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         xdst->u.rt.rt_iif = fl4->flowi4_iif;
  83
  84         xdst->u.dst.dev = dev;
  85         dev_hold(dev);
  86
  87         /* Sheit... I remember I did this right. Apparently,
  88          * it was magically lost, so this code needs audit */
  89         xdst->u.rt.rt_is_input = rt->rt_is_input;
  90         xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
  91                                               RTCF_LOCAL);
  92         xdst->u.rt.rt_type = rt->rt_type;
  93         xdst->u.rt.rt_gateway = rt->rt_gateway;
  94         xdst->u.rt.rt_pmtu = rt->rt_pmtu;
  95         INIT_LIST_HEAD(&xdst->u.rt.rt_uncached);
  96
  97         return 0;
  98 }
  99
 100 static void
 101 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
 102 {
 103         const struct iphdr *iph = ip_hdr(skb);
 104         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
 105         struct flowi4 *fl4 = &fl->u.ip4;
 106
 107         memset(fl4, 0, sizeof(struct flowi4));
 108         fl4->flowi4_mark = skb->mark;
 109
 110         if (!ip_is_fragment(iph)) {
 111                 switch (iph->protocol) {
 112                 case IPPROTO_UDP:
 113                 case IPPROTO_UDPLITE:
 114                 case IPPROTO_TCP:
 115                 case IPPROTO_SCTP:
 116                 case IPPROTO_DCCP:
 117                         if (xprth + 4 < skb->data ||
 118                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
 119                                 __be16 *ports = (__be16 *)xprth;
 120
 121                                 fl4->fl4_sport = ports[!!reverse];
 122                                 fl4->fl4_dport = ports[!reverse];
 123                         }
 124                         break;
 125
 126                 case IPPROTO_ICMP:
 127                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 128                                 u8 *icmp = xprth;
 129
 130                                 fl4->fl4_icmp_type = icmp[0];
 131                                 fl4->fl4_icmp_code = icmp[1];
 132                         }
 133                         break;
 134
 135                 case IPPROTO_ESP:
 136                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 137                                 __be32 *ehdr = (__be32 *)xprth;
 138
 139                                 fl4->fl4_ipsec_spi = ehdr[0];
 140                         }
 141                         break;
 142
 143                 case IPPROTO_AH:
 144                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 145                                 __be32 *ah_hdr = (__be32 *)xprth;
 146
 147                                 fl4->fl4_ipsec_spi = ah_hdr[1];
 148                         }
 149                         break;
 150
 151                 case IPPROTO_COMP:
 152                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 153                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
 154
 155                                 fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 156                         }
 157                         break;
 158
 159                 case IPPROTO_GRE:
 160                         if (pskb_may_pull(skb, xprth + 12 - skb->data)) {
 161                                 __be16 *greflags = (__be16 *)xprth;
 162                                 __be32 *gre_hdr = (__be32 *)xprth;
 163
 164                                 if (greflags[0] & GRE_KEY) {
 165                                         if (greflags[0] & GRE_CSUM)
 166                                                 gre_hdr++;
 167                                         fl4->fl4_gre_key = gre_hdr[1];
 168                                 }
 169                         }
 170                         break;
 171
 172                 default:
 173                         fl4->fl4_ipsec_spi = 0;
 174                         break;
 175                 }
 176         }
 177         fl4->flowi4_proto = iph->protocol;
 178         fl4->daddr = reverse ? iph->saddr : iph->daddr;
 179         fl4->saddr = reverse ? iph->daddr : iph->saddr;
 180         fl4->flowi4_tos = iph->tos;
 181 }
 182
 183 static inline int xfrm4_garbage_collect(struct dst_ops *ops)
 184 {
