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
 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, skb, doff, saddr, sport, daddr, dport,
 87				    in->ifindex);
 88	case IPPROTO_UDP:
 89		return udp6_lib_lookup(net, saddr, sport, daddr, dport,
 90				       in->ifindex);
 91	}
 92
 93	return NULL;
 94}
 95
 96struct sock *nf_sk_lookup_slow_v6(struct net *net, const struct sk_buff *skb,
 97				  const struct net_device *indev)
 98{
 99	__be16 dport, sport;
100	const struct in6_addr *daddr = NULL, *saddr = NULL;
101	struct ipv6hdr *iph = ipv6_hdr(skb), ipv6_var;
102	struct sk_buff *data_skb = NULL;
103	int doff = 0;
104	int thoff = 0, tproto;
105#if IS_ENABLED(CONFIG_NF_CONNTRACK)
106	enum ip_conntrack_info ctinfo;
107	struct nf_conn const *ct;
108#endif
109
110	tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
111	if (tproto < 0) {
112		pr_debug("unable to find transport header in IPv6 packet, dropping\n");
113		return NULL;
114	}
115
116	if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) {
117		struct tcphdr _hdr;
118		struct udphdr *hp;
119
120		hp = skb_header_pointer(skb, thoff, tproto == IPPROTO_UDP ?
121					sizeof(*hp) : sizeof(_hdr), &_hdr);
122		if (hp == NULL)
123			return NULL;
124
125		saddr = &iph->saddr;
126		sport = hp->source;
127		daddr = &iph->daddr;
128		dport = hp->dest;
129		data_skb = (struct sk_buff *)skb;
130		doff = tproto == IPPROTO_TCP ?
131			thoff + __tcp_hdrlen((struct tcphdr *)hp) :
132			thoff + sizeof(*hp);
133
134	} else if (tproto == IPPROTO_ICMPV6) {
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#if IS_ENABLED(CONFIG_NF_CONNTRACK)
143	/* Do the lookup with the original socket address in
144	 * case this is a reply packet of an established
145	 * SNAT-ted connection.
146	 */
147	ct = nf_ct_get(skb, &ctinfo);
148	if (ct &&
149	    ((tproto != IPPROTO_ICMPV6 &&
150	      ctinfo == IP_CT_ESTABLISHED_REPLY) ||
151	     (tproto == IPPROTO_ICMPV6 &&
152	      ctinfo == IP_CT_RELATED_REPLY)) &&
153	    (ct->status & IPS_SRC_NAT_DONE)) {
154		daddr = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.in6;
155		dport = (tproto == IPPROTO_TCP) ?
156			ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
157			ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
158	}
159#endif
160
161	return nf_socket_get_sock_v6(net, data_skb, doff, tproto, saddr, daddr,
162				     sport, dport, indev);
163}
164EXPORT_SYMBOL_GPL(nf_sk_lookup_slow_v6);
165
166MODULE_LICENSE("GPL");
167MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
168MODULE_DESCRIPTION("Netfilter IPv6 socket lookup infrastructure");