Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec
[muen/linux.git] / net / ipv4 / xfrm4_policy.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * xfrm4_policy.c
4  *
5  * Changes:
6  *      Kazunori MIYAZAWA @USAGI
7  *      YOSHIFUJI Hideaki @USAGI
8  *              Split up af-specific portion
9  *
10  */
11
12 #include <linux/err.h>
13 #include <linux/kernel.h>
14 #include <linux/inetdevice.h>
15 #include <linux/if_tunnel.h>
16 #include <net/dst.h>
17 #include <net/xfrm.h>
18 #include <net/ip.h>
19 #include <net/l3mdev.h>
20
21 static struct dst_entry *__xfrm4_dst_lookup(struct net *net, struct flowi4 *fl4,
22                                             int tos, int oif,
23                                             const xfrm_address_t *saddr,
24                                             const xfrm_address_t *daddr,
25                                             u32 mark)
26 {
27         struct rtable *rt;
28
29         memset(fl4, 0, sizeof(*fl4));
30         fl4->daddr = daddr->a4;
31         fl4->flowi4_tos = tos;
32         fl4->flowi4_oif = l3mdev_master_ifindex_by_index(net, oif);
33         fl4->flowi4_mark = mark;
34         if (saddr)
35                 fl4->saddr = saddr->a4;
36
37         fl4->flowi4_flags = FLOWI_FLAG_SKIP_NH_OIF;
38
39         rt = __ip_route_output_key(net, fl4);
40         if (!IS_ERR(rt))
41                 return &rt->dst;
42
43         return ERR_CAST(rt);
44 }
45
46 static struct dst_entry *xfrm4_dst_lookup(struct net *net, int tos, int oif,
47                                           const xfrm_address_t *saddr,
48                                           const xfrm_address_t *daddr,
49                                           u32 mark)
50 {
51         struct flowi4 fl4;
52
53         return __xfrm4_dst_lookup(net, &fl4, tos, oif, saddr, daddr, mark);
54 }
55
56 static int xfrm4_get_saddr(struct net *net, int oif,
57                            xfrm_address_t *saddr, xfrm_address_t *daddr,
58                            u32 mark)
59 {
60         struct dst_entry *dst;
61         struct flowi4 fl4;
62
63         dst = __xfrm4_dst_lookup(net, &fl4, 0, oif, NULL, daddr, mark);
64         if (IS_ERR(dst))
65                 return -EHOSTUNREACH;
66
67         saddr->a4 = fl4.saddr;
68         dst_release(dst);
69         return 0;
70 }
71
72 static int xfrm4_get_tos(const struct flowi *fl)
73 {
74         return IPTOS_RT_MASK & fl->u.ip4.flowi4_tos; /* Strip ECN bits */
75 }
76
77 static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst,
78                            int nfheader_len)
79 {
80         return 0;
81 }
82
83 static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
84                           const struct flowi *fl)
85 {
86         struct rtable *rt = (struct rtable *)xdst->route;
87         const struct flowi4 *fl4 = &fl->u.ip4;
88
89         xdst->u.rt.rt_iif = fl4->flowi4_iif;
90
91         xdst->u.dst.dev = dev;
92         dev_hold(dev);
93
94         /* Sheit... I remember I did this right. Apparently,
95          * it was magically lost, so this code needs audit */
96         xdst->u.rt.rt_is_input = rt->rt_is_input;
97         xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
98                                               RTCF_LOCAL);
99         xdst->u.rt.rt_type = rt->rt_type;
100         xdst->u.rt.rt_gateway = rt->rt_gateway;
101         xdst->u.rt.rt_uses_gateway = rt->rt_uses_gateway;
102         xdst->u.rt.rt_pmtu = rt->rt_pmtu;
103         xdst->u.rt.rt_table_id = rt->rt_table_id;
104         INIT_LIST_HEAD(&xdst->u.rt.rt_uncached);
105         rt_add_uncached_list(&xdst->u.rt);
106
107         return 0;
108 }
109
110 static void
111 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
112 {
113         const struct iphdr *iph = ip_hdr(skb);
114         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
115         struct flowi4 *fl4 = &fl->u.ip4;
116         int oif = 0;
117
118         if (skb_dst(skb))
119                 oif = skb_dst(skb)->dev->ifindex;
120
121         memset(fl4, 0, sizeof(struct flowi4));
122         fl4->flowi4_mark = skb->mark;
123         fl4->flowi4_oif = reverse ? skb->skb_iif : oif;
124
125         if (!ip_is_fragment(iph)) {
126                 switch (iph->protocol) {
127                 case IPPROTO_UDP:
128                 case IPPROTO_UDPLITE:
129                 case IPPROTO_TCP:
130                 case IPPROTO_SCTP:
131                 case IPPROTO_DCCP:
132                         if (xprth + 4 < skb->data ||
