111 lines
3.0 KiB
C
111 lines
3.0 KiB
C
/*
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* IPv4 specific functions of netfilter core
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*
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* Rusty Russell (C) 2000 -- This code is GPL.
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* Patrick McHardy (C) 2006-2012
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*/
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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/ip.h>
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#include <linux/skbuff.h>
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#include <linux/gfp.h>
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#include <linux/export.h>
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#include <net/route.h>
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#include <net/xfrm.h>
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#include <net/ip.h>
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#include <net/netfilter/nf_queue.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 net *net, struct sk_buff *skb, unsigned int addr_type)
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{
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const struct iphdr *iph = ip_hdr(skb);
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struct rtable *rt;
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struct flowi4 fl4 = {};
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__be32 saddr = iph->saddr;
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const struct sock *sk = skb_to_full_sk(skb);
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__u8 flags = sk ? inet_sk_flowi_flags(sk) : 0;
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struct net_device *dev = skb_dst(skb)->dev;
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unsigned int hh_len;
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if (addr_type == RTN_UNSPEC)
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addr_type = inet_addr_type_dev_table(net, dev, saddr);
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if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
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flags |= FLOWI_FLAG_ANYSRC;
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else
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saddr = 0;
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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_INET_LOCAL_OUT hook.
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*/
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fl4.daddr = iph->daddr;
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fl4.saddr = saddr;
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fl4.flowi4_tos = RT_TOS(iph->tos);
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fl4.flowi4_oif = sk ? sk->sk_bound_dev_if : 0;
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if (!fl4.flowi4_oif)
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fl4.flowi4_oif = l3mdev_master_ifindex(dev);
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fl4.flowi4_mark = skb->mark;
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fl4.flowi4_flags = flags;
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rt = ip_route_output_key(net, &fl4);
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if (IS_ERR(rt))
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return PTR_ERR(rt);
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/* Drop old route. */
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skb_dst_drop(skb);
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skb_dst_set(skb, &rt->dst);
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if (skb_dst(skb)->error)
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return skb_dst(skb)->error;
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#ifdef CONFIG_XFRM
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if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
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xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
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struct dst_entry *dst = skb_dst(skb);
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skb_dst_set(skb, NULL);
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dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), sk, 0);
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if (IS_ERR(dst))
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return PTR_ERR(dst);
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skb_dst_set(skb, dst);
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}
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#endif
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/* Change in oif may mean change in hh_len. */
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hh_len = skb_dst(skb)->dev->hard_header_len;
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if (skb_headroom(skb) < hh_len &&
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pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
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0, GFP_ATOMIC))
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return -ENOMEM;
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return 0;
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}
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EXPORT_SYMBOL(ip_route_me_harder);
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int nf_ip_reroute(struct sk_buff *skb, const struct nf_queue_entry *entry)
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{
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const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
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if (entry->state.hook == NF_INET_LOCAL_OUT) {
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const struct iphdr *iph = ip_hdr(skb);
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if (!(iph->tos == rt_info->tos &&
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skb->mark == rt_info->mark &&
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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(entry->state.net, skb,
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RTN_UNSPEC);
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(nf_ip_reroute);
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int nf_ip_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
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bool strict __always_unused)
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{
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struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
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if (IS_ERR(rt))
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return PTR_ERR(rt);
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*dst = &rt->dst;
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return 0;
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}
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EXPORT_SYMBOL_GPL(nf_ip_route);
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