80 lines
2.0 KiB
C
80 lines
2.0 KiB
C
#include <linux/config.h>
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#ifdef CONFIG_NETFILTER
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/* IPv4 specific functions of netfilter core */
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#include <linux/kernel.h>
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#include <linux/netfilter.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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#endif /* CONFIG_NETFILTER */
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