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 <linux/if_tunnel.h>
  15 #include <net/dst.h>
  16 #include <net/xfrm.h>
  17 #include <net/ip.h>
  18
  19 static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
  20
  21 static struct dst_entry *__xfrm4_dst_lookup(struct net *net, struct flowi4 *fl4,
  22                                             int tos,
  23                                             const xfrm_address_t *saddr,
  24                                             const xfrm_address_t *daddr)
  25 {
  26         struct rtable *rt;
  27
  28         memset(fl4, 0, sizeof(*fl4));
  29         fl4->daddr = daddr->a4;
  30         fl4->flowi4_tos = tos;
  31         if (saddr)
  32                 fl4->saddr = saddr->a4;
  33
  34         rt = __ip_route_output_key(net, fl4);
  35         if (!IS_ERR(rt))
  36                 return &rt->dst;
  37
  38         return ERR_CAST(rt);
  39 }
  40
  41 static struct dst_entry *xfrm4_dst_lookup(struct net *net, int tos,
  42                                           const xfrm_address_t *saddr,
  43                                           const xfrm_address_t *daddr)
  44 {
  45         struct flowi4 fl4;
  46
  47         return __xfrm4_dst_lookup(net, &fl4, tos, saddr, daddr);
  48 }
  49
  50 static int xfrm4_get_saddr(struct net *net,
  51                            xfrm_address_t *saddr, xfrm_address_t *daddr)
  52 {
  53         struct dst_entry *dst;
  54         struct flowi4 fl4;
  55
  56         dst = __xfrm4_dst_lookup(net, &fl4, 0, NULL, daddr);
  57         if (IS_ERR(dst))
  58                 return -EHOSTUNREACH;
  59
  60         saddr->a4 = fl4.saddr;
  61         dst_release(dst);
  62         return 0;
  63 }
  64
  65 static int xfrm4_get_tos(const struct flowi *fl)
  66 {
  67         return IPTOS_RT_MASK & fl->u.ip4.flowi4_tos; /* Strip ECN bits */
  68 }
  69
  70 static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst,
  71                            int nfheader_len)
  72 {
  73         return 0;
  74 }
  75
  76 static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
  77                           const struct flowi *fl)
  78 {
  79         struct rtable *rt = (struct rtable *)xdst->route;
  80         const struct flowi4 *fl4 = &fl->u.ip4;
  81
  82         rt->rt_key_dst = fl4->daddr;
  83         rt->rt_key_src = fl4->saddr;
  84         rt->rt_key_tos = fl4->flowi4_tos;
  85         rt->rt_route_iif = fl4->flowi4_iif;
  86         rt->rt_iif = fl4->flowi4_iif;
  87         rt->rt_oif = fl4->flowi4_oif;
  88         rt->rt_mark = fl4->flowi4_mark;
  89
  90         xdst->u.dst.dev = dev;
  91         dev_hold(dev);
  92
  93         xdst->u.rt.peer = rt->peer;
  94         if (rt->peer)
  95                 atomic_inc(&rt->peer->refcnt);
  96
  97         /* Sheit... I remember I did this right. Apparently,
  98          * it was magically lost, so this code needs audit */
  99         xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
 100                                               RTCF_LOCAL);
 101         xdst->u.rt.rt_type = rt->rt_type;
 102         xdst->u.rt.rt_src = rt->rt_src;
 103         xdst->u.rt.rt_dst = rt->rt_dst;
 104         xdst->u.rt.rt_gateway = rt->rt_gateway;
 105         xdst->u.rt.rt_spec_dst = rt->rt_spec_dst;
 106
 107         return 0;
 108 }
 109
 110 static void
 111 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
 112 {
 113         const struct iphdr *iph = ip_hdr(skb);
 114         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
 115         struct flowi4 *fl4 = &fl->u.ip4;
 116
 117         memset(fl4, 0, sizeof(struct flowi4));
 118         fl4->flowi4_mark = skb->mark;
 119
 120         if (!ip_is_fragment(iph)) {
 121                 switch (iph->protocol) {
 122                 case IPPROTO_UDP:
 123                 case IPPROTO_UDPLITE:
 124                 case IPPROTO_TCP:
 125                 case IPPROTO_SCTP:
 126                 case IPPROTO_DCCP:
 127                         if (xprth + 4 < skb->data ||
 128                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
 129                                 __be16 *ports = (__be16 *)xprth;
 130
 131                                 fl4->fl4_sport = ports[!!reverse];
 132                                 fl4->fl4_dport = ports[!reverse];
 133                         }
 134                         break;
 135
 136                 case IPPROTO_ICMP:
 137                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 138                                 u8 *icmp = xprth;
 139
 140                                 fl4->fl4_icmp_type = icmp[0];
 141                                 fl4->fl4_icmp_code = icmp[1];
 142                         }
 143                         break;
 144
 145                 case IPPROTO_ESP:
 146                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 147                                 __be32 *ehdr = (__be32 *)xprth;
 148
 149                                 fl4->fl4_ipsec_spi = ehdr[0];
 150                         }
 151                         break;
 152
 153                 case IPPROTO_AH:
 154                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 155                                 __be32 *ah_hdr = (__be32*)xprth;
 156
 157                                 fl4->fl4_ipsec_spi = ah_hdr[1];
 158                         }
 159                         break;
 160
 161                 case IPPROTO_COMP:
 162                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 163                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
 164
 165                                 fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 166                         }
 167                         break;
 168
 169                 case IPPROTO_GRE:
 170                         if (pskb_may_pull(skb, xprth + 12 - skb->data)) {
 171                                 __be16 *greflags = (__be16 *)xprth;
 172                                 __be32 *gre_hdr = (__be32 *)xprth;
 173
 174                                 if (greflags[0] & GRE_KEY) {
 175                                         if (greflags[0] & GRE_CSUM)
 176                                                 gre_hdr++;
 177                                         fl4->fl4_gre_key = gre_hdr[1];
 178                                 }
 179                         }
 180                         break;
 181
 182                 default:
 183                         fl4->fl4_ipsec_spi = 0;
 184                         break;
 185                 }
 186         }
 187         fl4->flowi4_proto = iph->protocol;
 188         fl4->daddr = reverse ? iph->saddr : iph->daddr;
 189         fl4->saddr = reverse ? iph->daddr : iph->saddr;
 190         fl4->flowi4_tos = iph->tos;
 191 }
 192
 193 static inline int xfrm4_garbage_collect(struct dst_ops *ops)
 194 {
 195         struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
 196
 197         xfrm4_policy_afinfo.garbage_collect(net);
 198         return (dst_entries_get_slow(ops) > ops->gc_thresh * 2);
 199 }
 200
 201 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
 202 {
 203         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 204         struct dst_entry *path = xdst->route;
 205
 206         path->ops->update_pmtu(path, mtu);
 207 }
 208
 209 static void xfrm4_dst_destroy(struct dst_entry *dst)
 210 {
 211         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 212
 213         dst_destroy_metrics_generic(dst);
 214
 215         if (likely(xdst->u.rt.peer))
 216                 inet_putpeer(xdst->u.rt.peer);
 217
 218         xfrm_dst_destroy(xdst);
 219 }
 220
 221 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 222                              int unregister)
 223 {
 224         if (!unregister)
 225                 return;
 226
 227         xfrm_dst_ifdown(dst, dev);
 228 }
 229
 230 static struct dst_ops xfrm4_dst_ops = {
 231         .family =               AF_INET,
 232         .protocol =             cpu_to_be16(ETH_P_IP),
 233         .gc =                   xfrm4_garbage_collect,
 234         .update_pmtu =          xfrm4_update_pmtu,
 235         .cow_metrics =          dst_cow_metrics_generic,
 236         .destroy =              xfrm4_dst_destroy,
 237         .ifdown =               xfrm4_dst_ifdown,
 238         .local_out =            __ip_local_out,
 239         .gc_thresh =            1024,
 240 };
 241
 242 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 243         .family =               AF_INET,
 244         .dst_ops =              &xfrm4_dst_ops,
 245         .dst_lookup =           xfrm4_dst_lookup,
 246         .get_saddr =            xfrm4_get_saddr,
 247         .decode_session =       _decode_session4,
 248         .get_tos =              xfrm4_get_tos,
 249         .init_path =            xfrm4_init_path,
 250         .fill_dst =             xfrm4_fill_dst,
 251         .blackhole_route =      ipv4_blackhole_route,
 252 };
 253
 254 #ifdef CONFIG_SYSCTL
 255 static struct ctl_table xfrm4_policy_table[] = {
 256         {
 257                 .procname       = "xfrm4_gc_thresh",
 258                 .data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
 259                 .maxlen         = sizeof(int),
 260                 .mode           = 0644,
 261                 .proc_handler   = proc_dointvec,
 262         },
 263         { }
 264 };
 265
 266 static struct ctl_table_header *sysctl_hdr;
 267 #endif
 268
 269 static void __init xfrm4_policy_init(void)
 270 {
 271         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 272 }
 273
 274 static void __exit xfrm4_policy_fini(void)
 275 {
 276 #ifdef CONFIG_SYSCTL
 277         if (sysctl_hdr)
 278                 unregister_net_sysctl_table(sysctl_hdr);
 279 #endif
 280         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 281 }
 282
 283 void __init xfrm4_init(int rt_max_size)
 284 {
 285         /*
 286          * Select a default value for the gc_thresh based on the main route
 287          * table hash size.  It seems to me the worst case scenario is when
 288          * we have ipsec operating in transport mode, in which we create a
 289          * dst_entry per socket.  The xfrm gc algorithm starts trying to remove
 290          * entries at gc_thresh, and prevents new allocations as 2*gc_thresh
 291          * so lets set an initial xfrm gc_thresh value at the rt_max_size/2.
 292          * That will let us store an ipsec connection per route table entry,
 293          * and start cleaning when were 1/2 full
 294          */
 295         xfrm4_dst_ops.gc_thresh = rt_max_size/2;
 296         dst_entries_init(&xfrm4_dst_ops);
 297
 298         xfrm4_state_init();
 299         xfrm4_policy_init();
 300 #ifdef CONFIG_SYSCTL
 301         sysctl_hdr = register_net_sysctl_table(&init_net, net_ipv4_ctl_path,
 302                                                 xfrm4_policy_table);
 303 #endif
 304 }
 305