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 = 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