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> | |
51b0a5d8 PNA |
17 | #include <net/netfilter/ipv4/nf_reject.h> |
18 | #include <net/netfilter/ipv6/nf_reject.h> | |
523b929d PNA |
19 | #include <linux/ip.h> |
20 | #include <net/ip.h> | |
c1207c04 | 21 | #include <net/ip6_checksum.h> |
127917c2 | 22 | #include <linux/netfilter_bridge.h> |
72500bc1 | 23 | #include <linux/netfilter_ipv6.h> |
523b929d PNA |
24 | #include "../br_private.h" |
25 | ||
26 | static void nft_reject_br_push_etherhdr(struct sk_buff *oldskb, | |
27 | struct sk_buff *nskb) | |
28 | { | |
29 | struct ethhdr *eth; | |
30 | ||
31 | eth = (struct ethhdr *)skb_push(nskb, ETH_HLEN); | |
32 | skb_reset_mac_header(nskb); | |
33 | ether_addr_copy(eth->h_source, eth_hdr(oldskb)->h_dest); | |
34 | ether_addr_copy(eth->h_dest, eth_hdr(oldskb)->h_source); | |
35 | eth->h_proto = eth_hdr(oldskb)->h_proto; | |
36 | skb_pull(nskb, ETH_HLEN); | |
37 | } | |
38 | ||
10151d7b PNA |
39 | static int nft_bridge_iphdr_validate(struct sk_buff *skb) |
40 | { | |
41 | struct iphdr *iph; | |
42 | u32 len; | |
43 | ||
44 | if (!pskb_may_pull(skb, sizeof(struct iphdr))) | |
45 | return 0; | |
46 | ||
47 | iph = ip_hdr(skb); | |
48 | if (iph->ihl < 5 || iph->version != 4) | |
49 | return 0; | |
50 | ||
51 | len = ntohs(iph->tot_len); | |
52 | if (skb->len < len) | |
53 | return 0; | |
54 | else if (len < (iph->ihl*4)) | |
55 | return 0; | |
56 | ||
57 | if (!pskb_may_pull(skb, iph->ihl*4)) | |
58 | return 0; | |
59 | ||
60 | return 1; | |
61 | } | |
62 | ||
72500bc1 FW |
63 | /* We cannot use oldskb->dev, it can be either bridge device (NF_BRIDGE INPUT) |
64 | * or the bridge port (NF_BRIDGE PREROUTING). | |
65 | */ | |
29421198 LZ |
66 | static void nft_reject_br_send_v4_tcp_reset(struct net *net, |
67 | struct sk_buff *oldskb, | |
72500bc1 FW |
68 | const struct net_device *dev, |
69 | int hook) | |
523b929d PNA |
70 | { |
71 | struct sk_buff *nskb; | |
72 | struct iphdr *niph; | |
73 | const struct tcphdr *oth; | |
74 | struct tcphdr _oth; | |
75 | ||
68b0faa8 | 76 | if (!nft_bridge_iphdr_validate(oldskb)) |
523b929d PNA |
77 | return; |
78 | ||
79 | oth = nf_reject_ip_tcphdr_get(oldskb, &_oth, hook); | |
80 | if (!oth) | |
81 | return; | |
82 | ||
83 | nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) + | |
84 | LL_MAX_HEADER, GFP_ATOMIC); | |
85 | if (!nskb) | |
86 | return; | |
87 | ||
88 | skb_reserve(nskb, LL_MAX_HEADER); | |
89 | niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP, | |
fa50d974 | 90 | net->ipv4.sysctl_ip_default_ttl); |
523b929d | 91 | nf_reject_ip_tcphdr_put(nskb, oldskb, oth); |
fa50d974 | 92 | niph->ttl = net->ipv4.sysctl_ip_default_ttl; |
523b929d PNA |
93 | niph->tot_len = htons(nskb->len); |
94 | ip_send_check(niph); | |
95 | ||
96 | nft_reject_br_push_etherhdr(oldskb, nskb); | |
97 | ||
37b090e6 | 98 | br_forward(br_port_get_rcu(dev), nskb, false, true); |
523b929d PNA |
99 | } |
100 | ||
29421198 LZ |
101 | static void nft_reject_br_send_v4_unreach(struct net *net, |
102 | struct sk_buff *oldskb, | |
72500bc1 FW |
103 | const struct net_device *dev, |
104 | int hook, u8 code) | |
523b929d PNA |
105 | { |
106 | struct sk_buff *nskb; | |
