2 * Copyright (c) 2014 Pablo Neira Ayuso <pablo@netfilter.org>
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.
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>
17 #include <net/netfilter/ipv4/nf_reject.h>
18 #include <net/netfilter/ipv6/nf_reject.h>
21 #include <net/ip6_checksum.h>
22 #include <linux/netfilter_bridge.h>
23 #include <linux/netfilter_ipv6.h>
24 #include "../br_private.h"
26 static void nft_reject_br_push_etherhdr(struct sk_buff *oldskb,
31 eth = 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);
39 static int nft_bridge_iphdr_validate(struct sk_buff *skb)
44 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
48 if (iph->ihl < 5 || iph->version != 4)
51 len = ntohs(iph->tot_len);
54 else if (len < (iph->ihl*4))
57 if (!pskb_may_pull(skb, iph->ihl*4))
63 /* We cannot use oldskb->dev, it can be either bridge device (NF_BRIDGE INPUT)
64 * or the bridge port (NF_BRIDGE PREROUTING).
66 static void nft_reject_br_send_v4_tcp_reset(struct net *net,
67 struct sk_buff *oldskb,
68 const struct net_device *dev,
73 const struct tcphdr *oth;
76 if (!nft_bridge_iphdr_validate(oldskb))
79 oth = nf_reject_ip_tcphdr_get(oldskb, &_oth, hook);
83 nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) +
84 LL_MAX_HEADER, GFP_ATOMIC);
88 skb_reserve(nskb, LL_MAX_HEADER);
89 niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP,
90 net->ipv4.sysctl_ip_default_ttl);
91 nf_reject_ip_tcphdr_put(nskb, oldskb, oth);
92 niph->tot_len = htons(nskb->len);
95 nft_reject_br_push_etherhdr(oldskb, nskb);
97 br_forward(br_port_get_rcu(dev), nskb, false, true);
100 static void nft_reject_br_send_v4_unreach(struct net *net,
101 struct sk_buff *oldskb,
102 const struct net_device *dev,
105 struct sk_buff *nskb;
107 struct icmphdr *icmph;
112 if (!nft_bridge_iphdr_validate(oldskb))
115 /* IP header checks: fragment. */
116 if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))
119 /* RFC says return as much as we can without exceeding 576 bytes. */
120 len = min_t(unsigned int, 536, oldskb->len);
122 if (!pskb_may_pull(oldskb, len))
125 if (pskb_trim_rcsum(oldskb, ntohs(ip_hdr(oldskb)->tot_len)))
128 proto = ip_hdr(oldskb)->protocol;
130 if (!skb_csum_unnecessary(oldskb) &&
131 nf_reject_verify_csum(proto) &&
132 nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), proto))
135 nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmphdr) +
136 LL_MAX_HEADER + len, GFP_ATOMIC);
140 skb_reserve(nskb, LL_MAX_HEADER);
141 niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_ICMP,
142 net->ipv4.sysctl_ip_default_ttl);
144 skb_reset_transport_header(nskb);
145 icmph = skb_put_zero(nskb, sizeof(struct icmphdr));
146 icmph->type = ICMP_DEST_UNREACH;
149 skb_put_data(nskb, skb_network_header(oldskb), len);
151 csum = csum_partial((void *)icmph, len + sizeof(struct icmphdr), 0);
152 icmph->checksum = csum_fold(csum);
154 niph->tot_len = htons(nskb->len);
157 nft_reject_br_push_etherhdr(oldskb, nskb);
159 br_forward(br_port_get_rcu(dev), nskb, false, true);
162 static int nft_bridge_ip6hdr_validate(struct sk_buff *skb)
167 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
171 if (hdr->version != 6)
