xfrm6_policy.c

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/*
 * xfrm6_policy.c: based on xfrm4_policy.c
 *
 * Authors:
 *  Mitsuru KANDA @USAGI
 *  Kazunori MIYAZAWA @USAGI
 *  Kunihiro Ishiguro <[email protected]>
 *      IPv6 support
 *  YOSHIFUJI Hideaki
 *      Split up af-specific portion
 *
 */

#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <net/addrconf.h>
#include <net/dst.h>
#include <net/xfrm.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/ip6_route.h>
#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
#include <net/mip6.h>
#endif

static struct xfrm_policy_afinfo xfrm6_policy_afinfo;

static struct dst_entry *xfrm6_dst_lookup(struct net *net, int tos,
                      const xfrm_address_t *saddr,
                      const xfrm_address_t *daddr)
{
    struct flowi6 fl6;
    struct dst_entry *dst;
    int err;

    memset(&fl6, 0, sizeof(fl6));
    memcpy(&fl6.daddr, daddr, sizeof(fl6.daddr));
    if (saddr)
        memcpy(&fl6.saddr, saddr, sizeof(fl6.saddr));

    dst = ip6_route_output(net, NULL, &fl6);

    err = dst->error;
    if (dst->error) {
        dst_release(dst);
        dst = ERR_PTR(err);
    }

    return dst;
}

static int xfrm6_get_saddr(struct net *net,
               xfrm_address_t *saddr, xfrm_address_t *daddr)
{
    struct dst_entry *dst;
    struct net_device *dev;

    dst = xfrm6_dst_lookup(net, 0, NULL, daddr);
    if (IS_ERR(dst))
        return -EHOSTUNREACH;

    dev = ip6_dst_idev(dst)->dev;
    ipv6_dev_get_saddr(dev_net(dev), dev,
               (struct in6_addr *)&daddr->a6, 0,
               (struct in6_addr *)&saddr->a6);
    dst_release(dst);
    return 0;
}

static int xfrm6_get_tos(const struct flowi *fl)
{
    return 0;
}

static void xfrm6_init_dst(struct net *net, struct xfrm_dst *xdst)
{
    struct rt6_info *rt = (struct rt6_info *)xdst;

    rt6_init_peer(rt, net->ipv6.peers);
}

static int xfrm6_init_path(struct xfrm_dst *path, struct dst_entry *dst,
               int nfheader_len)
{
    if (dst->ops->family == AF_INET6) {
        struct rt6_info *rt = (struct rt6_info*)dst;
        if (rt->rt6i_node)
            path->path_cookie = rt->rt6i_node->fn_sernum;
    }

    path->u.rt6.rt6i_nfheader_len = nfheader_len;

    return 0;
}

static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
              const struct flowi *fl)
{
    struct rt6_info *rt = (struct rt6_info*)xdst->route;

    xdst->u.dst.dev = dev;
    dev_hold(dev);

    xdst->u.rt6.rt6i_idev = in6_dev_get(dev);
    if (!xdst->u.rt6.rt6i_idev)
        return -ENODEV;

    rt6_transfer_peer(&xdst->u.rt6, rt);

    /* Sheit... I remember I did this right. Apparently,
     * it was magically lost, so this code needs audit */
    xdst->u.rt6.n = neigh_clone(rt->n);
    xdst->u.rt6.rt6i_flags = rt->rt6i_flags & (RTF_ANYCAST |
                           RTF_LOCAL);
    xdst->u.rt6.rt6i_metric = rt->rt6i_metric;
    xdst->u.rt6.rt6i_node = rt->rt6i_node;
    if (rt->rt6i_node)
        xdst->route_cookie = rt->rt6i_node->fn_sernum;
    xdst->u.rt6.rt6i_gateway = rt->rt6i_gateway;
    xdst->u.rt6.rt6i_dst = rt->rt6i_dst;
    xdst->u.rt6.rt6i_src = rt->rt6i_src;

    return 0;
}

static inline void
_decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse)
{
    struct flowi6 *fl6 = &fl->u.ip6;
    int onlyproto = 0;
    u16 offset = skb_network_header_len(skb);
    const struct ipv6hdr *hdr = ipv6_hdr(skb);
    struct ipv6_opt_hdr *exthdr;
    const unsigned char *nh = skb_network_header(skb);
    u8 nexthdr = nh[IP6CB(skb)->nhoff];

