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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 xfrm_policy_afinfo xfrm4_policy_afinfo;
  19
  20 static struct dst_entry *xfrm4_dst_lookup(struct net *net, int tos,
  21                                           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(net, &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(struct net *net,
  47                            xfrm_address_t *saddr, xfrm_address_t *daddr)
  48 {
  49         struct dst_entry *dst;
  50         struct rtable *rt;
  51
  52         dst = xfrm4_dst_lookup(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 int xfrm4_get_tos(struct flowi *fl)
  63 {
  64         return fl->fl4_tos;
  65 }
  66
  67 static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst,
  68                            int nfheader_len)
  69 {
  70         return 0;
  71 }
  72
  73 static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
  74                           struct flowi *fl)
  75 {
  76         struct rtable *rt = (struct rtable *)xdst->route;
  77
  78         xdst->u.rt.fl = *fl;
  79
  80         xdst->u.dst.dev = dev;
  81         dev_hold(dev);
  82
  83         xdst->u.rt.idev = in_dev_get(dev);
  84         if (!xdst->u.rt.idev)
  85                 return -ENODEV;
  86
  87         xdst->u.rt.peer = rt->peer;
  88         if (rt->peer)
  89                 atomic_inc(&rt->peer->refcnt);
  90
  91         /* Sheit... I remember I did this right. Apparently,
  92          * it was magically lost, so this code needs audit */
  93         xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
  94                                               RTCF_LOCAL);
  95         xdst->u.rt.rt_type = rt->rt_type;
  96         xdst->u.rt.rt_src = rt->rt_src;
  97         xdst->u.rt.rt_dst = rt->rt_dst;
  98         xdst->u.rt.rt_gateway = rt->rt_gateway;
  99         xdst->u.rt.rt_spec_dst = rt->rt_spec_dst;
 100
 101         return 0;
 102 }
 103
 104 static void
 105 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
 106 {
 107         struct iphdr *iph = ip_hdr(skb);
 108         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
 109
 110         memset(fl, 0, sizeof(struct flowi));
 111         if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
 112                 switch (iph->protocol) {
 113                 case IPPROTO_UDP:
 114                 case IPPROTO_UDPLITE:
 115                 case IPPROTO_TCP:
 116                 case IPPROTO_SCTP:
 117                 case IPPROTO_DCCP:
 118                         if (xprth + 4 < skb->data ||
 119                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
 120                                 __be16 *ports = (__be16 *)xprth;
 121
 122                                 fl->fl_ip_sport = ports[!!reverse];
 123                                 fl->fl_ip_dport = ports[!reverse];
 124                         }
 125                         break;
 126
 127                 case IPPROTO_ICMP:
 128                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 129                                 u8 *icmp = xprth;
 130
 131                                 fl->fl_icmp_type = icmp[0];
 132                                 fl->fl_icmp_code = icmp[1];
 133                         }
 134                         break;
 135
 136                 case IPPROTO_ESP:
 137                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 138                                 __be32 *ehdr = (__be32 *)xprth;
 139
 140                                 fl->fl_ipsec_spi = ehdr[0];
 141                         }
 142                         break;
 143
 144                 case IPPROTO_AH:
 145                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 146                                 __be32 *ah_hdr = (__be32*)xprth;
 147
 148                                 fl->fl_ipsec_spi = ah_hdr[1];
 149                         }
 150                         break;
 151
 152                 case IPPROTO_COMP:
 153                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 154                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
 155
 156                                 fl->fl_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 157                         }
 158                         break;
 159                 default:
 160                         fl->fl_ipsec_spi = 0;
 161                         break;
 162                 }
 163         }
 164         fl->proto = iph->protocol;
 165         fl->fl4_dst = reverse ? iph->saddr : iph->daddr;
 166         fl->fl4_src = reverse ? iph->daddr : iph->saddr;
 167         fl->fl4_tos = iph->tos;
 168 }
 169
 170 static inline int xfrm4_garbage_collect(struct dst_ops *ops)