107 | struct iphdr *niph; | |
108 | struct icmphdr *icmph; | |
109 | unsigned int len; | |
110 | void *payload; | |
111 | __wsum csum; | |
72500bc1 | 112 | u8 proto; |
523b929d | 113 | |
72500bc1 | 114 | if (oldskb->csum_bad || !nft_bridge_iphdr_validate(oldskb)) |
523b929d PNA |
115 | return; |
116 | ||
117 | /* IP header checks: fragment. */ | |
118 | if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET)) | |
119 | return; | |
120 | ||
121 | /* RFC says return as much as we can without exceeding 576 bytes. */ | |
122 | len = min_t(unsigned int, 536, oldskb->len); | |
123 | ||
124 | if (!pskb_may_pull(oldskb, len)) | |
125 | return; | |
126 | ||
a03a8dbe | 127 | if (pskb_trim_rcsum(oldskb, ntohs(ip_hdr(oldskb)->tot_len))) |
72500bc1 FW |
128 | return; |
129 | ||
130 | if (ip_hdr(oldskb)->protocol == IPPROTO_TCP || | |
131 | ip_hdr(oldskb)->protocol == IPPROTO_UDP) | |
132 | proto = ip_hdr(oldskb)->protocol; | |
133 | else | |
134 | proto = 0; | |
135 | ||
136 | if (!skb_csum_unnecessary(oldskb) && | |
137 | nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), proto)) | |
523b929d PNA |
138 | return; |
139 | ||
140 | nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmphdr) + | |
141 | LL_MAX_HEADER + len, GFP_ATOMIC); | |
142 | if (!nskb) | |
143 | return; | |
144 | ||
145 | skb_reserve(nskb, LL_MAX_HEADER); | |
146 | niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_ICMP, | |
fa50d974 | 147 | net->ipv4.sysctl_ip_default_ttl); |
523b929d PNA |
148 | |
149 | skb_reset_transport_header(nskb); | |
150 | icmph = (struct icmphdr *)skb_put(nskb, sizeof(struct icmphdr)); | |
151 | memset(icmph, 0, sizeof(*icmph)); | |
152 | icmph->type = ICMP_DEST_UNREACH; | |
153 | icmph->code = code; | |
154 | ||
155 | payload = skb_put(nskb, len); | |
156 | memcpy(payload, skb_network_header(oldskb), len); | |
157 | ||
158 | csum = csum_partial((void *)icmph, len + sizeof(struct icmphdr), 0); | |
159 | icmph->checksum = csum_fold(csum); | |
160 | ||
161 | niph->tot_len = htons(nskb->len); | |
162 | ip_send_check(niph); | |
163 | ||
164 | nft_reject_br_push_etherhdr(oldskb, nskb); | |
165 | ||
37b090e6 | 166 | br_forward(br_port_get_rcu(dev), nskb, false, true); |
523b929d PNA |
167 | } |
168 | ||
10151d7b PNA |
169 | static int nft_bridge_ip6hdr_validate(struct sk_buff *skb) |
170 | { | |
171 | struct ipv6hdr *hdr; | |
172 | u32 pkt_len; | |
173 | ||
174 | if (!pskb_may_pull(skb, sizeof(struct ipv6hdr))) | |
175 | return 0; | |
176 | ||
177 | hdr = ipv6_hdr(skb); | |
178 | if (hdr->version != 6) | |
179 | return 0; | |
180 | ||
181 | pkt_len = ntohs(hdr->payload_len); | |
182 | if (pkt_len + sizeof(struct ipv6hdr) > skb->len) | |
183 | return 0; | |
184 | ||
185 | return 1; | |
186 | } | |
187 | ||
523b929d | 188 | static void nft_reject_br_send_v6_tcp_reset(struct net *net, |
72500bc1 FW |
189 | struct sk_buff *oldskb, |
190 | const struct net_device *dev, | |
191 | int hook) | |
523b929d PNA |
192 | { |
193 | struct sk_buff *nskb; | |
194 | const struct tcphdr *oth; | |
195 | struct tcphdr _oth; | |
196 | unsigned int otcplen; | |
197 | struct ipv6hdr *nip6h; | |
198 | ||
68b0faa8 | 199 | if (!nft_bridge_ip6hdr_validate(oldskb)) |
