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/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(struct net *net, int tos,
  22                                           xfrm_address_t *saddr,
  23                                           xfrm_address_t *daddr)
  24 {
  25         struct flowi fl = {
  26                 .nl_u = {
  27                         .ip4_u = {
  28                                 .tos = tos,
  29                                 .daddr = daddr->a4,
  30                         },
  31                 },
  32         };
  33         struct dst_entry *dst;
  34         struct rtable *rt;
  35         int err;
  36
  37         if (saddr)
  38                 fl.fl4_src = saddr->a4;
  39
  40         err = __ip_route_output_key(net, &rt, &fl);
  41         dst = &rt->u.dst;
  42         if (err)
  43                 dst = ERR_PTR(err);
  44         return dst;
  45 }
  46
  47 static int xfrm4_get_saddr(xfrm_address_t *saddr, xfrm_address_t *daddr)
  48 {
  49         struct dst_entry *dst;
  50         struct rtable *rt;
  51
  52         dst = xfrm4_dst_lookup(&init_net, 0, NULL, daddr);
  53         if (IS_ERR(dst))
  54                 return -EHOSTUNREACH;
  55
  56         rt = (struct rtable *)dst;
  57         saddr->a4 = rt->rt_src;
  58         dst_release(dst);
  59         return 0;
  60 }
  61
  62 static struct dst_entry *
  63 __xfrm4_find_bundle(struct flowi *fl, struct xfrm_policy *policy)
  64 {
  65         struct dst_entry *dst;
  66
  67         read_lock_bh(&policy->lock);
  68         for (dst = policy->bundles; dst; dst = dst->next) {
  69                 struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
  70                 if (xdst->u.rt.fl.oif == fl->oif &&     /*XXX*/
  71                     xdst->u.rt.fl.fl4_dst == fl->fl4_dst &&
  72                     xdst->u.rt.fl.fl4_src == fl->fl4_src &&
  73                     xdst->u.rt.fl.fl4_tos == fl->fl4_tos &&
  74                     xfrm_bundle_ok(policy, xdst, fl, AF_INET, 0)) {
  75                         dst_clone(dst);
  76                         break;
  77                 }
  78         }
  79         read_unlock_bh(&policy->lock);
  80         return dst;
  81 }
  82
  83 static int xfrm4_get_tos(struct flowi *fl)
  84 {
  85         return fl->fl4_tos;
  86 }
  87
  88 static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst,
  89                            int nfheader_len)
  90 {
  91         return 0;
  92 }
  93
  94 static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev)
  95 {
  96         struct rtable *rt = (struct rtable *)xdst->route;
  97
  98         xdst->u.rt.fl = rt->fl;
  99
 100         xdst->u.dst.dev = dev;
 101         dev_hold(dev);
 102
 103         xdst->u.rt.idev = in_dev_get(dev);
 104         if (!xdst->u.rt.idev)
 105                 return -ENODEV;
 106
 107         xdst->u.rt.peer = rt->peer;
 108         if (rt->peer)
 109                 atomic_inc(&rt->peer->refcnt);
 110
 111         /* Sheit... I remember I did this right. Apparently,
 112          * it was magically lost, so this code needs audit */
 113         xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
 114                                               RTCF_LOCAL);
 115         xdst->u.rt.rt_type = rt->rt_type;
 116         xdst->u.rt.rt_src = rt->rt_src;
 117         xdst->u.rt.rt_dst = rt->rt_dst;
 118         xdst->u.rt.rt_gateway = rt->rt_gateway;
 119         xdst->u.rt.rt_spec_dst = rt->rt_spec_dst;
 120
 121         return 0;
 122 }
 123
 124 static void
 125 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
 126 {
 127         struct iphdr *iph = ip_hdr(skb);
 128         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
 129
 130         memset(fl, 0, sizeof(struct flowi));
 131         if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
 132                 switch (iph->protocol) {
 133                 case IPPROTO_UDP:
 134                 case IPPROTO_UDPLITE:
 135                 case IPPROTO_TCP:
 136                 case IPPROTO_SCTP:
 137                 case IPPROTO_DCCP:
 138                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 139                                 __be16 *ports = (__be16 *)xprth;
 140
 141                                 fl->fl_ip_sport = ports[!!reverse];
 142                                 fl->fl_ip_dport = ports[!reverse];
 143                         }
 144                         break;
 145
 146                 case IPPROTO_ICMP:
 147                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 148                                 u8 *icmp = xprth;
 149
 150                                 fl->fl_icmp_type = icmp[0];
