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, int tos,
  22                                           const xfrm_address_t *saddr,
  23                                           const xfrm_address_t *daddr)
  24 {
  25         struct flowi fl = {
  26                 .fl4_dst = daddr->a4,
  27                 .fl4_tos = tos,
  28         };
  29         struct rtable *rt;
  30
  31         if (saddr)
  32                 fl.fl4_src = saddr->a4;
  33
  34         rt = __ip_route_output_key(net, &fl);
  35         if (!IS_ERR(rt))
  36                 return &rt->dst;
  37
  38         return ERR_CAST(rt);
  39 }
  40
  41 static int xfrm4_get_saddr(struct net *net,
  42                            xfrm_address_t *saddr, xfrm_address_t *daddr)
  43 {
  44         struct dst_entry *dst;
  45         struct rtable *rt;
  46
  47         dst = xfrm4_dst_lookup(net, 0, NULL, daddr);
  48         if (IS_ERR(dst))
  49                 return -EHOSTUNREACH;
  50
  51         rt = (struct rtable *)dst;
  52         saddr->a4 = rt->rt_src;
  53         dst_release(dst);
  54         return 0;
  55 }
  56
  57 static int xfrm4_get_tos(const struct flowi *fl)
  58 {
  59         return IPTOS_RT_MASK & fl->fl4_tos; /* Strip ECN bits */
  60 }
  61
  62 static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst,
  63                            int nfheader_len)
  64 {
  65         return 0;
  66 }
  67
  68 static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
  69                           const struct flowi *fl)
  70 {
  71         struct rtable *rt = (struct rtable *)xdst->route;
  72
  73         xdst->u.rt.fl = *fl;
  74
  75         xdst->u.dst.dev = dev;
  76         dev_hold(dev);
  77
  78         xdst->u.rt.peer = rt->peer;
  79         if (rt->peer)
  80                 atomic_inc(&rt->peer->refcnt);
  81
  82         /* Sheit... I remember I did this right. Apparently,
  83          * it was magically lost, so this code needs audit */
  84         xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
  85                                               RTCF_LOCAL);
  86         xdst->u.rt.rt_type = rt->rt_type;
  87         xdst->u.rt.rt_src = rt->rt_src;
  88         xdst->u.rt.rt_dst = rt->rt_dst;
  89         xdst->u.rt.rt_gateway = rt->rt_gateway;
  90         xdst->u.rt.rt_spec_dst = rt->rt_spec_dst;
  91
  92         return 0;
  93 }
  94
  95 static void
  96 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
  97 {
  98         struct iphdr *iph = ip_hdr(skb);
  99         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
 100
 101         memset(fl, 0, sizeof(struct flowi));
 102         fl->mark = skb->mark;
 103
 104         if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
 105                 switch (iph->protocol) {
 106                 case IPPROTO_UDP:
 107                 case IPPROTO_UDPLITE:
 108                 case IPPROTO_TCP:
 109                 case IPPROTO_SCTP:
 110                 case IPPROTO_DCCP:
 111                         if (xprth + 4 < skb->data ||
 112                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
 113                                 __be16 *ports = (__be16 *)xprth;
 114
 115                                 fl->fl_ip_sport = ports[!!reverse];
 116                                 fl->fl_ip_dport = ports[!reverse];
 117                         }
 118                         break;
 119
 120                 case IPPROTO_ICMP:
 121                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 122                                 u8 *icmp = xprth;
 123
 124                                 fl->fl_icmp_type = icmp[0];
 125                                 fl->fl_icmp_code = icmp[1];
 126                         }
 127                         break;
 128
 129                 case IPPROTO_ESP:
 130                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 131                                 __be32 *ehdr = (__be32 *)xprth;
 132
 133                                 fl->fl_ipsec_spi = ehdr[0];
 134                         }
 135                         break;
 136
 137                 case IPPROTO_AH:
 138                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 139                                 __be32 *ah_hdr = (__be32*)xprth;
 140
 141                                 fl->fl_ipsec_spi = ah_hdr[1];
 142                         }
 143                         break;
 144
 145                 case IPPROTO_COMP:
 146                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 147                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
 148
 149                                 fl->fl_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 150                         }
 151                         break;
 152
 153                 case IPPROTO_GRE:
 154                         if (pskb_may_pull(skb, xprth + 12 - skb->data)) {
 155                                 __be16 *greflags = (__be16 *)xprth;
