/*
 * 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/err.h>
#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 <linux/cpu.h>
#include <linux/audit.h>
#include <net/dst.h>
#include <net/flow.h>
#include <net/xfrm.h>
#include <net/ip.h>
#ifdef CONFIG_XFRM_STATISTICS
#include <net/snmp.h>
#endif

#include "xfrm_hash.h"

#define XFRM_QUEUE_TMO_MIN ((unsigned)(HZ/10))
#define XFRM_QUEUE_TMO_MAX ((unsigned)(60*HZ))
#define XFRM_MAX_QUEUE_LEN      100

struct xfrm_flo {
        struct dst_entry *dst_orig;
        u8 flags;
};

static DEFINE_PER_CPU(struct xfrm_dst *, xfrm_last_dst);
static struct work_struct *xfrm_pcpu_work __read_mostly;
static DEFINE_SPINLOCK(xfrm_policy_afinfo_lock);
static struct xfrm_policy_afinfo const __rcu *xfrm_policy_afinfo[AF_INET6 + 1]
                                                __read_mostly;

static struct kmem_cache *xfrm_dst_cache __read_mostly;
static __read_mostly seqcount_t xfrm_policy_hash_generation;

static void xfrm_init_pmtu(struct xfrm_dst **bundle, int nr);
static int stale_bundle(struct dst_entry *dst);
static int xfrm_bundle_ok(struct xfrm_dst *xdst);
static void xfrm_policy_queue_process(struct timer_list *t);

static void __xfrm_policy_link(struct xfrm_policy *pol, int dir);
static struct xfrm_policy *__xfrm_policy_unlink(struct xfrm_policy *pol,
                                                int dir);

static inline bool xfrm_pol_hold_rcu(struct xfrm_policy *policy)
{
        return refcount_inc_not_zero(&policy->refcnt);
}

static inline bool
__xfrm4_selector_match(const struct xfrm_selector *sel, const struct flowi *fl)
{
        const struct flowi4 *fl4 = &fl->u.ip4;

        return  addr4_match(fl4->daddr, sel->daddr.a4, sel->prefixlen_d) &&
                addr4_match(fl4->saddr, sel->saddr.a4, sel->prefixlen_s) &&
                !((xfrm_flowi_dport(fl, &fl4->uli) ^ sel->dport) & sel->dport_mask) &&
                !((xfrm_flowi_sport(fl, &fl4->uli) ^ sel->sport) & sel->sport_mask) &&
                (fl4->flowi4_proto == sel->proto || !sel->proto) &&
                (fl4->flowi4_oif == sel->ifindex || !sel->ifindex);
}

static inline bool
__xfrm6_selector_match(const struct xfrm_selector *sel, const struct flowi *fl)
{
        const struct flowi6 *fl6 = &fl->u.ip6;

        return  addr_match(&fl6->daddr, &sel->daddr, sel->prefixlen_d) &&
                addr_match(&fl6->saddr, &sel->saddr, sel->prefixlen_s) &&
                !((xfrm_flowi_dport(fl, &fl6->uli) ^ sel->dport) & sel->dport_mask) &&
                !((xfrm_flowi_sport(fl, &fl6->uli) ^ sel->sport) & sel->sport_mask) &&
                (fl6->flowi6_proto == sel->proto || !sel->proto) &&
                (fl6->flowi6_oif == sel->ifindex || !sel->ifindex);
}

bool xfrm_selector_match(const struct xfrm_selector *sel, const 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 false;
}

static const struct xfrm_policy_afinfo *xfrm_policy_get_afinfo(unsigned short family)
{
        const struct xfrm_policy_afinfo *afinfo;

        if (unlikely(family >= ARRAY_SIZE(xfrm_policy_afinfo)))
                return NULL;
        rcu_read_lock();
        afinfo = rcu_dereference(xfrm_policy_afinfo[family]);
        if (unlikely(!afinfo))
                rcu_read_unlock();
        return afinfo;
}

struct dst_entry *__xfrm_dst_lookup(struct net *net, int tos, int oif,
                                    const xfrm_address_t *saddr,
                                    const xfrm_address_t *daddr,
                                    int family, u32 mark)
{
        const struct xfrm_policy_afinfo *afinfo;
        struct dst_entry *dst;

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

        dst = afinfo->dst_lookup(net, tos, oif, saddr, daddr, mark);

        rcu_read_unlock();

        return dst;
}
EXPORT_SYMBOL(__xfrm_dst_lookup);

static inline struct dst_entry *xfrm_dst_lookup(struct xfrm_state *x,
                                                int tos, int oif,
                                                xfrm_address_t *prev_saddr,
                                                xfrm_address_t *prev_daddr,
                                                int family, u32 mark)
{
        struct net *net = xs_net(x);
        xfrm_address_t *saddr = &x->props.saddr;
        xfrm_address_t *daddr = &x->id.daddr;
        struct dst_entry *dst;

        if (x->type->flags & XFRM_TYPE_LOCAL_COADDR) {
                saddr = x->coaddr;
                daddr = prev_daddr;
        }
        if (x->type->flags & XFRM_TYPE_REMOTE_COADDR) {
                saddr = prev_saddr;
                daddr = x->coaddr;
        }

        dst = __xfrm_dst_lookup(net, tos, oif, saddr, daddr, family, mark);

        if (!IS_ERR(dst)) {
                if (prev_saddr != saddr)
                        memcpy(prev_saddr, saddr,  sizeof(*prev_saddr));
                if (prev_daddr != daddr)
                        memcpy(prev_daddr, daddr,  sizeof(*prev_daddr));
        }

        return dst;
}

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(struct timer_list *t)
{
        struct xfrm_policy *xp = from_timer(xp, t, timer);
        unsigned long now = get_seconds();
        long next = LONG_MAX;
        int warn = 0;
        int dir;

        read_lock(&xp->lock);

        if (unlikely(xp->walk.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(struct net *net, gfp_t gfp)
{
        struct xfrm_policy *policy;

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

        if (policy) {
                write_pnet(&policy->xp_net, net);
                INIT_LIST_HEAD(&policy->walk.all);
                INIT_HLIST_NODE(&policy->bydst);
                INIT_HLIST_NODE(&policy->byidx);
                rwlock_init(&policy->lock);
                refcount_set(&policy->refcnt, 1);
                skb_queue_head_init(&policy->polq.hold_queue);
                timer_setup(&policy->timer, xfrm_policy_timer, 0);
                timer_setup(&policy->polq.hold_timer,
                            xfrm_policy_queue_process, 0);
        }
        return policy;
}
EXPORT_SYMBOL(xfrm_policy_alloc);

static void xfrm_policy_destroy_rcu(struct rcu_head *head)
{
        struct xfrm_policy *policy = container_of(head, struct xfrm_policy, rcu);

        security_xfrm_policy_free(policy->security);
        kfree(policy);
}

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

void xfrm_policy_destroy(struct xfrm_policy *policy)
{
        BUG_ON(!policy->walk.dead);

        if (del_timer(&policy->timer) || del_timer(&policy->polq.hold_timer))
                BUG();

        call_rcu(&policy->rcu, xfrm_policy_destroy_rcu);
}
EXPORT_SYMBOL(xfrm_policy_destroy);

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

static void xfrm_policy_kill(struct xfrm_policy *policy)
{
        policy->walk.dead = 1;

        atomic_inc(&policy->genid);

        if (del_timer(&policy->polq.hold_timer))
                xfrm_pol_put(policy);
        skb_queue_purge(&policy->polq.hold_queue);

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

        xfrm_pol_put(policy);
}

static unsigned int xfrm_policy_hashmax __read_mostly = 1 * 1024 * 1024;

static inline unsigned int idx_hash(struct net *net, u32 index)
{
        return __idx_hash(index, net->xfrm.policy_idx_hmask);
}

/* calculate policy hash thresholds */
static void __get_hash_thresh(struct net *net,
                              unsigned short family, int dir,
                              u8 *dbits, u8 *sbits)
{
        switch (family) {
        case AF_INET:
                *dbits = net->xfrm.policy_bydst[dir].dbits4;
                *sbits = net->xfrm.policy_bydst[dir].sbits4;
                break;

        case AF_INET6:
                *dbits = net->xfrm.policy_bydst[dir].dbits6;
                *sbits = net->xfrm.policy_bydst[dir].sbits6;
                break;

        default:
                *dbits = 0;
                *sbits = 0;
        }
}

static struct hlist_head *policy_hash_bysel(struct net *net,
                                            const struct xfrm_selector *sel,
                                            unsigned short family, int dir)
{
        unsigned int hmask = net->xfrm.policy_bydst[dir].hmask;
        unsigned int hash;
        u8 dbits;
        u8 sbits;

        __get_hash_thresh(net, family, dir, &dbits, &sbits);
        hash = __sel_hash(sel, family, hmask, dbits, sbits);

        if (hash == hmask + 1)
                return &net->xfrm.policy_inexact[dir];

        return rcu_dereference_check(net->xfrm.policy_bydst[dir].table,
                     lockdep_is_held(&net->xfrm.xfrm_policy_lock)) + hash;
}

static struct hlist_head *policy_hash_direct(struct net *net,
                                             const xfrm_address_t *daddr,
                                             const xfrm_address_t *saddr,
                                             unsigned short family, int dir)
{
        unsigned int hmask = net->xfrm.policy_bydst[dir].hmask;
        unsigned int hash;
        u8 dbits;
        u8 sbits;

