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/vrf.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         rt = __ip_route_output_key(net, fl4);
  37         if (!IS_ERR(rt))
  38                 return &rt->dst;
  39
  40         return ERR_CAST(rt);
  41 }
  42
  43 static struct dst_entry *xfrm4_dst_lookup(struct net *net, int tos, int oif,
  44                                           const xfrm_address_t *saddr,
  45                                           const xfrm_address_t *daddr)
  46 {
  47         struct flowi4 fl4;
  48
  49         return __xfrm4_dst_lookup(net, &fl4, tos, oif, saddr, daddr);
  50 }
  51
  52 static int xfrm4_get_saddr(struct net *net, int oif,
  53                            xfrm_address_t *saddr, xfrm_address_t *daddr)
  54 {
  55         struct dst_entry *dst;
  56         struct flowi4 fl4;
  57
  58         dst = __xfrm4_dst_lookup(net, &fl4, 0, oif, NULL, daddr);
  59         if (IS_ERR(dst))
  60                 return -EHOSTUNREACH;
  61
  62         saddr->a4 = fl4.saddr;
  63         dst_release(dst);
  64         return 0;
  65 }
  66
  67 static int xfrm4_get_tos(const struct flowi *fl)
  68 {
  69         return IPTOS_RT_MASK & fl->u.ip4.flowi4_tos; /* Strip ECN bits */
  70 }
  71
  72 static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst,
  73                            int nfheader_len)
  74 {
  75         return 0;
  76 }
  77
  78 static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
  79                           const struct flowi *fl)
  80 {
  81         struct rtable *rt = (struct rtable *)xdst->route;
  82         const struct flowi4 *fl4 = &fl->u.ip4;
  83
  84         xdst->u.rt.rt_iif = fl4->flowi4_iif;
  85
  86         xdst->u.dst.dev = dev;
  87         dev_hold(dev);
  88
  89         /* Sheit... I remember I did this right. Apparently,
  90          * it was magically lost, so this code needs audit */
  91         xdst->u.rt.rt_is_input = rt->rt_is_input;
  92         xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
  93                                               RTCF_LOCAL);
  94         xdst->u.rt.rt_type = rt->rt_type;
  95         xdst->u.rt.rt_gateway = rt->rt_gateway;
  96         xdst->u.rt.rt_uses_gateway = rt->rt_uses_gateway;
  97         xdst->u.rt.rt_pmtu = rt->rt_pmtu;
  98         INIT_LIST_HEAD(&xdst->u.rt.rt_uncached);
  99
 100         return 0;
 101 }
 102
 103 static void
 104 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
 105 {
 106         const struct iphdr *iph = ip_hdr(skb);
 107         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
 108         struct flowi4 *fl4 = &fl->u.ip4;
 109         int oif = 0;
 110
 111         if (skb_dst(skb)) {
 112                 oif = vrf_master_ifindex(skb_dst(skb)->dev) ?
 113                         : skb_dst(skb)->dev->ifindex;
 114         }
 115
 116         memset(fl4, 0, sizeof(struct flowi4));
 117         fl4->flowi4_mark = skb->mark;
 118         fl4->flowi4_oif = reverse ? skb->skb_iif : oif;
 119
 120         if (!ip_is_fragment(iph)) {
 121                 switch (iph->protocol) {
 122                 case IPPROTO_UDP:
 123                 case IPPROTO_UDPLITE:
 124                 case IPPROTO_TCP:
 125                 case IPPROTO_SCTP:
 126                 case IPPROTO_DCCP:
 127                         if (xprth + 4 < skb->data ||
 128                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
 129                                 __be16 *ports = (__be16 *)xprth;
 130
 131                                 fl4->fl4_sport = ports[!!reverse];
 132                                 fl4->fl4_dport = ports[!reverse];
 133                         }
 134                         break;
 135
 136                 case IPPROTO_ICMP:
 137                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 138                                 u8 *icmp = xprth;
 139
 140                                 fl4->fl4_icmp_type = icmp[0];
 141                                 fl4->fl4_icmp_code = icmp[1];
 142                         }
 143                         break;
 144
 145                 case IPPROTO_ESP:
 146                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 147                                 __be32 *ehdr = (__be32 *)xprth;
 148
 149                                 fl4->fl4_ipsec_spi = ehdr[0];
 150                         }
 151                         break;
 152
 153                 case IPPROTO_AH:
 154                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 155                                 __be32 *ah_hdr = (__be32 *)xprth;
 156
 157                                 fl4->fl4_ipsec_spi = ah_hdr[1];
 158                         }
 159                         break;
 160
 161                 case IPPROTO_COMP:
 162                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 163                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
 164
 165                                 fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 166                         }
 167                         break;
 168
 169                 case IPPROTO_GRE:
 170                         if (pskb_may_pull(skb, xprth + 12 - skb->data)) {
 171                                 __be16 *greflags = (__be16 *)xprth;
 172                                 __be32 *gre_hdr = (__be32 *)xprth;
 173
 174                                 if (greflags[0] & GRE_KEY) {
