xfrm_policy.c

/* 
 * xfrm_policy.c
 *
 * Changes:
 *	Mitsuru KANDA @USAGI
 * 	Kazunori MIYAZAWA @USAGI
 * 	Kunihiro Ishiguro <kunihiro@ipinfusion.com>
 * 		IPv6 support
 * 	Kazunori MIYAZAWA @USAGI
 * 	YOSHIFUJI Hideaki
 * 		Split up af-specific portion
 *	Derek Atkins <derek@ihtfp.com>		Add the post_input processor
 *
 */

#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/notifier.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/module.h>
#include <linux/cache.h>
#include <net/xfrm.h>
#include <net/ip.h>

#include "xfrm_hash.h"

DEFINE_MUTEX(xfrm_cfg_mutex);
EXPORT_SYMBOL(xfrm_cfg_mutex);

static DEFINE_RWLOCK(xfrm_policy_lock);

unsigned int xfrm_policy_count[XFRM_POLICY_MAX*2];
EXPORT_SYMBOL(xfrm_policy_count);

static DEFINE_RWLOCK(xfrm_policy_afinfo_lock);
static struct xfrm_policy_afinfo *xfrm_policy_afinfo[NPROTO];

static kmem_cache_t *xfrm_dst_cache __read_mostly;

static struct work_struct xfrm_policy_gc_work;
static HLIST_HEAD(xfrm_policy_gc_list);
static DEFINE_SPINLOCK(xfrm_policy_gc_lock);

static struct xfrm_policy_afinfo *xfrm_policy_get_afinfo(unsigned short family);
static void xfrm_policy_put_afinfo(struct xfrm_policy_afinfo *afinfo);
static struct xfrm_policy_afinfo *xfrm_policy_lock_afinfo(unsigned int family);
static void xfrm_policy_unlock_afinfo(struct xfrm_policy_afinfo *afinfo);

static inline int
__xfrm4_selector_match(struct xfrm_selector *sel, struct flowi *fl)
{
	return  addr_match(&fl->fl4_dst, &sel->daddr, sel->prefixlen_d) &&
		addr_match(&fl->fl4_src, &sel->saddr, sel->prefixlen_s) &&
		!((xfrm_flowi_dport(fl) ^ sel->dport) & sel->dport_mask) &&
		!((xfrm_flowi_sport(fl) ^ sel->sport) & sel->sport_mask) &&
		(fl->proto == sel->proto || !sel->proto) &&
		(fl->oif == sel->ifindex || !sel->ifindex);
}

static inline int
__xfrm6_selector_match(struct xfrm_selector *sel, struct flowi *fl)
{
	return  addr_match(&fl->fl6_dst, &sel->daddr, sel->prefixlen_d) &&
		addr_match(&fl->fl6_src, &sel->saddr, sel->prefixlen_s) &&
		!((xfrm_flowi_dport(fl) ^ sel->dport) & sel->dport_mask) &&
		!((xfrm_flowi_sport(fl) ^ sel->sport) & sel->sport_mask) &&
		(fl->proto == sel->proto || !sel->proto) &&
		(fl->oif == sel->ifindex || !sel->ifindex);
}

int xfrm_selector_match(struct xfrm_selector *sel, struct flowi *fl,
		    unsigned short family)
{
	switch (family) {
	case AF_INET:
		return __xfrm4_selector_match(sel, fl);
	case AF_INET6:
		return __xfrm6_selector_match(sel, fl);
	}
	return 0;
}

int xfrm_register_type(struct xfrm_type *type, unsigned short family)
{
	struct xfrm_policy_afinfo *afinfo = xfrm_policy_lock_afinfo(family);
	struct xfrm_type **typemap;
	int err = 0;

	if (unlikely(afinfo == NULL))
		return -EAFNOSUPPORT;
	typemap = afinfo->type_map;

	if (likely(typemap[type->proto] == NULL))
		typemap[type->proto] = type;
	else
		err = -EEXIST;
	xfrm_policy_unlock_afinfo(afinfo);
	return err;
}
EXPORT_SYMBOL(xfrm_register_type);

int xfrm_unregister_type(struct xfrm_type *type, unsigned short family)
{
	struct xfrm_policy_afinfo *afinfo = xfrm_policy_lock_afinfo(family);
	struct xfrm_type **typemap;
	int err = 0;

	if (unlikely(afinfo == NULL))
		return -EAFNOSUPPORT;
	typemap = afinfo->type_map;

	if (unlikely(typemap[type->proto] != type))
		err = -ENOENT;
	else
		typemap[type->proto] = NULL;
	xfrm_policy_unlock_afinfo(afinfo);
	return err;
}
EXPORT_SYMBOL(xfrm_unregister_type);

struct xfrm_type *xfrm_get_type(u8 proto, unsigned short family)
{
	struct xfrm_policy_afinfo *afinfo;
	struct xfrm_type **typemap;
	struct xfrm_type *type;
	int modload_attempted = 0;

retry:
	afinfo = xfrm_policy_get_afinfo(family);
	if (unlikely(afinfo == NULL))
		return NULL;
	typemap = afinfo->type_map;

	type = typemap[proto];
	if (unlikely(type && !try_module_get(type->owner)))
		type = NULL;
	if (!type && !modload_attempted) {
		xfrm_policy_put_afinfo(afinfo);
		request_module("xfrm-type-%d-%d",
			       (int) family, (int) proto);
		modload_attempted = 1;
		goto retry;
	}

	xfrm_policy_put_afinfo(afinfo);
	return type;
}

int xfrm_dst_lookup(struct xfrm_dst **dst, struct flowi *fl, 
		    unsigned short family)
{
	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
	int err = 0;

	if (unlikely(afinfo == NULL))
		return -EAFNOSUPPORT;

	if (likely(afinfo->dst_lookup != NULL))
		err = afinfo->dst_lookup(dst, fl);
	else
		err = -EINVAL;
	xfrm_policy_put_afinfo(afinfo);
	return err;
}
EXPORT_SYMBOL(xfrm_dst_lookup);

void xfrm_put_type(struct xfrm_type *type)
{
	module_put(type->owner);
}

int xfrm_register_mode(struct xfrm_mode *mode, int family)
{
	struct xfrm_policy_afinfo *afinfo;
	struct xfrm_mode **modemap;
	int err;

	if (unlikely(mode->encap >= XFRM_MODE_MAX))
		return -EINVAL;

	afinfo = xfrm_policy_lock_afinfo(family);
	if (unlikely(afinfo == NULL))
		return -EAFNOSUPPORT;

	err = -EEXIST;
	modemap = afinfo->mode_map;
	if (likely(modemap[mode->encap] == NULL)) {
		modemap[mode->encap] = mode;
		err = 0;
	}

	xfrm_policy_unlock_afinfo(afinfo);
	return err;
}
EXPORT_SYMBOL(xfrm_register_mode);

int xfrm_unregister_mode(struct xfrm_mode *mode, int family)
{
	struct xfrm_policy_afinfo *afinfo;
	struct xfrm_mode **modemap;
	int err;

	if (unlikely(mode->encap >= XFRM_MODE_MAX))
		return -EINVAL;

	afinfo = xfrm_policy_lock_afinfo(family);
	if (unlikely(afinfo == NULL))
		return -EAFNOSUPPORT;

	err = -ENOENT;
	modemap = afinfo->mode_map;
	if (likely(modemap[mode->encap] == mode)) {
		modemap[mode->encap] = NULL;
		err = 0;
	}

	xfrm_policy_unlock_afinfo(afinfo);
	return err;
}
EXPORT_SYMBOL(xfrm_unregister_mode);

struct xfrm_mode *xfrm_get_mode(unsigned int encap, int family)
{
	struct xfrm_policy_afinfo *afinfo;
	struct xfrm_mode *mode;
	int modload_attempted = 0;

	if (unlikely(encap >= XFRM_MODE_MAX))
		return NULL;

retry:
	afinfo = xfrm_policy_get_afinfo(family);
	if (unlikely(afinfo == NULL))
		return NULL;

	mode = afinfo->mode_map[encap];
	if (unlikely(mode && !try_module_get(mode->owner)))
		mode = NULL;
	if (!mode && !modload_attempted) {
		xfrm_policy_put_afinfo(afinfo);
		request_module("xfrm-mode-%d-%d", family, encap);
		modload_attempted = 1;
		goto retry;
	}

