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_route_iif = fl4->flowi4_iif;
  83         xdst->u.rt.rt_iif = fl4->flowi4_iif;
  84         xdst->u.rt.rt_oif = fl4->flowi4_oif;
  85         xdst->u.rt.rt_mark = fl4->flowi4_mark;
  86
  87         xdst->u.dst.dev = dev;
  88         dev_hold(dev);
  89
  90         /* Sheit... I remember I did this right. Apparently,
  91          * it was magically lost, so this code needs audit */
  92         xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
  93                                               RTCF_LOCAL);
  94         xdst->u.rt.rt_type = rt->rt_type;
  95         xdst->u.rt.rt_src = rt->rt_src;
  96         xdst->u.rt.rt_dst = rt->rt_dst;
  97         xdst->u.rt.rt_gateway = rt->rt_gateway;
  98         xdst->u.rt.rt_pmtu = rt->rt_pmtu;
  99
 100         return 0;
 101 }
 102
 103 static void
 104 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
 105 {
 106         const struct iphdr *iph = ip_hdr(skb);
 107         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
 108         struct flowi4 *fl4 = &fl->u.ip4;
 109
 110         memset(fl4, 0, sizeof(struct flowi4));
 111         fl4->flowi4_mark = skb->mark;
 112
 113         if (!ip_is_fragment(iph)) {
 114                 switch (iph->protocol) {
 115                 case IPPROTO_UDP:
 116                 case IPPROTO_UDPLITE:
 117                 case IPPROTO_TCP:
 118                 case IPPROTO_SCTP:
 119                 case IPPROTO_DCCP:
 120                         if (xprth + 4 < skb->data ||
 121                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
 122                                 __be16 *ports = (__be16 *)xprth;
 123
 124                                 fl4->fl4_sport = ports[!!reverse];
 125                                 fl4->fl4_dport = ports[!reverse];
 126                         }
 127                         break;
 128
 129                 case IPPROTO_ICMP:
 130                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 131                                 u8 *icmp = xprth;
 132
 133                                 fl4->fl4_icmp_type = icmp[0];
 134                                 fl4->fl4_icmp_code = icmp[1];
 135                         }
 136                         break;
 137
 138                 case IPPROTO_ESP:
 139                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 140                                 __be32 *ehdr = (__be32 *)xprth;
 141
 142                                 fl4->fl4_ipsec_spi = ehdr[0];
 143                         }
 144                         break;
 145
 146                 case IPPROTO_AH:
 147                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 148                                 __be32 *ah_hdr = (__be32 *)xprth;
 149
 150                                 fl4->fl4_ipsec_spi = ah_hdr[1];
 151                         }
 152                         break;
 153
 154                 case IPPROTO_COMP:
 155                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 156                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
 157
 158                                 fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 159                         }
 160                         break;
 161
 162                 case IPPROTO_GRE:
 163                         if (pskb_may_pull(skb, xprth + 12 - skb->data)) {
 164                                 __be16 *greflags = (__be16 *)xprth;
 165                                 __be32 *gre_hdr = (__be32 *)xprth;
 166
 167                                 if (greflags[0] & GRE_KEY) {
 168                                         if (greflags[0] & GRE_CSUM)
 169                                                 gre_hdr++;
 170                                         fl4->fl4_gre_key = gre_hdr[1];
 171                                 }
 172                         }
 173                         break;
 174
 175                 default:
 176                         fl4->fl4_ipsec_spi = 0;
 177                         break;
 178                 }
 179         }
 180         fl4->flowi4_proto = iph->protocol;
 181         fl4->daddr = reverse ? iph->saddr : iph->daddr;
 182         fl4->saddr = reverse ? iph->daddr : iph->saddr;
 183         fl4->flowi4_tos = iph->tos;
 184 }
 185
 186 static inline int xfrm4_garbage_collect(struct dst_ops *ops)
 187 {
 188         struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
 189
 190         xfrm4_policy_afinfo.garbage_collect(net);
 191         return (dst_entries_get_slow(ops) > ops->gc_thresh * 2);
 192 }
 193
 194 static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk,
 195                               struct sk_buff *skb, 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, sk, skb, mtu);
 201 }
 202
 203 static void xfrm4_redirect(struct dst_entry *dst, struct sock *sk,
 204                            struct sk_buff *skb)
 205 {
 206         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 207         struct dst_entry *path = xdst->route;
 208
 209         path->ops->redirect(path, sk, skb);
 210 }
 211
 212 static void xfrm4_dst_destroy(struct dst_entry *dst)
 213 {
 214         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 215
 216         dst_destroy_metrics_generic(dst);
 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         .redirect =             xfrm4_redirect,
 236         .cow_metrics =          dst_cow_metrics_generic,
 237         .destroy =              xfrm4_dst_destroy,
 238         .ifdown =               xfrm4_dst_ifdown,
 239         .local_out =            __ip_local_out,
 240         .gc_thresh =            1024,
 241 };
 242
 243 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 244         .family =               AF_INET,
 245         .dst_ops =              &xfrm4_dst_ops,
 246         .dst_lookup =           xfrm4_dst_lookup,
 247         .get_saddr =            xfrm4_get_saddr,
 248         .decode_session =       _decode_session4,
 249         .get_tos =              xfrm4_get_tos,
 250         .init_path =            xfrm4_init_path,
 251         .fill_dst =             xfrm4_fill_dst,
 252         .blackhole_route =      ipv4_blackhole_route,
 253 };
 254
 255 #ifdef CONFIG_SYSCTL
 256 static struct ctl_table xfrm4_policy_table[] = {
 257         {
 258                 .procname       = "xfrm4_gc_thresh",
 259                 .data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
 260                 .maxlen         = sizeof(int),
 261                 .mode           = 0644,
 262                 .proc_handler   = proc_dointvec,
 263         },
 264         { }
 265 };
 266
 267 static struct ctl_table_header *sysctl_hdr;
 268 #endif
 269
 270 static void __init xfrm4_policy_init(void)
 271 {
 272         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 273 }
 274
 275 static void __exit xfrm4_policy_fini(void)
 276 {
 277 #ifdef CONFIG_SYSCTL
 278         if (sysctl_hdr)
 279                 unregister_net_sysctl_table(sysctl_hdr);
 280 #endif
 281         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 282 }
 283
 284 void __init xfrm4_init(int rt_max_size)
 285 {
 286         /*
 287          * Select a default value for the gc_thresh based on the main route
 288          * table hash size.  It seems to me the worst case scenario is when
 289          * we have ipsec operating in transport mode, in which we create a
 290          * dst_entry per socket.  The xfrm gc algorithm starts trying to remove
 291          * entries at gc_thresh, and prevents new allocations as 2*gc_thresh
 292          * so lets set an initial xfrm gc_thresh value at the rt_max_size/2.
 293          * That will let us store an ipsec connection per route table entry,
 294          * and start cleaning when were 1/2 full
 295          */
 296         xfrm4_dst_ops.gc_thresh = rt_max_size/2;
 297         dst_entries_init(&xfrm4_dst_ops);
 298
 299         xfrm4_state_init();
 300         xfrm4_policy_init();
 301 #ifdef CONFIG_SYSCTL
 302         sysctl_hdr = register_net_sysctl(&init_net, "net/ipv4",
 303                                          xfrm4_policy_table);
 304 #endif
 305 }
 306