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TOMOYO Linux Cross Reference
Linux/net/ipv4/netfilter.c

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  1 /*
  2  * IPv4 specific functions of netfilter core
  3  *
  4  * Rusty Russell (C) 2000 -- This code is GPL.
  5  * Patrick McHardy (C) 2006-2012
  6  */
  7 #include <linux/kernel.h>
  8 #include <linux/netfilter.h>
  9 #include <linux/netfilter_ipv4.h>
 10 #include <linux/ip.h>
 11 #include <linux/skbuff.h>
 12 #include <linux/gfp.h>
 13 #include <linux/export.h>
 14 #include <net/route.h>
 15 #include <net/xfrm.h>
 16 #include <net/ip.h>
 17 #include <net/netfilter/nf_queue.h>
 18 
 19 /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
 20 int ip_route_me_harder(struct net *net, struct sk_buff *skb, unsigned int addr_type)
 21 {
 22         const struct iphdr *iph = ip_hdr(skb);
 23         struct rtable *rt;
 24         struct flowi4 fl4 = {};
 25         __be32 saddr = iph->saddr;
 26         const struct sock *sk = skb_to_full_sk(skb);
 27         __u8 flags = sk ? inet_sk_flowi_flags(sk) : 0;
 28         struct net_device *dev = skb_dst(skb)->dev;
 29         unsigned int hh_len;
 30 
 31         if (addr_type == RTN_UNSPEC)
 32                 addr_type = inet_addr_type_dev_table(net, dev, saddr);
 33         if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
 34                 flags |= FLOWI_FLAG_ANYSRC;
 35         else
 36                 saddr = 0;
 37 
 38         /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
 39          * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
 40          */
 41         fl4.daddr = iph->daddr;
 42         fl4.saddr = saddr;
 43         fl4.flowi4_tos = RT_TOS(iph->tos);
 44         fl4.flowi4_oif = sk ? sk->sk_bound_dev_if : 0;
 45         if (!fl4.flowi4_oif)
 46                 fl4.flowi4_oif = l3mdev_master_ifindex(dev);
 47         fl4.flowi4_mark = skb->mark;
 48         fl4.flowi4_flags = flags;
 49         rt = ip_route_output_key(net, &fl4);
 50         if (IS_ERR(rt))
 51                 return PTR_ERR(rt);
 52 
 53         /* Drop old route. */
 54         skb_dst_drop(skb);
 55         skb_dst_set(skb, &rt->dst);
 56 
 57         if (skb_dst(skb)->error)
 58                 return skb_dst(skb)->error;
 59 
 60 #ifdef CONFIG_XFRM
 61         if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
 62             xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
 63                 struct dst_entry *dst = skb_dst(skb);
 64                 skb_dst_set(skb, NULL);
 65                 dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), sk, 0);
 66                 if (IS_ERR(dst))
 67                         return PTR_ERR(dst);
 68                 skb_dst_set(skb, dst);
 69         }
 70 #endif
 71 
 72         /* Change in oif may mean change in hh_len. */
 73         hh_len = skb_dst(skb)->dev->hard_header_len;
 74         if (skb_headroom(skb) < hh_len &&
 75             pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
 76                                 0, GFP_ATOMIC))
 77                 return -ENOMEM;
 78 
 79         return 0;
 80 }
 81 EXPORT_SYMBOL(ip_route_me_harder);
 82 
 83 int nf_ip_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
 84                 bool strict __always_unused)
 85 {
 86         struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
 87         if (IS_ERR(rt))
 88                 return PTR_ERR(rt);
 89         *dst = &rt->dst;
 90         return 0;
 91 }
 92 EXPORT_SYMBOL_GPL(nf_ip_route);
 93 

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