/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              Generic socket support routines. Memory allocators, socket lock/release
 *              handler for protocols to use and generic option handler.
 *
 *
 * Authors:     Ross Biro
 *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *              Florian La Roche, <flla@stud.uni-sb.de>
 *              Alan Cox, <A.Cox@swansea.ac.uk>
 *
 * Fixes:
 *              Alan Cox        :       Numerous verify_area() problems
 *              Alan Cox        :       Connecting on a connecting socket
 *                                      now returns an error for tcp.
 *              Alan Cox        :       sock->protocol is set correctly.
 *                                      and is not sometimes left as 0.
 *              Alan Cox        :       connect handles icmp errors on a
 *                                      connect properly. Unfortunately there
 *                                      is a restart syscall nasty there. I
 *                                      can't match BSD without hacking the C
 *                                      library. Ideas urgently sought!
 *              Alan Cox        :       Disallow bind() to addresses that are
 *                                      not ours - especially broadcast ones!!
 *              Alan Cox        :       Socket 1024 _IS_ ok for users. (fencepost)
 *              Alan Cox        :       sock_wfree/sock_rfree don't destroy sockets,
 *                                      instead they leave that for the DESTROY timer.
 *              Alan Cox        :       Clean up error flag in accept
 *              Alan Cox        :       TCP ack handling is buggy, the DESTROY timer
 *                                      was buggy. Put a remove_sock() in the handler
 *                                      for memory when we hit 0. Also altered the timer
 *                                      code. The ACK stuff can wait and needs major
 *                                      TCP layer surgery.
 *              Alan Cox        :       Fixed TCP ack bug, removed remove sock
 *                                      and fixed timer/inet_bh race.
 *              Alan Cox        :       Added zapped flag for TCP
 *              Alan Cox        :       Move kfree_skb into skbuff.c and tidied up surplus code
 *              Alan Cox        :       for new sk_buff allocations wmalloc/rmalloc now call alloc_skb
 *              Alan Cox        :       kfree_s calls now are kfree_skbmem so we can track skb resources
 *              Alan Cox        :       Supports socket option broadcast now as does udp. Packet and raw need fixing.
 *              Alan Cox        :       Added RCVBUF,SNDBUF size setting. It suddenly occurred to me how easy it was so...
 *              Rick Sladkey    :       Relaxed UDP rules for matching packets.
 *              C.E.Hawkins     :       IFF_PROMISC/SIOCGHWADDR support
 *      Pauline Middelink       :       identd support
 *              Alan Cox        :       Fixed connect() taking signals I think.
 *              Alan Cox        :       SO_LINGER supported
 *              Alan Cox        :       Error reporting fixes
 *              Anonymous       :       inet_create tidied up (sk->reuse setting)
 *              Alan Cox        :       inet sockets don't set sk->type!
 *              Alan Cox        :       Split socket option code
 *              Alan Cox        :       Callbacks
 *              Alan Cox        :       Nagle flag for Charles & Johannes stuff
 *              Alex            :       Removed restriction on inet fioctl
 *              Alan Cox        :       Splitting INET from NET core
 *              Alan Cox        :       Fixed bogus SO_TYPE handling in getsockopt()
 *              Adam Caldwell   :       Missing return in SO_DONTROUTE/SO_DEBUG code
 *              Alan Cox        :       Split IP from generic code
 *              Alan Cox        :       New kfree_skbmem()
 *              Alan Cox        :       Make SO_DEBUG superuser only.
 *              Alan Cox        :       Allow anyone to clear SO_DEBUG
 *                                      (compatibility fix)
 *              Alan Cox        :       Added optimistic memory grabbing for AF_UNIX throughput.
 *              Alan Cox        :       Allocator for a socket is settable.
 *              Alan Cox        :       SO_ERROR includes soft errors.
 *              Alan Cox        :       Allow NULL arguments on some SO_ opts
 *              Alan Cox        :       Generic socket allocation to make hooks
 *                                      easier (suggested by Craig Metz).
 *              Michael Pall    :       SO_ERROR returns positive errno again
 *              Steve Whitehouse:       Added default destructor to free
 *                                      protocol private data.
 *              Steve Whitehouse:       Added various other default routines
 *                                      common to several socket families.
 *              Chris Evans     :       Call suser() check last on F_SETOWN
 *              Jay Schulist    :       Added SO_ATTACH_FILTER and SO_DETACH_FILTER.
 *              Andi Kleen      :       Add sock_kmalloc()/sock_kfree_s()
 *              Andi Kleen      :       Fix write_space callback
 *              Chris Evans     :       Security fixes - signedness again
 *              Arnaldo C. Melo :       cleanups, use skb_queue_purge
 *
 * To Fix:
 *
 *
 *              This program is free software; you can redistribute it and/or
 *              modify it under the terms of the GNU General Public License
 *              as published by the Free Software Foundation; either version
 *              2 of the License, or (at your option) any later version.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/errqueue.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/poll.h>
#include <linux/tcp.h>
#include <linux/init.h>
#include <linux/highmem.h>
#include <linux/user_namespace.h>
#include <linux/static_key.h>
#include <linux/memcontrol.h>
#include <linux/prefetch.h>

#include <asm/uaccess.h>

#include <linux/netdevice.h>
#include <net/protocol.h>
#include <linux/skbuff.h>
#include <net/net_namespace.h>
#include <net/request_sock.h>
#include <net/sock.h>
#include <linux/net_tstamp.h>
#include <net/xfrm.h>
#include <linux/ipsec.h>
#include <net/cls_cgroup.h>
#include <net/netprio_cgroup.h>

#include <linux/filter.h>

#include <trace/events/sock.h>

#ifdef CONFIG_INET
#include <net/tcp.h>
#endif

#include <net/busy_poll.h>

static DEFINE_MUTEX(proto_list_mutex);
static LIST_HEAD(proto_list);

#ifdef CONFIG_MEMCG_KMEM
int mem_cgroup_sockets_init(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
{
        struct proto *proto;
        int ret = 0;

        mutex_lock(&proto_list_mutex);
        list_for_each_entry(proto, &proto_list, node) {
                if (proto->init_cgroup) {
                        ret = proto->init_cgroup(memcg, ss);
                        if (ret)
                                goto out;
                }
        }

        mutex_unlock(&proto_list_mutex);
        return ret;
out:
        list_for_each_entry_continue_reverse(proto, &proto_list, node)
                if (proto->destroy_cgroup)
                        proto->destroy_cgroup(memcg);
        mutex_unlock(&proto_list_mutex);
        return ret;
}

void mem_cgroup_sockets_destroy(struct mem_cgroup *memcg)
{
        struct proto *proto;

        mutex_lock(&proto_list_mutex);
        list_for_each_entry_reverse(proto, &proto_list, node)
                if (proto->destroy_cgroup)
                        proto->destroy_cgroup(memcg);
        mutex_unlock(&proto_list_mutex);
}
#endif

/*
 * Each address family might have different locking rules, so we have
 * one slock key per address family:
 */
static struct lock_class_key af_family_keys[AF_MAX];
static struct lock_class_key af_family_slock_keys[AF_MAX];

#if defined(CONFIG_MEMCG_KMEM)
struct static_key memcg_socket_limit_enabled;
EXPORT_SYMBOL(memcg_socket_limit_enabled);
#endif

/*
 * Make lock validator output more readable. (we pre-construct these
 * strings build-time, so that runtime initialization of socket
 * locks is fast):
 */
static const char *const af_family_key_strings[AF_MAX+1] = {
  "sk_lock-AF_UNSPEC", "sk_lock-AF_UNIX"     , "sk_lock-AF_INET"     ,
  "sk_lock-AF_AX25"  , "sk_lock-AF_IPX"      , "sk_lock-AF_APPLETALK",
  "sk_lock-AF_NETROM", "sk_lock-AF_BRIDGE"   , "sk_lock-AF_ATMPVC"   ,
  "sk_lock-AF_X25"   , "sk_lock-AF_INET6"    , "sk_lock-AF_ROSE"     ,
  "sk_lock-AF_DECnet", "sk_lock-AF_NETBEUI"  , "sk_lock-AF_SECURITY" ,
  "sk_lock-AF_KEY"   , "sk_lock-AF_NETLINK"  , "sk_lock-AF_PACKET"   ,
  "sk_lock-AF_ASH"   , "sk_lock-AF_ECONET"   , "sk_lock-AF_ATMSVC"   ,
  "sk_lock-AF_RDS"   , "sk_lock-AF_SNA"      , "sk_lock-AF_IRDA"     ,
  "sk_lock-AF_PPPOX" , "sk_lock-AF_WANPIPE"  , "sk_lock-AF_LLC"      ,
  "sk_lock-27"       , "sk_lock-28"          , "sk_lock-AF_CAN"      ,
  "sk_lock-AF_TIPC"  , "sk_lock-AF_BLUETOOTH", "sk_lock-IUCV"        ,
  "sk_lock-AF_RXRPC" , "sk_lock-AF_ISDN"     , "sk_lock-AF_PHONET"   ,
  "sk_lock-AF_IEEE802154", "sk_lock-AF_CAIF" , "sk_lock-AF_ALG"      ,
  "sk_lock-AF_NFC"   , "sk_lock-AF_VSOCK"    , "sk_lock-AF_MAX"
};
static const char *const af_family_slock_key_strings[AF_MAX+1] = {
  "slock-AF_UNSPEC", "slock-AF_UNIX"     , "slock-AF_INET"     ,
  "slock-AF_AX25"  , "slock-AF_IPX"      , "slock-AF_APPLETALK",
  "slock-AF_NETROM", "slock-AF_BRIDGE"   , "slock-AF_ATMPVC"   ,
  "slock-AF_X25"   , "slock-AF_INET6"    , "slock-AF_ROSE"     ,
  "slock-AF_DECnet", "slock-AF_NETBEUI"  , "slock-AF_SECURITY" ,
  "slock-AF_KEY"   , "slock-AF_NETLINK"  , "slock-AF_PACKET"   ,
  "slock-AF_ASH"   , "slock-AF_ECONET"   , "slock-AF_ATMSVC"   ,
  "slock-AF_RDS"   , "slock-AF_SNA"      , "slock-AF_IRDA"     ,
  "slock-AF_PPPOX" , "slock-AF_WANPIPE"  , "slock-AF_LLC"      ,
  "slock-27"       , "slock-28"          , "slock-AF_CAN"      ,
  "slock-AF_TIPC"  , "slock-AF_BLUETOOTH", "slock-AF_IUCV"     ,
  "slock-AF_RXRPC" , "slock-AF_ISDN"     , "slock-AF_PHONET"   ,
  "slock-AF_IEEE802154", "slock-AF_CAIF" , "slock-AF_ALG"      ,
  "slock-AF_NFC"   , "slock-AF_VSOCK"    ,"slock-AF_MAX"
};
static const char *const af_family_clock_key_strings[AF_MAX+1] = {
  "clock-AF_UNSPEC", "clock-AF_UNIX"     , "clock-AF_INET"     ,
  "clock-AF_AX25"  , "clock-AF_IPX"      , "clock-AF_APPLETALK",
  "clock-AF_NETROM", "clock-AF_BRIDGE"   , "clock-AF_ATMPVC"   ,
  "clock-AF_X25"   , "clock-AF_INET6"    , "clock-AF_ROSE"     ,
  "clock-AF_DECnet", "clock-AF_NETBEUI"  , "clock-AF_SECURITY" ,
  "clock-AF_KEY"   , "clock-AF_NETLINK"  , "clock-AF_PACKET"   ,
  "clock-AF_ASH"   , "clock-AF_ECONET"   , "clock-AF_ATMSVC"   ,
  "clock-AF_RDS"   , "clock-AF_SNA"      , "clock-AF_IRDA"     ,
  "clock-AF_PPPOX" , "clock-AF_WANPIPE"  , "clock-AF_LLC"      ,
  "clock-27"       , "clock-28"          , "clock-AF_CAN"      ,
  "clock-AF_TIPC"  , "clock-AF_BLUETOOTH", "clock-AF_IUCV"     ,
  "clock-AF_RXRPC" , "clock-AF_ISDN"     , "clock-AF_PHONET"   ,
  "clock-AF_IEEE802154", "clock-AF_CAIF" , "clock-AF_ALG"      ,
  "clock-AF_NFC"   , "clock-AF_VSOCK"    , "clock-AF_MAX"
};

