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Linux/net/ipv4/xfrm4_policy.c

  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 #include <net/l3mdev.h>
 19 
 20 static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
 21 
 22 static struct dst_entry *__xfrm4_dst_lookup(struct net *net, struct flowi4 *fl4,
 23                                             int tos, int oif,
 24                                             const xfrm_address_t *saddr,
 25                                             const xfrm_address_t *daddr)
 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         if (saddr)
 34                 fl4->saddr = saddr->a4;
 35 
 36         fl4->flowi4_flags = FLOWI_FLAG_SKIP_NH_OIF;
 37 
 38         rt = __ip_route_output_key(net, fl4);
 39         if (!IS_ERR(rt))
 40                 return &rt->dst;
 41 
 42         return ERR_CAST(rt);
 43 }
 44 
 45 static struct dst_entry *xfrm4_dst_lookup(struct net *net, int tos, int oif,
 46                                           const xfrm_address_t *saddr,
 47                                           const xfrm_address_t *daddr)
 48 {
 49         struct flowi4 fl4;
 50 
 51         return __xfrm4_dst_lookup(net, &fl4, tos, oif, saddr, daddr);
 52 }
 53 
 54 static int xfrm4_get_saddr(struct net *net, int oif,
 55                            xfrm_address_t *saddr, xfrm_address_t *daddr)
 56 {
 57         struct dst_entry *dst;
 58         struct flowi4 fl4;
 59 
 60         dst = __xfrm4_dst_lookup(net, &fl4, 0, oif, NULL, daddr);
 61         if (IS_ERR(dst))
 62                 return -EHOSTUNREACH;
 63 
 64         saddr->a4 = fl4.saddr;
 65         dst_release(dst);
 66         return 0;
 67 }
 68 
 69 static int xfrm4_get_tos(const struct flowi *fl)
 70 {
 71         return IPTOS_RT_MASK & fl->u.ip4.flowi4_tos; /* Strip ECN bits */
 72 }
 73 
 74 static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst,
 75                            int nfheader_len)
 76 {
 77         return 0;
 78 }
 79 
 80 static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
 81                           const struct flowi *fl)
 82 {
 83         struct rtable *rt = (struct rtable *)xdst->route;
 84         const struct flowi4 *fl4 = &fl->u.ip4;
 85 
 86         xdst->u.rt.rt_iif = fl4->flowi4_iif;
 87 
 88         xdst->u.dst.dev = dev;
 89         dev_hold(dev);
 90 
 91         /* Sheit... I remember I did this right. Apparently,
 92          * it was magically lost, so this code needs audit */
 93         xdst->u.rt.rt_is_input = rt->rt_is_input;
 94         xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
 95                                               RTCF_LOCAL);
 96         xdst->u.rt.rt_type = rt->rt_type;
 97         xdst->u.rt.rt_gateway = rt->rt_gateway;
 98         xdst->u.rt.rt_uses_gateway = rt->rt_uses_gateway;
 99         xdst->u.rt.rt_pmtu = rt->rt_pmtu;
100         xdst->u.rt.rt_table_id = rt->rt_table_id;
101         INIT_LIST_HEAD(&xdst->u.rt.rt_uncached);
102 
103         return 0;
104 }
105 
106 static void
107 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
108 {
109         const struct iphdr *iph = ip_hdr(skb);
110         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
111         struct flowi4 *fl4 = &fl->u.ip4;
112         int oif = 0;
113 
114         if (skb_dst(skb))
115                 oif = l3mdev_fib_oif(skb_dst(skb)->dev);
116 
117         memset(fl4, 0, sizeof(struct flowi4));
118         fl4->flowi4_mark = skb->mark;
119         fl4->flowi4_oif = reverse ? skb->skb_iif : oif;
120 
121         if (!ip_is_fragment(iph)) {
122                 switch (iph->protocol) {
123                 case IPPROTO_UDP:
124                 case IPPROTO_UDPLITE:
125                 case IPPROTO_TCP:
126                 case IPPROTO_SCTP:
127                 case IPPROTO_DCCP:
128                         if (xprth + 4 < skb->data ||
129                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
130                                 __be16 *ports;
131 
132                                 xprth = skb_network_header(skb) + iph->ihl * 4;
133                                 ports = (__be16 *)xprth;
134 
135                                 fl4->fl4_sport = ports[!!reverse];
136                                 fl4->fl4_dport = ports[!reverse];
137                         }
138                         break;
139 
140                 case IPPROTO_ICMP:
141                         if (xprth + 2 < skb->data ||
142                             pskb_may_pull(skb, xprth + 2 - skb->data)) {
143                                 u8 *icmp;
144 
145                                 xprth = skb_network_header(skb) + iph->ihl * 4;
146                                 icmp = xprth;
147 
148                                 fl4->fl4_icmp_type = icmp[0];
149                                 fl4->fl4_icmp_code = icmp[1];
150                         }
151                         break;
152 
153                 case IPPROTO_ESP:
154                         if (xprth + 4 < skb->data ||
155                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
156                                 __be32 *ehdr;
157 
158                                 xprth = skb_network_header(skb) + iph->ihl * 4;
159                                 ehdr = (__be32 *)xprth;
160 
161                                 fl4->fl4_ipsec_spi = ehdr[0];
162                         }
163                         break;
164 
165                 case IPPROTO_AH:
166                         if (xprth + 8 < skb->data ||
167                             pskb_may_pull(skb, xprth + 8 - skb->data)) {
168                                 __be32 *ah_hdr;
169 
170                                 xprth = skb_network_header(skb) + iph->ihl * 4;
171                                 ah_hdr = (__be32 *)xprth;
172 
173                                 fl4->fl4_ipsec_spi = ah_hdr[1];
174                         }
175                         break;
176 
177                 case IPPROTO_COMP:
178                         if (xprth + 4 < skb->data ||
179                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
180                                 __be16 *ipcomp_hdr;
181 
182                                 xprth = skb_network_header(skb) + iph->ihl * 4;
183                                 ipcomp_hdr = (__be16 *)xprth;
184 
185                                 fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
186                         }
187                         break;
188 
189                 case IPPROTO_GRE:
190                         if (xprth + 12 < skb->data ||
191                             pskb_may_pull(skb, xprth + 12 - skb->data)) {
192                                 __be16 *greflags;
193                                 __be32 *gre_hdr;
194 
195                                 xprth = skb_network_header(skb) + iph->ihl * 4;
196                                 greflags = (__be16 *)xprth;
197                                 gre_hdr = (__be32 *)xprth;
198 
199                                 if (greflags[0] & GRE_KEY) {
200                                         if (greflags[0] & GRE_CSUM)
201                                                 gre_hdr++;
202                                         fl4->fl4_gre_key = gre_hdr[1];
203                                 }
204                         }
205                         break;
206 
207                 default:
208                         fl4->fl4_ipsec_spi = 0;
209                         break;
210                 }
211         }
212         fl4->flowi4_proto = iph->protocol;
213         fl4->daddr = reverse ? iph->saddr : iph->daddr;
214         fl4->saddr = reverse ? iph->daddr : iph->saddr;
215         fl4->flowi4_tos = iph->tos;
216 }
217 
218 static inline int xfrm4_garbage_collect(struct dst_ops *ops)
219 {
220         struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
221 
222         xfrm4_policy_afinfo.garbage_collect(net);
223         return (dst_entries_get_slow(ops) > ops->gc_thresh * 2);
224 }
225 
226 static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk,
227                               struct sk_buff *skb, u32 mtu)
228 {
229         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
230         struct dst_entry *path = xdst->route;
231 
232         path->ops->update_pmtu(path, sk, skb, mtu);
233 }
234 
235 static void xfrm4_redirect(struct dst_entry *dst, struct sock *sk,
236                            struct sk_buff *skb)
237 {
238         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
239         struct dst_entry *path = xdst->route;
240 
241         path->ops->redirect(path, sk, skb);
242 }
243 
244 static void xfrm4_dst_destroy(struct dst_entry *dst)
245 {
246         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
247 
248         dst_destroy_metrics_generic(dst);
249 
