1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * ebt_stp |
4 | * |
5 | * Authors: |
6 | * Bart De Schuymer <bdschuym@pandora.be> |
7 | * Stephen Hemminger <shemminger@osdl.org> |
8 | * |
9 | * July, 2003 |
10 | */ |
11 | #include <linux/etherdevice.h> |
12 | #include <linux/module.h> |
13 | #include <linux/netfilter/x_tables.h> |
14 | #include <linux/netfilter_bridge/ebtables.h> |
15 | #include <linux/netfilter_bridge/ebt_stp.h> |
16 | |
17 | #define BPDU_TYPE_CONFIG 0 |
18 | |
19 | struct { |
20 | u8 ; |
21 | u8 ; |
22 | u8 ; |
23 | u8 ; |
24 | u8 ; |
25 | u8 ; |
26 | }; |
27 | |
28 | struct stp_config_pdu { |
29 | u8 flags; |
30 | u8 root[8]; |
31 | u8 root_cost[4]; |
32 | u8 sender[8]; |
33 | u8 port[2]; |
34 | u8 msg_age[2]; |
35 | u8 max_age[2]; |
36 | u8 hello_time[2]; |
37 | u8 forward_delay[2]; |
38 | }; |
39 | |
40 | #define NR16(p) (p[0] << 8 | p[1]) |
41 | #define NR32(p) ((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]) |
42 | |
43 | static bool ebt_filter_config(const struct ebt_stp_info *info, |
44 | const struct stp_config_pdu *stpc) |
45 | { |
46 | const struct ebt_stp_config_info *c; |
47 | u16 v16; |
48 | u32 v32; |
49 | |
50 | c = &info->config; |
51 | if ((info->bitmask & EBT_STP_FLAGS) && |
52 | NF_INVF(info, EBT_STP_FLAGS, c->flags != stpc->flags)) |
53 | return false; |
54 | if (info->bitmask & EBT_STP_ROOTPRIO) { |
55 | v16 = NR16(stpc->root); |
56 | if (NF_INVF(info, EBT_STP_ROOTPRIO, |
57 | v16 < c->root_priol || v16 > c->root_priou)) |
58 | return false; |
59 | } |
60 | if (info->bitmask & EBT_STP_ROOTADDR) { |
61 | if (NF_INVF(info, EBT_STP_ROOTADDR, |
62 | !ether_addr_equal_masked(&stpc->root[2], |
63 | c->root_addr, |
64 | c->root_addrmsk))) |
65 | return false; |
66 | } |
67 | if (info->bitmask & EBT_STP_ROOTCOST) { |
68 | v32 = NR32(stpc->root_cost); |
69 | if (NF_INVF(info, EBT_STP_ROOTCOST, |
70 | v32 < c->root_costl || v32 > c->root_costu)) |
71 | return false; |
72 | } |
73 | if (info->bitmask & EBT_STP_SENDERPRIO) { |
74 | v16 = NR16(stpc->sender); |
75 | if (NF_INVF(info, EBT_STP_SENDERPRIO, |
76 | v16 < c->sender_priol || v16 > c->sender_priou)) |
77 | return false; |
78 | } |
79 | if (info->bitmask & EBT_STP_SENDERADDR) { |
80 | if (NF_INVF(info, EBT_STP_SENDERADDR, |
81 | !ether_addr_equal_masked(&stpc->sender[2], |
82 | c->sender_addr, |
83 | c->sender_addrmsk))) |
84 | return false; |
85 | } |
86 | if (info->bitmask & EBT_STP_PORT) { |
87 | v16 = NR16(stpc->port); |
88 | if (NF_INVF(info, EBT_STP_PORT, |
89 | v16 < c->portl || v16 > c->portu)) |
90 | return false; |
91 | } |
92 | if (info->bitmask & EBT_STP_MSGAGE) { |
93 | v16 = NR16(stpc->msg_age); |
94 | if (NF_INVF(info, EBT_STP_MSGAGE, |
95 | v16 < c->msg_agel || v16 > c->msg_ageu)) |
96 | return false; |
97 | } |
98 | if (info->bitmask & EBT_STP_MAXAGE) { |
99 | v16 = NR16(stpc->max_age); |
100 | if (NF_INVF(info, EBT_STP_MAXAGE, |
101 | v16 < c->max_agel || v16 > c->max_ageu)) |
102 | return false; |
103 | } |
104 | if (info->bitmask & EBT_STP_HELLOTIME) { |
