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/nf_tables_bridge.h>
18 #include <net/netfilter/ipv4/nf_reject.h>
19 #include <net/netfilter/ipv6/nf_reject.h>
22 #include <net/ip6_checksum.h>
23 #include <linux/netfilter_bridge.h>
24 #include <linux/netfilter_ipv6.h>
25 #include "../br_private.h"
27 static void nft_reject_br_push_etherhdr(struct sk_buff *oldskb,
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);
40 /* We cannot use oldskb->dev, it can be either bridge device (NF_BRIDGE INPUT)
41 * or the bridge port (NF_BRIDGE PREROUTING).
43 static void nft_reject_br_send_v4_tcp_reset(struct sk_buff *oldskb,
44 const struct net_device *dev,
49 const struct tcphdr *oth;
52 if (!nft_bridge_iphdr_validate(oldskb))
55 oth = nf_reject_ip_tcphdr_get(oldskb, &_oth, hook);
59 nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) +
60 LL_MAX_HEADER, GFP_ATOMIC);
64 skb_reserve(nskb, LL_MAX_HEADER);
65 niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP,
66 sysctl_ip_default_ttl);
67 nf_reject_ip_tcphdr_put(nskb, oldskb, oth);
68 niph->ttl = sysctl_ip_default_ttl;
69 niph->tot_len = htons(nskb->len);
72 nft_reject_br_push_etherhdr(oldskb, nskb);
74 br_deliver(br_port_get_rcu(dev), nskb);
77 static void nft_reject_br_send_v4_unreach(struct sk_buff *oldskb,
78 const struct net_device *dev,
83 struct icmphdr *icmph;
89 if (oldskb->csum_bad || !nft_bridge_iphdr_validate(oldskb))
92 /* IP header checks: fragment. */
93 if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))
96 /* RFC says return as much as we can without exceeding 576 bytes. */
97 len = min_t(unsigned int, 536, oldskb->len);
99 if (!pskb_may_pull(oldskb, len))
102 if (pskb_trim_rcsum(oldskb, ntohs(ip_hdr(oldskb)->tot_len)))
105 if (ip_hdr(oldskb)->protocol == IPPROTO_TCP ||
106 ip_hdr(oldskb)->protocol == IPPROTO_UDP)
107 proto = ip_hdr(oldskb)->protocol;
111 if (!skb_csum_unnecessary(oldskb) &&
112 nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), proto))
115 nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmphdr) +
116 LL_MAX_HEADER + len, GFP_ATOMIC);
120 skb_reserve(nskb, LL_MAX_HEADER);
121 niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_ICMP,
122 sysctl_ip_default_ttl);
124 skb_reset_transport_header(nskb);
125 icmph = (struct icmphdr *)skb_put(nskb, sizeof(struct icmphdr));
126 memset(icmph, 0, sizeof(*icmph));
127 icmph->type = ICMP_DEST_UNREACH;
130 payload = skb_put(nskb, len);
131 memcpy(payload, skb_network_header(oldskb), len);
133 csum = csum_partial((void *)icmph, len + sizeof(struct icmphdr), 0);
134 icmph->checksum = csum_fold(csum);
136 niph->tot_len = htons(nskb->len);
139 nft_reject_br_push_etherhdr(oldskb, nskb);
141 br_deliver(br_port_get_rcu(dev), nskb);
144 static void nft_reject_br_send_v6_tcp_reset(struct net *net,
145 struct sk_buff *oldskb,
146 const struct net_device *dev,
149 struct sk_buff *nskb;
150 const struct tcphdr *oth;
152 unsigned int otcplen;
153 struct ipv6hdr *nip6h;
155 if (!nft_bridge_ip6hdr_validate(oldskb))
158 oth = nf_reject_ip6_tcphdr_get(oldskb, &_oth, &otcplen, hook);
162 nskb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(struct tcphdr) +
163 LL_MAX_HEADER, GFP_ATOMIC);
167 skb_reserve(nskb, LL_MAX_HEADER);
168 nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP,
169 net->ipv6.devconf_all->hop_limit);
170 nf_reject_ip6_tcphdr_put(nskb, oldskb, oth, otcplen);
171 nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr));
173 nft_reject_br_push_etherhdr(oldskb, nskb);
175 br_deliver(br_port_get_rcu(dev), nskb);
178 static bool reject6_br_csum_ok(struct sk_buff *skb, int hook)
180 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
183 u8 proto = ip6h->nexthdr;
188 if (skb_csum_unnecessary(skb))
191 if (ip6h->payload_len &&
192 pskb_trim_rcsum(skb, ntohs(ip6h->payload_len) + sizeof(*ip6h)))
195 thoff = ipv6_skip_exthdr(skb, ((u8*)(ip6h+1) - skb->data), &proto, &fo);
196 if (thoff < 0 || thoff >= skb->len || (fo & htons(~0x7)) != 0)
199 return nf_ip6_checksum(skb, hook, thoff, proto) == 0;
202 static void nft_reject_br_send_v6_unreach(struct net *net,
203 struct sk_buff *oldskb,
204 const struct net_device *dev,
207 struct sk_buff *nskb;
208 struct ipv6hdr *nip6h;
209 struct icmp6hdr *icmp6h;
213 if (!nft_bridge_ip6hdr_validate(oldskb))
216 /* Include "As much of invoking packet as possible without the ICMPv6
217 * packet exceeding the minimum IPv6 MTU" in the ICMP payload.
