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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * ebt_arp | |
3 | * | |
4 | * Authors: | |
5 | * Bart De Schuymer <bdschuym@pandora.be> | |
6 | * Tim Gardner <timg@tpi.com> | |
7 | * | |
8 | * April, 2002 | |
9 | * | |
10 | */ | |
1da177e4 LT |
11 | #include <linux/if_arp.h> |
12 | #include <linux/if_ether.h> | |
13 | #include <linux/module.h> | |
18219d3f JE |
14 | #include <linux/netfilter/x_tables.h> |
15 | #include <linux/netfilter_bridge/ebtables.h> | |
16 | #include <linux/netfilter_bridge/ebt_arp.h> | |
1da177e4 | 17 | |
2d06d4a5 | 18 | static bool |
f7108a20 | 19 | ebt_arp_mt(const struct sk_buff *skb, const struct xt_match_param *par) |
1da177e4 | 20 | { |
f7108a20 | 21 | const struct ebt_arp_info *info = par->matchinfo; |
abfdf1c4 JE |
22 | const struct arphdr *ah; |
23 | struct arphdr _arph; | |
1da177e4 LT |
24 | |
25 | ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph); | |
26 | if (ah == NULL) | |
8cc784ee | 27 | return false; |
1da177e4 LT |
28 | if (info->bitmask & EBT_ARP_OPCODE && FWINV(info->opcode != |
29 | ah->ar_op, EBT_ARP_OPCODE)) | |
8cc784ee | 30 | return false; |
1da177e4 LT |
31 | if (info->bitmask & EBT_ARP_HTYPE && FWINV(info->htype != |
32 | ah->ar_hrd, EBT_ARP_HTYPE)) | |
8cc784ee | 33 | return false; |
1da177e4 LT |
34 | if (info->bitmask & EBT_ARP_PTYPE && FWINV(info->ptype != |
35 | ah->ar_pro, EBT_ARP_PTYPE)) | |
8cc784ee | 36 | return false; |
1da177e4 | 37 | |
e011ff48 | 38 | if (info->bitmask & (EBT_ARP_SRC_IP | EBT_ARP_DST_IP | EBT_ARP_GRAT)) { |
abfdf1c4 JE |
39 | const __be32 *sap, *dap; |
40 | __be32 saddr, daddr; | |
1da177e4 | 41 | |
c15bf6e6 | 42 | if (ah->ar_pln != sizeof(__be32) || ah->ar_pro != htons(ETH_P_IP)) |
8cc784ee | 43 | return false; |
c15bf6e6 BDS |
44 | sap = skb_header_pointer(skb, sizeof(struct arphdr) + |
45 | ah->ar_hln, sizeof(saddr), | |
46 | &saddr); | |
47 | if (sap == NULL) | |
8cc784ee | 48 | return false; |
c15bf6e6 BDS |
49 | dap = skb_header_pointer(skb, sizeof(struct arphdr) + |
50 | 2*ah->ar_hln+sizeof(saddr), | |
51 | sizeof(daddr), &daddr); | |
52 | if (dap == NULL) | |
8cc784ee | 53 | return false; |
c15bf6e6 BDS |
54 | if (info->bitmask & EBT_ARP_SRC_IP && |
55 | FWINV(info->saddr != (*sap & info->smsk), EBT_ARP_SRC_IP)) | |
8cc784ee | 56 | return false; |
c15bf6e6 BDS |
57 | if (info->bitmask & EBT_ARP_DST_IP && |
58 | FWINV(info->daddr != (*dap & info->dmsk), EBT_ARP_DST_IP)) | |
8cc784ee | 59 | return false; |
c15bf6e6 BDS |
60 | if (info->bitmask & EBT_ARP_GRAT && |
61 | FWINV(*dap != *sap, EBT_ARP_GRAT)) | |
8cc784ee | 62 | return false; |
1da177e4 LT |
63 | } |
64 | ||
65 | if (info->bitmask & (EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC)) { | |
abfdf1c4 JE |
66 | const unsigned char *mp; |