133                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
134                                 __be16 *ports;
135
136                                 xprth = skb_network_header(skb) + iph->ihl * 4;
137                                 ports = (__be16 *)xprth;
138
139                                 fl4->fl4_sport = ports[!!reverse];
140                                 fl4->fl4_dport = ports[!reverse];
141                         }
142                         break;
143
144                 case IPPROTO_ICMP:
145                         if (xprth + 2 < skb->data ||
146                             pskb_may_pull(skb, xprth + 2 - skb->data)) {
147                                 u8 *icmp;
148
149                                 xprth = skb_network_header(skb) + iph->ihl * 4;
150                                 icmp = xprth;
151
152                                 fl4->fl4_icmp_type = icmp[0];
153                                 fl4->fl4_icmp_code = icmp[1];
154                         }
155                         break;
156
157                 case IPPROTO_ESP:
158                         if (xprth + 4 < skb->data ||
159                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
160                                 __be32 *ehdr;
161
162                                 xprth = skb_network_header(skb) + iph->ihl * 4;
163                                 ehdr = (__be32 *)xprth;
164
165                                 fl4->fl4_ipsec_spi = ehdr[0];
166                         }
167                         break;
168
169                 case IPPROTO_AH:
170                         if (xprth + 8 < skb->data ||
171                             pskb_may_pull(skb, xprth + 8 - skb->data)) {
172                                 __be32 *ah_hdr;
173
174                                 xprth = skb_network_header(skb) + iph->ihl * 4;
175                                 ah_hdr = (__be32 *)xprth;
176
177                                 fl4->fl4_ipsec_spi = ah_hdr[1];
178                         }
179                         break;
180
181                 case IPPROTO_COMP:
182                         if (xprth + 4 < skb->data ||
183                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
184                                 __be16 *ipcomp_hdr;
185
186                                 xprth = skb_network_header(skb) + iph->ihl * 4;
187                                 ipcomp_hdr = (__be16 *)xprth;
188
189                                 fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
190                         }
191                         break;
192
193                 case IPPROTO_GRE:
194                         if (xprth + 12 < skb->data ||
195                             pskb_may_pull(skb, xprth + 12 - skb->data)) {
196                                 __be16 *greflags;
197                                 __be32 *gre_hdr;
198
199                                 xprth = skb_network_header(skb) + iph->ihl * 4;
200                                 greflags = (__be16 *)xprth;
201                                 gre_hdr = (__be32 *)xprth;
202
203                                 if (greflags[0] & GRE_KEY) {
204                                         if (greflags[0] & GRE_CSUM)
205                                                 gre_hdr++;
206                                         fl4->fl4_gre_key = gre_hdr[1];
207                                 }
208                         }
209                         break;
210
211                 default:
212                         fl4->fl4_ipsec_spi = 0;
213                         break;
214                 }
215         }
216         fl4->flowi4_proto = iph->protocol;
217         fl4->daddr = reverse ? iph->saddr : iph->daddr;
218         fl4->saddr = reverse ? iph->daddr : iph->saddr;
219         fl4->flowi4_tos = iph->tos;
220 }
221
222 static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk,
223                               struct sk_buff *skb, u32 mtu)
224 {
225         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
226         struct dst_entry *path = xdst->route;
227
228         path->ops->update_pmtu(path, sk, skb, mtu);
229 }
230
231 static void xfrm4_redirect(struct dst_entry *dst, struct sock *sk,
232                            struct sk_buff *skb)
233 {
234         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
235         struct dst_entry *path = xdst->route;
236
237         path->ops->redirect(path, sk, skb);
238 }
239
240 static void xfrm4_dst_destroy(struct dst_entry *dst)