523b929d PNA |
200 | return; |
201 | ||
202 | oth = nf_reject_ip6_tcphdr_get(oldskb, &_oth, &otcplen, hook); | |
203 | if (!oth) | |
204 | return; | |
205 | ||
206 | nskb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(struct tcphdr) + | |
207 | LL_MAX_HEADER, GFP_ATOMIC); | |
208 | if (!nskb) | |
209 | return; | |
210 | ||
211 | skb_reserve(nskb, LL_MAX_HEADER); | |
212 | nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP, | |
213 | net->ipv6.devconf_all->hop_limit); | |
214 | nf_reject_ip6_tcphdr_put(nskb, oldskb, oth, otcplen); | |
215 | nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr)); | |
216 | ||
217 | nft_reject_br_push_etherhdr(oldskb, nskb); | |
218 | ||
37b090e6 | 219 | br_forward(br_port_get_rcu(dev), nskb, false, true); |
72500bc1 FW |
220 | } |
221 | ||
222 | static bool reject6_br_csum_ok(struct sk_buff *skb, int hook) | |
223 | { | |
224 | const struct ipv6hdr *ip6h = ipv6_hdr(skb); | |
225 | int thoff; | |
226 | __be16 fo; | |
227 | u8 proto = ip6h->nexthdr; | |
228 | ||
229 | if (skb->csum_bad) | |
230 | return false; | |
231 | ||
232 | if (skb_csum_unnecessary(skb)) | |
233 | return true; | |
234 | ||
235 | if (ip6h->payload_len && | |
236 | pskb_trim_rcsum(skb, ntohs(ip6h->payload_len) + sizeof(*ip6h))) | |
237 | return false; | |
238 | ||
239 | thoff = ipv6_skip_exthdr(skb, ((u8*)(ip6h+1) - skb->data), &proto, &fo); | |
240 | if (thoff < 0 || thoff >= skb->len || (fo & htons(~0x7)) != 0) | |
241 | return false; | |
242 | ||
243 | return nf_ip6_checksum(skb, hook, thoff, proto) == 0; | |
523b929d PNA |
244 | } |
245 | ||
246 | static void nft_reject_br_send_v6_unreach(struct net *net, | |
72500bc1 FW |
247 | struct sk_buff *oldskb, |
248 | const struct net_device *dev, | |
249 | int hook, u8 code) | |
523b929d PNA |
250 | { |
251 | struct sk_buff *nskb; | |
252 | struct ipv6hdr *nip6h; | |
253 | struct icmp6hdr *icmp6h; | |
254 | unsigned int len; | |
255 | void *payload; | |
256 | ||
68b0faa8 | 257 | if (!nft_bridge_ip6hdr_validate(oldskb)) |
523b929d PNA |
258 | return; |
259 | ||
260 | /* Include "As much of invoking packet as possible without the ICMPv6 | |
261 | * packet exceeding the minimum IPv6 MTU" in the ICMP payload. | |
262 | */ | |
263 | len = min_t(unsigned int, 1220, oldskb->len); | |
264 | ||
265 | if (!pskb_may_pull(oldskb, len)) | |
266 | return; | |
267 | ||
72500bc1 FW |
268 | if (!reject6_br_csum_ok(oldskb, hook)) |
269 | return; | |
270 | ||
523b929d PNA |
271 | nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmp6hdr) + |
272 | LL_MAX_HEADER + len, GFP_ATOMIC); | |
273 | if (!nskb) | |
274 | return; | |
275 | ||
276 | skb_reserve(nskb, LL_MAX_HEADER); | |
277 | nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_ICMPV6, | |
278 | net->ipv6.devconf_all->hop_limit); | |
279 | ||
280 | skb_reset_transport_header(nskb); | |
281 | icmp6h = (struct icmp6hdr *)skb_put(nskb, sizeof(struct icmp6hdr)); | |
282 | memset(icmp6h, 0, sizeof(*icmp6h)); | |
283 | icmp6h->icmp6_type = ICMPV6_DEST_UNREACH; | |
284 | icmp6h->icmp6_code = code; | |
285 | ||
286 | payload = skb_put(nskb, len); | |
287 | memcpy(payload, skb_network_header(oldskb), len); | |
