root/net/ipv6/ip6_flowlabel.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      ip6_flowlabel.c         IPv6 flowlabel manager.
 *
 *      Authors:        Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 */

#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/in6.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/pid_namespace.h>
#include <linux/jump_label_ratelimit.h>

#include <net/net_namespace.h>
#include <net/sock.h>

#include <net/ipv6.h>
#include <net/rawv6.h>
#include <net/transp_v6.h>

#include <linux/uaccess.h>

#define FL_MIN_LINGER   6       /* Minimal linger. It is set to 6sec specified
                                   in old IPv6 RFC. Well, it was reasonable value.
                                 */
#define FL_MAX_LINGER   150     /* Maximal linger timeout */

/* FL hash table */

#define FL_MAX_PER_SOCK 32
#define FL_MAX_SIZE     4096
#define FL_HASH_MASK    255
#define FL_HASH(l)      (ntohl(l)&FL_HASH_MASK)

static atomic_t fl_size = ATOMIC_INIT(0);
static struct ip6_flowlabel __rcu *fl_ht[FL_HASH_MASK+1];

static void ip6_fl_gc(struct timer_list *unused);
static DEFINE_TIMER(ip6_fl_gc_timer, ip6_fl_gc);

/* FL hash table lock: it protects only of GC */

static DEFINE_SPINLOCK(ip6_fl_lock);

/* Big socket sock */

static DEFINE_SPINLOCK(ip6_sk_fl_lock);

DEFINE_STATIC_KEY_DEFERRED_FALSE(ipv6_flowlabel_exclusive, HZ);
EXPORT_SYMBOL(ipv6_flowlabel_exclusive);

#define for_each_fl_rcu(hash, fl)                               \
        for (fl = rcu_dereference(fl_ht[(hash)]);               \
             fl != NULL;                                        \
             fl = rcu_dereference(fl->next))
#define for_each_fl_continue_rcu(fl)                            \
        for (fl = rcu_dereference(fl->next);                    \
             fl != NULL;                                        \
             fl = rcu_dereference(fl->next))

#define for_each_sk_fl_rcu(sk, sfl)                             \
        for (sfl = rcu_dereference(inet_sk(sk)->ipv6_fl_list);  \
             sfl != NULL;                                       \
             sfl = rcu_dereference(sfl->next))

static inline struct ip6_flowlabel *__fl_lookup(struct net *net, __be32 label)
{
        struct ip6_flowlabel *fl;

        for_each_fl_rcu(FL_HASH(label), fl) {
                if (fl->label == label && net_eq(fl->fl_net, net))
                        return fl;
        }
        return NULL;
}

static struct ip6_flowlabel *fl_lookup(struct net *net, __be32 label)
{
        struct ip6_flowlabel *fl;

        rcu_read_lock();
        fl = __fl_lookup(net, label);
        if (fl && !atomic_inc_not_zero(&fl->users))
                fl = NULL;
        rcu_read_unlock();
        return fl;
}

static bool fl_shared_exclusive(struct ip6_flowlabel *fl)
{
        return fl->share == IPV6_FL_S_EXCL ||
               fl->share == IPV6_FL_S_PROCESS ||
               fl->share == IPV6_FL_S_USER;
}

static void fl_free_rcu(struct rcu_head *head)
{
        struct ip6_flowlabel *fl = container_of(head, struct ip6_flowlabel, rcu);

        if (fl->share == IPV6_FL_S_PROCESS)
                put_pid(fl->owner.pid);
        kfree(fl->opt);
        kfree(fl);
}


static void fl_free(struct ip6_flowlabel *fl)
{
        if (!fl)
                return;

        if (fl_shared_exclusive(fl) || fl->opt)
                static_branch_slow_dec_deferred(&ipv6_flowlabel_exclusive);

        call_rcu(&fl->rcu, fl_free_rcu);
}

static void fl_release(struct ip6_flowlabel *fl)
{
        spin_lock_bh(&ip6_fl_lock);

        fl->lastuse = jiffies;
        if (atomic_dec_and_test(&fl->users)) {
                unsigned long ttd = fl->lastuse + fl->linger;
                if (time_after(ttd, fl->expires))
                        fl->expires = ttd;
                ttd = fl->expires;
                if (!timer_pending(&ip6_fl_gc_timer) ||
                    time_after(ip6_fl_gc_timer.expires, ttd))
                        mod_timer(&ip6_fl_gc_timer, ttd);
        }
        spin_unlock_bh(&ip6_fl_lock);
}