	xfrm_policy_put_afinfo(afinfo);
	return mode;
}

void xfrm_put_mode(struct xfrm_mode *mode)
{
	module_put(mode->owner);
}

static inline unsigned long make_jiffies(long secs)
{
	if (secs >= (MAX_SCHEDULE_TIMEOUT-1)/HZ)
		return MAX_SCHEDULE_TIMEOUT-1;
	else
	        return secs*HZ;
}

static void xfrm_policy_timer(unsigned long data)
{
	struct xfrm_policy *xp = (struct xfrm_policy*)data;
	unsigned long now = (unsigned long)xtime.tv_sec;
	long next = LONG_MAX;
	int warn = 0;
	int dir;

	read_lock(&xp->lock);

	if (xp->dead)
		goto out;

	dir = xfrm_policy_id2dir(xp->index);

	if (xp->lft.hard_add_expires_seconds) {
		long tmo = xp->lft.hard_add_expires_seconds +
			xp->curlft.add_time - now;
		if (tmo <= 0)
			goto expired;
		if (tmo < next)
			next = tmo;
	}
	if (xp->lft.hard_use_expires_seconds) {
		long tmo = xp->lft.hard_use_expires_seconds +
			(xp->curlft.use_time ? : xp->curlft.add_time) - now;
		if (tmo <= 0)
			goto expired;
		if (tmo < next)
			next = tmo;
	}
	if (xp->lft.soft_add_expires_seconds) {
		long tmo = xp->lft.soft_add_expires_seconds +
			xp->curlft.add_time - now;
		if (tmo <= 0) {
			warn = 1;
			tmo = XFRM_KM_TIMEOUT;
		}
		if (tmo < next)
			next = tmo;
	}
	if (xp->lft.soft_use_expires_seconds) {
		long tmo = xp->lft.soft_use_expires_seconds +
			(xp->curlft.use_time ? : xp->curlft.add_time) - now;
		if (tmo <= 0) {
			warn = 1;
			tmo = XFRM_KM_TIMEOUT;
		}
		if (tmo < next)
			next = tmo;
	}

	if (warn)
		km_policy_expired(xp, dir, 0, 0);
	if (next != LONG_MAX &&
	    !mod_timer(&xp->timer, jiffies + make_jiffies(next)))
		xfrm_pol_hold(xp);

out:
	read_unlock(&xp->lock);
	xfrm_pol_put(xp);
	return;

expired:
	read_unlock(&xp->lock);
	if (!xfrm_policy_delete(xp, dir))
		km_policy_expired(xp, dir, 1, 0);
	xfrm_pol_put(xp);
}


/* Allocate xfrm_policy. Not used here, it is supposed to be used by pfkeyv2
 * SPD calls.
 */

struct xfrm_policy *xfrm_policy_alloc(gfp_t gfp)
{
	struct xfrm_policy *policy;

	policy = kzalloc(sizeof(struct xfrm_policy), gfp);

	if (policy) {
		INIT_HLIST_NODE(&policy->bydst);
		INIT_HLIST_NODE(&policy->byidx);
		rwlock_init(&policy->lock);
		atomic_set(&policy->refcnt, 1);
		init_timer(&policy->timer);
		policy->timer.data = (unsigned long)policy;
		policy->timer.function = xfrm_policy_timer;
	}
	return policy;
}
EXPORT_SYMBOL(xfrm_policy_alloc);

/* Destroy xfrm_policy: descendant resources must be released to this moment. */

void __xfrm_policy_destroy(struct xfrm_policy *policy)
{
	BUG_ON(!policy->dead);

	BUG_ON(policy->bundles);

	if (del_timer(&policy->timer))
		BUG();

	security_xfrm_policy_free(policy);
	kfree(policy);
}
EXPORT_SYMBOL(__xfrm_policy_destroy);

static void xfrm_policy_gc_kill(struct xfrm_policy *policy)
{
	struct dst_entry *dst;

	while ((dst = policy->bundles) != NULL) {
		policy->bundles = dst->next;
		dst_free(dst);
	}

	if (del_timer(&policy->timer))
		atomic_dec(&policy->refcnt);

	if (atomic_read(&policy->refcnt) > 1)
		flow_cache_flush();

	xfrm_pol_put(policy);
}

static void xfrm_policy_gc_task(struct work_struct *work)
{
	struct xfrm_policy *policy;
	struct hlist_node *entry, *tmp;
	struct hlist_head gc_list;

	spin_lock_bh(&xfrm_policy_gc_lock);
	gc_list.first = xfrm_policy_gc_list.first;
	INIT_HLIST_HEAD(&xfrm_policy_gc_list);
	spin_unlock_bh(&xfrm_policy_gc_lock);

	hlist_for_each_entry_safe(policy, entry, tmp, &gc_list, bydst)
		xfrm_policy_gc_kill(policy);
}

/* Rule must be locked. Release descentant resources, announce
 * entry dead. The rule must be unlinked from lists to the moment.
 */

static void xfrm_policy_kill(struct xfrm_policy *policy)
{
	int dead;

	write_lock_bh(&policy->lock);
	dead = policy->dead;
	policy->dead = 1;
	write_unlock_bh(&policy->lock);

	if (unlikely(dead)) {
		WARN_ON(1);
		return;
	}

	spin_lock(&xfrm_policy_gc_lock);
	hlist_add_head(&policy->bydst, &xfrm_policy_gc_list);
	spin_unlock(&xfrm_policy_gc_lock);

	schedule_work(&xfrm_policy_gc_work);
}

struct xfrm_policy_hash {
	struct hlist_head	*table;
	unsigned int		hmask;
};

static struct hlist_head xfrm_policy_inexact[XFRM_POLICY_MAX*2];
static struct xfrm_policy_hash xfrm_policy_bydst[XFRM_POLICY_MAX*2] __read_mostly;
static struct hlist_head *xfrm_policy_byidx __read_mostly;
static unsigned int xfrm_idx_hmask __read_mostly;
static unsigned int xfrm_policy_hashmax __read_mostly = 1 * 1024 * 1024;

static inline unsigned int idx_hash(u32 index)
{
	return __idx_hash(index, xfrm_idx_hmask);
}

static struct hlist_head *policy_hash_bysel(struct xfrm_selector *sel, unsigned short family, int dir)
{
	unsigned int hmask = xfrm_policy_bydst[dir].hmask;
	unsigned int hash = __sel_hash(sel, family, hmask);

	return (hash == hmask + 1 ?
		&xfrm_policy_inexact[dir] :
		xfrm_policy_bydst[dir].table + hash);
}

static struct hlist_head *policy_hash_direct(xfrm_address_t *daddr, xfrm_address_t *saddr, unsigned short family, int dir)
{
	unsigned int hmask = xfrm_policy_bydst[dir].hmask;
	unsigned int hash = __addr_hash(daddr, saddr, family, hmask);

	return xfrm_policy_bydst[dir].table + hash;
}

static void xfrm_dst_hash_transfer(struct hlist_head *list,
				   struct hlist_head *ndsttable,
				   unsigned int nhashmask)
{
	struct hlist_node *entry, *tmp;
	struct xfrm_policy *pol;

	hlist_for_each_entry_safe(pol, entry, tmp, list, bydst) {
		unsigned int h;

		h = __addr_hash(&pol->selector.daddr, &pol->selector.saddr,
				pol->family, nhashmask);
		hlist_add_head(&pol->bydst, ndsttable+h);
	}
}

static void xfrm_idx_hash_transfer(struct hlist_head *list,
				   struct hlist_head *nidxtable,
				   unsigned int nhashmask)
{
	struct hlist_node *entry, *tmp;
	struct xfrm_policy *pol;

	hlist_for_each_entry_safe(pol, entry, tmp, list, byidx) {
		unsigned int h;

		h = __idx_hash(pol->index, nhashmask);
		hlist_add_head(&pol->byidx, nidxtable+h);
	}
}

static unsigned long xfrm_new_hash_mask(unsigned int old_hmask)
{
	return ((old_hmask + 1) << 1) - 1;
}

static void xfrm_bydst_resize(int dir)
{
	unsigned int hmask = xfrm_policy_bydst[dir].hmask;
	unsigned int nhashmask = xfrm_new_hash_mask(hmask);
	unsigned int nsize = (nhashmask + 1) * sizeof(struct hlist_head);
	struct hlist_head *odst = xfrm_policy_bydst[dir].table;
	struct hlist_head *ndst = xfrm_hash_alloc(nsize);
	int i;

	if (!ndst)
		return;

