net/core/sock.c

/*
 * 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 <linux/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/sock_diag.h>

#include <linux/filter.h>
#include <net/sock_reuseport.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);

/**
 * sk_ns_capable - General socket capability test
 * @sk: Socket to use a capability on or through
 * @user_ns: The user namespace of the capability to use
 * @cap: The capability to use
 *
 * Test to see if the opener of the socket had when the socket was
 * created and the current process has the capability @cap in the user
 * namespace @user_ns.
 */
bool sk_ns_capable(const struct sock *sk,
		   struct user_namespace *user_ns, int cap)
{
	return file_ns_capable(sk->sk_socket->file, user_ns, cap) &&
		ns_capable(user_ns, cap);
}
EXPORT_SYMBOL(sk_ns_capable);

/**
 * sk_capable - Socket global capability test
 * @sk: Socket to use a capability on or through
 * @cap: The global capability to use
 *
 * Test to see if the opener of the socket had when the socket was
 * created and the current process has the capability @cap in all user
 * namespaces.
 */
bool sk_capable(const struct sock *sk, int cap)
{
	return sk_ns_capable(sk, &init_user_ns, cap);
}
EXPORT_SYMBOL(sk_capable);

/**
 * sk_net_capable - Network namespace socket capability test
 * @sk: Socket to use a capability on or through
 * @cap: The capability to use
 *
 * Test to see if the opener of the socket had when the socket was created
 * and the current process has the capability @cap over the network namespace
 * the socket is a member of.
 */
bool sk_net_capable(const struct sock *sk, int cap)
{
	return sk_ns_capable(sk, sock_net(sk)->user_ns, cap);
}
EXPORT_SYMBOL(sk_net_capable);

/*
 * 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];

/*
 * 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_KCM"      ,
  "sk_lock-AF_QIPCRTR", "sk_lock-AF_SMC"     , "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_KCM"       ,
  "slock-AF_QIPCRTR", "slock-AF_SMC"     , "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_KCM"      ,
  "clock-AF_QIPCRTR", "clock-AF_SMC"     , "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);

int sysctl_tstamp_allow_data __read_mostly = 1;

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. SOCK_MEMALLOC may be cleared while
	 * it has rmem allocations due to the last swapfile being deactivated
	 * but there is a risk that the socket is unusable due to exceeding
	 * the rmem limits. Reclaim the reserves and obey rmem limits again.
	 */
	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++;
	}
}

static bool sock_needs_netstamp(const struct sock *sk)
{
	switch (sk->sk_family) {
	case AF_UNSPEC:
	case AF_UNIX:
		return false;
	default:
		return true;
	}
}

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


int __sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
{
	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;
	}

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

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

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

	spin_lock_irqsave(&list->lock, flags);
	sock_skb_set_dropcount(sk, skb);
	__skb_queue_tail(list, skb);
	spin_unlock_irqrestore(&list->lock, flags);

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

int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
{
	int err;

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

	return __sock_queue_rcv_skb(sk, skb);
}
EXPORT_SYMBOL(sock_queue_rcv_skb);

int __sk_receive_skb(struct sock *sk, struct sk_buff *skb,
		     const int nested, unsigned int trim_cap, bool refcounted)
{
	int rc = NET_RX_SUCCESS;

	if (sk_filter_trim_cap(sk, skb, trim_cap))
		goto discard_and_relse;

	skb->dev = NULL;

	if (sk_rcvqueues_full(sk, 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:
	if (refcounted)
		sock_put(sk);
	return rc;
discard_and_relse:
	kfree_skb(skb);
	goto out;
}
EXPORT_SYMBOL(__sk_receive_skb);

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);
		sk->sk_dst_pending_confirm = 0;
		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);
}

bool sk_mc_loop(struct sock *sk)
{
	if (dev_recursion_level())
		return false;
	if (!sk)
		return true;
	switch (sk->sk_family) {
	case AF_INET:
		return inet_sk(sk)->mc_loop;
#if IS_ENABLED(CONFIG_IPV6)
	case AF_INET6:
		return inet6_sk(sk)->mc_loop;
#endif
	}
	WARN_ON(1);
	return true;
}
EXPORT_SYMBOL(sk_mc_loop);