static void ip6_fl_gc(struct timer_list *unused)
{
        int i;
        unsigned long now = jiffies;
        unsigned long sched = 0;

        spin_lock(&ip6_fl_lock);

        for (i = 0; i <= FL_HASH_MASK; i++) {
                struct ip6_flowlabel *fl;
                struct ip6_flowlabel __rcu **flp;

                flp = &fl_ht[i];
                while ((fl = rcu_dereference_protected(*flp,
                                                       lockdep_is_held(&ip6_fl_lock))) != NULL) {
                        if (atomic_read(&fl->users) == 0) {
                                unsigned long ttd = fl->lastuse + fl->linger;
                                if (time_after(ttd, fl->expires))
                                        fl->expires = ttd;
                                ttd = fl->expires;
                                if (time_after_eq(now, ttd)) {
                                        *flp = fl->next;
                                        fl_free(fl);
                                        atomic_dec(&fl_size);
                                        continue;
                                }
                                if (!sched || time_before(ttd, sched))
                                        sched = ttd;
                        }
                        flp = &fl->next;
                }
        }
        if (!sched && atomic_read(&fl_size))
                sched = now + FL_MAX_LINGER;
        if (sched) {
                mod_timer(&ip6_fl_gc_timer, sched);
        }
        spin_unlock(&ip6_fl_lock);
}

static void __net_exit ip6_fl_purge(struct net *net)
{
        int i;

        spin_lock_bh(&ip6_fl_lock);
        for (i = 0; i <= FL_HASH_MASK; i++) {
                struct ip6_flowlabel *fl;
                struct ip6_flowlabel __rcu **flp;

                flp = &fl_ht[i];
                while ((fl = rcu_dereference_protected(*flp,
                                                       lockdep_is_held(&ip6_fl_lock))) != NULL) {
                        if (net_eq(fl->fl_net, net) &&
                            atomic_read(&fl->users) == 0) {
                                *flp = fl->next;
                                fl_free(fl);
                                atomic_dec(&fl_size);
                                continue;
                        }
                        flp = &fl->next;
                }
        }
        spin_unlock_bh(&ip6_fl_lock);
}

static struct ip6_flowlabel *fl_intern(struct net *net,
                                       struct ip6_flowlabel *fl, __be32 label)
{
        struct ip6_flowlabel *lfl;

        fl->label = label & IPV6_FLOWLABEL_MASK;

        rcu_read_lock();
        spin_lock_bh(&ip6_fl_lock);
        if (label == 0) {
                for (;;) {
                        fl->label = htonl(get_random_u32())&IPV6_FLOWLABEL_MASK;
                        if (fl->label) {
                                lfl = __fl_lookup(net, fl->label);
                                if (!lfl)
                                        break;
                        }
                }
        } else {
                /*
                 * we dropper the ip6_fl_lock, so this entry could reappear
                 * and we need to recheck with it.
                 *
                 * OTOH no need to search the active socket first, like it is
                 * done in ipv6_flowlabel_opt - sock is locked, so new entry
                 * with the same label can only appear on another sock
                 */
                lfl = __fl_lookup(net, fl->label);
                if (lfl) {
                        atomic_inc(&lfl->users);
                        spin_unlock_bh(&ip6_fl_lock);
                        rcu_read_unlock();
                        return lfl;
                }
        }

        fl->lastuse = jiffies;
        fl->next = fl_ht[FL_HASH(fl->label)];
        rcu_assign_pointer(fl_ht[FL_HASH(fl->label)], fl);
        atomic_inc(&fl_size);
        spin_unlock_bh(&ip6_fl_lock);
        rcu_read_unlock();
        return NULL;
}



