// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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 <linux/rhashtable.h>
#include <linux/if_tunnel.h>
#include <net/dst.h>
#include <net/flow.h>
#include <net/xfrm.h>
#include <net/ip.h>
#if IS_ENABLED(CONFIG_IPV6_MIP6)
#include <net/mip6.h>
#endif
#ifdef CONFIG_XFRM_STATISTICS
#include <net/snmp.h>
#endif
#ifdef CONFIG_XFRM_ESPINTCP
#include <net/espintcp.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;
};

/* prefixes smaller than this are stored in lists, not trees. */
#define INEXACT_PREFIXLEN_IPV4  16
#define INEXACT_PREFIXLEN_IPV6  48

struct xfrm_pol_inexact_node {
        struct rb_node node;
        union {
                xfrm_address_t addr;
                struct rcu_head rcu;
        };
        u8 prefixlen;

        struct rb_root root;

        /* the policies matching this node, can be empty list */
        struct hlist_head hhead;
};

/* xfrm inexact policy search tree:
 * xfrm_pol_inexact_bin = hash(dir,type,family,if_id);
 *  |
 * +---- root_d: sorted by daddr:prefix
 * |                 |
 * |        xfrm_pol_inexact_node
 * |                 |
 * |                 +- root: sorted by saddr/prefix
 * |                 |              |
 * |                 |         xfrm_pol_inexact_node
 * |                 |              |
 * |                 |              + root: unused
 * |                 |              |
 * |                 |              + hhead: saddr:daddr policies
 * |                 |
 * |                 +- coarse policies and all any:daddr policies
 * |
 * +---- root_s: sorted by saddr:prefix
 * |                 |
 * |        xfrm_pol_inexact_node
 * |                 |
 * |                 + root: unused
 * |                 |
 * |                 + hhead: saddr:any policies
 * |
 * +---- coarse policies and all any:any policies
 *
 * Lookups return four candidate lists:
 * 1. any:any list from top-level xfrm_pol_inexact_bin
 * 2. any:daddr list from daddr tree
 * 3. saddr:daddr list from 2nd level daddr tree
 * 4. saddr:any list from saddr tree
 *
 * This result set then needs to be searched for the policy with
 * the lowest priority.  If two results have same prio, youngest one wins.
 */

struct xfrm_pol_inexact_key {
        possible_net_t net;
        u32 if_id;
        u16 family;
        u8 dir, type;
};

struct xfrm_pol_inexact_bin {
        struct xfrm_pol_inexact_key k;
        struct rhash_head head;
        /* list containing '*:*' policies */
        struct hlist_head hhead;

        seqcount_spinlock_t count;
        /* tree sorted by daddr/prefix */
        struct rb_root root_d;

        /* tree sorted by saddr/prefix */
        struct rb_root root_s;

        /* slow path below */
        struct list_head inexact_bins;
        struct rcu_head rcu;
};

enum xfrm_pol_inexact_candidate_type {
        XFRM_POL_CAND_BOTH,
        XFRM_POL_CAND_SADDR,
        XFRM_POL_CAND_DADDR,
        XFRM_POL_CAND_ANY,

        XFRM_POL_CAND_MAX,
};

struct xfrm_pol_inexact_candidates {
        struct hlist_head *res[XFRM_POL_CAND_MAX];
};

static DEFINE_SPINLOCK(xfrm_if_cb_lock);
static struct xfrm_if_cb const __rcu *xfrm_if_cb __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 __ro_after_init;

static struct rhashtable xfrm_policy_inexact_table;
static const struct rhashtable_params xfrm_pol_inexact_params;

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 struct xfrm_pol_inexact_bin *
xfrm_policy_inexact_lookup(struct net *net, u8 type, u16 family, u8 dir,
                           u32 if_id);

static struct xfrm_pol_inexact_bin *
xfrm_policy_inexact_lookup_rcu(struct net *net,
                               u8 type, u16 family, u8 dir, u32 if_id);
static struct xfrm_policy *
xfrm_policy_insert_list(struct hlist_head *chain, struct xfrm_policy *policy,
                        bool excl);
static void xfrm_policy_insert_inexact_list(struct hlist_head *chain,
                                            struct xfrm_policy *policy);

static bool
xfrm_policy_find_inexact_candidates(struct xfrm_pol_inexact_candidates *cand,
                                    struct xfrm_pol_inexact_bin *b,
                                    const xfrm_address_t *saddr,
                                    const xfrm_address_t *daddr);