	write_lock_bh(&xfrm_policy_lock);

	for (i = hmask; i >= 0; i--)
		xfrm_dst_hash_transfer(odst + i, ndst, nhashmask);

	xfrm_policy_bydst[dir].table = ndst;
	xfrm_policy_bydst[dir].hmask = nhashmask;

	write_unlock_bh(&xfrm_policy_lock);

	xfrm_hash_free(odst, (hmask + 1) * sizeof(struct hlist_head));
}

static void xfrm_byidx_resize(int total)
{
	unsigned int hmask = xfrm_idx_hmask;
	unsigned int nhashmask = xfrm_new_hash_mask(hmask);
	unsigned int nsize = (nhashmask + 1) * sizeof(struct hlist_head);
	struct hlist_head *oidx = xfrm_policy_byidx;
	struct hlist_head *nidx = xfrm_hash_alloc(nsize);
	int i;

	if (!nidx)
		return;

	write_lock_bh(&xfrm_policy_lock);

	for (i = hmask; i >= 0; i--)
		xfrm_idx_hash_transfer(oidx + i, nidx, nhashmask);

	xfrm_policy_byidx = nidx;
	xfrm_idx_hmask = nhashmask;

	write_unlock_bh(&xfrm_policy_lock);

	xfrm_hash_free(oidx, (hmask + 1) * sizeof(struct hlist_head));
}

static inline int xfrm_bydst_should_resize(int dir, int *total)
{
	unsigned int cnt = xfrm_policy_count[dir];
	unsigned int hmask = xfrm_policy_bydst[dir].hmask;

	if (total)
		*total += cnt;

	if ((hmask + 1) < xfrm_policy_hashmax &&
	    cnt > hmask)
		return 1;

	return 0;
}

static inline int xfrm_byidx_should_resize(int total)
{
	unsigned int hmask = xfrm_idx_hmask;

	if ((hmask + 1) < xfrm_policy_hashmax &&
	    total > hmask)
		return 1;

	return 0;
}

static DEFINE_MUTEX(hash_resize_mutex);

static void xfrm_hash_resize(struct work_struct *__unused)
{
	int dir, total;

	mutex_lock(&hash_resize_mutex);

	total = 0;
	for (dir = 0; dir < XFRM_POLICY_MAX * 2; dir++) {
		if (xfrm_bydst_should_resize(dir, &total))
			xfrm_bydst_resize(dir);
	}
	if (xfrm_byidx_should_resize(total))
		xfrm_byidx_resize(total);

	mutex_unlock(&hash_resize_mutex);
}

static DECLARE_WORK(xfrm_hash_work, xfrm_hash_resize);

/* Generate new index... KAME seems to generate them ordered by cost
 * of an absolute inpredictability of ordering of rules. This will not pass. */
static u32 xfrm_gen_index(u8 type, int dir)
{
	static u32 idx_generator;

	for (;;) {
		struct hlist_node *entry;
		struct hlist_head *list;
		struct xfrm_policy *p;
		u32 idx;
		int found;

		idx = (idx_generator | dir);
		idx_generator += 8;
		if (idx == 0)
			idx = 8;
		list = xfrm_policy_byidx + idx_hash(idx);
		found = 0;
		hlist_for_each_entry(p, entry, list, byidx) {
			if (p->index == idx) {
				found = 1;
				break;
			}
		}
		if (!found)
			return idx;
	}
}

static inline int selector_cmp(struct xfrm_selector *s1, struct xfrm_selector *s2)
{
	u32 *p1 = (u32 *) s1;
	u32 *p2 = (u32 *) s2;
	int len = sizeof(struct xfrm_selector) / sizeof(u32);
	int i;

	for (i = 0; i < len; i++) {
		if (p1[i] != p2[i])
			return 1;
	}

	return 0;
}

int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl)
{
	struct xfrm_policy *pol;
	struct xfrm_policy *delpol;
	struct hlist_head *chain;
	struct hlist_node *entry, *newpos, *last;
	struct dst_entry *gc_list;

	write_lock_bh(&xfrm_policy_lock);
	chain = policy_hash_bysel(&policy->selector, policy->family, dir);
	delpol = NULL;
	newpos = NULL;
	last = NULL;
	hlist_for_each_entry(pol, entry, chain, bydst) {
		if (!delpol &&
		    pol->type == policy->type &&
		    !selector_cmp(&pol->selector, &policy->selector) &&
		    xfrm_sec_ctx_match(pol->security, policy->security)) {
			if (excl) {
				write_unlock_bh(&xfrm_policy_lock);
				return -EEXIST;
			}
			delpol = pol;
			if (policy->priority > pol->priority)
				continue;
		} else if (policy->priority >= pol->priority) {
			last = &pol->bydst;
			continue;
		}
		if (!newpos)
			newpos = &pol->bydst;
		if (delpol)
			break;
		last = &pol->bydst;
	}
	if (!newpos)
		newpos = last;
	if (newpos)
		hlist_add_after(newpos, &policy->bydst);
	else
		hlist_add_head(&policy->bydst, chain);
	xfrm_pol_hold(policy);
	xfrm_policy_count[dir]++;
	atomic_inc(&flow_cache_genid);
	if (delpol) {
		hlist_del(&delpol->bydst);
		hlist_del(&delpol->byidx);
		xfrm_policy_count[dir]--;
	}
	policy->index = delpol ? delpol->index : xfrm_gen_index(policy->type, dir);
	hlist_add_head(&policy->byidx, xfrm_policy_byidx+idx_hash(policy->index));
	policy->curlft.add_time = (unsigned long)xtime.tv_sec;
	policy->curlft.use_time = 0;
	if (!mod_timer(&policy->timer, jiffies + HZ))
		xfrm_pol_hold(policy);
	write_unlock_bh(&xfrm_policy_lock);

	if (delpol)
		xfrm_policy_kill(delpol);
	else if (xfrm_bydst_should_resize(dir, NULL))
		schedule_work(&xfrm_hash_work);

	read_lock_bh(&xfrm_policy_lock);
	gc_list = NULL;
	entry = &policy->bydst;
	hlist_for_each_entry_continue(policy, entry, bydst) {
		struct dst_entry *dst;

		write_lock(&policy->lock);
		dst = policy->bundles;
		if (dst) {
			struct dst_entry *tail = dst;
			while (tail->next)
				tail = tail->next;
			tail->next = gc_list;
			gc_list = dst;

			policy->bundles = NULL;
		}
		write_unlock(&policy->lock);
	}
	read_unlock_bh(&xfrm_policy_lock);

	while (gc_list) {
		struct dst_entry *dst = gc_list;

		gc_list = dst->next;
		dst_free(dst);
	}

	return 0;
}
EXPORT_SYMBOL(xfrm_policy_insert);

struct xfrm_policy *xfrm_policy_bysel_ctx(u8 type, int dir,
					  struct xfrm_selector *sel,
					  struct xfrm_sec_ctx *ctx, int delete)
{
	struct xfrm_policy *pol, *ret;
	struct hlist_head *chain;
	struct hlist_node *entry;

	write_lock_bh(&xfrm_policy_lock);
	chain = policy_hash_bysel(sel, sel->family, dir);
	ret = NULL;
	hlist_for_each_entry(pol, entry, chain, bydst) {
		if (pol->type == type &&
		    !selector_cmp(sel, &pol->selector) &&
		    xfrm_sec_ctx_match(ctx, pol->security)) {
			xfrm_pol_hold(pol);
			if (delete) {
				hlist_del(&pol->bydst);
				hlist_del(&pol->byidx);
				xfrm_policy_count[dir]--;
			}
			ret = pol;
			break;
		}
	}
	write_unlock_bh(&xfrm_policy_lock);

	if (ret && delete) {
		atomic_inc(&flow_cache_genid);
		xfrm_policy_kill(ret);
	}
	return ret;
}
EXPORT_SYMBOL(xfrm_policy_bysel_ctx);

struct xfrm_policy *xfrm_policy_byid(u8 type, int dir, u32 id, int delete)
{
	struct xfrm_policy *pol, *ret;
	struct hlist_head *chain;
	struct hlist_node *entry;

	write_lock_bh(&xfrm_policy_lock);
	chain = xfrm_policy_byidx + idx_hash(id);
	ret = NULL;
	hlist_for_each_entry(pol, entry, chain, byidx) {
		if (pol->type == type && pol->index == id) {
			xfrm_pol_hold(pol);
			if (delete) {
				hlist_del(&pol->bydst);
				hlist_del(&pol->byidx);
				xfrm_policy_count[dir]--;
			}
			ret = pol;
			break;
		}
	}
	write_unlock_bh(&xfrm_policy_lock);