/* Socket flowlabel lists */

struct ip6_flowlabel *__fl6_sock_lookup(struct sock *sk, __be32 label)
{
        struct ipv6_fl_socklist *sfl;

        label &= IPV6_FLOWLABEL_MASK;

        rcu_read_lock();
        for_each_sk_fl_rcu(sk, sfl) {
                struct ip6_flowlabel *fl = sfl->fl;

                if (fl->label == label && atomic_inc_not_zero(&fl->users)) {
                        fl->lastuse = jiffies;
                        rcu_read_unlock();
                        return fl;
                }
        }
        rcu_read_unlock();
        return NULL;
}
EXPORT_SYMBOL_GPL(__fl6_sock_lookup);

void fl6_free_socklist(struct sock *sk)
{
        struct inet_sock *inet = inet_sk(sk);
        struct ipv6_fl_socklist *sfl;

        if (!rcu_access_pointer(inet->ipv6_fl_list))
                return;

        spin_lock_bh(&ip6_sk_fl_lock);
        while ((sfl = rcu_dereference_protected(inet->ipv6_fl_list,
                                                lockdep_is_held(&ip6_sk_fl_lock))) != NULL) {
                inet->ipv6_fl_list = sfl->next;
                spin_unlock_bh(&ip6_sk_fl_lock);

                fl_release(sfl->fl);
                kfree_rcu(sfl, rcu);

                spin_lock_bh(&ip6_sk_fl_lock);
        }
        spin_unlock_bh(&ip6_sk_fl_lock);
}

/* Service routines */


/*
   It is the only difficult place. flowlabel enforces equal headers
   before and including routing header, however user may supply options
   following rthdr.
 */

struct ipv6_txoptions *fl6_merge_options(struct ipv6_txoptions *opt_space,
                                         struct ip6_flowlabel *fl,
                                         struct ipv6_txoptions *fopt)
{
        struct ipv6_txoptions *fl_opt = fl->opt;

        if (!fopt || fopt->opt_flen == 0)
                return fl_opt;

        if (fl_opt) {
                opt_space->hopopt = fl_opt->hopopt;
                opt_space->dst0opt = fl_opt->dst0opt;
                opt_space->srcrt = fl_opt->srcrt;
                opt_space->opt_nflen = fl_opt->opt_nflen;
        } else {
                if (fopt->opt_nflen == 0)
                        return fopt;
                opt_space->hopopt = NULL;
                opt_space->dst0opt = NULL;
                opt_space->srcrt = NULL;
                opt_space->opt_nflen = 0;
        }
        opt_space->dst1opt = fopt->dst1opt;
        opt_space->opt_flen = fopt->opt_flen;
        opt_space->tot_len = fopt->tot_len;
        return opt_space;
}
EXPORT_SYMBOL_GPL(fl6_merge_options);

static unsigned long check_linger(unsigned long ttl)
{
        if (ttl < FL_MIN_LINGER)
                return FL_MIN_LINGER*HZ;
        if (ttl > FL_MAX_LINGER && !capable(CAP_NET_ADMIN))
                return 0;
        return ttl*HZ;
}

static int fl6_renew(struct ip6_flowlabel *fl, unsigned long linger, unsigned long expires)
{
        linger = check_linger(linger);
        if (!linger)
                return -EPERM;
        expires = check_linger(expires);
        if (!expires)
                return -EPERM;

        spin_lock_bh(&ip6_fl_lock);
        fl->lastuse = jiffies;
        if (time_before(fl->linger, linger))
                fl->linger = linger;
        if (time_before(expires, fl->linger))
                expires = fl->linger;
        if (time_before(fl->expires, fl->lastuse + expires))
                fl->expires = fl->lastuse + expires;
        spin_unlock_bh(&ip6_fl_lock);

        return 0;
}

static struct ip6_flowlabel *
fl_create(struct net *net, struct sock *sk, struct in6_flowlabel_req *freq,
          sockptr_t optval, int optlen, int *err_p)
{
        struct ip6_flowlabel *fl = NULL;
        int olen;
        int addr_type;
        int err;

        olen = optlen - CMSG_ALIGN(sizeof(*freq));
        err = -EINVAL;
        if (olen > 64 * 1024)
                goto done;

        err = -ENOMEM;
        fl = kzalloc_obj(*fl);
        if (!fl)
                goto done;

        if (olen > 0) {
                struct msghdr msg;
                struct flowi6 flowi6;
                struct ipcm6_cookie ipc6;

                err = -ENOMEM;
                fl->opt = kmalloc(sizeof(*fl->opt) + olen, GFP_KERNEL);
                if (!fl->opt)
                        goto done;