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;
}

/* Called with rcu_read_lock(). */
static const struct xfrm_if_cb *xfrm_if_get_cb(void)
{
        return rcu_dereference(xfrm_if_cb);
}

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);
        time64_t now = ktime_get_real_seconds();
        time64_t next = TIME64_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) {
                time64_t 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) {
                time64_t 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) {
                time64_t 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) {
                time64_t 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 != TIME64_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_inexact_list);
                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)
{
        write_lock_bh(&policy->lock);
        policy->walk.dead = 1;
        write_unlock_bh(&policy->lock);

        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 NULL;

        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(&net->xfrm.xfrm_policy_hash_generation);

        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(&net->xfrm.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);
}

/* Make sure *pol can be inserted into fastbin.
 * Useful to check that later insert requests will be successful
 * (provided xfrm_policy_lock is held throughout).
 */
static struct xfrm_pol_inexact_bin *
xfrm_policy_inexact_alloc_bin(const struct xfrm_policy *pol, u8 dir)
{
        struct xfrm_pol_inexact_bin *bin, *prev;
        struct xfrm_pol_inexact_key k = {
                .family = pol->family,
                .type = pol->type,
                .dir = dir,
                .if_id = pol->if_id,
        };
        struct net *net = xp_net(pol);

        lockdep_assert_held(&net->xfrm.xfrm_policy_lock);

        write_pnet(&k.net, net);
        bin = rhashtable_lookup_fast(&xfrm_policy_inexact_table, &k,
                                     xfrm_pol_inexact_params);
        if (bin)
                return bin;

        bin = kzalloc(sizeof(*bin), GFP_ATOMIC);
        if (!bin)
                return NULL;

        bin->k = k;
        INIT_HLIST_HEAD(&bin->hhead);
        bin->root_d = RB_ROOT;
        bin->root_s = RB_ROOT;
        seqcount_spinlock_init(&bin->count, &net->xfrm.xfrm_policy_lock);

        prev = rhashtable_lookup_get_insert_key(&xfrm_policy_inexact_table,
                                                &bin->k, &bin->head,
                                                xfrm_pol_inexact_params);
        if (!prev) {
                list_add(&bin->inexact_bins, &net->xfrm.inexact_bins);
                return bin;
        }

        kfree(bin);

        return IS_ERR(prev) ? NULL : prev;
}

static bool xfrm_pol_inexact_addr_use_any_list(const xfrm_address_t *addr,
                                               int family, u8 prefixlen)
{
        if (xfrm_addr_any(addr, family))
                return true;

        if (family == AF_INET6 && prefixlen < INEXACT_PREFIXLEN_IPV6)
                return true;

        if (family == AF_INET && prefixlen < INEXACT_PREFIXLEN_IPV4)
                return true;

        return false;
}

static bool
xfrm_policy_inexact_insert_use_any_list(const struct xfrm_policy *policy)
{
        const xfrm_address_t *addr;
        bool saddr_any, daddr_any;
        u8 prefixlen;

        addr = &policy->selector.saddr;
        prefixlen = policy->selector.prefixlen_s;

        saddr_any = xfrm_pol_inexact_addr_use_any_list(addr,
                                                       policy->family,
                                                       prefixlen);
        addr = &policy->selector.daddr;
        prefixlen = policy->selector.prefixlen_d;
        daddr_any = xfrm_pol_inexact_addr_use_any_list(addr,
                                                       policy->family,
                                                       prefixlen);
        return saddr_any && daddr_any;
}

static void xfrm_pol_inexact_node_init(struct xfrm_pol_inexact_node *node,
                                       const xfrm_address_t *addr, u8 prefixlen)
{
        node->addr = *addr;
        node->prefixlen = prefixlen;
}

static struct xfrm_pol_inexact_node *
xfrm_pol_inexact_node_alloc(const xfrm_address_t *addr, u8 prefixlen)
{
        struct xfrm_pol_inexact_node *node;

        node = kzalloc(sizeof(*node), GFP_ATOMIC);
        if (node)
                xfrm_pol_inexact_node_init(node, addr, prefixlen);

        return node;
}

static int xfrm_policy_addr_delta(const xfrm_address_t *a,
                                  const xfrm_address_t *b,
                                  u8 prefixlen, u16 family)
{
        u32 ma, mb, mask;
        unsigned int pdw, pbi;
        int delta = 0;

