Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * ebt_among | |
3 | * | |
4 | * Authors: | |
5 | * Grzegorz Borowiak <grzes@gnu.univ.gda.pl> | |
6 | * | |
7 | * August, 2003 | |
8 | * | |
9 | */ | |
ff67e4e4 | 10 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
1da177e4 LT |
11 | #include <linux/ip.h> |
12 | #include <linux/if_arp.h> | |
13 | #include <linux/module.h> | |
043ef46c JE |
14 | #include <linux/netfilter/x_tables.h> |
15 | #include <linux/netfilter_bridge/ebtables.h> | |
16 | #include <linux/netfilter_bridge/ebt_among.h> | |
1da177e4 | 17 | |
8cc784ee JE |
18 | static bool ebt_mac_wormhash_contains(const struct ebt_mac_wormhash *wh, |
19 | const char *mac, __be32 ip) | |
1da177e4 LT |
20 | { |
21 | /* You may be puzzled as to how this code works. | |
9d6f229f | 22 | * Some tricks were used, refer to |
1da177e4 LT |
23 | * include/linux/netfilter_bridge/ebt_among.h |
24 | * as there you can find a solution of this mystery. | |
25 | */ | |
26 | const struct ebt_mac_wormhash_tuple *p; | |
27 | int start, limit, i; | |
28 | uint32_t cmp[2] = { 0, 0 }; | |
abfdf1c4 | 29 | int key = ((const unsigned char *)mac)[5]; |
1da177e4 | 30 | |
04091142 | 31 | ether_addr_copy(((char *) cmp) + 2, mac); |
1da177e4 LT |
32 | start = wh->table[key]; |
33 | limit = wh->table[key + 1]; | |
34 | if (ip) { | |
35 | for (i = start; i < limit; i++) { | |
36 | p = &wh->pool[i]; | |
8cc784ee JE |
37 | if (cmp[1] == p->cmp[1] && cmp[0] == p->cmp[0]) |
38 | if (p->ip == 0 || p->ip == ip) | |
39 | return true; | |
1da177e4 LT |
40 | } |
41 | } else { | |
42 | for (i = start; i < limit; i++) { | |
43 | p = &wh->pool[i]; | |
8cc784ee JE |
44 | if (cmp[1] == p->cmp[1] && cmp[0] == p->cmp[0]) |
45 | if (p->ip == 0) | |
46 | return true; | |
1da177e4 LT |
47 | } |
48 | } | |
8cc784ee | 49 | return false; |
1da177e4 LT |
50 | } |
51 | ||
52 | static int ebt_mac_wormhash_check_integrity(const struct ebt_mac_wormhash | |
53 | *wh) | |
54 | { | |
55 | int i; | |
56 | ||
57 | for (i = 0; i < 256; i++) { | |
58 | if (wh->table[i] > wh->table[i + 1]) | |
59 | return -0x100 - i; | |
60 | if (wh->table[i] < 0) | |
61 | return -0x200 - i; | |
62 | if (wh->table[i] > wh->poolsize) | |
63 | return -0x300 - i; | |
64 | } | |
65 | if (wh->table[256] > wh->poolsize) | |
66 | return -0xc00; | |
67 | return 0; | |
68 | } | |
69 | ||
47c183fa | 70 | static int get_ip_dst(const struct sk_buff *skb, __be32 *addr) |
1da177e4 LT |
71 | { |
72 | if (eth_hdr(skb)->h_proto == htons(ETH_P_IP)) { | |
abfdf1c4 JE |
73 | const struct iphdr *ih; |
74 | struct iphdr _iph; | |
1da177e4 LT |
75 | |
76 | ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph); | |
77 | if (ih == NULL) | |
78 | return -1; | |
79 | *addr = ih->daddr; | |
80 | } else if (eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) { | |
abfdf1c4 JE |
81 | const struct arphdr *ah; |
