// SPDX-License-Identifier: GPL-2.0-or-later/* * IPv4 specific functions of netfilter core * * Rusty Russell (C) 2000 * Patrick McHardy (C) 2006-2012 */#include <linux/kernel.h>#include <linux/netfilter.h>#include <linux/netfilter_ipv4.h>#include <linux/ip.h>#include <linux/skbuff.h>#include <linux/gfp.h>#include <linux/export.h>#include <net/flow.h>#include <net/route.h>#include <net/xfrm.h>#include <net/ip.h>#include <net/netfilter/nf_queue.h> /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */int ip_route_me_harder(struct net *net, struct sock *sk, struct sk_buff *skb, unsigned int addr_type){	struct net_device *dev = skb_dst_dev(skb);	const struct iphdr *iph = ip_hdr(skb);	struct rtable *rt;	struct flowi4 fl4 = {};	__be32 saddr = iph->saddr;	__u8 flags;	struct flow_keys flkeys;	unsigned int hh_len; 	sk = sk_to_full_sk(sk);	flags = sk ? inet_sk_flowi_flags(sk) : 0; 	if (addr_type == RTN_UNSPEC)		addr_type = inet_addr_type_dev_table(net, dev, saddr);	if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)		flags |= FLOWI_FLAG_ANYSRC;	else		saddr = 0; 	/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause	 * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.	 */	fl4.daddr = iph->daddr;	fl4.saddr = saddr;	fl4.flowi4_dscp = ip4h_dscp(iph);	fl4.flowi4_oif = sk ? sk->sk_bound_dev_if : 0;	fl4.flowi4_l3mdev = l3mdev_master_ifindex(dev);	fl4.flowi4_mark = skb->mark;	fl4.flowi4_flags = flags;	fib4_rules_early_flow_dissect(net, skb, &fl4, &flkeys);	rt = ip_route_output_key(net, &fl4);	if (IS_ERR(rt))		return PTR_ERR(rt); 	/* Drop old route. */	skb_dst_drop(skb);	skb_dst_set(skb, &rt->dst); 	if (skb_dst(skb)->error)		return skb_dst(skb)->error; #ifdef CONFIG_XFRM	if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&	    xfrm_decode_session(net, skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {		struct dst_entry *dst = skb_dst(skb);		/* ignore return value from skb_dstref_steal, xfrm_lookup takes		 * care of dropping the refcnt if needed.		 */		skb_dstref_steal(skb);		dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), sk, 0);		if (IS_ERR(dst))			return PTR_ERR(dst);		skb_dst_set(skb, dst);	}#endif 	/* Change in oif may mean change in hh_len. */	hh_len = skb_dst_dev(skb)->hard_header_len;	if (skb_headroom(skb) < hh_len &&	    pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),				0, GFP_ATOMIC))		return -ENOMEM; 	return 0;}EXPORT_SYMBOL(ip_route_me_harder); int nf_ip_route(struct net *net, struct dst_entry **dst, struct flowi *fl,		bool strict __always_unused){	struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);	if (IS_ERR(rt))		return PTR_ERR(rt);	*dst = &rt->dst;	return 0;}EXPORT_SYMBOL_GPL(nf_ip_route);