174 pkt_len = ntohs(hdr->payload_len);
175 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
181 static void nft_reject_br_send_v6_tcp_reset(struct net *net,
182 struct sk_buff *oldskb,
183 const struct net_device *dev,
186 struct sk_buff *nskb;
187 const struct tcphdr *oth;
189 unsigned int otcplen;
190 struct ipv6hdr *nip6h;
192 if (!nft_bridge_ip6hdr_validate(oldskb))
195 oth = nf_reject_ip6_tcphdr_get(oldskb, &_oth, &otcplen, hook);
199 nskb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(struct tcphdr) +
200 LL_MAX_HEADER, GFP_ATOMIC);
204 skb_reserve(nskb, LL_MAX_HEADER);
205 nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP,
206 net->ipv6.devconf_all->hop_limit);
207 nf_reject_ip6_tcphdr_put(nskb, oldskb, oth, otcplen);
208 nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr));
210 nft_reject_br_push_etherhdr(oldskb, nskb);
212 br_forward(br_port_get_rcu(dev), nskb, false, true);
215 static bool reject6_br_csum_ok(struct sk_buff *skb, int hook)
217 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
220 u8 proto = ip6h->nexthdr;
222 if (skb_csum_unnecessary(skb))
225 if (ip6h->payload_len &&
226 pskb_trim_rcsum(skb, ntohs(ip6h->payload_len) + sizeof(*ip6h)))
229 ip6h = ipv6_hdr(skb);
230 thoff = ipv6_skip_exthdr(skb, ((u8*)(ip6h+1) - skb->data), &proto, &fo);
231 if (thoff < 0 || thoff >= skb->len || (fo & htons(~0x7)) != 0)
234 if (!nf_reject_verify_csum(proto))
237 return nf_ip6_checksum(skb, hook, thoff, proto) == 0;
240 static void nft_reject_br_send_v6_unreach(struct net *net,
241 struct sk_buff *oldskb,
242 const struct net_device *dev,
245 struct sk_buff *nskb;
246 struct ipv6hdr *nip6h;
247 struct icmp6hdr *icmp6h;
250 if (!nft_bridge_ip6hdr_validate(oldskb))
253 /* Include "As much of invoking packet as possible without the ICMPv6
254 * packet exceeding the minimum IPv6 MTU" in the ICMP payload.
256 len = min_t(unsigned int, 1220, oldskb->len);
258 if (!pskb_may_pull(oldskb, len))
261 if (!reject6_br_csum_ok(oldskb, hook))
264 nskb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(struct icmp6hdr) +
265 LL_MAX_HEADER + len, GFP_ATOMIC);
269 skb_reserve(nskb, LL_MAX_HEADER);
270 nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_ICMPV6,
271 net->ipv6.devconf_all->hop_limit);
273 skb_reset_transport_header(nskb);
274 icmp6h = skb_put_zero(nskb, sizeof(struct icmp6hdr));
275 icmp6h->icmp6_type = ICMPV6_DEST_UNREACH;
276 icmp6h->icmp6_code = code;
278 skb_put_data(nskb, skb_network_header(oldskb), len);
279 nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr));
281 icmp6h->icmp6_cksum =
282 csum_ipv6_magic(&nip6h->saddr, &nip6h->daddr,
283 nskb->len - sizeof(struct ipv6hdr),
286 nskb->len - sizeof(struct ipv6hdr),
289 nft_reject_br_push_etherhdr(oldskb, nskb);
291 br_forward(br_port_get_rcu(dev), nskb, false, true);
294 static void nft_reject_bridge_eval(const struct nft_expr *expr,
295 struct nft_regs *regs,
296 const struct nft_pktinfo *pkt)
298 struct nft_reject *priv = nft_expr_priv(expr);
299 const unsigned char *dest = eth_hdr(pkt->skb)->h_dest;
301 if (is_broadcast_ether_addr(dest) ||
302 is_multicast_ether_addr(dest))
305 switch (eth_hdr(pkt->skb)->h_proto) {
306 case htons(ETH_P_IP):