/*
 *	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(int, 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(int, val * 2, SOCK_MIN_RCVBUF);
		break;

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

	case SO_KEEPALIVE:
		if (sk->sk_prot->keepalive)
			sk->sk_prot->keepalive(sk, valbool);
		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_tx = 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;
		}

		if (val & SOF_TIMESTAMPING_OPT_ID &&
		    !(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)) {
			if (sk->sk_protocol == IPPROTO_TCP &&
			    sk->sk_type == SOCK_STREAM) {
				if ((1 << sk->sk_state) &
				    (TCPF_CLOSE | TCPF_LISTEN)) {
					ret = -EINVAL;
					break;
				}
				sk->sk_tskey = tcp_sk(sk)->snd_una;
			} else {
				sk->sk_tskey = 0;
			}
		}

		if (val & SOF_TIMESTAMPING_OPT_STATS &&
		    !(val & SOF_TIMESTAMPING_OPT_TSONLY)) {
			ret = -EINVAL;
			break;
		}

		sk->sk_tsflags = val;
		if (val & SOF_TIMESTAMPING_RX_SOFTWARE)
			sock_enable_timestamp(sk,
					      SOCK_TIMESTAMPING_RX_SOFTWARE);
		else
			sock_disable_timestamp(sk,
					       (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE));
		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_ATTACH_BPF:
		ret = -EINVAL;
		if (optlen == sizeof(u32)) {
			u32 ufd;

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

			ret = sk_attach_bpf(ufd, sk);
		}
		break;

	case SO_ATTACH_REUSEPORT_CBPF:
		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_reuseport_attach_filter(&fprog, sk);
		}
		break;

	case SO_ATTACH_REUSEPORT_EBPF:
		ret = -EINVAL;
		if (optlen == sizeof(u32)) {
			u32 ufd;

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

			ret = sk_reuseport_attach_bpf(ufd, 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;

	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)
			ret = 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

	case SO_MAX_PACING_RATE:
		sk->sk_max_pacing_rate = val;
		sk->sk_pacing_rate = min(sk->sk_pacing_rate,
					 sk->sk_max_pacing_rate);
		break;

	case SO_INCOMING_CPU:
		sk->sk_incoming_cpu = val;
		break;

	case SO_CNX_ADVICE:
		if (val == 1)
			dst_negative_advice(sk);
		break;
	default:
		ret = -ENOPROTOOPT;
		break;
	}
	release_sock(sk);
	return ret;
}
EXPORT_SYMBOL(sock_setsockopt);


static 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);
	}
}

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_tx;
		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 = sk->sk_tsflags;
		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_BPF_EXTENSIONS:
		v.val = bpf_tell_extensions();
		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

	case SO_MAX_PACING_RATE:
		v.val = sk->sk_max_pacing_rate;
		break;

	case SO_INCOMING_CPU:
		v.val = sk->sk_incoming_cpu;
		break;

	default:
		/* We implement the SO_SNDLOWAT etc to not be settable
		 * (1003.1g 7).
		 */
		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
}

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)
			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;

	cgroup_sk_free(&sk->sk_cgrp_data);
	mem_cgroup_sk_free(sk);
	security_sk_free(sk);
	if (slab != NULL)
		kmem_cache_free(slab, sk);
	else
		kfree(sk);
	module_put(owner);
}

/**
 *	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
 *	@kern: is this to be a kernel socket?
 */
struct sock *sk_alloc(struct net *net, int family, gfp_t priority,
		      struct proto *prot, int kern)
{
	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);
		sk->sk_net_refcnt = kern ? 0 : 1;
		if (likely(sk->sk_net_refcnt))
			get_net(net);
		sock_net_set(sk, net);
		atomic_set(&sk->sk_wmem_alloc, 1);

		mem_cgroup_sk_alloc(sk);
		cgroup_sk_alloc(&sk->sk_cgrp_data);
		sock_update_classid(&sk->sk_cgrp_data);
		sock_update_netprioidx(&sk->sk_cgrp_data);
	}

	return sk;
}
EXPORT_SYMBOL(sk_alloc);