/*
 * sk_callback_lock locking rules are per-address-family,
 * so split the lock classes by using a per-AF key:
 */
static struct lock_class_key af_callback_keys[AF_MAX];

/* Take into consideration the size of the struct sk_buff overhead in the
 * determination of these values, since that is non-constant across
 * platforms.  This makes socket queueing behavior and performance
 * not depend upon such differences.
 */
#define _SK_MEM_PACKETS         256
#define _SK_MEM_OVERHEAD        SKB_TRUESIZE(256)
#define SK_WMEM_MAX             (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS)
#define SK_RMEM_MAX             (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS)

/* Run time adjustable parameters. */
__u32 sysctl_wmem_max __read_mostly = SK_WMEM_MAX;
EXPORT_SYMBOL(sysctl_wmem_max);
__u32 sysctl_rmem_max __read_mostly = SK_RMEM_MAX;
EXPORT_SYMBOL(sysctl_rmem_max);
__u32 sysctl_wmem_default __read_mostly = SK_WMEM_MAX;
__u32 sysctl_rmem_default __read_mostly = SK_RMEM_MAX;

/* Maximal space eaten by iovec or ancillary data plus some space */
int sysctl_optmem_max __read_mostly = sizeof(unsigned long)*(2*UIO_MAXIOV+512);
EXPORT_SYMBOL(sysctl_optmem_max);

struct static_key memalloc_socks = STATIC_KEY_INIT_FALSE;
EXPORT_SYMBOL_GPL(memalloc_socks);

/**
 * sk_set_memalloc - sets %SOCK_MEMALLOC
 * @sk: socket to set it on
 *
 * Set %SOCK_MEMALLOC on a socket for access to emergency reserves.
 * It's the responsibility of the admin to adjust min_free_kbytes
 * to meet the requirements
 */
void sk_set_memalloc(struct sock *sk)
{
        sock_set_flag(sk, SOCK_MEMALLOC);
        sk->sk_allocation |= __GFP_MEMALLOC;
        static_key_slow_inc(&memalloc_socks);
}
EXPORT_SYMBOL_GPL(sk_set_memalloc);

void sk_clear_memalloc(struct sock *sk)
{
        sock_reset_flag(sk, SOCK_MEMALLOC);
        sk->sk_allocation &= ~__GFP_MEMALLOC;
        static_key_slow_dec(&memalloc_socks);

        /*
         * SOCK_MEMALLOC is allowed to ignore rmem limits to ensure forward
         * progress of swapping. However, if SOCK_MEMALLOC is cleared while
         * it has rmem allocations there is a risk that the user of the
         * socket cannot make forward progress due to exceeding the rmem
         * limits. By rights, sk_clear_memalloc() should only be called
         * on sockets being torn down but warn and reset the accounting if
         * that assumption breaks.
         */
        if (WARN_ON(sk->sk_forward_alloc))
                sk_mem_reclaim(sk);
}
EXPORT_SYMBOL_GPL(sk_clear_memalloc);

int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
        int ret;
        unsigned long pflags = current->flags;

        /* these should have been dropped before queueing */
        BUG_ON(!sock_flag(sk, SOCK_MEMALLOC));

        current->flags |= PF_MEMALLOC;
        ret = sk->sk_backlog_rcv(sk, skb);
        tsk_restore_flags(current, pflags, PF_MEMALLOC);

        return ret;
}
EXPORT_SYMBOL(__sk_backlog_rcv);

static int sock_set_timeout(long *timeo_p, char __user *optval, int optlen)
{
        struct timeval tv;

        if (optlen < sizeof(tv))
                return -EINVAL;
        if (copy_from_user(&tv, optval, sizeof(tv)))
                return -EFAULT;
        if (tv.tv_usec < 0 || tv.tv_usec >= USEC_PER_SEC)
                return -EDOM;

        if (tv.tv_sec < 0) {
                static int warned __read_mostly;

                *timeo_p = 0;
                if (warned < 10 && net_ratelimit()) {
                        warned++;
                        pr_info("%s: `%s' (pid %d) tries to set negative timeout\n",
                                __func__, current->comm, task_pid_nr(current));
                }
                return 0;
        }
        *timeo_p = MAX_SCHEDULE_TIMEOUT;
        if (tv.tv_sec == 0 && tv.tv_usec == 0)
                return 0;
        if (tv.tv_sec < (MAX_SCHEDULE_TIMEOUT/HZ - 1))
                *timeo_p = tv.tv_sec*HZ + (tv.tv_usec+(1000000/HZ-1))/(1000000/HZ);
        return 0;
}

static void sock_warn_obsolete_bsdism(const char *name)
{
        static int warned;
        static char warncomm[TASK_COMM_LEN];
        if (strcmp(warncomm, current->comm) && warned < 5) {
                strcpy(warncomm,  current->comm);
                pr_warn("process `%s' is using obsolete %s SO_BSDCOMPAT\n",
                        warncomm, name);
                warned++;
        }
}

#define SK_FLAGS_TIMESTAMP ((1UL << SOCK_TIMESTAMP) | (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE))

static void sock_disable_timestamp(struct sock *sk, unsigned long flags)
{
        if (sk->sk_flags & flags) {
                sk->sk_flags &= ~flags;
                if (!(sk->sk_flags & SK_FLAGS_TIMESTAMP))
                        net_disable_timestamp();
        }
}


int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
{
        int err;
        int skb_len;
        unsigned long flags;
        struct sk_buff_head *list = &sk->sk_receive_queue;

        if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf) {
                atomic_inc(&sk->sk_drops);
                trace_sock_rcvqueue_full(sk, skb);
                return -ENOMEM;
        }

        err = sk_filter(sk, skb);
        if (err)
                return err;

        if (!sk_rmem_schedule(sk, skb, skb->truesize)) {
                atomic_inc(&sk->sk_drops);
                return -ENOBUFS;
        }

        skb->dev = NULL;
        skb_set_owner_r(skb, sk);

        /* Cache the SKB length before we tack it onto the receive
         * queue.  Once it is added it no longer belongs to us and
         * may be freed by other threads of control pulling packets
         * from the queue.
         */
        skb_len = skb->len;

        /* we escape from rcu protected region, make sure we dont leak
         * a norefcounted dst
         */
        skb_dst_force(skb);

        spin_lock_irqsave(&list->lock, flags);
        skb->dropcount = atomic_read(&sk->sk_drops);
        __skb_queue_tail(list, skb);
        spin_unlock_irqrestore(&list->lock, flags);

        if (!sock_flag(sk, SOCK_DEAD))
                sk->sk_data_ready(sk, skb_len);
        return 0;
}
EXPORT_SYMBOL(sock_queue_rcv_skb);

int sk_receive_skb(struct sock *sk, struct sk_buff *skb, const int nested)
{
        int rc = NET_RX_SUCCESS;

        if (sk_filter(sk, skb))
                goto discard_and_relse;

        skb->dev = NULL;

        if (sk_rcvqueues_full(sk, skb, sk->sk_rcvbuf)) {
                atomic_inc(&sk->sk_drops);
                goto discard_and_relse;
        }
        if (nested)
                bh_lock_sock_nested(sk);
        else
                bh_lock_sock(sk);
        if (!sock_owned_by_user(sk)) {
                /*
                 * trylock + unlock semantics:
                 */
                mutex_acquire(&sk->sk_lock.dep_map, 0, 1, _RET_IP_);

                rc = sk_backlog_rcv(sk, skb);

                mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_);
        } else if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) {
                bh_unlock_sock(sk);
                atomic_inc(&sk->sk_drops);
                goto discard_and_relse;
        }

        bh_unlock_sock(sk);
out:
        sock_put(sk);
        return rc;
discard_and_relse:
        kfree_skb(skb);
        goto out;
}
EXPORT_SYMBOL(sk_receive_skb);

void sk_reset_txq(struct sock *sk)
{
        sk_tx_queue_clear(sk);
}
EXPORT_SYMBOL(sk_reset_txq);

struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie)
{
        struct dst_entry *dst = __sk_dst_get(sk);

        if (dst && dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
                sk_tx_queue_clear(sk);
                RCU_INIT_POINTER(sk->sk_dst_cache, NULL);
                dst_release(dst);
                return NULL;
        }

        return dst;
}
EXPORT_SYMBOL(__sk_dst_check);

struct dst_entry *sk_dst_check(struct sock *sk, u32 cookie)
{
        struct dst_entry *dst = sk_dst_get(sk);

        if (dst && dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
                sk_dst_reset(sk);
                dst_release(dst);
                return NULL;
        }

        return dst;
}
EXPORT_SYMBOL(sk_dst_check);

static int sock_setbindtodevice(struct sock *sk, char __user *optval,
                                int optlen)
{
        int ret = -ENOPROTOOPT;
#ifdef CONFIG_NETDEVICES
        struct net *net = sock_net(sk);
        char devname[IFNAMSIZ];
        int index;

        /* Sorry... */
        ret = -EPERM;
        if (!ns_capable(net->user_ns, CAP_NET_RAW))
                goto out;

        ret = -EINVAL;
        if (optlen < 0)
                goto out;

        /* Bind this socket to a particular device like "eth0",
         * as specified in the passed interface name. If the
         * name is "" or the option length is zero the socket
         * is not bound.
         */
        if (optlen > IFNAMSIZ - 1)
                optlen = IFNAMSIZ - 1;
        memset(devname, 0, sizeof(devname));

        ret = -EFAULT;
        if (copy_from_user(devname, optval, optlen))
                goto out;

        index = 0;
        if (devname[0] != '\0') {
                struct net_device *dev;

                rcu_read_lock();
                dev = dev_get_by_name_rcu(net, devname);
                if (dev)
                        index = dev->ifindex;
                rcu_read_unlock();
                ret = -ENODEV;
                if (!dev)
                        goto out;
        }

        lock_sock(sk);
        sk->sk_bound_dev_if = index;
        sk_dst_reset(sk);
        release_sock(sk);

        ret = 0;

out:
#endif

        return ret;
}

static int sock_getbindtodevice(struct sock *sk, char __user *optval,
                                int __user *optlen, int len)
{
        int ret = -ENOPROTOOPT;
#ifdef CONFIG_NETDEVICES
        struct net *net = sock_net(sk);
        char devname[IFNAMSIZ];

        if (sk->sk_bound_dev_if == 0) {
                len = 0;
                goto zero;
        }

        ret = -EINVAL;
        if (len < IFNAMSIZ)
                goto out;

        ret = netdev_get_name(net, devname, sk->sk_bound_dev_if);
        if (ret)
                goto out;

        len = strlen(devname) + 1;

        ret = -EFAULT;
        if (copy_to_user(optval, devname, len))
                goto out;

zero:
        ret = -EFAULT;
        if (put_user(len, optlen))
                goto out;

        ret = 0;

out:
#endif

        return ret;
}

static inline void sock_valbool_flag(struct sock *sk, int bit, int valbool)
{
        if (valbool)
                sock_set_flag(sk, bit);
        else
                sock_reset_flag(sk, bit);
}

/*
 *      This is meant for all protocols to use and covers goings on
 *      at the socket level. Everything here is generic.
 */

int sock_setsockopt(struct socket *sock, int level, int optname,
                    char __user *optval, unsigned int optlen)
{
        struct sock *sk = sock->sk;
        int val;
        int valbool;
        struct linger ling;
        int ret = 0;