        __get_hash_thresh(net, family, dir, &dbits, &sbits);
        hash = __addr_hash(daddr, saddr, family, hmask, dbits, sbits);

        return rcu_dereference_check(net->xfrm.policy_bydst[dir].table,
                     lockdep_is_held(&net->xfrm.xfrm_policy_lock)) + hash;
}

static void xfrm_dst_hash_transfer(struct net *net,
                                   struct hlist_head *list,
                                   struct hlist_head *ndsttable,
                                   unsigned int nhashmask,
                                   int dir)
{
        struct hlist_node *tmp, *entry0 = NULL;
        struct xfrm_policy *pol;
        unsigned int h0 = 0;
        u8 dbits;
        u8 sbits;

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

                __get_hash_thresh(net, pol->family, dir, &dbits, &sbits);
                h = __addr_hash(&pol->selector.daddr, &pol->selector.saddr,
                                pol->family, nhashmask, dbits, sbits);
                if (!entry0) {
                        hlist_del_rcu(&pol->bydst);
                        hlist_add_head_rcu(&pol->bydst, ndsttable + h);
                        h0 = h;
                } else {
                        if (h != h0)
                                continue;
                        hlist_del_rcu(&pol->bydst);
                        hlist_add_behind_rcu(&pol->bydst, entry0);
                }
                entry0 = &pol->bydst;
        }
        if (!hlist_empty(list)) {
                entry0 = NULL;
                goto redo;
        }
}

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

        hlist_for_each_entry_safe(pol, 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(struct net *net, int dir)
{
        unsigned int hmask = net->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 *ndst = xfrm_hash_alloc(nsize);
        struct hlist_head *odst;
        int i;

        if (!ndst)
                return;

        spin_lock_bh(&net->xfrm.xfrm_policy_lock);
        write_seqcount_begin(&xfrm_policy_hash_generation);

        odst = rcu_dereference_protected(net->xfrm.policy_bydst[dir].table,
                                lockdep_is_held(&net->xfrm.xfrm_policy_lock));

        odst = rcu_dereference_protected(net->xfrm.policy_bydst[dir].table,
                                lockdep_is_held(&net->xfrm.xfrm_policy_lock));

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

        rcu_assign_pointer(net->xfrm.policy_bydst[dir].table, ndst);
        net->xfrm.policy_bydst[dir].hmask = nhashmask;

        write_seqcount_end(&xfrm_policy_hash_generation);
        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);

        synchronize_rcu();

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

static void xfrm_byidx_resize(struct net *net, int total)
{
        unsigned int hmask = net->xfrm.policy_idx_hmask;
        unsigned int nhashmask = xfrm_new_hash_mask(hmask);
        unsigned int nsize = (nhashmask + 1) * sizeof(struct hlist_head);
        struct hlist_head *oidx = net->xfrm.policy_byidx;
        struct hlist_head *nidx = xfrm_hash_alloc(nsize);
        int i;

        if (!nidx)
                return;

        spin_lock_bh(&net->xfrm.xfrm_policy_lock);

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

        net->xfrm.policy_byidx = nidx;
        net->xfrm.policy_idx_hmask = nhashmask;

        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);

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

static inline int xfrm_bydst_should_resize(struct net *net, int dir, int *total)
{
        unsigned int cnt = net->xfrm.policy_count[dir];
        unsigned int hmask = net->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(struct net *net, int total)
{
        unsigned int hmask = net->xfrm.policy_idx_hmask;

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

        return 0;
}

void xfrm_spd_getinfo(struct net *net, struct xfrmk_spdinfo *si)
{
        si->incnt = net->xfrm.policy_count[XFRM_POLICY_IN];
        si->outcnt = net->xfrm.policy_count[XFRM_POLICY_OUT];
        si->fwdcnt = net->xfrm.policy_count[XFRM_POLICY_FWD];
        si->inscnt = net->xfrm.policy_count[XFRM_POLICY_IN+XFRM_POLICY_MAX];
        si->outscnt = net->xfrm.policy_count[XFRM_POLICY_OUT+XFRM_POLICY_MAX];
        si->fwdscnt = net->xfrm.policy_count[XFRM_POLICY_FWD+XFRM_POLICY_MAX];
        si->spdhcnt = net->xfrm.policy_idx_hmask;
        si->spdhmcnt = xfrm_policy_hashmax;
}
EXPORT_SYMBOL(xfrm_spd_getinfo);

static DEFINE_MUTEX(hash_resize_mutex);
static void xfrm_hash_resize(struct work_struct *work)
{
        struct net *net = container_of(work, struct net, xfrm.policy_hash_work);
        int dir, total;

        mutex_lock(&hash_resize_mutex);

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

        mutex_unlock(&hash_resize_mutex);
}

static void xfrm_hash_rebuild(struct work_struct *work)
{
        struct net *net = container_of(work, struct net,
                                       xfrm.policy_hthresh.work);
        unsigned int hmask;
        struct xfrm_policy *pol;
        struct xfrm_policy *policy;
        struct hlist_head *chain;
        struct hlist_head *odst;
        struct hlist_node *newpos;
        int i;
        int dir;
        unsigned seq;
        u8 lbits4, rbits4, lbits6, rbits6;

        mutex_lock(&hash_resize_mutex);

        /* read selector prefixlen thresholds */
        do {
                seq = read_seqbegin(&net->xfrm.policy_hthresh.lock);

                lbits4 = net->xfrm.policy_hthresh.lbits4;
                rbits4 = net->xfrm.policy_hthresh.rbits4;
                lbits6 = net->xfrm.policy_hthresh.lbits6;
                rbits6 = net->xfrm.policy_hthresh.rbits6;
        } while (read_seqretry(&net->xfrm.policy_hthresh.lock, seq));

        spin_lock_bh(&net->xfrm.xfrm_policy_lock);

        /* reset the bydst and inexact table in all directions */
        for (dir = 0; dir < XFRM_POLICY_MAX; dir++) {
                INIT_HLIST_HEAD(&net->xfrm.policy_inexact[dir]);
                hmask = net->xfrm.policy_bydst[dir].hmask;
                odst = net->xfrm.policy_bydst[dir].table;
                for (i = hmask; i >= 0; i--)
                        INIT_HLIST_HEAD(odst + i);
                if ((dir & XFRM_POLICY_MASK) == XFRM_POLICY_OUT) {
                        /* dir out => dst = remote, src = local */
                        net->xfrm.policy_bydst[dir].dbits4 = rbits4;
                        net->xfrm.policy_bydst[dir].sbits4 = lbits4;
                        net->xfrm.policy_bydst[dir].dbits6 = rbits6;
                        net->xfrm.policy_bydst[dir].sbits6 = lbits6;
                } else {
                        /* dir in/fwd => dst = local, src = remote */
                        net->xfrm.policy_bydst[dir].dbits4 = lbits4;
                        net->xfrm.policy_bydst[dir].sbits4 = rbits4;
                        net->xfrm.policy_bydst[dir].dbits6 = lbits6;
                        net->xfrm.policy_bydst[dir].sbits6 = rbits6;
                }
        }

        /* re-insert all policies by order of creation */
        list_for_each_entry_reverse(policy, &net->xfrm.policy_all, walk.all) {
                if (policy->walk.dead ||
                    xfrm_policy_id2dir(policy->index) >= XFRM_POLICY_MAX) {
                        /* skip socket policies */
                        continue;
                }
                newpos = NULL;
                chain = policy_hash_bysel(net, &policy->selector,
                                          policy->family,
                                          xfrm_policy_id2dir(policy->index));
                hlist_for_each_entry(pol, chain, bydst) {
                        if (policy->priority >= pol->priority)
                                newpos = &pol->bydst;
                        else
                                break;
                }
                if (newpos)
                        hlist_add_behind(&policy->bydst, newpos);
                else
                        hlist_add_head(&policy->bydst, chain);
        }

        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);

        mutex_unlock(&hash_resize_mutex);
}

void xfrm_policy_hash_rebuild(struct net *net)
{
        schedule_work(&net->xfrm.policy_hthresh.work);
}
EXPORT_SYMBOL(xfrm_policy_hash_rebuild);

/* 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(struct net *net, int dir, u32 index)
{
        static u32 idx_generator;

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

                if (!index) {
                        idx = (idx_generator | dir);
                        idx_generator += 8;
                } else {
                        idx = index;
                        index = 0;
                }

                if (idx == 0)
                        idx = 8;
                list = net->xfrm.policy_byidx + idx_hash(net, idx);
                found = 0;
                hlist_for_each_entry(p, 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;
}

static void xfrm_policy_requeue(struct xfrm_policy *old,
                                struct xfrm_policy *new)
{
        struct xfrm_policy_queue *pq = &old->polq;
        struct sk_buff_head list;

        if (skb_queue_empty(&pq->hold_queue))
                return;

