140 lines
3.2 KiB
C
140 lines
3.2 KiB
C
/* IPv4 specific functions of netfilter core */
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#include <linux/config.h>
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#ifdef CONFIG_NETFILTER
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#include <linux/kernel.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/tcp.h>
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#include <linux/udp.h>
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#include <linux/icmp.h>
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#include <net/route.h>
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#include <linux/ip.h>
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/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
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int ip_route_me_harder(struct sk_buff **pskb)
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{
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struct iphdr *iph = (*pskb)->nh.iph;
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struct rtable *rt;
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struct flowi fl = {};
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struct dst_entry *odst;
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unsigned int hh_len;
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/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
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* packets with foreign saddr to appear on the NF_IP_LOCAL_OUT hook.
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*/
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if (inet_addr_type(iph->saddr) == RTN_LOCAL) {
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fl.nl_u.ip4_u.daddr = iph->daddr;
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fl.nl_u.ip4_u.saddr = iph->saddr;
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fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
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fl.oif = (*pskb)->sk ? (*pskb)->sk->sk_bound_dev_if : 0;
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#ifdef CONFIG_IP_ROUTE_FWMARK
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fl.nl_u.ip4_u.fwmark = (*pskb)->nfmark;
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#endif
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fl.proto = iph->protocol;
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if (ip_route_output_key(&rt, &fl) != 0)
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return -1;
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/* Drop old route. */
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dst_release((*pskb)->dst);
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(*pskb)->dst = &rt->u.dst;
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} else {
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/* non-local src, find valid iif to satisfy
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* rp-filter when calling ip_route_input. */
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fl.nl_u.ip4_u.daddr = iph->saddr;
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if (ip_route_output_key(&rt, &fl) != 0)
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return -1;
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odst = (*pskb)->dst;
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if (ip_route_input(*pskb, iph->daddr, iph->saddr,
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RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
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dst_release(&rt->u.dst);
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return -1;
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}
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dst_release(&rt->u.dst);
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dst_release(odst);
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}
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if ((*pskb)->dst->error)
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return -1;
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/* Change in oif may mean change in hh_len. */
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hh_len = (*pskb)->dst->dev->hard_header_len;
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if (skb_headroom(*pskb) < hh_len) {
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struct sk_buff *nskb;
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nskb = skb_realloc_headroom(*pskb, hh_len);
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if (!nskb)
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return -1;
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if ((*pskb)->sk)
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skb_set_owner_w(nskb, (*pskb)->sk);
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kfree_skb(*pskb);
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*pskb = nskb;
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}
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return 0;
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}
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EXPORT_SYMBOL(ip_route_me_harder);
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/*
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* Extra routing may needed on local out, as the QUEUE target never
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* returns control to the table.
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*/
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struct ip_rt_info {
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u_int32_t daddr;
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u_int32_t saddr;
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u_int8_t tos;
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};
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static void queue_save(const struct sk_buff *skb, struct nf_info *info)
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{
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struct ip_rt_info *rt_info = nf_info_reroute(info);
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if (info->hook == NF_IP_LOCAL_OUT) {
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const struct iphdr *iph = skb->nh.iph;
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rt_info->tos = iph->tos;
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rt_info->daddr = iph->daddr;
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rt_info->saddr = iph->saddr;
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}
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}
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static int queue_reroute(struct sk_buff **pskb, const struct nf_info *info)
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{
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const struct ip_rt_info *rt_info = nf_info_reroute(info);
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if (info->hook == NF_IP_LOCAL_OUT) {
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struct iphdr *iph = (*pskb)->nh.iph;
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if (!(iph->tos == rt_info->tos
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&& iph->daddr == rt_info->daddr
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&& iph->saddr == rt_info->saddr))
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return ip_route_me_harder(pskb);
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}
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return 0;
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}
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static struct nf_queue_rerouter ip_reroute = {
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.rer_size = sizeof(struct ip_rt_info),
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.save = queue_save,
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.reroute = queue_reroute,
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};
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static int init(void)
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{
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return nf_register_queue_rerouter(PF_INET, &ip_reroute);
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}
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static void fini(void)
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{
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nf_unregister_queue_rerouter(PF_INET);
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}
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module_init(init);
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module_exit(fini);
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#endif /* CONFIG_NETFILTER */
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