LXR linux/net/ipv6/netfilter/nf_socket

   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
  25static int
  26extract_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
  82static struct sock *
  83nf_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
 102struct 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);
 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                struct ipv6hdr ipv6_var;
 138
 139                if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,
 140                                         &sport, &dport, &ipv6_var))
 141                        return NULL;
 142        } else {
 143                return NULL;
 144        }
 145
 146        return nf_socket_get_sock_v6(net, data_skb, doff, tproto, saddr, daddr,
 147                                     sport, dport, indev);
 148}
 149EXPORT_SYMBOL_GPL(nf_sk_lookup_slow_v6);
 150
 151MODULE_LICENSE("GPL");
 152MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
 153MODULE_DESCRIPTION("Netfilter IPv6 socket lookup infrastructure");
 154