219 len = min_t(unsigned int, 1220, oldskb->len);
221 if (!pskb_may_pull(oldskb, len))
224 if (!reject6_br_csum_ok(oldskb, hook))
227 nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmp6hdr) +
228 LL_MAX_HEADER + len, GFP_ATOMIC);
232 skb_reserve(nskb, LL_MAX_HEADER);
233 nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_ICMPV6,
234 net->ipv6.devconf_all->hop_limit);
236 skb_reset_transport_header(nskb);
237 icmp6h = (struct icmp6hdr *)skb_put(nskb, sizeof(struct icmp6hdr));
238 memset(icmp6h, 0, sizeof(*icmp6h));
239 icmp6h->icmp6_type = ICMPV6_DEST_UNREACH;
240 icmp6h->icmp6_code = code;
242 payload = skb_put(nskb, len);
243 memcpy(payload, skb_network_header(oldskb), len);
244 nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr));
246 icmp6h->icmp6_cksum =
247 csum_ipv6_magic(&nip6h->saddr, &nip6h->daddr,
248 nskb->len - sizeof(struct ipv6hdr),
251 nskb->len - sizeof(struct ipv6hdr),
254 nft_reject_br_push_etherhdr(oldskb, nskb);
256 br_deliver(br_port_get_rcu(dev), nskb);
259 static void nft_reject_bridge_eval(const struct nft_expr *expr,
260 struct nft_regs *regs,
261 const struct nft_pktinfo *pkt)
263 struct nft_reject *priv = nft_expr_priv(expr);
264 const unsigned char *dest = eth_hdr(pkt->skb)->h_dest;
266 if (is_broadcast_ether_addr(dest) ||
267 is_multicast_ether_addr(dest))
270 switch (eth_hdr(pkt->skb)->h_proto) {
271 case htons(ETH_P_IP):
272 switch (priv->type) {
273 case NFT_REJECT_ICMP_UNREACH:
274 nft_reject_br_send_v4_unreach(pkt->skb, pkt->in,
278 case NFT_REJECT_TCP_RST:
279 nft_reject_br_send_v4_tcp_reset(pkt->skb, pkt->in,
282 case NFT_REJECT_ICMPX_UNREACH:
283 nft_reject_br_send_v4_unreach(pkt->skb, pkt->in,
285 nft_reject_icmp_code(priv->icmp_code));
289 case htons(ETH_P_IPV6):
290 switch (priv->type) {
291 case NFT_REJECT_ICMP_UNREACH:
292 nft_reject_br_send_v6_unreach(pkt->net, pkt->skb,
296 case NFT_REJECT_TCP_RST:
297 nft_reject_br_send_v6_tcp_reset(pkt->net, pkt->skb,
300 case NFT_REJECT_ICMPX_UNREACH:
301 nft_reject_br_send_v6_unreach(pkt->net, pkt->skb,
303 nft_reject_icmpv6_code(priv->icmp_code));
308 /* No explicit way to reject this protocol, drop it. */
312 regs->verdict.code = NF_DROP;
315 static int nft_reject_bridge_validate(const struct nft_ctx *ctx,
316 const struct nft_expr *expr,
317 const struct nft_data **data)
319 return nft_chain_validate_hooks(ctx->chain, (1 << NF_BR_PRE_ROUTING) |
320 (1 << NF_BR_LOCAL_IN));
323 static int nft_reject_bridge_init(const struct nft_ctx *ctx,
324 const struct nft_expr *expr,
325 const struct nlattr * const tb[])
327 struct nft_reject *priv = nft_expr_priv(expr);
330 err = nft_reject_bridge_validate(ctx, expr, NULL);
334 if (tb[NFTA_REJECT_TYPE] == NULL)
337 priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE]));
338 switch (priv->type) {
339 case NFT_REJECT_ICMP_UNREACH:
340 case NFT_REJECT_ICMPX_UNREACH:
341 if (tb[NFTA_REJECT_ICMP_CODE] == NULL)
344 icmp_code = nla_get_u8(tb[NFTA_REJECT_ICMP_CODE]);
345 if (priv->type == NFT_REJECT_ICMPX_UNREACH &&
346 icmp_code > NFT_REJECT_ICMPX_MAX)
349 priv->icmp_code = icmp_code;
351 case NFT_REJECT_TCP_RST:
359 static int nft_reject_bridge_dump(struct sk_buff *skb,
360 const struct nft_expr *expr)
362 const struct nft_reject *priv = nft_expr_priv(expr);
364 if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type)))
365 goto nla_put_failure;
367 switch (priv->type) {
368 case NFT_REJECT_ICMP_UNREACH:
369 case NFT_REJECT_ICMPX_UNREACH:
370 if (nla_put_u8(skb, NFTA_REJECT_ICMP_CODE, priv->icmp_code))
371 goto nla_put_failure;
383 static struct nft_expr_type nft_reject_bridge_type;
384 static const struct nft_expr_ops nft_reject_bridge_ops = {
385 .type = &nft_reject_bridge_type,
386 .size = NFT_EXPR_SIZE(sizeof(struct nft_reject)),
387 .eval = nft_reject_bridge_eval,
388 .init = nft_reject_bridge_init,
389 .dump = nft_reject_bridge_dump,
390 .validate = nft_reject_bridge_validate,
393 static struct nft_expr_type nft_reject_bridge_type __read_mostly = {
394 .family = NFPROTO_BRIDGE,
396 .ops = &nft_reject_bridge_ops,
397 .policy = nft_reject_policy,
398 .maxattr = NFTA_REJECT_MAX,
399 .owner = THIS_MODULE,
402 static int __init nft_reject_bridge_module_init(void)
404 return nft_register_expr(&nft_reject_bridge_type);
407 static void __exit nft_reject_bridge_module_exit(void)
409 nft_unregister_expr(&nft_reject_bridge_type);
412 module_init(nft_reject_bridge_module_init);
413 module_exit(nft_reject_bridge_module_exit);
415 MODULE_LICENSE("GPL");
416 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
417 MODULE_ALIAS_NFT_AF_EXPR(AF_BRIDGE, "reject");