        __skb_queue_head_init(&list);

        spin_lock_bh(&pq->hold_queue.lock);
        skb_queue_splice_init(&pq->hold_queue, &list);
        if (del_timer(&pq->hold_timer))
                xfrm_pol_put(old);
        spin_unlock_bh(&pq->hold_queue.lock);

        pq = &new->polq;

        spin_lock_bh(&pq->hold_queue.lock);
        skb_queue_splice(&list, &pq->hold_queue);
        pq->timeout = XFRM_QUEUE_TMO_MIN;
        if (!mod_timer(&pq->hold_timer, jiffies))
                xfrm_pol_hold(new);
        spin_unlock_bh(&pq->hold_queue.lock);
}

static bool xfrm_policy_mark_match(struct xfrm_policy *policy,
                                   struct xfrm_policy *pol)
{
        u32 mark = policy->mark.v & policy->mark.m;

        if (policy->mark.v == pol->mark.v && policy->mark.m == pol->mark.m)
                return true;

        if ((mark & pol->mark.m) == pol->mark.v &&
            policy->priority == pol->priority)
                return true;

        return false;
}

int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl)
{
        struct net *net = xp_net(policy);
        struct xfrm_policy *pol;
        struct xfrm_policy *delpol;
        struct hlist_head *chain;
        struct hlist_node *newpos;

        spin_lock_bh(&net->xfrm.xfrm_policy_lock);
        chain = policy_hash_bysel(net, &policy->selector, policy->family, dir);
        delpol = NULL;
        newpos = NULL;
        hlist_for_each_entry(pol, chain, bydst) {
                if (pol->type == policy->type &&
                    !selector_cmp(&pol->selector, &policy->selector) &&
                    xfrm_policy_mark_match(policy, pol) &&
                    xfrm_sec_ctx_match(pol->security, policy->security) &&
                    !WARN_ON(delpol)) {
                        if (excl) {
                                spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
                                return -EEXIST;
                        }
                        delpol = pol;
                        if (policy->priority > pol->priority)
                                continue;
                } else if (policy->priority >= pol->priority) {
                        newpos = &pol->bydst;
                        continue;
                }
                if (delpol)
                        break;
        }
        if (newpos)
                hlist_add_behind(&policy->bydst, newpos);
        else
                hlist_add_head(&policy->bydst, chain);
        __xfrm_policy_link(policy, dir);

        /* After previous checking, family can either be AF_INET or AF_INET6 */
        if (policy->family == AF_INET)
                rt_genid_bump_ipv4(net);
        else
                rt_genid_bump_ipv6(net);

        if (delpol) {
                xfrm_policy_requeue(delpol, policy);
                __xfrm_policy_unlink(delpol, dir);
        }
        policy->index = delpol ? delpol->index : xfrm_gen_index(net, dir, policy->index);
        hlist_add_head(&policy->byidx, net->xfrm.policy_byidx+idx_hash(net, policy->index));
        policy->curlft.add_time = get_seconds();
        policy->curlft.use_time = 0;
        if (!mod_timer(&policy->timer, jiffies + HZ))
                xfrm_pol_hold(policy);
        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);

        if (delpol)
                xfrm_policy_kill(delpol);
        else if (xfrm_bydst_should_resize(net, dir, NULL))
                schedule_work(&net->xfrm.policy_hash_work);

        return 0;
}
EXPORT_SYMBOL(xfrm_policy_insert);

struct xfrm_policy *xfrm_policy_bysel_ctx(struct net *net, u32 mark, u8 type,
                                          int dir, struct xfrm_selector *sel,
                                          struct xfrm_sec_ctx *ctx, int delete,
                                          int *err)
{
        struct xfrm_policy *pol, *ret;
        struct hlist_head *chain;

        *err = 0;
        spin_lock_bh(&net->xfrm.xfrm_policy_lock);
        chain = policy_hash_bysel(net, sel, sel->family, dir);
        ret = NULL;
        hlist_for_each_entry(pol, chain, bydst) {
                if (pol->type == type &&
                    (mark & pol->mark.m) == pol->mark.v &&
                    !selector_cmp(sel, &pol->selector) &&
                    xfrm_sec_ctx_match(ctx, pol->security)) {
                        xfrm_pol_hold(pol);
                        if (delete) {
                                *err = security_xfrm_policy_delete(
                                                                pol->security);
                                if (*err) {
                                        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
                                        return pol;
                                }
                                __xfrm_policy_unlink(pol, dir);
                        }
                        ret = pol;
                        break;
                }
        }
        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);

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

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

        *err = -ENOENT;
        if (xfrm_policy_id2dir(id) != dir)
                return NULL;

        *err = 0;
        spin_lock_bh(&net->xfrm.xfrm_policy_lock);
        chain = net->xfrm.policy_byidx + idx_hash(net, id);
        ret = NULL;
        hlist_for_each_entry(pol, chain, byidx) {
                if (pol->type == type && pol->index == id &&
                    (mark & pol->mark.m) == pol->mark.v) {
                        xfrm_pol_hold(pol);
                        if (delete) {
                                *err = security_xfrm_policy_delete(
                                                                pol->security);
                                if (*err) {
                                        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
                                        return pol;
                                }
                                __xfrm_policy_unlink(pol, dir);
                        }
                        ret = pol;
                        break;
                }
        }
        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);

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

#ifdef CONFIG_SECURITY_NETWORK_XFRM
static inline int
xfrm_policy_flush_secctx_check(struct net *net, u8 type, bool task_valid)
{
        int dir, err = 0;

        for (dir = 0; dir < XFRM_POLICY_MAX; dir++) {
                struct xfrm_policy *pol;
                int i;

                hlist_for_each_entry(pol,
                                     &net->xfrm.policy_inexact[dir], bydst) {
                        if (pol->type != type)
                                continue;
                        err = security_xfrm_policy_delete(pol->security);
                        if (err) {
                                xfrm_audit_policy_delete(pol, 0, task_valid);
                                return err;
                        }
                }
                for (i = net->xfrm.policy_bydst[dir].hmask; i >= 0; i--) {
                        hlist_for_each_entry(pol,
                                             net->xfrm.policy_bydst[dir].table + i,
                                             bydst) {
                                if (pol->type != type)
                                        continue;
                                err = security_xfrm_policy_delete(
                                                                pol->security);
                                if (err) {
                                        xfrm_audit_policy_delete(pol, 0,
                                                                 task_valid);
                                        return err;
                                }
                        }
                }
        }
        return err;
}
#else
static inline int
xfrm_policy_flush_secctx_check(struct net *net, u8 type, bool task_valid)
{
        return 0;
}
#endif

int xfrm_policy_flush(struct net *net, u8 type, bool task_valid)
{
        int dir, err = 0, cnt = 0;

        spin_lock_bh(&net->xfrm.xfrm_policy_lock);

        err = xfrm_policy_flush_secctx_check(net, type, task_valid);
        if (err)
                goto out;

        for (dir = 0; dir < XFRM_POLICY_MAX; dir++) {
                struct xfrm_policy *pol;
                int i;

        again1:
                hlist_for_each_entry(pol,
                                     &net->xfrm.policy_inexact[dir], bydst) {
                        if (pol->type != type)
                                continue;
                        __xfrm_policy_unlink(pol, dir);
                        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
                        cnt++;

                        xfrm_audit_policy_delete(pol, 1, task_valid);

                        xfrm_policy_kill(pol);

                        spin_lock_bh(&net->xfrm.xfrm_policy_lock);
                        goto again1;
                }

                for (i = net->xfrm.policy_bydst[dir].hmask; i >= 0; i--) {
        again2:
                        hlist_for_each_entry(pol,
                                             net->xfrm.policy_bydst[dir].table + i,
                                             bydst) {
                                if (pol->type != type)
                                        continue;
                                __xfrm_policy_unlink(pol, dir);
                                spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
                                cnt++;

                                xfrm_audit_policy_delete(pol, 1, task_valid);
                                xfrm_policy_kill(pol);

                                spin_lock_bh(&net->xfrm.xfrm_policy_lock);
                                goto again2;
                        }
                }

        }
        if (!cnt)
                err = -ESRCH;
out:
        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
        return err;
}
EXPORT_SYMBOL(xfrm_policy_flush);

int xfrm_policy_walk(struct net *net, struct xfrm_policy_walk *walk,
                     int (*func)(struct xfrm_policy *, int, int, void*),
                     void *data)
{
        struct xfrm_policy *pol;
        struct xfrm_policy_walk_entry *x;
        int error = 0;

        if (walk->type >= XFRM_POLICY_TYPE_MAX &&
            walk->type != XFRM_POLICY_TYPE_ANY)
                return -EINVAL;

        if (list_empty(&walk->walk.all) && walk->seq != 0)
                return 0;

        spin_lock_bh(&net->xfrm.xfrm_policy_lock);
        if (list_empty(&walk->walk.all))

                x = list_first_entry(&net->xfrm.policy_all, struct xfrm_policy_walk_entry, all);
        else
                x = list_first_entry(&walk->walk.all,
                                     struct xfrm_policy_walk_entry, all);

        list_for_each_entry_from(x, &net->xfrm.policy_all, all) {
                if (x->dead)
                        continue;
                pol = container_of(x, struct xfrm_policy, walk);
                if (walk->type != XFRM_POLICY_TYPE_ANY &&
                    walk->type != pol->type)
                        continue;
                error = func(pol, xfrm_policy_id2dir(pol->index),
                             walk->seq, data);
                if (error) {
                        list_move_tail(&walk->walk.all, &x->all);
                        goto out;
                }
                walk->seq++;
        }
        if (walk->seq == 0) {
                error = -ENOENT;
                goto out;
        }
        list_del_init(&walk->walk.all);
out:
        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
        return error;
}
EXPORT_SYMBOL(xfrm_policy_walk);

void xfrm_policy_walk_init(struct xfrm_policy_walk *walk, u8 type)
{
        INIT_LIST_HEAD(&walk->walk.all);
        walk->walk.dead = 1;
        walk->type = type;
        walk->seq = 0;
}
EXPORT_SYMBOL(xfrm_policy_walk_init);

void xfrm_policy_walk_done(struct xfrm_policy_walk *walk, struct net *net)
{
        if (list_empty(&walk->walk.all))
                return;

        spin_lock_bh(&net->xfrm.xfrm_policy_lock); /*FIXME where is net? */
        list_del(&walk->walk.all);
        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
}
EXPORT_SYMBOL(xfrm_policy_walk_done);

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

        if (pol->family != family ||
            (fl->flowi_mark & pol->mark.m) != pol->mark.v ||
            pol->type != type)
                return ret;