        switch (family) {
        case AF_INET:
                if (prefixlen == 0)
                        return 0;
                mask = ~0U << (32 - prefixlen);
                ma = ntohl(a->a4) & mask;
                mb = ntohl(b->a4) & mask;
                if (ma < mb)
                        delta = -1;
                else if (ma > mb)
                        delta = 1;
                break;
        case AF_INET6:
                pdw = prefixlen >> 5;
                pbi = prefixlen & 0x1f;

                if (pdw) {
                        delta = memcmp(a->a6, b->a6, pdw << 2);
                        if (delta)
                                return delta;
                }
                if (pbi) {
                        mask = ~0U << (32 - pbi);
                        ma = ntohl(a->a6[pdw]) & mask;
                        mb = ntohl(b->a6[pdw]) & mask;
                        if (ma < mb)
                                delta = -1;
                        else if (ma > mb)
                                delta = 1;
                }
                break;
        default:
                break;
        }

        return delta;
}

static void xfrm_policy_inexact_list_reinsert(struct net *net,
                                              struct xfrm_pol_inexact_node *n,
                                              u16 family)
{
        unsigned int matched_s, matched_d;
        struct xfrm_policy *policy, *p;

        matched_s = 0;
        matched_d = 0;

        list_for_each_entry_reverse(policy, &net->xfrm.policy_all, walk.all) {
                struct hlist_node *newpos = NULL;
                bool matches_s, matches_d;

                if (!policy->bydst_reinsert)
                        continue;

                WARN_ON_ONCE(policy->family != family);

                policy->bydst_reinsert = false;
                hlist_for_each_entry(p, &n->hhead, bydst) {
                        if (policy->priority > p->priority)
                                newpos = &p->bydst;
                        else if (policy->priority == p->priority &&
                                 policy->pos > p->pos)
                                newpos = &p->bydst;
                        else
                                break;
                }

                if (newpos)
                        hlist_add_behind_rcu(&policy->bydst, newpos);
                else
                        hlist_add_head_rcu(&policy->bydst, &n->hhead);

                /* paranoia checks follow.
                 * Check that the reinserted policy matches at least
                 * saddr or daddr for current node prefix.
                 *
                 * Matching both is fine, matching saddr in one policy
                 * (but not daddr) and then matching only daddr in another
                 * is a bug.
                 */
                matches_s = xfrm_policy_addr_delta(&policy->selector.saddr,
                                                   &n->addr,
                                                   n->prefixlen,
                                                   family) == 0;
                matches_d = xfrm_policy_addr_delta(&policy->selector.daddr,
                                                   &n->addr,
                                                   n->prefixlen,
                                                   family) == 0;
                if (matches_s && matches_d)
                        continue;

                WARN_ON_ONCE(!matches_s && !matches_d);
                if (matches_s)
                        matched_s++;
                if (matches_d)
                        matched_d++;
                WARN_ON_ONCE(matched_s && matched_d);
        }
}

static void xfrm_policy_inexact_node_reinsert(struct net *net,
                                              struct xfrm_pol_inexact_node *n,
                                              struct rb_root *new,
                                              u16 family)
{
        struct xfrm_pol_inexact_node *node;
        struct rb_node **p, *parent;

        /* we should not have another subtree here */
        WARN_ON_ONCE(!RB_EMPTY_ROOT(&n->root));
restart:
        parent = NULL;
        p = &new->rb_node;
        while (*p) {
                u8 prefixlen;
                int delta;

                parent = *p;
                node = rb_entry(*p, struct xfrm_pol_inexact_node, node);

                prefixlen = min(node->prefixlen, n->prefixlen);

                delta = xfrm_policy_addr_delta(&n->addr, &node->addr,
                                               prefixlen, family);
                if (delta < 0) {
                        p = &parent->rb_left;
                } else if (delta > 0) {
                        p = &parent->rb_right;
                } else {
                        bool same_prefixlen = node->prefixlen == n->prefixlen;
                        struct xfrm_policy *tmp;

                        hlist_for_each_entry(tmp, &n->hhead, bydst) {
                                tmp->bydst_reinsert = true;
                                hlist_del_rcu(&tmp->bydst);
                        }

                        node->prefixlen = prefixlen;

                        xfrm_policy_inexact_list_reinsert(net, node, family);

                        if (same_prefixlen) {
                                kfree_rcu(n, rcu);
                                return;
                        }

                        rb_erase(*p, new);
                        kfree_rcu(n, rcu);
                        n = node;
                        goto restart;
                }
        }

        rb_link_node_rcu(&n->node, parent, p);
        rb_insert_color(&n->node, new);
}

/* merge nodes v and n */
static void xfrm_policy_inexact_node_merge(struct net *net,
                                           struct xfrm_pol_inexact_node *v,
                                           struct xfrm_pol_inexact_node *n,
                                           u16 family)
{
        struct xfrm_pol_inexact_node *node;
        struct xfrm_policy *tmp;
        struct rb_node *rnode;