/* Sockets having SOCK_RCU_FREE will call this function after one RCU
 * grace period. This is the case for UDP sockets and TCP listeners.
 */
static void __sk_destruct(struct rcu_head *head)
{
	struct sock *sk = container_of(head, struct sock, sk_rcu);
	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);
	}
	if (rcu_access_pointer(sk->sk_reuseport_cb))
		reuseport_detach_sock(sk);

	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);
	if (likely(sk->sk_net_refcnt))
		put_net(sock_net(sk));
	sk_prot_free(sk->sk_prot_creator, sk);
}

void sk_destruct(struct sock *sk)
{
	if (sock_flag(sk, SOCK_RCU_FREE))
		call_rcu(&sk->sk_rcu, __sk_destruct);
	else
		__sk_destruct(&sk->sk_rcu);
}

static void __sk_free(struct sock *sk)
{
	if (unlikely(sock_diag_has_destroy_listeners(sk) && sk->sk_net_refcnt))
		sock_diag_broadcast_destroy(sk);
	else
		sk_destruct(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);

/**
 *	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;
	bool is_charged = true;

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

		sock_copy(newsk, sk);

		/* SANITY */
		if (likely(newsk->sk_net_refcnt))
			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);

		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_dst_pending_confirm = 0;
		newsk->sk_wmem_queued	= 0;
		newsk->sk_forward_alloc = 0;
		atomic_set(&newsk->sk_drops, 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)
			/* though it's an empty new sock, the charging may fail
			 * if sysctl_optmem_max was changed between creation of
			 * original socket and cloning
			 */
			is_charged = sk_filter_charge(newsk, filter);

		if (unlikely(!is_charged || xfrm_sk_clone_policy(newsk, sk))) {
			/* 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;
		}
		RCU_INIT_POINTER(newsk->sk_reuseport_cb, NULL);

		newsk->sk_err	   = 0;
		newsk->sk_err_soft = 0;
		newsk->sk_priority = 0;
		newsk->sk_incoming_cpu = raw_smp_processor_id();
		atomic64_set(&newsk->sk_cookie, 0);

		mem_cgroup_sk_alloc(newsk);
		cgroup_sk_alloc(&newsk->sk_cgrp_data);

		/*
		 * 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;

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

		if (sock_needs_netstamp(sk) &&
		    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)
{
	u32 max_segs = 1;

	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;
			max_segs = max_t(u32, dst->dev->gso_max_segs, 1);
		}
	}
	sk->sk_gso_max_segs = 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);

/* This variant of sock_wfree() is used by TCP,
 * since it sets SOCK_USE_WRITE_QUEUE.
 */
void __sock_wfree(struct sk_buff *skb)
{
	struct sock *sk = skb->sk;

	if (atomic_sub_and_test(skb->truesize, &sk->sk_wmem_alloc))
		__sk_free(sk);
}

void skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
{
	skb_orphan(skb);
	skb->sk = sk;
#ifdef CONFIG_INET
	if (unlikely(!sk_fullsock(sk))) {
		skb->destructor = sock_edemux;
		sock_hold(sk);
		return;
	}
#endif
	skb->destructor = sock_wfree;
	skb_set_hash_from_sk(skb, sk);
	/*
	 * We used to take a refcount on sk, but following operation
	 * is enough to guarantee sk_free() wont free this sock until
	 * all in-flight packets are completed
	 */
	atomic_add(skb->truesize, &sk->sk_wmem_alloc);
}
EXPORT_SYMBOL(skb_set_owner_w);

/* This helper is used by netem, as it can hold packets in its
 * delay queue. We want to allow the owner socket to send more
 * packets, as if they were already TX completed by a typical driver.
 * But we also want to keep skb->sk set because some packet schedulers
 * rely on it (sch_fq for example). So we set skb->truesize to a small
 * amount (1) and decrease sk_wmem_alloc accordingly.
 */
void skb_orphan_partial(struct sk_buff *skb)
{
	/* If this skb is a TCP pure ACK or already went here,
	 * we have nothing to do. 2 is already a very small truesize.
	 */
	if (skb->truesize <= 2)
		return;

