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   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 <net/dst.h>
  15 #include <net/xfrm.h>
  16 #include <net/ip.h>
  17
  18 static struct dst_ops xfrm4_dst_ops;
  19 static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
  20
  21 static struct dst_entry *xfrm4_dst_lookup(int tos, xfrm_address_t *saddr,
  22                                           xfrm_address_t *daddr)
  23 {
  24         struct flowi fl = {
  25                 .nl_u = {
  26                         .ip4_u = {
  27                                 .tos = tos,
  28                                 .daddr = daddr->a4,
  29                         },
  30                 },
  31         };
  32         struct dst_entry *dst;
  33         struct rtable *rt;
  34         int err;
  35
  36         if (saddr)
  37                 fl.fl4_src = saddr->a4;
  38
  39         err = __ip_route_output_key(&rt, &fl);
  40         dst = &rt->u.dst;
  41         if (err)
  42                 dst = ERR_PTR(err);
  43         return dst;
  44 }
  45
  46 static int xfrm4_get_saddr(xfrm_address_t *saddr, xfrm_address_t *daddr)
  47 {
  48         struct dst_entry *dst;
  49         struct rtable *rt;
  50
  51         dst = xfrm4_dst_lookup(0, NULL, daddr);
  52         if (IS_ERR(dst))
  53                 return -EHOSTUNREACH;
  54
  55         rt = (struct rtable *)dst;
  56         saddr->a4 = rt->rt_src;
  57         dst_release(dst);
  58         return 0;
  59 }
  60
  61 static struct dst_entry *
  62 __xfrm4_find_bundle(struct flowi *fl, struct xfrm_policy *policy)
  63 {
  64         struct dst_entry *dst;
  65
  66         read_lock_bh(&policy->lock);
  67         for (dst = policy->bundles; dst; dst = dst->next) {
  68                 struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
  69                 if (xdst->u.rt.fl.oif == fl->oif &&     /*XXX*/
  70                     xdst->u.rt.fl.fl4_dst == fl->fl4_dst &&
  71                     xdst->u.rt.fl.fl4_src == fl->fl4_src &&
  72                     xdst->u.rt.fl.fl4_tos == fl->fl4_tos &&
  73                     xfrm_bundle_ok(policy, xdst, fl, AF_INET, 0)) {
  74                         dst_clone(dst);
  75                         break;
  76                 }
  77         }
  78         read_unlock_bh(&policy->lock);
  79         return dst;
  80 }
  81
  82 static int xfrm4_get_tos(struct flowi *fl)
  83 {
  84         return fl->fl4_tos;
  85 }
  86
  87 static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev)
  88 {
  89         struct rtable *rt = (struct rtable *)xdst->route;
  90
  91         xdst->u.rt.fl = rt->fl;
  92
  93         xdst->u.dst.dev = dev;
  94         dev_hold(dev);
  95
  96         xdst->u.rt.idev = in_dev_get(dev);
  97         if (!xdst->u.rt.idev)
  98                 return -ENODEV;
  99
 100         xdst->u.rt.peer = rt->peer;
 101         if (rt->peer)
 102                 atomic_inc(&rt->peer->refcnt);
 103
 104         /* Sheit... I remember I did this right. Apparently,
 105          * it was magically lost, so this code needs audit */
 106         xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
 107                                               RTCF_LOCAL);
 108         xdst->u.rt.rt_type = rt->rt_type;
 109         xdst->u.rt.rt_src = rt->rt_src;
 110         xdst->u.rt.rt_dst = rt->rt_dst;
 111         xdst->u.rt.rt_gateway = rt->rt_gateway;
 112         xdst->u.rt.rt_spec_dst = rt->rt_spec_dst;
 113
 114         return 0;
 115 }
 116
 117 static void
 118 _decode_session4(struct sk_buff *skb, struct flowi *fl)
 119 {
 120         struct iphdr *iph = ip_hdr(skb);
 121         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
 122
 123         memset(fl, 0, sizeof(struct flowi));
 124         if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
 125                 switch (iph->protocol) {
 126                 case IPPROTO_UDP:
 127                 case IPPROTO_UDPLITE:
 128                 case IPPROTO_TCP:
 129                 case IPPROTO_SCTP:
 130                 case IPPROTO_DCCP:
 131                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 132                                 __be16 *ports = (__be16 *)xprth;
 133
 134                                 fl->fl_ip_sport = ports[0];
 135                                 fl->fl_ip_dport = ports[1];
 136                         }
 137                         break;
 138
 139                 case IPPROTO_ICMP:
 140                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 141                                 u8 *icmp = xprth;
 142