                memset(fl->opt, 0, sizeof(*fl->opt));
                fl->opt->tot_len = sizeof(*fl->opt) + olen;
                err = -EFAULT;
                if (copy_from_sockptr_offset(fl->opt + 1, optval,
                                CMSG_ALIGN(sizeof(*freq)), olen))
                        goto done;

                msg.msg_controllen = olen;
                msg.msg_control = (void *)(fl->opt+1);
                memset(&flowi6, 0, sizeof(flowi6));

                ipc6.opt = fl->opt;
                err = ip6_datagram_send_ctl(net, sk, &msg, &flowi6, &ipc6);
                if (err)
                        goto done;
                err = -EINVAL;
                if (fl->opt->opt_flen)
                        goto done;
                if (fl->opt->opt_nflen == 0) {
                        kfree(fl->opt);
                        fl->opt = NULL;
                }
        }

        fl->fl_net = net;
        fl->expires = jiffies;
        err = fl6_renew(fl, freq->flr_linger, freq->flr_expires);
        if (err)
                goto done;
        fl->share = freq->flr_share;
        addr_type = ipv6_addr_type(&freq->flr_dst);
        if ((addr_type & IPV6_ADDR_MAPPED) ||
            addr_type == IPV6_ADDR_ANY) {
                err = -EINVAL;
                goto done;
        }
        fl->dst = freq->flr_dst;
        atomic_set(&fl->users, 1);
        switch (fl->share) {
        case IPV6_FL_S_EXCL:
        case IPV6_FL_S_ANY:
                break;
        case IPV6_FL_S_PROCESS:
                fl->owner.pid = get_task_pid(current, PIDTYPE_PID);
                break;
        case IPV6_FL_S_USER:
                fl->owner.uid = current_euid();
                break;
        default:
                err = -EINVAL;
                goto done;
        }
        if (fl_shared_exclusive(fl) || fl->opt) {
                WRITE_ONCE(sock_net(sk)->ipv6.flowlabel_has_excl, 1);
                static_branch_deferred_inc(&ipv6_flowlabel_exclusive);
        }
        return fl;

done:
        if (fl) {
                kfree(fl->opt);
                kfree(fl);
        }
        *err_p = err;
        return NULL;
}

static int mem_check(struct sock *sk)
{
        int room = FL_MAX_SIZE - atomic_read(&fl_size);
        struct ipv6_fl_socklist *sfl;
        int count = 0;

        if (room > FL_MAX_SIZE - FL_MAX_PER_SOCK)
                return 0;

        rcu_read_lock();
        for_each_sk_fl_rcu(sk, sfl)
                count++;
        rcu_read_unlock();

        if (room <= 0 ||
            ((count >= FL_MAX_PER_SOCK ||
              (count > 0 && room < FL_MAX_SIZE/2) || room < FL_MAX_SIZE/4) &&
             !capable(CAP_NET_ADMIN)))
                return -ENOBUFS;

        return 0;
}

static inline void fl_link(struct sock *sk, struct ipv6_fl_socklist *sfl,
                           struct ip6_flowlabel *fl)
{
        struct inet_sock *inet = inet_sk(sk);

        spin_lock_bh(&ip6_sk_fl_lock);
        sfl->fl = fl;
        sfl->next = inet->ipv6_fl_list;
        rcu_assign_pointer(inet->ipv6_fl_list, sfl);
        spin_unlock_bh(&ip6_sk_fl_lock);
}

int ipv6_flowlabel_opt_get(struct sock *sk, struct in6_flowlabel_req *freq,
                           int flags)
{
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct ipv6_fl_socklist *sfl;

        if (flags & IPV6_FL_F_REMOTE) {
                freq->flr_label = np->rcv_flowinfo & IPV6_FLOWLABEL_MASK;
                return 0;
        }

        if (inet6_test_bit(REPFLOW, sk)) {
                freq->flr_label = np->flow_label;
                return 0;
        }

        rcu_read_lock();

        for_each_sk_fl_rcu(sk, sfl) {
                if (sfl->fl->label == (np->flow_label & IPV6_FLOWLABEL_MASK)) {
                        spin_lock_bh(&ip6_fl_lock);
                        freq->flr_label = sfl->fl->label;
                        freq->flr_dst = sfl->fl->dst;
                        freq->flr_share = sfl->fl->share;
                        freq->flr_expires = (sfl->fl->expires - jiffies) / HZ;
                        freq->flr_linger = sfl->fl->linger / HZ;