105 | v16 = NR16(stpc->hello_time); |
106 | if (NF_INVF(info, EBT_STP_HELLOTIME, |
107 | v16 < c->hello_timel || v16 > c->hello_timeu)) |
108 | return false; |
109 | } |
110 | if (info->bitmask & EBT_STP_FWDD) { |
111 | v16 = NR16(stpc->forward_delay); |
112 | if (NF_INVF(info, EBT_STP_FWDD, |
113 | v16 < c->forward_delayl || v16 > c->forward_delayu)) |
114 | return false; |
115 | } |
116 | return true; |
117 | } |
118 | |
119 | static bool |
120 | ebt_stp_mt(const struct sk_buff *skb, struct xt_action_param *par) |
121 | { |
122 | const struct ebt_stp_info *info = par->matchinfo; |
123 | const struct stp_header *sp; |
124 | struct stp_header _stph; |
125 | const u8 [6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00}; |
126 | |
127 | sp = skb_header_pointer(skb, offset: 0, len: sizeof(_stph), buffer: &_stph); |
128 | if (sp == NULL) |
129 | return false; |
130 | |
131 | /* The stp code only considers these */ |
132 | if (memcmp(p: sp, q: header, size: sizeof(header))) |
133 | return false; |
134 | |
135 | if ((info->bitmask & EBT_STP_TYPE) && |
136 | NF_INVF(info, EBT_STP_TYPE, info->type != sp->type)) |
137 | return false; |
138 | |
139 | if (sp->type == BPDU_TYPE_CONFIG && |
140 | info->bitmask & EBT_STP_CONFIG_MASK) { |
141 | const struct stp_config_pdu *st; |
142 | struct stp_config_pdu _stpc; |
143 | |
144 | st = skb_header_pointer(skb, offset: sizeof(_stph), |
145 | len: sizeof(_stpc), buffer: &_stpc); |
146 | if (st == NULL) |
147 | return false; |
148 | return ebt_filter_config(info, stpc: st); |
149 | } |
150 | return true; |
151 | } |
152 | |
153 | static int ebt_stp_mt_check(const struct xt_mtchk_param *par) |
154 | { |
155 | const struct ebt_stp_info *info = par->matchinfo; |
156 | const struct ebt_entry *e = par->entryinfo; |
157 | |
158 | if (info->bitmask & ~EBT_STP_MASK || info->invflags & ~EBT_STP_MASK || |
159 | !(info->bitmask & EBT_STP_MASK)) |
160 | return -EINVAL; |
161 | /* Make sure the match only receives stp frames */ |
162 | if (!par->nft_compat && |
163 | (!ether_addr_equal(addr1: e->destmac, eth_stp_addr) || |
164 | !(e->bitmask & EBT_DESTMAC) || |
165 | !is_broadcast_ether_addr(addr: e->destmsk))) |
166 | return -EINVAL; |
167 | |
168 | return 0; |
169 | } |
170 | |
171 | static struct xt_match ebt_stp_mt_reg __read_mostly = { |
172 | .name = "stp" , |
173 | .revision = 0, |
174 | .family = NFPROTO_BRIDGE, |
175 | .match = ebt_stp_mt, |
176 | .checkentry = ebt_stp_mt_check, |
177 | .matchsize = sizeof(struct ebt_stp_info), |
178 | .me = THIS_MODULE, |
179 | }; |
180 | |
181 | static int __init ebt_stp_init(void) |
182 | { |
183 | return xt_register_match(target: &ebt_stp_mt_reg); |
184 | } |
185 | |
186 | static void __exit ebt_stp_fini(void) |
187 | { |
188 | xt_unregister_match(target: &ebt_stp_mt_reg); |
189 | } |
190 | |
191 | module_init(ebt_stp_init); |
192 | module_exit(ebt_stp_fini); |
193 | MODULE_DESCRIPTION("Ebtables: Spanning Tree Protocol packet match" ); |
194 | MODULE_LICENSE("GPL" ); |
195 | |