288 | nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr)); | |
289 | ||
290 | icmp6h->icmp6_cksum = | |
291 | csum_ipv6_magic(&nip6h->saddr, &nip6h->daddr, | |
292 | nskb->len - sizeof(struct ipv6hdr), | |
293 | IPPROTO_ICMPV6, | |
294 | csum_partial(icmp6h, | |
295 | nskb->len - sizeof(struct ipv6hdr), | |
296 | 0)); | |
297 | ||
298 | nft_reject_br_push_etherhdr(oldskb, nskb); | |
299 | ||
37b090e6 | 300 | br_forward(br_port_get_rcu(dev), nskb, false, true); |
523b929d | 301 | } |
85f5b308 PNA |
302 | |
303 | static void nft_reject_bridge_eval(const struct nft_expr *expr, | |
a55e22e9 PM |
304 | struct nft_regs *regs, |
305 | const struct nft_pktinfo *pkt) | |
85f5b308 | 306 | { |
51b0a5d8 | 307 | struct nft_reject *priv = nft_expr_priv(expr); |
523b929d PNA |
308 | const unsigned char *dest = eth_hdr(pkt->skb)->h_dest; |
309 | ||
310 | if (is_broadcast_ether_addr(dest) || | |
311 | is_multicast_ether_addr(dest)) | |
312 | goto out; | |
51b0a5d8 | 313 | |
85f5b308 PNA |
314 | switch (eth_hdr(pkt->skb)->h_proto) { |
315 | case htons(ETH_P_IP): | |
51b0a5d8 PNA |
316 | switch (priv->type) { |
317 | case NFT_REJECT_ICMP_UNREACH: | |
29421198 LZ |
318 | nft_reject_br_send_v4_unreach(pkt->net, pkt->skb, |
319 | pkt->in, pkt->hook, | |
523b929d | 320 | priv->icmp_code); |
51b0a5d8 PNA |
321 | break; |
322 | case NFT_REJECT_TCP_RST: | |
29421198 LZ |
323 | nft_reject_br_send_v4_tcp_reset(pkt->net, pkt->skb, |
324 | pkt->in, pkt->hook); | |
51b0a5d8 PNA |
325 | break; |
326 | case NFT_REJECT_ICMPX_UNREACH: | |
29421198 LZ |
327 | nft_reject_br_send_v4_unreach(pkt->net, pkt->skb, |
328 | pkt->in, pkt->hook, | |
523b929d | 329 | nft_reject_icmp_code(priv->icmp_code)); |
51b0a5d8 PNA |
330 | break; |
331 | } | |
332 | break; | |
85f5b308 | 333 | case htons(ETH_P_IPV6): |
51b0a5d8 PNA |
334 | switch (priv->type) { |
335 | case NFT_REJECT_ICMP_UNREACH: | |
88182a0e EB |
336 | nft_reject_br_send_v6_unreach(pkt->net, pkt->skb, |
337 | pkt->in, pkt->hook, | |
523b929d | 338 | priv->icmp_code); |
51b0a5d8 PNA |
339 | break; |
340 | case NFT_REJECT_TCP_RST: | |
88182a0e EB |
341 | nft_reject_br_send_v6_tcp_reset(pkt->net, pkt->skb, |
342 | pkt->in, pkt->hook); | |
51b0a5d8 PNA |
343 | break; |
344 | case NFT_REJECT_ICMPX_UNREACH: | |
88182a0e EB |
345 | nft_reject_br_send_v6_unreach(pkt->net, pkt->skb, |
346 | pkt->in, pkt->hook, | |
523b929d | 347 | nft_reject_icmpv6_code(priv->icmp_code)); |
51b0a5d8 PNA |
348 | break; |
349 | } | |
350 | break; | |
85f5b308 PNA |
351 | default: |
352 | /* No explicit way to reject this protocol, drop it. */ | |
85f5b308 PNA |
353 | break; |
354 | } | |
523b929d | 355 | out: |
a55e22e9 | 356 | regs->verdict.code = NF_DROP; |
51b0a5d8 PNA |
357 | } |
358 | ||
75e8d06d PNA |
359 | static int nft_reject_bridge_validate(const struct nft_ctx *ctx, |
360 | const struct nft_expr *expr, | |
361 | const struct nft_data **data) | |
127917c2 | 362 | { |
75e8d06d PNA |
363 | return nft_chain_validate_hooks(ctx->chain, (1 << NF_BR_PRE_ROUTING) | |
364 | (1 << NF_BR_LOCAL_IN)); | |
127917c2 PNA |
365 | } |
366 | ||
51b0a5d8 PNA |
367 | static int nft_reject_bridge_init(const struct nft_ctx *ctx, |
