linux/net/ipv4/xfrm4_policy.c
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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
  18static struct dst_ops xfrm4_dst_ops;
  19static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
  20
  21static 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
  47static int xfrm4_get_saddr(struct net *net,
  48                           xfrm_address_t *saddr, xfrm_address_t *daddr)
  49{
  50        struct dst_entry *dst;
  51        struct rtable *rt;
  52
  53        dst = xfrm4_dst_lookup(net, 0, NULL, daddr);
  54        if (IS_ERR(dst))
  55                return -EHOSTUNREACH;
  56
  57        rt = (struct rtable *)dst;
  58        saddr->a4 = rt->rt_src;
  59        dst_release(dst);
  60        return 0;
  61}
  62
  63static struct dst_entry *
  64__xfrm4_find_bundle(struct flowi *fl, struct xfrm_policy *policy)
  65{
  66        struct dst_entry *dst;
  67
  68        read_lock_bh(&policy->lock);
  69        for (dst = policy->bundles; dst; dst = dst->next) {
  70                struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
  71                if (xdst->u.rt.fl.oif == fl->oif &&     /*XXX*/
  72                    xdst->u.rt.fl.fl4_dst == fl->fl4_dst &&
  73                    xdst->u.rt.fl.fl4_src == fl->fl4_src &&
  74                    xdst->u.rt.fl.fl4_tos == fl->fl4_tos &&
  75                    xfrm_bundle_ok(policy, xdst, fl, AF_INET, 0)) {
  76                        dst_clone(dst);
  77                        break;
  78                }
  79        }
  80        read_unlock_bh(&policy->lock);
  81        return dst;
  82}
  83
  84static int xfrm4_get_tos(struct flowi *fl)
  85{
  86        return fl->fl4_tos;
  87}
  88
  89static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst,
  90                           int nfheader_len)
  91{
  92        return 0;
  93}
  94
  95static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev)
  96{
  97        struct rtable *rt = (struct rtable *)xdst->route;
  98
  99        xdst->u.rt.fl = rt->fl;
 100
 101        xdst->u.dst.dev = dev;
 102        dev_hold(dev);
 103
 104        xdst->u.rt.idev = in_dev_get(dev);
 105        if (!xdst->u.rt.idev)
 106                return -ENODEV;
 107
 108        xdst->u.rt.peer = rt->peer;
 109        if (rt->peer)
 110                atomic_inc(&rt->peer->refcnt);
 111
 112        /* Sheit... I remember I did this right. Apparently,
 113         * it was magically lost, so this code needs audit */
 114        xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
 115                                              RTCF_LOCAL);
 116        xdst->u.rt.rt_type = rt->rt_type;
 117        xdst->u.rt.rt_src = rt->rt_src;
 118        xdst->u.rt.rt_dst = rt->rt_dst;
 119        xdst->u.rt.rt_gateway = rt->rt_gateway;
 120        xdst->u.rt.rt_spec_dst = rt->rt_spec_dst;
 121
 122        return 0;
 123}
 124
 125static void
 126_decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
 127{
 128        struct iphdr *iph = ip_hdr(skb);
 129        u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
 130
 131        memset(fl, 0, sizeof(struct flowi));
 132        if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
 133                switch (iph->protocol) {
 134                case IPPROTO_UDP:
 135                case IPPROTO_UDPLITE:
 136                case IPPROTO_TCP:
 137                case IPPROTO_SCTP:
 138                case IPPROTO_DCCP:
 139                        if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 140                                __be16 *ports = (__be16 *)xprth;
 141
 142                                fl->fl_ip_sport = ports[!!reverse];
 143                                fl->fl_ip_dport = ports[!reverse];
 144                        }
 145                        break;
 146
 147                case IPPROTO_ICMP:
 148                        if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 149                                u8 *icmp = xprth;
 150
 151                                fl->fl_icmp_type = icmp[0];
 152                                fl->fl_icmp_code = icmp[1];
 153                        }
 154                        break;
 155
 156                case IPPROTO_ESP:
 157                        if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 158                                __be32 *ehdr = (__be32 *)xprth;
