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->tot_len = htons(nskb->len);
101 nft_reject_br_push_etherhdr(oldskb, nskb);
103 br_forward(br_port_get_rcu(dev), nskb, false, true);
106 static void nft_reject_br_send_v4_unreach(struct net *net,
107 struct sk_buff *oldskb,
108 const struct net_device *dev,
111 struct sk_buff *nskb;
113 struct icmphdr *icmph;
118 if (!nft_bridge_iphdr_validate(oldskb))
121 /* IP header checks: fragment. */
122 if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))
125 /* RFC says return as much as we can without exceeding 576 bytes. */
126 len = min_t(unsigned int, 536, oldskb->len);
128 if (!pskb_may_pull(oldskb, len))
131 if (pskb_trim_rcsum(oldskb, ntohs(ip_hdr(oldskb)->tot_len)))
134 if (ip_hdr(oldskb)->protocol == IPPROTO_TCP ||
135 ip_hdr(oldskb)->protocol == IPPROTO_UDP)
136 proto = ip_hdr(oldskb)->protocol;
140 if (!skb_csum_unnecessary(oldskb) &&
141 nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), proto))
144 nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmphdr) +
145 LL_MAX_HEADER + len, GFP_ATOMIC);
149 skb_reserve(nskb, LL_MAX_HEADER);
150 niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_ICMP,
151 net->ipv4.sysctl_ip_default_ttl);
153 skb_reset_transport_header(nskb);
154 icmph = skb_put_zero(nskb, sizeof(struct icmphdr));
155 icmph->type = ICMP_DEST_UNREACH;
158 skb_put_data(nskb, skb_network_header(oldskb), len);
160 csum = csum_partial((void *)icmph, len + sizeof(struct icmphdr), 0);
161 icmph->checksum = csum_fold(csum);
163 niph->tot_len = htons(nskb->len);
166 nft_reject_br_push_etherhdr(oldskb, nskb);
168 br_forward(br_port_get_rcu(dev), nskb, false, true);
171 static int nft_bridge_ip6hdr_validate(struct sk_buff *skb)
176 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
180 if (hdr->version != 6)
183 pkt_len = ntohs(hdr->payload_len);
184 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
190 static void nft_reject_br_send_v6_tcp_reset(struct net *net,
191 struct sk_buff *oldskb,
192 const struct net_device *dev,
195 struct sk_buff *nskb;
196 const struct tcphdr *oth;
198 unsigned int otcplen;
199 struct ipv6hdr *nip6h;
201 if (!nft_bridge_ip6hdr_validate(oldskb))
204 oth = nf_reject_ip6_tcphdr_get(oldskb, &_oth, &otcplen, hook);
208 nskb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(struct tcphdr) +
209 LL_MAX_HEADER, GFP_ATOMIC);
213 skb_reserve(nskb, LL_MAX_HEADER);
214 nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP,
215 net->ipv6.devconf_all->hop_limit);
216 nf_reject_ip6_tcphdr_put(nskb, oldskb, oth, otcplen);
217 nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr));
219 nft_reject_br_push_etherhdr(oldskb, nskb);
221 br_forward(br_port_get_rcu(dev), nskb, false, true);
224 static bool reject6_br_csum_ok(struct sk_buff *skb, int hook)
226 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
229 u8 proto = ip6h->nexthdr;
231 if (skb_csum_unnecessary(skb))
234 if (ip6h->payload_len &&
235 pskb_trim_rcsum(skb, ntohs(ip6h->payload_len) + sizeof(*ip6h)))
238 ip6h = ipv6_hdr(skb);
239 thoff = ipv6_skip_exthdr(skb, ((u8*)(ip6h+1) - skb->data), &proto, &fo);
240 if (thoff < 0 || thoff >= skb->len || (fo & htons(~0x7)) != 0)
243 return nf_ip6_checksum(skb, hook, thoff, proto) == 0;
246 static void nft_reject_br_send_v6_unreach(struct net *net,
247 struct sk_buff *oldskb,
248 const struct net_device *dev,
251 struct sk_buff *nskb;
252 struct ipv6hdr *nip6h;
253 struct icmp6hdr *icmp6h;
256 if (!nft_bridge_ip6hdr_validate(oldskb))
259 /* Include "As much of invoking packet as possible without the ICMPv6
260 * packet exceeding the minimum IPv6 MTU" in the ICMP payload.