	if (ret && delete) {
		atomic_inc(&flow_cache_genid);
		xfrm_policy_kill(ret);
	}
	return ret;
}
EXPORT_SYMBOL(xfrm_policy_byid);

void xfrm_policy_flush(u8 type)
{
	int dir;

	write_lock_bh(&xfrm_policy_lock);
	for (dir = 0; dir < XFRM_POLICY_MAX; dir++) {
		struct xfrm_policy *pol;
		struct hlist_node *entry;
		int i, killed;

		killed = 0;
	again1:
		hlist_for_each_entry(pol, entry,
				     &xfrm_policy_inexact[dir], bydst) {
			if (pol->type != type)
				continue;
			hlist_del(&pol->bydst);
			hlist_del(&pol->byidx);
			write_unlock_bh(&xfrm_policy_lock);

			xfrm_policy_kill(pol);
			killed++;

			write_lock_bh(&xfrm_policy_lock);
			goto again1;
		}

		for (i = xfrm_policy_bydst[dir].hmask; i >= 0; i--) {
	again2:
			hlist_for_each_entry(pol, entry,
					     xfrm_policy_bydst[dir].table + i,
					     bydst) {
				if (pol->type != type)
					continue;
				hlist_del(&pol->bydst);
				hlist_del(&pol->byidx);
				write_unlock_bh(&xfrm_policy_lock);

				xfrm_policy_kill(pol);
				killed++;

				write_lock_bh(&xfrm_policy_lock);
				goto again2;
			}
		}

		xfrm_policy_count[dir] -= killed;
	}
	atomic_inc(&flow_cache_genid);
	write_unlock_bh(&xfrm_policy_lock);
}
EXPORT_SYMBOL(xfrm_policy_flush);

int xfrm_policy_walk(u8 type, int (*func)(struct xfrm_policy *, int, int, void*),
		     void *data)
{
	struct xfrm_policy *pol;
	struct hlist_node *entry;
	int dir, count, error;

	read_lock_bh(&xfrm_policy_lock);
	count = 0;
	for (dir = 0; dir < 2*XFRM_POLICY_MAX; dir++) {
		struct hlist_head *table = xfrm_policy_bydst[dir].table;
		int i;

		hlist_for_each_entry(pol, entry,
				     &xfrm_policy_inexact[dir], bydst) {
			if (pol->type == type)
				count++;
		}
		for (i = xfrm_policy_bydst[dir].hmask; i >= 0; i--) {
			hlist_for_each_entry(pol, entry, table + i, bydst) {
				if (pol->type == type)
					count++;
			}
		}
	}

	if (count == 0) {
		error = -ENOENT;
		goto out;
	}

	for (dir = 0; dir < 2*XFRM_POLICY_MAX; dir++) {
		struct hlist_head *table = xfrm_policy_bydst[dir].table;
		int i;

		hlist_for_each_entry(pol, entry,
				     &xfrm_policy_inexact[dir], bydst) {
			if (pol->type != type)
				continue;
			error = func(pol, dir % XFRM_POLICY_MAX, --count, data);
			if (error)
				goto out;
		}
		for (i = xfrm_policy_bydst[dir].hmask; i >= 0; i--) {
			hlist_for_each_entry(pol, entry, table + i, bydst) {
				if (pol->type != type)
					continue;
				error = func(pol, dir % XFRM_POLICY_MAX, --count, data);
				if (error)
					goto out;
			}
		}
	}
	error = 0;
out:
	read_unlock_bh(&xfrm_policy_lock);
	return error;
}
EXPORT_SYMBOL(xfrm_policy_walk);

/*
 * Find policy to apply to this flow.
 *
 * Returns 0 if policy found, else an -errno.
 */
static int xfrm_policy_match(struct xfrm_policy *pol, struct flowi *fl,
			     u8 type, u16 family, int dir)
{
	struct xfrm_selector *sel = &pol->selector;
	int match, ret = -ESRCH;

	if (pol->family != family ||
	    pol->type != type)
		return ret;

	match = xfrm_selector_match(sel, fl, family);
	if (match)
		ret = security_xfrm_policy_lookup(pol, fl->secid, dir);

	return ret;
}

static struct xfrm_policy *xfrm_policy_lookup_bytype(u8 type, struct flowi *fl,
						     u16 family, u8 dir)
{
	int err;
	struct xfrm_policy *pol, *ret;
	xfrm_address_t *daddr, *saddr;
	struct hlist_node *entry;
	struct hlist_head *chain;
	u32 priority = ~0U;

	daddr = xfrm_flowi_daddr(fl, family);
	saddr = xfrm_flowi_saddr(fl, family);
	if (unlikely(!daddr || !saddr))
		return NULL;

	read_lock_bh(&xfrm_policy_lock);
	chain = policy_hash_direct(daddr, saddr, family, dir);
	ret = NULL;
	hlist_for_each_entry(pol, entry, chain, bydst) {
		err = xfrm_policy_match(pol, fl, type, family, dir);
		if (err) {
			if (err == -ESRCH)
				continue;
			else {
				ret = ERR_PTR(err);
				goto fail;
			}
		} else {
			ret = pol;
			priority = ret->priority;
			break;
		}
	}
	chain = &xfrm_policy_inexact[dir];
	hlist_for_each_entry(pol, entry, chain, bydst) {
		err = xfrm_policy_match(pol, fl, type, family, dir);
		if (err) {
			if (err == -ESRCH)
				continue;
			else {
				ret = ERR_PTR(err);
				goto fail;
			}
		} else if (pol->priority < priority) {
			ret = pol;
			break;
		}
	}
	if (ret)
		xfrm_pol_hold(ret);
fail:
	read_unlock_bh(&xfrm_policy_lock);

	return ret;
}

static int xfrm_policy_lookup(struct flowi *fl, u16 family, u8 dir,
			       void **objp, atomic_t **obj_refp)
{
	struct xfrm_policy *pol;
	int err = 0;

#ifdef CONFIG_XFRM_SUB_POLICY
	pol = xfrm_policy_lookup_bytype(XFRM_POLICY_TYPE_SUB, fl, family, dir);
	if (IS_ERR(pol)) {
		err = PTR_ERR(pol);
		pol = NULL;
	}
	if (pol || err)
		goto end;
#endif
	pol = xfrm_policy_lookup_bytype(XFRM_POLICY_TYPE_MAIN, fl, family, dir);
	if (IS_ERR(pol)) {
		err = PTR_ERR(pol);
		pol = NULL;
	}
#ifdef CONFIG_XFRM_SUB_POLICY
end:
#endif
	if ((*objp = (void *) pol) != NULL)
		*obj_refp = &pol->refcnt;
	return err;
}

static inline int policy_to_flow_dir(int dir)
{
	if (XFRM_POLICY_IN == FLOW_DIR_IN &&
 	    XFRM_POLICY_OUT == FLOW_DIR_OUT &&
 	    XFRM_POLICY_FWD == FLOW_DIR_FWD)
 		return dir;
 	switch (dir) {
 	default:
 	case XFRM_POLICY_IN:
 		return FLOW_DIR_IN;
 	case XFRM_POLICY_OUT:
 		return FLOW_DIR_OUT;
 	case XFRM_POLICY_FWD:
 		return FLOW_DIR_FWD;
	};
}

static struct xfrm_policy *xfrm_sk_policy_lookup(struct sock *sk, int dir, struct flowi *fl)
{
	struct xfrm_policy *pol;

	read_lock_bh(&xfrm_policy_lock);
	if ((pol = sk->sk_policy[dir]) != NULL) {
 		int match = xfrm_selector_match(&pol->selector, fl,
						sk->sk_family);
 		int err = 0;

		if (match) {
			err = security_xfrm_policy_lookup(pol, fl->secid,
					policy_to_flow_dir(dir));
			if (!err)
				xfrm_pol_hold(pol);
			else if (err == -ESRCH)
				pol = NULL;
			else
				pol = ERR_PTR(err);
		} else
			pol = NULL;
	}
	read_unlock_bh(&xfrm_policy_lock);
	return pol;
}

static void __xfrm_policy_link(struct xfrm_policy *pol, int dir)
{
	struct hlist_head *chain = policy_hash_bysel(&pol->selector,
						     pol->family, dir);

