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/netfilter/nf_socket.h>
15 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
16 #include <net/netfilter/nf_conntrack.h>
17 #endif
18
19 static int
extract_icmp4_fields(const struct sk_buff * skb,u8 * protocol,__be32 * raddr,__be32 * laddr,__be16 * rport,__be16 * lport)20 extract_icmp4_fields(const struct sk_buff *skb, u8 *protocol,
21 __be32 *raddr, __be32 *laddr,
22 __be16 *rport, __be16 *lport)
23 {
24 unsigned int outside_hdrlen = ip_hdrlen(skb);
25 struct iphdr *inside_iph, _inside_iph;
26 struct icmphdr *icmph, _icmph;
27 __be16 *ports, _ports[2];
28
29 icmph = skb_header_pointer(skb, outside_hdrlen,
30 sizeof(_icmph), &_icmph);
31 if (icmph == NULL)
32 return 1;
33
34 switch (icmph->type) {
35 case ICMP_DEST_UNREACH:
36 case ICMP_SOURCE_QUENCH:
37 case ICMP_REDIRECT:
38 case ICMP_TIME_EXCEEDED:
39 case ICMP_PARAMETERPROB:
40 break;
41 default:
42 return 1;
43 }
44
45 inside_iph = skb_header_pointer(skb, outside_hdrlen +
46 sizeof(struct icmphdr),
47 sizeof(_inside_iph), &_inside_iph);
48 if (inside_iph == NULL)
49 return 1;
50
51 if (inside_iph->protocol != IPPROTO_TCP &&
52 inside_iph->protocol != IPPROTO_UDP)
53 return 1;
54
55 ports = skb_header_pointer(skb, outside_hdrlen +
56 sizeof(struct icmphdr) +
57 (inside_iph->ihl << 2),
58 sizeof(_ports), &_ports);
59 if (ports == NULL)
60 return 1;
61
62 /* the inside IP packet is the one quoted from our side, thus
63 * its saddr is the local address */
64 *protocol = inside_iph->protocol;
65 *laddr = inside_iph->saddr;
66 *lport = ports[0];
67 *raddr = inside_iph->daddr;
68 *rport = ports[1];
69
70 return 0;
71 }
72
73 static struct sock *
nf_socket_get_sock_v4(struct net * net,struct sk_buff * skb,const int doff,const u8 protocol,const __be32 saddr,const __be32 daddr,const __be16 sport,const __be16 dport,const struct net_device * in)74 nf_socket_get_sock_v4(struct net *net, struct sk_buff *skb, const int doff,
75 const u8 protocol,
76 const __be32 saddr, const __be32 daddr,
77 const __be16 sport, const __be16 dport,
78 const struct net_device *in)
79 {
80 switch (protocol) {
81 case IPPROTO_TCP:
82 return inet_lookup(net, &tcp_hashinfo, skb, doff,
83 saddr, sport, daddr, dport,
84 in->ifindex);
85 case IPPROTO_UDP:
86 return udp4_lib_lookup(net, saddr, sport, daddr, dport,
87 in->ifindex);
88 }
89 return NULL;
90 }
91
nf_sk_lookup_slow_v4(struct net * net,const struct sk_buff * skb,const struct net_device * indev)92 struct sock *nf_sk_lookup_slow_v4(struct net *net, const struct sk_buff *skb,
93 const struct net_device *indev)
94 {
95 __be32 uninitialized_var(daddr), uninitialized_var(saddr);
96 __be16 uninitialized_var(dport), uninitialized_var(sport);
97 const struct iphdr *iph = ip_hdr(skb);
98 struct sk_buff *data_skb = NULL;
99 u8 uninitialized_var(protocol);
100 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
101 enum ip_conntrack_info ctinfo;
102 struct nf_conn const *ct;
103 #endif
104 int doff = 0;
105
106 if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) {
107 struct tcphdr _hdr;
108 struct udphdr *hp;
109
110 hp = skb_header_pointer(skb, ip_hdrlen(skb),
111 iph->protocol == IPPROTO_UDP ?
112 sizeof(*hp) : sizeof(_hdr), &_hdr);
113 if (hp == NULL)
114 return NULL;
115
116 protocol = iph->protocol;
117 saddr = iph->saddr;
118 sport = hp->source;
119 daddr = iph->daddr;
120 dport = hp->dest;
121 data_skb = (struct sk_buff *)skb;
122 doff = iph->protocol == IPPROTO_TCP ?
123 ip_hdrlen(skb) + __tcp_hdrlen((struct tcphdr *)hp) :
124 ip_hdrlen(skb) + sizeof(*hp);
125
126 } else if (iph->protocol == IPPROTO_ICMP) {
127 if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr,
128 &sport, &dport))
129 return NULL;
130 } else {
131 return NULL;
132 }
133
134 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
135 /* Do the lookup with the original socket address in
136 * case this is a reply packet of an established
137 * SNAT-ted connection.
138 */
139 ct = nf_ct_get(skb, &ctinfo);
140 if (ct &&
141 ((iph->protocol != IPPROTO_ICMP &&
142 ctinfo == IP_CT_ESTABLISHED_REPLY) ||
143 (iph->protocol == IPPROTO_ICMP &&
144 ctinfo == IP_CT_RELATED_REPLY)) &&
145 (ct->status & IPS_SRC_NAT_DONE)) {
146
147 daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
148 dport = (iph->protocol == IPPROTO_TCP) ?
149 ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
150 ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
151 }
152 #endif
153
154 return nf_socket_get_sock_v4(net, data_skb, doff, protocol, saddr,
155 daddr, sport, dport, indev);
156 }
157 EXPORT_SYMBOL_GPL(nf_sk_lookup_slow_v4);
158
159 MODULE_LICENSE("GPL");
160 MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
161 MODULE_DESCRIPTION("Netfilter IPv4 socket lookup infrastructure");
162