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/config.h>
  12 #include <net/xfrm.h>
  13 #include <net/ip.h>
  14
  15 extern struct dst_ops xfrm4_dst_ops;
  16 extern struct xfrm_policy_afinfo xfrm4_policy_afinfo;
  17
  18 static struct xfrm_type_map xfrm4_type_map = { .lock = RW_LOCK_UNLOCKED };
  19
  20 static int xfrm4_dst_lookup(struct xfrm_dst **dst, struct flowi *fl)
  21 {
  22         return __ip_route_output_key((struct rtable**)dst, fl);
  23 }
  24
  25 /* Check that the bundle accepts the flow and its components are
  26  * still valid.
  27  */
  28
  29 static int __xfrm4_bundle_ok(struct xfrm_dst *xdst, struct flowi *fl)
  30 {
  31         do {
  32                 if (xdst->u.dst.ops != &xfrm4_dst_ops)
  33                         return 1;
  34
  35                 if (!xfrm_selector_match(&xdst->u.dst.xfrm->sel, fl, AF_INET))
  36                         return 0;
  37                 if (xdst->u.dst.xfrm->km.state != XFRM_STATE_VALID ||
  38                     xdst->u.dst.path->obsolete > 0)
  39                         return 0;
  40                 xdst = (struct xfrm_dst*)xdst->u.dst.child;
  41         } while (xdst);
  42         return 0;
  43 }
  44
  45 static struct dst_entry *
  46 __xfrm4_find_bundle(struct flowi *fl, struct rtable *rt, struct xfrm_policy *policy)
  47 {
  48         struct dst_entry *dst;
  49
  50         if (!fl->fl4_src)
  51                 fl->fl4_src = rt->rt_src;
  52         if (!fl->fl4_dst)
  53                 fl->fl4_dst = rt->rt_dst;
  54         read_lock_bh(&policy->lock);
  55         for (dst = policy->bundles; dst; dst = dst->next) {
  56                 struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
  57                 if (xdst->u.rt.fl.oif == fl->oif &&     /*XXX*/
  58                     xdst->u.rt.fl.fl4_dst == fl->fl4_dst &&
  59                     xdst->u.rt.fl.fl4_src == fl->fl4_src &&
  60                     __xfrm4_bundle_ok(xdst, fl)) {
  61                         dst_clone(dst);
  62                         break;
  63                 }
  64         }
  65         read_unlock_bh(&policy->lock);
  66         return dst;
  67 }
  68
  69 /* Allocate chain of dst_entry's, attach known xfrm's, calculate
  70  * all the metrics... Shortly, bundle a bundle.
  71  */
  72
  73 static int
  74 __xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int nx,
  75                       struct flowi *fl, struct dst_entry **dst_p)
  76 {
  77         struct dst_entry *dst, *dst_prev;
  78         struct rtable *rt0 = (struct rtable*)(*dst_p);
  79         struct rtable *rt = rt0;
  80         u32 remote = fl->fl4_dst;
  81         u32 local  = fl->fl4_src;
  82         int i;
  83         int err;
  84         int header_len = 0;
  85         int trailer_len = 0;
  86
  87         dst = dst_prev = NULL;
  88
  89         for (i = 0; i < nx; i++) {
  90                 struct dst_entry *dst1 = dst_alloc(&xfrm4_dst_ops);
  91
  92                 if (unlikely(dst1 == NULL)) {
  93                         err = -ENOBUFS;
  94                         goto error;
  95                 }
  96
  97                 dst1->xfrm = xfrm[i];
  98                 if (!dst)
  99                         dst = dst1;
 100                 else {
 101                         dst_prev->child = dst1;
 102                         dst1->flags |= DST_NOHASH;
 103                         dst_clone(dst1);
 104                 }
 105                 dst_prev = dst1;
 106                 if (xfrm[i]->props.mode) {
 107                         remote = xfrm[i]->id.daddr.a4;
 108                         local  = xfrm[i]->props.saddr.a4;
 109                 }
 110                 header_len += xfrm[i]->props.header_len;
 111                 trailer_len += xfrm[i]->props.trailer_len;
 112         }
 113
 114         if (remote != fl->fl4_dst) {
 115                 struct flowi fl_tunnel = { .nl_u = { .ip4_u =
 116                                                      { .daddr = remote,
 117                                                        .saddr = local }
 118                                                    }
 119                                          };
 120                 err = xfrm_dst_lookup((struct xfrm_dst**)&rt, &fl_tunnel, AF_INET);
 121                 if (err)
 122                         goto error;
 123         } else {
 124                 dst_hold(&rt->u.dst);
 125         }
 126         dst_prev->child = &rt->u.dst;
 127         for (dst_prev = dst; dst_prev != &rt->u.dst; dst_prev = dst_prev->child) {
 128                 struct xfrm_dst *x = (struct xfrm_dst*)dst_prev;
 129                 x->u.rt.fl = *fl;
 130
 131                 dst_prev->dev = rt->u.dst.dev;
 132                 if (rt->u.dst.dev)
 133                         dev_hold(rt->u.dst.dev);
 134                 dst_prev->obsolete      = -1;
 135                 dst_prev->flags        |= DST_HOST;
 136                 dst_prev->lastuse       = jiffies;
 137                 dst_prev->header_len    = header_len;
 138                 dst_prev->trailer_len   = trailer_len;
 139                 memcpy(&dst_prev->metrics, &rt->u.dst.metrics, sizeof(dst_prev->metrics));
 140                 dst_prev->path          = &rt->u.dst;
 141