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

        return ret;
}

static struct xfrm_policy *xfrm_policy_lookup_bytype(struct net *net, u8 type,
                                                     const struct flowi *fl,
                                                     u16 family, u8 dir)
{
        int err;
        struct xfrm_policy *pol, *ret;
        const xfrm_address_t *daddr, *saddr;
        struct hlist_head *chain;
        unsigned int sequence;
        u32 priority;

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

        rcu_read_lock();
 retry:
        do {
                sequence = read_seqcount_begin(&xfrm_policy_hash_generation);
                chain = policy_hash_direct(net, daddr, saddr, family, dir);
        } while (read_seqcount_retry(&xfrm_policy_hash_generation, sequence));

        priority = ~0U;
        ret = NULL;
        hlist_for_each_entry_rcu(pol, 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 = &net->xfrm.policy_inexact[dir];
        hlist_for_each_entry_rcu(pol, chain, bydst) {
                if ((pol->priority >= priority) && ret)
                        break;

                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;
                        break;
                }
        }

        if (read_seqcount_retry(&xfrm_policy_hash_generation, sequence))
                goto retry;

        if (ret && !xfrm_pol_hold_rcu(ret))
                goto retry;
fail:
        rcu_read_unlock();

        return ret;
}

static struct xfrm_policy *
xfrm_policy_lookup(struct net *net, const struct flowi *fl, u16 family, u8 dir)
{
#ifdef CONFIG_XFRM_SUB_POLICY
        struct xfrm_policy *pol;

        pol = xfrm_policy_lookup_bytype(net, XFRM_POLICY_TYPE_SUB, fl, family, dir);
        if (pol != NULL)
                return pol;
#endif
        return xfrm_policy_lookup_bytype(net, XFRM_POLICY_TYPE_MAIN, fl, family, dir);
}

static struct xfrm_policy *xfrm_sk_policy_lookup(const struct sock *sk, int dir,
                                                 const struct flowi *fl, u16 family)
{
        struct xfrm_policy *pol;

        rcu_read_lock();
 again:
        pol = rcu_dereference(sk->sk_policy[dir]);
        if (pol != NULL) {
                bool match;
                int err = 0;

                if (pol->family != family) {
                        pol = NULL;
                        goto out;
                }

                match = xfrm_selector_match(&pol->selector, fl, family);
                if (match) {
                        if ((sk->sk_mark & pol->mark.m) != pol->mark.v) {
                                pol = NULL;
                                goto out;
                        }
                        err = security_xfrm_policy_lookup(pol->security,
                                                      fl->flowi_secid,
                                                      dir);
                        if (!err) {
                                if (!xfrm_pol_hold_rcu(pol))
                                        goto again;
                        } else if (err == -ESRCH) {
                                pol = NULL;
                        } else {
                                pol = ERR_PTR(err);
                        }
                } else
                        pol = NULL;
        }
out:
        rcu_read_unlock();
        return pol;
}

static void __xfrm_policy_link(struct xfrm_policy *pol, int dir)
{
        struct net *net = xp_net(pol);

        list_add(&pol->walk.all, &net->xfrm.policy_all);
        net->xfrm.policy_count[dir]++;
        xfrm_pol_hold(pol);
}

static struct xfrm_policy *__xfrm_policy_unlink(struct xfrm_policy *pol,
                                                int dir)
{
        struct net *net = xp_net(pol);

        if (list_empty(&pol->walk.all))
                return NULL;

        /* Socket policies are not hashed. */
        if (!hlist_unhashed(&pol->bydst)) {
                hlist_del_rcu(&pol->bydst);
                hlist_del(&pol->byidx);
        }

        list_del_init(&pol->walk.all);
        net->xfrm.policy_count[dir]--;

        return pol;
}

static void xfrm_sk_policy_link(struct xfrm_policy *pol, int dir)
{
        __xfrm_policy_link(pol, XFRM_POLICY_MAX + dir);
}

static void xfrm_sk_policy_unlink(struct xfrm_policy *pol, int dir)
{
        __xfrm_policy_unlink(pol, XFRM_POLICY_MAX + dir);
}

int xfrm_policy_delete(struct xfrm_policy *pol, int dir)
{
        struct net *net = xp_net(pol);

        spin_lock_bh(&net->xfrm.xfrm_policy_lock);
        pol = __xfrm_policy_unlink(pol, dir);
        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
        if (pol) {
                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 net *net = sock_net(sk);
        struct xfrm_policy *old_pol;

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

        spin_lock_bh(&net->xfrm.xfrm_policy_lock);
        old_pol = rcu_dereference_protected(sk->sk_policy[dir],
                                lockdep_is_held(&net->xfrm.xfrm_policy_lock));
        if (pol) {
                pol->curlft.add_time = get_seconds();
                pol->index = xfrm_gen_index(net, XFRM_POLICY_MAX+dir, 0);
                xfrm_sk_policy_link(pol, dir);
        }
        rcu_assign_pointer(sk->sk_policy[dir], pol);
        if (old_pol) {
                if (pol)
                        xfrm_policy_requeue(old_pol, pol);

                /* Unlinking succeeds always. This is the only function
                 * allowed to delete or replace socket policy.
                 */
                xfrm_sk_policy_unlink(old_pol, dir);
        }
        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);

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

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

        if (newp) {
                newp->selector = old->selector;
                if (security_xfrm_policy_clone(old->security,
                                               &newp->security)) {
                        kfree(newp);
                        return NULL;  /* ENOMEM */
                }
                newp->lft = old->lft;
                newp->curlft = old->curlft;
                newp->mark = old->mark;
                newp->action = old->action;
                newp->flags = old->flags;
                newp->xfrm_nr = old->xfrm_nr;
                newp->index = old->index;
                newp->type = old->type;
                newp->family = old->family;
                memcpy(newp->xfrm_vec, old->xfrm_vec,
                       newp->xfrm_nr*sizeof(struct xfrm_tmpl));
                spin_lock_bh(&net->xfrm.xfrm_policy_lock);
                xfrm_sk_policy_link(newp, dir);
                spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
                xfrm_pol_put(newp);
        }
        return newp;
}

int __xfrm_sk_clone_policy(struct sock *sk, const struct sock *osk)
{
        const struct xfrm_policy *p;
        struct xfrm_policy *np;
        int i, ret = 0;

        rcu_read_lock();
        for (i = 0; i < 2; i++) {
                p = rcu_dereference(osk->sk_policy[i]);
                if (p) {
                        np = clone_policy(p, i);
                        if (unlikely(!np)) {
                                ret = -ENOMEM;
                                break;
                        }
                        rcu_assign_pointer(sk->sk_policy[i], np);
                }
        }
        rcu_read_unlock();
        return ret;
}

static int
xfrm_get_saddr(struct net *net, int oif, xfrm_address_t *local,
               xfrm_address_t *remote, unsigned short family, u32 mark)
{
        int err;
        const struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);

        if (unlikely(afinfo == NULL))
                return -EINVAL;
        err = afinfo->get_saddr(net, oif, local, remote, mark);
        rcu_read_unlock();
        return err;
}

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

static int
xfrm_tmpl_resolve_one(struct xfrm_policy *policy, const struct flowi *fl,
                      struct xfrm_state **xfrm, unsigned short family)
{
        struct net *net = xp_net(policy);
        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 ||
                    tmpl->mode == XFRM_MODE_BEET) {
                        remote = &tmpl->id.daddr;
                        local = &tmpl->saddr;
                        if (xfrm_addr_any(local, tmpl->encap_family)) {
                                error = xfrm_get_saddr(net, fl->flowi_oif,
                                                       &tmp, remote,
                                                       tmpl->encap_family, 0);
                                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);
                } else if (error == -ESRCH) {
                        error = -EAGAIN;
                }

                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, const 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;

}

static int xfrm_get_tos(const struct flowi *fl, int family)
{
        const struct xfrm_policy_afinfo *afinfo;
        int tos;

        afinfo = xfrm_policy_get_afinfo(family);
        if (!afinfo)
                return 0;

        tos = afinfo->get_tos(fl);

        rcu_read_unlock();

        return tos;
}

static inline struct xfrm_dst *xfrm_alloc_dst(struct net *net, int family)
{
        const struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
        struct dst_ops *dst_ops;
        struct xfrm_dst *xdst;

        if (!afinfo)
                return ERR_PTR(-EINVAL);

        switch (family) {
        case AF_INET:
                dst_ops = &net->xfrm.xfrm4_dst_ops;
                break;
#if IS_ENABLED(CONFIG_IPV6)
        case AF_INET6:
                dst_ops = &net->xfrm.xfrm6_dst_ops;
                break;
#endif
        default:
                BUG();
        }
        xdst = dst_alloc(dst_ops, NULL, 1, DST_OBSOLETE_NONE, 0);

        if (likely(xdst)) {
                struct dst_entry *dst = &xdst->u.dst;

                memset(dst + 1, 0, sizeof(*xdst) - sizeof(*dst));
        } else
                xdst = ERR_PTR(-ENOBUFS);

        rcu_read_unlock();

        return xdst;
}

static inline int xfrm_init_path(struct xfrm_dst *path, struct dst_entry *dst,
                                 int nfheader_len)
{
        const struct xfrm_policy_afinfo *afinfo =
                xfrm_policy_get_afinfo(dst->ops->family);
        int err;

        if (!afinfo)
                return -EINVAL;

        err = afinfo->init_path(path, dst, nfheader_len);

        rcu_read_unlock();

        return err;
}

static inline int xfrm_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
                                const struct flowi *fl)
{
        const struct xfrm_policy_afinfo *afinfo =
                xfrm_policy_get_afinfo(xdst->u.dst.ops->family);
        int err;

        if (!afinfo)
                return -EINVAL;

        err = afinfo->fill_dst(xdst, dev, fl);

        rcu_read_unlock();