        /* To-be-merged node v has a subtree.
         *
         * Dismantle it and insert its nodes to n->root.
         */
        while ((rnode = rb_first(&v->root)) != NULL) {
                node = rb_entry(rnode, struct xfrm_pol_inexact_node, node);
                rb_erase(&node->node, &v->root);
                xfrm_policy_inexact_node_reinsert(net, node, &n->root,
                                                  family);
        }

        hlist_for_each_entry(tmp, &v->hhead, bydst) {
                tmp->bydst_reinsert = true;
                hlist_del_rcu(&tmp->bydst);
        }

        xfrm_policy_inexact_list_reinsert(net, n, family);
}

static struct xfrm_pol_inexact_node *
xfrm_policy_inexact_insert_node(struct net *net,
                                struct rb_root *root,
                                xfrm_address_t *addr,
                                u16 family, u8 prefixlen, u8 dir)
{
        struct xfrm_pol_inexact_node *cached = NULL;
        struct rb_node **p, *parent = NULL;
        struct xfrm_pol_inexact_node *node;

        p = &root->rb_node;
        while (*p) {
                int delta;

                parent = *p;

                node = rb_entry(*p, struct xfrm_pol_inexact_node, node);

                delta = xfrm_policy_addr_delta(addr, &node->addr,
                                               node->prefixlen,
                                               family);
                if (delta == 0 && prefixlen >= node->prefixlen) {
                        WARN_ON_ONCE(cached); /* ipsec policies got lost */
                        return node;
                }

                if (delta < 0)
                        p = &parent->rb_left;
                else
                        p = &parent->rb_right;

                if (prefixlen < node->prefixlen) {
                        delta = xfrm_policy_addr_delta(addr, &node->addr,
                                                       prefixlen,
                                                       family);
                        if (delta)
                                continue;

                        /* This node is a subnet of the new prefix. It needs
                         * to be removed and re-inserted with the smaller
                         * prefix and all nodes that are now also covered
                         * by the reduced prefixlen.
                         */
                        rb_erase(&node->node, root);

                        if (!cached) {
                                xfrm_pol_inexact_node_init(node, addr,
                                                           prefixlen);
                                cached = node;
                        } else {
                                /* This node also falls within the new
                                 * prefixlen. Merge the to-be-reinserted
                                 * node and this one.
                                 */
                                xfrm_policy_inexact_node_merge(net, node,
                                                               cached, family);
                                kfree_rcu(node, rcu);
                        }

                        /* restart */
                        p = &root->rb_node;
                        parent = NULL;
                }
        }

        node = cached;
        if (!node) {
                node = xfrm_pol_inexact_node_alloc(addr, prefixlen);
                if (!node)
                        return NULL;
        }

        rb_link_node_rcu(&node->node, parent, p);
        rb_insert_color(&node->node, root);

        return node;
}

static void xfrm_policy_inexact_gc_tree(struct rb_root *r, bool rm)
{
        struct xfrm_pol_inexact_node *node;
        struct rb_node *rn = rb_first(r);

        while (rn) {
                node = rb_entry(rn, struct xfrm_pol_inexact_node, node);

                xfrm_policy_inexact_gc_tree(&node->root, rm);
                rn = rb_next(rn);

                if (!hlist_empty(&node->hhead) || !RB_EMPTY_ROOT(&node->root)) {
                        WARN_ON_ONCE(rm);
                        continue;
                }

                rb_erase(&node->node, r);
                kfree_rcu(node, rcu);
        }
}

static void __xfrm_policy_inexact_prune_bin(struct xfrm_pol_inexact_bin *b, bool net_exit)
{
        write_seqcount_begin(&b->count);
        xfrm_policy_inexact_gc_tree(&b->root_d, net_exit);
        xfrm_policy_inexact_gc_tree(&b->root_s, net_exit);
        write_seqcount_end(&b->count);

        if (!RB_EMPTY_ROOT(&b->root_d) || !RB_EMPTY_ROOT(&b->root_s) ||
            !hlist_empty(&b->hhead)) {
                WARN_ON_ONCE(net_exit);
                return;
        }

        if (rhashtable_remove_fast(&xfrm_policy_inexact_table, &b->head,
                                   xfrm_pol_inexact_params) == 0) {
                list_del(&b->inexact_bins);
                kfree_rcu(b, rcu);
        }
}

