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 <net/dst.h>
  15 #include <net/xfrm.h>
  16 #include <net/ip.h>
  17
  18 static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
  19
  20 static struct dst_entry *xfrm4_dst_lookup(struct net *net, int tos,
  21                                           xfrm_address_t *saddr,
  22                                           xfrm_address_t *daddr)
  23 {
  24         struct flowi fl = {
  25                 .nl_u = {
  26                         .ip4_u = {
  27                                 .tos = tos,
  28                                 .daddr = daddr->a4,
  29                         },
  30                 },
  31         };
  32         struct dst_entry *dst;
  33         struct rtable *rt;
  34         int err;
  35
  36         if (saddr)
  37                 fl.fl4_src = saddr->a4;
  38
  39         err = __ip_route_output_key(net, &rt, &fl);
  40         dst = &rt->dst;
  41         if (err)
  42                 dst = ERR_PTR(err);
  43         return dst;
  44 }
  45
  46 static int xfrm4_get_saddr(struct net *net,
  47                            xfrm_address_t *saddr, xfrm_address_t *daddr)
  48 {
  49         struct dst_entry *dst;
  50         struct rtable *rt;
  51
  52         dst = xfrm4_dst_lookup(net, 0, NULL, daddr);
  53         if (IS_ERR(dst))
  54                 return -EHOSTUNREACH;
  55
  56         rt = (struct rtable *)dst;
  57         saddr->a4 = rt->rt_src;
  58         dst_release(dst);
  59         return 0;
  60 }
  61
  62 static int xfrm4_get_tos(struct flowi *fl)
  63 {
  64         return IPTOS_RT_MASK & fl->fl4_tos; /* Strip ECN bits */
  65 }
  66
  67 static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst,
  68                            int nfheader_len)
  69 {
  70         return 0;
  71 }
  72
  73 static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
  74                           struct flowi *fl)
  75 {
  76         struct rtable *rt = (struct rtable *)xdst->route;
  77
  78         xdst->u.rt.fl = *fl;
  79
  80         xdst->u.dst.dev = dev;
  81         dev_hold(dev);
  82
  83         xdst->u.rt.peer = rt->peer;
  84         if (rt->peer)
  85                 atomic_inc(&rt->peer->refcnt);
  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_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
  90                                               RTCF_LOCAL);
  91         xdst->u.rt.rt_type = rt->rt_type;
  92         xdst->u.rt.rt_src = rt->rt_src;
  93         xdst->u.rt.rt_dst = rt->rt_dst;
  94         xdst->u.rt.rt_gateway = rt->rt_gateway;
  95         xdst->u.rt.rt_spec_dst = rt->rt_spec_dst;
  96
  97         return 0;
  98 }
  99
 100 static void
 101 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
 102 {
 103         struct iphdr *iph = ip_hdr(skb);
 104         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
 105
 106         memset(fl, 0, sizeof(struct flowi));
 107         fl->mark = skb->mark;
 108
 109         if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
 110                 switch (iph->protocol) {
 111                 case IPPROTO_UDP:
 112                 case IPPROTO_UDPLITE:
 113                 case IPPROTO_TCP:
 114                 case IPPROTO_SCTP:
 115                 case IPPROTO_DCCP:
 116                         if (xprth + 4 < skb->data ||
 117                             pskb_may_pull(skb, xprth + 4 - skb->data)) {
 118                                 __be16 *ports = (__be16 *)xprth;
 119
 120                                 fl->fl_ip_sport = ports[!!reverse];
 121                                 fl->fl_ip_dport = ports[!reverse];
 122                         }
 123                         break;
 124
 125                 case IPPROTO_ICMP:
 126                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 127                                 u8 *icmp = xprth;
 128
 129                                 fl->fl_icmp_type = icmp[0];
 130                                 fl->fl_icmp_code = icmp[1];
 131                         }
 132                         break;
 133
 134                 case IPPROTO_ESP:
 135                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 136                                 __be32 *ehdr = (__be32 *)xprth;
 137
 138                                 fl->fl_ipsec_spi = ehdr[0];
 139                         }
 140                         break;
 141
 142                 case IPPROTO_AH:
 143                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 144                                 __be32 *ah_hdr = (__be32*)xprth;
 145
 146                                 fl->fl_ipsec_spi = ah_hdr[1];
 147                         }
 148                         break;