        /*
         *      Options without arguments
         */

        if (optname == SO_BINDTODEVICE)
                return sock_setbindtodevice(sk, optval, optlen);

        if (optlen < sizeof(int))
                return -EINVAL;

        if (get_user(val, (int __user *)optval))
                return -EFAULT;

        valbool = val ? 1 : 0;

        lock_sock(sk);

        switch (optname) {
        case SO_DEBUG:
                if (val && !capable(CAP_NET_ADMIN))
                        ret = -EACCES;
                else
                        sock_valbool_flag(sk, SOCK_DBG, valbool);
                break;
        case SO_REUSEADDR:
                sk->sk_reuse = (valbool ? SK_CAN_REUSE : SK_NO_REUSE);
                break;
        case SO_REUSEPORT:
                sk->sk_reuseport = valbool;
                break;
        case SO_TYPE:
        case SO_PROTOCOL:
        case SO_DOMAIN:
        case SO_ERROR:
                ret = -ENOPROTOOPT;
                break;
        case SO_DONTROUTE:
                sock_valbool_flag(sk, SOCK_LOCALROUTE, valbool);
                break;
        case SO_BROADCAST:
                sock_valbool_flag(sk, SOCK_BROADCAST, valbool);
                break;
        case SO_SNDBUF:
                /* Don't error on this BSD doesn't and if you think
                 * about it this is right. Otherwise apps have to
                 * play 'guess the biggest size' games. RCVBUF/SNDBUF
                 * are treated in BSD as hints
                 */
                val = min_t(u32, val, sysctl_wmem_max);
set_sndbuf:
                sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
                sk->sk_sndbuf = max_t(u32, val * 2, SOCK_MIN_SNDBUF);
                /* Wake up sending tasks if we upped the value. */
                sk->sk_write_space(sk);
                break;

        case SO_SNDBUFFORCE:
                if (!capable(CAP_NET_ADMIN)) {
                        ret = -EPERM;
                        break;
                }
                goto set_sndbuf;

        case SO_RCVBUF:
                /* Don't error on this BSD doesn't and if you think
                 * about it this is right. Otherwise apps have to
                 * play 'guess the biggest size' games. RCVBUF/SNDBUF
                 * are treated in BSD as hints
                 */
                val = min_t(u32, val, sysctl_rmem_max);
set_rcvbuf:
                sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
                /*
                 * We double it on the way in to account for
                 * "struct sk_buff" etc. overhead.   Applications
                 * assume that the SO_RCVBUF setting they make will
                 * allow that much actual data to be received on that
                 * socket.
                 *
                 * Applications are unaware that "struct sk_buff" and
                 * other overheads allocate from the receive buffer
                 * during socket buffer allocation.
                 *
                 * And after considering the possible alternatives,
                 * returning the value we actually used in getsockopt
                 * is the most desirable behavior.
                 */
                sk->sk_rcvbuf = max_t(u32, val * 2, SOCK_MIN_RCVBUF);
                break;

        case SO_RCVBUFFORCE:
                if (!capable(CAP_NET_ADMIN)) {
                        ret = -EPERM;
                        break;
                }
                goto set_rcvbuf;

        case SO_KEEPALIVE:
#ifdef CONFIG_INET
                if (sk->sk_protocol == IPPROTO_TCP &&
                    sk->sk_type == SOCK_STREAM)
                        tcp_set_keepalive(sk, valbool);
#endif
                sock_valbool_flag(sk, SOCK_KEEPOPEN, valbool);
                break;

        case SO_OOBINLINE:
                sock_valbool_flag(sk, SOCK_URGINLINE, valbool);
                break;

        case SO_NO_CHECK:
                sk->sk_no_check = valbool;
                break;

        case SO_PRIORITY:
                if ((val >= 0 && val <= 6) ||
                    ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
                        sk->sk_priority = val;
                else
                        ret = -EPERM;
                break;

        case SO_LINGER:
                if (optlen < sizeof(ling)) {
                        ret = -EINVAL;  /* 1003.1g */
                        break;
                }
                if (copy_from_user(&ling, optval, sizeof(ling))) {
                        ret = -EFAULT;
                        break;
                }
                if (!ling.l_onoff)
                        sock_reset_flag(sk, SOCK_LINGER);
                else {
#if (BITS_PER_LONG == 32)
                        if ((unsigned int)ling.l_linger >= MAX_SCHEDULE_TIMEOUT/HZ)
                                sk->sk_lingertime = MAX_SCHEDULE_TIMEOUT;
                        else
#endif
                                sk->sk_lingertime = (unsigned int)ling.l_linger * HZ;
                        sock_set_flag(sk, SOCK_LINGER);
                }
                break;

        case SO_BSDCOMPAT:
                sock_warn_obsolete_bsdism("setsockopt");
                break;

        case SO_PASSCRED:
                if (valbool)
                        set_bit(SOCK_PASSCRED, &sock->flags);
                else
                        clear_bit(SOCK_PASSCRED, &sock->flags);
                break;

        case SO_TIMESTAMP:
        case SO_TIMESTAMPNS:
                if (valbool)  {
                        if (optname == SO_TIMESTAMP)
                                sock_reset_flag(sk, SOCK_RCVTSTAMPNS);
                        else
                                sock_set_flag(sk, SOCK_RCVTSTAMPNS);
                        sock_set_flag(sk, SOCK_RCVTSTAMP);
                        sock_enable_timestamp(sk, SOCK_TIMESTAMP);
                } else {
                        sock_reset_flag(sk, SOCK_RCVTSTAMP);
                        sock_reset_flag(sk, SOCK_RCVTSTAMPNS);
                }
                break;

        case SO_TIMESTAMPING:
                if (val & ~SOF_TIMESTAMPING_MASK) {
                        ret = -EINVAL;
                        break;
                }
                sock_valbool_flag(sk, SOCK_TIMESTAMPING_TX_HARDWARE,
                                  val & SOF_TIMESTAMPING_TX_HARDWARE);
                sock_valbool_flag(sk, SOCK_TIMESTAMPING_TX_SOFTWARE,
                                  val & SOF_TIMESTAMPING_TX_SOFTWARE);
                sock_valbool_flag(sk, SOCK_TIMESTAMPING_RX_HARDWARE,
                                  val & SOF_TIMESTAMPING_RX_HARDWARE);
                if (val & SOF_TIMESTAMPING_RX_SOFTWARE)
                        sock_enable_timestamp(sk,
                                              SOCK_TIMESTAMPING_RX_SOFTWARE);
                else
                        sock_disable_timestamp(sk,
                                               (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE));
                sock_valbool_flag(sk, SOCK_TIMESTAMPING_SOFTWARE,
                                  val & SOF_TIMESTAMPING_SOFTWARE);
                sock_valbool_flag(sk, SOCK_TIMESTAMPING_SYS_HARDWARE,
                                  val & SOF_TIMESTAMPING_SYS_HARDWARE);
                sock_valbool_flag(sk, SOCK_TIMESTAMPING_RAW_HARDWARE,
                                  val & SOF_TIMESTAMPING_RAW_HARDWARE);
                break;

        case SO_RCVLOWAT:
                if (val < 0)
                        val = INT_MAX;
                sk->sk_rcvlowat = val ? : 1;
                break;

        case SO_RCVTIMEO:
                ret = sock_set_timeout(&sk->sk_rcvtimeo, optval, optlen);
                break;

        case SO_SNDTIMEO:
                ret = sock_set_timeout(&sk->sk_sndtimeo, optval, optlen);
                break;

        case SO_ATTACH_FILTER:
                ret = -EINVAL;
                if (optlen == sizeof(struct sock_fprog)) {
                        struct sock_fprog fprog;

                        ret = -EFAULT;
                        if (copy_from_user(&fprog, optval, sizeof(fprog)))
                                break;

                        ret = sk_attach_filter(&fprog, sk);
                }
                break;

        case SO_DETACH_FILTER:
                ret = sk_detach_filter(sk);
                break;

        case SO_LOCK_FILTER:
                if (sock_flag(sk, SOCK_FILTER_LOCKED) && !valbool)
                        ret = -EPERM;
                else
                        sock_valbool_flag(sk, SOCK_FILTER_LOCKED, valbool);
                break;

        case SO_PASSSEC:
                if (valbool)
                        set_bit(SOCK_PASSSEC, &sock->flags);
                else
                        clear_bit(SOCK_PASSSEC, &sock->flags);
                break;
        case SO_MARK:
                if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
                        ret = -EPERM;
                else
                        sk->sk_mark = val;
                break;

                /* We implement the SO_SNDLOWAT etc to
                   not be settable (1003.1g 5.3) */
        case SO_RXQ_OVFL:
                sock_valbool_flag(sk, SOCK_RXQ_OVFL, valbool);
                break;

        case SO_WIFI_STATUS:
                sock_valbool_flag(sk, SOCK_WIFI_STATUS, valbool);
                break;

        case SO_PEEK_OFF:
                if (sock->ops->set_peek_off)
                        sock->ops->set_peek_off(sk, val);
                else
                        ret = -EOPNOTSUPP;
                break;

        case SO_NOFCS:
                sock_valbool_flag(sk, SOCK_NOFCS, valbool);
                break;

        case SO_SELECT_ERR_QUEUE:
                sock_valbool_flag(sk, SOCK_SELECT_ERR_QUEUE, valbool);
                break;

#ifdef CONFIG_NET_RX_BUSY_POLL
        case SO_BUSY_POLL:
                /* allow unprivileged users to decrease the value */
                if ((val > sk->sk_ll_usec) && !capable(CAP_NET_ADMIN))
                        ret = -EPERM;
                else {
                        if (val < 0)
                                ret = -EINVAL;
                        else
                                sk->sk_ll_usec = val;
                }
                break;
#endif
        default:
                ret = -ENOPROTOOPT;
                break;
        }
        release_sock(sk);
        return ret;
}
EXPORT_SYMBOL(sock_setsockopt);


void cred_to_ucred(struct pid *pid, const struct cred *cred,
                   struct ucred *ucred)
{
        ucred->pid = pid_vnr(pid);
        ucred->uid = ucred->gid = -1;
        if (cred) {
                struct user_namespace *current_ns = current_user_ns();

                ucred->uid = from_kuid_munged(current_ns, cred->euid);
                ucred->gid = from_kgid_munged(current_ns, cred->egid);
        }
}
EXPORT_SYMBOL_GPL(cred_to_ucred);

int sock_getsockopt(struct socket *sock, int level, int optname,
                    char __user *optval, int __user *optlen)
{
        struct sock *sk = sock->sk;

        union {
                int val;
                struct linger ling;
                struct timeval tm;
        } v;

        int lv = sizeof(int);
        int len;

        if (get_user(len, optlen))
                return -EFAULT;
        if (len < 0)
                return -EINVAL;

        memset(&v, 0, sizeof(v));

        switch (optname) {
        case SO_DEBUG:
                v.val = sock_flag(sk, SOCK_DBG);
                break;

        case SO_DONTROUTE:
                v.val = sock_flag(sk, SOCK_LOCALROUTE);
                break;

        case SO_BROADCAST:
                v.val = sock_flag(sk, SOCK_BROADCAST);
                break;

        case SO_SNDBUF:
                v.val = sk->sk_sndbuf;
                break;

        case SO_RCVBUF:
                v.val = sk->sk_rcvbuf;
                break;

        case SO_REUSEADDR:
                v.val = sk->sk_reuse;
                break;

        case SO_REUSEPORT:
                v.val = sk->sk_reuseport;
                break;

        case SO_KEEPALIVE:
                v.val = sock_flag(sk, SOCK_KEEPOPEN);
                break;

        case SO_TYPE:
                v.val = sk->sk_type;
                break;

        case SO_PROTOCOL:
                v.val = sk->sk_protocol;

                break;

        case SO_DOMAIN:
                v.val = sk->sk_family;
                break;

        case SO_ERROR:
                v.val = -sock_error(sk);
                if (v.val == 0)
                        v.val = xchg(&sk->sk_err_soft, 0);
                break;

        case SO_OOBINLINE:
                v.val = sock_flag(sk, SOCK_URGINLINE);
                break;

        case SO_NO_CHECK:
                v.val = sk->sk_no_check;
                break;

        case SO_PRIORITY:
                v.val = sk->sk_priority;
                break;

        case SO_LINGER:
                lv              = sizeof(v.ling);
                v.ling.l_onoff  = sock_flag(sk, SOCK_LINGER);
                v.ling.l_linger = sk->sk_lingertime / HZ;
                break;