 156                                 __be32 *gre_hdr = (__be32 *)xprth;
 157
 158                                 if (greflags[0] & GRE_KEY) {
 159                                         if (greflags[0] & GRE_CSUM)
 160                                                 gre_hdr++;
 161                                         fl->fl_gre_key = gre_hdr[1];
 162                                 }
 163                         }
 164                         break;
 165
 166                 default:
 167                         fl->fl_ipsec_spi = 0;
 168                         break;
 169                 }
 170         }
 171         fl->proto = iph->protocol;
 172         fl->fl4_dst = reverse ? iph->saddr : iph->daddr;
 173         fl->fl4_src = reverse ? iph->daddr : iph->saddr;
 174         fl->fl4_tos = iph->tos;
 175 }
 176
 177 static inline int xfrm4_garbage_collect(struct dst_ops *ops)
 178 {
 179         struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
 180
 181         xfrm4_policy_afinfo.garbage_collect(net);
 182         return (dst_entries_get_slow(ops) > ops->gc_thresh * 2);
 183 }
 184
 185 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
 186 {
 187         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 188         struct dst_entry *path = xdst->route;
 189
 190         path->ops->update_pmtu(path, mtu);
 191 }
 192
 193 static void xfrm4_dst_destroy(struct dst_entry *dst)
 194 {
 195         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 196
 197         dst_destroy_metrics_generic(dst);
 198
 199         if (likely(xdst->u.rt.peer))
 200                 inet_putpeer(xdst->u.rt.peer);
 201
 202         xfrm_dst_destroy(xdst);
 203 }
 204
 205 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 206                              int unregister)
 207 {
 208         if (!unregister)
 209                 return;
 210
 211         xfrm_dst_ifdown(dst, dev);
 212 }
 213
 214 static struct dst_ops xfrm4_dst_ops = {
 215         .family =               AF_INET,
 216         .protocol =             cpu_to_be16(ETH_P_IP),
 217         .gc =                   xfrm4_garbage_collect,
 218         .update_pmtu =          xfrm4_update_pmtu,
 219         .cow_metrics =          dst_cow_metrics_generic,
 220         .destroy =              xfrm4_dst_destroy,
 221         .ifdown =               xfrm4_dst_ifdown,
 222         .local_out =            __ip_local_out,
 223         .gc_thresh =            1024,
 224 };
 225
 226 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 227         .family =               AF_INET,
 228         .dst_ops =              &xfrm4_dst_ops,
 229         .dst_lookup =           xfrm4_dst_lookup,
 230         .get_saddr =            xfrm4_get_saddr,
 231         .decode_session =       _decode_session4,
 232         .get_tos =              xfrm4_get_tos,
 233         .init_path =            xfrm4_init_path,
 234         .fill_dst =             xfrm4_fill_dst,
 235         .blackhole_route =      ipv4_blackhole_route,
 236 };
 237
 238 #ifdef CONFIG_SYSCTL
 239 static struct ctl_table xfrm4_policy_table[] = {
 240         {
 241                 .procname       = "xfrm4_gc_thresh",
 242                 .data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
 243                 .maxlen         = sizeof(int),
 244                 .mode           = 0644,
 245                 .proc_handler   = proc_dointvec,
 246         },
 247         { }
 248 };
 249
 250 static struct ctl_table_header *sysctl_hdr;
 251 #endif
 252
 253 static void __init xfrm4_policy_init(void)
 254 {
 255         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 256 }
 257
 258 static void __exit xfrm4_policy_fini(void)
 259 {
 260 #ifdef CONFIG_SYSCTL
 261         if (sysctl_hdr)
 262                 unregister_net_sysctl_table(sysctl_hdr);
 263 #endif
 264         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 265 }
 266
 267 void __init xfrm4_init(int rt_max_size)
 268 {
 269         /*
 270          * Select a default value for the gc_thresh based on the main route
 271          * table hash size.  It seems to me the worst case scenario is when
 272          * we have ipsec operating in transport mode, in which we create a
 273          * dst_entry per socket.  The xfrm gc algorithm starts trying to remove
 274          * entries at gc_thresh, and prevents new allocations as 2*gc_thresh
 275          * so lets set an initial xfrm gc_thresh value at the rt_max_size/2.
 276          * That will let us store an ipsec connection per route table entry,
 277          * and start cleaning when were 1/2 full
 278          */
 279         xfrm4_dst_ops.gc_thresh = rt_max_size/2;
 280         dst_entries_init(&xfrm4_dst_ops);
 281
 282         xfrm4_state_init();
 283         xfrm4_policy_init();
 284 #ifdef CONFIG_SYSCTL
 285         sysctl_hdr = register_net_sysctl_table(&init_net, net_ipv4_ctl_path,
 286                                                 xfrm4_policy_table);
 287 #endif
 288 }
 289