82 | struct arphdr _arph; | |
83 | const __be32 *bp; | |
84 | __be32 buf; | |
1da177e4 LT |
85 | |
86 | ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph); | |
87 | if (ah == NULL || | |
47c183fa | 88 | ah->ar_pln != sizeof(__be32) || |
1da177e4 LT |
89 | ah->ar_hln != ETH_ALEN) |
90 | return -1; | |
91 | bp = skb_header_pointer(skb, sizeof(struct arphdr) + | |
47c183fa AV |
92 | 2 * ETH_ALEN + sizeof(__be32), |
93 | sizeof(__be32), &buf); | |
1da177e4 LT |
94 | if (bp == NULL) |
95 | return -1; | |
96 | *addr = *bp; | |
97 | } | |
98 | return 0; | |
99 | } | |
100 | ||
47c183fa | 101 | static int get_ip_src(const struct sk_buff *skb, __be32 *addr) |
1da177e4 LT |
102 | { |
103 | if (eth_hdr(skb)->h_proto == htons(ETH_P_IP)) { | |
abfdf1c4 JE |
104 | const struct iphdr *ih; |
105 | struct iphdr _iph; | |
1da177e4 LT |
106 | |
107 | ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph); | |
108 | if (ih == NULL) | |
109 | return -1; | |
110 | *addr = ih->saddr; | |
111 | } else if (eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) { | |
abfdf1c4 JE |
112 | const struct arphdr *ah; |
113 | struct arphdr _arph; | |
114 | const __be32 *bp; | |
115 | __be32 buf; | |
1da177e4 LT |
116 | |
117 | ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph); | |
118 | if (ah == NULL || | |
47c183fa | 119 | ah->ar_pln != sizeof(__be32) || |
1da177e4 LT |
120 | ah->ar_hln != ETH_ALEN) |
121 | return -1; | |
122 | bp = skb_header_pointer(skb, sizeof(struct arphdr) + | |
47c183fa | 123 | ETH_ALEN, sizeof(__be32), &buf); |
1da177e4 LT |
124 | if (bp == NULL) |
125 | return -1; | |
126 | *addr = *bp; | |
127 | } | |
128 | return 0; | |
129 | } | |
130 | ||
2d06d4a5 | 131 | static bool |
62fc8051 | 132 | ebt_among_mt(const struct sk_buff *skb, struct xt_action_param *par) |
1da177e4 | 133 | { |
f7108a20 | 134 | const struct ebt_among_info *info = par->matchinfo; |
1da177e4 LT |
135 | const char *dmac, *smac; |
136 | const struct ebt_mac_wormhash *wh_dst, *wh_src; | |
47c183fa | 137 | __be32 dip = 0, sip = 0; |
1da177e4 LT |
138 | |
139 | wh_dst = ebt_among_wh_dst(info); | |
140 | wh_src = ebt_among_wh_src(info); | |
141 | ||
142 | if (wh_src) { | |
143 | smac = eth_hdr(skb)->h_source; | |
144 | if (get_ip_src(skb, &sip)) | |
8cc784ee | 145 | return false; |
1da177e4 LT |
146 | if (!(info->bitmask & EBT_AMONG_SRC_NEG)) { |
147 | /* we match only if it contains */ | |
148 | if (!ebt_mac_wormhash_contains(wh_src, smac, sip)) | |
8cc784ee | 149 | return false; |
1da177e4 LT |
150 | } else { |
151 | /* we match only if it DOES NOT contain */ | |
152 | if (ebt_mac_wormhash_contains(wh_src, smac, sip)) | |
8cc784ee | 153 | return false; |
1da177e4 LT |
154 | } |
155 | } | |
156 | ||
157 | if (wh_dst) { | |
158 | dmac = eth_hdr(skb)->h_dest; | |
159 | if (get_ip_dst(skb, &dip)) | |
8cc784ee | 160 | return false; |
1da177e4 LT |