250         xfrm_dst_destroy(xdst);
251 }
252 
253 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
254                              int unregister)
255 {
256         if (!unregister)
257                 return;
258 
259         xfrm_dst_ifdown(dst, dev);
260 }
261 
262 static struct dst_ops xfrm4_dst_ops_template = {
263         .family =               AF_INET,
264         .gc =                   xfrm4_garbage_collect,
265         .update_pmtu =          xfrm4_update_pmtu,
266         .redirect =             xfrm4_redirect,
267         .cow_metrics =          dst_cow_metrics_generic,
268         .destroy =              xfrm4_dst_destroy,
269         .ifdown =               xfrm4_dst_ifdown,
270         .local_out =            __ip_local_out,
271         .gc_thresh =            INT_MAX,
272 };
273 
274 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
275         .family =               AF_INET,
276         .dst_ops =              &xfrm4_dst_ops_template,
277         .dst_lookup =           xfrm4_dst_lookup,
278         .get_saddr =            xfrm4_get_saddr,
279         .decode_session =       _decode_session4,
280         .get_tos =              xfrm4_get_tos,
281         .init_path =            xfrm4_init_path,
282         .fill_dst =             xfrm4_fill_dst,
283         .blackhole_route =      ipv4_blackhole_route,
284 };
285 
286 #ifdef CONFIG_SYSCTL
287 static struct ctl_table xfrm4_policy_table[] = {
288         {
289                 .procname       = "xfrm4_gc_thresh",
290                 .data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
291                 .maxlen         = sizeof(int),
292                 .mode           = 0644,
293                 .proc_handler   = proc_dointvec,
294         },
295         { }
296 };
297 
298 static __net_init int xfrm4_net_sysctl_init(struct net *net)
299 {
300         struct ctl_table *table;
301         struct ctl_table_header *hdr;
302 
303         table = xfrm4_policy_table;
304         if (!net_eq(net, &init_net)) {
305                 table = kmemdup(table, sizeof(xfrm4_policy_table), GFP_KERNEL);
306                 if (!table)
307                         goto err_alloc;
308 
309                 table[0].data = &net->xfrm.xfrm4_dst_ops.gc_thresh;
310         }
311 
312         hdr = register_net_sysctl(net, "net/ipv4", table);
313         if (!hdr)
314                 goto err_reg;
315 
316         net->ipv4.xfrm4_hdr = hdr;
317         return 0;
318 
319 err_reg:
320         if (!net_eq(net, &init_net))
321                 kfree(table);
322 err_alloc:
323         return -ENOMEM;
324 }
325 
326 static __net_exit void xfrm4_net_sysctl_exit(struct net *net)
327 {
328         struct ctl_table *table;
329 
330         if (!net->ipv4.xfrm4_hdr)
331                 return;
332 
333         table = net->ipv4.xfrm4_hdr->ctl_table_arg;
334         unregister_net_sysctl_table(net->ipv4.xfrm4_hdr);
335         if (!net_eq(net, &init_net))
336                 kfree(table);
337 }
338 #else /* CONFIG_SYSCTL */
339 static inline int xfrm4_net_sysctl_init(struct net *net)
340 {
341         return 0;
342 }
343 
344 static inline void xfrm4_net_sysctl_exit(struct net *net)
345 {
346 }
347 #endif
348 
349 static int __net_init xfrm4_net_init(struct net *net)
350 {
351         int ret;
352 
353         memcpy(&net->xfrm.xfrm4_dst_ops, &xfrm4_dst_ops_template,
354                sizeof(xfrm4_dst_ops_template));
355         ret = dst_entries_init(&net->xfrm.xfrm4_dst_ops);
356         if (ret)
357                 return ret;
358 
359         ret = xfrm4_net_sysctl_init(net);
360         if (ret)
361                 dst_entries_destroy(&net->xfrm.xfrm4_dst_ops);
362 
363         return ret;
364 }
365 
366 static void __net_exit xfrm4_net_exit(struct net *net)
367 {
368         xfrm4_net_sysctl_exit(net);
369         dst_entries_destroy(&net->xfrm.xfrm4_dst_ops);
370 }
371 
372 static struct pernet_operations __net_initdata xfrm4_net_ops = {
373         .init   = xfrm4_net_init,
374         .exit   = xfrm4_net_exit,
375 };
376 
377 static void __init xfrm4_policy_init(void)
378 {
379         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
380 }
381 
382 void __init xfrm4_init(void)
383 {
384         xfrm4_state_init();
385         xfrm4_policy_init();
386         xfrm4_protocol_init();
387         register_pernet_subsys(&xfrm4_net_ops);
388 }
389 
390 

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