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