    memset(fl6, 0, sizeof(struct flowi6));
    fl6->flowi6_mark = skb->mark;

    fl6->daddr = reverse ? hdr->saddr : hdr->daddr;
    fl6->saddr = reverse ? hdr->daddr : hdr->saddr;

    while (nh + offset + 1 < skb->data ||
           pskb_may_pull(skb, nh + offset + 1 - skb->data)) {
        nh = skb_network_header(skb);
        exthdr = (struct ipv6_opt_hdr *)(nh + offset);

        switch (nexthdr) {
        case NEXTHDR_FRAGMENT:
            onlyproto = 1;
        case NEXTHDR_ROUTING:
        case NEXTHDR_HOP:
        case NEXTHDR_DEST:
            offset += ipv6_optlen(exthdr);
            nexthdr = exthdr->nexthdr;
            exthdr = (struct ipv6_opt_hdr *)(nh + offset);
            break;

        case IPPROTO_UDP:
        case IPPROTO_UDPLITE:
        case IPPROTO_TCP:
        case IPPROTO_SCTP:
        case IPPROTO_DCCP:
            if (!onlyproto && (nh + offset + 4 < skb->data ||
                 pskb_may_pull(skb, nh + offset + 4 - skb->data))) {
                __be16 *ports = (__be16 *)exthdr;

                fl6->fl6_sport = ports[!!reverse];
                fl6->fl6_dport = ports[!reverse];
            }
            fl6->flowi6_proto = nexthdr;
            return;

        case IPPROTO_ICMPV6:
            if (!onlyproto && pskb_may_pull(skb, nh + offset + 2 - skb->data)) {
                u8 *icmp = (u8 *)exthdr;

                fl6->fl6_icmp_type = icmp[0];
                fl6->fl6_icmp_code = icmp[1];
            }
            fl6->flowi6_proto = nexthdr;
            return;

#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
        case IPPROTO_MH:
            if (!onlyproto && pskb_may_pull(skb, nh + offset + 3 - skb->data)) {
                struct ip6_mh *mh;
                mh = (struct ip6_mh *)exthdr;

                fl6->fl6_mh_type = mh->ip6mh_type;
            }
            fl6->flowi6_proto = nexthdr;
            return;
#endif

        /* XXX Why are there these headers? */
        case IPPROTO_AH:
        case IPPROTO_ESP:
        case IPPROTO_COMP:
        default:
            fl6->fl6_ipsec_spi = 0;
            fl6->flowi6_proto = nexthdr;
            return;
        }
    }
}

static inline int xfrm6_garbage_collect(struct dst_ops *ops)
{
    struct net *net = container_of(ops, struct net, xfrm.xfrm6_dst_ops);

    xfrm6_policy_afinfo.garbage_collect(net);
    return dst_entries_get_fast(ops) > ops->gc_thresh * 2;
}

static void xfrm6_update_pmtu(struct dst_entry *dst, struct sock *sk,
                  struct sk_buff *skb, u32 mtu)
{
    struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
    struct dst_entry *path = xdst->route;

    path->ops->update_pmtu(path, sk, skb, mtu);
}

static void xfrm6_redirect(struct dst_entry *dst, struct sock *sk,
               struct sk_buff *skb)
{
    struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
    struct dst_entry *path = xdst->route;

    path->ops->redirect(path, sk, skb);
}

static void xfrm6_dst_destroy(struct dst_entry *dst)
{
    struct xfrm_dst *xdst = (struct xfrm_dst *)dst;

    if (likely(xdst->u.rt6.rt6i_idev))
        in6_dev_put(xdst->u.rt6.rt6i_idev);
    dst_destroy_metrics_generic(dst);
    if (rt6_has_peer(&xdst->u.rt6)) {
        struct inet_peer *peer = rt6_peer_ptr(&xdst->u.rt6);
        inet_putpeer(peer);
    }
    xfrm_dst_destroy(xdst);
}

static void xfrm6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
                 int unregister)
{
    struct xfrm_dst *xdst;

    if (!unregister)
        return;

    xdst = (struct xfrm_dst *)dst;
    if (xdst->u.rt6.rt6i_idev->dev == dev) {
        struct inet6_dev *loopback_idev =
            in6_dev_get(dev_net(dev)->loopback_dev);
        BUG_ON(!loopback_idev);

        do {
            in6_dev_put(xdst->u.rt6.rt6i_idev);
            xdst->u.rt6.rt6i_idev = loopback_idev;
            in6_dev_hold(loopback_idev);
            xdst = (struct xfrm_dst *)xdst->u.dst.child;
        } while (xdst->u.dst.xfrm);

