1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * iptables module to match inet_addr_type() of an ip.
4 *
5 * Copyright (c) 2004 Patrick McHardy <kaber@trash.net>
6 * (C) 2007 Laszlo Attila Toth <panther@balabit.hu>
7 */
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/skbuff.h>
12#include <linux/netdevice.h>
13#include <linux/ip.h>
14#include <net/route.h>
15
16#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
17#include <net/ipv6.h>
18#include <net/ip6_route.h>
19#include <net/ip6_fib.h>
20#endif
21
22#include <linux/netfilter_ipv6.h>
23#include <linux/netfilter/xt_addrtype.h>
24#include <linux/netfilter/x_tables.h>
25
26MODULE_LICENSE("GPL");
27MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
28MODULE_DESCRIPTION("Xtables: address type match");
29MODULE_ALIAS("ipt_addrtype");
30MODULE_ALIAS("ip6t_addrtype");
31
32#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
33static u32 match_lookup_rt6(struct net *net, const struct net_device *dev,
34 const struct in6_addr *addr, u16 mask)
35{
36 struct flowi6 flow;
37 struct rt6_info *rt;
38 u32 ret = 0;
39 int route_err;
40
41 memset(&flow, 0, sizeof(flow));
42 flow.daddr = *addr;
43 if (dev)
44 flow.flowi6_oif = dev->ifindex;
45
46 if (dev && (mask & XT_ADDRTYPE_LOCAL)) {
47 if (nf_ipv6_chk_addr(net, addr, dev, strict: true))
48 ret = XT_ADDRTYPE_LOCAL;
49 }
50
51 route_err = nf_ip6_route(net, dst: (struct dst_entry **)&rt,
52 fl: flowi6_to_flowi(fl6: &flow), strict: false);
53 if (route_err)
54 return XT_ADDRTYPE_UNREACHABLE;
55
56 if (rt->rt6i_flags & RTF_REJECT)
57 ret = XT_ADDRTYPE_UNREACHABLE;
58
59 if (dev == NULL && rt->rt6i_flags & RTF_LOCAL)
60 ret |= XT_ADDRTYPE_LOCAL;
61 if (ipv6_anycast_destination(dst: (struct dst_entry *)rt, daddr: addr))
62 ret |= XT_ADDRTYPE_ANYCAST;
63
64 dst_release(dst: &rt->dst);
65 return ret;
66}
67
68static bool match_type6(struct net *net, const struct net_device *dev,
69 const struct in6_addr *addr, u16 mask)
70{
71 int addr_type = ipv6_addr_type(addr);
72
73 if ((mask & XT_ADDRTYPE_MULTICAST) &&
74 !(addr_type & IPV6_ADDR_MULTICAST))
75 return false;
76 if ((mask & XT_ADDRTYPE_UNICAST) && !(addr_type & IPV6_ADDR_UNICAST))
77 return false;
78 if ((mask & XT_ADDRTYPE_UNSPEC) && addr_type != IPV6_ADDR_ANY)
79 return false;
80
81 if ((XT_ADDRTYPE_LOCAL | XT_ADDRTYPE_ANYCAST |
82 XT_ADDRTYPE_UNREACHABLE) & mask)
83 return !!(mask & match_lookup_rt6(net, dev, addr, mask));
84 return true;
85}
86
87static bool
88addrtype_mt6(struct net *net, const struct net_device *dev,
89 const struct sk_buff *skb, const struct xt_addrtype_info_v1 *info)
90{
91 const struct ipv6hdr *iph = ipv6_hdr(skb);
92 bool ret = true;
93
94 if (info->source)
95 ret &= match_type6(net, dev, addr: &iph->saddr, mask: info->source) ^
96 (info->flags & XT_ADDRTYPE_INVERT_SOURCE);
97 if (ret && info->dest)
98 ret &= match_type6(net, dev, addr: &iph->daddr, mask: info->dest) ^
99 !!(info->flags & XT_ADDRTYPE_INVERT_DEST);
100 return ret;
101}
102#endif
103
104static inline bool match_type(struct net *net, const struct net_device *dev,
105 __be32 addr, u_int16_t mask)
106{
107 return !!(mask & (1 << inet_dev_addr_type(net, dev, addr)));
108}
109
110static bool
111addrtype_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
112{
113 struct net *net = xt_net(par);
114 const struct xt_addrtype_info *info = par->matchinfo;
115 const struct iphdr *iph = ip_hdr(skb);
116 bool ret = true;
117
118 if (info->source)
119 ret &= match_type(net, NULL, addr: iph->saddr, mask: info->source) ^
120 info->invert_source;
121 if (info->dest)
122 ret &= match_type(net, NULL, addr: iph->daddr, mask: info->dest) ^
123 info->invert_dest;
124
125 return ret;