 175                                         if (greflags[0] & GRE_CSUM)
 176                                                 gre_hdr++;
 177                                         fl4->fl4_gre_key = gre_hdr[1];
 178                                 }
 179                         }
 180                         break;
 181
 182                 default:
 183                         fl4->fl4_ipsec_spi = 0;
 184                         break;
 185                 }
 186         }
 187         fl4->flowi4_proto = iph->protocol;
 188         fl4->daddr = reverse ? iph->saddr : iph->daddr;
 189         fl4->saddr = reverse ? iph->daddr : iph->saddr;
 190         fl4->flowi4_tos = iph->tos;
 191 }
 192
 193 static inline int xfrm4_garbage_collect(struct dst_ops *ops)
 194 {
 195         struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
 196
 197         xfrm4_policy_afinfo.garbage_collect(net);
 198         return (dst_entries_get_slow(ops) > ops->gc_thresh * 2);
 199 }
 200
 201 static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk,
 202                               struct sk_buff *skb, u32 mtu)
 203 {
 204         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 205         struct dst_entry *path = xdst->route;
 206
 207         path->ops->update_pmtu(path, sk, skb, mtu);
 208 }
 209
 210 static void xfrm4_redirect(struct dst_entry *dst, struct sock *sk,
 211                            struct sk_buff *skb)
 212 {
 213         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 214         struct dst_entry *path = xdst->route;
 215
 216         path->ops->redirect(path, sk, skb);
 217 }
 218
 219 static void xfrm4_dst_destroy(struct dst_entry *dst)
 220 {
 221         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 222
 223         dst_destroy_metrics_generic(dst);
 224
 225         xfrm_dst_destroy(xdst);
 226 }
 227
 228 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 229                              int unregister)
 230 {
 231         if (!unregister)
 232                 return;
 233
 234         xfrm_dst_ifdown(dst, dev);
 235 }
 236
 237 static struct dst_ops xfrm4_dst_ops = {
 238         .family =               AF_INET,
 239         .gc =                   xfrm4_garbage_collect,
 240         .update_pmtu =          xfrm4_update_pmtu,
 241         .redirect =             xfrm4_redirect,
 242         .cow_metrics =          dst_cow_metrics_generic,
 243         .destroy =              xfrm4_dst_destroy,
 244         .ifdown =               xfrm4_dst_ifdown,
 245         .local_out =            __ip_local_out,
 246         .gc_thresh =            32768,
 247 };
 248
 249 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 250         .family =               AF_INET,
 251         .dst_ops =              &xfrm4_dst_ops,
 252         .dst_lookup =           xfrm4_dst_lookup,
 253         .get_saddr =            xfrm4_get_saddr,
 254         .decode_session =       _decode_session4,
 255         .get_tos =              xfrm4_get_tos,
 256         .init_path =            xfrm4_init_path,
 257         .fill_dst =             xfrm4_fill_dst,
 258         .blackhole_route =      ipv4_blackhole_route,
 259 };
 260
 261 #ifdef CONFIG_SYSCTL
 262 static struct ctl_table xfrm4_policy_table[] = {
 263         {
 264                 .procname       = "xfrm4_gc_thresh",
 265                 .data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
 266                 .maxlen         = sizeof(int),
 267                 .mode           = 0644,
 268                 .proc_handler   = proc_dointvec,
 269         },
 270         { }
 271 };
 272
 273 static int __net_init xfrm4_net_init(struct net *net)
 274 {
 275         struct ctl_table *table;
 276         struct ctl_table_header *hdr;
 277
 278         table = xfrm4_policy_table;
 279         if (!net_eq(net, &init_net)) {
 280                 table = kmemdup(table, sizeof(xfrm4_policy_table), GFP_KERNEL);
 281                 if (!table)
 282                         goto err_alloc;
 283
 284                 table[0].data = &net->xfrm.xfrm4_dst_ops.gc_thresh;
 285         }
 286
 287         hdr = register_net_sysctl(net, "net/ipv4", table);
 288         if (!hdr)
 289                 goto err_reg;
 290
 291         net->ipv4.xfrm4_hdr = hdr;
 292         return 0;
 293
 294 err_reg:
 295         if (!net_eq(net, &init_net))
 296                 kfree(table);
 297 err_alloc:
 298         return -ENOMEM;
 299 }
 300
 301 static void __net_exit xfrm4_net_exit(struct net *net)
 302 {
 303         struct ctl_table *table;
 304
 305         if (!net->ipv4.xfrm4_hdr)
 306                 return;
 307
 308         table = net->ipv4.xfrm4_hdr->ctl_table_arg;
 309         unregister_net_sysctl_table(net->ipv4.xfrm4_hdr);
 310         if (!net_eq(net, &init_net))
 311                 kfree(table);
 312 }
 313
 314 static struct pernet_operations __net_initdata xfrm4_net_ops = {
 315         .init   = xfrm4_net_init,
 316         .exit   = xfrm4_net_exit,
 317 };
 318 #endif
 319
 320 static void __init xfrm4_policy_init(void)
 321 {
 322         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 323 }
 324
 325 void __init xfrm4_init(void)
 326 {
 327         dst_entries_init(&xfrm4_dst_ops);
 328
 329         xfrm4_state_init();
 330         xfrm4_policy_init();
 331         xfrm4_protocol_init();
 332 #ifdef CONFIG_SYSCTL
 333         register_pernet_subsys(&xfrm4_net_ops);
 334 #endif
 335 }
 336