1/*
2 * xfrm4_policy.c
3 *
4 * Changes:
5 *	Kazunori MIYAZAWA @USAGI
6 * 	YOSHIFUJI Hideaki @USAGI
7 *		Split up af-specific portion
8 *
9 */
10
11#include <linux/err.h>
12#include <linux/kernel.h>
13#include <linux/inetdevice.h>
14#include <linux/if_tunnel.h>
15#include <net/dst.h>
16#include <net/xfrm.h>
17#include <net/ip.h>
18
19static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
20
21static struct dst_entry *__xfrm4_dst_lookup(struct net *net, struct flowi4 *fl4,
22					    int tos,
23					    const xfrm_address_t *saddr,
24					    const xfrm_address_t *daddr)
25{
26	struct rtable *rt;
27
28	memset(fl4, 0, sizeof(*fl4));
29	fl4->daddr = daddr->a4;
30	fl4->flowi4_tos = tos;
31	if (saddr)
32		fl4->saddr = saddr->a4;
33
34	rt = __ip_route_output_key(net, fl4);
35	if (!IS_ERR(rt))
36		return &rt->dst;
37
38	return ERR_CAST(rt);
39}
40
41static struct dst_entry *xfrm4_dst_lookup(struct net *net, int tos,
42					  const xfrm_address_t *saddr,
43					  const xfrm_address_t *daddr)
44{
45	struct flowi4 fl4;
46
47	return __xfrm4_dst_lookup(net, &fl4, tos, saddr, daddr);
48}
49
50static int xfrm4_get_saddr(struct net *net,
51			   xfrm_address_t *saddr, xfrm_address_t *daddr)
52{
53	struct dst_entry *dst;
54	struct flowi4 fl4;
55
56	dst = __xfrm4_dst_lookup(net, &fl4, 0, NULL, daddr);
57	if (IS_ERR(dst))
58		return -EHOSTUNREACH;
59
60	saddr->a4 = fl4.saddr;
61	dst_release(dst);
62	return 0;
63}
64
65static int xfrm4_get_tos(const struct flowi *fl)
66{
67	return IPTOS_RT_MASK & fl->u.ip4.flowi4_tos; /* Strip ECN bits */
68}
69
70static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst,
71			   int nfheader_len)
72{
73	return 0;
74}
75
76static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
77			  const struct flowi *fl)
78{
79	struct rtable *rt = (struct rtable *)xdst->route;
80	const struct flowi4 *fl4 = &fl->u.ip4;
81
82	xdst->u.rt.rt_iif = fl4->flowi4_iif;
83
84	xdst->u.dst.dev = dev;
85	dev_hold(dev);
86
87	/* Sheit... I remember I did this right. Apparently,
88	 * it was magically lost, so this code needs audit */
89	xdst->u.rt.rt_is_input = rt->rt_is_input;
90	xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
91					      RTCF_LOCAL);
92	xdst->u.rt.rt_type = rt->rt_type;
93	xdst->u.rt.rt_gateway = rt->rt_gateway;
94	xdst->u.rt.rt_uses_gateway = rt->rt_uses_gateway;
95	xdst->u.rt.rt_pmtu = rt->rt_pmtu;
96	INIT_LIST_HEAD(&xdst->u.rt.rt_uncached);
97
98	return 0;
99}
100
101static void
102_decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
103{
104	const struct iphdr *iph = ip_hdr(skb);
105	u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
106	struct flowi4 *fl4 = &fl->u.ip4;
107
108	memset(fl4, 0, sizeof(struct flowi4));
109	fl4->flowi4_mark = skb->mark;
110
111	if (!ip_is_fragment(iph)) {
112		switch (iph->protocol) {
113		case IPPROTO_UDP:
114		case IPPROTO_UDPLITE:
115		case IPPROTO_TCP:
116		case IPPROTO_SCTP:
117		case IPPROTO_DCCP:
118			if (xprth + 4 < skb->data ||
119			    pskb_may_pull(skb, xprth + 4 - skb->data)) {
120				__be16 *ports = (__be16 *)xprth;
121
122				fl4->fl4_sport = ports[!!reverse];
123				fl4->fl4_dport = ports[!reverse];
124			}
125			break;
126
127		case IPPROTO_ICMP:
128			if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
129				u8 *icmp = xprth;
130
131				fl4->fl4_icmp_type = icmp[0];
132				fl4->fl4_icmp_code = icmp[1];
133			}
134			break;
135
136		case IPPROTO_ESP:
137			if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
138				__be32 *ehdr = (__be32 *)xprth;
139
140				fl4->fl4_ipsec_spi = ehdr[0];
141			}
142			break;
143
144		case IPPROTO_AH:
145			if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
146				__be32 *ah_hdr = (__be32 *)xprth;
147
148				fl4->fl4_ipsec_spi = ah_hdr[1];
149			}
150			break;
151
152		case IPPROTO_COMP:
153			if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
154				__be16 *ipcomp_hdr = (__be16 *)xprth;
155
156				fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
157			}
158			break;
159
160		case IPPROTO_GRE:
161			if (pskb_may_pull(skb, xprth + 12 - skb->data)) {
162				__be16 *greflags = (__be16 *)xprth;