 143                                 fl->fl_icmp_type = icmp[0];
 144                                 fl->fl_icmp_code = icmp[1];
 145                         }
 146                         break;
 147
 148                 case IPPROTO_ESP:
 149                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 150                                 __be32 *ehdr = (__be32 *)xprth;
 151
 152                                 fl->fl_ipsec_spi = ehdr[0];
 153                         }
 154                         break;
 155
 156                 case IPPROTO_AH:
 157                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 158                                 __be32 *ah_hdr = (__be32*)xprth;
 159
 160                                 fl->fl_ipsec_spi = ah_hdr[1];
 161                         }
 162                         break;
 163
 164                 case IPPROTO_COMP:
 165                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 166                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
 167
 168                                 fl->fl_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 169                         }
 170                         break;
 171                 default:
 172                         fl->fl_ipsec_spi = 0;
 173                         break;
 174                 }
 175         }
 176         fl->proto = iph->protocol;
 177         fl->fl4_dst = iph->daddr;
 178         fl->fl4_src = iph->saddr;
 179         fl->fl4_tos = iph->tos;
 180 }
 181
 182 static inline int xfrm4_garbage_collect(void)
 183 {
 184         xfrm4_policy_afinfo.garbage_collect();
 185         return (atomic_read(&xfrm4_dst_ops.entries) > xfrm4_dst_ops.gc_thresh*2);
 186 }
 187
 188 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
 189 {
 190         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 191         struct dst_entry *path = xdst->route;
 192
 193         path->ops->update_pmtu(path, mtu);
 194 }
 195
 196 static void xfrm4_dst_destroy(struct dst_entry *dst)
 197 {
 198         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 199
 200         if (likely(xdst->u.rt.idev))
 201                 in_dev_put(xdst->u.rt.idev);
 202         if (likely(xdst->u.rt.peer))
 203                 inet_putpeer(xdst->u.rt.peer);
 204         xfrm_dst_destroy(xdst);
 205 }
 206
 207 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 208                              int unregister)
 209 {
 210         struct xfrm_dst *xdst;
 211
 212         if (!unregister)
 213                 return;
 214
 215         xdst = (struct xfrm_dst *)dst;
 216         if (xdst->u.rt.idev->dev == dev) {
 217                 struct in_device *loopback_idev = in_dev_get(init_net.loopback_dev);
 218                 BUG_ON(!loopback_idev);
 219
 220                 do {
 221                         in_dev_put(xdst->u.rt.idev);
 222                         xdst->u.rt.idev = loopback_idev;
 223                         in_dev_hold(loopback_idev);
 224                         xdst = (struct xfrm_dst *)xdst->u.dst.child;
 225                 } while (xdst->u.dst.xfrm);
 226
 227                 __in_dev_put(loopback_idev);
 228         }
 229
 230         xfrm_dst_ifdown(dst, dev);
 231 }
 232
 233 static struct dst_ops xfrm4_dst_ops = {
 234         .family =               AF_INET,
 235         .protocol =             __constant_htons(ETH_P_IP),
 236         .gc =                   xfrm4_garbage_collect,
 237         .update_pmtu =          xfrm4_update_pmtu,
 238         .destroy =              xfrm4_dst_destroy,
 239         .ifdown =               xfrm4_dst_ifdown,
 240         .gc_thresh =            1024,
 241         .entry_size =           sizeof(struct xfrm_dst),
 242 };
 243
 244 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 245         .family =               AF_INET,
 246         .dst_ops =              &xfrm4_dst_ops,
 247         .dst_lookup =           xfrm4_dst_lookup,
 248         .get_saddr =            xfrm4_get_saddr,
 249         .find_bundle =          __xfrm4_find_bundle,
 250         .decode_session =       _decode_session4,
 251         .get_tos =              xfrm4_get_tos,
 252         .fill_dst =             xfrm4_fill_dst,
 253 };
 254
 255 static void __init xfrm4_policy_init(void)
 256 {
 257         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 258 }
 259
 260 static void __exit xfrm4_policy_fini(void)
 261 {
 262         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 263 }
 264
 265 void __init xfrm4_init(void)
 266 {
 267         xfrm4_state_init();
 268         xfrm4_policy_init();
 269 }
 270