                        spin_unlock_bh(&ip6_fl_lock);
                        rcu_read_unlock();
                        return 0;
                }
        }
        rcu_read_unlock();

        return -ENOENT;
}

#define socklist_dereference(__sflp) \
        rcu_dereference_protected(__sflp, lockdep_is_held(&ip6_sk_fl_lock))

static int ipv6_flowlabel_put(struct sock *sk, struct in6_flowlabel_req *freq)
{
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct ipv6_fl_socklist __rcu **sflp;
        struct ipv6_fl_socklist *sfl;

        if (freq->flr_flags & IPV6_FL_F_REFLECT) {
                if (sk->sk_protocol != IPPROTO_TCP)
                        return -ENOPROTOOPT;
                if (!inet6_test_bit(REPFLOW, sk))
                        return -ESRCH;
                np->flow_label = 0;
                inet6_clear_bit(REPFLOW, sk);
                return 0;
        }

        spin_lock_bh(&ip6_sk_fl_lock);
        for (sflp = &inet_sk(sk)->ipv6_fl_list;
             (sfl = socklist_dereference(*sflp)) != NULL;
             sflp = &sfl->next) {
                if (sfl->fl->label == freq->flr_label)
                        goto found;
        }
        spin_unlock_bh(&ip6_sk_fl_lock);
        return -ESRCH;
found:
        if (freq->flr_label == (np->flow_label & IPV6_FLOWLABEL_MASK))
                np->flow_label &= ~IPV6_FLOWLABEL_MASK;
        *sflp = sfl->next;
        spin_unlock_bh(&ip6_sk_fl_lock);
        fl_release(sfl->fl);
        kfree_rcu(sfl, rcu);
        return 0;
}

static int ipv6_flowlabel_renew(struct sock *sk, struct in6_flowlabel_req *freq)
{
        struct net *net = sock_net(sk);
        struct ipv6_fl_socklist *sfl;
        int err;

        rcu_read_lock();
        for_each_sk_fl_rcu(sk, sfl) {
                if (sfl->fl->label == freq->flr_label) {
                        err = fl6_renew(sfl->fl, freq->flr_linger,
                                        freq->flr_expires);
                        rcu_read_unlock();
                        return err;
                }
        }
        rcu_read_unlock();

        if (freq->flr_share == IPV6_FL_S_NONE &&
            ns_capable(net->user_ns, CAP_NET_ADMIN)) {
                struct ip6_flowlabel *fl = fl_lookup(net, freq->flr_label);

                if (fl) {
                        err = fl6_renew(fl, freq->flr_linger,
                                        freq->flr_expires);
                        fl_release(fl);
                        return err;
                }
        }
        return -ESRCH;
}

static int ipv6_flowlabel_get(struct sock *sk, struct in6_flowlabel_req *freq,
                sockptr_t optval, int optlen)
{
        struct ipv6_fl_socklist *sfl, *sfl1 = NULL;
        struct ip6_flowlabel *fl, *fl1 = NULL;
        struct net *net = sock_net(sk);
        int err;

        if (freq->flr_flags & IPV6_FL_F_REFLECT) {
                if (net->ipv6.sysctl.flowlabel_consistency) {
                        net_info_ratelimited("Can not set IPV6_FL_F_REFLECT if flowlabel_consistency sysctl is enable\n");
                        return -EPERM;
                }

                if (sk->sk_protocol != IPPROTO_TCP)
                        return -ENOPROTOOPT;
                inet6_set_bit(REPFLOW, sk);
                return 0;
        }

        if (freq->flr_label & ~IPV6_FLOWLABEL_MASK)
                return -EINVAL;
        if (net->ipv6.sysctl.flowlabel_state_ranges &&
            (freq->flr_label & IPV6_FLOWLABEL_STATELESS_FLAG))
                return -ERANGE;

        fl = fl_create(net, sk, freq, optval, optlen, &err);
        if (!fl)
                return err;

        sfl1 = kmalloc_obj(*sfl1);

