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