static void xfrm_policy_inexact_prune_bin(struct xfrm_pol_inexact_bin *b)
{
        struct net *net = read_pnet(&b->k.net);

        spin_lock_bh(&net->xfrm.xfrm_policy_lock);
        __xfrm_policy_inexact_prune_bin(b, false);
        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
}

static void __xfrm_policy_inexact_flush(struct net *net)
{
        struct xfrm_pol_inexact_bin *bin, *t;

        lockdep_assert_held(&net->xfrm.xfrm_policy_lock);

        list_for_each_entry_safe(bin, t, &net->xfrm.inexact_bins, inexact_bins)
                __xfrm_policy_inexact_prune_bin(bin, false);
}

static struct hlist_head *
xfrm_policy_inexact_alloc_chain(struct xfrm_pol_inexact_bin *bin,
                                struct xfrm_policy *policy, u8 dir)
{
        struct xfrm_pol_inexact_node *n;
        struct net *net;

        net = xp_net(policy);
        lockdep_assert_held(&net->xfrm.xfrm_policy_lock);

        if (xfrm_policy_inexact_insert_use_any_list(policy))
                return &bin->hhead;

        if (xfrm_pol_inexact_addr_use_any_list(&policy->selector.daddr,
                                               policy->family,
                                               policy->selector.prefixlen_d)) {
                write_seqcount_begin(&bin->count);
                n = xfrm_policy_inexact_insert_node(net,
                                                    &bin->root_s,
                                                    &policy->selector.saddr,
                                                    policy->family,
                                                    policy->selector.prefixlen_s,
                                                    dir);
                write_seqcount_end(&bin->count);
                if (!n)
                        return NULL;

                return &n->hhead;
        }

        /* daddr is fixed */
        write_seqcount_begin(&bin->count);
        n = xfrm_policy_inexact_insert_node(net,
                                            &bin->root_d,
                                            &policy->selector.daddr,
                                            policy->family,
                                            policy->selector.prefixlen_d, dir);
        write_seqcount_end(&bin->count);
        if (!n)
                return NULL;

        /* saddr is wildcard */
        if (xfrm_pol_inexact_addr_use_any_list(&policy->selector.saddr,
                                               policy->family,
                                               policy->selector.prefixlen_s))
                return &n->hhead;

        write_seqcount_begin(&bin->count);
        n = xfrm_policy_inexact_insert_node(net,
                                            &n->root,
                                            &policy->selector.saddr,
                                            policy->family,
                                            policy->selector.prefixlen_s, dir);
        write_seqcount_end(&bin->count);
        if (!n)
                return NULL;

        return &n->hhead;
}

static struct xfrm_policy *
xfrm_policy_inexact_insert(struct xfrm_policy *policy, u8 dir, int excl)
{
        struct xfrm_pol_inexact_bin *bin;
        struct xfrm_policy *delpol;
        struct hlist_head *chain;
        struct net *net;

        bin = xfrm_policy_inexact_alloc_bin(policy, dir);
        if (!bin)
                return ERR_PTR(-ENOMEM);

        net = xp_net(policy);
        lockdep_assert_held(&net->xfrm.xfrm_policy_lock);

        chain = xfrm_policy_inexact_alloc_chain(bin, policy, dir);
        if (!chain) {
                __xfrm_policy_inexact_prune_bin(bin, false);
                return ERR_PTR(-ENOMEM);
        }

        delpol = xfrm_policy_insert_list(chain, policy, excl);
        if (delpol && excl) {
                __xfrm_policy_inexact_prune_bin(bin, false);
                return ERR_PTR(-EEXIST);
        }

        chain = &net->xfrm.policy_inexact[dir];
        xfrm_policy_insert_inexact_list(chain, policy);

        if (delpol)
                __xfrm_policy_inexact_prune_bin(bin, false);

        return delpol;
}

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

        /* make sure that we can insert the indirect policies again before
         * we start with destructive action.
         */
        list_for_each_entry(policy, &net->xfrm.policy_all, walk.all) {
                struct xfrm_pol_inexact_bin *bin;
                u8 dbits, sbits;

                dir = xfrm_policy_id2dir(policy->index);
                if (policy->walk.dead || dir >= XFRM_POLICY_MAX)
                        continue;

                if ((dir & XFRM_POLICY_MASK) == XFRM_POLICY_OUT) {
                        if (policy->family == AF_INET) {
                                dbits = rbits4;
                                sbits = lbits4;
                        } else {
                                dbits = rbits6;
                                sbits = lbits6;
                        }
                } else {
                        if (policy->family == AF_INET) {
                                dbits = lbits4;
                                sbits = rbits4;
                        } else {
                                dbits = lbits6;
                                sbits = rbits6;
                        }
                }

                if (policy->selector.prefixlen_d < dbits ||
                    policy->selector.prefixlen_s < sbits)
                        continue;

                bin = xfrm_policy_inexact_alloc_bin(policy, dir);
                if (!bin)
                        goto out_unlock;

                if (!xfrm_policy_inexact_alloc_chain(bin, policy, dir))
                        goto out_unlock;
        }