67 | unsigned char _mac[ETH_ALEN]; | |
1da177e4 LT |
68 | uint8_t verdict, i; |
69 | ||
c15bf6e6 | 70 | if (ah->ar_hln != ETH_ALEN || ah->ar_hrd != htons(ARPHRD_ETHER)) |
8cc784ee | 71 | return false; |
1da177e4 LT |
72 | if (info->bitmask & EBT_ARP_SRC_MAC) { |
73 | mp = skb_header_pointer(skb, sizeof(struct arphdr), | |
74 | sizeof(_mac), &_mac); | |
75 | if (mp == NULL) | |
8cc784ee | 76 | return false; |
1da177e4 LT |
77 | verdict = 0; |
78 | for (i = 0; i < 6; i++) | |
79 | verdict |= (mp[i] ^ info->smaddr[i]) & | |
80 | info->smmsk[i]; | |
81 | if (FWINV(verdict != 0, EBT_ARP_SRC_MAC)) | |
8cc784ee | 82 | return false; |
1da177e4 LT |
83 | } |
84 | ||
85 | if (info->bitmask & EBT_ARP_DST_MAC) { | |
86 | mp = skb_header_pointer(skb, sizeof(struct arphdr) + | |
87 | ah->ar_hln + ah->ar_pln, | |
88 | sizeof(_mac), &_mac); | |
89 | if (mp == NULL) | |
8cc784ee | 90 | return false; |
1da177e4 LT |
91 | verdict = 0; |
92 | for (i = 0; i < 6; i++) | |
93 | verdict |= (mp[i] ^ info->dmaddr[i]) & | |
94 | info->dmmsk[i]; | |
95 | if (FWINV(verdict != 0, EBT_ARP_DST_MAC)) | |
8cc784ee | 96 | return false; |
1da177e4 LT |
97 | } |
98 | } | |
99 | ||
8cc784ee | 100 | return true; |
1da177e4 LT |
101 | } |
102 | ||
9b4fce7a | 103 | static bool ebt_arp_mt_check(const struct xt_mtchk_param *par) |
1da177e4 | 104 | { |
9b4fce7a JE |
105 | const struct ebt_arp_info *info = par->matchinfo; |
106 | const struct ebt_entry *e = par->entryinfo; | |
1da177e4 | 107 | |
1da177e4 LT |
108 | if ((e->ethproto != htons(ETH_P_ARP) && |
109 | e->ethproto != htons(ETH_P_RARP)) || | |
110 | e->invflags & EBT_IPROTO) | |
19eda879 | 111 | return false; |
1da177e4 | 112 | if (info->bitmask & ~EBT_ARP_MASK || info->invflags & ~EBT_ARP_MASK) |
19eda879 JE |
113 | return false; |
114 | return true; | |
1da177e4 LT |
115 | } |
116 | ||
043ef46c JE |
117 | static struct xt_match ebt_arp_mt_reg __read_mostly = { |
118 | .name = "arp", | |
001a18d3 JE |
119 | .revision = 0, |
120 | .family = NFPROTO_BRIDGE, | |
2d06d4a5 JE |
121 | .match = ebt_arp_mt, |
122 | .checkentry = ebt_arp_mt_check, | |
18219d3f | 123 | .matchsize = XT_ALIGN(sizeof(struct ebt_arp_info)), |
1da177e4 LT |
124 | .me = THIS_MODULE, |
125 | }; | |
126 | ||
65b4b4e8 | 127 | static int __init ebt_arp_init(void) |
1da177e4 | 128 | { |
043ef46c | 129 | return xt_register_match(&ebt_arp_mt_reg); |
1da177e4 LT |
130 | } |
131 | ||
65b4b4e8 | 132 | static void __exit ebt_arp_fini(void) |
1da177e4 | 133 | { |
043ef46c | 134 | xt_unregister_match(&ebt_arp_mt_reg); |
1da177e4 LT |
135 | } |
136 | ||
65b4b4e8 AM |
137 | module_init(ebt_arp_init); |
138 | module_exit(ebt_arp_fini); | |
f776c4cd | 139 | MODULE_DESCRIPTION("Ebtables: ARP protocol packet match"); |
1da177e4 | 140 | MODULE_LICENSE("GPL"); |