        case SO_BSDCOMPAT:
                sock_warn_obsolete_bsdism("getsockopt");
                break;

        case SO_TIMESTAMP:
                v.val = sock_flag(sk, SOCK_RCVTSTAMP) &&
                                !sock_flag(sk, SOCK_RCVTSTAMPNS);
                break;

        case SO_TIMESTAMPNS:
                v.val = sock_flag(sk, SOCK_RCVTSTAMPNS);
                break;

        case SO_TIMESTAMPING:
                v.val = 0;
                if (sock_flag(sk, SOCK_TIMESTAMPING_TX_HARDWARE))
                        v.val |= SOF_TIMESTAMPING_TX_HARDWARE;
                if (sock_flag(sk, SOCK_TIMESTAMPING_TX_SOFTWARE))
                        v.val |= SOF_TIMESTAMPING_TX_SOFTWARE;
                if (sock_flag(sk, SOCK_TIMESTAMPING_RX_HARDWARE))
                        v.val |= SOF_TIMESTAMPING_RX_HARDWARE;
                if (sock_flag(sk, SOCK_TIMESTAMPING_RX_SOFTWARE))
                        v.val |= SOF_TIMESTAMPING_RX_SOFTWARE;
                if (sock_flag(sk, SOCK_TIMESTAMPING_SOFTWARE))
                        v.val |= SOF_TIMESTAMPING_SOFTWARE;
                if (sock_flag(sk, SOCK_TIMESTAMPING_SYS_HARDWARE))
                        v.val |= SOF_TIMESTAMPING_SYS_HARDWARE;
                if (sock_flag(sk, SOCK_TIMESTAMPING_RAW_HARDWARE))
                        v.val |= SOF_TIMESTAMPING_RAW_HARDWARE;
                break;

        case SO_RCVTIMEO:
                lv = sizeof(struct timeval);
                if (sk->sk_rcvtimeo == MAX_SCHEDULE_TIMEOUT) {
                        v.tm.tv_sec = 0;
                        v.tm.tv_usec = 0;
                } else {
                        v.tm.tv_sec = sk->sk_rcvtimeo / HZ;
                        v.tm.tv_usec = ((sk->sk_rcvtimeo % HZ) * 1000000) / HZ;
                }
                break;

        case SO_SNDTIMEO:
                lv = sizeof(struct timeval);
                if (sk->sk_sndtimeo == MAX_SCHEDULE_TIMEOUT) {
                        v.tm.tv_sec = 0;
                        v.tm.tv_usec = 0;
                } else {
                        v.tm.tv_sec = sk->sk_sndtimeo / HZ;
                        v.tm.tv_usec = ((sk->sk_sndtimeo % HZ) * 1000000) / HZ;
                }
                break;

        case SO_RCVLOWAT:
                v.val = sk->sk_rcvlowat;
                break;

        case SO_SNDLOWAT:
                v.val = 1;
                break;

        case SO_PASSCRED:
                v.val = !!test_bit(SOCK_PASSCRED, &sock->flags);
                break;

        case SO_PEERCRED:
        {
                struct ucred peercred;
                if (len > sizeof(peercred))
                        len = sizeof(peercred);
                cred_to_ucred(sk->sk_peer_pid, sk->sk_peer_cred, &peercred);
                if (copy_to_user(optval, &peercred, len))
                        return -EFAULT;
                goto lenout;
        }

        case SO_PEERNAME:
        {
                char address[128];

                if (sock->ops->getname(sock, (struct sockaddr *)address, &lv, 2))
                        return -ENOTCONN;
                if (lv < len)
                        return -EINVAL;
                if (copy_to_user(optval, address, len))
                        return -EFAULT;
                goto lenout;
        }

        /* Dubious BSD thing... Probably nobody even uses it, but
         * the UNIX standard wants it for whatever reason... -DaveM
         */
        case SO_ACCEPTCONN:
                v.val = sk->sk_state == TCP_LISTEN;
                break;

        case SO_PASSSEC:
                v.val = !!test_bit(SOCK_PASSSEC, &sock->flags);
                break;

        case SO_PEERSEC:
                return security_socket_getpeersec_stream(sock, optval, optlen, len);

        case SO_MARK:
                v.val = sk->sk_mark;
                break;

        case SO_RXQ_OVFL:
                v.val = sock_flag(sk, SOCK_RXQ_OVFL);
                break;

        case SO_WIFI_STATUS:
                v.val = sock_flag(sk, SOCK_WIFI_STATUS);
                break;

        case SO_PEEK_OFF:
                if (!sock->ops->set_peek_off)
                        return -EOPNOTSUPP;

                v.val = sk->sk_peek_off;
                break;
        case SO_NOFCS:
                v.val = sock_flag(sk, SOCK_NOFCS);
                break;

        case SO_BINDTODEVICE:
                return sock_getbindtodevice(sk, optval, optlen, len);

        case SO_GET_FILTER:
                len = sk_get_filter(sk, (struct sock_filter __user *)optval, len);
                if (len < 0)
                        return len;

                goto lenout;

        case SO_LOCK_FILTER:
                v.val = sock_flag(sk, SOCK_FILTER_LOCKED);
                break;

        case SO_SELECT_ERR_QUEUE:
                v.val = sock_flag(sk, SOCK_SELECT_ERR_QUEUE);
                break;

#ifdef CONFIG_NET_RX_BUSY_POLL
        case SO_BUSY_POLL:
                v.val = sk->sk_ll_usec;
                break;
#endif

        default:
                return -ENOPROTOOPT;
        }

        if (len > lv)
                len = lv;
        if (copy_to_user(optval, &v, len))
                return -EFAULT;
lenout:
        if (put_user(len, optlen))
                return -EFAULT;
        return 0;
}

/*
 * Initialize an sk_lock.
 *
 * (We also register the sk_lock with the lock validator.)
 */
static inline void sock_lock_init(struct sock *sk)
{
        sock_lock_init_class_and_name(sk,
                        af_family_slock_key_strings[sk->sk_family],
                        af_family_slock_keys + sk->sk_family,
                        af_family_key_strings[sk->sk_family],
                        af_family_keys + sk->sk_family);
}

/*
 * Copy all fields from osk to nsk but nsk->sk_refcnt must not change yet,
 * even temporarly, because of RCU lookups. sk_node should also be left as is.
 * We must not copy fields between sk_dontcopy_begin and sk_dontcopy_end
 */
static void sock_copy(struct sock *nsk, const struct sock *osk)
{
#ifdef CONFIG_SECURITY_NETWORK
        void *sptr = nsk->sk_security;
#endif
        memcpy(nsk, osk, offsetof(struct sock, sk_dontcopy_begin));

        memcpy(&nsk->sk_dontcopy_end, &osk->sk_dontcopy_end,
               osk->sk_prot->obj_size - offsetof(struct sock, sk_dontcopy_end));

#ifdef CONFIG_SECURITY_NETWORK
        nsk->sk_security = sptr;
        security_sk_clone(osk, nsk);
#endif
}

void sk_prot_clear_portaddr_nulls(struct sock *sk, int size)
{
        unsigned long nulls1, nulls2;

        nulls1 = offsetof(struct sock, __sk_common.skc_node.next);
        nulls2 = offsetof(struct sock, __sk_common.skc_portaddr_node.next);
        if (nulls1 > nulls2)
                swap(nulls1, nulls2);

        if (nulls1 != 0)
                memset((char *)sk, 0, nulls1);
        memset((char *)sk + nulls1 + sizeof(void *), 0,
               nulls2 - nulls1 - sizeof(void *));
        memset((char *)sk + nulls2 + sizeof(void *), 0,
               size - nulls2 - sizeof(void *));
}
EXPORT_SYMBOL(sk_prot_clear_portaddr_nulls);

static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority,
                int family)
{
        struct sock *sk;
        struct kmem_cache *slab;

        slab = prot->slab;
        if (slab != NULL) {
                sk = kmem_cache_alloc(slab, priority & ~__GFP_ZERO);
                if (!sk)
                        return sk;
                if (priority & __GFP_ZERO) {
                        if (prot->clear_sk)
                                prot->clear_sk(sk, prot->obj_size);
                        else
                                sk_prot_clear_nulls(sk, prot->obj_size);
                }
        } else
                sk = kmalloc(prot->obj_size, priority);

        if (sk != NULL) {
                kmemcheck_annotate_bitfield(sk, flags);

                if (security_sk_alloc(sk, family, priority))
                        goto out_free;

                if (!try_module_get(prot->owner))
                        goto out_free_sec;
                sk_tx_queue_clear(sk);
        }

        return sk;

out_free_sec:
        security_sk_free(sk);
out_free:
        if (slab != NULL)
                kmem_cache_free(slab, sk);
        else
                kfree(sk);
        return NULL;
}

static void sk_prot_free(struct proto *prot, struct sock *sk)
{
        struct kmem_cache *slab;
        struct module *owner;

        owner = prot->owner;
        slab = prot->slab;

        security_sk_free(sk);
        if (slab != NULL)
                kmem_cache_free(slab, sk);
        else
                kfree(sk);
        module_put(owner);
}

#if IS_ENABLED(CONFIG_NET_CLS_CGROUP)
void sock_update_classid(struct sock *sk)
{
        u32 classid;

        classid = task_cls_classid(current);
        if (classid != sk->sk_classid)
                sk->sk_classid = classid;
}
EXPORT_SYMBOL(sock_update_classid);
#endif

#if IS_ENABLED(CONFIG_NETPRIO_CGROUP)
void sock_update_netprioidx(struct sock *sk)
{
        if (in_interrupt())
                return;

        sk->sk_cgrp_prioidx = task_netprioidx(current);
}
EXPORT_SYMBOL_GPL(sock_update_netprioidx);
#endif

/**
 *      sk_alloc - All socket objects are allocated here
 *      @net: the applicable net namespace
 *      @family: protocol family
 *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 *      @prot: struct proto associated with this new sock instance
 */
struct sock *sk_alloc(struct net *net, int family, gfp_t priority,
                      struct proto *prot)
{
        struct sock *sk;

        sk = sk_prot_alloc(prot, priority | __GFP_ZERO, family);
        if (sk) {
                sk->sk_family = family;
                /*
                 * See comment in struct sock definition to understand
                 * why we need sk_prot_creator -acme
                 */
                sk->sk_prot = sk->sk_prot_creator = prot;
                sock_lock_init(sk);
                sock_net_set(sk, get_net(net));
                atomic_set(&sk->sk_wmem_alloc, 1);

                sock_update_classid(sk);
                sock_update_netprioidx(sk);
        }

        return sk;
}
EXPORT_SYMBOL(sk_alloc);

static void __sk_free(struct sock *sk)
{
        struct sk_filter *filter;

        if (sk->sk_destruct)
                sk->sk_destruct(sk);

        filter = rcu_dereference_check(sk->sk_filter,
                                       atomic_read(&sk->sk_wmem_alloc) == 0);
        if (filter) {
                sk_filter_uncharge(sk, filter);
                RCU_INIT_POINTER(sk->sk_filter, NULL);
        }

        sock_disable_timestamp(sk, SK_FLAGS_TIMESTAMP);

        if (atomic_read(&sk->sk_omem_alloc))
                pr_debug("%s: optmem leakage (%d bytes) detected\n",
                         __func__, atomic_read(&sk->sk_omem_alloc));

        if (sk->sk_peer_cred)
                put_cred(sk->sk_peer_cred);
        put_pid(sk->sk_peer_pid);
        put_net(sock_net(sk));
        sk_prot_free(sk->sk_prot_creator, sk);
}

void sk_free(struct sock *sk)
{
        /*
         * We subtract one from sk_wmem_alloc and can know if
         * some packets are still in some tx queue.
         * If not null, sock_wfree() will call __sk_free(sk) later
         */
        if (atomic_dec_and_test(&sk->sk_wmem_alloc))
                __sk_free(sk);
}
EXPORT_SYMBOL(sk_free);

