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
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
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 /* 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
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_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
171 static 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
180 static int __init rt_mt6_init(void)
181 {
182 return xt_register_match(&rt_mt6_reg);
183 }
184
185 static void __exit rt_mt6_exit(void)
186 {
187 xt_unregister_match(&rt_mt6_reg);
188 }
189
190 module_init(rt_mt6_init);
191 module_exit(rt_mt6_exit);
192
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