has no/incomplete transport layer headers. */
  56
  57         if (inside_nexthdr != IPPROTO_TCP &&
  58             inside_nexthdr != IPPROTO_UDP)
  59                 return 1;
  60
  61         ports = skb_header_pointer(skb, inside_hdrlen,
  62                                    sizeof(_ports), &_ports);
  63         if (ports == NULL)
  64                 return 1;
  65
  66         /* the inside IP packet is the one quoted from our side, thus
  67          * its saddr is the local address */
  68         *protocol = inside_nexthdr;
  69         *laddr = &inside_iph->saddr;
  70         *lport = ports[0];
  71         *raddr = &inside_iph->daddr;
  72         *rport = ports[1];
  73
  74         return 0;
  75 }
  76
  77 static struct sock *
  78 nf_socket_get_sock_v6(struct net *net, struct sk_buff *skb, int doff,
  79                       const u8 protocol,
  80                       const struct in6_addr *saddr, const struct in6_addr *daddr,
  81                       const __be16 sport, const __be16 dport,
  82                       const struct net_device *in)
  83 {
  84         switch (protocol) {
  85         case IPPROTO_TCP:
  86                 return inet6_lookup(net, &tcp_hashinfo, skb, doff,
  87                                     saddr, sport, daddr, dport,
  88                                     in->ifindex);
  89         case IPPROTO_UDP:
  90                 return udp6_lib_lookup(net, saddr, sport, daddr, dport,
  91                                        in->ifindex);
  92         }
  93
  94         return NULL;
  95 }
  96
  97 struct sock *nf_sk_lookup_slow_v6(struct net *net, const struct sk_buff *skb,
  98                                   const struct net_device *indev)
  99 {
 100         __be16 dport, sport;
 101         const struct in6_addr *daddr = NULL, *saddr = NULL;
 102         struct ipv6hdr *iph = ipv6_hdr(skb), ipv6_var;
 103         struct sk_buff *data_skb = NULL;
 104         int doff = 0;
 105         int thoff = 0, tproto;
 106
 107         tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
 108         if (tproto < 0) {
 109                 pr_debug("unable to find transport header in IPv6 packet, dropping\n");
 110                 return NULL;
 111         }
 112
 113         if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) {
 114                 struct tcphdr _hdr;
 115                 struct udphdr *hp;
 116
 117                 hp = skb_header_pointer(skb, thoff, tproto == IPPROTO_UDP ?
 118                                         sizeof(*hp) : sizeof(_hdr), &_hdr);
 119                 if (hp == NULL)
 120                         return NULL;
 121
 122                 saddr = &iph->saddr;
 123                 sport = hp->source;
 124                 daddr = &iph->daddr;
 125                 dport = hp->dest;
 126                 data_skb = (struct sk_buff *)skb;
 127                 doff = tproto == IPPROTO_TCP ?
 128                         thoff + __tcp_hdrlen((struct tcphdr *)hp) :
 129                         thoff + sizeof(*hp);
 130
 131         } else if (tproto == IPPROTO_ICMPV6) {
 132                 if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,
 133                                          &sport, &dport, &ipv6_var))
 134                         return NULL;
 135         } else {
 136                 return NULL;
 137         }
 138
 139         return nf_socket_get_sock_v6(net, data_skb, doff, tproto, saddr, daddr,
 140                                      sport, dport, indev);
 141 }
 142 EXPORT_SYMBOL_GPL(nf_sk_lookup_slow_v6);
 143
 144 MODULE_LICENSE("GPL");
 145 MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
 146 MODULE_DESCRIPTION("Netfilter IPv6 socket lookup infrastructure");