Commit | Line | Data |
---|---|---|
85f5b308 PNA |
1 | /* |
2 | * Copyright (c) 2014 Pablo Neira Ayuso <pablo@netfilter.org> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License version 2 as | |
6 | * published by the Free Software Foundation. | |
7 | */ | |
8 | ||
9 | #include <linux/kernel.h> | |
10 | #include <linux/init.h> | |
11 | #include <linux/module.h> | |
12 | #include <linux/netlink.h> | |
13 | #include <linux/netfilter.h> | |
14 | #include <linux/netfilter/nf_tables.h> | |
15 | #include <net/netfilter/nf_tables.h> | |
16 | #include <net/netfilter/nft_reject.h> | |
68b0faa8 | 17 | #include <net/netfilter/nf_tables_bridge.h> |
51b0a5d8 PNA |
18 | #include <net/netfilter/ipv4/nf_reject.h> |
19 | #include <net/netfilter/ipv6/nf_reject.h> | |
523b929d PNA |
20 | #include <linux/ip.h> |
21 | #include <net/ip.h> | |
c1207c04 | 22 | #include <net/ip6_checksum.h> |
127917c2 | 23 | #include <linux/netfilter_bridge.h> |
72500bc1 | 24 | #include <linux/netfilter_ipv6.h> |
523b929d PNA |
25 | #include "../br_private.h" |
26 | ||
27 | static void nft_reject_br_push_etherhdr(struct sk_buff *oldskb, | |
28 | struct sk_buff *nskb) | |
29 | { | |
30 | struct ethhdr *eth; | |
31 | ||
32 | eth = (struct ethhdr *)skb_push(nskb, ETH_HLEN); | |
33 | skb_reset_mac_header(nskb); | |
34 | ether_addr_copy(eth->h_source, eth_hdr(oldskb)->h_dest); | |
35 | ether_addr_copy(eth->h_dest, eth_hdr(oldskb)->h_source); | |
36 | eth->h_proto = eth_hdr(oldskb)->h_proto; | |
37 | skb_pull(nskb, ETH_HLEN); | |
38 | } | |
39 | ||
72500bc1 FW |
40 | /* We cannot use oldskb->dev, it can be either bridge device (NF_BRIDGE INPUT) |
41 | * or the bridge port (NF_BRIDGE PREROUTING). | |
42 | */ | |
43 | static void nft_reject_br_send_v4_tcp_reset(struct sk_buff *oldskb, | |
44 | const struct net_device *dev, | |
45 | int hook) | |
523b929d PNA |
46 | { |
47 | struct sk_buff *nskb; | |
48 | struct iphdr *niph; | |
49 | const struct tcphdr *oth; | |
50 | struct tcphdr _oth; | |
fa50d974 | 51 | struct net *net = sock_net(oldskb->sk); |
523b929d | 52 | |
68b0faa8 | 53 | if (!nft_bridge_iphdr_validate(oldskb)) |
523b929d PNA |
54 | return; |
55 | ||
56 | oth = nf_reject_ip_tcphdr_get(oldskb, &_oth, hook); | |
57 | if (!oth) | |
58 | return; | |
59 | ||
60 | nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) + | |
61 | LL_MAX_HEADER, GFP_ATOMIC); | |
62 | if (!nskb) | |
63 | return; | |
64 | ||
65 | skb_reserve(nskb, LL_MAX_HEADER); | |
66 | niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP, | |
fa50d974 | 67 | net->ipv4.sysctl_ip_default_ttl); |
523b929d | 68 | nf_reject_ip_tcphdr_put(nskb, oldskb, oth); |
fa50d974 | 69 | niph->ttl = net->ipv4.sysctl_ip_default_ttl; |
523b929d PNA |
70 | niph->tot_len = htons(nskb->len); |
71 | ip_send_check(niph); | |
72 | ||
73 | nft_reject_br_push_etherhdr(oldskb, nskb); | |
74 | ||
72500bc1 | 75 | br_deliver(br_port_get_rcu(dev), nskb); |
523b929d PNA |
76 | } |
77 | ||
72500bc1 FW |
78 | static void nft_reject_br_send_v4_unreach(struct sk_buff *oldskb, |
79 | const struct net_device *dev, | |