        return err;
}


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

static struct dst_entry *xfrm_bundle_create(struct xfrm_policy *policy,
                                            struct xfrm_state **xfrm,
                                            struct xfrm_dst **bundle,
                                            int nx,
                                            const struct flowi *fl,
                                            struct dst_entry *dst)
{
        struct net *net = xp_net(policy);
        unsigned long now = jiffies;
        struct net_device *dev;
        struct xfrm_mode *inner_mode;
        struct xfrm_dst *xdst_prev = NULL;
        struct xfrm_dst *xdst0 = NULL;
        int i = 0;
        int err;
        int header_len = 0;
        int nfheader_len = 0;
        int trailer_len = 0;
        int tos;
        int family = policy->selector.family;
        xfrm_address_t saddr, daddr;

        xfrm_flowi_addr_get(fl, &saddr, &daddr, family);

        tos = xfrm_get_tos(fl, family);

        dst_hold(dst);

        for (; i < nx; i++) {
                struct xfrm_dst *xdst = xfrm_alloc_dst(net, family);
                struct dst_entry *dst1 = &xdst->u.dst;

                err = PTR_ERR(xdst);
                if (IS_ERR(xdst)) {
                        dst_release(dst);
                        goto put_states;
                }

                bundle[i] = xdst;
                if (!xdst_prev)
                        xdst0 = xdst;
                else
                        /* Ref count is taken during xfrm_alloc_dst()
                         * No need to do dst_clone() on dst1
                         */
                        xfrm_dst_set_child(xdst_prev, &xdst->u.dst);

                if (xfrm[i]->sel.family == AF_UNSPEC) {
                        inner_mode = xfrm_ip2inner_mode(xfrm[i],
                                                        xfrm_af2proto(family));
                        if (!inner_mode) {
                                err = -EAFNOSUPPORT;
                                dst_release(dst);
                                goto put_states;
                        }
                } else
                        inner_mode = xfrm[i]->inner_mode;

                xdst->route = dst;
                dst_copy_metrics(dst1, dst);

                if (xfrm[i]->props.mode != XFRM_MODE_TRANSPORT) {
                        family = xfrm[i]->props.family;
                        dst = xfrm_dst_lookup(xfrm[i], tos, fl->flowi_oif,
                                              &saddr, &daddr, family,
                                              xfrm[i]->props.output_mark);
                        err = PTR_ERR(dst);
                        if (IS_ERR(dst))
                                goto put_states;
                } else
                        dst_hold(dst);

                dst1->xfrm = xfrm[i];
                xdst->xfrm_genid = xfrm[i]->genid;

                dst1->obsolete = DST_OBSOLETE_FORCE_CHK;
                dst1->flags |= DST_HOST;
                dst1->lastuse = now;

                dst1->input = dst_discard;
                dst1->output = inner_mode->afinfo->output;

                xdst_prev = xdst;

                header_len += xfrm[i]->props.header_len;
                if (xfrm[i]->type->flags & XFRM_TYPE_NON_FRAGMENT)
                        nfheader_len += xfrm[i]->props.header_len;
                trailer_len += xfrm[i]->props.trailer_len;
        }

        xfrm_dst_set_child(xdst_prev, dst);
        xdst0->path = dst;

        err = -ENODEV;
        dev = dst->dev;
        if (!dev)
                goto free_dst;

        xfrm_init_path(xdst0, dst, nfheader_len);
        xfrm_init_pmtu(bundle, nx);

        for (xdst_prev = xdst0; xdst_prev != (struct xfrm_dst *)dst;
             xdst_prev = (struct xfrm_dst *) xfrm_dst_child(&xdst_prev->u.dst)) {
                err = xfrm_fill_dst(xdst_prev, dev, fl);
                if (err)
                        goto free_dst;

                xdst_prev->u.dst.header_len = header_len;
                xdst_prev->u.dst.trailer_len = trailer_len;
                header_len -= xdst_prev->u.dst.xfrm->props.header_len;
                trailer_len -= xdst_prev->u.dst.xfrm->props.trailer_len;
        }

out:
        return &xdst0->u.dst;

put_states:
        for (; i < nx; i++)
                xfrm_state_put(xfrm[i]);
free_dst:
        if (xdst0)
                dst_release_immediate(&xdst0->u.dst);
        xdst0 = ERR_PTR(err);
        goto out;
}

static int xfrm_expand_policies(const struct flowi *fl, u16 family,
                                struct xfrm_policy **pols,
                                int *num_pols, int *num_xfrms)
{
        int i;

        if (*num_pols == 0 || !pols[0]) {
                *num_pols = 0;
                *num_xfrms = 0;
                return 0;
        }
        if (IS_ERR(pols[0]))
                return PTR_ERR(pols[0]);

        *num_xfrms = pols[0]->xfrm_nr;

#ifdef CONFIG_XFRM_SUB_POLICY
        if (pols[0] && pols[0]->action == XFRM_POLICY_ALLOW &&
            pols[0]->type != XFRM_POLICY_TYPE_MAIN) {
                pols[1] = xfrm_policy_lookup_bytype(xp_net(pols[0]),
                                                    XFRM_POLICY_TYPE_MAIN,
                                                    fl, family,
                                                    XFRM_POLICY_OUT);
                if (pols[1]) {
                        if (IS_ERR(pols[1])) {
                                xfrm_pols_put(pols, *num_pols);
                                return PTR_ERR(pols[1]);
                        }
                        (*num_pols)++;
                        (*num_xfrms) += pols[1]->xfrm_nr;
                }
        }
#endif
        for (i = 0; i < *num_pols; i++) {
                if (pols[i]->action != XFRM_POLICY_ALLOW) {
                        *num_xfrms = -1;
                        break;
                }
        }

        return 0;

}

static void xfrm_last_dst_update(struct xfrm_dst *xdst, struct xfrm_dst *old)
{
        this_cpu_write(xfrm_last_dst, xdst);
        if (old)
                dst_release(&old->u.dst);
}

static void __xfrm_pcpu_work_fn(void)
{
        struct xfrm_dst *old;

        old = this_cpu_read(xfrm_last_dst);
        if (old && !xfrm_bundle_ok(old))
                xfrm_last_dst_update(NULL, old);
}

static void xfrm_pcpu_work_fn(struct work_struct *work)
{
        local_bh_disable();
        rcu_read_lock();
        __xfrm_pcpu_work_fn();
        rcu_read_unlock();
        local_bh_enable();
}

void xfrm_policy_cache_flush(void)
{
        struct xfrm_dst *old;
        bool found = 0;
        int cpu;

        might_sleep();

        local_bh_disable();
        rcu_read_lock();
        for_each_possible_cpu(cpu) {
                old = per_cpu(xfrm_last_dst, cpu);
                if (old && !xfrm_bundle_ok(old)) {
                        if (smp_processor_id() == cpu) {
                                __xfrm_pcpu_work_fn();
                                continue;
                        }
                        found = true;
                        break;
                }
        }

        rcu_read_unlock();
        local_bh_enable();

        if (!found)
                return;

        get_online_cpus();

        for_each_possible_cpu(cpu) {
                bool bundle_release;

                rcu_read_lock();
                old = per_cpu(xfrm_last_dst, cpu);
                bundle_release = old && !xfrm_bundle_ok(old);
                rcu_read_unlock();

                if (!bundle_release)
                        continue;

                if (cpu_online(cpu)) {
                        schedule_work_on(cpu, &xfrm_pcpu_work[cpu]);
                        continue;
                }

                rcu_read_lock();
                old = per_cpu(xfrm_last_dst, cpu);
                if (old && !xfrm_bundle_ok(old)) {
                        per_cpu(xfrm_last_dst, cpu) = NULL;
                        dst_release(&old->u.dst);
                }
                rcu_read_unlock();
        }

        put_online_cpus();
}

static bool xfrm_xdst_can_reuse(struct xfrm_dst *xdst,
                                struct xfrm_state * const xfrm[],
                                int num)
{
        const struct dst_entry *dst = &xdst->u.dst;
        int i;

        if (xdst->num_xfrms != num)
                return false;

        for (i = 0; i < num; i++) {
                if (!dst || dst->xfrm != xfrm[i])
                        return false;
                dst = xfrm_dst_child(dst);
        }

        return xfrm_bundle_ok(xdst);
}

static struct xfrm_dst *
xfrm_resolve_and_create_bundle(struct xfrm_policy **pols, int num_pols,
                               const struct flowi *fl, u16 family,
                               struct dst_entry *dst_orig)
{
        struct net *net = xp_net(pols[0]);
        struct xfrm_state *xfrm[XFRM_MAX_DEPTH];
        struct xfrm_dst *bundle[XFRM_MAX_DEPTH];
        struct xfrm_dst *xdst, *old;
        struct dst_entry *dst;
        int err;

