LXR linux/net/ipv6/netfilter/nf_socket

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