 151                                 fl->fl_icmp_code = icmp[1];
 152                         }
 153                         break;
 154
 155                 case IPPROTO_ESP:
 156                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 157                                 __be32 *ehdr = (__be32 *)xprth;
 158
 159                                 fl->fl_ipsec_spi = ehdr[0];
 160                         }
 161                         break;
 162
 163                 case IPPROTO_AH:
 164                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 165                                 __be32 *ah_hdr = (__be32*)xprth;
 166
 167                                 fl->fl_ipsec_spi = ah_hdr[1];
 168                         }
 169                         break;
 170
 171                 case IPPROTO_COMP:
 172                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 173                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
 174
 175                                 fl->fl_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 176                         }
 177                         break;
 178                 default:
 179                         fl->fl_ipsec_spi = 0;
 180                         break;
 181                 }
 182         }
 183         fl->proto = iph->protocol;
 184         fl->fl4_dst = reverse ? iph->saddr : iph->daddr;
 185         fl->fl4_src = reverse ? iph->daddr : iph->saddr;
 186         fl->fl4_tos = iph->tos;
 187 }
 188
 189 static inline int xfrm4_garbage_collect(struct dst_ops *ops)
 190 {
 191         xfrm4_policy_afinfo.garbage_collect(&init_net);
 192         return (atomic_read(&xfrm4_dst_ops.entries) > xfrm4_dst_ops.gc_thresh*2);
 193 }
 194
 195 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
 196 {
 197         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 198         struct dst_entry *path = xdst->route;
 199
 200         path->ops->update_pmtu(path, mtu);
 201 }
 202
 203 static void xfrm4_dst_destroy(struct dst_entry *dst)
 204 {
 205         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 206
 207         if (likely(xdst->u.rt.idev))
 208                 in_dev_put(xdst->u.rt.idev);
 209         if (likely(xdst->u.rt.peer))
 210                 inet_putpeer(xdst->u.rt.peer);
 211         xfrm_dst_destroy(xdst);
 212 }
 213
 214 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 215                              int unregister)
 216 {
 217         struct xfrm_dst *xdst;
 218
 219         if (!unregister)
 220                 return;
 221
 222         xdst = (struct xfrm_dst *)dst;
 223         if (xdst->u.rt.idev->dev == dev) {
 224                 struct in_device *loopback_idev =
 225                         in_dev_get(dev_net(dev)->loopback_dev);
 226                 BUG_ON(!loopback_idev);
 227
 228                 do {
 229                         in_dev_put(xdst->u.rt.idev);
 230                         xdst->u.rt.idev = loopback_idev;
 231                         in_dev_hold(loopback_idev);
 232                         xdst = (struct xfrm_dst *)xdst->u.dst.child;
 233                 } while (xdst->u.dst.xfrm);
 234
 235                 __in_dev_put(loopback_idev);
 236         }
 237
 238         xfrm_dst_ifdown(dst, dev);
 239 }
 240
 241 static struct dst_ops xfrm4_dst_ops = {
 242         .family =               AF_INET,
 243         .protocol =             __constant_htons(ETH_P_IP),
 244         .gc =                   xfrm4_garbage_collect,
 245         .update_pmtu =          xfrm4_update_pmtu,
 246         .destroy =              xfrm4_dst_destroy,
 247         .ifdown =               xfrm4_dst_ifdown,
 248         .local_out =            __ip_local_out,
 249         .gc_thresh =            1024,
 250         .entries =              ATOMIC_INIT(0),
 251 };
 252
 253 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 254         .family =               AF_INET,
 255         .dst_ops =              &xfrm4_dst_ops,
 256         .dst_lookup =           xfrm4_dst_lookup,
 257         .get_saddr =            xfrm4_get_saddr,
 258         .find_bundle =          __xfrm4_find_bundle,
 259         .decode_session =       _decode_session4,
 260         .get_tos =              xfrm4_get_tos,
 261         .init_path =            xfrm4_init_path,
 262         .fill_dst =             xfrm4_fill_dst,
 263 };
 264
 265 static void __init xfrm4_policy_init(void)
 266 {
 267         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 268 }
 269
 270 static void __exit xfrm4_policy_fini(void)
 271 {
 272         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 273 }
 274
 275 void __init xfrm4_init(void)
 276 {
 277         xfrm4_state_init();
 278         xfrm4_policy_init();
 279 }
 280