        if (freq->flr_label) {
                err = -EEXIST;
                rcu_read_lock();
                for_each_sk_fl_rcu(sk, sfl) {
                        if (sfl->fl->label == freq->flr_label) {
                                if (freq->flr_flags & IPV6_FL_F_EXCL) {
                                        rcu_read_unlock();
                                        goto done;
                                }
                                fl1 = sfl->fl;
                                if (!atomic_inc_not_zero(&fl1->users))
                                        fl1 = NULL;
                                break;
                        }
                }
                rcu_read_unlock();

                if (!fl1)
                        fl1 = fl_lookup(net, freq->flr_label);
                if (fl1) {
recheck:
                        err = -EEXIST;
                        if (freq->flr_flags&IPV6_FL_F_EXCL)
                                goto release;
                        err = -EPERM;
                        if (fl1->share == IPV6_FL_S_EXCL ||
                            fl1->share != fl->share ||
                            ((fl1->share == IPV6_FL_S_PROCESS) &&
                             (fl1->owner.pid != fl->owner.pid)) ||
                            ((fl1->share == IPV6_FL_S_USER) &&
                             !uid_eq(fl1->owner.uid, fl->owner.uid)))
                                goto release;

                        err = -ENOMEM;
                        if (!sfl1)
                                goto release;
                        if (fl->linger > fl1->linger)
                                fl1->linger = fl->linger;
                        if ((long)(fl->expires - fl1->expires) > 0)
                                fl1->expires = fl->expires;
                        fl_link(sk, sfl1, fl1);
                        fl_free(fl);
                        return 0;

release:
                        fl_release(fl1);
                        goto done;
                }
        }
        err = -ENOENT;
        if (!(freq->flr_flags & IPV6_FL_F_CREATE))
                goto done;

        err = -ENOMEM;
        if (!sfl1)
                goto done;

        err = mem_check(sk);
        if (err != 0)
                goto done;

        fl1 = fl_intern(net, fl, freq->flr_label);
        if (fl1)
                goto recheck;

        if (!freq->flr_label) {
                size_t offset = offsetof(struct in6_flowlabel_req, flr_label);

                if (copy_to_sockptr_offset(optval, offset, &fl->label,
                                sizeof(fl->label))) {
                        /* Intentionally ignore fault. */
                }
        }

        fl_link(sk, sfl1, fl);
        return 0;
done:
        fl_free(fl);
        kfree(sfl1);
        return err;
}

int ipv6_flowlabel_opt(struct sock *sk, sockptr_t optval, int optlen)
{
        struct in6_flowlabel_req freq;

        if (optlen < sizeof(freq))
                return -EINVAL;
        if (copy_from_sockptr(&freq, optval, sizeof(freq)))
                return -EFAULT;

        switch (freq.flr_action) {
        case IPV6_FL_A_PUT:
                return ipv6_flowlabel_put(sk, &freq);
        case IPV6_FL_A_RENEW:
                return ipv6_flowlabel_renew(sk, &freq);
        case IPV6_FL_A_GET:
                return ipv6_flowlabel_get(sk, &freq, optval, optlen);
        default:
                return -EINVAL;
        }
}

#ifdef CONFIG_PROC_FS

struct ip6fl_iter_state {
        struct seq_net_private p;
        struct pid_namespace *pid_ns;
        int bucket;
};

#define ip6fl_seq_private(seq)  ((struct ip6fl_iter_state *)(seq)->private)

static struct ip6_flowlabel *ip6fl_get_first(struct seq_file *seq)
{
        struct ip6_flowlabel *fl = NULL;
        struct ip6fl_iter_state *state = ip6fl_seq_private(seq);
        struct net *net = seq_file_net(seq);

        for (state->bucket = 0; state->bucket <= FL_HASH_MASK; ++state->bucket) {
                for_each_fl_rcu(state->bucket, fl) {
                        if (net_eq(fl->fl_net, net))
                                goto out;
                }
        }
        fl = NULL;
out:
        return fl;
}

static struct ip6_flowlabel *ip6fl_get_next(struct seq_file *seq, struct ip6_flowlabel *fl)
{
        struct ip6fl_iter_state *state = ip6fl_seq_private(seq);
        struct net *net = seq_file_net(seq);

