linux/net/ipv4/xfrm4_policy.c
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   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
  19static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
  20
  21static 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
  41static 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
  50static 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
  65static int xfrm4_get_tos(const struct flowi *fl)
  66{
  67        return IPTOS_RT_MASK & fl->u.ip4.flowi4_tos; /* Strip ECN bits */
  68}
  69
  70static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst,
  71                           int nfheader_len)
  72{
  73        return 0;
  74}
  75
  76static 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
 100static 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
 183static 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
 191static 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
 200static 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
 209static 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
 218static 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
 227static 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
 240static 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
 253static 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
 264static struct ctl_table_header *sysctl_hdr;
 265#endif
 266
 267static void __init xfrm4_policy_init(void)
 268{
 269        xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 270}
 271
 272static 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
 281void __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
 304
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