1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* ipv6header match - matches IPv6 packets based |
3 | on whether they contain certain headers */ |
4 | |
5 | /* Original idea: Brad Chapman |
6 | * Rewritten by: Andras Kis-Szabo <kisza@sch.bme.hu> */ |
7 | |
8 | /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> |
9 | */ |
10 | |
11 | #include <linux/module.h> |
12 | #include <linux/skbuff.h> |
13 | #include <linux/ipv6.h> |
14 | #include <linux/types.h> |
15 | #include <net/checksum.h> |
16 | #include <net/ipv6.h> |
17 | |
18 | #include <linux/netfilter/x_tables.h> |
19 | #include <linux/netfilter_ipv6.h> |
20 | #include <linux/netfilter_ipv6/ip6t_ipv6header.h> |
21 | |
22 | MODULE_LICENSE("GPL" ); |
23 | MODULE_DESCRIPTION("Xtables: IPv6 header types match" ); |
24 | MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>" ); |
25 | |
26 | static bool |
27 | (const struct sk_buff *skb, struct xt_action_param *par) |
28 | { |
29 | const struct ip6t_ipv6header_info *info = par->matchinfo; |
30 | unsigned int temp; |
31 | int len; |
32 | u8 nexthdr; |
33 | unsigned int ptr; |
34 | |
35 | /* Make sure this isn't an evil packet */ |
36 | |
37 | /* type of the 1st exthdr */ |
38 | nexthdr = ipv6_hdr(skb)->nexthdr; |
39 | /* pointer to the 1st exthdr */ |
40 | ptr = sizeof(struct ipv6hdr); |
41 | /* available length */ |
42 | len = skb->len - ptr; |
43 | temp = 0; |
44 | |
45 | while (nf_ip6_ext_hdr(nexthdr)) { |
46 | const struct ipv6_opt_hdr *hp; |
47 | struct ipv6_opt_hdr _hdr; |
48 | int hdrlen; |
49 | |
50 | /* No more exthdr -> evaluate */ |
51 | if (nexthdr == NEXTHDR_NONE) { |
52 | temp |= MASK_NONE; |
53 | break; |
54 | } |
55 | /* Is there enough space for the next ext header? */ |
56 | if (len < (int)sizeof(struct ipv6_opt_hdr)) |
57 | return false; |
58 | /* ESP -> evaluate */ |
59 | if (nexthdr == NEXTHDR_ESP) { |
60 | temp |= MASK_ESP; |
61 | break; |
62 | } |
63 | |
64 | hp = skb_header_pointer(skb, offset: ptr, len: sizeof(_hdr), buffer: &_hdr); |
65 | if (!hp) { |
66 | par->hotdrop = true; |
67 | return false; |
68 | } |
69 | |
70 | /* Calculate the header length */ |
71 | if (nexthdr == NEXTHDR_FRAGMENT) |
72 | hdrlen = 8; |
73 | else if (nexthdr == NEXTHDR_AUTH) |
74 | hdrlen = ipv6_authlen(hp); |
75 | else |
76 | hdrlen = ipv6_optlen(hp); |
77 | |
78 | /* set the flag */ |
79 | switch (nexthdr) { |
80 | case NEXTHDR_HOP: |
81 | temp |= MASK_HOPOPTS; |
82 | break; |
83 | case NEXTHDR_ROUTING: |
84 | temp |= MASK_ROUTING; |
85 | break; |
86 | case NEXTHDR_FRAGMENT: |
87 | temp |= MASK_FRAGMENT; |
88 | break; |
89 | case NEXTHDR_AUTH: |
90 | temp |= MASK_AH; |
91 | break; |
92 | case NEXTHDR_DEST: |
93 | temp |= MASK_DSTOPTS; |
94 | break; |
95 | default: |
96 | return false; |
97 | } |
98 | |
99 | nexthdr = hp->nexthdr; |
100 | len -= hdrlen; |
101 | ptr += hdrlen; |
102 | if (ptr > skb->len) |
103 | break; |
104 | } |
105 | |
106 | if (nexthdr != NEXTHDR_NONE && nexthdr != NEXTHDR_ESP) |
107 | temp |= MASK_PROTO; |
108 | |
109 | if (info->modeflag) |
110 | return !((temp ^ info->matchflags ^ info->invflags) |
111 | & info->matchflags); |
112 | else { |
113 | if (info->invflags) |
114 | return temp != info->matchflags; |
115 | else |
116 | return temp == info->matchflags; |
117 | } |
118 | } |
119 | |
120 | static int (const struct xt_mtchk_param *par) |
121 | { |
122 | const struct ip6t_ipv6header_info *info = par->matchinfo; |
123 | |
124 | /* invflags is 0 or 0xff in hard mode */ |
125 | if ((!info->modeflag) && info->invflags != 0x00 && |
126 | info->invflags != 0xFF) |
127 | return -EINVAL; |
128 | |
129 | return 0; |
130 | } |
131 | |
132 | static struct xt_match __read_mostly = { |
133 | .name = "ipv6header" , |
134 | .family = NFPROTO_IPV6, |
135 | .match = ipv6header_mt6, |
136 | .matchsize = sizeof(struct ip6t_ipv6header_info), |
137 | .checkentry = ipv6header_mt6_check, |
138 | .destroy = NULL, |
139 | .me = THIS_MODULE, |
140 | }; |
141 | |
142 | static int __init (void) |
143 | { |
144 | return xt_register_match(target: &ipv6header_mt6_reg); |
145 | } |
146 | |
147 | static void __exit (void) |
148 | { |
149 | xt_unregister_match(target: &ipv6header_mt6_reg); |
150 | } |
151 | |
152 | module_init(ipv6header_mt6_init); |
153 | module_exit(ipv6header_mt6_exit); |
154 | |