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TOMOYO Linux Cross Reference
Linux/net/ipv4/xfrm4_policy.c

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  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 
106         return 0;
107 }
108 
109 static void
110 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
111 {
112         const struct iphdr *iph = ip_hdr(skb);
113         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
114         struct flowi4 *fl4 = &fl->u.ip4;
115         int oif = 0;
116 
117         if (skb_dst(skb))
118                 oif = skb_dst(skb)->dev->ifindex;
119 
120         memset(fl4, 0, sizeof(struct flowi4));
121         fl4->flowi4_mark = skb->mark;
122         fl4->flowi4_oif = reverse ? skb->skb_iif : oif;
123 
124         if (!ip_is_fragment(iph)) {
125                 switch (iph->protocol) {
126                 case IPPROTO_UDP:
127                 case IPPROTO_UDPLITE:
128                 case IPPROTO_TCP:
129                 case IPPROTO_SCTP:
130                 case IPPROTO_DCCP:
131                         if (xprth + 4 < skb->data ||
132                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
133                                 __be16 *ports;
134 
135                                 xprth = skb_network_header(skb) + iph->ihl * 4;
136                                 ports = (__be16 *)xprth;
137 
138                                 fl4->fl4_sport = ports[!!reverse];
139                                 fl4->fl4_dport = ports[!reverse];
140                         }
141                         break;
142 
143                 case IPPROTO_ICMP:
144                         if (xprth + 2 < skb->data ||
145                             pskb_may_pull(skb, xprth + 2 - skb->data)) {
146                                 u8 *icmp;
147 
148                                 xprth = skb_network_header(skb) + iph->ihl * 4;
149                                 icmp = xprth;
150 
151                                 fl4->fl4_icmp_type = icmp[0];
152                                 fl4->fl4_icmp_code = icmp[1];
153                         }
154                         break;
155 
156                 case IPPROTO_ESP:
157                         if (xprth + 4 < skb->data ||
158                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
159                                 __be32 *ehdr;
160 
161                                 xprth = skb_network_header(skb) + iph->ihl * 4;
162                                 ehdr = (__be32 *)xprth;
163 
164                                 fl4->fl4_ipsec_spi = ehdr[0];
165                         }
166                         break;
167 
168                 case IPPROTO_AH:
169                         if (xprth + 8 < skb->data ||
170                             pskb_may_pull(skb, xprth + 8 - skb->data)) {
171                                 __be32 *ah_hdr;
172 
173                                 xprth = skb_network_header(skb) + iph->ihl * 4;
174                                 ah_hdr = (__be32 *)xprth;
175 
176                                 fl4->fl4_ipsec_spi = ah_hdr[1];
177                         }
178                         break;
179 
180                 case IPPROTO_COMP:
181                         if (xprth + 4 < skb->data ||
182                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
183                                 __be16 *ipcomp_hdr;
184 
185                                 xprth = skb_network_header(skb) + iph->ihl * 4;
186                                 ipcomp_hdr = (__be16 *)xprth;
187 
188                                 fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
189                         }
190                         break;
191 
192                 case IPPROTO_GRE:
193                         if (xprth + 12 < skb->data ||
194                             pskb_may_pull(skb, xprth + 12 - skb->data)) {
195                                 __be16 *greflags;
196                                 __be32 *gre_hdr;
197 
198                                 xprth = skb_network_header(skb) + iph->ihl * 4;
199                                 greflags = (__be16 *)xprth;
200                                 gre_hdr = (__be32 *)xprth;
201 
202                                 if (greflags[0] & GRE_KEY) {
203                                         if (greflags[0] & GRE_CSUM)
204                                                 gre_hdr++;
205                                         fl4->fl4_gre_key = gre_hdr[1];
206                                 }
207                         }
208                         break;
209 
210                 default:
211                         fl4->fl4_ipsec_spi = 0;
212                         break;
213                 }
214         }
215         fl4->flowi4_proto = iph->protocol;
216         fl4->daddr = reverse ? iph->saddr : iph->daddr;
217         fl4->saddr = reverse ? iph->daddr : iph->saddr;
218         fl4->flowi4_tos = iph->tos;
219 }
220 
221 static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk,