        /* reset the bydst and inexact table in all directions */
        for (dir = 0; dir < XFRM_POLICY_MAX; dir++) {
                struct hlist_node *n;

                hlist_for_each_entry_safe(policy, n,
                                          &net->xfrm.policy_inexact[dir],
                                          bydst_inexact_list) {
                        hlist_del_rcu(&policy->bydst);
                        hlist_del_init(&policy->bydst_inexact_list);
                }

                hmask = net->xfrm.policy_bydst[dir].hmask;
                odst = net->xfrm.policy_bydst[dir].table;
                for (i = hmask; i >= 0; i--) {
                        hlist_for_each_entry_safe(policy, n, odst + i, bydst)
                                hlist_del_rcu(&policy->bydst);
                }
                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)
                        continue;
                dir = xfrm_policy_id2dir(policy->index);
                if (dir >= XFRM_POLICY_MAX) {
                        /* skip socket policies */
                        continue;
                }
                newpos = NULL;
                chain = policy_hash_bysel(net, &policy->selector,
                                          policy->family, dir);

                if (!chain) {
                        void *p = xfrm_policy_inexact_insert(policy, dir, 0);

                        WARN_ONCE(IS_ERR(p), "reinsert: %ld\n", PTR_ERR(p));
                        continue;
                }

                hlist_for_each_entry(pol, chain, bydst) {
                        if (policy->priority >= pol->priority)
                                newpos = &pol->bydst;
                        else
                                break;
                }
                if (newpos)
                        hlist_add_behind_rcu(&policy->bydst, newpos);
                else
                        hlist_add_head_rcu(&policy->bydst, chain);
        }

out_unlock:
        __xfrm_policy_inexact_flush(net);
        write_seqcount_end(&net->xfrm.xfrm_policy_hash_generation);
        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 inline bool xfrm_policy_mark_match(const struct xfrm_mark *mark,
                                          struct xfrm_policy *pol)
{
        return mark->v == pol->mark.v && mark->m == pol->mark.m;
}

static u32 xfrm_pol_bin_key(const void *data, u32 len, u32 seed)
{
        const struct xfrm_pol_inexact_key *k = data;
        u32 a = k->type << 24 | k->dir << 16 | k->family;

        return jhash_3words(a, k->if_id, net_hash_mix(read_pnet(&k->net)),
                            seed);
}

static u32 xfrm_pol_bin_obj(const void *data, u32 len, u32 seed)
{
        const struct xfrm_pol_inexact_bin *b = data;

        return xfrm_pol_bin_key(&b->k, 0, seed);
}

static int xfrm_pol_bin_cmp(struct rhashtable_compare_arg *arg,
                            const void *ptr)
{
        const struct xfrm_pol_inexact_key *key = arg->key;
        const struct xfrm_pol_inexact_bin *b = ptr;
        int ret;

        if (!net_eq(read_pnet(&b->k.net), read_pnet(&key->net)))
                return -1;

        ret = b->k.dir ^ key->dir;
        if (ret)
                return ret;

        ret = b->k.type ^ key->type;
        if (ret)
                return ret;

        ret = b->k.family ^ key->family;
        if (ret)
                return ret;

        return b->k.if_id ^ key->if_id;
}

static const struct rhashtable_params xfrm_pol_inexact_params = {
        .head_offset            = offsetof(struct xfrm_pol_inexact_bin, head),
        .hashfn                 = xfrm_pol_bin_key,
        .obj_hashfn             = xfrm_pol_bin_obj,
        .obj_cmpfn              = xfrm_pol_bin_cmp,
        .automatic_shrinking    = true,
};

static void xfrm_policy_insert_inexact_list(struct hlist_head *chain,
                                            struct xfrm_policy *policy)
{
        struct xfrm_policy *pol, *delpol = NULL;
        struct hlist_node *newpos = NULL;
        int i = 0;