        /* Try to instantiate a bundle */
        err = xfrm_tmpl_resolve(pols, num_pols, fl, xfrm, family);
        if (err <= 0) {
                if (err != 0 && err != -EAGAIN)
                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTPOLERROR);
                return ERR_PTR(err);
        }

        xdst = this_cpu_read(xfrm_last_dst);
        if (xdst &&
            xdst->u.dst.dev == dst_orig->dev &&
            xdst->num_pols == num_pols &&
            memcmp(xdst->pols, pols,
                   sizeof(struct xfrm_policy *) * num_pols) == 0 &&
            xfrm_xdst_can_reuse(xdst, xfrm, err)) {
                dst_hold(&xdst->u.dst);
                xfrm_pols_put(pols, num_pols);
                while (err > 0)
                        xfrm_state_put(xfrm[--err]);
                return xdst;
        }

        old = xdst;

        dst = xfrm_bundle_create(pols[0], xfrm, bundle, err, fl, dst_orig);
        if (IS_ERR(dst)) {
                XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTBUNDLEGENERROR);
                return ERR_CAST(dst);
        }

        xdst = (struct xfrm_dst *)dst;
        xdst->num_xfrms = err;
        xdst->num_pols = num_pols;
        memcpy(xdst->pols, pols, sizeof(struct xfrm_policy *) * num_pols);
        xdst->policy_genid = atomic_read(&pols[0]->genid);

        atomic_set(&xdst->u.dst.__refcnt, 2);
        xfrm_last_dst_update(xdst, old);

        return xdst;
}

static void xfrm_policy_queue_process(struct timer_list *t)
{
        struct sk_buff *skb;
        struct sock *sk;
        struct dst_entry *dst;
        struct xfrm_policy *pol = from_timer(pol, t, polq.hold_timer);
        struct net *net = xp_net(pol);
        struct xfrm_policy_queue *pq = &pol->polq;
        struct flowi fl;
        struct sk_buff_head list;

        spin_lock(&pq->hold_queue.lock);
        skb = skb_peek(&pq->hold_queue);
        if (!skb) {
                spin_unlock(&pq->hold_queue.lock);
                goto out;
        }
        dst = skb_dst(skb);
        sk = skb->sk;
        xfrm_decode_session(skb, &fl, dst->ops->family);
        spin_unlock(&pq->hold_queue.lock);

        dst_hold(xfrm_dst_path(dst));
        dst = xfrm_lookup(net, xfrm_dst_path(dst), &fl, sk, XFRM_LOOKUP_QUEUE);
        if (IS_ERR(dst))
                goto purge_queue;

        if (dst->flags & DST_XFRM_QUEUE) {
                dst_release(dst);

                if (pq->timeout >= XFRM_QUEUE_TMO_MAX)
                        goto purge_queue;

                pq->timeout = pq->timeout << 1;
                if (!mod_timer(&pq->hold_timer, jiffies + pq->timeout))
                        xfrm_pol_hold(pol);
        goto out;
        }

        dst_release(dst);

        __skb_queue_head_init(&list);

        spin_lock(&pq->hold_queue.lock);
        pq->timeout = 0;
        skb_queue_splice_init(&pq->hold_queue, &list);
        spin_unlock(&pq->hold_queue.lock);

        while (!skb_queue_empty(&list)) {
                skb = __skb_dequeue(&list);

                xfrm_decode_session(skb, &fl, skb_dst(skb)->ops->family);
                dst_hold(xfrm_dst_path(skb_dst(skb)));
                dst = xfrm_lookup(net, xfrm_dst_path(skb_dst(skb)), &fl, skb->sk, 0);
                if (IS_ERR(dst)) {
                        kfree_skb(skb);
                        continue;
                }

                nf_reset(skb);
                skb_dst_drop(skb);
                skb_dst_set(skb, dst);

                dst_output(net, skb->sk, skb);
        }

out:
        xfrm_pol_put(pol);
        return;

purge_queue:
        pq->timeout = 0;
        skb_queue_purge(&pq->hold_queue);
        xfrm_pol_put(pol);
}

static int xdst_queue_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
        unsigned long sched_next;
        struct dst_entry *dst = skb_dst(skb);
        struct xfrm_dst *xdst = (struct xfrm_dst *) dst;
        struct xfrm_policy *pol = xdst->pols[0];
        struct xfrm_policy_queue *pq = &pol->polq;

        if (unlikely(skb_fclone_busy(sk, skb))) {
                kfree_skb(skb);
                return 0;
        }

        if (pq->hold_queue.qlen > XFRM_MAX_QUEUE_LEN) {
                kfree_skb(skb);
                return -EAGAIN;
        }

        skb_dst_force(skb);

        spin_lock_bh(&pq->hold_queue.lock);

        if (!pq->timeout)
                pq->timeout = XFRM_QUEUE_TMO_MIN;

        sched_next = jiffies + pq->timeout;

        if (del_timer(&pq->hold_timer)) {
                if (time_before(pq->hold_timer.expires, sched_next))
                        sched_next = pq->hold_timer.expires;
                xfrm_pol_put(pol);
        }

        __skb_queue_tail(&pq->hold_queue, skb);
        if (!mod_timer(&pq->hold_timer, sched_next))
                xfrm_pol_hold(pol);

        spin_unlock_bh(&pq->hold_queue.lock);

        return 0;
}

static struct xfrm_dst *xfrm_create_dummy_bundle(struct net *net,
                                                 struct xfrm_flo *xflo,
                                                 const struct flowi *fl,
                                                 int num_xfrms,
                                                 u16 family)
{
        int err;
        struct net_device *dev;
        struct dst_entry *dst;

        struct dst_entry *dst1;
        struct xfrm_dst *xdst;

        xdst = xfrm_alloc_dst(net, family);
        if (IS_ERR(xdst))
                return xdst;

        if (!(xflo->flags & XFRM_LOOKUP_QUEUE) ||
            net->xfrm.sysctl_larval_drop ||
            num_xfrms <= 0)
                return xdst;

        dst = xflo->dst_orig;
        dst1 = &xdst->u.dst;
        dst_hold(dst);
        xdst->route = dst;

        dst_copy_metrics(dst1, dst);

        dst1->obsolete = DST_OBSOLETE_FORCE_CHK;
        dst1->flags |= DST_HOST | DST_XFRM_QUEUE;
        dst1->lastuse = jiffies;

        dst1->input = dst_discard;
        dst1->output = xdst_queue_output;

        dst_hold(dst);
        xfrm_dst_set_child(xdst, dst);
        xdst->path = dst;

        xfrm_init_path((struct xfrm_dst *)dst1, dst, 0);

        err = -ENODEV;
        dev = dst->dev;
        if (!dev)
                goto free_dst;

        err = xfrm_fill_dst(xdst, dev, fl);
        if (err)
                goto free_dst;

out:
        return xdst;

free_dst:
        dst_release(dst1);
        xdst = ERR_PTR(err);
        goto out;
}

static struct xfrm_dst *
xfrm_bundle_lookup(struct net *net, const struct flowi *fl, u16 family, u8 dir, struct xfrm_flo *xflo)
{
        struct xfrm_policy *pols[XFRM_POLICY_TYPE_MAX];
        int num_pols = 0, num_xfrms = 0, err;
        struct xfrm_dst *xdst;

        /* Resolve policies to use if we couldn't get them from
         * previous cache entry */
        num_pols = 1;
        pols[0] = xfrm_policy_lookup(net, fl, family, dir);
        err = xfrm_expand_policies(fl, family, pols,
                                           &num_pols, &num_xfrms);
        if (err < 0)
                goto inc_error;
        if (num_pols == 0)
                return NULL;
        if (num_xfrms <= 0)
                goto make_dummy_bundle;

        local_bh_disable();
        xdst = xfrm_resolve_and_create_bundle(pols, num_pols, fl, family,
                                              xflo->dst_orig);
        local_bh_enable();

        if (IS_ERR(xdst)) {
                err = PTR_ERR(xdst);
                if (err != -EAGAIN)
                        goto error;
                goto make_dummy_bundle;
        } else if (xdst == NULL) {
                num_xfrms = 0;
                goto make_dummy_bundle;
        }

        return xdst;

make_dummy_bundle:
        /* We found policies, but there's no bundles to instantiate:
         * either because the policy blocks, has no transformations or
         * we could not build template (no xfrm_states).*/
        xdst = xfrm_create_dummy_bundle(net, xflo, fl, num_xfrms, family);
        if (IS_ERR(xdst)) {
                xfrm_pols_put(pols, num_pols);
                return ERR_CAST(xdst);
        }
        xdst->num_pols = num_pols;
        xdst->num_xfrms = num_xfrms;
        memcpy(xdst->pols, pols, sizeof(struct xfrm_policy *) * num_pols);

        return xdst;

inc_error:
        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTPOLERROR);
error:
        xfrm_pols_put(pols, num_pols);
        return ERR_PTR(err);
}

static struct dst_entry *make_blackhole(struct net *net, u16 family,
                                        struct dst_entry *dst_orig)
{
        const struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
        struct dst_entry *ret;

        if (!afinfo) {
                dst_release(dst_orig);
                return ERR_PTR(-EINVAL);
        } else {
                ret = afinfo->blackhole_route(net, dst_orig);
        }
        rcu_read_unlock();

        return ret;
}

/* 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.
 */
struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
                              const struct flowi *fl,
                              const struct sock *sk, int flags)
{
        struct xfrm_policy *pols[XFRM_POLICY_TYPE_MAX];
        struct xfrm_dst *xdst;
        struct dst_entry *dst, *route;
        u16 family = dst_orig->ops->family;
        u8 dir = XFRM_POLICY_OUT;
        int i, err, num_pols, num_xfrms = 0, drop_pols = 0;

        dst = NULL;
        xdst = NULL;
        route = NULL;

        sk = sk_const_to_full_sk(sk);
        if (sk && sk->sk_policy[XFRM_POLICY_OUT]) {
                num_pols = 1;
                pols[0] = xfrm_sk_policy_lookup(sk, XFRM_POLICY_OUT, fl, family);
                err = xfrm_expand_policies(fl, family, pols,
                                           &num_pols, &num_xfrms);
                if (err < 0)
                        goto dropdst;

                if (num_pols) {
                        if (num_xfrms <= 0) {
                                drop_pols = num_pols;
                                goto no_transform;
                        }

                        local_bh_disable();
                        xdst = xfrm_resolve_and_create_bundle(
                                        pols, num_pols, fl,
                                        family, dst_orig);
                        local_bh_enable();