	hlist_add_head(&pol->bydst, chain);
	hlist_add_head(&pol->byidx, xfrm_policy_byidx+idx_hash(pol->index));
	xfrm_policy_count[dir]++;
	xfrm_pol_hold(pol);

	if (xfrm_bydst_should_resize(dir, NULL))
		schedule_work(&xfrm_hash_work);
}

static struct xfrm_policy *__xfrm_policy_unlink(struct xfrm_policy *pol,
						int dir)
{
	if (hlist_unhashed(&pol->bydst))
		return NULL;

	hlist_del(&pol->bydst);
	hlist_del(&pol->byidx);
	xfrm_policy_count[dir]--;

	return pol;
}

int xfrm_policy_delete(struct xfrm_policy *pol, int dir)
{
	write_lock_bh(&xfrm_policy_lock);
	pol = __xfrm_policy_unlink(pol, dir);
	write_unlock_bh(&xfrm_policy_lock);
	if (pol) {
		if (dir < XFRM_POLICY_MAX)
			atomic_inc(&flow_cache_genid);
		xfrm_policy_kill(pol);
		return 0;
	}
	return -ENOENT;
}
EXPORT_SYMBOL(xfrm_policy_delete);

int xfrm_sk_policy_insert(struct sock *sk, int dir, struct xfrm_policy *pol)
{
	struct xfrm_policy *old_pol;

#ifdef CONFIG_XFRM_SUB_POLICY
	if (pol && pol->type != XFRM_POLICY_TYPE_MAIN)
		return -EINVAL;
#endif

	write_lock_bh(&xfrm_policy_lock);
	old_pol = sk->sk_policy[dir];
	sk->sk_policy[dir] = pol;
	if (pol) {
		pol->curlft.add_time = (unsigned long)xtime.tv_sec;
		pol->index = xfrm_gen_index(pol->type, XFRM_POLICY_MAX+dir);
		__xfrm_policy_link(pol, XFRM_POLICY_MAX+dir);
	}
	if (old_pol)
		__xfrm_policy_unlink(old_pol, XFRM_POLICY_MAX+dir);
	write_unlock_bh(&xfrm_policy_lock);

	if (old_pol) {
		xfrm_policy_kill(old_pol);
	}
	return 0;
}

static struct xfrm_policy *clone_policy(struct xfrm_policy *old, int dir)
{
	struct xfrm_policy *newp = xfrm_policy_alloc(GFP_ATOMIC);

	if (newp) {
		newp->selector = old->selector;
		if (security_xfrm_policy_clone(old, newp)) {
			kfree(newp);
			return NULL;  /* ENOMEM */
		}
		newp->lft = old->lft;
		newp->curlft = old->curlft;
		newp->action = old->action;
		newp->flags = old->flags;
		newp->xfrm_nr = old->xfrm_nr;
		newp->index = old->index;
		newp->type = old->type;
		memcpy(newp->xfrm_vec, old->xfrm_vec,
		       newp->xfrm_nr*sizeof(struct xfrm_tmpl));
		write_lock_bh(&xfrm_policy_lock);
		__xfrm_policy_link(newp, XFRM_POLICY_MAX+dir);
		write_unlock_bh(&xfrm_policy_lock);
		xfrm_pol_put(newp);
	}
	return newp;
}

int __xfrm_sk_clone_policy(struct sock *sk)
{
	struct xfrm_policy *p0 = sk->sk_policy[0],
			   *p1 = sk->sk_policy[1];

	sk->sk_policy[0] = sk->sk_policy[1] = NULL;
	if (p0 && (sk->sk_policy[0] = clone_policy(p0, 0)) == NULL)
		return -ENOMEM;
	if (p1 && (sk->sk_policy[1] = clone_policy(p1, 1)) == NULL)
		return -ENOMEM;
	return 0;
}

static int
xfrm_get_saddr(xfrm_address_t *local, xfrm_address_t *remote,
	       unsigned short family)
{
	int err;
	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);

	if (unlikely(afinfo == NULL))
		return -EINVAL;
	err = afinfo->get_saddr(local, remote);
	xfrm_policy_put_afinfo(afinfo);
	return err;
}

/* Resolve list of templates for the flow, given policy. */

static int
xfrm_tmpl_resolve_one(struct xfrm_policy *policy, struct flowi *fl,
		      struct xfrm_state **xfrm,
		      unsigned short family)
{
	int nx;
	int i, error;
	xfrm_address_t *daddr = xfrm_flowi_daddr(fl, family);
	xfrm_address_t *saddr = xfrm_flowi_saddr(fl, family);
	xfrm_address_t tmp;

	for (nx=0, i = 0; i < policy->xfrm_nr; i++) {
		struct xfrm_state *x;
		xfrm_address_t *remote = daddr;
		xfrm_address_t *local  = saddr;
		struct xfrm_tmpl *tmpl = &policy->xfrm_vec[i];

		if (tmpl->mode == XFRM_MODE_TUNNEL) {
			remote = &tmpl->id.daddr;
			local = &tmpl->saddr;
			family = tmpl->encap_family;
			if (xfrm_addr_any(local, family)) {
				error = xfrm_get_saddr(&tmp, remote, family);
				if (error)
					goto fail;
				local = &tmp;
			}
		}

		x = xfrm_state_find(remote, local, fl, tmpl, policy, &error, family);

		if (x && x->km.state == XFRM_STATE_VALID) {
			xfrm[nx++] = x;
			daddr = remote;
			saddr = local;
			continue;
		}
		if (x) {
			error = (x->km.state == XFRM_STATE_ERROR ?
				 -EINVAL : -EAGAIN);
			xfrm_state_put(x);
		}

		if (!tmpl->optional)
			goto fail;
	}
	return nx;

fail:
	for (nx--; nx>=0; nx--)
		xfrm_state_put(xfrm[nx]);
	return error;
}

static int
xfrm_tmpl_resolve(struct xfrm_policy **pols, int npols, struct flowi *fl,
		  struct xfrm_state **xfrm,
		  unsigned short family)
{
	struct xfrm_state *tp[XFRM_MAX_DEPTH];
	struct xfrm_state **tpp = (npols > 1) ? tp : xfrm;
	int cnx = 0;
	int error;
	int ret;
	int i;

	for (i = 0; i < npols; i++) {
		if (cnx + pols[i]->xfrm_nr >= XFRM_MAX_DEPTH) {
			error = -ENOBUFS;
			goto fail;
		}

		ret = xfrm_tmpl_resolve_one(pols[i], fl, &tpp[cnx], family);
		if (ret < 0) {
			error = ret;
			goto fail;
		} else
			cnx += ret;
	}

	/* found states are sorted for outbound processing */
	if (npols > 1)
		xfrm_state_sort(xfrm, tpp, cnx, family);

	return cnx;

 fail:
	for (cnx--; cnx>=0; cnx--)
		xfrm_state_put(tpp[cnx]);
	return error;

}

/* Check that the bundle accepts the flow and its components are
 * still valid.
 */

static struct dst_entry *
xfrm_find_bundle(struct flowi *fl, struct xfrm_policy *policy, unsigned short family)
{
	struct dst_entry *x;
	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
	if (unlikely(afinfo == NULL))
		return ERR_PTR(-EINVAL);
	x = afinfo->find_bundle(fl, policy);
	xfrm_policy_put_afinfo(afinfo);
	return x;
}

/* Allocate chain of dst_entry's, attach known xfrm's, calculate
 * all the metrics... Shortly, bundle a bundle.
 */

static int
xfrm_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int nx,
		   struct flowi *fl, struct dst_entry **dst_p,
		   unsigned short family)
{
	int err;
	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
	if (unlikely(afinfo == NULL))
		return -EINVAL;
	err = afinfo->bundle_create(policy, xfrm, nx, fl, dst_p);
	xfrm_policy_put_afinfo(afinfo);
	return err;
}


static int stale_bundle(struct dst_entry *dst);