241 {
242         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
243
244         dst_destroy_metrics_generic(dst);
245         if (xdst->u.rt.rt_uncached_list)
246                 rt_del_uncached_list(&xdst->u.rt);
247         xfrm_dst_destroy(xdst);
248 }
249
250 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
251                              int unregister)
252 {
253         if (!unregister)
254                 return;
255
256         xfrm_dst_ifdown(dst, dev);
257 }
258
259 static struct dst_ops xfrm4_dst_ops_template = {
260         .family =               AF_INET,
261         .update_pmtu =          xfrm4_update_pmtu,
262         .redirect =             xfrm4_redirect,
263         .cow_metrics =          dst_cow_metrics_generic,
264         .destroy =              xfrm4_dst_destroy,
265         .ifdown =               xfrm4_dst_ifdown,
266         .local_out =            __ip_local_out,
267         .gc_thresh =            32768,
268 };
269
270 static const struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
271         .dst_ops =              &xfrm4_dst_ops_template,
272         .dst_lookup =           xfrm4_dst_lookup,
273         .get_saddr =            xfrm4_get_saddr,
274         .decode_session =       _decode_session4,
275         .get_tos =              xfrm4_get_tos,
276         .init_path =            xfrm4_init_path,
277         .fill_dst =             xfrm4_fill_dst,
278         .blackhole_route =      ipv4_blackhole_route,
279 };
280
281 #ifdef CONFIG_SYSCTL
282 static struct ctl_table xfrm4_policy_table[] = {
283         {
284                 .procname       = "xfrm4_gc_thresh",
285                 .data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
286                 .maxlen         = sizeof(int),
287                 .mode           = 0644,
288                 .proc_handler   = proc_dointvec,
289         },
290         { }
291 };
292
293 static __net_init int xfrm4_net_sysctl_init(struct net *net)
294 {
295         struct ctl_table *table;
296         struct ctl_table_header *hdr;
297
298         table = xfrm4_policy_table;
299         if (!net_eq(net, &init_net)) {
300                 table = kmemdup(table, sizeof(xfrm4_policy_table), GFP_KERNEL);
301                 if (!table)
302                         goto err_alloc;
303
304                 table[0].data = &net->xfrm.xfrm4_dst_ops.gc_thresh;
305         }
306
307         hdr = register_net_sysctl(net, "net/ipv4", table);
308         if (!hdr)
309                 goto err_reg;
310
311         net->ipv4.xfrm4_hdr = hdr;
312         return 0;
313
314 err_reg:
315         if (!net_eq(net, &init_net))
316                 kfree(table);
317 err_alloc:
318         return -ENOMEM;
319 }
320
321 static __net_exit void xfrm4_net_sysctl_exit(struct net *net)
322 {
323         struct ctl_table *table;
324
325         if (!net->ipv4.xfrm4_hdr)
326                 return;
327
328         table = net->ipv4.xfrm4_hdr->ctl_table_arg;
329         unregister_net_sysctl_table(net->ipv4.xfrm4_hdr);
330         if (!net_eq(net, &init_net))
331                 kfree(table);
332 }
333 #else /* CONFIG_SYSCTL */
334 static inline int xfrm4_net_sysctl_init(struct net *net)
335 {
336         return 0;
337 }
338
339 static inline void xfrm4_net_sysctl_exit(struct net *net)
340 {
341 }
342 #endif
343
344 static int __net_init xfrm4_net_init(struct net *net)
345 {
346         int ret;
347
348         memcpy(&net->xfrm.xfrm4_dst_ops, &xfrm4_dst_ops_template,
349                sizeof(xfrm4_dst_ops_template));
350         ret = dst_entries_init(&net->xfrm.xfrm4_dst_ops);
351         if (ret)
352                 return ret;
353
354         ret = xfrm4_net_sysctl_init(net);
355         if (ret)
356                 dst_entries_destroy(&net->xfrm.xfrm4_dst_ops);
357
358         return ret;
359 }
360
361 static void __net_exit xfrm4_net_exit(struct net *net)
362 {
363         xfrm4_net_sysctl_exit(net);
364         dst_entries_destroy(&net->xfrm.xfrm4_dst_ops);
365 }
366
367 static struct pernet_operations __net_initdata xfrm4_net_ops = {
368         .init   = xfrm4_net_init,
369         .exit   = xfrm4_net_exit,
370 };
371
372 static void __init xfrm4_policy_init(void)
373 {
374         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo, AF_INET);
375 }
376
377 void __init xfrm4_init(void)
378 {
379         xfrm4_state_init();
380         xfrm4_policy_init();
381         xfrm4_protocol_init();
382         register_pernet_subsys(&xfrm4_net_ops);
383 }
384