        __in6_dev_put(loopback_idev);
    }

    xfrm_dst_ifdown(dst, dev);
}

static struct dst_ops xfrm6_dst_ops = {
    .family =       AF_INET6,
    .protocol =     cpu_to_be16(ETH_P_IPV6),
    .gc =           xfrm6_garbage_collect,
    .update_pmtu =      xfrm6_update_pmtu,
    .redirect =     xfrm6_redirect,
    .cow_metrics =      dst_cow_metrics_generic,
    .destroy =      xfrm6_dst_destroy,
    .ifdown =       xfrm6_dst_ifdown,
    .local_out =        __ip6_local_out,
    .gc_thresh =        1024,
};

static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
    .family =       AF_INET6,
    .dst_ops =      &xfrm6_dst_ops,
    .dst_lookup =       xfrm6_dst_lookup,
    .get_saddr =        xfrm6_get_saddr,
    .decode_session =   _decode_session6,
    .get_tos =      xfrm6_get_tos,
    .init_dst =     xfrm6_init_dst,
    .init_path =        xfrm6_init_path,
    .fill_dst =     xfrm6_fill_dst,
    .blackhole_route =  ip6_blackhole_route,
};

static int __init xfrm6_policy_init(void)
{
    return xfrm_policy_register_afinfo(&xfrm6_policy_afinfo);
}

static void xfrm6_policy_fini(void)
{
    xfrm_policy_unregister_afinfo(&xfrm6_policy_afinfo);
}

#ifdef CONFIG_SYSCTL
static struct ctl_table xfrm6_policy_table[] = {
    {
        .procname       = "xfrm6_gc_thresh",
        .data       = &init_net.xfrm.xfrm6_dst_ops.gc_thresh,
        .maxlen     = sizeof(int),
        .mode       = 0644,
        .proc_handler   = proc_dointvec,
    },
    { }
};

static struct ctl_table_header *sysctl_hdr;
#endif

int __init xfrm6_init(void)
{
    int ret;
    unsigned int gc_thresh;

    /*
     * We need a good default value for the xfrm6 gc threshold.
     * In ipv4 we set it to the route hash table size * 8, which
     * is half the size of the maximaum route cache for ipv4.  It
     * would be good to do the same thing for v6, except the table is
     * constructed differently here.  Here each table for a net namespace
     * can have FIB_TABLE_HASHSZ entries, so lets go with the same
     * computation that we used for ipv4 here.  Also, lets keep the initial
     * gc_thresh to a minimum of 1024, since, the ipv6 route cache defaults
     * to that as a minimum as well
     */
    gc_thresh = FIB6_TABLE_HASHSZ * 8;
    xfrm6_dst_ops.gc_thresh = (gc_thresh < 1024) ? 1024 : gc_thresh;
    dst_entries_init(&xfrm6_dst_ops);

    ret = xfrm6_policy_init();
    if (ret) {
        dst_entries_destroy(&xfrm6_dst_ops);
        goto out;
    }
    ret = xfrm6_state_init();
    if (ret)
        goto out_policy;

#ifdef CONFIG_SYSCTL
    sysctl_hdr = register_net_sysctl(&init_net, "net/ipv6",
                     xfrm6_policy_table);
#endif
out:
    return ret;
out_policy:
    xfrm6_policy_fini();
    goto out;
}

void xfrm6_fini(void)
{
#ifdef CONFIG_SYSCTL
    if (sysctl_hdr)
        unregister_net_sysctl_table(sysctl_hdr);
#endif
    //xfrm6_input_fini();
    xfrm6_policy_fini();
    xfrm6_state_fini();
    dst_entries_destroy(&xfrm6_dst_ops);
}