80 | int hook, u8 code) | |
523b929d PNA |
81 | { |
82 | struct sk_buff *nskb; | |
83 | struct iphdr *niph; | |
84 | struct icmphdr *icmph; | |
85 | unsigned int len; | |
86 | void *payload; | |
87 | __wsum csum; | |
72500bc1 | 88 | u8 proto; |
fa50d974 | 89 | struct net *net = sock_net(oldskb->sk); |
523b929d | 90 | |
72500bc1 | 91 | if (oldskb->csum_bad || !nft_bridge_iphdr_validate(oldskb)) |
523b929d PNA |
92 | return; |
93 | ||
94 | /* IP header checks: fragment. */ | |
95 | if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET)) | |
96 | return; | |
97 | ||
98 | /* RFC says return as much as we can without exceeding 576 bytes. */ | |
99 | len = min_t(unsigned int, 536, oldskb->len); | |
100 | ||
101 | if (!pskb_may_pull(oldskb, len)) | |
102 | return; | |
103 | ||
a03a8dbe | 104 | if (pskb_trim_rcsum(oldskb, ntohs(ip_hdr(oldskb)->tot_len))) |
72500bc1 FW |
105 | return; |
106 | ||
107 | if (ip_hdr(oldskb)->protocol == IPPROTO_TCP || | |
108 | ip_hdr(oldskb)->protocol == IPPROTO_UDP) | |
109 | proto = ip_hdr(oldskb)->protocol; | |
110 | else | |
111 | proto = 0; | |
112 | ||
113 | if (!skb_csum_unnecessary(oldskb) && | |
114 | nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), proto)) | |
523b929d PNA |
115 | return; |
116 | ||
117 | nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmphdr) + | |
118 | LL_MAX_HEADER + len, GFP_ATOMIC); | |
119 | if (!nskb) | |
120 | return; | |
121 | ||
122 | skb_reserve(nskb, LL_MAX_HEADER); | |
123 | niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_ICMP, | |
fa50d974 | 124 | net->ipv4.sysctl_ip_default_ttl); |
523b929d PNA |
125 | |
126 | skb_reset_transport_header(nskb); | |
127 | icmph = (struct icmphdr *)skb_put(nskb, sizeof(struct icmphdr)); | |
128 | memset(icmph, 0, sizeof(*icmph)); | |
129 | icmph->type = ICMP_DEST_UNREACH; | |
130 | icmph->code = code; | |
131 | ||
132 | payload = skb_put(nskb, len); | |
133 | memcpy(payload, skb_network_header(oldskb), len); | |
134 | ||
135 | csum = csum_partial((void *)icmph, len + sizeof(struct icmphdr), 0); | |
136 | icmph->checksum = csum_fold(csum); | |
137 | ||
138 | niph->tot_len = htons(nskb->len); | |
139 | ip_send_check(niph); | |
140 | ||
141 | nft_reject_br_push_etherhdr(oldskb, nskb); | |
142 | ||
72500bc1 | 143 | br_deliver(br_port_get_rcu(dev), nskb); |
523b929d PNA |
144 | } |
145 | ||
523b929d | 146 | static void nft_reject_br_send_v6_tcp_reset(struct net *net, |
72500bc1 FW |
147 | struct sk_buff *oldskb, |
148 | const struct net_device *dev, | |
149 | int hook) | |
523b929d PNA |
150 | { |
151 | struct sk_buff *nskb; | |
152 | const struct tcphdr *oth; | |
153 | struct tcphdr _oth; | |
154 | unsigned int otcplen; | |
155 | struct ipv6hdr *nip6h; | |
156 | ||
68b0faa8 | 157 | if (!nft_bridge_ip6hdr_validate(oldskb)) |
523b929d PNA |
158 | return; |
159 | ||
160 | oth = nf_reject_ip6_tcphdr_get(oldskb, &_oth, &otcplen, hook); | |
161 | if (!oth) | |
162 | return; | |
163 | ||
164 | nskb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(struct tcphdr) + | |
165 | LL_MAX_HEADER, GFP_ATOMIC); | |
