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);
38 if (skb_vlan_tag_present(oldskb)) {
39 u16 vid = skb_vlan_tag_get(oldskb);
41 __vlan_hwaccel_put_tag(nskb, oldskb->vlan_proto, vid);
45 static int nft_bridge_iphdr_validate(struct sk_buff *skb)
50 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
54 if (iph->ihl < 5 || iph->version != 4)
57 len = ntohs(iph->tot_len);
60 else if (len < (iph->ihl*4))
63 if (!pskb_may_pull(skb, iph->ihl*4))
69 /* We cannot use oldskb->dev, it can be either bridge device (NF_BRIDGE INPUT)
70 * or the bridge port (NF_BRIDGE PREROUTING).
72 static void nft_reject_br_send_v4_tcp_reset(struct net *net,
73 struct sk_buff *oldskb,
74 const struct net_device *dev,
79 const struct tcphdr *oth;
82 if (!nft_bridge_iphdr_validate(oldskb))
85 oth = nf_reject_ip_tcphdr_get(oldskb, &_oth, hook);
89 nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) +
90 LL_MAX_HEADER, GFP_ATOMIC);
94 skb_reserve(nskb, LL_MAX_HEADER);
95 niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP,
96 net->ipv4.sysctl_ip_default_ttl);
97 nf_reject_ip_tcphdr_put(nskb, oldskb, oth);
98 niph->ttl = net->ipv4.sysctl_ip_default_ttl;
99 niph->tot_len = htons(nskb->len);
102 nft_reject_br_push_etherhdr(oldskb, nskb);
104 br_forward(br_port_get_rcu(dev), nskb, false, true);
107 static void nft_reject_br_send_v4_unreach(struct net *net,
108 struct sk_buff *oldskb,
109 const struct net_device *dev,
112 struct sk_buff *nskb;
114 struct icmphdr *icmph;
119 if (!nft_bridge_iphdr_validate(oldskb))
122 /* IP header checks: fragment. */
123 if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))
126 /* RFC says return as much as we can without exceeding 576 bytes. */
127 len = min_t(unsigned int, 536, oldskb->len);
129 if (!pskb_may_pull(oldskb, len))
132 if (pskb_trim_rcsum(oldskb, ntohs(ip_hdr(oldskb)->tot_len)))
135 if (ip_hdr(oldskb)->protocol == IPPROTO_TCP ||
136 ip_hdr(oldskb)->protocol == IPPROTO_UDP)
137 proto = ip_hdr(oldskb)->protocol;
141 if (!skb_csum_unnecessary(oldskb) &&
142 nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), proto))
145 nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmphdr) +
146 LL_MAX_HEADER + len, GFP_ATOMIC);
150 skb_reserve(nskb, LL_MAX_HEADER);
151 niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_ICMP,
152 net->ipv4.sysctl_ip_default_ttl);
154 skb_reset_transport_header(nskb);
155 icmph = skb_put_zero(nskb, sizeof(struct icmphdr));
156 icmph->type = ICMP_DEST_UNREACH;
159 skb_put_data(nskb, skb_network_header(oldskb), len);
161 csum = csum_partial((void *)icmph, len + sizeof(struct icmphdr), 0);
162 icmph->checksum = csum_fold(csum);
164 niph->tot_len = htons(nskb->len);
167 nft_reject_br_push_etherhdr(oldskb, nskb);
169 br_forward(br_port_get_rcu(dev), nskb, false, true);
172 static int nft_bridge_ip6hdr_validate(struct sk_buff *skb)
177 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
181 if (hdr->version != 6)
184 pkt_len = ntohs(hdr->payload_len);
185 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
191 static void nft_reject_br_send_v6_tcp_reset(struct net *net,
192 struct sk_buff *oldskb,
193 const struct net_device *dev,
196 struct sk_buff *nskb;
197 const struct tcphdr *oth;
199 unsigned int otcplen;
200 struct ipv6hdr *nip6h;
202 if (!nft_bridge_ip6hdr_validate(oldskb))
205 oth = nf_reject_ip6_tcphdr_get(oldskb, &_oth, &otcplen, hook);
209 nskb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(struct tcphdr) +
210 LL_MAX_HEADER, GFP_ATOMIC);
214 skb_reserve(nskb, LL_MAX_HEADER);
215 nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP,
216 net->ipv6.devconf_all->hop_limit);
217 nf_reject_ip6_tcphdr_put(nskb, oldskb, oth, otcplen);
218 nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr));
220 nft_reject_br_push_etherhdr(oldskb, nskb);
222 br_forward(br_port_get_rcu(dev), nskb, false, true);
225 static bool reject6_br_csum_ok(struct sk_buff *skb, int hook)
227 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
230 u8 proto = ip6h->nexthdr;
232 if (skb_csum_unnecessary(skb))
235 if (ip6h->payload_len &&
236 pskb_trim_rcsum(skb, ntohs(ip6h->payload_len) + sizeof(*ip6h)))
239 ip6h = ipv6_hdr(skb);
240 thoff = ipv6_skip_exthdr(skb, ((u8*)(ip6h+1) - skb->data), &proto, &fo);
241 if (thoff < 0 || thoff >= skb->len || (fo & htons(~0x7)) != 0)
244 return nf_ip6_checksum(skb, hook, thoff, proto) == 0;
247 static void nft_reject_br_send_v6_unreach(struct net *net,
248 struct sk_buff *oldskb,
249 const struct net_device *dev,
252 struct sk_buff *nskb;
253 struct ipv6hdr *nip6h;
254 struct icmp6hdr *icmp6h;
257 if (!nft_bridge_ip6hdr_validate(oldskb))
260 /* Include "As much of invoking packet as possible without the ICMPv6
261 * packet exceeding the minimum IPv6 MTU" in the ICMP payload.