 149
 150                 case IPPROTO_COMP:
 151                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 152                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
 153
 154                                 fl->fl_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 155                         }
 156                         break;
 157                 default:
 158                         fl->fl_ipsec_spi = 0;
 159                         break;
 160                 }
 161         }
 162         fl->proto = iph->protocol;
 163         fl->fl4_dst = reverse ? iph->saddr : iph->daddr;
 164         fl->fl4_src = reverse ? iph->daddr : iph->saddr;
 165         fl->fl4_tos = iph->tos;
 166 }
 167
 168 static inline int xfrm4_garbage_collect(struct dst_ops *ops)
 169 {
 170         struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
 171
 172         xfrm4_policy_afinfo.garbage_collect(net);
 173         return (dst_entries_get_slow(ops) > ops->gc_thresh * 2);
 174 }
 175
 176 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
 177 {
 178         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 179         struct dst_entry *path = xdst->route;
 180
 181         path->ops->update_pmtu(path, mtu);
 182 }
 183
 184 static void xfrm4_dst_destroy(struct dst_entry *dst)
 185 {
 186         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 187
 188         if (likely(xdst->u.rt.peer))
 189                 inet_putpeer(xdst->u.rt.peer);
 190         xfrm_dst_destroy(xdst);
 191 }
 192
 193 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 194                              int unregister)
 195 {
 196         if (!unregister)
 197                 return;
 198
 199         xfrm_dst_ifdown(dst, dev);
 200 }
 201
 202 static struct dst_ops xfrm4_dst_ops = {
 203         .family =               AF_INET,
 204         .protocol =             cpu_to_be16(ETH_P_IP),
 205         .gc =                   xfrm4_garbage_collect,
 206         .update_pmtu =          xfrm4_update_pmtu,
 207         .destroy =              xfrm4_dst_destroy,
 208         .ifdown =               xfrm4_dst_ifdown,
 209         .local_out =            __ip_local_out,
 210         .gc_thresh =            1024,
 211 };
 212
 213 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 214         .family =               AF_INET,
 215         .dst_ops =              &xfrm4_dst_ops,
 216         .dst_lookup =           xfrm4_dst_lookup,
 217         .get_saddr =            xfrm4_get_saddr,
 218         .decode_session =       _decode_session4,
 219         .get_tos =              xfrm4_get_tos,
 220         .init_path =            xfrm4_init_path,
 221         .fill_dst =             xfrm4_fill_dst,
 222 };
 223
 224 #ifdef CONFIG_SYSCTL
 225 static struct ctl_table xfrm4_policy_table[] = {
 226         {
 227                 .procname       = "xfrm4_gc_thresh",
 228                 .data           = &init_net.xfrm.xfrm4_dst_ops.gc_thresh,
 229                 .maxlen         = sizeof(int),
 230                 .mode           = 0644,
 231                 .proc_handler   = proc_dointvec,
 232         },
 233         { }
 234 };
 235
 236 static struct ctl_table_header *sysctl_hdr;
 237 #endif
 238
 239 static void __init xfrm4_policy_init(void)
 240 {
 241         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 242 }
 243
 244 static void __exit xfrm4_policy_fini(void)
 245 {
 246 #ifdef CONFIG_SYSCTL
 247         if (sysctl_hdr)
 248                 unregister_net_sysctl_table(sysctl_hdr);
 249 #endif
 250         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 251 }
 252
 253 void __init xfrm4_init(int rt_max_size)
 254 {
 255         /*
 256          * Select a default value for the gc_thresh based on the main route
 257          * table hash size.  It seems to me the worst case scenario is when
 258          * we have ipsec operating in transport mode, in which we create a
 259          * dst_entry per socket.  The xfrm gc algorithm starts trying to remove
 260          * entries at gc_thresh, and prevents new allocations as 2*gc_thresh
 261          * so lets set an initial xfrm gc_thresh value at the rt_max_size/2.
 262          * That will let us store an ipsec connection per route table entry,
 263          * and start cleaning when were 1/2 full
 264          */
 265         xfrm4_dst_ops.gc_thresh = rt_max_size/2;
 266         dst_entries_init(&xfrm4_dst_ops);
 267
 268         xfrm4_state_init();
 269         xfrm4_policy_init();
 270 #ifdef CONFIG_SYSCTL
 271         sysctl_hdr = register_net_sysctl_table(&init_net, net_ipv4_ctl_path,
 272                                                 xfrm4_policy_table);
 273 #endif
 274 }
 275