166 | if (!nskb) | |
167 | return; | |
168 | ||
169 | skb_reserve(nskb, LL_MAX_HEADER); | |
170 | nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP, | |
171 | net->ipv6.devconf_all->hop_limit); | |
172 | nf_reject_ip6_tcphdr_put(nskb, oldskb, oth, otcplen); | |
173 | nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr)); | |
174 | ||
175 | nft_reject_br_push_etherhdr(oldskb, nskb); | |
176 | ||
72500bc1 FW |
177 | br_deliver(br_port_get_rcu(dev), nskb); |
178 | } | |
179 | ||
180 | static bool reject6_br_csum_ok(struct sk_buff *skb, int hook) | |
181 | { | |
182 | const struct ipv6hdr *ip6h = ipv6_hdr(skb); | |
183 | int thoff; | |
184 | __be16 fo; | |
185 | u8 proto = ip6h->nexthdr; | |
186 | ||
187 | if (skb->csum_bad) | |
188 | return false; | |
189 | ||
190 | if (skb_csum_unnecessary(skb)) | |
191 | return true; | |
192 | ||
193 | if (ip6h->payload_len && | |
194 | pskb_trim_rcsum(skb, ntohs(ip6h->payload_len) + sizeof(*ip6h))) | |
195 | return false; | |
196 | ||
197 | thoff = ipv6_skip_exthdr(skb, ((u8*)(ip6h+1) - skb->data), &proto, &fo); | |
198 | if (thoff < 0 || thoff >= skb->len || (fo & htons(~0x7)) != 0) | |
199 | return false; | |
200 | ||
201 | return nf_ip6_checksum(skb, hook, thoff, proto) == 0; | |
523b929d PNA |
202 | } |
203 | ||
204 | static void nft_reject_br_send_v6_unreach(struct net *net, | |
72500bc1 FW |
205 | struct sk_buff *oldskb, |
206 | const struct net_device *dev, | |
207 | int hook, u8 code) | |
523b929d PNA |
208 | { |
209 | struct sk_buff *nskb; | |
210 | struct ipv6hdr *nip6h; | |
211 | struct icmp6hdr *icmp6h; | |
212 | unsigned int len; | |
213 | void *payload; | |
214 | ||
68b0faa8 | 215 | if (!nft_bridge_ip6hdr_validate(oldskb)) |
523b929d PNA |
216 | return; |
217 | ||
218 | /* Include "As much of invoking packet as possible without the ICMPv6 | |
219 | * packet exceeding the minimum IPv6 MTU" in the ICMP payload. | |
220 | */ | |
221 | len = min_t(unsigned int, 1220, oldskb->len); | |
222 | ||
223 | if (!pskb_may_pull(oldskb, len)) | |
224 | return; | |
225 | ||
72500bc1 FW |
226 | if (!reject6_br_csum_ok(oldskb, hook)) |
227 | return; | |
228 | ||
523b929d PNA |
229 | nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmp6hdr) + |
230 | LL_MAX_HEADER + len, GFP_ATOMIC); | |
231 | if (!nskb) | |
232 | return; | |
233 | ||
234 | skb_reserve(nskb, LL_MAX_HEADER); | |
235 | nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_ICMPV6, | |
236 | net->ipv6.devconf_all->hop_limit); | |
237 | ||
238 | skb_reset_transport_header(nskb); | |
239 | icmp6h = (struct icmp6hdr *)skb_put(nskb, sizeof(struct icmp6hdr)); | |
240 | memset(icmp6h, 0, sizeof(*icmp6h)); | |
241 | icmp6h->icmp6_type = ICMPV6_DEST_UNREACH; | |
242 | icmp6h->icmp6_code = code; | |
243 | ||
244 | payload = skb_put(nskb, len); | |
245 | memcpy(payload, skb_network_header(oldskb), len); | |
246 | nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr)); | |
247 | ||
248 | icmp6h->icmp6_cksum = | |
249 | csum_ipv6_magic(&nip6h->saddr, &nip6h->daddr, | |
250 | nskb->len - sizeof(struct ipv6hdr), | |
