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
 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