/*
 * Last sock_put should drop reference to sk->sk_net. It has already
 * been dropped in sk_change_net. Taking reference to stopping namespace
 * is not an option.
 * Take reference to a socket to remove it from hash _alive_ and after that
 * destroy it in the context of init_net.
 */
void sk_release_kernel(struct sock *sk)
{
        if (sk == NULL || sk->sk_socket == NULL)
                return;

        sock_hold(sk);
        sock_release(sk->sk_socket);
        release_net(sock_net(sk));
        sock_net_set(sk, get_net(&init_net));
        sock_put(sk);
}
EXPORT_SYMBOL(sk_release_kernel);

static void sk_update_clone(const struct sock *sk, struct sock *newsk)
{
        if (mem_cgroup_sockets_enabled && sk->sk_cgrp)
                sock_update_memcg(newsk);
}

/**
 *      sk_clone_lock - clone a socket, and lock its clone
 *      @sk: the socket to clone
 *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 *
 *      Caller must unlock socket even in error path (bh_unlock_sock(newsk))
 */
struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
{
        struct sock *newsk;

        newsk = sk_prot_alloc(sk->sk_prot, priority, sk->sk_family);
        if (newsk != NULL) {
                struct sk_filter *filter;

                sock_copy(newsk, sk);

                /* SANITY */
                get_net(sock_net(newsk));
                sk_node_init(&newsk->sk_node);
                sock_lock_init(newsk);
                bh_lock_sock(newsk);
                newsk->sk_backlog.head  = newsk->sk_backlog.tail = NULL;
                newsk->sk_backlog.len = 0;

                atomic_set(&newsk->sk_rmem_alloc, 0);
                /*
                 * sk_wmem_alloc set to one (see sk_free() and sock_wfree())
                 */
                atomic_set(&newsk->sk_wmem_alloc, 1);
                atomic_set(&newsk->sk_omem_alloc, 0);
                skb_queue_head_init(&newsk->sk_receive_queue);
                skb_queue_head_init(&newsk->sk_write_queue);
#ifdef CONFIG_NET_DMA
                skb_queue_head_init(&newsk->sk_async_wait_queue);
#endif

                spin_lock_init(&newsk->sk_dst_lock);
                rwlock_init(&newsk->sk_callback_lock);
                lockdep_set_class_and_name(&newsk->sk_callback_lock,
                                af_callback_keys + newsk->sk_family,
                                af_family_clock_key_strings[newsk->sk_family]);

                newsk->sk_dst_cache     = NULL;
                newsk->sk_wmem_queued   = 0;
                newsk->sk_forward_alloc = 0;
                newsk->sk_send_head     = NULL;
                newsk->sk_userlocks     = sk->sk_userlocks & ~SOCK_BINDPORT_LOCK;

                sock_reset_flag(newsk, SOCK_DONE);
                skb_queue_head_init(&newsk->sk_error_queue);

                filter = rcu_dereference_protected(newsk->sk_filter, 1);
                if (filter != NULL)
                        sk_filter_charge(newsk, filter);

                if (unlikely(xfrm_sk_clone_policy(newsk))) {
                        /* It is still raw copy of parent, so invalidate
                         * destructor and make plain sk_free() */
                        newsk->sk_destruct = NULL;
                        bh_unlock_sock(newsk);
                        sk_free(newsk);
                        newsk = NULL;
                        goto out;
                }

                newsk->sk_err      = 0;
                newsk->sk_priority = 0;
                /*
                 * Before updating sk_refcnt, we must commit prior changes to memory
                 * (Documentation/RCU/rculist_nulls.txt for details)
                 */
                smp_wmb();
                atomic_set(&newsk->sk_refcnt, 2);

                /*
                 * Increment the counter in the same struct proto as the master
                 * sock (sk_refcnt_debug_inc uses newsk->sk_prot->socks, that
                 * is the same as sk->sk_prot->socks, as this field was copied
                 * with memcpy).
                 *
                 * This _changes_ the previous behaviour, where
                 * tcp_create_openreq_child always was incrementing the
                 * equivalent to tcp_prot->socks (inet_sock_nr), so this have
                 * to be taken into account in all callers. -acme
                 */
                sk_refcnt_debug_inc(newsk);
                sk_set_socket(newsk, NULL);
                newsk->sk_wq = NULL;

                sk_update_clone(sk, newsk);

                if (newsk->sk_prot->sockets_allocated)
                        sk_sockets_allocated_inc(newsk);

                if (newsk->sk_flags & SK_FLAGS_TIMESTAMP)
                        net_enable_timestamp();
        }
out:
        return newsk;
}
EXPORT_SYMBOL_GPL(sk_clone_lock);

void sk_setup_caps(struct sock *sk, struct dst_entry *dst)
{
        __sk_dst_set(sk, dst);
        sk->sk_route_caps = dst->dev->features;
        if (sk->sk_route_caps & NETIF_F_GSO)
                sk->sk_route_caps |= NETIF_F_GSO_SOFTWARE;
        sk->sk_route_caps &= ~sk->sk_route_nocaps;
        if (sk_can_gso(sk)) {
                if (dst->header_len) {
                        sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
                } else {
                        sk->sk_route_caps |= NETIF_F_SG | NETIF_F_HW_CSUM;
                        sk->sk_gso_max_size = dst->dev->gso_max_size;
                        sk->sk_gso_max_segs = dst->dev->gso_max_segs;
                }
        }
}
EXPORT_SYMBOL_GPL(sk_setup_caps);

/*
 *      Simple resource managers for sockets.
 */


/*
 * Write buffer destructor automatically called from kfree_skb.
 */
void sock_wfree(struct sk_buff *skb)
{
        struct sock *sk = skb->sk;
        unsigned int len = skb->truesize;

        if (!sock_flag(sk, SOCK_USE_WRITE_QUEUE)) {
                /*
                 * Keep a reference on sk_wmem_alloc, this will be released
                 * after sk_write_space() call
                 */
                atomic_sub(len - 1, &sk->sk_wmem_alloc);
                sk->sk_write_space(sk);
                len = 1;
        }
        /*
         * if sk_wmem_alloc reaches 0, we must finish what sk_free()
         * could not do because of in-flight packets
         */
        if (atomic_sub_and_test(len, &sk->sk_wmem_alloc))
                __sk_free(sk);
}
EXPORT_SYMBOL(sock_wfree);

void skb_orphan_partial(struct sk_buff *skb)
{
        /* TCP stack sets skb->ooo_okay based on sk_wmem_alloc,
         * so we do not completely orphan skb, but transfert all
         * accounted bytes but one, to avoid unexpected reorders.
         */
        if (skb->destructor == sock_wfree
#ifdef CONFIG_INET
            || skb->destructor == tcp_wfree
#endif
                ) {
                atomic_sub(skb->truesize - 1, &skb->sk->sk_wmem_alloc);
                skb->truesize = 1;
        } else {
                skb_orphan(skb);
        }
}
EXPORT_SYMBOL(skb_orphan_partial);

/*
 * Read buffer destructor automatically called from kfree_skb.
 */
void sock_rfree(struct sk_buff *skb)
{
        struct sock *sk = skb->sk;
        unsigned int len = skb->truesize;

        atomic_sub(len, &sk->sk_rmem_alloc);
        sk_mem_uncharge(sk, len);
}
EXPORT_SYMBOL(sock_rfree);

void sock_edemux(struct sk_buff *skb)
{
        struct sock *sk = skb->sk;

#ifdef CONFIG_INET
        if (sk->sk_state == TCP_TIME_WAIT)
                inet_twsk_put(inet_twsk(sk));
        else
#endif
                sock_put(sk);
}
EXPORT_SYMBOL(sock_edemux);

kuid_t sock_i_uid(struct sock *sk)
{
        kuid_t uid;

        read_lock_bh(&sk->sk_callback_lock);
        uid = sk->sk_socket ? SOCK_INODE(sk->sk_socket)->i_uid : GLOBAL_ROOT_UID;
        read_unlock_bh(&sk->sk_callback_lock);
        return uid;
}
EXPORT_SYMBOL(sock_i_uid);

unsigned long sock_i_ino(struct sock *sk)
{
        unsigned long ino;

        read_lock_bh(&sk->sk_callback_lock);
        ino = sk->sk_socket ? SOCK_INODE(sk->sk_socket)->i_ino : 0;
        read_unlock_bh(&sk->sk_callback_lock);
        return ino;
}
EXPORT_SYMBOL(sock_i_ino);

/*
 * Allocate a skb from the socket's send buffer.
 */
struct sk_buff *sock_wmalloc(struct sock *sk, unsigned long size, int force,
                             gfp_t priority)
{
        if (force || atomic_read(&sk->sk_wmem_alloc) < sk->sk_sndbuf) {
                struct sk_buff *skb = alloc_skb(size, priority);
                if (skb) {
                        skb_set_owner_w(skb, sk);
                        return skb;
                }
        }
        return NULL;
}
EXPORT_SYMBOL(sock_wmalloc);

/*
 * Allocate a skb from the socket's receive buffer.
 */
struct sk_buff *sock_rmalloc(struct sock *sk, unsigned long size, int force,
                             gfp_t priority)
{
        if (force || atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf) {
                struct sk_buff *skb = alloc_skb(size, priority);
                if (skb) {
                        skb_set_owner_r(skb, sk);
                        return skb;
                }
        }
        return NULL;
}

/*
 * Allocate a memory block from the socket's option memory buffer.
 */
void *sock_kmalloc(struct sock *sk, int size, gfp_t priority)
{
        if ((unsigned int)size <= sysctl_optmem_max &&
            atomic_read(&sk->sk_omem_alloc) + size < sysctl_optmem_max) {
                void *mem;
                /* First do the add, to avoid the race if kmalloc
                 * might sleep.
                 */
                atomic_add(size, &sk->sk_omem_alloc);
                mem = kmalloc(size, priority);
                if (mem)
                        return mem;
                atomic_sub(size, &sk->sk_omem_alloc);
        }
        return NULL;
}
EXPORT_SYMBOL(sock_kmalloc);

/*
 * Free an option memory block.
 */
void sock_kfree_s(struct sock *sk, void *mem, int size)
{
        kfree(mem);
        atomic_sub(size, &sk->sk_omem_alloc);
}
EXPORT_SYMBOL(sock_kfree_s);

/* It is almost wait_for_tcp_memory minus release_sock/lock_sock.
   I think, these locks should be removed for datagram sockets.
 */
static long sock_wait_for_wmem(struct sock *sk, long timeo)
{
        DEFINE_WAIT(wait);

        clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
        for (;;) {
                if (!timeo)
                        break;
                if (signal_pending(current))
                        break;
                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
                prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
                if (atomic_read(&sk->sk_wmem_alloc) < sk->sk_sndbuf)
                        break;
                if (sk->sk_shutdown & SEND_SHUTDOWN)
                        break;
                if (sk->sk_err)
                        break;
                timeo = schedule_timeout(timeo);
        }
        finish_wait(sk_sleep(sk), &wait);
        return timeo;
}


/*
 *      Generic send/receive buffer handlers
 */

struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len,
                                     unsigned long data_len, int noblock,
                                     int *errcode, int max_page_order)
{
        struct sk_buff *skb = NULL;
        unsigned long chunk;
        gfp_t gfp_mask;
        long timeo;
        int err;
        int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
        struct page *page;
        int i;

        err = -EMSGSIZE;
        if (npages > MAX_SKB_FRAGS)
                goto failure;

        timeo = sock_sndtimeo(sk, noblock);
        while (!skb) {
                err = sock_error(sk);
                if (err != 0)
                        goto failure;

                err = -EPIPE;
                if (sk->sk_shutdown & SEND_SHUTDOWN)
                        goto failure;

                if (atomic_read(&sk->sk_wmem_alloc) >= sk->sk_sndbuf) {
                        set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
                        set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
                        err = -EAGAIN;
                        if (!timeo)
                                goto failure;
                        if (signal_pending(current))
                                goto interrupted;
                        timeo = sock_wait_for_wmem(sk, timeo);
                        continue;
                }

                err = -ENOBUFS;
                gfp_mask = sk->sk_allocation;
                if (gfp_mask & __GFP_WAIT)
                        gfp_mask |= __GFP_REPEAT;

                skb = alloc_skb(header_len, gfp_mask);
                if (!skb)
                        goto failure;

                skb->truesize += data_len;

                for (i = 0; npages > 0; i++) {
                        int order = max_page_order;