        hlist_for_each_entry(pol, chain, bydst_inexact_list) {
                if (pol->type == policy->type &&
                    pol->if_id == policy->if_id &&
                    !selector_cmp(&pol->selector, &policy->selector) &&
                    xfrm_policy_mark_match(&policy->mark, pol) &&
                    xfrm_sec_ctx_match(pol->security, policy->security) &&
                    !WARN_ON(delpol)) {
                        delpol = pol;
                        if (policy->priority > pol->priority)
                                continue;
                } else if (policy->priority >= pol->priority) {
                        newpos = &pol->bydst_inexact_list;
                        continue;
                }
                if (delpol)
                        break;
        }

        if (newpos)
                hlist_add_behind_rcu(&policy->bydst_inexact_list, newpos);
        else
                hlist_add_head_rcu(&policy->bydst_inexact_list, chain);

        hlist_for_each_entry(pol, chain, bydst_inexact_list) {
                pol->pos = i;
                i++;
        }
}

static struct xfrm_policy *xfrm_policy_insert_list(struct hlist_head *chain,
                                                   struct xfrm_policy *policy,
                                                   bool excl)
{
        struct xfrm_policy *pol, *newpos = NULL, *delpol = NULL;

        hlist_for_each_entry(pol, chain, bydst) {
                if (pol->type == policy->type &&
                    pol->if_id == policy->if_id &&
                    !selector_cmp(&pol->selector, &policy->selector) &&
                    xfrm_policy_mark_match(&policy->mark, pol) &&
                    xfrm_sec_ctx_match(pol->security, policy->security) &&
                    !WARN_ON(delpol)) {
                        if (excl)
                                return ERR_PTR(-EEXIST);
                        delpol = pol;
                        if (policy->priority > pol->priority)
                                continue;
                } else if (policy->priority >= pol->priority) {
                        newpos = pol;
                        continue;
                }
                if (delpol)
                        break;
        }

        if (newpos)
                hlist_add_behind_rcu(&policy->bydst, &newpos->bydst);
        else
                hlist_add_head_rcu(&policy->bydst, chain);

        return delpol;
}

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

        spin_lock_bh(&net->xfrm.xfrm_policy_lock);
        chain = policy_hash_bysel(net, &policy->selector, policy->family, dir);
        if (chain)
                delpol = xfrm_policy_insert_list(chain, policy, excl);
        else
                delpol = xfrm_policy_inexact_insert(policy, dir, excl);

        if (IS_ERR(delpol)) {
                spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
                return PTR_ERR(delpol);
        }

        __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 = ktime_get_real_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);

static struct xfrm_policy *
__xfrm_policy_bysel_ctx(struct hlist_head *chain, const struct xfrm_mark *mark,
                        u32 if_id, u8 type, int dir, struct xfrm_selector *sel,
                        struct xfrm_sec_ctx *ctx)
{
        struct xfrm_policy *pol;

        if (!chain)
                return NULL;

        hlist_for_each_entry(pol, chain, bydst) {
                if (pol->type == type &&
                    pol->if_id == if_id &&
                    xfrm_policy_mark_match(mark, pol) &&
                    !selector_cmp(sel, &pol->selector) &&
                    xfrm_sec_ctx_match(ctx, pol->security))
                        return pol;
        }

        return NULL;
}

struct xfrm_policy *
xfrm_policy_bysel_ctx(struct net *net, const struct xfrm_mark *mark, u32 if_id,
                      u8 type, int dir, struct xfrm_selector *sel,
                      struct xfrm_sec_ctx *ctx, int delete, int *err)
{
        struct xfrm_pol_inexact_bin *bin = NULL;
        struct xfrm_policy *pol, *ret = NULL;
        struct hlist_head *chain;

        *err = 0;
        spin_lock_bh(&net->xfrm.xfrm_policy_lock);
        chain = policy_hash_bysel(net, sel, sel->family, dir);
        if (!chain) {
                struct xfrm_pol_inexact_candidates cand;
                int i;

                bin = xfrm_policy_inexact_lookup(net, type,
                                                 sel->family, dir, if_id);
                if (!bin) {
                        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
                        return NULL;
                }

                if (!xfrm_policy_find_inexact_candidates(&cand, bin,
                                                         &sel->saddr,
                                                         &sel->daddr)) {
                        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
                        return NULL;
                }

                pol = NULL;
                for (i = 0; i < ARRAY_SIZE(cand.res); i++) {
                        struct xfrm_policy *tmp;

