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
21 static int
22 extract_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
78 static struct sock *
79 nf_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
98 struct 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 }
145 EXPORT_SYMBOL_GPL(nf_sk_lookup_slow_v6);
146
147 MODULE_LICENSE("GPL");
148 MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
149 MODULE_DESCRIPTION("Netfilter IPv6 socket lookup infrastructure");
150
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