262 len = min_t(unsigned int, 1220, oldskb->len);
264 if (!pskb_may_pull(oldskb, len))
267 if (!reject6_br_csum_ok(oldskb, hook))
270 nskb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(struct icmp6hdr) +
271 LL_MAX_HEADER + len, GFP_ATOMIC);
275 skb_reserve(nskb, LL_MAX_HEADER);
276 nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_ICMPV6,
277 net->ipv6.devconf_all->hop_limit);
279 skb_reset_transport_header(nskb);
280 icmp6h = skb_put_zero(nskb, sizeof(struct icmp6hdr));
281 icmp6h->icmp6_type = ICMPV6_DEST_UNREACH;
282 icmp6h->icmp6_code = code;
284 skb_put_data(nskb, skb_network_header(oldskb), len);
285 nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr));
287 icmp6h->icmp6_cksum =
288 csum_ipv6_magic(&nip6h->saddr, &nip6h->daddr,
289 nskb->len - sizeof(struct ipv6hdr),
292 nskb->len - sizeof(struct ipv6hdr),
295 nft_reject_br_push_etherhdr(oldskb, nskb);
297 br_forward(br_port_get_rcu(dev), nskb, false, true);
300 static void nft_reject_bridge_eval(const struct nft_expr *expr,
301 struct nft_regs *regs,
302 const struct nft_pktinfo *pkt)
304 struct nft_reject *priv = nft_expr_priv(expr);
305 const unsigned char *dest = eth_hdr(pkt->skb)->h_dest;
307 if (is_broadcast_ether_addr(dest) ||
308 is_multicast_ether_addr(dest))
311 switch (eth_hdr(pkt->skb)->h_proto) {
312 case htons(ETH_P_IP):
313 switch (priv->type) {
314 case NFT_REJECT_ICMP_UNREACH:
315 nft_reject_br_send_v4_unreach(nft_net(pkt), pkt->skb,
320 case NFT_REJECT_TCP_RST:
321 nft_reject_br_send_v4_tcp_reset(nft_net(pkt), pkt->skb,
325 case NFT_REJECT_ICMPX_UNREACH:
326 nft_reject_br_send_v4_unreach(nft_net(pkt), pkt->skb,
329 nft_reject_icmp_code(priv->icmp_code));
333 case htons(ETH_P_IPV6):
334 switch (priv->type) {
335 case NFT_REJECT_ICMP_UNREACH:
336 nft_reject_br_send_v6_unreach(nft_net(pkt), pkt->skb,
341 case NFT_REJECT_TCP_RST:
342 nft_reject_br_send_v6_tcp_reset(nft_net(pkt), pkt->skb,
346 case NFT_REJECT_ICMPX_UNREACH:
347 nft_reject_br_send_v6_unreach(nft_net(pkt), pkt->skb,
350 nft_reject_icmpv6_code(priv->icmp_code));
355 /* No explicit way to reject this protocol, drop it. */
359 regs->verdict.code = NF_DROP;
362 static int nft_reject_bridge_validate(const struct nft_ctx *ctx,
363 const struct nft_expr *expr,
364 const struct nft_data **data)
366 return nft_chain_validate_hooks(ctx->chain, (1 << NF_BR_PRE_ROUTING) |
367 (1 << NF_BR_LOCAL_IN));
370 static int nft_reject_bridge_init(const struct nft_ctx *ctx,
371 const struct nft_expr *expr,
372 const struct nlattr * const tb[])
374 struct nft_reject *priv = nft_expr_priv(expr);
377 if (tb[NFTA_REJECT_TYPE] == NULL)
380 priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE]));
381 switch (priv->type) {
382 case NFT_REJECT_ICMP_UNREACH:
383 case NFT_REJECT_ICMPX_UNREACH:
384 if (tb[NFTA_REJECT_ICMP_CODE] == NULL)
387 icmp_code = nla_get_u8(tb[NFTA_REJECT_ICMP_CODE]);
388 if (priv->type == NFT_REJECT_ICMPX_UNREACH &&
389 icmp_code > NFT_REJECT_ICMPX_MAX)
392 priv->icmp_code = icmp_code;
394 case NFT_REJECT_TCP_RST:
402 static int nft_reject_bridge_dump(struct sk_buff *skb,
403 const struct nft_expr *expr)
405 const struct nft_reject *priv = nft_expr_priv(expr);
407 if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type)))
408 goto nla_put_failure;
410 switch (priv->type) {
411 case NFT_REJECT_ICMP_UNREACH:
412 case NFT_REJECT_ICMPX_UNREACH:
413 if (nla_put_u8(skb, NFTA_REJECT_ICMP_CODE, priv->icmp_code))
414 goto nla_put_failure;
426 static struct nft_expr_type nft_reject_bridge_type;
427 static const struct nft_expr_ops nft_reject_bridge_ops = {
428 .type = &nft_reject_bridge_type,
429 .size = NFT_EXPR_SIZE(sizeof(struct nft_reject)),
430 .eval = nft_reject_bridge_eval,
431 .init = nft_reject_bridge_init,
432 .dump = nft_reject_bridge_dump,
433 .validate = nft_reject_bridge_validate,
436 static struct nft_expr_type nft_reject_bridge_type __read_mostly = {
437 .family = NFPROTO_BRIDGE,
439 .ops = &nft_reject_bridge_ops,
440 .policy = nft_reject_policy,
441 .maxattr = NFTA_REJECT_MAX,
442 .owner = THIS_MODULE,
445 static int __init nft_reject_bridge_module_init(void)
447 return nft_register_expr(&nft_reject_bridge_type);
450 static void __exit nft_reject_bridge_module_exit(void)
452 nft_unregister_expr(&nft_reject_bridge_type);
455 module_init(nft_reject_bridge_module_init);
456 module_exit(nft_reject_bridge_module_exit);
458 MODULE_LICENSE("GPL");
459 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
460 MODULE_ALIAS_NFT_AF_EXPR(AF_BRIDGE, "reject");