                        if (IS_ERR(xdst)) {
                                xfrm_pols_put(pols, num_pols);
                                err = PTR_ERR(xdst);
                                goto dropdst;
                        } else if (xdst == NULL) {
                                num_xfrms = 0;
                                drop_pols = num_pols;
                                goto no_transform;
                        }

                        route = xdst->route;
                }
        }

        if (xdst == NULL) {
                struct xfrm_flo xflo;

                xflo.dst_orig = dst_orig;
                xflo.flags = flags;

                /* To accelerate a bit...  */
                if ((dst_orig->flags & DST_NOXFRM) ||
                    !net->xfrm.policy_count[XFRM_POLICY_OUT])
                        goto nopol;

                xdst = xfrm_bundle_lookup(net, fl, family, dir, &xflo);
                if (xdst == NULL)
                        goto nopol;
                if (IS_ERR(xdst)) {
                        err = PTR_ERR(xdst);
                        goto dropdst;
                }

                num_pols = xdst->num_pols;
                num_xfrms = xdst->num_xfrms;
                memcpy(pols, xdst->pols, sizeof(struct xfrm_policy *) * num_pols);
                route = xdst->route;
        }

        dst = &xdst->u.dst;
        if (route == NULL && num_xfrms > 0) {
                /* The only case when xfrm_bundle_lookup() returns a
                 * bundle with null route, is when the template could
                 * not be resolved. It means policies are there, but
                 * bundle could not be created, since we don't yet
                 * have the xfrm_state's. We need to wait for KM to
                 * negotiate new SA's or bail out with error.*/
                if (net->xfrm.sysctl_larval_drop) {
                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTNOSTATES);
                        err = -EREMOTE;
                        goto error;
                }

                err = -EAGAIN;

                XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTNOSTATES);
                goto error;
        }

no_transform:
        if (num_pols == 0)
                goto nopol;

        if ((flags & XFRM_LOOKUP_ICMP) &&
            !(pols[0]->flags & XFRM_POLICY_ICMP)) {
                err = -ENOENT;
                goto error;
        }

        for (i = 0; i < num_pols; i++)
                pols[i]->curlft.use_time = get_seconds();

        if (num_xfrms < 0) {
                /* Prohibit the flow */
                XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTPOLBLOCK);
                err = -EPERM;
                goto error;
        } else if (num_xfrms > 0) {
                /* Flow transformed */
                dst_release(dst_orig);
        } else {
                /* Flow passes untransformed */
                dst_release(dst);
                dst = dst_orig;
        }
ok:
        xfrm_pols_put(pols, drop_pols);
        if (dst && dst->xfrm &&
            dst->xfrm->props.mode == XFRM_MODE_TUNNEL)
                dst->flags |= DST_XFRM_TUNNEL;
        return dst;

nopol:
        if (!(flags & XFRM_LOOKUP_ICMP)) {
                dst = dst_orig;
                goto ok;
        }
        err = -ENOENT;
error:
        dst_release(dst);
dropdst:
        if (!(flags & XFRM_LOOKUP_KEEP_DST_REF))
                dst_release(dst_orig);
        xfrm_pols_put(pols, drop_pols);
        return ERR_PTR(err);
}
EXPORT_SYMBOL(xfrm_lookup);

/* Callers of xfrm_lookup_route() must ensure a call to dst_output().
 * Otherwise we may send out blackholed packets.
 */
struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
                                    const struct flowi *fl,
                                    const struct sock *sk, int flags)
{
        struct dst_entry *dst = xfrm_lookup(net, dst_orig, fl, sk,
                                            flags | XFRM_LOOKUP_QUEUE |
                                            XFRM_LOOKUP_KEEP_DST_REF);

        if (IS_ERR(dst) && PTR_ERR(dst) == -EREMOTE)
                return make_blackhole(net, dst_orig->ops->family, dst_orig);

        return dst;
}
EXPORT_SYMBOL(xfrm_lookup_route);

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

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

/* 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(const struct xfrm_tmpl *tmpl, const struct xfrm_state *x,
              unsigned short family)
{
        if (xfrm_state_kern(x))
                return tmpl->optional && !xfrm_state_addr_cmp(tmpl, x, tmpl->encap_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->allalgs || (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(const struct xfrm_tmpl *tmpl, const 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 int family, int reverse)
{
        const struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
        int err;

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

        afinfo->decode_session(skb, fl, reverse);
        err = security_xfrm_decode_session(skb, &fl->flowi_secid);
        rcu_read_unlock();
        return err;
}
EXPORT_SYMBOL(__xfrm_decode_session);

static inline int secpath_has_nontransport(const 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 net *net = dev_net(skb->dev);
        struct xfrm_policy *pol;
        struct xfrm_policy *pols[XFRM_POLICY_TYPE_MAX];
        int npols = 0;
        int xfrm_nr;
        int pi;
        int reverse;
        struct flowi fl;
        int xerr_idx = -1;

        reverse = dir & ~XFRM_POLICY_MASK;
        dir &= XFRM_POLICY_MASK;

        if (__xfrm_decode_session(skb, &fl, family, reverse) < 0) {
                XFRM_INC_STATS(net, LINUX_MIB_XFRMINHDRERROR);
                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)) {
                                XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEMISMATCH);
                                return 0;
                        }
                }
        }

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

        if (!pol)
                pol = xfrm_policy_lookup(net, &fl, family, dir);

        if (IS_ERR(pol)) {
                XFRM_INC_STATS(net, LINUX_MIB_XFRMINPOLERROR);
                return 0;
        }

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

        pol->curlft.use_time = get_seconds();

        pols[0] = pol;
        npols++;
#ifdef CONFIG_XFRM_SUB_POLICY
        if (pols[0]->type != XFRM_POLICY_TYPE_MAIN) {
                pols[1] = xfrm_policy_lookup_bytype(net, XFRM_POLICY_TYPE_MAIN,
                                                    &fl, family,
                                                    XFRM_POLICY_IN);
                if (pols[1]) {
                        if (IS_ERR(pols[1])) {
                                XFRM_INC_STATS(net, LINUX_MIB_XFRMINPOLERROR);
                                return 0;
                        }
                        pols[1]->curlft.use_time = get_seconds();
                        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) {
                                XFRM_INC_STATS(net, LINUX_MIB_XFRMINPOLBLOCK);
                                goto reject;
                        }
                        if (ti + pols[pi]->xfrm_nr >= XFRM_MAX_DEPTH) {
                                XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
                                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, net);
                        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);
                                XFRM_INC_STATS(net, LINUX_MIB_XFRMINTMPLMISMATCH);
                                goto reject;
                        }
                }

                if (secpath_has_nontransport(sp, k, &xerr_idx)) {
                        XFRM_INC_STATS(net, LINUX_MIB_XFRMINTMPLMISMATCH);
                        goto reject;
                }

                xfrm_pols_put(pols, npols);
                return 1;
        }
        XFRM_INC_STATS(net, LINUX_MIB_XFRMINPOLBLOCK);

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 net *net = dev_net(skb->dev);
        struct flowi fl;
        struct dst_entry *dst;
        int res = 1;

        if (xfrm_decode_session(skb, &fl, family) < 0) {
                XFRM_INC_STATS(net, LINUX_MIB_XFRMFWDHDRERROR);
                return 0;
        }

        skb_dst_force(skb);

        dst = xfrm_lookup(net, skb_dst(skb), &fl, NULL, XFRM_LOOKUP_QUEUE);
        if (IS_ERR(dst)) {
                res = 0;
                dst = NULL;
        }
        skb_dst_set(skb, dst);
        return res;
}
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 DST_OBSOLETE_FORCE_CHK 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 dst is removed from the fib tree, DST_OBSOLETE_DEAD will
         * be marked on it.
         * This will force stale_bundle() to fail on any xdst bundle with
         * this dst linked in it.
         */
        if (dst->obsolete < 0 && !stale_bundle(dst))
                return dst;

        return NULL;
}

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

void xfrm_dst_ifdown(struct dst_entry *dst, struct net_device *dev)
{
        while ((dst = xfrm_dst_child(dst)) && dst->xfrm && dst->dev == dev) {
                dst->dev = dev_net(dev)->loopback_dev;
                dev_hold(dst->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. */
}

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 xfrm_init_pmtu(struct xfrm_dst **bundle, int nr)
{
        while (nr--) {
                struct xfrm_dst *xdst = bundle[nr];
                u32 pmtu, route_mtu_cached;
                struct dst_entry *dst;

                dst = &xdst->u.dst;
                pmtu = dst_mtu(xfrm_dst_child(dst));
                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_metric_set(dst, RTAX_MTU, pmtu);
        }
}

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

static int xfrm_bundle_ok(struct xfrm_dst *first)
{
        struct xfrm_dst *bundle[XFRM_MAX_DEPTH];
        struct dst_entry *dst = &first->u.dst;
        struct xfrm_dst *xdst;
        int start_from, nr;
        u32 mtu;

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

        if (dst->flags & DST_XFRM_QUEUE)
                return 1;

        start_from = nr = 0;
        do {
                struct xfrm_dst *xdst = (struct xfrm_dst *)dst;

                if (dst->xfrm->km.state != XFRM_STATE_VALID)
                        return 0;
                if (xdst->xfrm_genid != dst->xfrm->genid)
                        return 0;
                if (xdst->num_pols > 0 &&
                    xdst->policy_genid != atomic_read(&xdst->pols[0]->genid))
                        return 0;

                bundle[nr++] = xdst;

                mtu = dst_mtu(xfrm_dst_child(dst));
                if (xdst->child_mtu_cached != mtu) {
                        start_from = nr;
                        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) {
                        start_from = nr;
                        xdst->route_mtu_cached = mtu;
                }

