text: // SPDX-License-Identifier: GPL-2.0
  /*
   * xfrm4_policy.c
   *
   * Changes:
   *	Kazunori MIYAZAWA @USAGI
   * 	YOSHIFUJI Hideaki @USAGI
   *		Split up af-specific portion
   *
   */
  
  #include <linux/err.h>
  #include <linux/kernel.h>
  #include <linux/inetdevice.h>
  #include <net/dst.h>
  #include <net/xfrm.h>
  #include <net/ip.h>
  #include <net/l3mdev.h>
  
  static struct dst_entry *__xfrm4_dst_lookup(struct net *net, struct flowi4 *fl4,
  					    int tos, int oif,
  					    const xfrm_address_t *saddr,
  					    const xfrm_address_t *daddr,
  					    u32 mark)
  {
  	struct rtable *rt;
  
  	memset(fl4, 0, sizeof(*fl4));
  	fl4->daddr = daddr->a4;
  	fl4->flowi4_tos = tos;
  	fl4->flowi4_oif = l3mdev_master_ifindex_by_index(net, oif);
  	fl4->flowi4_mark = mark;
  	if (saddr)
  		fl4->saddr = saddr->a4;
  
  	fl4->flowi4_flags = FLOWI_FLAG_SKIP_NH_OIF;
  
  	rt = __ip_route_output_key(net, fl4);
  	if (!IS_ERR(rt))
  		return &rt->dst;
  
  	return ERR_CAST(rt);
  }
  
  static struct dst_entry *xfrm4_dst_lookup(struct net *net, int tos, int oif,
  					  const xfrm_address_t *saddr,
  					  const xfrm_address_t *daddr,
  					  u32 mark)
  {
  	struct flowi4 fl4;
  
  	return __xfrm4_dst_lookup(net, &fl4, tos, oif, saddr, daddr, mark);
  }
  
  static int xfrm4_get_saddr(struct net *net, int oif,
  			   xfrm_address_t *saddr, xfrm_address_t *daddr,
  			   u32 mark)
  {
  	struct dst_entry *dst;
  	struct flowi4 fl4;
  
  	dst = __xfrm4_dst_lookup(net, &fl4, 0, oif, NULL, daddr, mark);
  	if (IS_ERR(dst))
  		return -EHOSTUNREACH;
  
  	saddr->a4 = fl4.saddr;
  	dst_release(dst);
  	return 0;
  }
  
  static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
  			  const struct flowi *fl)
  {
  	struct rtable *rt = (struct rtable *)xdst->route;
  	const struct flowi4 *fl4 = &fl->u.ip4;
  
  	xdst->u.rt.rt_iif = fl4->flowi4_iif;
  
  	xdst->u.dst.dev = dev;
  	dev_hold(dev);
  
  	/* Sheit... I remember I did this right. Apparently,
  	 * it was magically lost, so this code needs audit */
  	xdst->u.rt.rt_is_input = rt->rt_is_input;
  	xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
  					      RTCF_LOCAL);
  	xdst->u.rt.rt_type = rt->rt_type;
  	xdst->u.rt.rt_gw_family = rt->rt_gw_family;
  	if (rt->rt_gw_family == AF_INET)
  		xdst->u.rt.rt_gw4 = rt->rt_gw4;
  	else if (rt->rt_gw_family == AF_INET6)
  		xdst->u.rt.rt_gw6 = rt->rt_gw6;
  	xdst->u.rt.rt_pmtu = rt->rt_pmtu;
  	xdst->u.rt.rt_mtu_locked = rt->rt_mtu_locked;
  	INIT_LIST_HEAD(&xdst->u.rt.rt_uncached);
  	rt_add_uncached_list(&xdst->u.rt);
  
  	return 0;
  }
  
  static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk,
  			      struct sk_buff *skb, u32 mtu)
  {
  	struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
  	struct dst_entry *path = xdst->route;
  
  	path->ops->update_pmtu(path, sk, skb, mtu);
  }
  
  static void xfrm4_redirect(struct dst_entry *dst, struct sock *sk,
  			   struct sk_buff *skb)
  {
  	struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
  	struct dst_entry *path = xdst->route;
  
  	path->ops->redirect(path, sk, skb);
  }
  
  static void xfrm4_dst_destroy(struct dst_entry *dst)
  {
  	struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
  
