1// SPDX-License-Identifier: GPL-2.0-only
2/* Kernel module to match ROUTING parameters. */
3
4/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
5 */
6#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
7#include <linux/module.h>
8#include <linux/skbuff.h>
9#include <linux/ipv6.h>
10#include <linux/types.h>
11#include <net/checksum.h>
12#include <net/ipv6.h>
13
14#include <asm/byteorder.h>
15
16#include <linux/netfilter/x_tables.h>
17#include <linux/netfilter_ipv6/ip6_tables.h>
18#include <linux/netfilter_ipv6/ip6t_rt.h>
19
20MODULE_LICENSE("GPL");
21MODULE_DESCRIPTION("Xtables: IPv6 Routing Header match");
22MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
23
24/* Returns 1 if the id is matched by the range, 0 otherwise */
25static inline bool
26segsleft_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert)
27{
28	return (id >= min && id <= max) ^ invert;
29}
30
31static bool rt_mt6(const struct sk_buff *skb, struct xt_action_param *par)
32{
33	struct ipv6_rt_hdr _route;
34	const struct ipv6_rt_hdr *rh;
35	const struct ip6t_rt *rtinfo = par->matchinfo;
36	unsigned int temp;
37	unsigned int ptr = 0;
38	unsigned int hdrlen = 0;
39	bool ret = false;
40	struct in6_addr _addr;
41	const struct in6_addr *ap;
42	int err;
43
44	err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL, NULL);
45	if (err < 0) {
46		if (err != -ENOENT)
47			par->hotdrop = true;
48		return false;
49	}
50
51	rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
52	if (rh == NULL) {
53		par->hotdrop = true;
54		return false;
55	}
56
57	hdrlen = ipv6_optlen(rh);
58	if (skb->len - ptr < hdrlen) {
59		/* Pcket smaller than its length field */
60		return false;
61	}
62
63	ret = (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
64			      rh->segments_left,
65			      !!(rtinfo->invflags & IP6T_RT_INV_SGS))) &&
66	      (!(rtinfo->flags & IP6T_RT_LEN) ||
67	       ((rtinfo->hdrlen == hdrlen) ^
68		!!(rtinfo->invflags & IP6T_RT_INV_LEN))) &&
69	      (!(rtinfo->flags & IP6T_RT_TYP) ||
70	       ((rtinfo->rt_type == rh->type) ^
71		!!(rtinfo->invflags & IP6T_RT_INV_TYP)));
72
73	if (ret && (rtinfo->flags & IP6T_RT_RES)) {
74		const u_int32_t *rp;
75		u_int32_t _reserved;
76		rp = skb_header_pointer(skb,
77					ptr + offsetof(struct rt0_hdr,
78						       reserved),
79					sizeof(_reserved),
80					&_reserved);
81		if (!rp) {
82			par->hotdrop = true;
83			return false;
84		}
85
86		ret = (*rp == 0);
87	}
88
89	if (!(rtinfo->flags & IP6T_RT_FST)) {
90		return ret;
91	} else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
92		if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
93			return false;
94		} else {
95			unsigned int i = 0;
96
97			for (temp = 0;
98			     temp < (unsigned int)((hdrlen - 8) / 16);
99			     temp++) {
100				ap = skb_header_pointer(skb,
101							ptr
102							+ sizeof(struct rt0_hdr)
103							+ temp * sizeof(_addr),
104							sizeof(_addr),
105							&_addr);
106
107				if (ap == NULL) {
108					par->hotdrop = true;
109					return false;
110				}
111
112				if (ipv6_addr_equal(ap, &rtinfo->addrs[i]))
113					i++;
114				if (i == rtinfo->addrnr)
115					break;
116			}
117			if (i == rtinfo->addrnr)
118				return ret;
119			else
120				return false;
121		}
122	} else {
123		if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
124			return false;
125		} else {
126			for (temp = 0; temp < rtinfo->addrnr; temp++) {
127				ap = skb_header_pointer(skb,
128							ptr
129							+ sizeof(struct rt0_hdr)
130							+ temp * sizeof(_addr),
131							sizeof(_addr),
132							&_addr);
133				if (ap == NULL) {
134					par->hotdrop = true;
135					return false;
136				}
137
138				if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
139					break;
140			}
141			if (temp == rtinfo->addrnr &&
142			    temp == (unsigned int)((hdrlen - 8) / 16))
143				return ret;
144			else
145				return false;
146		}
147	}
148
149	return false;
150}
151
152static int rt_mt6_check(const struct xt_mtchk_param *par)
153{
154	const struct ip6t_rt *rtinfo = par->matchinfo;
155
156	if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
157		pr_debug("unknown flags %X\n", rtinfo->invflags);
158		return -EINVAL;
159	}
160	if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
161	    (!(rtinfo->flags & IP6T_RT_TYP) ||
162	     (rtinfo->rt_type != 0) ||
163	     (rtinfo->invflags & IP6T_RT_INV_TYP))) {
164		pr_debug("`--rt-type 0' required before `--rt-0-*'");
165		return -EINVAL;
166	}
167
168	return 0;
169}
170
171static struct xt_match rt_mt6_reg __read_mostly = {
172	.name		= "rt",
173	.family		= NFPROTO_IPV6,
174	.match		= rt_mt6,
175	.matchsize	= sizeof(struct ip6t_rt),
176	.checkentry	= rt_mt6_check,
177	.me		= THIS_MODULE,
178};
179
180static int __init rt_mt6_init(void)
181{
182	return xt_register_match(&rt_mt6_reg);
183}
184
185static void __exit rt_mt6_exit(void)
186{
187	xt_unregister_match(&rt_mt6_reg);
188}
189
190module_init(rt_mt6_init);
191module_exit(rt_mt6_exit);
192