161 | if (!(info->bitmask & EBT_AMONG_DST_NEG)) { |
162 | /* we match only if it contains */ | |
163 | if (!ebt_mac_wormhash_contains(wh_dst, dmac, dip)) | |
8cc784ee | 164 | return false; |
1da177e4 LT |
165 | } else { |
166 | /* we match only if it DOES NOT contain */ | |
167 | if (ebt_mac_wormhash_contains(wh_dst, dmac, dip)) | |
8cc784ee | 168 | return false; |
1da177e4 LT |
169 | } |
170 | } | |
171 | ||
8cc784ee | 172 | return true; |
1da177e4 LT |
173 | } |
174 | ||
b0f38452 | 175 | static int ebt_among_mt_check(const struct xt_mtchk_param *par) |
1da177e4 | 176 | { |
9b4fce7a | 177 | const struct ebt_among_info *info = par->matchinfo; |
815377fe | 178 | const struct ebt_entry_match *em = |
9b4fce7a | 179 | container_of(par->matchinfo, const struct ebt_entry_match, data); |
1da177e4 LT |
180 | int expected_length = sizeof(struct ebt_among_info); |
181 | const struct ebt_mac_wormhash *wh_dst, *wh_src; | |
182 | int err; | |
183 | ||
184 | wh_dst = ebt_among_wh_dst(info); | |
185 | wh_src = ebt_among_wh_src(info); | |
186 | expected_length += ebt_mac_wormhash_size(wh_dst); | |
187 | expected_length += ebt_mac_wormhash_size(wh_src); | |
188 | ||
815377fe | 189 | if (em->match_size != EBT_ALIGN(expected_length)) { |
ff67e4e4 JE |
190 | pr_info("wrong size: %d against expected %d, rounded to %Zd\n", |
191 | em->match_size, expected_length, | |
192 | EBT_ALIGN(expected_length)); | |
bd414ee6 | 193 | return -EINVAL; |
1da177e4 LT |
194 | } |
195 | if (wh_dst && (err = ebt_mac_wormhash_check_integrity(wh_dst))) { | |
ff67e4e4 | 196 | pr_info("dst integrity fail: %x\n", -err); |
bd414ee6 | 197 | return -EINVAL; |
1da177e4 LT |
198 | } |
199 | if (wh_src && (err = ebt_mac_wormhash_check_integrity(wh_src))) { | |
ff67e4e4 | 200 | pr_info("src integrity fail: %x\n", -err); |
bd414ee6 | 201 | return -EINVAL; |
1da177e4 | 202 | } |
bd414ee6 | 203 | return 0; |
1da177e4 LT |
204 | } |
205 | ||
043ef46c JE |
206 | static struct xt_match ebt_among_mt_reg __read_mostly = { |
207 | .name = "among", | |
001a18d3 JE |
208 | .revision = 0, |
209 | .family = NFPROTO_BRIDGE, | |
2d06d4a5 JE |
210 | .match = ebt_among_mt, |
211 | .checkentry = ebt_among_mt_check, | |
18219d3f | 212 | .matchsize = -1, /* special case */ |
1da177e4 LT |
213 | .me = THIS_MODULE, |
214 | }; | |
215 | ||
65b4b4e8 | 216 | static int __init ebt_among_init(void) |
1da177e4 | 217 | { |
043ef46c | 218 | return xt_register_match(&ebt_among_mt_reg); |
1da177e4 LT |
219 | } |
220 | ||
65b4b4e8 | 221 | static void __exit ebt_among_fini(void) |
1da177e4 | 222 | { |
043ef46c | 223 | xt_unregister_match(&ebt_among_mt_reg); |
1da177e4 LT |
224 | } |
225 | ||
65b4b4e8 AM |
226 | module_init(ebt_among_init); |
227 | module_exit(ebt_among_fini); | |
f776c4cd | 228 | MODULE_DESCRIPTION("Ebtables: Combined MAC/IP address list matching"); |
1da177e4 | 229 | MODULE_LICENSE("GPL"); |