                        while (order) {
                                if (npages >= 1 << order) {
                                        page = alloc_pages(sk->sk_allocation |
                                                           __GFP_COMP | __GFP_NOWARN,
                                                           order);
                                        if (page)
                                                goto fill_page;
                                }
                                order--;
                        }
                        page = alloc_page(sk->sk_allocation);
                        if (!page)
                                goto failure;
fill_page:
                        chunk = min_t(unsigned long, data_len,
                                      PAGE_SIZE << order);
                        skb_fill_page_desc(skb, i, page, 0, chunk);
                        data_len -= chunk;
                        npages -= 1 << order;
                }
        }

        skb_set_owner_w(skb, sk);
        return skb;

interrupted:
        err = sock_intr_errno(timeo);
failure:
        kfree_skb(skb);
        *errcode = err;
        return NULL;
}
EXPORT_SYMBOL(sock_alloc_send_pskb);

struct sk_buff *sock_alloc_send_skb(struct sock *sk, unsigned long size,
                                    int noblock, int *errcode)
{
        return sock_alloc_send_pskb(sk, size, 0, noblock, errcode, 0);
}
EXPORT_SYMBOL(sock_alloc_send_skb);

/* On 32bit arches, an skb frag is limited to 2^15 */
#define SKB_FRAG_PAGE_ORDER     get_order(32768)

bool sk_page_frag_refill(struct sock *sk, struct page_frag *pfrag)
{
        int order;

        if (pfrag->page) {
                if (atomic_read(&pfrag->page->_count) == 1) {
                        pfrag->offset = 0;
                        return true;
                }
                if (pfrag->offset < pfrag->size)
                        return true;
                put_page(pfrag->page);
        }

        /* We restrict high order allocations to users that can afford to wait */
        order = (sk->sk_allocation & __GFP_WAIT) ? SKB_FRAG_PAGE_ORDER : 0;

        do {
                gfp_t gfp = sk->sk_allocation;

                if (order)
                        gfp |= __GFP_COMP | __GFP_NOWARN;
                pfrag->page = alloc_pages(gfp, order);
                if (likely(pfrag->page)) {
                        pfrag->offset = 0;
                        pfrag->size = PAGE_SIZE << order;
                        return true;
                }
        } while (--order >= 0);

        sk_enter_memory_pressure(sk);
        sk_stream_moderate_sndbuf(sk);
        return false;
}
EXPORT_SYMBOL(sk_page_frag_refill);

static void __lock_sock(struct sock *sk)
        __releases(&sk->sk_lock.slock)
        __acquires(&sk->sk_lock.slock)
{
        DEFINE_WAIT(wait);

        for (;;) {
                prepare_to_wait_exclusive(&sk->sk_lock.wq, &wait,
                                        TASK_UNINTERRUPTIBLE);
                spin_unlock_bh(&sk->sk_lock.slock);
                schedule();
                spin_lock_bh(&sk->sk_lock.slock);
                if (!sock_owned_by_user(sk))
                        break;
        }
        finish_wait(&sk->sk_lock.wq, &wait);
}

static void __release_sock(struct sock *sk)
        __releases(&sk->sk_lock.slock)
        __acquires(&sk->sk_lock.slock)
{
        struct sk_buff *skb = sk->sk_backlog.head;

        do {
                sk->sk_backlog.head = sk->sk_backlog.tail = NULL;
                bh_unlock_sock(sk);

                do {
                        struct sk_buff *next = skb->next;

                        prefetch(next);
                        WARN_ON_ONCE(skb_dst_is_noref(skb));
                        skb->next = NULL;
                        sk_backlog_rcv(sk, skb);

                        /*
                         * We are in process context here with softirqs
                         * disabled, use cond_resched_softirq() to preempt.
                         * This is safe to do because we've taken the backlog
                         * queue private:
                         */
                        cond_resched_softirq();

                        skb = next;
                } while (skb != NULL);

                bh_lock_sock(sk);
        } while ((skb = sk->sk_backlog.head) != NULL);

        /*
         * Doing the zeroing here guarantee we can not loop forever
         * while a wild producer attempts to flood us.
         */
        sk->sk_backlog.len = 0;
}

/**
 * sk_wait_data - wait for data to arrive at sk_receive_queue
 * @sk:    sock to wait on
 * @timeo: for how long
 *
 * Now socket state including sk->sk_err is changed only under lock,
 * hence we may omit checks after joining wait queue.
 * We check receive queue before schedule() only as optimization;
 * it is very likely that release_sock() added new data.
 */
int sk_wait_data(struct sock *sk, long *timeo)
{
        int rc;
        DEFINE_WAIT(wait);

        prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
        set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
        rc = sk_wait_event(sk, timeo, !skb_queue_empty(&sk->sk_receive_queue));
        clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
        finish_wait(sk_sleep(sk), &wait);
        return rc;
}
EXPORT_SYMBOL(sk_wait_data);

/**
 *      __sk_mem_schedule - increase sk_forward_alloc and memory_allocated
 *      @sk: socket
 *      @size: memory size to allocate
 *      @kind: allocation type
 *
 *      If kind is SK_MEM_SEND, it means wmem allocation. Otherwise it means
 *      rmem allocation. This function assumes that protocols which have
 *      memory_pressure use sk_wmem_queued as write buffer accounting.
 */
int __sk_mem_schedule(struct sock *sk, int size, int kind)
{
        struct proto *prot = sk->sk_prot;
        int amt = sk_mem_pages(size);
        long allocated;
        int parent_status = UNDER_LIMIT;

        sk->sk_forward_alloc += amt * SK_MEM_QUANTUM;

        allocated = sk_memory_allocated_add(sk, amt, &parent_status);

        /* Under limit. */
        if (parent_status == UNDER_LIMIT &&
                        allocated <= sk_prot_mem_limits(sk, 0)) {
                sk_leave_memory_pressure(sk);
                return 1;
        }

        /* Under pressure. (we or our parents) */
        if ((parent_status > SOFT_LIMIT) ||
                        allocated > sk_prot_mem_limits(sk, 1))
                sk_enter_memory_pressure(sk);

        /* Over hard limit (we or our parents) */
        if ((parent_status == OVER_LIMIT) ||
                        (allocated > sk_prot_mem_limits(sk, 2)))
                goto suppress_allocation;

        /* guarantee minimum buffer size under pressure */
        if (kind == SK_MEM_RECV) {
                if (atomic_read(&sk->sk_rmem_alloc) < prot->sysctl_rmem[0])
                        return 1;

        } else { /* SK_MEM_SEND */
                if (sk->sk_type == SOCK_STREAM) {

                        if (sk->sk_wmem_queued < prot->sysctl_wmem[0])
                                return 1;
                } else if (atomic_read(&sk->sk_wmem_alloc) <
                           prot->sysctl_wmem[0])
                                return 1;
        }

        if (sk_has_memory_pressure(sk)) {
                int alloc;

                if (!sk_under_memory_pressure(sk))
                        return 1;
                alloc = sk_sockets_allocated_read_positive(sk);
                if (sk_prot_mem_limits(sk, 2) > alloc *
                    sk_mem_pages(sk->sk_wmem_queued +
                                 atomic_read(&sk->sk_rmem_alloc) +
                                 sk->sk_forward_alloc))
                        return 1;
        }

suppress_allocation:

        if (kind == SK_MEM_SEND && sk->sk_type == SOCK_STREAM) {
                sk_stream_moderate_sndbuf(sk);

                /* Fail only if socket is _under_ its sndbuf.
                 * In this case we cannot block, so that we have to fail.
                 */
                if (sk->sk_wmem_queued + size >= sk->sk_sndbuf)
                        return 1;
        }

        trace_sock_exceed_buf_limit(sk, prot, allocated);

        /* Alas. Undo changes. */
        sk->sk_forward_alloc -= amt * SK_MEM_QUANTUM;

        sk_memory_allocated_sub(sk, amt);

        return 0;
}
EXPORT_SYMBOL(__sk_mem_schedule);

/**
 *      __sk_reclaim - reclaim memory_allocated
 *      @sk: socket
 */
void __sk_mem_reclaim(struct sock *sk)
{
        sk_memory_allocated_sub(sk,
                                sk->sk_forward_alloc >> SK_MEM_QUANTUM_SHIFT);
        sk->sk_forward_alloc &= SK_MEM_QUANTUM - 1;

        if (sk_under_memory_pressure(sk) &&
            (sk_memory_allocated(sk) < sk_prot_mem_limits(sk, 0)))
                sk_leave_memory_pressure(sk);
}
EXPORT_SYMBOL(__sk_mem_reclaim);


/*
 * Set of default routines for initialising struct proto_ops when
 * the protocol does not support a particular function. In certain
 * cases where it makes no sense for a protocol to have a "do nothing"
 * function, some default processing is provided.
 */

int sock_no_bind(struct socket *sock, struct sockaddr *saddr, int len)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL(sock_no_bind);

int sock_no_connect(struct socket *sock, struct sockaddr *saddr,
                    int len, int flags)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL(sock_no_connect);

int sock_no_socketpair(struct socket *sock1, struct socket *sock2)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL(sock_no_socketpair);

int sock_no_accept(struct socket *sock, struct socket *newsock, int flags)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL(sock_no_accept);

int sock_no_getname(struct socket *sock, struct sockaddr *saddr,
                    int *len, int peer)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL(sock_no_getname);

unsigned int sock_no_poll(struct file *file, struct socket *sock, poll_table *pt)
{
        return 0;
}
EXPORT_SYMBOL(sock_no_poll);

int sock_no_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL(sock_no_ioctl);

int sock_no_listen(struct socket *sock, int backlog)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL(sock_no_listen);

int sock_no_shutdown(struct socket *sock, int how)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL(sock_no_shutdown);

int sock_no_setsockopt(struct socket *sock, int level, int optname,
                    char __user *optval, unsigned int optlen)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL(sock_no_setsockopt);

int sock_no_getsockopt(struct socket *sock, int level, int optname,
                    char __user *optval, int __user *optlen)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL(sock_no_getsockopt);

int sock_no_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *m,
                    size_t len)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL(sock_no_sendmsg);

int sock_no_recvmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *m,
                    size_t len, int flags)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL(sock_no_recvmsg);

int sock_no_mmap(struct file *file, struct socket *sock, struct vm_area_struct *vma)
{
        /* Mirror missing mmap method error code */
        return -ENODEV;
}
EXPORT_SYMBOL(sock_no_mmap);

ssize_t sock_no_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags)
{
        ssize_t res;
        struct msghdr msg = {.msg_flags = flags};
        struct kvec iov;
        char *kaddr = kmap(page);
        iov.iov_base = kaddr + offset;
        iov.iov_len = size;
        res = kernel_sendmsg(sock, &msg, &iov, 1, size);
        kunmap(page);
        return res;
}
EXPORT_SYMBOL(sock_no_sendpage);

/*
 *      Default Socket Callbacks
 */

static void sock_def_wakeup(struct sock *sk)
{
        struct socket_wq *wq;

        rcu_read_lock();
        wq = rcu_dereference(sk->sk_wq);
        if (wq_has_sleeper(wq))
                wake_up_interruptible_all(&wq->wait);
        rcu_read_unlock();
}

static void sock_def_error_report(struct sock *sk)
{
        struct socket_wq *wq;

        rcu_read_lock();
        wq = rcu_dereference(sk->sk_wq);
        if (wq_has_sleeper(wq))
                wake_up_interruptible_poll(&wq->wait, POLLERR);
        sk_wake_async(sk, SOCK_WAKE_IO, POLL_ERR);
        rcu_read_unlock();
}

static void sock_def_readable(struct sock *sk, int len)
{
        struct socket_wq *wq;

        rcu_read_lock();
        wq = rcu_dereference(sk->sk_wq);
        if (wq_has_sleeper(wq))
                wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLPRI |
                                                POLLRDNORM | POLLRDBAND);
        sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
        rcu_read_unlock();
}

static void sock_def_write_space(struct sock *sk)
{
        struct socket_wq *wq;

        rcu_read_lock();

