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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 
 19 static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
 20 
 21 static 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 
 41 static 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 
 50 static 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 
 65 static int xfrm4_get_tos(const struct flowi *fl)
 66 {
 67         return IPTOS_RT_MASK & fl->u.ip4.flowi4_tos; /* Strip ECN bits */
 68 }
 69 
 70 static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst,
 71                            int nfheader_len)
 72 {
 73         return 0;
 74 }
 75 
 76 static 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 
101 static 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         int oif = 0;
108 
109         if (skb_dst(skb))
110                 oif = skb_dst(skb)->dev->ifindex;
111 
112         memset(fl4, 0, sizeof(struct flowi4));
113         fl4->flowi4_mark = skb->mark;
114         fl4->flowi4_oif = reverse ? skb->skb_iif : oif;
115 
116         if (!ip_is_fragment(iph)) {
117                 switch (iph->protocol) {
118                 case IPPROTO_UDP:
119                 case IPPROTO_UDPLITE:
120                 case IPPROTO_TCP:
121                 case IPPROTO_SCTP:
122                 case IPPROTO_DCCP:
123                         if (xprth + 4 < skb->data ||
124                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
125                                 __be16 *ports = (__be16 *)xprth;
126 
127                                 fl4->fl4_sport = ports[!!reverse];
128                                 fl4->fl4_dport = ports[!reverse];
129                         }
130                         break;
131 
132                 case IPPROTO_ICMP:
133                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
134                                 u8 *icmp = xprth;
135 
136                                 fl4->fl4_icmp_type = icmp[0];
137                                 fl4->fl4_icmp_code = icmp[1];
138                         }
139                         break;
140 
141                 case IPPROTO_ESP:
142                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
143                                 __be32 *ehdr = (__be32 *)xprth;
144 
145                                 fl4->fl4_ipsec_spi = ehdr[0];
146                         }
147                         break;
148 
149                 case IPPROTO_AH:
150                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
151                                 __be32 *ah_hdr = (__be32 *)xprth;
152 
153                                 fl4->fl4_ipsec_spi = ah_hdr[1];
154                         }
155                         break;
156 
157                 case IPPROTO_COMP:
158                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
159                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
160 
161                                 fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
162                         }
163                         break;
164 
165                 case IPPROTO_GRE:
166                         if (pskb_may_pull(skb, xprth + 12 - skb->data)) {
167                                 __be16 *greflags = (__be16 *)xprth;
168                                 __be32 *gre_hdr = (__be32 *)xprth;
169 
170                                 if (greflags[0] & GRE_KEY) {
171                                         if (greflags[0] & GRE_CSUM)
172                                                 gre_hdr++;
173                                         fl4->fl4_gre_key = gre_hdr[1];
174                                 }
175                         }
176                         break;
177 
178                 default:
179                         fl4->fl4_ipsec_spi = 0;
180                         break;
181                 }
182         }
183         fl4->flowi4_proto = iph->protocol;
184         fl4->daddr = reverse ? iph->saddr : iph->daddr;
185         fl4->saddr = reverse ? iph->daddr : iph->saddr;
186         fl4->flowi4_tos = iph->tos;
187 }
188 
189 static inline int xfrm4_garbage_collect(struct dst_ops *ops)
190 {
191         struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
192 
193         xfrm4_policy_afinfo.garbage_collect(net);
194         return (dst_entries_get_slow(ops) > ops->gc_thresh * 2);
195 }
196 