        for_each_fl_continue_rcu(fl) {
                if (net_eq(fl->fl_net, net))
                        goto out;
        }

try_again:
        if (++state->bucket <= FL_HASH_MASK) {
                for_each_fl_rcu(state->bucket, fl) {
                        if (net_eq(fl->fl_net, net))
                                goto out;
                }
                goto try_again;
        }
        fl = NULL;

out:
        return fl;
}

static struct ip6_flowlabel *ip6fl_get_idx(struct seq_file *seq, loff_t pos)
{
        struct ip6_flowlabel *fl = ip6fl_get_first(seq);
        if (fl)
                while (pos && (fl = ip6fl_get_next(seq, fl)) != NULL)
                        --pos;
        return pos ? NULL : fl;
}

static void *ip6fl_seq_start(struct seq_file *seq, loff_t *pos)
        __acquires(RCU)
{
        struct ip6fl_iter_state *state = ip6fl_seq_private(seq);

        state->pid_ns = proc_pid_ns(file_inode(seq->file)->i_sb);

        rcu_read_lock();
        return *pos ? ip6fl_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
}

static void *ip6fl_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        struct ip6_flowlabel *fl;

        if (v == SEQ_START_TOKEN)
                fl = ip6fl_get_first(seq);
        else
                fl = ip6fl_get_next(seq, v);
        ++*pos;
        return fl;
}

static void ip6fl_seq_stop(struct seq_file *seq, void *v)
        __releases(RCU)
{
        rcu_read_unlock();
}

static int ip6fl_seq_show(struct seq_file *seq, void *v)
{
        struct ip6fl_iter_state *state = ip6fl_seq_private(seq);
        if (v == SEQ_START_TOKEN) {
                seq_puts(seq, "Label S Owner  Users  Linger Expires  Dst                              Opt\n");
        } else {
                struct ip6_flowlabel *fl = v;
                seq_printf(seq,
                           "%05X %-1d %-6d %-6d %-6ld %-8ld %pi6 %-4d\n",
                           (unsigned int)ntohl(fl->label),
                           fl->share,
                           ((fl->share == IPV6_FL_S_PROCESS) ?
                            pid_nr_ns(fl->owner.pid, state->pid_ns) :
                            ((fl->share == IPV6_FL_S_USER) ?
                             from_kuid_munged(seq_user_ns(seq), fl->owner.uid) :
                             0)),
                           atomic_read(&fl->users),
                           fl->linger/HZ,
                           (long)(fl->expires - jiffies)/HZ,
                           &fl->dst,
                           fl->opt ? fl->opt->opt_nflen : 0);
        }
        return 0;
}

static const struct seq_operations ip6fl_seq_ops = {
        .start  =       ip6fl_seq_start,
        .next   =       ip6fl_seq_next,
        .stop   =       ip6fl_seq_stop,
        .show   =       ip6fl_seq_show,
};

static int __net_init ip6_flowlabel_proc_init(struct net *net)
{
        if (!proc_create_net("ip6_flowlabel", 0444, net->proc_net,
                        &ip6fl_seq_ops, sizeof(struct ip6fl_iter_state)))
                return -ENOMEM;
        return 0;
}

static void __net_exit ip6_flowlabel_proc_fini(struct net *net)
{
        remove_proc_entry("ip6_flowlabel", net->proc_net);
}
#else
static inline int ip6_flowlabel_proc_init(struct net *net)
{
        return 0;
}
static inline void ip6_flowlabel_proc_fini(struct net *net)
{
}
#endif

static void __net_exit ip6_flowlabel_net_exit(struct net *net)
{
        ip6_fl_purge(net);
        ip6_flowlabel_proc_fini(net);
}

static struct pernet_operations ip6_flowlabel_net_ops = {
        .init = ip6_flowlabel_proc_init,
        .exit = ip6_flowlabel_net_exit,
};

int ip6_flowlabel_init(void)
{
        return register_pernet_subsys(&ip6_flowlabel_net_ops);
}

void ip6_flowlabel_cleanup(void)
{
        static_key_deferred_flush(&ipv6_flowlabel_exclusive);
        timer_delete(&ip6_fl_gc_timer);
        unregister_pernet_subsys(&ip6_flowlabel_net_ops);
}