251 | IPPROTO_ICMPV6, | |
252 | csum_partial(icmp6h, | |
253 | nskb->len - sizeof(struct ipv6hdr), | |
254 | 0)); | |
255 | ||
256 | nft_reject_br_push_etherhdr(oldskb, nskb); | |
257 | ||
72500bc1 | 258 | br_deliver(br_port_get_rcu(dev), nskb); |
523b929d | 259 | } |
85f5b308 PNA |
260 | |
261 | static void nft_reject_bridge_eval(const struct nft_expr *expr, | |
a55e22e9 PM |
262 | struct nft_regs *regs, |
263 | const struct nft_pktinfo *pkt) | |
85f5b308 | 264 | { |
51b0a5d8 | 265 | struct nft_reject *priv = nft_expr_priv(expr); |
523b929d PNA |
266 | const unsigned char *dest = eth_hdr(pkt->skb)->h_dest; |
267 | ||
268 | if (is_broadcast_ether_addr(dest) || | |
269 | is_multicast_ether_addr(dest)) | |
270 | goto out; | |
51b0a5d8 | 271 | |
85f5b308 PNA |
272 | switch (eth_hdr(pkt->skb)->h_proto) { |
273 | case htons(ETH_P_IP): | |
51b0a5d8 PNA |
274 | switch (priv->type) { |
275 | case NFT_REJECT_ICMP_UNREACH: | |
72500bc1 | 276 | nft_reject_br_send_v4_unreach(pkt->skb, pkt->in, |
6aa187f2 | 277 | pkt->hook, |
523b929d | 278 | priv->icmp_code); |
51b0a5d8 PNA |
279 | break; |
280 | case NFT_REJECT_TCP_RST: | |
72500bc1 | 281 | nft_reject_br_send_v4_tcp_reset(pkt->skb, pkt->in, |
6aa187f2 | 282 | pkt->hook); |
51b0a5d8 PNA |
283 | break; |
284 | case NFT_REJECT_ICMPX_UNREACH: | |
72500bc1 | 285 | nft_reject_br_send_v4_unreach(pkt->skb, pkt->in, |
6aa187f2 | 286 | pkt->hook, |
523b929d | 287 | nft_reject_icmp_code(priv->icmp_code)); |
51b0a5d8 PNA |
288 | break; |
289 | } | |
290 | break; | |
85f5b308 | 291 | case htons(ETH_P_IPV6): |
51b0a5d8 PNA |
292 | switch (priv->type) { |
293 | case NFT_REJECT_ICMP_UNREACH: | |
88182a0e EB |
294 | nft_reject_br_send_v6_unreach(pkt->net, pkt->skb, |
295 | pkt->in, pkt->hook, | |
523b929d | 296 | priv->icmp_code); |
51b0a5d8 PNA |
297 | break; |
298 | case NFT_REJECT_TCP_RST: | |
88182a0e EB |
299 | nft_reject_br_send_v6_tcp_reset(pkt->net, pkt->skb, |
300 | pkt->in, pkt->hook); | |
51b0a5d8 PNA |
301 | break; |
302 | case NFT_REJECT_ICMPX_UNREACH: | |
88182a0e EB |
303 | nft_reject_br_send_v6_unreach(pkt->net, pkt->skb, |
304 | pkt->in, pkt->hook, | |
523b929d | 305 | nft_reject_icmpv6_code(priv->icmp_code)); |
51b0a5d8 PNA |
306 | break; |
307 | } | |
308 | break; | |
85f5b308 PNA |
309 | default: |
310 | /* No explicit way to reject this protocol, drop it. */ | |
85f5b308 PNA |
311 | break; |
312 | } | |
523b929d | 313 | out: |
a55e22e9 | 314 | regs->verdict.code = NF_DROP; |
51b0a5d8 PNA |
315 | } |
316 | ||
75e8d06d PNA |
317 | static int nft_reject_bridge_validate(const struct nft_ctx *ctx, |
318 | const struct nft_expr *expr, | |
319 | const struct nft_data **data) | |
127917c2 | 320 | { |
75e8d06d PNA |
321 | return nft_chain_validate_hooks(ctx->chain, (1 << NF_BR_PRE_ROUTING) | |
322 | (1 << NF_BR_LOCAL_IN)); | |
127917c2 PNA |
323 | } |
324 | ||
51b0a5d8 PNA |
325 | static int nft_reject_bridge_init(const struct nft_ctx *ctx, |
326 | const struct nft_expr *expr, | |
327 | const struct nlattr * const tb[]) | |
328 | { | |
329 | struct nft_reject *priv = nft_expr_priv(expr); | |