  	dst_destroy_metrics_generic(dst);
  	if (xdst->u.rt.rt_uncached_list)
  		rt_del_uncached_list(&xdst->u.rt);
  	xfrm_dst_destroy(xdst);
  }
  
  static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
  			     int unregister)
  {
  	if (!unregister)
  		return;
  
  	xfrm_dst_ifdown(dst, dev);
  }
  
  static struct dst_ops xfrm4_dst_ops_template = {
  	.family =		AF_INET,
  	.update_pmtu =		xfrm4_update_pmtu,
  	.redirect =		xfrm4_redirect,
  	.cow_metrics =		dst_cow_metrics_generic,
  	.destroy =		xfrm4_dst_destroy,
  	.ifdown =		xfrm4_dst_ifdown,
  	.local_out =		__ip_local_out,
  	.gc_thresh =		32768,
  };
  
  static const struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
  	.dst_ops =		&xfrm4_dst_ops_template,
  	.dst_lookup =		xfrm4_dst_lookup,
  	.get_saddr =		xfrm4_get_saddr,
  	.fill_dst =		xfrm4_fill_dst,
  	.blackhole_route =	ipv4_blackhole_route,
  };
  
  #ifdef CONFIG_SYSCTL
  static struct ctl_table xfrm4_policy_table[] = {
  	{
  		.procname       = "xfrm4_gc_thresh",
  		.data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
  		.maxlen         = sizeof(int),
  		.mode           = 0644,
  		.proc_handler   = proc_dointvec,
  	},
  	{ }
  };
  
  static __net_init int xfrm4_net_sysctl_init(struct net *net)
  {
  	struct ctl_table *table;
  	struct ctl_table_header *hdr;
  
  	table = xfrm4_policy_table;
  	if (!net_eq(net, &init_net)) {
  		table = kmemdup(table, sizeof(xfrm4_policy_table), GFP_KERNEL);
  		if (!table)
  			goto err_alloc;
  
  		table[0].data = &net->xfrm.xfrm4_dst_ops.gc_thresh;
  	}
  
  	hdr = register_net_sysctl(net, "net/ipv4", table);
  	if (!hdr)
  		goto err_reg;
  
  	net->ipv4.xfrm4_hdr = hdr;
  	return 0;
  
  err_reg:
  	if (!net_eq(net, &init_net))
  		kfree(table);
  err_alloc:
  	return -ENOMEM;
  }
  
  static __net_exit void xfrm4_net_sysctl_exit(struct net *net)
  {
  	struct ctl_table *table;
  
  	if (!net->ipv4.xfrm4_hdr)
  		return;
  
  	table = net->ipv4.xfrm4_hdr->ctl_table_arg;
  	unregister_net_sysctl_table(net->ipv4.xfrm4_hdr);
  	if (!net_eq(net, &init_net))
  		kfree(table);
  }
  #else /* CONFIG_SYSCTL */
  static inline int xfrm4_net_sysctl_init(struct net *net)
  {
  	return 0;
  }
  
  static inline void xfrm4_net_sysctl_exit(struct net *net)
  {
  }
  #endif
  
  static int __net_init xfrm4_net_init(struct net *net)
  {
  	int ret;
  
  	memcpy(&net->xfrm.xfrm4_dst_ops, &xfrm4_dst_ops_template,
  	       sizeof(xfrm4_dst_ops_template));
  	ret = dst_entries_init(&net->xfrm.xfrm4_dst_ops);
  	if (ret)
  		return ret;
  
  	ret = xfrm4_net_sysctl_init(net);
  	if (ret)
  		dst_entries_destroy(&net->xfrm.xfrm4_dst_ops);
  
  	return ret;
  }
  
  static void __net_exit xfrm4_net_exit(struct net *net)
  {
  	xfrm4_net_sysctl_exit(net);
  	dst_entries_destroy(&net->xfrm.xfrm4_dst_ops);
  }
  
  static struct pernet_operations __net_initdata xfrm4_net_ops = {
  	.init	= xfrm4_net_init,
  	.exit	= xfrm4_net_exit,
  };
  
  static void __init xfrm4_policy_init(void)
  {
  	xfrm_policy_register_afinfo(&xfrm4_policy_afinfo, AF_INET);
  }
  
  void __init xfrm4_init(void)
  {
  	xfrm4_state_init();
  	xfrm4_policy_init();
  	xfrm4_protocol_init();
  	register_pernet_subsys(&xfrm4_net_ops);
  }
  