        /* Do not wake up a writer until he can make "significant"
         * progress.  --DaveM
         */
        if ((atomic_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf) {
                wq = rcu_dereference(sk->sk_wq);
                if (wq_has_sleeper(wq))
                        wake_up_interruptible_sync_poll(&wq->wait, POLLOUT |
                                                POLLWRNORM | POLLWRBAND);

                /* Should agree with poll, otherwise some programs break */
                if (sock_writeable(sk))
                        sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
        }

        rcu_read_unlock();
}

static void sock_def_destruct(struct sock *sk)
{
        kfree(sk->sk_protinfo);
}

void sk_send_sigurg(struct sock *sk)
{
        if (sk->sk_socket && sk->sk_socket->file)
                if (send_sigurg(&sk->sk_socket->file->f_owner))
                        sk_wake_async(sk, SOCK_WAKE_URG, POLL_PRI);
}
EXPORT_SYMBOL(sk_send_sigurg);

void sk_reset_timer(struct sock *sk, struct timer_list* timer,
                    unsigned long expires)
{
        if (!mod_timer(timer, expires))
                sock_hold(sk);
}
EXPORT_SYMBOL(sk_reset_timer);

void sk_stop_timer(struct sock *sk, struct timer_list* timer)
{
        if (del_timer(timer))
                __sock_put(sk);
}
EXPORT_SYMBOL(sk_stop_timer);

void sock_init_data(struct socket *sock, struct sock *sk)
{
        skb_queue_head_init(&sk->sk_receive_queue);
        skb_queue_head_init(&sk->sk_write_queue);
        skb_queue_head_init(&sk->sk_error_queue);
#ifdef CONFIG_NET_DMA
        skb_queue_head_init(&sk->sk_async_wait_queue);
#endif

        sk->sk_send_head        =       NULL;

        init_timer(&sk->sk_timer);

        sk->sk_allocation       =       GFP_KERNEL;
        sk->sk_rcvbuf           =       sysctl_rmem_default;
        sk->sk_sndbuf           =       sysctl_wmem_default;
        sk->sk_state            =       TCP_CLOSE;
        sk_set_socket(sk, sock);

        sock_set_flag(sk, SOCK_ZAPPED);

        if (sock) {
                sk->sk_type     =       sock->type;
                sk->sk_wq       =       sock->wq;
                sock->sk        =       sk;
        } else
                sk->sk_wq       =       NULL;

        spin_lock_init(&sk->sk_dst_lock);
        rwlock_init(&sk->sk_callback_lock);
        lockdep_set_class_and_name(&sk->sk_callback_lock,
                        af_callback_keys + sk->sk_family,
                        af_family_clock_key_strings[sk->sk_family]);

        sk->sk_state_change     =       sock_def_wakeup;
        sk->sk_data_ready       =       sock_def_readable;
        sk->sk_write_space      =       sock_def_write_space;
        sk->sk_error_report     =       sock_def_error_report;
        sk->sk_destruct         =       sock_def_destruct;

        sk->sk_frag.page        =       NULL;
        sk->sk_frag.offset      =       0;
        sk->sk_peek_off         =       -1;

        sk->sk_peer_pid         =       NULL;
        sk->sk_peer_cred        =       NULL;
        sk->sk_write_pending    =       0;
        sk->sk_rcvlowat         =       1;
        sk->sk_rcvtimeo         =       MAX_SCHEDULE_TIMEOUT;
        sk->sk_sndtimeo         =       MAX_SCHEDULE_TIMEOUT;

        sk->sk_stamp = ktime_set(-1L, 0);

#ifdef CONFIG_NET_RX_BUSY_POLL
        sk->sk_napi_id          =       0;
        sk->sk_ll_usec          =       sysctl_net_busy_read;
#endif

        sk->sk_pacing_rate = ~0U;
        /*
         * Before updating sk_refcnt, we must commit prior changes to memory
         * (Documentation/RCU/rculist_nulls.txt for details)
         */
        smp_wmb();
        atomic_set(&sk->sk_refcnt, 1);
        atomic_set(&sk->sk_drops, 0);
}
EXPORT_SYMBOL(sock_init_data);

void lock_sock_nested(struct sock *sk, int subclass)
{
        might_sleep();
        spin_lock_bh(&sk->sk_lock.slock);
        if (sk->sk_lock.owned)
                __lock_sock(sk);
        sk->sk_lock.owned = 1;
        spin_unlock(&sk->sk_lock.slock);
        /*
         * The sk_lock has mutex_lock() semantics here:
         */
        mutex_acquire(&sk->sk_lock.dep_map, subclass, 0, _RET_IP_);
        local_bh_enable();
}
EXPORT_SYMBOL(lock_sock_nested);

void release_sock(struct sock *sk)
{
        /*
         * The sk_lock has mutex_unlock() semantics:
         */
        mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_);

        spin_lock_bh(&sk->sk_lock.slock);
        if (sk->sk_backlog.tail)
                __release_sock(sk);

        if (sk->sk_prot->release_cb)
                sk->sk_prot->release_cb(sk);

        sk->sk_lock.owned = 0;
        if (waitqueue_active(&sk->sk_lock.wq))
                wake_up(&sk->sk_lock.wq);
        spin_unlock_bh(&sk->sk_lock.slock);
}
EXPORT_SYMBOL(release_sock);

/**
 * lock_sock_fast - fast version of lock_sock
 * @sk: socket
 *
 * This version should be used for very small section, where process wont block
 * return false if fast path is taken
 *   sk_lock.slock locked, owned = 0, BH disabled
 * return true if slow path is taken
 *   sk_lock.slock unlocked, owned = 1, BH enabled
 */
bool lock_sock_fast(struct sock *sk)
{
        might_sleep();
        spin_lock_bh(&sk->sk_lock.slock);

        if (!sk->sk_lock.owned)
                /*
                 * Note : We must disable BH
                 */
                return false;

        __lock_sock(sk);
        sk->sk_lock.owned = 1;
        spin_unlock(&sk->sk_lock.slock);
        /*
         * The sk_lock has mutex_lock() semantics here:
         */
        mutex_acquire(&sk->sk_lock.dep_map, 0, 0, _RET_IP_);
        local_bh_enable();
        return true;
}
EXPORT_SYMBOL(lock_sock_fast);

int sock_get_timestamp(struct sock *sk, struct timeval __user *userstamp)
{
        struct timeval tv;
        if (!sock_flag(sk, SOCK_TIMESTAMP))
                sock_enable_timestamp(sk, SOCK_TIMESTAMP);
        tv = ktime_to_timeval(sk->sk_stamp);
        if (tv.tv_sec == -1)
                return -ENOENT;
        if (tv.tv_sec == 0) {
                sk->sk_stamp = ktime_get_real();
                tv = ktime_to_timeval(sk->sk_stamp);
        }
        return copy_to_user(userstamp, &tv, sizeof(tv)) ? -EFAULT : 0;
}
EXPORT_SYMBOL(sock_get_timestamp);

int sock_get_timestampns(struct sock *sk, struct timespec __user *userstamp)
{
        struct timespec ts;
        if (!sock_flag(sk, SOCK_TIMESTAMP))
                sock_enable_timestamp(sk, SOCK_TIMESTAMP);
        ts = ktime_to_timespec(sk->sk_stamp);
        if (ts.tv_sec == -1)
                return -ENOENT;
        if (ts.tv_sec == 0) {
                sk->sk_stamp = ktime_get_real();
                ts = ktime_to_timespec(sk->sk_stamp);
        }
        return copy_to_user(userstamp, &ts, sizeof(ts)) ? -EFAULT : 0;
}
EXPORT_SYMBOL(sock_get_timestampns);

void sock_enable_timestamp(struct sock *sk, int flag)
{
        if (!sock_flag(sk, flag)) {
                unsigned long previous_flags = sk->sk_flags;

                sock_set_flag(sk, flag);
                /*
                 * we just set one of the two flags which require net
                 * time stamping, but time stamping might have been on
                 * already because of the other one
                 */
                if (!(previous_flags & SK_FLAGS_TIMESTAMP))
                        net_enable_timestamp();
        }
}

int sock_recv_errqueue(struct sock *sk, struct msghdr *msg, int len,
                       int level, int type)
{
        struct sock_exterr_skb *serr;
        struct sk_buff *skb, *skb2;
        int copied, err;

        err = -EAGAIN;
        skb = skb_dequeue(&sk->sk_error_queue);
        if (skb == NULL)
                goto out;

        copied = skb->len;
        if (copied > len) {
                msg->msg_flags |= MSG_TRUNC;
                copied = len;
        }
        err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
        if (err)
                goto out_free_skb;

        sock_recv_timestamp(msg, sk, skb);

        serr = SKB_EXT_ERR(skb);
        put_cmsg(msg, level, type, sizeof(serr->ee), &serr->ee);

        msg->msg_flags |= MSG_ERRQUEUE;
        err = copied;

        /* Reset and regenerate socket error */
        spin_lock_bh(&sk->sk_error_queue.lock);
        sk->sk_err = 0;
        if ((skb2 = skb_peek(&sk->sk_error_queue)) != NULL) {
                sk->sk_err = SKB_EXT_ERR(skb2)->ee.ee_errno;
                spin_unlock_bh(&sk->sk_error_queue.lock);
                sk->sk_error_report(sk);
        } else
                spin_unlock_bh(&sk->sk_error_queue.lock);

out_free_skb:
        kfree_skb(skb);
out:
        return err;
}
EXPORT_SYMBOL(sock_recv_errqueue);

/*
 *      Get a socket option on an socket.
 *
 *      FIX: POSIX 1003.1g is very ambiguous here. It states that
 *      asynchronous errors should be reported by getsockopt. We assume
 *      this means if you specify SO_ERROR (otherwise whats the point of it).
 */
int sock_common_getsockopt(struct socket *sock, int level, int optname,
                           char __user *optval, int __user *optlen)
{
        struct sock *sk = sock->sk;

        return sk->sk_prot->getsockopt(sk, level, optname, optval, optlen);
}
EXPORT_SYMBOL(sock_common_getsockopt);

#ifdef CONFIG_COMPAT
int compat_sock_common_getsockopt(struct socket *sock, int level, int optname,
                                  char __user *optval, int __user *optlen)
{
        struct sock *sk = sock->sk;

        if (sk->sk_prot->compat_getsockopt != NULL)
                return sk->sk_prot->compat_getsockopt(sk, level, optname,
                                                      optval, optlen);
        return sk->sk_prot->getsockopt(sk, level, optname, optval, optlen);
}
EXPORT_SYMBOL(compat_sock_common_getsockopt);
#endif

int sock_common_recvmsg(struct kiocb *iocb, struct socket *sock,
                        struct msghdr *msg, size_t size, int flags)
{
        struct sock *sk = sock->sk;
        int addr_len = 0;
        int err;

        err = sk->sk_prot->recvmsg(iocb, sk, msg, size, flags & MSG_DONTWAIT,
                                   flags & ~MSG_DONTWAIT, &addr_len);
        if (err >= 0)
                msg->msg_namelen = addr_len;
        return err;
}
EXPORT_SYMBOL(sock_common_recvmsg);

/*
 *      Set socket options on an inet socket.
 */
int sock_common_setsockopt(struct socket *sock, int level, int optname,
                           char __user *optval, unsigned int optlen)
{
        struct sock *sk = sock->sk;

        return sk->sk_prot->setsockopt(sk, level, optname, optval, optlen);
}
EXPORT_SYMBOL(sock_common_setsockopt);

