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 static struct dst_ops xfrm4_dst_ops;
  16 static 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 static struct dst_entry *
  26 __xfrm4_find_bundle(struct flowi *fl, struct xfrm_policy *policy)
  27 {
  28         struct dst_entry *dst;
  29
  30         read_lock_bh(&policy->lock);
  31         for (dst = policy->bundles; dst; dst = dst->next) {
  32                 struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
  33                 if (xdst->u.rt.fl.oif == fl->oif &&     /*XXX*/
  34                     xdst->u.rt.fl.fl4_dst == fl->fl4_dst &&
  35                     xdst->u.rt.fl.fl4_src == fl->fl4_src &&
  36                     xfrm_bundle_ok(xdst, fl, AF_INET)) {
  37                         dst_clone(dst);
  38                         break;
  39                 }
  40         }
  41         read_unlock_bh(&policy->lock);
  42         return dst;
  43 }
  44
  45 /* Allocate chain of dst_entry's, attach known xfrm's, calculate
  46  * all the metrics... Shortly, bundle a bundle.
  47  */
  48
  49 static int
  50 __xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int nx,
  51                       struct flowi *fl, struct dst_entry **dst_p)
  52 {
  53         struct dst_entry *dst, *dst_prev;
  54         struct rtable *rt0 = (struct rtable*)(*dst_p);
  55         struct rtable *rt = rt0;
  56         u32 remote = fl->fl4_dst;
  57         u32 local  = fl->fl4_src;
  58         struct flowi fl_tunnel = {
  59                 .nl_u = {
  60                         .ip4_u = {
  61                                 .saddr = local,
  62                                 .daddr = remote
  63                         }
  64                 }
  65         };
  66         int i;
  67         int err;
  68         int header_len = 0;
  69         int trailer_len = 0;
  70
  71         dst = dst_prev = NULL;
  72         dst_hold(&rt->u.dst);
  73
  74         for (i = 0; i < nx; i++) {
  75                 struct dst_entry *dst1 = dst_alloc(&xfrm4_dst_ops);
  76                 struct xfrm_dst *xdst;
  77                 int tunnel = 0;
  78
  79                 if (unlikely(dst1 == NULL)) {
  80                         err = -ENOBUFS;
  81                         dst_release(&rt->u.dst);
  82                         goto error;
  83                 }
  84
  85                 if (!dst)
  86                         dst = dst1;
  87                 else {
  88                         dst_prev->child = dst1;
  89                         dst1->flags |= DST_NOHASH;
  90                         dst_clone(dst1);
  91                 }
  92
  93                 xdst = (struct xfrm_dst *)dst1;
  94                 xdst->route = &rt->u.dst;
  95
  96                 dst1->next = dst_prev;
  97                 dst_prev = dst1;
  98                 if (xfrm[i]->props.mode) {
  99                         remote = xfrm[i]->id.daddr.a4;
 100                         local  = xfrm[i]->props.saddr.a4;
 101                         tunnel = 1;
 102                 }
 103                 header_len += xfrm[i]->props.header_len;
 104                 trailer_len += xfrm[i]->props.trailer_len;
 105
 106                 if (tunnel) {
 107                         fl_tunnel.fl4_src = local;
 108                         fl_tunnel.fl4_dst = remote;
 109                         err = xfrm_dst_lookup((struct xfrm_dst **)&rt,
 110                                               &fl_tunnel, AF_INET);
 111                         if (err)
 112                                 goto error;
 113                 } else
 114                         dst_hold(&rt->u.dst);
 115         }
 116
 117         dst_prev->child = &rt->u.dst;
 118         dst->path = &rt->u.dst;
 119
 120         *dst_p = dst;
 121         dst = dst_prev;
 122
 123         dst_prev = *dst_p;
 124         i = 0;
 125         for (; dst_prev != &rt->u.dst; dst_prev = dst_prev->child) {
 126                 struct xfrm_dst *x = (struct xfrm_dst*)dst_prev;
 127                 x->u.rt.fl = *fl;
 128
 129                 dst_prev->xfrm = xfrm[i++];
 130                 dst_prev->dev = rt->u.dst.dev;
 131                 if (rt->u.dst.dev)
 132                         dev_hold(rt->u.dst.dev);
 133                 dst_prev->obsolete      = -1;
 134                 dst_prev->flags        |= DST_HOST;
 135                 dst_prev->lastuse       = jiffies;
 136                 dst_prev->header_len    = header_len;
 137                 dst_prev->trailer_len   = trailer_len;
 138                 memcpy(&dst_prev->metrics, &x->route->metrics, sizeof(dst_prev->metrics));
 139
 140                 /* Copy neighbout for reachability confirmation */
 141                 dst_prev->neighbour     = neigh_clone(rt->u.dst.neighbour);
 142                 dst_prev->input         = rt->u.dst.input;
 143                 dst_prev->output        = xfrm4_output;
 144                 if (rt->peer)
 145                         atomic_inc(&rt->peer->refcnt);
 146                 x->u.rt.peer = rt->peer;