368 | const struct nft_expr *expr, | |
369 | const struct nlattr * const tb[]) | |
370 | { | |
371 | struct nft_reject *priv = nft_expr_priv(expr); | |
127917c2 PNA |
372 | int icmp_code, err; |
373 | ||
75e8d06d | 374 | err = nft_reject_bridge_validate(ctx, expr, NULL); |
127917c2 PNA |
375 | if (err < 0) |
376 | return err; | |
51b0a5d8 PNA |
377 | |
378 | if (tb[NFTA_REJECT_TYPE] == NULL) | |
379 | return -EINVAL; | |
380 | ||
381 | priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE])); | |
382 | switch (priv->type) { | |
383 | case NFT_REJECT_ICMP_UNREACH: | |
384 | case NFT_REJECT_ICMPX_UNREACH: | |
385 | if (tb[NFTA_REJECT_ICMP_CODE] == NULL) | |
386 | return -EINVAL; | |
387 | ||
388 | icmp_code = nla_get_u8(tb[NFTA_REJECT_ICMP_CODE]); | |
389 | if (priv->type == NFT_REJECT_ICMPX_UNREACH && | |
390 | icmp_code > NFT_REJECT_ICMPX_MAX) | |
391 | return -EINVAL; | |
392 | ||
393 | priv->icmp_code = icmp_code; | |
394 | break; | |
395 | case NFT_REJECT_TCP_RST: | |
396 | break; | |
397 | default: | |
398 | return -EINVAL; | |
399 | } | |
400 | return 0; | |
401 | } | |
402 | ||
403 | static int nft_reject_bridge_dump(struct sk_buff *skb, | |
404 | const struct nft_expr *expr) | |
405 | { | |
406 | const struct nft_reject *priv = nft_expr_priv(expr); | |
407 | ||
408 | if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type))) | |
409 | goto nla_put_failure; | |
410 | ||
411 | switch (priv->type) { | |
412 | case NFT_REJECT_ICMP_UNREACH: | |
413 | case NFT_REJECT_ICMPX_UNREACH: | |
414 | if (nla_put_u8(skb, NFTA_REJECT_ICMP_CODE, priv->icmp_code)) | |
415 | goto nla_put_failure; | |
416 | break; | |
c1f86676 DM |
417 | default: |
418 | break; | |
51b0a5d8 PNA |
419 | } |
420 | ||
421 | return 0; | |
422 | ||
423 | nla_put_failure: | |
424 | return -1; | |
85f5b308 PNA |
425 | } |
426 | ||
427 | static struct nft_expr_type nft_reject_bridge_type; | |
428 | static const struct nft_expr_ops nft_reject_bridge_ops = { | |
429 | .type = &nft_reject_bridge_type, | |
430 | .size = NFT_EXPR_SIZE(sizeof(struct nft_reject)), | |
431 | .eval = nft_reject_bridge_eval, | |
51b0a5d8 PNA |
432 | .init = nft_reject_bridge_init, |
433 | .dump = nft_reject_bridge_dump, | |
127917c2 | 434 | .validate = nft_reject_bridge_validate, |
85f5b308 PNA |
435 | }; |
436 | ||
437 | static struct nft_expr_type nft_reject_bridge_type __read_mostly = { | |
438 | .family = NFPROTO_BRIDGE, | |
439 | .name = "reject", | |
440 | .ops = &nft_reject_bridge_ops, | |
441 | .policy = nft_reject_policy, | |
442 | .maxattr = NFTA_REJECT_MAX, | |
443 | .owner = THIS_MODULE, | |
444 | }; | |
445 | ||
446 | static int __init nft_reject_bridge_module_init(void) | |
447 | { | |
448 | return nft_register_expr(&nft_reject_bridge_type); | |
449 | } | |
450 | ||
451 | static void __exit nft_reject_bridge_module_exit(void) | |
452 | { | |
453 | nft_unregister_expr(&nft_reject_bridge_type); | |
454 | } | |
455 | ||
456 | module_init(nft_reject_bridge_module_init); | |
457 | module_exit(nft_reject_bridge_module_exit); | |
458 | ||
459 | MODULE_LICENSE("GPL"); | |
460 | MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>"); | |
461 | MODULE_ALIAS_NFT_AF_EXPR(AF_BRIDGE, "reject"); |