1/* Kernel module to match ROUTING parameters. */
2
3/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10#include <linux/module.h>
11#include <linux/skbuff.h>
12#include <linux/ipv6.h>
13#include <linux/types.h>
14#include <net/checksum.h>
15#include <net/ipv6.h>
16
17#include <asm/byteorder.h>
18
19#include <linux/netfilter/x_tables.h>
20#include <linux/netfilter_ipv6/ip6_tables.h>
21#include <linux/netfilter_ipv6/ip6t_rt.h>
22
23MODULE_LICENSE("GPL");
24MODULE_DESCRIPTION("Xtables: IPv6 Routing Header match");
25MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
26
27/* Returns 1 if the id is matched by the range, 0 otherwise */
28static inline bool
29segsleft_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert)
30{
31	bool r;
32	pr_debug("segsleft_match:%c 0x%x <= 0x%x <= 0x%x\n",
33		 invert ? '!' : ' ', min, id, max);
34	r = (id >= min && id <= max) ^ invert;
35	pr_debug(" result %s\n", r ? "PASS" : "FAILED");
36	return r;
37}
38
39static bool rt_mt6(const struct sk_buff *skb, struct xt_action_param *par)
40{
41	struct ipv6_rt_hdr _route;
42	const struct ipv6_rt_hdr *rh;
43	const struct ip6t_rt *rtinfo = par->matchinfo;
44	unsigned int temp;
45	unsigned int ptr = 0;
46	unsigned int hdrlen = 0;
47	bool ret = false;
48	struct in6_addr _addr;
49	const struct in6_addr *ap;
50	int err;
51
52	err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL, NULL);
53	if (err < 0) {
54		if (err != -ENOENT)
55			par->hotdrop = true;
56		return false;
57	}
58
59	rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
60	if (rh == NULL) {
61		par->hotdrop = true;
62		return false;
63	}
64
65	hdrlen = ipv6_optlen(rh);
66	if (skb->len - ptr < hdrlen) {
67		/* Pcket smaller than its length field */
68		return false;
69	}
70
71	pr_debug("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen);
72	pr_debug("TYPE %04X ", rh->type);
73	pr_debug("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left);
74
75	pr_debug("IPv6 RT segsleft %02X ",
76		 segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
77				rh->segments_left,
78				!!(rtinfo->invflags & IP6T_RT_INV_SGS)));
79	pr_debug("type %02X %02X %02X ",
80		 rtinfo->rt_type, rh->type,
81		 (!(rtinfo->flags & IP6T_RT_TYP) ||
82		  ((rtinfo->rt_type == rh->type) ^
83		   !!(rtinfo->invflags & IP6T_RT_INV_TYP))));
84	pr_debug("len %02X %04X %02X ",
85		 rtinfo->hdrlen, hdrlen,
86		 !(rtinfo->flags & IP6T_RT_LEN) ||
87		  ((rtinfo->hdrlen == hdrlen) ^
88		   !!(rtinfo->invflags & IP6T_RT_INV_LEN)));
89	pr_debug("res %02X %02X %02X ",
90		 rtinfo->flags & IP6T_RT_RES,
91		 ((const struct rt0_hdr *)rh)->reserved,
92		 !((rtinfo->flags & IP6T_RT_RES) &&
93		   (((const struct rt0_hdr *)rh)->reserved)));
94
95	ret = (rh != NULL) &&
96	      (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
97			      rh->segments_left,
98			      !!(rtinfo->invflags & IP6T_RT_INV_SGS))) &&
99	      (!(rtinfo->flags & IP6T_RT_LEN) ||
100	       ((rtinfo->hdrlen == hdrlen) ^
101		!!(rtinfo->invflags & IP6T_RT_INV_LEN))) &&
102	      (!(rtinfo->flags & IP6T_RT_TYP) ||
103	       ((rtinfo->rt_type == rh->type) ^
104		!!(rtinfo->invflags & IP6T_RT_INV_TYP)));
105
106	if (ret && (rtinfo->flags & IP6T_RT_RES)) {
107		const u_int32_t *rp;
108		u_int32_t _reserved;
109		rp = skb_header_pointer(skb,
110					ptr + offsetof(struct rt0_hdr,
111						       reserved),
112					sizeof(_reserved),
113					&_reserved);
114
115		ret = (*rp == 0);
116	}
117
118	pr_debug("#%d ", rtinfo->addrnr);
119	if (!(rtinfo->flags & IP6T_RT_FST)) {
120		return ret;
121	} else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
122		pr_debug("Not strict ");
123		if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
124			pr_debug("There isn't enough space\n");
125			return false;
126		} else {
127			unsigned int i = 0;
128
129			pr_debug("#%d ", rtinfo->addrnr);
130			for (temp = 0;
131			     temp < (unsigned int)((hdrlen - 8) / 16);
132			     temp++) {
133				ap = skb_header_pointer(skb,
134							ptr
135							+ sizeof(struct rt0_hdr)
136							+ temp * sizeof(_addr),
137							sizeof(_addr),
138							&_addr);
139
140				BUG_ON(ap == NULL);
141
142				if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
143					pr_debug("i=%d temp=%d;\n", i, temp);
144					i++;
145				}
146				if (i == rtinfo->addrnr)
147					break;
148			}
149			pr_debug("i=%d #%d\n", i, rtinfo->addrnr);
150			if (i == rtinfo->addrnr)
151				return ret;
152			else
153				return false;
154		}
155	} else {
156		pr_debug("Strict ");
157		if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
158			pr_debug("There isn't enough space\n");
159			return false;
160		} else {
161			pr_debug("#%d ", rtinfo->addrnr);
162			for (temp = 0; temp < rtinfo->addrnr; temp++) {
163				ap = skb_header_pointer(skb,
164							ptr
165							+ sizeof(struct rt0_hdr)
166							+ temp * sizeof(_addr),
167							sizeof(_addr),
168							&_addr);
169				BUG_ON(ap == NULL);
170
171				if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
172					break;
173			}
174			pr_debug("temp=%d #%d\n", temp, rtinfo->addrnr);
175			if (temp == rtinfo->addrnr &&
176			    temp == (unsigned int)((hdrlen - 8) / 16))
177				return ret;
178			else
179				return false;
180		}
181	}
182
183	return false;
184}
185
186static int rt_mt6_check(const struct xt_mtchk_param *par)
187{
188	const struct ip6t_rt *rtinfo = par->matchinfo;
189
190	if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
191		pr_debug("unknown flags %X\n", rtinfo->invflags);
192		return -EINVAL;
193	}
194	if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
195	    (!(rtinfo->flags & IP6T_RT_TYP) ||
196	     (rtinfo->rt_type != 0) ||
197	     (rtinfo->invflags & IP6T_RT_INV_TYP))) {
198		pr_debug("`--rt-type 0' required before `--rt-0-*'");
199		return -EINVAL;
200	}
201
202	return 0;
203}
204
205static struct xt_match rt_mt6_reg __read_mostly = {
206	.name		= "rt",
207	.family		= NFPROTO_IPV6,
208	.match		= rt_mt6,
209	.matchsize	= sizeof(struct ip6t_rt),
210	.checkentry	= rt_mt6_check,
211	.me		= THIS_MODULE,
212};
213
214static int __init rt_mt6_init(void)
215{
216	return xt_register_match(&rt_mt6_reg);
217}
218
219static void __exit rt_mt6_exit(void)
220{
221	xt_unregister_match(&rt_mt6_reg);
222}
223
224module_init(rt_mt6_init);
225module_exit(rt_mt6_exit);
226