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 = (__be16 *)xprth;
 131
 132                                 fl4->fl4_sport = ports[!!reverse];
 133                                 fl4->fl4_dport = ports[!reverse];
 134                         }
 135                         break;
 136
 137                 case IPPROTO_ICMP:
 138                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 139                                 u8 *icmp = xprth;
 140
 141                                 fl4->fl4_icmp_type = icmp[0];
 142                                 fl4->fl4_icmp_code = icmp[1];
 143                         }
 144                         break;
 145
 146                 case IPPROTO_ESP:
 147                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 148                                 __be32 *ehdr = (__be32 *)xprth;
 149
 150                                 fl4->fl4_ipsec_spi = ehdr[0];
 151                         }
 152                         break;
 153
 154                 case IPPROTO_AH:
 155                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 156                                 __be32 *ah_hdr = (__be32 *)xprth;
 157
 158                                 fl4->fl4_ipsec_spi = ah_hdr[1];
 159                         }
 160                         break;
 161
 162                 case IPPROTO_COMP:
 163                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 164                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
 165
 166                                 fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 167                         }
 168                         break;
 169
 170                 case IPPROTO_GRE:
 171                         if (pskb_may_pull(skb, xprth + 12 - skb->data)) {
 172                                 __be16 *greflags = (__be16 *)xprth;
 173                                 __be32 *gre_hdr = (__be32 *)xprth;
 174
 175                                 if (greflags[0] & GRE_KEY) {
 176                                         if (greflags[0] & GRE_CSUM)
 177                                                 gre_hdr++;
 178                                         fl4->fl4_gre_key = gre_hdr[1];
 179                                 }
 180                         }
 181                         break;
 182
 183                 default:
 184                         fl4->fl4_ipsec_spi = 0;
 185                         break;
 186                 }
 187         }
 188         fl4->flowi4_proto = iph->protocol;
 189         fl4->daddr = reverse ? iph->saddr : iph->daddr;
 190         fl4->saddr = reverse ? iph->daddr : iph->saddr;
 191         fl4->flowi4_tos = iph->tos;
 192 }
 193
 194 static inline int xfrm4_garbage_collect(struct dst_ops *ops)
 195 {
 196         struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
 197
 198         xfrm4_policy_afinfo.garbage_collect(net);
 199         return (dst_entries_get_slow(ops) > ops->gc_thresh * 2);
 200 }
 201
 202 static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk,
 203                               struct sk_buff *skb, u32 mtu)
 204 {
 205         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 206         struct dst_entry *path = xdst->route;
 207
 208         path->ops->update_pmtu(path, sk, skb, mtu);
 209 }
 210
 211 static void xfrm4_redirect(struct dst_entry *dst, struct sock *sk,
 212                            struct sk_buff *skb)
 213 {
 214         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 215         struct dst_entry *path = xdst->route;
 216
 217         path->ops->redirect(path, sk, skb);
 218 }
 219
 220 static void xfrm4_dst_destroy(struct dst_entry *dst)
 221 {
 222         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 223
 224         dst_destroy_metrics_generic(dst);
 225
 226         xfrm_dst_destroy(xdst);
 227 }
 228
 229 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 230                              int unregister)
 231 {
 232         if (!unregister)
 233                 return;
 234
 235         xfrm_dst_ifdown(dst, dev);
 236 }
 237
 238 static struct dst_ops xfrm4_dst_ops = {
 239         .family =               AF_INET,
 240         .gc =                   xfrm4_garbage_collect,
 241         .update_pmtu =          xfrm4_update_pmtu,
 242         .redirect =             xfrm4_redirect,
 243         .cow_metrics =          dst_cow_metrics_generic,
 244         .destroy =              xfrm4_dst_destroy,
 245         .ifdown =               xfrm4_dst_ifdown,
 246         .local_out =            __ip_local_out_sk,
 247         .gc_thresh =            32768,
 248 };
 249
 250 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 251         .family =               AF_INET,
 252         .dst_ops =              &xfrm4_dst_ops,
 253         .dst_lookup =           xfrm4_dst_lookup,
 254         .get_saddr =            xfrm4_get_saddr,
 255         .decode_session =       _decode_session4,
 256         .get_tos =              xfrm4_get_tos,
 257         .init_path =            xfrm4_init_path,
 258         .fill_dst =             xfrm4_fill_dst,
 259         .blackhole_route =      ipv4_blackhole_route,
 260 };
 261
 262 #ifdef CONFIG_SYSCTL
 263 static struct ctl_table xfrm4_policy_table[] = {
 264         {
 265                 .procname       = "xfrm4_gc_thresh",
 266                 .data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
 267                 .maxlen         = sizeof(int),
 268                 .mode           = 0644,
 269                 .proc_handler   = proc_dointvec,
 270         },
 271         { }
 272 };
 273
 274 static int __net_init xfrm4_net_init(struct net *net)
 275 {
 276         struct ctl_table *table;
 277         struct ctl_table_header *hdr;
 278
 279         table = xfrm4_policy_table;
 280         if (!net_eq(net, &init_net)) {
 281                 table = kmemdup(table, sizeof(xfrm4_policy_table), GFP_KERNEL);
 282                 if (!table)
 283                         goto err_alloc;
 284
 285                 table[0].data = &net->xfrm.xfrm4_dst_ops.gc_thresh;
 286         }
 287
 288         hdr = register_net_sysctl(net, "net/ipv4", table);
 289         if (!hdr)
 290                 goto err_reg;
 291
 292         net->ipv4.xfrm4_hdr = hdr;
 293         return 0;
 294
 295 err_reg:
 296         if (!net_eq(net, &init_net))
 297                 kfree(table);
 298 err_alloc:
 299         return -ENOMEM;
 300 }
 301
 302 static void __net_exit xfrm4_net_exit(struct net *net)
 303 {
 304         struct ctl_table *table;
 305
 306         if (!net->ipv4.xfrm4_hdr)
 307                 return;
 308
 309         table = net->ipv4.xfrm4_hdr->ctl_table_arg;
 310         unregister_net_sysctl_table(net->ipv4.xfrm4_hdr);
 311         if (!net_eq(net, &init_net))
 312                 kfree(table);
 313 }
 314
 315 static struct pernet_operations __net_initdata xfrm4_net_ops = {
 316         .init   = xfrm4_net_init,
 317         .exit   = xfrm4_net_exit,
 318 };
 319 #endif
 320
 321 static void __init xfrm4_policy_init(void)
 322 {
 323         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 324 }
 325
 326 void __init xfrm4_init(void)
 327 {
 328         dst_entries_init(&xfrm4_dst_ops);
 329
 330         xfrm4_state_init();
 331         xfrm4_policy_init();
 332         xfrm4_protocol_init();
 333 #ifdef CONFIG_SYSCTL
 334         register_pernet_subsys(&xfrm4_net_ops);
 335 #endif
 336 }
 337