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

        if (likely(!start_from))
                return 1;

        xdst = bundle[start_from - 1];
        mtu = xdst->child_mtu_cached;
        while (start_from--) {
                dst = &xdst->u.dst;

                mtu = xfrm_state_mtu(dst->xfrm, mtu);
                if (mtu > xdst->route_mtu_cached)
                        mtu = xdst->route_mtu_cached;
                dst_metric_set(dst, RTAX_MTU, mtu);
                if (!start_from)
                        break;

                xdst = bundle[start_from - 1];
                xdst->child_mtu_cached = mtu;
        }

        return 1;
}

static unsigned int xfrm_default_advmss(const struct dst_entry *dst)
{
        return dst_metric_advmss(xfrm_dst_path(dst));
}

static unsigned int xfrm_mtu(const struct dst_entry *dst)
{
        unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);

        return mtu ? : dst_mtu(xfrm_dst_path(dst));
}

static const void *xfrm_get_dst_nexthop(const struct dst_entry *dst,
                                        const void *daddr)
{
        while (dst->xfrm) {
                const struct xfrm_state *xfrm = dst->xfrm;

                dst = xfrm_dst_child(dst);

                if (xfrm->props.mode == XFRM_MODE_TRANSPORT)
                        continue;
                if (xfrm->type->flags & XFRM_TYPE_REMOTE_COADDR)
                        daddr = xfrm->coaddr;
                else if (!(xfrm->type->flags & XFRM_TYPE_LOCAL_COADDR))
                        daddr = &xfrm->id.daddr;
        }
        return daddr;
}

static struct neighbour *xfrm_neigh_lookup(const struct dst_entry *dst,
                                           struct sk_buff *skb,
                                           const void *daddr)
{
        const struct dst_entry *path = xfrm_dst_path(dst);

        if (!skb)
                daddr = xfrm_get_dst_nexthop(dst, daddr);
        return path->ops->neigh_lookup(path, skb, daddr);
}

static void xfrm_confirm_neigh(const struct dst_entry *dst, const void *daddr)
{
        const struct dst_entry *path = xfrm_dst_path(dst);

        daddr = xfrm_get_dst_nexthop(dst, daddr);
        path->ops->confirm_neigh(path, daddr);
}

int xfrm_policy_register_afinfo(const struct xfrm_policy_afinfo *afinfo, int family)
{
        int err = 0;

        if (WARN_ON(family >= ARRAY_SIZE(xfrm_policy_afinfo)))
                return -EAFNOSUPPORT;

        spin_lock(&xfrm_policy_afinfo_lock);
        if (unlikely(xfrm_policy_afinfo[family] != NULL))
                err = -EEXIST;
        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->default_advmss == NULL))
                        dst_ops->default_advmss = xfrm_default_advmss;
                if (likely(dst_ops->mtu == NULL))
                        dst_ops->mtu = xfrm_mtu;
                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(dst_ops->neigh_lookup == NULL))
                        dst_ops->neigh_lookup = xfrm_neigh_lookup;
                if (likely(!dst_ops->confirm_neigh))
                        dst_ops->confirm_neigh = xfrm_confirm_neigh;
                rcu_assign_pointer(xfrm_policy_afinfo[family], afinfo);
        }
        spin_unlock(&xfrm_policy_afinfo_lock);

        return err;
}
EXPORT_SYMBOL(xfrm_policy_register_afinfo);

void xfrm_policy_unregister_afinfo(const struct xfrm_policy_afinfo *afinfo)
{
        struct dst_ops *dst_ops = afinfo->dst_ops;
        int i;

        for (i = 0; i < ARRAY_SIZE(xfrm_policy_afinfo); i++) {
                if (xfrm_policy_afinfo[i] != afinfo)
                        continue;
                RCU_INIT_POINTER(xfrm_policy_afinfo[i], NULL);
                break;
        }

        synchronize_rcu();

        dst_ops->kmem_cachep = NULL;
        dst_ops->check = NULL;
        dst_ops->negative_advice = NULL;
        dst_ops->link_failure = NULL;
}
EXPORT_SYMBOL(xfrm_policy_unregister_afinfo);

#ifdef CONFIG_XFRM_STATISTICS
static int __net_init xfrm_statistics_init(struct net *net)
{
        int rv;
        net->mib.xfrm_statistics = alloc_percpu(struct linux_xfrm_mib);
        if (!net->mib.xfrm_statistics)
                return -ENOMEM;
        rv = xfrm_proc_init(net);
        if (rv < 0)
                free_percpu(net->mib.xfrm_statistics);
        return rv;
}

static void xfrm_statistics_fini(struct net *net)
{
        xfrm_proc_fini(net);
        free_percpu(net->mib.xfrm_statistics);
}
#else
static int __net_init xfrm_statistics_init(struct net *net)
{
        return 0;
}

static void xfrm_statistics_fini(struct net *net)
{
}
#endif

static int __net_init xfrm_policy_init(struct net *net)
{
        unsigned int hmask, sz;
        int dir;

        if (net_eq(net, &init_net))
                xfrm_dst_cache = kmem_cache_create("xfrm_dst_cache",
                                           sizeof(struct xfrm_dst),
                                           0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
                                           NULL);

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

        net->xfrm.policy_byidx = xfrm_hash_alloc(sz);
        if (!net->xfrm.policy_byidx)
                goto out_byidx;
        net->xfrm.policy_idx_hmask = hmask;

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

                net->xfrm.policy_count[dir] = 0;
                net->xfrm.policy_count[XFRM_POLICY_MAX + dir] = 0;
                INIT_HLIST_HEAD(&net->xfrm.policy_inexact[dir]);

                htab = &net->xfrm.policy_bydst[dir];
                htab->table = xfrm_hash_alloc(sz);
                if (!htab->table)
                        goto out_bydst;
                htab->hmask = hmask;
                htab->dbits4 = 32;
                htab->sbits4 = 32;
                htab->dbits6 = 128;
                htab->sbits6 = 128;
        }
        net->xfrm.policy_hthresh.lbits4 = 32;
        net->xfrm.policy_hthresh.rbits4 = 32;
        net->xfrm.policy_hthresh.lbits6 = 128;
        net->xfrm.policy_hthresh.rbits6 = 128;

        seqlock_init(&net->xfrm.policy_hthresh.lock);

        INIT_LIST_HEAD(&net->xfrm.policy_all);
        INIT_WORK(&net->xfrm.policy_hash_work, xfrm_hash_resize);
        INIT_WORK(&net->xfrm.policy_hthresh.work, xfrm_hash_rebuild);
        if (net_eq(net, &init_net))
                xfrm_dev_init();
        return 0;

out_bydst:
        for (dir--; dir >= 0; dir--) {
                struct xfrm_policy_hash *htab;

                htab = &net->xfrm.policy_bydst[dir];
                xfrm_hash_free(htab->table, sz);
        }
        xfrm_hash_free(net->xfrm.policy_byidx, sz);
out_byidx:
        return -ENOMEM;
}

static void xfrm_policy_fini(struct net *net)
{
        unsigned int sz;
        int dir;

        flush_work(&net->xfrm.policy_hash_work);
#ifdef CONFIG_XFRM_SUB_POLICY
        xfrm_policy_flush(net, XFRM_POLICY_TYPE_SUB, false);
#endif
        xfrm_policy_flush(net, XFRM_POLICY_TYPE_MAIN, false);

        WARN_ON(!list_empty(&net->xfrm.policy_all));

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

                WARN_ON(!hlist_empty(&net->xfrm.policy_inexact[dir]));

                htab = &net->xfrm.policy_bydst[dir];
                sz = (htab->hmask + 1) * sizeof(struct hlist_head);
                WARN_ON(!hlist_empty(htab->table));
                xfrm_hash_free(htab->table, sz);
        }

        sz = (net->xfrm.policy_idx_hmask + 1) * sizeof(struct hlist_head);
        WARN_ON(!hlist_empty(net->xfrm.policy_byidx));
        xfrm_hash_free(net->xfrm.policy_byidx, sz);
}

static int __net_init xfrm_net_init(struct net *net)
{
        int rv;

        /* Initialize the per-net locks here */
        spin_lock_init(&net->xfrm.xfrm_state_lock);
        spin_lock_init(&net->xfrm.xfrm_policy_lock);
        mutex_init(&net->xfrm.xfrm_cfg_mutex);

        rv = xfrm_statistics_init(net);
        if (rv < 0)
                goto out_statistics;
        rv = xfrm_state_init(net);
        if (rv < 0)
                goto out_state;
        rv = xfrm_policy_init(net);
        if (rv < 0)
                goto out_policy;
        rv = xfrm_sysctl_init(net);
        if (rv < 0)
                goto out_sysctl;

        return 0;

out_sysctl:
        xfrm_policy_fini(net);
out_policy:
        xfrm_state_fini(net);
out_state:
        xfrm_statistics_fini(net);
out_statistics:
        return rv;
}

static void __net_exit xfrm_net_exit(struct net *net)
{
        xfrm_sysctl_fini(net);
        xfrm_policy_fini(net);
        xfrm_state_fini(net);
        xfrm_statistics_fini(net);
}

static struct pernet_operations __net_initdata xfrm_net_ops = {
        .init = xfrm_net_init,
        .exit = xfrm_net_exit,
};

void __init xfrm_init(void)
{
        int i;

        xfrm_pcpu_work = kmalloc_array(NR_CPUS, sizeof(*xfrm_pcpu_work),
                                       GFP_KERNEL);
        BUG_ON(!xfrm_pcpu_work);

        for (i = 0; i < NR_CPUS; i++)
                INIT_WORK(&xfrm_pcpu_work[i], xfrm_pcpu_work_fn);