 159
 160                                fl->fl_ipsec_spi = ehdr[0];
 161                        }
 162                        break;
 163
 164                case IPPROTO_AH:
 165                        if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 166                                __be32 *ah_hdr = (__be32*)xprth;
 167
 168                                fl->fl_ipsec_spi = ah_hdr[1];
 169                        }
 170                        break;
 171
 172                case IPPROTO_COMP:
 173                        if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 174                                __be16 *ipcomp_hdr = (__be16 *)xprth;
 175
 176                                fl->fl_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 177                        }
 178                        break;
 179                default:
 180                        fl->fl_ipsec_spi = 0;
 181                        break;
 182                }
 183        }
 184        fl->proto = iph->protocol;
 185        fl->fl4_dst = reverse ? iph->saddr : iph->daddr;
 186        fl->fl4_src = reverse ? iph->daddr : iph->saddr;
 187        fl->fl4_tos = iph->tos;
 188}
 189
 190static inline int xfrm4_garbage_collect(struct dst_ops *ops)
 191{
 192        xfrm4_policy_afinfo.garbage_collect(&init_net);
 193        return (atomic_read(&xfrm4_dst_ops.entries) > xfrm4_dst_ops.gc_thresh*2);
 194}
 195
 196static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
 197{
 198        struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 199        struct dst_entry *path = xdst->route;
 200
 201        path->ops->update_pmtu(path, mtu);
 202}
 203
 204static void xfrm4_dst_destroy(struct dst_entry *dst)
 205{
 206        struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 207
 208        if (likely(xdst->u.rt.idev))
 209                in_dev_put(xdst->u.rt.idev);
 210        if (likely(xdst->u.rt.peer))
 211                inet_putpeer(xdst->u.rt.peer);
 212        xfrm_dst_destroy(xdst);
 213}
 214
 215static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 216                             int unregister)
 217{
 218        struct xfrm_dst *xdst;
 219
 220        if (!unregister)
 221                return;
 222
 223        xdst = (struct xfrm_dst *)dst;
 224        if (xdst->u.rt.idev->dev == dev) {
 225                struct in_device *loopback_idev =
 226                        in_dev_get(dev_net(dev)->loopback_dev);
 227                BUG_ON(!loopback_idev);
 228
 229                do {
 230                        in_dev_put(xdst->u.rt.idev);
 231                        xdst->u.rt.idev = loopback_idev;
 232                        in_dev_hold(loopback_idev);
 233                        xdst = (struct xfrm_dst *)xdst->u.dst.child;
 234                } while (xdst->u.dst.xfrm);
 235
 236                __in_dev_put(loopback_idev);
 237        }
 238
 239        xfrm_dst_ifdown(dst, dev);
 240}
 241
 242static struct dst_ops xfrm4_dst_ops = {
 243        .family =               AF_INET,
 244        .protocol =             cpu_to_be16(ETH_P_IP),
 245        .gc =                   xfrm4_garbage_collect,
 246        .update_pmtu =          xfrm4_update_pmtu,
 247        .destroy =              xfrm4_dst_destroy,
 248        .ifdown =               xfrm4_dst_ifdown,
 249        .local_out =            __ip_local_out,
 250        .gc_thresh =            1024,
 251        .entries =              ATOMIC_INIT(0),
 252};
 253
 254static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 255        .family =               AF_INET,
 256        .dst_ops =              &xfrm4_dst_ops,
 257        .dst_lookup =           xfrm4_dst_lookup,
 258        .get_saddr =            xfrm4_get_saddr,
 259        .find_bundle =          __xfrm4_find_bundle,
 260        .decode_session =       _decode_session4,
 261        .get_tos =              xfrm4_get_tos,
 262        .init_path =            xfrm4_init_path,
 263        .fill_dst =             xfrm4_fill_dst,
 264};
 265
 266static void __init xfrm4_policy_init(void)
 267{
 268        xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 269}
 270
 271static void __exit xfrm4_policy_fini(void)
 272{
 273        xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 274}
 275
 276void __init xfrm4_init(void)
 277{
 278        xfrm4_state_init();
 279        xfrm4_policy_init();
 280}
 281
 282