127917c2 PNA |
330 | int icmp_code, err; |
331 | ||
75e8d06d | 332 | err = nft_reject_bridge_validate(ctx, expr, NULL); |
127917c2 PNA |
333 | if (err < 0) |
334 | return err; | |
51b0a5d8 PNA |
335 | |
336 | if (tb[NFTA_REJECT_TYPE] == NULL) | |
337 | return -EINVAL; | |
338 | ||
339 | priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE])); | |
340 | switch (priv->type) { | |
341 | case NFT_REJECT_ICMP_UNREACH: | |
342 | case NFT_REJECT_ICMPX_UNREACH: | |
343 | if (tb[NFTA_REJECT_ICMP_CODE] == NULL) | |
344 | return -EINVAL; | |
345 | ||
346 | icmp_code = nla_get_u8(tb[NFTA_REJECT_ICMP_CODE]); | |
347 | if (priv->type == NFT_REJECT_ICMPX_UNREACH && | |
348 | icmp_code > NFT_REJECT_ICMPX_MAX) | |
349 | return -EINVAL; | |
350 | ||
351 | priv->icmp_code = icmp_code; | |
352 | break; | |
353 | case NFT_REJECT_TCP_RST: | |
354 | break; | |
355 | default: | |
356 | return -EINVAL; | |
357 | } | |
358 | return 0; | |
359 | } | |
360 | ||
361 | static int nft_reject_bridge_dump(struct sk_buff *skb, | |
362 | const struct nft_expr *expr) | |
363 | { | |
364 | const struct nft_reject *priv = nft_expr_priv(expr); | |
365 | ||
366 | if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type))) | |
367 | goto nla_put_failure; | |
368 | ||
369 | switch (priv->type) { | |
370 | case NFT_REJECT_ICMP_UNREACH: | |
371 | case NFT_REJECT_ICMPX_UNREACH: | |
372 | if (nla_put_u8(skb, NFTA_REJECT_ICMP_CODE, priv->icmp_code)) | |
373 | goto nla_put_failure; | |
374 | break; | |
c1f86676 DM |
375 | default: |
376 | break; | |
51b0a5d8 PNA |
377 | } |
378 | ||
379 | return 0; | |
380 | ||
381 | nla_put_failure: | |
382 | return -1; | |
85f5b308 PNA |
383 | } |
384 | ||
385 | static struct nft_expr_type nft_reject_bridge_type; | |
386 | static const struct nft_expr_ops nft_reject_bridge_ops = { | |
387 | .type = &nft_reject_bridge_type, | |
388 | .size = NFT_EXPR_SIZE(sizeof(struct nft_reject)), | |
389 | .eval = nft_reject_bridge_eval, | |
51b0a5d8 PNA |
390 | .init = nft_reject_bridge_init, |
391 | .dump = nft_reject_bridge_dump, | |
127917c2 | 392 | .validate = nft_reject_bridge_validate, |
85f5b308 PNA |
393 | }; |
394 | ||
395 | static struct nft_expr_type nft_reject_bridge_type __read_mostly = { | |
396 | .family = NFPROTO_BRIDGE, | |
397 | .name = "reject", | |
398 | .ops = &nft_reject_bridge_ops, | |
399 | .policy = nft_reject_policy, | |
400 | .maxattr = NFTA_REJECT_MAX, | |
401 | .owner = THIS_MODULE, | |
402 | }; | |
403 | ||
404 | static int __init nft_reject_bridge_module_init(void) | |
405 | { | |
406 | return nft_register_expr(&nft_reject_bridge_type); | |
407 | } | |
408 | ||
409 | static void __exit nft_reject_bridge_module_exit(void) | |
410 | { | |
411 | nft_unregister_expr(&nft_reject_bridge_type); | |
412 | } | |
413 | ||
414 | module_init(nft_reject_bridge_module_init); | |
415 | module_exit(nft_reject_bridge_module_exit); | |
416 | ||
417 | MODULE_LICENSE("GPL"); | |
418 | MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>"); | |
419 | MODULE_ALIAS_NFT_AF_EXPR(AF_BRIDGE, "reject"); |