/* Main function: finds/creates a bundle for given flow.
 *
 * At the moment we eat a raw IP route. Mostly to speed up lookups
 * on interfaces with disabled IPsec.
 */
int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
		struct sock *sk, int flags)
{
	struct xfrm_policy *policy;
	struct xfrm_policy *pols[XFRM_POLICY_TYPE_MAX];
	int npols;
	int pol_dead;
	int xfrm_nr;
	int pi;
	struct xfrm_state *xfrm[XFRM_MAX_DEPTH];
	struct dst_entry *dst, *dst_orig = *dst_p;
	int nx = 0;
	int err;
	u32 genid;
	u16 family;
	u8 dir = policy_to_flow_dir(XFRM_POLICY_OUT);

restart:
	genid = atomic_read(&flow_cache_genid);
	policy = NULL;
	for (pi = 0; pi < ARRAY_SIZE(pols); pi++)
		pols[pi] = NULL;
	npols = 0;
	pol_dead = 0;
	xfrm_nr = 0;

	if (sk && sk->sk_policy[1]) {
		policy = xfrm_sk_policy_lookup(sk, XFRM_POLICY_OUT, fl);
		if (IS_ERR(policy))
			return PTR_ERR(policy);
	}

	if (!policy) {
		/* To accelerate a bit...  */
		if ((dst_orig->flags & DST_NOXFRM) ||
		    !xfrm_policy_count[XFRM_POLICY_OUT])
			return 0;

		policy = flow_cache_lookup(fl, dst_orig->ops->family,
					   dir, xfrm_policy_lookup);
		if (IS_ERR(policy))
			return PTR_ERR(policy);
	}

	if (!policy)
		return 0;

	family = dst_orig->ops->family;
	policy->curlft.use_time = (unsigned long)xtime.tv_sec;
	pols[0] = policy;
	npols ++;
	xfrm_nr += pols[0]->xfrm_nr;

	switch (policy->action) {
	case XFRM_POLICY_BLOCK:
		/* Prohibit the flow */
		err = -EPERM;
		goto error;

	case XFRM_POLICY_ALLOW:
#ifndef CONFIG_XFRM_SUB_POLICY
		if (policy->xfrm_nr == 0) {
			/* Flow passes not transformed. */
			xfrm_pol_put(policy);
			return 0;
		}
#endif

		/* Try to find matching bundle.
		 *
		 * LATER: help from flow cache. It is optional, this
		 * is required only for output policy.
		 */
		dst = xfrm_find_bundle(fl, policy, family);
		if (IS_ERR(dst)) {
			err = PTR_ERR(dst);
			goto error;
		}

		if (dst)
			break;

#ifdef CONFIG_XFRM_SUB_POLICY
		if (pols[0]->type != XFRM_POLICY_TYPE_MAIN) {
			pols[1] = xfrm_policy_lookup_bytype(XFRM_POLICY_TYPE_MAIN,
							    fl, family,
							    XFRM_POLICY_OUT);
			if (pols[1]) {
				if (IS_ERR(pols[1])) {
					err = PTR_ERR(pols[1]);
					goto error;
				}
				if (pols[1]->action == XFRM_POLICY_BLOCK) {
					err = -EPERM;
					goto error;
				}
				npols ++;
				xfrm_nr += pols[1]->xfrm_nr;
			}
		}

		/*
		 * Because neither flowi nor bundle information knows about
		 * transformation template size. On more than one policy usage
		 * we can realize whether all of them is bypass or not after
		 * they are searched. See above not-transformed bypass
		 * is surrounded by non-sub policy configuration, too.
		 */
		if (xfrm_nr == 0) {
			/* Flow passes not transformed. */
			xfrm_pols_put(pols, npols);
			return 0;
		}

#endif
		nx = xfrm_tmpl_resolve(pols, npols, fl, xfrm, family);

		if (unlikely(nx<0)) {
			err = nx;
			if (err == -EAGAIN && flags) {
				DECLARE_WAITQUEUE(wait, current);

				add_wait_queue(&km_waitq, &wait);
				set_current_state(TASK_INTERRUPTIBLE);
				schedule();
				set_current_state(TASK_RUNNING);
				remove_wait_queue(&km_waitq, &wait);

				nx = xfrm_tmpl_resolve(pols, npols, fl, xfrm, family);

				if (nx == -EAGAIN && signal_pending(current)) {
					err = -ERESTART;
					goto error;
				}
				if (nx == -EAGAIN ||
				    genid != atomic_read(&flow_cache_genid)) {
					xfrm_pols_put(pols, npols);
					goto restart;
				}
				err = nx;
			}
			if (err < 0)
				goto error;
		}
		if (nx == 0) {
			/* Flow passes not transformed. */
			xfrm_pols_put(pols, npols);
			return 0;
		}

		dst = dst_orig;
		err = xfrm_bundle_create(policy, xfrm, nx, fl, &dst, family);

		if (unlikely(err)) {
			int i;
			for (i=0; i<nx; i++)
				xfrm_state_put(xfrm[i]);
			goto error;
		}

		for (pi = 0; pi < npols; pi++) {
			read_lock_bh(&pols[pi]->lock);
			pol_dead |= pols[pi]->dead;
			read_unlock_bh(&pols[pi]->lock);
		}

		write_lock_bh(&policy->lock);
		if (unlikely(pol_dead || stale_bundle(dst))) {
			/* Wow! While we worked on resolving, this
			 * policy has gone. Retry. It is not paranoia,
			 * we just cannot enlist new bundle to dead object.
			 * We can't enlist stable bundles either.
			 */
			write_unlock_bh(&policy->lock);
			if (dst)
				dst_free(dst);

			err = -EHOSTUNREACH;
			goto error;
		}
		dst->next = policy->bundles;
		policy->bundles = dst;
		dst_hold(dst);
		write_unlock_bh(&policy->lock);
	}
	*dst_p = dst;
	dst_release(dst_orig);
 	xfrm_pols_put(pols, npols);
	return 0;

error:
	dst_release(dst_orig);
	xfrm_pols_put(pols, npols);
	*dst_p = NULL;
	return err;
}
EXPORT_SYMBOL(xfrm_lookup);

static inline int
xfrm_secpath_reject(int idx, struct sk_buff *skb, struct flowi *fl)
{
	struct xfrm_state *x;
	int err;

	if (!skb->sp || idx < 0 || idx >= skb->sp->len)
		return 0;
	x = skb->sp->xvec[idx];
	if (!x->type->reject)
		return 0;
	xfrm_state_hold(x);
	err = x->type->reject(x, skb, fl);
	xfrm_state_put(x);
	return err;
}

/* When skb is transformed back to its "native" form, we have to
 * check policy restrictions. At the moment we make this in maximally
 * stupid way. Shame on me. :-) Of course, connected sockets must
 * have policy cached at them.
 */

static inline int
xfrm_state_ok(struct xfrm_tmpl *tmpl, struct xfrm_state *x, 
	      unsigned short family)
{
	if (xfrm_state_kern(x))
		return tmpl->optional && !xfrm_state_addr_cmp(tmpl, x, family);
	return	x->id.proto == tmpl->id.proto &&
		(x->id.spi == tmpl->id.spi || !tmpl->id.spi) &&
		(x->props.reqid == tmpl->reqid || !tmpl->reqid) &&
		x->props.mode == tmpl->mode &&
		((tmpl->aalgos & (1<<x->props.aalgo)) ||
		 !(xfrm_id_proto_match(tmpl->id.proto, IPSEC_PROTO_ANY))) &&
		!(x->props.mode != XFRM_MODE_TRANSPORT &&
		  xfrm_state_addr_cmp(tmpl, x, family));
}

/*
 * 0 or more than 0 is returned when validation is succeeded (either bypass
 * because of optional transport mode, or next index of the mathced secpath
 * state with the template.
 * -1 is returned when no matching template is found.
 * Otherwise "-2 - errored_index" is returned.
 */
static inline int
xfrm_policy_ok(struct xfrm_tmpl *tmpl, struct sec_path *sp, int start,
	       unsigned short family)
{
	int idx = start;

	if (tmpl->optional) {
		if (tmpl->mode == XFRM_MODE_TRANSPORT)
			return start;
	} else
		start = -1;
	for (; idx < sp->len; idx++) {
		if (xfrm_state_ok(tmpl, sp->xvec[idx], family))
			return ++idx;
		if (sp->xvec[idx]->props.mode != XFRM_MODE_TRANSPORT) {
			if (start == -1)
				start = -2-idx;
			break;
		}
	}
	return start;
}

int
xfrm_decode_session(struct sk_buff *skb, struct flowi *fl, unsigned short family)
{
	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
	int err;

	if (unlikely(afinfo == NULL))
		return -EAFNOSUPPORT;

	afinfo->decode_session(skb, fl);
	err = security_xfrm_decode_session(skb, &fl->secid);
	xfrm_policy_put_afinfo(afinfo);
	return err;
}
EXPORT_SYMBOL(xfrm_decode_session);

static inline int secpath_has_nontransport(struct sec_path *sp, int k, int *idxp)
{
	for (; k < sp->len; k++) {
		if (sp->xvec[k]->props.mode != XFRM_MODE_TRANSPORT) {
			*idxp = k;
			return 1;
		}
	}

	return 0;
}

int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb, 
			unsigned short family)
{
	struct xfrm_policy *pol;
	struct xfrm_policy *pols[XFRM_POLICY_TYPE_MAX];
	int npols = 0;
	int xfrm_nr;
	int pi;
	struct flowi fl;
	u8 fl_dir = policy_to_flow_dir(dir);
	int xerr_idx = -1;

	if (xfrm_decode_session(skb, &fl, family) < 0)
		return 0;
	nf_nat_decode_session(skb, &fl, family);