126}
127
128static bool
129addrtype_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
130{
131 struct net *net = xt_net(par);
132 const struct xt_addrtype_info_v1 *info = par->matchinfo;
133 const struct iphdr *iph;
134 const struct net_device *dev = NULL;
135 bool ret = true;
136
137 if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN)
138 dev = xt_in(par);
139 else if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT)
140 dev = xt_out(par);
141
142#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
143 if (xt_family(par) == NFPROTO_IPV6)
144 return addrtype_mt6(net, dev, skb, info);
145#endif
146 iph = ip_hdr(skb);
147 if (info->source)
148 ret &= match_type(net, dev, addr: iph->saddr, mask: info->source) ^
149 (info->flags & XT_ADDRTYPE_INVERT_SOURCE);
150 if (ret && info->dest)
151 ret &= match_type(net, dev, addr: iph->daddr, mask: info->dest) ^
152 !!(info->flags & XT_ADDRTYPE_INVERT_DEST);
153 return ret;
154}
155
156static int addrtype_mt_checkentry_v1(const struct xt_mtchk_param *par)
157{
158 const char *errmsg = "both incoming and outgoing interface limitation cannot be selected";
159 struct xt_addrtype_info_v1 *info = par->matchinfo;
160
161 if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN &&
162 info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT)
163 goto err;
164
165 if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
166 (1 << NF_INET_LOCAL_IN)) &&
167 info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT) {
168 errmsg = "output interface limitation not valid in PREROUTING and INPUT";
169 goto err;
170 }
171
172 if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
173 (1 << NF_INET_LOCAL_OUT)) &&
174 info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN) {
175 errmsg = "input interface limitation not valid in POSTROUTING and OUTPUT";
176 goto err;
177 }
178
179#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
180 if (par->family == NFPROTO_IPV6) {
181 if ((info->source | info->dest) & XT_ADDRTYPE_BLACKHOLE) {
182 errmsg = "ipv6 BLACKHOLE matching not supported";
183 goto err;
184 }
185 if ((info->source | info->dest) >= XT_ADDRTYPE_PROHIBIT) {
186 errmsg = "ipv6 PROHIBIT (THROW, NAT ..) matching not supported";
187 goto err;
188 }
189 if ((info->source | info->dest) & XT_ADDRTYPE_BROADCAST) {
190 errmsg = "ipv6 does not support BROADCAST matching";
191 goto err;
192 }
193 }
194#endif
195 return 0;
196err:
197 pr_info_ratelimited("%s\n", errmsg);
198 return -EINVAL;
199}
200
201static struct xt_match addrtype_mt_reg[] __read_mostly = {
202 {
203 .name = "addrtype",
204 .family = NFPROTO_IPV4,
205 .match = addrtype_mt_v0,
206 .matchsize = sizeof(struct xt_addrtype_info),
207 .me = THIS_MODULE
208 },
209 {
210 .name = "addrtype",
211 .family = NFPROTO_IPV4,
212 .revision = 1,
213 .match = addrtype_mt_v1,
214 .checkentry = addrtype_mt_checkentry_v1,
215 .matchsize = sizeof(struct xt_addrtype_info_v1),
216 .me = THIS_MODULE
217 },
218#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
219 {
220 .name = "addrtype",
221 .family = NFPROTO_IPV6,
222 .revision = 1,
223 .match = addrtype_mt_v1,
224 .checkentry = addrtype_mt_checkentry_v1,
225 .matchsize = sizeof(struct xt_addrtype_info_v1),
226 .me = THIS_MODULE
227 },
228#endif
229};
230
231static int __init addrtype_mt_init(void)
232{
233 return xt_register_matches(match: addrtype_mt_reg,
234 ARRAY_SIZE(addrtype_mt_reg));
235}
236
237static void __exit addrtype_mt_exit(void)
238{
239 xt_unregister_matches(match: addrtype_mt_reg, ARRAY_SIZE(addrtype_mt_reg));
240}
241
242module_init(addrtype_mt_init);
243module_exit(addrtype_mt_exit);
244

source code of linux/net/netfilter/xt_addrtype.c