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10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11#include <linux/ip.h>
12#include <linux/if_arp.h>
13#include <linux/module.h>
14#include <linux/netfilter/x_tables.h>
15#include <linux/netfilter_bridge/ebtables.h>
16#include <linux/netfilter_bridge/ebt_among.h>
17
18static bool ebt_mac_wormhash_contains(const struct ebt_mac_wormhash *wh,
19 const char *mac, __be32 ip)
20{
21
22
23
24
25
26 const struct ebt_mac_wormhash_tuple *p;
27 int start, limit, i;
28 uint32_t cmp[2] = { 0, 0 };
29 int key = ((const unsigned char *)mac)[5];
30
31 memcpy(((char *) cmp) + 2, mac, 6);
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];
37 if (cmp[1] == p->cmp[1] && cmp[0] == p->cmp[0])
38 if (p->ip == 0 || p->ip == ip)
39 return true;
40 }
41 } else {
42 for (i = start; i < limit; i++) {
43 p = &wh->pool[i];
44 if (cmp[1] == p->cmp[1] && cmp[0] == p->cmp[0])
45 if (p->ip == 0)
46 return true;
47 }
48 }
49 return false;
50}
51
52static 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
70static int get_ip_dst(const struct sk_buff *skb, __be32 *addr)
71{
72 if (eth_hdr(skb)->h_proto == htons(ETH_P_IP)) {
73 const struct iphdr *ih;
74 struct iphdr _iph;
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)) {
81 const struct arphdr *ah;
82 struct arphdr _arph;
83 const __be32 *bp;
84 __be32 buf;
85
86 ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
87 if (ah == NULL ||
88 ah->ar_pln != sizeof(__be32) ||
89 ah->ar_hln != ETH_ALEN)
90 return -1;
91 bp = skb_header_pointer(skb, sizeof(struct arphdr) +
92 2 * ETH_ALEN + sizeof(__be32),
93 sizeof(__be32), &buf);
94 if (bp == NULL)
95 return -1;
96 *addr = *bp;
97 }
98 return 0;
99}
100
101static int get_ip_src(const struct sk_buff *skb, __be32 *addr)
102{
103 if (eth_hdr(skb)->h_proto == htons(ETH_P_IP)) {
104 const struct iphdr *ih;
105 struct iphdr _iph;
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)) {
112 const struct arphdr *ah;
113 struct arphdr _arph;
114 const __be32 *bp;
115 __be32 buf;
116
117 ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
118 if (ah == NULL ||
119 ah->ar_pln != sizeof(__be32) ||
120 ah->ar_hln != ETH_ALEN)
121 return -1;
122 bp = skb_header_pointer(skb, sizeof(struct arphdr) +
123 ETH_ALEN, sizeof(__be32), &buf);
124 if (bp == NULL)
125 return -1;
126 *addr = *bp;
127 }
128 return 0;
129}
130
131static bool
132ebt_among_mt(const struct sk_buff *skb, struct xt_action_param *par)
133{
134 const struct ebt_among_info *info = par->matchinfo;
135 const char *dmac, *smac;
136 const struct ebt_mac_wormhash *wh_dst, *wh_src;
137 __be32 dip = 0, sip = 0;
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))
145 return false;
146 if (!(info->bitmask & EBT_AMONG_SRC_NEG)) {
147
148 if (!ebt_mac_wormhash_contains(wh_src, smac, sip))
149 return false;
150 } else {
151
152 if (ebt_mac_wormhash_contains(wh_src, smac, sip))
153 return false;
154 }
155 }
156
157 if (wh_dst) {
158 dmac = eth_hdr(skb)->h_dest;
159 if (get_ip_dst(skb, &dip))
160 return false;
161 if (!(info->bitmask & EBT_AMONG_DST_NEG)) {
162
163 if (!ebt_mac_wormhash_contains(wh_dst, dmac, dip))
164 return false;
165 } else {
166
167 if (ebt_mac_wormhash_contains(wh_dst, dmac, dip))
168 return false;
169 }
170 }
171
172 return true;
173}
174
175static int ebt_among_mt_check(const struct xt_mtchk_param *par)
176{
177 const struct ebt_among_info *info = par->matchinfo;
178 const struct ebt_entry_match *em =
179 container_of(par->matchinfo, const struct ebt_entry_match, data);
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
189 if (em->match_size != EBT_ALIGN(expected_length)) {
190 pr_info("wrong size: %d against expected %d, rounded to %Zd\n",
191 em->match_size, expected_length,
192 EBT_ALIGN(expected_length));
193 return -EINVAL;
194 }
195 if (wh_dst && (err = ebt_mac_wormhash_check_integrity(wh_dst))) {
196 pr_info("dst integrity fail: %x\n", -err);
197 return -EINVAL;
198 }
199 if (wh_src && (err = ebt_mac_wormhash_check_integrity(wh_src))) {
200 pr_info("src integrity fail: %x\n", -err);
201 return -EINVAL;
202 }
203 return 0;
204}
205
206static struct xt_match ebt_among_mt_reg __read_mostly = {
207 .name = "among",
208 .revision = 0,
209 .family = NFPROTO_BRIDGE,
210 .match = ebt_among_mt,
211 .checkentry = ebt_among_mt_check,
212 .matchsize = -1,
213 .me = THIS_MODULE,
214};
215
216static int __init ebt_among_init(void)
217{
218 return xt_register_match(&ebt_among_mt_reg);
219}
220
221static void __exit ebt_among_fini(void)
222{
223 xt_unregister_match(&ebt_among_mt_reg);
224}
225
226module_init(ebt_among_init);
227module_exit(ebt_among_fini);
228MODULE_DESCRIPTION("Ebtables: Combined MAC/IP address list matching");
229MODULE_LICENSE("GPL");
230