	/* First, check used SA against their selectors. */
	if (skb->sp) {
		int i;

		for (i=skb->sp->len-1; i>=0; i--) {
			struct xfrm_state *x = skb->sp->xvec[i];
			if (!xfrm_selector_match(&x->sel, &fl, family))
				return 0;
		}
	}

	pol = NULL;
	if (sk && sk->sk_policy[dir]) {
		pol = xfrm_sk_policy_lookup(sk, dir, &fl);
		if (IS_ERR(pol))
			return 0;
	}

	if (!pol)
		pol = flow_cache_lookup(&fl, family, fl_dir,
					xfrm_policy_lookup);

	if (IS_ERR(pol))
		return 0;

	if (!pol) {
		if (skb->sp && secpath_has_nontransport(skb->sp, 0, &xerr_idx)) {
			xfrm_secpath_reject(xerr_idx, skb, &fl);
			return 0;
		}
		return 1;
	}

	pol->curlft.use_time = (unsigned long)xtime.tv_sec;

	pols[0] = pol;
	npols ++;
#ifdef CONFIG_XFRM_SUB_POLICY
	if (pols[0]->type != XFRM_POLICY_TYPE_MAIN) {
		pols[1] = xfrm_policy_lookup_bytype(XFRM_POLICY_TYPE_MAIN,
						    &fl, family,
						    XFRM_POLICY_IN);
		if (pols[1]) {
			if (IS_ERR(pols[1]))
				return 0;
			pols[1]->curlft.use_time = (unsigned long)xtime.tv_sec;
			npols ++;
		}
	}
#endif

	if (pol->action == XFRM_POLICY_ALLOW) {
		struct sec_path *sp;
		static struct sec_path dummy;
		struct xfrm_tmpl *tp[XFRM_MAX_DEPTH];
		struct xfrm_tmpl *stp[XFRM_MAX_DEPTH];
		struct xfrm_tmpl **tpp = tp;
		int ti = 0;
		int i, k;

		if ((sp = skb->sp) == NULL)
			sp = &dummy;

		for (pi = 0; pi < npols; pi++) {
			if (pols[pi] != pol &&
			    pols[pi]->action != XFRM_POLICY_ALLOW)
				goto reject;
			if (ti + pols[pi]->xfrm_nr >= XFRM_MAX_DEPTH)
				goto reject_error;
			for (i = 0; i < pols[pi]->xfrm_nr; i++)
				tpp[ti++] = &pols[pi]->xfrm_vec[i];
		}
		xfrm_nr = ti;
		if (npols > 1) {
			xfrm_tmpl_sort(stp, tpp, xfrm_nr, family);
			tpp = stp;
		}

		/* For each tunnel xfrm, find the first matching tmpl.
		 * For each tmpl before that, find corresponding xfrm.
		 * Order is _important_. Later we will implement
		 * some barriers, but at the moment barriers
		 * are implied between each two transformations.
		 */
		for (i = xfrm_nr-1, k = 0; i >= 0; i--) {
			k = xfrm_policy_ok(tpp[i], sp, k, family);
			if (k < 0) {
				if (k < -1)
					/* "-2 - errored_index" returned */
					xerr_idx = -(2+k);
				goto reject;
			}
		}

		if (secpath_has_nontransport(sp, k, &xerr_idx))
			goto reject;

		xfrm_pols_put(pols, npols);
		return 1;
	}

reject:
	xfrm_secpath_reject(xerr_idx, skb, &fl);
reject_error:
	xfrm_pols_put(pols, npols);
	return 0;
}
EXPORT_SYMBOL(__xfrm_policy_check);

int __xfrm_route_forward(struct sk_buff *skb, unsigned short family)
{
	struct flowi fl;

	if (xfrm_decode_session(skb, &fl, family) < 0)
		return 0;

	return xfrm_lookup(&skb->dst, &fl, NULL, 0) == 0;
}
EXPORT_SYMBOL(__xfrm_route_forward);

/* Optimize later using cookies and generation ids. */

static struct dst_entry *xfrm_dst_check(struct dst_entry *dst, u32 cookie)
{
	/* Code (such as __xfrm4_bundle_create()) sets dst->obsolete
	 * to "-1" to force all XFRM destinations to get validated by
	 * dst_ops->check on every use.  We do this because when a
	 * normal route referenced by an XFRM dst is obsoleted we do
	 * not go looking around for all parent referencing XFRM dsts
	 * so that we can invalidate them.  It is just too much work.
	 * Instead we make the checks here on every use.  For example:
	 *
	 *	XFRM dst A --> IPv4 dst X
	 *
	 * X is the "xdst->route" of A (X is also the "dst->path" of A
	 * in this example).  If X is marked obsolete, "A" will not
	 * notice.  That's what we are validating here via the
	 * stale_bundle() check.
	 *
	 * When a policy's bundle is pruned, we dst_free() the XFRM
	 * dst which causes it's ->obsolete field to be set to a
	 * positive non-zero integer.  If an XFRM dst has been pruned
	 * like this, we want to force a new route lookup.
	 */
	if (dst->obsolete < 0 && !stale_bundle(dst))
		return dst;

	return NULL;
}

static int stale_bundle(struct dst_entry *dst)
{
	return !xfrm_bundle_ok(NULL, (struct xfrm_dst *)dst, NULL, AF_UNSPEC, 0);
}

void xfrm_dst_ifdown(struct dst_entry *dst, struct net_device *dev)
{
	while ((dst = dst->child) && dst->xfrm && dst->dev == dev) {
		dst->dev = &loopback_dev;
		dev_hold(&loopback_dev);
		dev_put(dev);
	}
}
EXPORT_SYMBOL(xfrm_dst_ifdown);

static void xfrm_link_failure(struct sk_buff *skb)
{
	/* Impossible. Such dst must be popped before reaches point of failure. */
	return;
}

static struct dst_entry *xfrm_negative_advice(struct dst_entry *dst)
{
	if (dst) {
		if (dst->obsolete) {
			dst_release(dst);
			dst = NULL;
		}
	}
	return dst;
}

static void prune_one_bundle(struct xfrm_policy *pol, int (*func)(struct dst_entry *), struct dst_entry **gc_list_p)
{
	struct dst_entry *dst, **dstp;

	write_lock(&pol->lock);
	dstp = &pol->bundles;
	while ((dst=*dstp) != NULL) {
		if (func(dst)) {
			*dstp = dst->next;
			dst->next = *gc_list_p;
			*gc_list_p = dst;
		} else {
			dstp = &dst->next;
		}
	}
	write_unlock(&pol->lock);
}

static void xfrm_prune_bundles(int (*func)(struct dst_entry *))
{
	struct dst_entry *gc_list = NULL;
	int dir;

	read_lock_bh(&xfrm_policy_lock);
	for (dir = 0; dir < XFRM_POLICY_MAX * 2; dir++) {
		struct xfrm_policy *pol;
		struct hlist_node *entry;
		struct hlist_head *table;
		int i;

		hlist_for_each_entry(pol, entry,
				     &xfrm_policy_inexact[dir], bydst)
			prune_one_bundle(pol, func, &gc_list);

		table = xfrm_policy_bydst[dir].table;
		for (i = xfrm_policy_bydst[dir].hmask; i >= 0; i--) {
			hlist_for_each_entry(pol, entry, table + i, bydst)
				prune_one_bundle(pol, func, &gc_list);
		}
	}
	read_unlock_bh(&xfrm_policy_lock);

	while (gc_list) {
		struct dst_entry *dst = gc_list;
		gc_list = dst->next;
		dst_free(dst);
	}
}

static int unused_bundle(struct dst_entry *dst)
{
	return !atomic_read(&dst->__refcnt);
}

static void __xfrm_garbage_collect(void)
{
	xfrm_prune_bundles(unused_bundle);
}

static int xfrm_flush_bundles(void)
{
	xfrm_prune_bundles(stale_bundle);
	return 0;
}

void xfrm_init_pmtu(struct dst_entry *dst)
{
	do {
		struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
		u32 pmtu, route_mtu_cached;

		pmtu = dst_mtu(dst->child);
		xdst->child_mtu_cached = pmtu;

		pmtu = xfrm_state_mtu(dst->xfrm, pmtu);

		route_mtu_cached = dst_mtu(xdst->route);
		xdst->route_mtu_cached = route_mtu_cached;

		if (pmtu > route_mtu_cached)
			pmtu = route_mtu_cached;

		dst->metrics[RTAX_MTU-1] = pmtu;
	} while ((dst = dst->next));
}

EXPORT_SYMBOL(xfrm_init_pmtu);