 147                 /* Sheit... I remember I did this right. Apparently,
 148                  * it was magically lost, so this code needs audit */
 149                 x->u.rt.rt_flags = rt0->rt_flags&(RTCF_BROADCAST|RTCF_MULTICAST|RTCF_LOCAL);
 150                 x->u.rt.rt_type = rt->rt_type;
 151                 x->u.rt.rt_src = rt0->rt_src;
 152                 x->u.rt.rt_dst = rt0->rt_dst;
 153                 x->u.rt.rt_gateway = rt->rt_gateway;
 154                 x->u.rt.rt_spec_dst = rt0->rt_spec_dst;
 155                 header_len -= x->u.dst.xfrm->props.header_len;
 156                 trailer_len -= x->u.dst.xfrm->props.trailer_len;
 157         }
 158
 159         xfrm_init_pmtu(dst);
 160         return 0;
 161
 162 error:
 163         if (dst)
 164                 dst_free(dst);
 165         return err;
 166 }
 167
 168 static void
 169 _decode_session4(struct sk_buff *skb, struct flowi *fl)
 170 {
 171         struct iphdr *iph = skb->nh.iph;
 172         u8 *xprth = skb->nh.raw + iph->ihl*4;
 173
 174         memset(fl, 0, sizeof(struct flowi));
 175         if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
 176                 switch (iph->protocol) {
 177                 case IPPROTO_UDP:
 178                 case IPPROTO_TCP:
 179                 case IPPROTO_SCTP:
 180                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 181                                 u16 *ports = (u16 *)xprth;
 182
 183                                 fl->fl_ip_sport = ports[0];
 184                                 fl->fl_ip_dport = ports[1];
 185                         }
 186                         break;
 187
 188                 case IPPROTO_ICMP:
 189                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 190                                 u8 *icmp = xprth;
 191
 192                                 fl->fl_icmp_type = icmp[0];
 193                                 fl->fl_icmp_code = icmp[1];
 194                         }
 195                         break;
 196
 197                 case IPPROTO_ESP:
 198                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 199                                 u32 *ehdr = (u32 *)xprth;
 200
 201                                 fl->fl_ipsec_spi = ehdr[0];
 202                         }
 203                         break;
 204
 205                 case IPPROTO_AH:
 206                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 207                                 u32 *ah_hdr = (u32*)xprth;
 208
 209                                 fl->fl_ipsec_spi = ah_hdr[1];
 210                         }
 211                         break;
 212
 213                 case IPPROTO_COMP:
 214                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 215                                 u16 *ipcomp_hdr = (u16 *)xprth;
 216
 217                                 fl->fl_ipsec_spi = ntohl(ntohs(ipcomp_hdr[1]));
 218                         }
 219                         break;
 220                 default:
 221                         fl->fl_ipsec_spi = 0;
 222                         break;
 223                 };
 224         }
 225         fl->proto = iph->protocol;
 226         fl->fl4_dst = iph->daddr;
 227         fl->fl4_src = iph->saddr;
 228 }
 229
 230 static inline int xfrm4_garbage_collect(void)
 231 {
 232         read_lock(&xfrm4_policy_afinfo.lock);
 233         xfrm4_policy_afinfo.garbage_collect();
 234         read_unlock(&xfrm4_policy_afinfo.lock);
 235         return (atomic_read(&xfrm4_dst_ops.entries) > xfrm4_dst_ops.gc_thresh*2);
 236 }
 237
 238 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
 239 {
 240         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 241         struct dst_entry *path = xdst->route;
 242
 243         path->ops->update_pmtu(path, mtu);
 244 }
 245
 246 static struct dst_ops xfrm4_dst_ops = {
 247         .family =               AF_INET,
 248         .protocol =             __constant_htons(ETH_P_IP),
 249         .gc =                   xfrm4_garbage_collect,
 250         .update_pmtu =          xfrm4_update_pmtu,
 251         .gc_thresh =            1024,
 252         .entry_size =           sizeof(struct xfrm_dst),
 253 };
 254
 255 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 256         .family =               AF_INET,
 257         .lock =                 RW_LOCK_UNLOCKED,
 258         .type_map =             &xfrm4_type_map,
 259         .dst_ops =              &xfrm4_dst_ops,
 260         .dst_lookup =           xfrm4_dst_lookup,
 261         .find_bundle =          __xfrm4_find_bundle,
 262         .bundle_create =        __xfrm4_bundle_create,
 263         .decode_session =       _decode_session4,
 264 };
 265
 266 static void __init xfrm4_policy_init(void)
 267 {
 268         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 269 }
 270
 271 static void __exit xfrm4_policy_fini(void)
 272 {
 273         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 274 }
 275
 276 void __init xfrm4_init(void)
 277 {
 278         xfrm4_state_init();
 279         xfrm4_policy_init();
 280 }
 281