 171 {
 172         struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
 173
 174         xfrm4_policy_afinfo.garbage_collect(net);
 175         return (atomic_read(&ops->entries) > ops->gc_thresh * 2);
 176 }
 177
 178 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
 179 {
 180         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 181         struct dst_entry *path = xdst->route;
 182
 183         path->ops->update_pmtu(path, mtu);
 184 }
 185
 186 static void xfrm4_dst_destroy(struct dst_entry *dst)
 187 {
 188         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 189
 190         if (likely(xdst->u.rt.idev))
 191                 in_dev_put(xdst->u.rt.idev);
 192         if (likely(xdst->u.rt.peer))
 193                 inet_putpeer(xdst->u.rt.peer);
 194         xfrm_dst_destroy(xdst);
 195 }
 196
 197 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 198                              int unregister)
 199 {
 200         struct xfrm_dst *xdst;
 201
 202         if (!unregister)
 203                 return;
 204
 205         xdst = (struct xfrm_dst *)dst;
 206         if (xdst->u.rt.idev->dev == dev) {
 207                 struct in_device *loopback_idev =
 208                         in_dev_get(dev_net(dev)->loopback_dev);
 209                 BUG_ON(!loopback_idev);
 210
 211                 do {
 212                         in_dev_put(xdst->u.rt.idev);
 213                         xdst->u.rt.idev = loopback_idev;
 214                         in_dev_hold(loopback_idev);
 215                         xdst = (struct xfrm_dst *)xdst->u.dst.child;
 216                 } while (xdst->u.dst.xfrm);
 217
 218                 __in_dev_put(loopback_idev);
 219         }
 220
 221         xfrm_dst_ifdown(dst, dev);
 222 }
 223
 224 static struct dst_ops xfrm4_dst_ops = {
 225         .family =               AF_INET,
 226         .protocol =             cpu_to_be16(ETH_P_IP),
 227         .gc =                   xfrm4_garbage_collect,
 228         .update_pmtu =          xfrm4_update_pmtu,
 229         .destroy =              xfrm4_dst_destroy,
 230         .ifdown =               xfrm4_dst_ifdown,
 231         .local_out =            __ip_local_out,
 232         .gc_thresh =            1024,
 233         .entries =              ATOMIC_INIT(0),
 234 };
 235
 236 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 237         .family =               AF_INET,
 238         .dst_ops =              &xfrm4_dst_ops,
 239         .dst_lookup =           xfrm4_dst_lookup,
 240         .get_saddr =            xfrm4_get_saddr,
 241         .decode_session =       _decode_session4,
 242         .get_tos =              xfrm4_get_tos,
 243         .init_path =            xfrm4_init_path,
 244         .fill_dst =             xfrm4_fill_dst,
 245 };
 246
 247 #ifdef CONFIG_SYSCTL
 248 static struct ctl_table xfrm4_policy_table[] = {
 249         {
 250                 .procname       = "xfrm4_gc_thresh",
 251                 .data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
 252                 .maxlen         = sizeof(int),
 253                 .mode           = 0644,
 254                 .proc_handler   = proc_dointvec,
 255         },
 256         { }
 257 };
 258
 259 static struct ctl_table_header *sysctl_hdr;
 260 #endif
 261
 262 static void __init xfrm4_policy_init(void)
 263 {
 264         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 265 }
 266
 267 static void __exit xfrm4_policy_fini(void)
 268 {
 269 #ifdef CONFIG_SYSCTL
 270         if (sysctl_hdr)
 271                 unregister_net_sysctl_table(sysctl_hdr);
 272 #endif
 273         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 274 }
 275
 276 void __init xfrm4_init(int rt_max_size)
 277 {
 278         /*
 279          * Select a default value for the gc_thresh based on the main route
 280          * table hash size.  It seems to me the worst case scenario is when
 281          * we have ipsec operating in transport mode, in which we create a
 282          * dst_entry per socket.  The xfrm gc algorithm starts trying to remove
 283          * entries at gc_thresh, and prevents new allocations as 2*gc_thresh
 284          * so lets set an initial xfrm gc_thresh value at the rt_max_size/2.
 285          * That will let us store an ipsec connection per route table entry,
 286          * and start cleaning when were 1/2 full
 287          */
 288         xfrm4_dst_ops.gc_thresh = rt_max_size/2;
 289
 290         xfrm4_state_init();
 291         xfrm4_policy_init();
 292 #ifdef CONFIG_SYSCTL
 293         sysctl_hdr = register_net_sysctl_table(&init_net, net_ipv4_ctl_path,
 294                                                 xfrm4_policy_table);
 295 #endif
 296 }
 297