163				__be32 *gre_hdr = (__be32 *)xprth;
164
165				if (greflags[0] & GRE_KEY) {
166					if (greflags[0] & GRE_CSUM)
167						gre_hdr++;
168					fl4->fl4_gre_key = gre_hdr[1];
169				}
170			}
171			break;
172
173		default:
174			fl4->fl4_ipsec_spi = 0;
175			break;
176		}
177	}
178	fl4->flowi4_proto = iph->protocol;
179	fl4->daddr = reverse ? iph->saddr : iph->daddr;
180	fl4->saddr = reverse ? iph->daddr : iph->saddr;
181	fl4->flowi4_tos = iph->tos;
182}
183
184static inline int xfrm4_garbage_collect(struct dst_ops *ops)
185{
186	struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
187
188	xfrm4_policy_afinfo.garbage_collect(net);
189	return (dst_entries_get_slow(ops) > ops->gc_thresh * 2);
190}
191
192static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk,
193			      struct sk_buff *skb, u32 mtu)
194{
195	struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
196	struct dst_entry *path = xdst->route;
197
198	path->ops->update_pmtu(path, sk, skb, mtu);
199}
200
201static void xfrm4_redirect(struct dst_entry *dst, struct sock *sk,
202			   struct sk_buff *skb)
203{
204	struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
205	struct dst_entry *path = xdst->route;
206
207	path->ops->redirect(path, sk, skb);
208}
209
210static void xfrm4_dst_destroy(struct dst_entry *dst)
211{
212	struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
213
214	dst_destroy_metrics_generic(dst);
215
216	xfrm_dst_destroy(xdst);
217}
218
219static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
220			     int unregister)
221{
222	if (!unregister)
223		return;
224
225	xfrm_dst_ifdown(dst, dev);
226}
227
228static struct dst_ops xfrm4_dst_ops = {
229	.family =		AF_INET,
230	.protocol =		cpu_to_be16(ETH_P_IP),
231	.gc =			xfrm4_garbage_collect,
232	.update_pmtu =		xfrm4_update_pmtu,
233	.redirect =		xfrm4_redirect,
234	.cow_metrics =		dst_cow_metrics_generic,
235	.destroy =		xfrm4_dst_destroy,
236	.ifdown =		xfrm4_dst_ifdown,
237	.local_out =		__ip_local_out,
238	.gc_thresh =		1024,
239};
240
241static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
242	.family = 		AF_INET,
243	.dst_ops =		&xfrm4_dst_ops,
244	.dst_lookup =		xfrm4_dst_lookup,
245	.get_saddr =		xfrm4_get_saddr,
246	.decode_session =	_decode_session4,
247	.get_tos =		xfrm4_get_tos,
248	.init_path =		xfrm4_init_path,
249	.fill_dst =		xfrm4_fill_dst,
250	.blackhole_route =	ipv4_blackhole_route,
251};
252
253#ifdef CONFIG_SYSCTL
254static struct ctl_table xfrm4_policy_table[] = {
255	{
256		.procname       = "xfrm4_gc_thresh",
257		.data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
258		.maxlen         = sizeof(int),
259		.mode           = 0644,
260		.proc_handler   = proc_dointvec,
261	},
262	{ }
263};
264
265static int __net_init xfrm4_net_init(struct net *net)
266{
267	struct ctl_table *table;
268	struct ctl_table_header *hdr;
269
270	table = xfrm4_policy_table;
271	if (!net_eq(net, &init_net)) {
272		table = kmemdup(table, sizeof(xfrm4_policy_table), GFP_KERNEL);
273		if (!table)
274			goto err_alloc;
275
276		table[0].data = &net->xfrm.xfrm4_dst_ops.gc_thresh;
277	}
278
279	hdr = register_net_sysctl(net, "net/ipv4", table);
280	if (!hdr)
281		goto err_reg;
282
283	net->ipv4.xfrm4_hdr = hdr;
284	return 0;
285
286err_reg:
287	if (!net_eq(net, &init_net))
288		kfree(table);
289err_alloc:
290	return -ENOMEM;
291}
292
293static void __net_exit xfrm4_net_exit(struct net *net)
294{
295	struct ctl_table *table;
296
297	if (net->ipv4.xfrm4_hdr == NULL)
298		return;
299
300	table = net->ipv4.xfrm4_hdr->ctl_table_arg;
301	unregister_net_sysctl_table(net->ipv4.xfrm4_hdr);
302	if (!net_eq(net, &init_net))
303		kfree(table);
304}
305
306static struct pernet_operations __net_initdata xfrm4_net_ops = {
307	.init	= xfrm4_net_init,
308	.exit	= xfrm4_net_exit,
309};
310#endif
311
312static void __init xfrm4_policy_init(void)
313{
314	xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
315}
316
317void __init xfrm4_init(void)
318{
319	dst_entries_init(&xfrm4_dst_ops);
320
321	xfrm4_state_init();
322	xfrm4_policy_init();
323#ifdef CONFIG_SYSCTL
324	register_pernet_subsys(&xfrm4_net_ops);
325#endif
326}
327
328