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
20 MODULE_LICENSE("GPL");
21 MODULE_DESCRIPTION("Xtables: IPv6 Routing Header match");
22 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
23
24 /* Returns 1 if the id is matched by the range, 0 otherwise */
25 static inline bool
segsleft_match(u_int32_t min,u_int32_t max,u_int32_t id,bool invert)26 segsleft_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
rt_mt6(const struct sk_buff * skb,struct xt_action_param * par)31 static 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 /* Packet smaller than its length field */
60 par->hotdrop = true;
61 return false;
62 }
63
64 ret = (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
65 rh->segments_left,
66 !!(rtinfo->invflags & IP6T_RT_INV_SGS))) &&
67 (!(rtinfo->flags & IP6T_RT_LEN) ||
68 ((rtinfo->hdrlen == hdrlen) ^
69 !!(rtinfo->invflags & IP6T_RT_INV_LEN))) &&
70 (!(rtinfo->flags & IP6T_RT_TYP) ||
71 ((rtinfo->rt_type == rh->type) ^
72 !!(rtinfo->invflags & IP6T_RT_INV_TYP)));
73
74 if (ret && (rtinfo->flags & IP6T_RT_RES)) {
75 const u_int32_t *rp;
76 u_int32_t _reserved;
77 rp = skb_header_pointer(skb,
78 ptr + offsetof(struct rt0_hdr,
79 reserved),
80 sizeof(_reserved),
81 &_reserved);
82 if (!rp) {
83 par->hotdrop = true;
84 return false;
85 }
86
87 ret = (*rp == 0);
88 }
89
90 if (!(rtinfo->flags & IP6T_RT_FST)) {
91 return ret;
92 } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
93 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
94 return false;
95 } else {
96 unsigned int i = 0;
97
98 for (temp = 0;
99 temp < (unsigned int)((hdrlen - 8) / 16) &&
100 i < rtinfo->addrnr;
101 temp++) {
102 ap = skb_header_pointer(skb,
103 ptr
104 + sizeof(struct rt0_hdr)
105 + temp * sizeof(_addr),
106 sizeof(_addr),
107 &_addr);
108
109 if (ap == NULL) {
110 par->hotdrop = true;
111 return false;
112 }
113
114 if (ipv6_addr_equal(ap, &rtinfo->addrs[i]))
115 i++;
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
rt_mt6_check(const struct xt_mtchk_param * par)152 static 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_info_ratelimited("unknown flags %X\n", rtinfo->invflags);
158 return -EINVAL;
159 }
160 if (rtinfo->addrnr > IP6T_RT_HOPS) {
161 pr_info_ratelimited("too many addresses specified\n");
162 return -EINVAL;
163 }
164
165 if ((rtinfo->flags & IP6T_RT_FST_MASK) && !rtinfo->addrnr) {
166 pr_info_ratelimited("address list match requested but addrnr is 0\n");
167 return -EINVAL;
168 }
169
170 if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
171 (!(rtinfo->flags & IP6T_RT_TYP) ||
172 (rtinfo->rt_type != 0) ||
173 (rtinfo->invflags & IP6T_RT_INV_TYP))) {
174 pr_info_ratelimited("`--rt-type 0' required before `--rt-0-*'\n");
175 return -EINVAL;
176 }
177
178 return 0;
179 }
180
181 static struct xt_match rt_mt6_reg __read_mostly = {
182 .name = "rt",
183 .family = NFPROTO_IPV6,
184 .match = rt_mt6,
185 .matchsize = sizeof(struct ip6t_rt),
186 .checkentry = rt_mt6_check,
187 .me = THIS_MODULE,
188 };
189
rt_mt6_init(void)190 static int __init rt_mt6_init(void)
191 {
192 return xt_register_match(&rt_mt6_reg);
193 }
194
rt_mt6_exit(void)195 static void __exit rt_mt6_exit(void)
196 {
197 xt_unregister_match(&rt_mt6_reg);
198 }
199
200 module_init(rt_mt6_init);
201 module_exit(rt_mt6_exit);
202