linux/net/ipv6/netfilter/nf_socket_ipv6.c
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   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
  20static int
  21extract_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
  77static struct sock *
  78nf_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
  97struct 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);
 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                struct ipv6hdr ipv6_var;
 133
 134                if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,
 135                                         &sport, &dport, &ipv6_var))
 136                        return NULL;
 137        } else {
 138                return NULL;
 139        }
 140
 141        return nf_socket_get_sock_v6(net, data_skb, doff, tproto, saddr, daddr,
 142                                     sport, dport, indev);
 143}
 144EXPORT_SYMBOL_GPL(nf_sk_lookup_slow_v6);
 145
 146MODULE_LICENSE("GPL");
 147MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
 148MODULE_DESCRIPTION("Netfilter IPv6 socket lookup infrastructure");
 149