263 len = min_t(unsigned int, 1220, oldskb->len);
265 if (!pskb_may_pull(oldskb, len))
268 if (!reject6_br_csum_ok(oldskb, hook))
271 nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmp6hdr) +
272 LL_MAX_HEADER + len, GFP_ATOMIC);
276 skb_reserve(nskb, LL_MAX_HEADER);
277 nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_ICMPV6,
278 net->ipv6.devconf_all->hop_limit);
280 skb_reset_transport_header(nskb);
281 icmp6h = skb_put_zero(nskb, sizeof(struct icmp6hdr));
282 icmp6h->icmp6_type = ICMPV6_DEST_UNREACH;
283 icmp6h->icmp6_code = code;
285 skb_put_data(nskb, skb_network_header(oldskb), len);
286 nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr));
288 icmp6h->icmp6_cksum =
289 csum_ipv6_magic(&nip6h->saddr, &nip6h->daddr,
290 nskb->len - sizeof(struct ipv6hdr),
293 nskb->len - sizeof(struct ipv6hdr),
296 nft_reject_br_push_etherhdr(oldskb, nskb);
298 br_forward(br_port_get_rcu(dev), nskb, false, true);
301 static void nft_reject_bridge_eval(const struct nft_expr *expr,
302 struct nft_regs *regs,
303 const struct nft_pktinfo *pkt)
305 struct nft_reject *priv = nft_expr_priv(expr);
306 const unsigned char *dest = eth_hdr(pkt->skb)->h_dest;
308 if (is_broadcast_ether_addr(dest) ||
309 is_multicast_ether_addr(dest))
312 switch (eth_hdr(pkt->skb)->h_proto) {
313 case htons(ETH_P_IP):
314 switch (priv->type) {
315 case NFT_REJECT_ICMP_UNREACH:
316 nft_reject_br_send_v4_unreach(nft_net(pkt), pkt->skb,
321 case NFT_REJECT_TCP_RST:
322 nft_reject_br_send_v4_tcp_reset(nft_net(pkt), pkt->skb,
326 case NFT_REJECT_ICMPX_UNREACH:
327 nft_reject_br_send_v4_unreach(nft_net(pkt), pkt->skb,
330 nft_reject_icmp_code(priv->icmp_code));
334 case htons(ETH_P_IPV6):
335 switch (priv->type) {
336 case NFT_REJECT_ICMP_UNREACH:
337 nft_reject_br_send_v6_unreach(nft_net(pkt), pkt->skb,
342 case NFT_REJECT_TCP_RST:
343 nft_reject_br_send_v6_tcp_reset(nft_net(pkt), pkt->skb,
347 case NFT_REJECT_ICMPX_UNREACH:
348 nft_reject_br_send_v6_unreach(nft_net(pkt), pkt->skb,
351 nft_reject_icmpv6_code(priv->icmp_code));
356 /* No explicit way to reject this protocol, drop it. */
360 regs->verdict.code = NF_DROP;
363 static int nft_reject_bridge_validate(const struct nft_ctx *ctx,
364 const struct nft_expr *expr,
365 const struct nft_data **data)
367 return nft_chain_validate_hooks(ctx->chain, (1 << NF_BR_PRE_ROUTING) |
368 (1 << NF_BR_LOCAL_IN));
371 static int nft_reject_bridge_init(const struct nft_ctx *ctx,
372 const struct nft_expr *expr,
373 const struct nlattr * const tb[])
375 struct nft_reject *priv = nft_expr_priv(expr);
378 if (tb[NFTA_REJECT_TYPE] == NULL)
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)
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)
393 priv->icmp_code = icmp_code;
395 case NFT_REJECT_TCP_RST:
403 static int nft_reject_bridge_dump(struct sk_buff *skb,
404 const struct nft_expr *expr)
406 const struct nft_reject *priv = nft_expr_priv(expr);
408 if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type)))
409 goto nla_put_failure;
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;
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,
432 .init = nft_reject_bridge_init,
433 .dump = nft_reject_bridge_dump,
434 .validate = nft_reject_bridge_validate,
437 static struct nft_expr_type nft_reject_bridge_type __read_mostly = {
438 .family = NFPROTO_BRIDGE,
440 .ops = &nft_reject_bridge_ops,
441 .policy = nft_reject_policy,
442 .maxattr = NFTA_REJECT_MAX,
443 .owner = THIS_MODULE,
446 static int __init nft_reject_bridge_module_init(void)
448 return nft_register_expr(&nft_reject_bridge_type);
451 static void __exit nft_reject_bridge_module_exit(void)
453 nft_unregister_expr(&nft_reject_bridge_type);
456 module_init(nft_reject_bridge_module_init);
457 module_exit(nft_reject_bridge_module_exit);
459 MODULE_LICENSE("GPL");
460 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
461 MODULE_ALIAS_NFT_AF_EXPR(AF_BRIDGE, "reject");