#ifdef CONFIG_COMPAT
int compat_sock_common_setsockopt(struct socket *sock, int level, int optname,
                                  char __user *optval, unsigned int optlen)
{
        struct sock *sk = sock->sk;

        if (sk->sk_prot->compat_setsockopt != NULL)
                return sk->sk_prot->compat_setsockopt(sk, level, optname,
                                                      optval, optlen);
        return sk->sk_prot->setsockopt(sk, level, optname, optval, optlen);
}
EXPORT_SYMBOL(compat_sock_common_setsockopt);
#endif

void sk_common_release(struct sock *sk)
{
        if (sk->sk_prot->destroy)
                sk->sk_prot->destroy(sk);

        /*
         * Observation: when sock_common_release is called, processes have
         * no access to socket. But net still has.
         * Step one, detach it from networking:
         *
         * A. Remove from hash tables.
         */

        sk->sk_prot->unhash(sk);

        /*
         * In this point socket cannot receive new packets, but it is possible
         * that some packets are in flight because some CPU runs receiver and
         * did hash table lookup before we unhashed socket. They will achieve
         * receive queue and will be purged by socket destructor.
         *
         * Also we still have packets pending on receive queue and probably,
         * our own packets waiting in device queues. sock_destroy will drain
         * receive queue, but transmitted packets will delay socket destruction
         * until the last reference will be released.
         */

        sock_orphan(sk);

        xfrm_sk_free_policy(sk);

        sk_refcnt_debug_release(sk);

        if (sk->sk_frag.page) {
                put_page(sk->sk_frag.page);
                sk->sk_frag.page = NULL;
        }

        sock_put(sk);
}
EXPORT_SYMBOL(sk_common_release);

#ifdef CONFIG_PROC_FS
#define PROTO_INUSE_NR  64      /* should be enough for the first time */
struct prot_inuse {
        int val[PROTO_INUSE_NR];
};

static DECLARE_BITMAP(proto_inuse_idx, PROTO_INUSE_NR);

#ifdef CONFIG_NET_NS
void sock_prot_inuse_add(struct net *net, struct proto *prot, int val)
{
        __this_cpu_add(net->core.inuse->val[prot->inuse_idx], val);
}
EXPORT_SYMBOL_GPL(sock_prot_inuse_add);

int sock_prot_inuse_get(struct net *net, struct proto *prot)
{
        int cpu, idx = prot->inuse_idx;
        int res = 0;

        for_each_possible_cpu(cpu)
                res += per_cpu_ptr(net->core.inuse, cpu)->val[idx];

        return res >= 0 ? res : 0;
}
EXPORT_SYMBOL_GPL(sock_prot_inuse_get);

static int __net_init sock_inuse_init_net(struct net *net)
{
        net->core.inuse = alloc_percpu(struct prot_inuse);
        return net->core.inuse ? 0 : -ENOMEM;
}

static void __net_exit sock_inuse_exit_net(struct net *net)
{
        free_percpu(net->core.inuse);
}

static struct pernet_operations net_inuse_ops = {
        .init = sock_inuse_init_net,
        .exit = sock_inuse_exit_net,
};

static __init int net_inuse_init(void)
{
        if (register_pernet_subsys(&net_inuse_ops))
                panic("Cannot initialize net inuse counters");

        return 0;
}

core_initcall(net_inuse_init);
#else
static DEFINE_PER_CPU(struct prot_inuse, prot_inuse);

void sock_prot_inuse_add(struct net *net, struct proto *prot, int val)
{
        __this_cpu_add(prot_inuse.val[prot->inuse_idx], val);
}
EXPORT_SYMBOL_GPL(sock_prot_inuse_add);

int sock_prot_inuse_get(struct net *net, struct proto *prot)
{
        int cpu, idx = prot->inuse_idx;
        int res = 0;

        for_each_possible_cpu(cpu)
                res += per_cpu(prot_inuse, cpu).val[idx];

        return res >= 0 ? res : 0;
}
EXPORT_SYMBOL_GPL(sock_prot_inuse_get);
#endif

static void assign_proto_idx(struct proto *prot)
{
        prot->inuse_idx = find_first_zero_bit(proto_inuse_idx, PROTO_INUSE_NR);

        if (unlikely(prot->inuse_idx == PROTO_INUSE_NR - 1)) {
                pr_err("PROTO_INUSE_NR exhausted\n");
                return;
        }

        set_bit(prot->inuse_idx, proto_inuse_idx);
}

static void release_proto_idx(struct proto *prot)
{
        if (prot->inuse_idx != PROTO_INUSE_NR - 1)
                clear_bit(prot->inuse_idx, proto_inuse_idx);
}
#else
static inline void assign_proto_idx(struct proto *prot)
{
}

static inline void release_proto_idx(struct proto *prot)
{
}
#endif

int proto_register(struct proto *prot, int alloc_slab)
{
        if (alloc_slab) {
                prot->slab = kmem_cache_create(prot->name, prot->obj_size, 0,
                                        SLAB_HWCACHE_ALIGN | prot->slab_flags,
                                        NULL);

                if (prot->slab == NULL) {
                        pr_crit("%s: Can't create sock SLAB cache!\n",
                                prot->name);
                        goto out;
                }

                if (prot->rsk_prot != NULL) {
                        prot->rsk_prot->slab_name = kasprintf(GFP_KERNEL, "request_sock_%s", prot->name);
                        if (prot->rsk_prot->slab_name == NULL)
                                goto out_free_sock_slab;

                        prot->rsk_prot->slab = kmem_cache_create(prot->rsk_prot->slab_name,
                                                                 prot->rsk_prot->obj_size, 0,
                                                                 SLAB_HWCACHE_ALIGN, NULL);

                        if (prot->rsk_prot->slab == NULL) {
                                pr_crit("%s: Can't create request sock SLAB cache!\n",
                                        prot->name);
                                goto out_free_request_sock_slab_name;
                        }
                }

                if (prot->twsk_prot != NULL) {
                        prot->twsk_prot->twsk_slab_name = kasprintf(GFP_KERNEL, "tw_sock_%s", prot->name);

                        if (prot->twsk_prot->twsk_slab_name == NULL)
                                goto out_free_request_sock_slab;

                        prot->twsk_prot->twsk_slab =
                                kmem_cache_create(prot->twsk_prot->twsk_slab_name,
                                                  prot->twsk_prot->twsk_obj_size,
                                                  0,
                                                  SLAB_HWCACHE_ALIGN |
                                                        prot->slab_flags,
                                                  NULL);
                        if (prot->twsk_prot->twsk_slab == NULL)
                                goto out_free_timewait_sock_slab_name;
                }
        }

        mutex_lock(&proto_list_mutex);
        list_add(&prot->node, &proto_list);
        assign_proto_idx(prot);
        mutex_unlock(&proto_list_mutex);
        return 0;

out_free_timewait_sock_slab_name:
        kfree(prot->twsk_prot->twsk_slab_name);
out_free_request_sock_slab:
        if (prot->rsk_prot && prot->rsk_prot->slab) {
                kmem_cache_destroy(prot->rsk_prot->slab);
                prot->rsk_prot->slab = NULL;
        }
out_free_request_sock_slab_name:
        if (prot->rsk_prot)
                kfree(prot->rsk_prot->slab_name);
out_free_sock_slab:
        kmem_cache_destroy(prot->slab);
        prot->slab = NULL;
out:
        return -ENOBUFS;
}
EXPORT_SYMBOL(proto_register);

void proto_unregister(struct proto *prot)
{
        mutex_lock(&proto_list_mutex);
        release_proto_idx(prot);
        list_del(&prot->node);
        mutex_unlock(&proto_list_mutex);

        if (prot->slab != NULL) {
                kmem_cache_destroy(prot->slab);
                prot->slab = NULL;
        }

        if (prot->rsk_prot != NULL && prot->rsk_prot->slab != NULL) {
                kmem_cache_destroy(prot->rsk_prot->slab);
                kfree(prot->rsk_prot->slab_name);
                prot->rsk_prot->slab = NULL;
        }

        if (prot->twsk_prot != NULL && prot->twsk_prot->twsk_slab != NULL) {
                kmem_cache_destroy(prot->twsk_prot->twsk_slab);
                kfree(prot->twsk_prot->twsk_slab_name);
                prot->twsk_prot->twsk_slab = NULL;
        }
}
EXPORT_SYMBOL(proto_unregister);

#ifdef CONFIG_PROC_FS
static void *proto_seq_start(struct seq_file *seq, loff_t *pos)
        __acquires(proto_list_mutex)
{
        mutex_lock(&proto_list_mutex);
        return seq_list_start_head(&proto_list, *pos);
}

static void *proto_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        return seq_list_next(v, &proto_list, pos);
}

static void proto_seq_stop(struct seq_file *seq, void *v)
        __releases(proto_list_mutex)
{
        mutex_unlock(&proto_list_mutex);
}

static char proto_method_implemented(const void *method)
{
        return method == NULL ? 'n' : 'y';
}
static long sock_prot_memory_allocated(struct proto *proto)
{
        return proto->memory_allocated != NULL ? proto_memory_allocated(proto) : -1L;
}

static char *sock_prot_memory_pressure(struct proto *proto)
{
        return proto->memory_pressure != NULL ?
        proto_memory_pressure(proto) ? "yes" : "no" : "NI";
}

static void proto_seq_printf(struct seq_file *seq, struct proto *proto)
{

        seq_printf(seq, "%-9s %4u %6d  %6ld   %-3s %6u   %-3s  %-10s "
                        "%2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c\n",
                   proto->name,
                   proto->obj_size,
                   sock_prot_inuse_get(seq_file_net(seq), proto),
                   sock_prot_memory_allocated(proto),
                   sock_prot_memory_pressure(proto),
                   proto->max_header,
                   proto->slab == NULL ? "no" : "yes",
                   module_name(proto->owner),
                   proto_method_implemented(proto->close),
                   proto_method_implemented(proto->connect),
                   proto_method_implemented(proto->disconnect),
                   proto_method_implemented(proto->accept),
                   proto_method_implemented(proto->ioctl),
                   proto_method_implemented(proto->init),
                   proto_method_implemented(proto->destroy),
                   proto_method_implemented(proto->shutdown),
                   proto_method_implemented(proto->setsockopt),
                   proto_method_implemented(proto->getsockopt),
                   proto_method_implemented(proto->sendmsg),
                   proto_method_implemented(proto->recvmsg),
                   proto_method_implemented(proto->sendpage),
                   proto_method_implemented(proto->bind),
                   proto_method_implemented(proto->backlog_rcv),
                   proto_method_implemented(proto->hash),
                   proto_method_implemented(proto->unhash),
                   proto_method_implemented(proto->get_port),
                   proto_method_implemented(proto->enter_memory_pressure));
}

static int proto_seq_show(struct seq_file *seq, void *v)
{
        if (v == &proto_list)
                seq_printf(seq, "%-9s %-4s %-8s %-6s %-5s %-7s %-4s %-10s %s",
                           "protocol",
                           "size",
                           "sockets",
                           "memory",
                           "press",
                           "maxhdr",
                           "slab",
                           "module",
                           "cl co di ac io in de sh ss gs se re sp bi br ha uh gp em\n");
        else
                proto_seq_printf(seq, list_entry(v, struct proto, node));
        return 0;
}

static const struct seq_operations proto_seq_ops = {
        .start  = proto_seq_start,
        .next   = proto_seq_next,
        .stop   = proto_seq_stop,
        .show   = proto_seq_show,
};

static int proto_seq_open(struct inode *inode, struct file *file)
{
        return seq_open_net(inode, file, &proto_seq_ops,
                            sizeof(struct seq_net_private));
}

static const struct file_operations proto_seq_fops = {
        .owner          = THIS_MODULE,
        .open           = proto_seq_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release_net,
};

static __net_init int proto_init_net(struct net *net)
{
        if (!proc_create("protocols", S_IRUGO, net->proc_net, &proto_seq_fops))
                return -ENOMEM;

        return 0;
}

static __net_exit void proto_exit_net(struct net *net)
{
        remove_proc_entry("protocols", net->proc_net);
}


static __net_initdata struct pernet_operations proto_net_ops = {
        .init = proto_init_net,
        .exit = proto_exit_net,
};

static int __init proto_init(void)
{
        return register_pernet_subsys(&proto_net_ops);
}

subsys_initcall(proto_init);

#endif /* PROC_FS */