Commit | Line | Data |
---|---|---|
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 | */ | |
11 | ||
12 | #include <linux/netfilter_bridge/ebtables.h> | |
13 | #include <linux/netfilter_bridge/ebt_arp.h> | |
14 | #include <linux/if_arp.h> | |
15 | #include <linux/if_ether.h> | |
16 | #include <linux/module.h> | |
17 | ||
18 | static int ebt_filter_arp(const struct sk_buff *skb, const struct net_device *in, | |
19 | const struct net_device *out, const void *data, unsigned int datalen) | |
20 | { | |
21 | struct ebt_arp_info *info = (struct ebt_arp_info *)data; | |
22 | struct arphdr _arph, *ah; | |
23 | ||
24 | ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph); | |
25 | if (ah == NULL) | |
26 | return EBT_NOMATCH; | |
27 | if (info->bitmask & EBT_ARP_OPCODE && FWINV(info->opcode != | |
28 | ah->ar_op, EBT_ARP_OPCODE)) | |
29 | return EBT_NOMATCH; | |
30 | if (info->bitmask & EBT_ARP_HTYPE && FWINV(info->htype != | |
31 | ah->ar_hrd, EBT_ARP_HTYPE)) | |
32 | return EBT_NOMATCH; | |
33 | if (info->bitmask & EBT_ARP_PTYPE && FWINV(info->ptype != | |
34 | ah->ar_pro, EBT_ARP_PTYPE)) | |
35 | return EBT_NOMATCH; | |
36 | ||
37 | if (info->bitmask & (EBT_ARP_SRC_IP | EBT_ARP_DST_IP)) { | |
38 | uint32_t _addr, *ap; | |
39 | ||
40 | /* IPv4 addresses are always 4 bytes */ | |
41 | if (ah->ar_pln != sizeof(uint32_t)) | |
42 | return EBT_NOMATCH; | |
43 | if (info->bitmask & EBT_ARP_SRC_IP) { | |
44 | ap = skb_header_pointer(skb, sizeof(struct arphdr) + | |
45 | ah->ar_hln, sizeof(_addr), | |
46 | &_addr); | |
47 | if (ap == NULL) | |
48 | return EBT_NOMATCH; | |
49 | if (FWINV(info->saddr != (*ap & info->smsk), | |
50 | EBT_ARP_SRC_IP)) | |
51 | return EBT_NOMATCH; | |
52 | } | |
53 | ||
54 | if (info->bitmask & EBT_ARP_DST_IP) { | |
55 | ap = skb_header_pointer(skb, sizeof(struct arphdr) + | |
56 | 2*ah->ar_hln+sizeof(uint32_t), | |
57 | sizeof(_addr), &_addr); | |
58 | if (ap == NULL) | |
59 | return EBT_NOMATCH; | |
60 | if (FWINV(info->daddr != (*ap & info->dmsk), | |
61 | EBT_ARP_DST_IP)) | |
62 | return EBT_NOMATCH; | |
63 | } | |
64 | } | |
65 | ||
66 | if (info->bitmask & (EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC)) { | |
67 | unsigned char _mac[ETH_ALEN], *mp; | |
68 | uint8_t verdict, i; | |
69 | ||
70 | /* MAC addresses are 6 bytes */ | |
71 | if (ah->ar_hln != ETH_ALEN) | |
72 | return EBT_NOMATCH; | |
73 | if (info->bitmask & EBT_ARP_SRC_MAC) { | |
74 | mp = skb_header_pointer(skb, sizeof(struct arphdr), | |
75 | sizeof(_mac), &_mac); | |
76 | if (mp == NULL) | |
77 | return EBT_NOMATCH; | |
78 | verdict = 0; | |
79 | for (i = 0; i < 6; i++) | |
80 | verdict |= (mp[i] ^ info->smaddr[i]) & | |
81 | info->smmsk[i]; | |
82 | if (FWINV(verdict != 0, EBT_ARP_SRC_MAC)) | |
83 | return EBT_NOMATCH; | |
84 | } | |
85 | ||
86 | if (info->bitmask & EBT_ARP_DST_MAC) { | |
87 | mp = skb_header_pointer(skb, sizeof(struct arphdr) + | |
88 | ah->ar_hln + ah->ar_pln, | |
89 | sizeof(_mac), &_mac); | |
90 | if (mp == NULL) | |
91 | return EBT_NOMATCH; | |
92 | verdict = 0; | |
93 | for (i = 0; i < 6; i++) | |
94 | verdict |= (mp[i] ^ info->dmaddr[i]) & | |
95 | info->dmmsk[i]; | |
96 | if (FWINV(verdict != 0, EBT_ARP_DST_MAC)) | |
97 | return EBT_NOMATCH; | |
98 | } | |
99 | } | |
100 | ||
101 | return EBT_MATCH; | |
102 | } | |
103 | ||
104 | static int ebt_arp_check(const char *tablename, unsigned int hookmask, | |
105 | const struct ebt_entry *e, void *data, unsigned int datalen) | |
106 | { | |
107 | struct ebt_arp_info *info = (struct ebt_arp_info *)data; | |
108 | ||
109 | if (datalen != EBT_ALIGN(sizeof(struct ebt_arp_info))) | |
110 | return -EINVAL; | |
111 | if ((e->ethproto != htons(ETH_P_ARP) && | |
112 | e->ethproto != htons(ETH_P_RARP)) || | |
113 | e->invflags & EBT_IPROTO) | |
114 | return -EINVAL; | |
115 | if (info->bitmask & ~EBT_ARP_MASK || info->invflags & ~EBT_ARP_MASK) | |
116 | return -EINVAL; | |
117 | return 0; | |
118 | } | |
119 | ||
120 | static struct ebt_match filter_arp = | |
121 | { | |
122 | .name = EBT_ARP_MATCH, | |
123 | .match = ebt_filter_arp, | |
124 | .check = ebt_arp_check, | |
125 | .me = THIS_MODULE, | |
126 | }; | |
127 | ||
128 | static int __init init(void) | |
129 | { | |
130 | return ebt_register_match(&filter_arp); | |
131 | } | |
132 | ||
133 | static void __exit fini(void) | |
134 | { | |
135 | ebt_unregister_match(&filter_arp); | |
136 | } | |
137 | ||
138 | module_init(init); | |
139 | module_exit(fini); | |
140 | MODULE_LICENSE("GPL"); |