                        tmp = __xfrm_policy_bysel_ctx(cand.res[i], mark,
                                                      if_id, type, dir,
                                                      sel, ctx);
                        if (!tmp)
                                continue;

                        if (!pol || tmp->pos < pol->pos)
                                pol = tmp;
                }
        } else {
                pol = __xfrm_policy_bysel_ctx(chain, mark, if_id, type, dir,
                                              sel, ctx);
        }

        if (pol) {
                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;
        }
        spin_unlock_bh(&net->xfrm.xfrm_policy_lock);

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

struct xfrm_policy *
xfrm_policy_byid(struct net *net, const struct xfrm_mark *mark, u32 if_id,
                 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 &&
                    pol->if_id == if_id && xfrm_policy_mark_match(mark, pol)) {
                        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)
{
        struct xfrm_policy *pol;
        int err = 0;

        list_for_each_entry(pol, &net->xfrm.policy_all, walk.all) {
                if (pol->walk.dead ||
                    xfrm_policy_id2dir(pol->index) >= XFRM_POLICY_MAX ||
                    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;
        struct xfrm_policy *pol;

        spin_lock_bh(&net->xfrm.xfrm_policy_lock);

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

again:
        list_for_each_entry(pol, &net->xfrm.policy_all, walk.all) {
                dir = xfrm_policy_id2dir(pol->index);
                if (pol->walk.dead ||
                    dir >= XFRM_POLICY_MAX ||
                    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 again;
        }
        if (cnt)
                __xfrm_policy_inexact_flush(net);
        else
                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, u32 if_id)
{
        const struct xfrm_selector *sel = &pol->selector;
        int ret = -ESRCH;
        bool match;

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

static struct xfrm_pol_inexact_node *
xfrm_policy_lookup_inexact_addr(const struct rb_root *r,
                                seqcount_spinlock_t *count,
                                const xfrm_address_t *addr, u16 family)
{
        const struct rb_node *parent;
        int seq;

again:
        seq = read_seqcount_begin(count);

        parent = rcu_dereference_raw(r->rb_node);
        while (parent) {
                struct xfrm_pol_inexact_node *node;
                int delta;

                node = rb_entry(parent, struct xfrm_pol_inexact_node, node);

                delta = xfrm_policy_addr_delta(addr, &node->addr,
                                               node->prefixlen, family);
                if (delta < 0) {
                        parent = rcu_dereference_raw(parent->rb_left);
                        continue;
                } else if (delta > 0) {
                        parent = rcu_dereference_raw(parent->rb_right);
                        continue;
                }

                return node;
        }

        if (read_seqcount_retry(count, seq))
                goto again;

        return NULL;
}

static bool
xfrm_policy_find_inexact_candidates(struct xfrm_pol_inexact_candidates *cand,
                                    struct xfrm_pol_inexact_bin *b,
                                    const xfrm_address_t *saddr,
                                    const xfrm_address_t *daddr)
{
        struct xfrm_pol_inexact_node *n;
        u16 family;

        if (!b)
                return false;

        family = b->k.family;
        memset(cand, 0, sizeof(*cand));
        cand->res[XFRM_POL_CAND_ANY] = &b->hhead;

        n = xfrm_policy_lookup_inexact_addr(&b->root_d, &b->count, daddr,
                                            family);
        if (n) {
                cand->res[XFRM_POL_CAND_DADDR] = &n->hhead;
                n = xfrm_policy_lookup_inexact_addr(&n->root, &b->count, saddr,
                                                    family);
                if (n)
                        cand->res[XFRM_POL_CAND_BOTH] = &n->hhead;
        }

        n = xfrm_policy_lookup_inexact_addr(&b->root_s, &b->count, saddr,
                                            family);
        if (n)
                cand->res[XFRM_POL_CAND_SADDR] = &n->hhead;

        return true;
}

static struct xfrm_pol_inexact_bin *
xfrm_policy_inexact_lookup_rcu(struct net *net, u8 type, u16 family,
                               u8 dir, u32 if_id)
{
        struct xfrm_pol_inexact_key k = {
                .family = family,
                .type = type,
                .dir = dir,
                .if_id = if_id,
        };

        write_pnet(&k.net, net);

        return rhashtable_lookup(&xfrm_policy_inexact_table, &k,
                                 xfrm_pol_inexact_params);
}

static struct xfrm_pol_inexact_bin *
xfrm_policy_inexact_lookup(struct net *net, u8 type, u16 family,
                           u8 dir, u32 if_id)
{
        struct xfrm_pol_inexact_bin *bin;