 142                 /* Copy neighbout for reachability confirmation */
 143                 dst_prev->neighbour     = neigh_clone(rt->u.dst.neighbour);
 144                 dst_prev->input         = rt->u.dst.input;
 145                 dst_prev->output        = dst_prev->xfrm->type->output;
 146                 if (rt->peer)
 147                         atomic_inc(&rt->peer->refcnt);
 148                 x->u.rt.peer = rt->peer;
 149                 /* Sheit... I remember I did this right. Apparently,
 150                  * it was magically lost, so this code needs audit */
 151                 x->u.rt.rt_flags = rt0->rt_flags&(RTCF_BROADCAST|RTCF_MULTICAST|RTCF_LOCAL);
 152                 x->u.rt.rt_type = rt->rt_type;
 153                 x->u.rt.rt_src = rt0->rt_src;
 154                 x->u.rt.rt_dst = rt0->rt_dst;
 155                 x->u.rt.rt_gateway = rt->rt_gateway;
 156                 x->u.rt.rt_spec_dst = rt0->rt_spec_dst;
 157                 header_len -= x->u.dst.xfrm->props.header_len;
 158                 trailer_len -= x->u.dst.xfrm->props.trailer_len;
 159         }
 160         *dst_p = dst;
 161         return 0;
 162
 163 error:
 164         if (dst)
 165                 dst_free(dst);
 166         return err;
 167 }
 168
 169 static void
 170 _decode_session4(struct sk_buff *skb, struct flowi *fl)
 171 {
 172         struct iphdr *iph = skb->nh.iph;
 173         u8 *xprth = skb->nh.raw + iph->ihl*4;
 174
 175         memset(fl, 0, sizeof(struct flowi));
 176         if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
 177                 switch (iph->protocol) {
 178                 case IPPROTO_UDP:
 179                 case IPPROTO_TCP:
 180                 case IPPROTO_SCTP:
 181                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 182                                 u16 *ports = (u16 *)xprth;
 183
 184                                 fl->fl_ip_sport = ports[0];
 185                                 fl->fl_ip_dport = ports[1];
 186                         }
 187                         break;
 188
 189                 case IPPROTO_ESP:
 190                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 191                                 u32 *ehdr = (u32 *)xprth;
 192
 193                                 fl->fl_ipsec_spi = ehdr[0];
 194                         }
 195                         break;
 196
 197                 case IPPROTO_AH:
 198                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 199                                 u32 *ah_hdr = (u32*)xprth;
 200
 201                                 fl->fl_ipsec_spi = ah_hdr[1];
 202                         }
 203                         break;
 204
 205                 case IPPROTO_COMP:
 206                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 207                                 u16 *ipcomp_hdr = (u16 *)xprth;
 208
 209                                 fl->fl_ipsec_spi = ntohl(ntohs(ipcomp_hdr[1]));
 210                         }
 211                         break;
 212                 default:
 213                         fl->fl_ipsec_spi = 0;
 214                         break;
 215                 };
 216         }
 217         fl->proto = iph->protocol;
 218         fl->fl4_dst = iph->daddr;
 219         fl->fl4_src = iph->saddr;
 220 }
 221
 222 static inline int xfrm4_garbage_collect(void)
 223 {
 224         read_lock(&xfrm4_policy_afinfo.lock);
 225         xfrm4_policy_afinfo.garbage_collect();
 226         read_unlock(&xfrm4_policy_afinfo.lock);
 227         return (atomic_read(&xfrm4_dst_ops.entries) > xfrm4_dst_ops.gc_thresh*2);
 228 }
 229
 230 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
 231 {
 232         struct dst_entry *path = dst->path;
 233
 234         if (mtu < 68 + dst->header_len)
 235                 return;
 236
 237         path->ops->update_pmtu(path, mtu);
 238 }
 239
 240 struct dst_ops xfrm4_dst_ops = {
 241         .family =               AF_INET,
 242         .protocol =             __constant_htons(ETH_P_IP),
 243         .gc =                   xfrm4_garbage_collect,
 244         .update_pmtu =          xfrm4_update_pmtu,
 245         .gc_thresh =            1024,
 246         .entry_size =           sizeof(struct xfrm_dst),
 247 };
 248
 249 struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 250         .family =               AF_INET,
 251         .lock =                 RW_LOCK_UNLOCKED,
 252         .type_map =             &xfrm4_type_map,
 253         .dst_ops =              &xfrm4_dst_ops,
 254         .dst_lookup =           xfrm4_dst_lookup,
 255         .find_bundle =          __xfrm4_find_bundle,
 256         .bundle_create =        __xfrm4_bundle_create,
 257         .decode_session =       _decode_session4,
 258 };
 259
 260 void __init xfrm4_policy_init(void)
 261 {
 262         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 263 }
 264
 265 void __exit xfrm4_policy_fini(void)
 266 {
 267         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 268 }
 269
 270 void __init xfrm4_init(void)
 271 {
 272         xfrm4_state_init();
 273         xfrm4_policy_init();
 274 }
 275
 276 void __exit xfrm4_fini(void)
 277 {
 278         //xfrm4_input_fini();
 279         xfrm4_policy_fini();
 280         xfrm4_state_fini();
 281 }
 282