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