 185         struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
 186
 187         xfrm4_policy_afinfo.garbage_collect(net);
 188         return (dst_entries_get_slow(ops) > ops->gc_thresh * 2);
 189 }
 190
 191 static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk,
 192                               struct sk_buff *skb, u32 mtu)
 193 {
 194         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 195         struct dst_entry *path = xdst->route;
 196
 197         path->ops->update_pmtu(path, sk, skb, mtu);
 198 }
 199
 200 static void xfrm4_redirect(struct dst_entry *dst, struct sock *sk,
 201                            struct sk_buff *skb)
 202 {
 203         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 204         struct dst_entry *path = xdst->route;
 205
 206         path->ops->redirect(path, sk, skb);
 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         xfrm_dst_destroy(xdst);
 216 }
 217
 218 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 219                              int unregister)
 220 {
 221         if (!unregister)
 222                 return;
 223
 224         xfrm_dst_ifdown(dst, dev);
 225 }
 226
 227 static struct dst_ops xfrm4_dst_ops = {
 228         .family =               AF_INET,
 229         .protocol =             cpu_to_be16(ETH_P_IP),
 230         .gc =                   xfrm4_garbage_collect,
 231         .update_pmtu =          xfrm4_update_pmtu,
 232         .redirect =             xfrm4_redirect,
 233         .cow_metrics =          dst_cow_metrics_generic,
 234         .destroy =              xfrm4_dst_destroy,
 235         .ifdown =               xfrm4_dst_ifdown,
 236         .local_out =            __ip_local_out,
 237         .gc_thresh =            1024,
 238 };
 239
 240 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 241         .family =               AF_INET,
 242         .dst_ops =              &xfrm4_dst_ops,
 243         .dst_lookup =           xfrm4_dst_lookup,
 244         .get_saddr =            xfrm4_get_saddr,
 245         .decode_session =       _decode_session4,
 246         .get_tos =              xfrm4_get_tos,
 247         .init_path =            xfrm4_init_path,
 248         .fill_dst =             xfrm4_fill_dst,
 249         .blackhole_route =      ipv4_blackhole_route,
 250 };
 251
 252 #ifdef CONFIG_SYSCTL
 253 static struct ctl_table xfrm4_policy_table[] = {
 254         {
 255                 .procname       = "xfrm4_gc_thresh",
 256                 .data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
 257                 .maxlen         = sizeof(int),
 258                 .mode           = 0644,
 259                 .proc_handler   = proc_dointvec,
 260         },
 261         { }
 262 };
 263
 264 static struct ctl_table_header *sysctl_hdr;
 265 #endif
 266
 267 static void __init xfrm4_policy_init(void)
 268 {
 269         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 270 }
 271
 272 static void __exit xfrm4_policy_fini(void)
 273 {
 274 #ifdef CONFIG_SYSCTL
 275         if (sysctl_hdr)
 276                 unregister_net_sysctl_table(sysctl_hdr);
 277 #endif
 278         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 279 }
 280
 281 void __init xfrm4_init(int rt_max_size)
 282 {
 283         /*
 284          * Select a default value for the gc_thresh based on the main route
 285          * table hash size.  It seems to me the worst case scenario is when
 286          * we have ipsec operating in transport mode, in which we create a
 287          * dst_entry per socket.  The xfrm gc algorithm starts trying to remove
 288          * entries at gc_thresh, and prevents new allocations as 2*gc_thresh
 289          * so lets set an initial xfrm gc_thresh value at the rt_max_size/2.
 290          * That will let us store an ipsec connection per route table entry,
 291          * and start cleaning when were 1/2 full
 292          */
 293         xfrm4_dst_ops.gc_thresh = rt_max_size/2;
 294         dst_entries_init(&xfrm4_dst_ops);
 295
 296         xfrm4_state_init();
 297         xfrm4_policy_init();
 298 #ifdef CONFIG_SYSCTL
 299         sysctl_hdr = register_net_sysctl(&init_net, "net/ipv4",
 300                                          xfrm4_policy_table);
 301 #endif
 302 }
 303