307 switch (priv->type) {
308 case NFT_REJECT_ICMP_UNREACH:
309 nft_reject_br_send_v4_unreach(nft_net(pkt), pkt->skb,
314 case NFT_REJECT_TCP_RST:
315 nft_reject_br_send_v4_tcp_reset(nft_net(pkt), pkt->skb,
319 case NFT_REJECT_ICMPX_UNREACH:
320 nft_reject_br_send_v4_unreach(nft_net(pkt), pkt->skb,
323 nft_reject_icmp_code(priv->icmp_code));
327 case htons(ETH_P_IPV6):
328 switch (priv->type) {
329 case NFT_REJECT_ICMP_UNREACH:
330 nft_reject_br_send_v6_unreach(nft_net(pkt), pkt->skb,
335 case NFT_REJECT_TCP_RST:
336 nft_reject_br_send_v6_tcp_reset(nft_net(pkt), pkt->skb,
340 case NFT_REJECT_ICMPX_UNREACH:
341 nft_reject_br_send_v6_unreach(nft_net(pkt), pkt->skb,
344 nft_reject_icmpv6_code(priv->icmp_code));
349 /* No explicit way to reject this protocol, drop it. */
353 regs->verdict.code = NF_DROP;
356 static int nft_reject_bridge_validate(const struct nft_ctx *ctx,
357 const struct nft_expr *expr,
358 const struct nft_data **data)
360 return nft_chain_validate_hooks(ctx->chain, (1 << NF_BR_PRE_ROUTING) |
361 (1 << NF_BR_LOCAL_IN));
364 static int nft_reject_bridge_init(const struct nft_ctx *ctx,
365 const struct nft_expr *expr,
366 const struct nlattr * const tb[])
368 struct nft_reject *priv = nft_expr_priv(expr);
371 if (tb[NFTA_REJECT_TYPE] == NULL)
374 priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE]));
375 switch (priv->type) {
376 case NFT_REJECT_ICMP_UNREACH:
377 case NFT_REJECT_ICMPX_UNREACH:
378 if (tb[NFTA_REJECT_ICMP_CODE] == NULL)
381 icmp_code = nla_get_u8(tb[NFTA_REJECT_ICMP_CODE]);
382 if (priv->type == NFT_REJECT_ICMPX_UNREACH &&
383 icmp_code > NFT_REJECT_ICMPX_MAX)
386 priv->icmp_code = icmp_code;
388 case NFT_REJECT_TCP_RST:
396 static int nft_reject_bridge_dump(struct sk_buff *skb,
397 const struct nft_expr *expr)
399 const struct nft_reject *priv = nft_expr_priv(expr);
401 if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type)))
402 goto nla_put_failure;
404 switch (priv->type) {
405 case NFT_REJECT_ICMP_UNREACH:
406 case NFT_REJECT_ICMPX_UNREACH:
407 if (nla_put_u8(skb, NFTA_REJECT_ICMP_CODE, priv->icmp_code))
408 goto nla_put_failure;
420 static struct nft_expr_type nft_reject_bridge_type;
421 static const struct nft_expr_ops nft_reject_bridge_ops = {
422 .type = &nft_reject_bridge_type,
423 .size = NFT_EXPR_SIZE(sizeof(struct nft_reject)),
424 .eval = nft_reject_bridge_eval,
425 .init = nft_reject_bridge_init,
426 .dump = nft_reject_bridge_dump,
427 .validate = nft_reject_bridge_validate,
430 static struct nft_expr_type nft_reject_bridge_type __read_mostly = {
431 .family = NFPROTO_BRIDGE,
433 .ops = &nft_reject_bridge_ops,
434 .policy = nft_reject_policy,
435 .maxattr = NFTA_REJECT_MAX,
436 .owner = THIS_MODULE,
439 static int __init nft_reject_bridge_module_init(void)
441 return nft_register_expr(&nft_reject_bridge_type);
444 static void __exit nft_reject_bridge_module_exit(void)
446 nft_unregister_expr(&nft_reject_bridge_type);
449 module_init(nft_reject_bridge_module_init);
450 module_exit(nft_reject_bridge_module_exit);
452 MODULE_LICENSE("GPL");
453 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
454 MODULE_ALIAS_NFT_AF_EXPR(AF_BRIDGE, "reject");