197 static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk,
198                               struct sk_buff *skb, u32 mtu)
199 {
200         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
201         struct dst_entry *path = xdst->route;
202 
203         path->ops->update_pmtu(path, sk, skb, mtu);
204 }
205 
206 static void xfrm4_redirect(struct dst_entry *dst, struct sock *sk,
207                            struct sk_buff *skb)
208 {
209         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
210         struct dst_entry *path = xdst->route;
211 
212         path->ops->redirect(path, sk, skb);
213 }
214 
215 static void xfrm4_dst_destroy(struct dst_entry *dst)
216 {
217         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
218 
219         dst_destroy_metrics_generic(dst);
220 
221         xfrm_dst_destroy(xdst);
222 }
223 
224 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
225                              int unregister)
226 {
227         if (!unregister)
228                 return;
229 
230         xfrm_dst_ifdown(dst, dev);
231 }
232 
233 static struct dst_ops xfrm4_dst_ops = {
234         .family =               AF_INET,
235         .protocol =             cpu_to_be16(ETH_P_IP),
236         .gc =                   xfrm4_garbage_collect,
237         .update_pmtu =          xfrm4_update_pmtu,
238         .redirect =             xfrm4_redirect,
239         .cow_metrics =          dst_cow_metrics_generic,
240         .destroy =              xfrm4_dst_destroy,
241         .ifdown =               xfrm4_dst_ifdown,
242         .local_out =            __ip_local_out,
243         .gc_thresh =            32768,
244 };
245 
246 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
247         .family =               AF_INET,
248         .dst_ops =              &xfrm4_dst_ops,
249         .dst_lookup =           xfrm4_dst_lookup,
250         .get_saddr =            xfrm4_get_saddr,
251         .decode_session =       _decode_session4,
252         .get_tos =              xfrm4_get_tos,
253         .init_path =            xfrm4_init_path,
254         .fill_dst =             xfrm4_fill_dst,
255         .blackhole_route =      ipv4_blackhole_route,
256 };
257 
258 #ifdef CONFIG_SYSCTL
259 static struct ctl_table xfrm4_policy_table[] = {
260         {
261                 .procname       = "xfrm4_gc_thresh",
262                 .data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
263                 .maxlen         = sizeof(int),
264                 .mode           = 0644,
265                 .proc_handler   = proc_dointvec,
266         },
267         { }
268 };
269 
270 static int __net_init xfrm4_net_init(struct net *net)
271 {
272         struct ctl_table *table;
273         struct ctl_table_header *hdr;
274 
275         table = xfrm4_policy_table;
276         if (!net_eq(net, &init_net)) {
277                 table = kmemdup(table, sizeof(xfrm4_policy_table), GFP_KERNEL);
278                 if (!table)
279                         goto err_alloc;
280 
281                 table[0].data = &net->xfrm.xfrm4_dst_ops.gc_thresh;
282         }
283 
284         hdr = register_net_sysctl(net, "net/ipv4", table);
285         if (!hdr)
286                 goto err_reg;
287 
288         net->ipv4.xfrm4_hdr = hdr;
289         return 0;
290 
291 err_reg:
292         if (!net_eq(net, &init_net))
293                 kfree(table);
294 err_alloc:
295         return -ENOMEM;
296 }
297 
298 static void __net_exit xfrm4_net_exit(struct net *net)
299 {
300         struct ctl_table *table;
301 
302         if (net->ipv4.xfrm4_hdr == NULL)
303                 return;
304 
305         table = net->ipv4.xfrm4_hdr->ctl_table_arg;
306         unregister_net_sysctl_table(net->ipv4.xfrm4_hdr);
307         if (!net_eq(net, &init_net))
308                 kfree(table);
309 }
310 
311 static struct pernet_operations __net_initdata xfrm4_net_ops = {
312         .init   = xfrm4_net_init,
313         .exit   = xfrm4_net_exit,
314 };
315 #endif
316 
317 static void __init xfrm4_policy_init(void)
318 {
319         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
320 }
321 
322 void __init xfrm4_init(void)
323 {
324         dst_entries_init(&xfrm4_dst_ops);
325 
326         xfrm4_state_init();
327         xfrm4_policy_init();
328         xfrm4_protocol_init();
329 #ifdef CONFIG_SYSCTL
330         register_pernet_subsys(&xfrm4_net_ops);
331 #endif
332 }
333 
334 

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