/* Check that the bundle accepts the flow and its components are
 * still valid.
 */

int xfrm_bundle_ok(struct xfrm_policy *pol, struct xfrm_dst *first,
		struct flowi *fl, int family, int strict)
{
	struct dst_entry *dst = &first->u.dst;
	struct xfrm_dst *last;
	u32 mtu;

	if (!dst_check(dst->path, ((struct xfrm_dst *)dst)->path_cookie) ||
	    (dst->dev && !netif_running(dst->dev)))
		return 0;

	last = NULL;

	do {
		struct xfrm_dst *xdst = (struct xfrm_dst *)dst;

		if (fl && !xfrm_selector_match(&dst->xfrm->sel, fl, family))
			return 0;
		if (fl && pol &&
		    !security_xfrm_state_pol_flow_match(dst->xfrm, pol, fl))
			return 0;
		if (dst->xfrm->km.state != XFRM_STATE_VALID)
			return 0;
		if (xdst->genid != dst->xfrm->genid)
			return 0;

		if (strict && fl && dst->xfrm->props.mode != XFRM_MODE_TUNNEL &&
		    !xfrm_state_addr_flow_check(dst->xfrm, fl, family))
			return 0;

		mtu = dst_mtu(dst->child);
		if (xdst->child_mtu_cached != mtu) {
			last = xdst;
			xdst->child_mtu_cached = mtu;
		}

		if (!dst_check(xdst->route, xdst->route_cookie))
			return 0;
		mtu = dst_mtu(xdst->route);
		if (xdst->route_mtu_cached != mtu) {
			last = xdst;
			xdst->route_mtu_cached = mtu;
		}

		dst = dst->child;
	} while (dst->xfrm);

	if (likely(!last))
		return 1;

	mtu = last->child_mtu_cached;
	for (;;) {
		dst = &last->u.dst;

		mtu = xfrm_state_mtu(dst->xfrm, mtu);
		if (mtu > last->route_mtu_cached)
			mtu = last->route_mtu_cached;
		dst->metrics[RTAX_MTU-1] = mtu;

		if (last == first)
			break;

		last = last->u.next;
		last->child_mtu_cached = mtu;
	}

	return 1;
}

EXPORT_SYMBOL(xfrm_bundle_ok);

int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo)
{
	int err = 0;
	if (unlikely(afinfo == NULL))
		return -EINVAL;
	if (unlikely(afinfo->family >= NPROTO))
		return -EAFNOSUPPORT;
	write_lock_bh(&xfrm_policy_afinfo_lock);
	if (unlikely(xfrm_policy_afinfo[afinfo->family] != NULL))
		err = -ENOBUFS;
	else {
		struct dst_ops *dst_ops = afinfo->dst_ops;
		if (likely(dst_ops->kmem_cachep == NULL))
			dst_ops->kmem_cachep = xfrm_dst_cache;
		if (likely(dst_ops->check == NULL))
			dst_ops->check = xfrm_dst_check;
		if (likely(dst_ops->negative_advice == NULL))
			dst_ops->negative_advice = xfrm_negative_advice;
		if (likely(dst_ops->link_failure == NULL))
			dst_ops->link_failure = xfrm_link_failure;
		if (likely(afinfo->garbage_collect == NULL))
			afinfo->garbage_collect = __xfrm_garbage_collect;
		xfrm_policy_afinfo[afinfo->family] = afinfo;
	}
	write_unlock_bh(&xfrm_policy_afinfo_lock);
	return err;
}
EXPORT_SYMBOL(xfrm_policy_register_afinfo);

int xfrm_policy_unregister_afinfo(struct xfrm_policy_afinfo *afinfo)
{
	int err = 0;
	if (unlikely(afinfo == NULL))
		return -EINVAL;
	if (unlikely(afinfo->family >= NPROTO))
		return -EAFNOSUPPORT;
	write_lock_bh(&xfrm_policy_afinfo_lock);
	if (likely(xfrm_policy_afinfo[afinfo->family] != NULL)) {
		if (unlikely(xfrm_policy_afinfo[afinfo->family] != afinfo))
			err = -EINVAL;
		else {
			struct dst_ops *dst_ops = afinfo->dst_ops;
			xfrm_policy_afinfo[afinfo->family] = NULL;
			dst_ops->kmem_cachep = NULL;
			dst_ops->check = NULL;
			dst_ops->negative_advice = NULL;
			dst_ops->link_failure = NULL;
			afinfo->garbage_collect = NULL;
		}
	}
	write_unlock_bh(&xfrm_policy_afinfo_lock);
	return err;
}
EXPORT_SYMBOL(xfrm_policy_unregister_afinfo);

static struct xfrm_policy_afinfo *xfrm_policy_get_afinfo(unsigned short family)
{
	struct xfrm_policy_afinfo *afinfo;
	if (unlikely(family >= NPROTO))
		return NULL;
	read_lock(&xfrm_policy_afinfo_lock);
	afinfo = xfrm_policy_afinfo[family];
	if (unlikely(!afinfo))
		read_unlock(&xfrm_policy_afinfo_lock);
	return afinfo;
}

static void xfrm_policy_put_afinfo(struct xfrm_policy_afinfo *afinfo)
{
	read_unlock(&xfrm_policy_afinfo_lock);
}

static struct xfrm_policy_afinfo *xfrm_policy_lock_afinfo(unsigned int family)
{
	struct xfrm_policy_afinfo *afinfo;
	if (unlikely(family >= NPROTO))
		return NULL;
	write_lock_bh(&xfrm_policy_afinfo_lock);
	afinfo = xfrm_policy_afinfo[family];
	if (unlikely(!afinfo))
		write_unlock_bh(&xfrm_policy_afinfo_lock);
	return afinfo;
}

static void xfrm_policy_unlock_afinfo(struct xfrm_policy_afinfo *afinfo)
{
	write_unlock_bh(&xfrm_policy_afinfo_lock);
}

static int xfrm_dev_event(struct notifier_block *this, unsigned long event, void *ptr)
{
	switch (event) {
	case NETDEV_DOWN:
		xfrm_flush_bundles();
	}
	return NOTIFY_DONE;
}

static struct notifier_block xfrm_dev_notifier = {
	xfrm_dev_event,
	NULL,
	0
};

static void __init xfrm_policy_init(void)
{
	unsigned int hmask, sz;
	int dir;

	xfrm_dst_cache = kmem_cache_create("xfrm_dst_cache",
					   sizeof(struct xfrm_dst),
					   0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
					   NULL, NULL);

	hmask = 8 - 1;
	sz = (hmask+1) * sizeof(struct hlist_head);

	xfrm_policy_byidx = xfrm_hash_alloc(sz);
	xfrm_idx_hmask = hmask;
	if (!xfrm_policy_byidx)
		panic("XFRM: failed to allocate byidx hash\n");

	for (dir = 0; dir < XFRM_POLICY_MAX * 2; dir++) {
		struct xfrm_policy_hash *htab;

		INIT_HLIST_HEAD(&xfrm_policy_inexact[dir]);

		htab = &xfrm_policy_bydst[dir];
		htab->table = xfrm_hash_alloc(sz);
		htab->hmask = hmask;
		if (!htab->table)
			panic("XFRM: failed to allocate bydst hash\n");
	}

	INIT_WORK(&xfrm_policy_gc_work, xfrm_policy_gc_task);
	register_netdevice_notifier(&xfrm_dev_notifier);
}

void __init xfrm_init(void)
{
	xfrm_state_init();
	xfrm_policy_init();
	xfrm_input_init();
}