1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2004 Netfilter Core Team <coreteam@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/module.h>
11 #include <net/ip6_route.h>
12 #include <net/ip6_fib.h>
13 #include <net/ip6_checksum.h>
14 #include <net/netfilter/ipv6/nf_reject.h>
15 #include <linux/netfilter_ipv6.h>
16 #include <linux/netfilter_bridge.h>
17 #include <net/netfilter/ipv6/nf_reject.h>
19 const struct tcphdr *nf_reject_ip6_tcphdr_get(struct sk_buff *oldskb,
21 unsigned int *otcplen, int hook)
23 const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
28 proto = oip6h->nexthdr;
29 tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data),
32 if ((tcphoff < 0) || (tcphoff > oldskb->len)) {
33 pr_debug("Cannot get TCP header.\n");
37 *otcplen = oldskb->len - tcphoff;
39 /* IP header checks: fragment, too short. */
40 if (proto != IPPROTO_TCP || *otcplen < sizeof(struct tcphdr)) {
41 pr_debug("proto(%d) != IPPROTO_TCP or too short (len = %d)\n",
46 otcph = skb_header_pointer(oldskb, tcphoff, sizeof(struct tcphdr),
53 pr_debug("RST is set\n");
58 if (nf_ip6_checksum(oldskb, hook, tcphoff, IPPROTO_TCP)) {
59 pr_debug("TCP checksum is invalid\n");
65 EXPORT_SYMBOL_GPL(nf_reject_ip6_tcphdr_get);
67 struct ipv6hdr *nf_reject_ip6hdr_put(struct sk_buff *nskb,
68 const struct sk_buff *oldskb,
69 __u8 protocol, int hoplimit)
72 const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
73 #define DEFAULT_TOS_VALUE 0x0U
74 const __u8 tclass = DEFAULT_TOS_VALUE;
76 skb_put(nskb, sizeof(struct ipv6hdr));
77 skb_reset_network_header(nskb);
78 ip6h = ipv6_hdr(nskb);
79 ip6_flow_hdr(ip6h, tclass, 0);
80 ip6h->hop_limit = hoplimit;
81 ip6h->nexthdr = protocol;
82 ip6h->saddr = oip6h->daddr;
83 ip6h->daddr = oip6h->saddr;
85 nskb->protocol = htons(ETH_P_IPV6);
89 EXPORT_SYMBOL_GPL(nf_reject_ip6hdr_put);
91 void nf_reject_ip6_tcphdr_put(struct sk_buff *nskb,
92 const struct sk_buff *oldskb,
93 const struct tcphdr *oth, unsigned int otcplen)
98 skb_reset_transport_header(nskb);
99 tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
100 /* Truncate to length (no data) */
101 tcph->doff = sizeof(struct tcphdr)/4;
102 tcph->source = oth->dest;
103 tcph->dest = oth->source;
107 tcph->seq = oth->ack_seq;
111 tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin +
112 otcplen - (oth->doff<<2));
117 ((u_int8_t *)tcph)[13] = 0;
119 tcph->ack = needs_ack;
124 /* Adjust TCP checksum */
125 tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr,
126 &ipv6_hdr(nskb)->daddr,
127 sizeof(struct tcphdr), IPPROTO_TCP,
129 sizeof(struct tcphdr), 0));
131 EXPORT_SYMBOL_GPL(nf_reject_ip6_tcphdr_put);
133 void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook)
135 struct sk_buff *nskb;
136 struct tcphdr _otcph;
137 const struct tcphdr *otcph;
138 unsigned int otcplen, hh_len;
139 const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
140 struct ipv6hdr *ip6h;
141 struct dst_entry *dst = NULL;
144 if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) ||
145 (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
146 pr_debug("addr is not unicast.\n");
150 otcph = nf_reject_ip6_tcphdr_get(oldskb, &_otcph, &otcplen, hook);
154 memset(&fl6, 0, sizeof(fl6));
155 fl6.flowi6_proto = IPPROTO_TCP;
156 fl6.saddr = oip6h->daddr;
157 fl6.daddr = oip6h->saddr;
158 fl6.fl6_sport = otcph->dest;
159 fl6.fl6_dport = otcph->source;
160 security_skb_classify_flow(oldskb, flowi6_to_flowi(&fl6));
161 dst = ip6_route_output(net, NULL, &fl6);
162 if (dst == NULL || dst->error) {
166 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
170 hh_len = (dst->dev->hard_header_len + 15)&~15;
171 nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
172 + sizeof(struct tcphdr) + dst->trailer_len,
176 net_dbg_ratelimited("cannot alloc skb\n");
181 skb_dst_set(nskb, dst);
183 skb_reserve(nskb, hh_len + dst->header_len);
184 ip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP,
185 ip6_dst_hoplimit(dst));
186 nf_reject_ip6_tcphdr_put(nskb, oldskb, otcph, otcplen);
188 nf_ct_attach(nskb, oldskb);
190 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
191 /* If we use ip6_local_out for bridged traffic, the MAC source on
192 * the RST will be ours, instead of the destination's. This confuses
193 * some routers/firewalls, and they drop the packet. So we need to
194 * build the eth header using the original destination's MAC as the
195 * source, and send the RST packet directly.
197 if (oldskb->nf_bridge) {
198 struct ethhdr *oeth = eth_hdr(oldskb);
200 nskb->dev = nf_bridge_get_physindev(oldskb);
201 nskb->protocol = htons(ETH_P_IPV6);
202 ip6h->payload_len = htons(sizeof(struct tcphdr));
203 if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol),
204 oeth->h_source, oeth->h_dest, nskb->len) < 0)
206 dev_queue_xmit(nskb);
209 ip6_local_out(nskb->sk, nskb);
211 EXPORT_SYMBOL_GPL(nf_send_reset6);
213 static bool reject6_csum_ok(struct sk_buff *skb, int hook)
215 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
223 if (skb_csum_unnecessary(skb))
226 proto = ip6h->nexthdr;
227 thoff = ipv6_skip_exthdr(skb, ((u8*)(ip6h+1) - skb->data), &proto, &fo);
229 if (thoff < 0 || thoff >= skb->len || (fo & htons(~0x7)) != 0)
232 return nf_ip6_checksum(skb, hook, thoff, proto) == 0;
235 void nf_send_unreach6(struct net *net, struct sk_buff *skb_in,
236 unsigned char code, unsigned int hooknum)
238 if (!reject6_csum_ok(skb_in, hooknum))
241 if (hooknum == NF_INET_LOCAL_OUT && skb_in->dev == NULL)
242 skb_in->dev = net->loopback_dev;
244 icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0);
246 EXPORT_SYMBOL_GPL(nf_send_unreach6);
248 MODULE_LICENSE("GPL");