222                               struct sk_buff *skb, u32 mtu)
223 {
224         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
225         struct dst_entry *path = xdst->route;
226 
227         path->ops->update_pmtu(path, sk, skb, mtu);
228 }
229 
230 static void xfrm4_redirect(struct dst_entry *dst, struct sock *sk,
231                            struct sk_buff *skb)
232 {
233         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
234         struct dst_entry *path = xdst->route;
235 
236         path->ops->redirect(path, sk, skb);
237 }
238 
239 static void xfrm4_dst_destroy(struct dst_entry *dst)
240 {
241         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
242 
243         dst_destroy_metrics_generic(dst);
244 
245         xfrm_dst_destroy(xdst);
246 }
247 
248 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
249                              int unregister)
250 {
251         if (!unregister)
252                 return;
253 
254         xfrm_dst_ifdown(dst, dev);
255 }
256 
257 static struct dst_ops xfrm4_dst_ops_template = {
258         .family =               AF_INET,
259         .update_pmtu =          xfrm4_update_pmtu,
260         .redirect =             xfrm4_redirect,
261         .cow_metrics =          dst_cow_metrics_generic,
262         .destroy =              xfrm4_dst_destroy,
263         .ifdown =               xfrm4_dst_ifdown,
264         .local_out =            __ip_local_out,
265         .gc_thresh =            32768,
266 };
267 
268 static const struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
269         .dst_ops =              &xfrm4_dst_ops_template,
270         .dst_lookup =           xfrm4_dst_lookup,
271         .get_saddr =            xfrm4_get_saddr,
272         .decode_session =       _decode_session4,
273         .get_tos =              xfrm4_get_tos,
274         .init_path =            xfrm4_init_path,
275         .fill_dst =             xfrm4_fill_dst,
276         .blackhole_route =      ipv4_blackhole_route,
277 };
278 
279 #ifdef CONFIG_SYSCTL
280 static struct ctl_table xfrm4_policy_table[] = {
281         {
282                 .procname       = "xfrm4_gc_thresh",
283                 .data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
284                 .maxlen         = sizeof(int),
285                 .mode           = 0644,
286                 .proc_handler   = proc_dointvec,
287         },
288         { }
289 };
290 
291 static __net_init int xfrm4_net_sysctl_init(struct net *net)
292 {
293         struct ctl_table *table;
294         struct ctl_table_header *hdr;
295 
296         table = xfrm4_policy_table;
297         if (!net_eq(net, &init_net)) {
298                 table = kmemdup(table, sizeof(xfrm4_policy_table), GFP_KERNEL);
299                 if (!table)
300                         goto err_alloc;
301 
302                 table[0].data = &net->xfrm.xfrm4_dst_ops.gc_thresh;
303         }
304 
305         hdr = register_net_sysctl(net, "net/ipv4", table);
306         if (!hdr)
307                 goto err_reg;
308 
309         net->ipv4.xfrm4_hdr = hdr;
310         return 0;
311 
312 err_reg:
313         if (!net_eq(net, &init_net))
314                 kfree(table);
315 err_alloc:
316         return -ENOMEM;
317 }
318 
319 static __net_exit void xfrm4_net_sysctl_exit(struct net *net)
320 {
321         struct ctl_table *table;
322 
323         if (!net->ipv4.xfrm4_hdr)
324                 return;
325 
326         table = net->ipv4.xfrm4_hdr->ctl_table_arg;
327         unregister_net_sysctl_table(net->ipv4.xfrm4_hdr);
328         if (!net_eq(net, &init_net))
329                 kfree(table);
330 }
331 #else /* CONFIG_SYSCTL */
332 static inline int xfrm4_net_sysctl_init(struct net *net)
333 {
334         return 0;
335 }
336 
337 static inline void xfrm4_net_sysctl_exit(struct net *net)
338 {
339 }
340 #endif
341 
342 static int __net_init xfrm4_net_init(struct net *net)
343 {
344         int ret;
345 
346         memcpy(&net->xfrm.xfrm4_dst_ops, &xfrm4_dst_ops_template,
347                sizeof(xfrm4_dst_ops_template));
348         ret = dst_entries_init(&net->xfrm.xfrm4_dst_ops);
349         if (ret)
350                 return ret;
351 
352         ret = xfrm4_net_sysctl_init(net);
353         if (ret)
354                 dst_entries_destroy(&net->xfrm.xfrm4_dst_ops);
355 
356         return ret;
357 }
358 
359 static void __net_exit xfrm4_net_exit(struct net *net)
360 {
361         xfrm4_net_sysctl_exit(net);
362         dst_entries_destroy(&net->xfrm.xfrm4_dst_ops);
363 }
364 
365 static struct pernet_operations __net_initdata xfrm4_net_ops = {
366         .init   = xfrm4_net_init,
367         .exit   = xfrm4_net_exit,
368 };
369 
370 static void __init xfrm4_policy_init(void)
371 {
372         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo, AF_INET);
373 }
374 
375 void __init xfrm4_init(void)
376 {
377         xfrm4_state_init();
378         xfrm4_policy_init();
379         xfrm4_protocol_init();
380         register_pernet_subsys(&xfrm4_net_ops);
381 }
382 
383 

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