	/* 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);

/*
 * Buffer destructor for skbs that are not used directly in read or write
 * path, e.g. for error handler skbs. Automatically called from kfree_skb.
 */
void sock_efree(struct sk_buff *skb)
{
	sock_put(skb->sk);
}
EXPORT_SYMBOL(sock_efree);

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 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. Note, we actually want the inline
 * here as this allows gcc to detect the nullify and fold away the
 * condition entirely.
 */
static inline void __sock_kfree_s(struct sock *sk, void *mem, int size,
				  const bool nullify)
{
	if (WARN_ON_ONCE(!mem))
		return;
	if (nullify)
		kzfree(mem);
	else
		kfree(mem);
	atomic_sub(size, &sk->sk_omem_alloc);
}

void sock_kfree_s(struct sock *sk, void *mem, int size)
{
	__sock_kfree_s(sk, mem, size, false);
}
EXPORT_SYMBOL(sock_kfree_s);

void sock_kzfree_s(struct sock *sk, void *mem, int size)
{
	__sock_kfree_s(sk, mem, size, true);
}
EXPORT_SYMBOL(sock_kzfree_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);

	sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
	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;
	long timeo;
	int err;

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

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

		if (sk_wmem_alloc_get(sk) < sk->sk_sndbuf)
			break;

		sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
		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);
	}
	skb = alloc_skb_with_frags(header_len, data_len, max_page_order,
				   errcode, sk->sk_allocation);
	if (skb)
		skb_set_owner_w(skb, sk);
	return skb;

interrupted:
	err = sock_intr_errno(timeo);
failure:
	*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);

int __sock_cmsg_send(struct sock *sk, struct msghdr *msg, struct cmsghdr *cmsg,
		     struct sockcm_cookie *sockc)
{
	u32 tsflags;

	switch (cmsg->cmsg_type) {
	case SO_MARK:
		if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
			return -EPERM;
		if (cmsg->cmsg_len != CMSG_LEN(sizeof(u32)))
			return -EINVAL;
		sockc->mark = *(u32 *)CMSG_DATA(cmsg);
		break;
	case SO_TIMESTAMPING:
		if (cmsg->cmsg_len != CMSG_LEN(sizeof(u32)))
			return -EINVAL;

		tsflags = *(u32 *)CMSG_DATA(cmsg);
		if (tsflags & ~SOF_TIMESTAMPING_TX_RECORD_MASK)
			return -EINVAL;

		sockc->tsflags &= ~SOF_TIMESTAMPING_TX_RECORD_MASK;
		sockc->tsflags |= tsflags;
		break;
	/* SCM_RIGHTS and SCM_CREDENTIALS are semantically in SOL_UNIX. */
	case SCM_RIGHTS:
	case SCM_CREDENTIALS:
		break;
	default:
		return -EINVAL;
	}
	return 0;
}
EXPORT_SYMBOL(__sock_cmsg_send);

int sock_cmsg_send(struct sock *sk, struct msghdr *msg,
		   struct sockcm_cookie *sockc)
{
	struct cmsghdr *cmsg;
	int ret;

	for_each_cmsghdr(cmsg, msg) {
		if (!CMSG_OK(msg, cmsg))
			return -EINVAL;
		if (cmsg->cmsg_level != SOL_SOCKET)
			continue;
		ret = __sock_cmsg_send(sk, msg, cmsg, sockc);
		if (ret)
			return ret;
	}
	return 0;
}
EXPORT_SYMBOL(sock_cmsg_send);

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

/**
 * skb_page_frag_refill - check that a page_frag contains enough room
 * @sz: minimum size of the fragment we want to get
 * @pfrag: pointer to page_frag
 * @gfp: priority for memory allocation
 *
 * Note: While this allocator tries to use high order pages, there is
 * no guarantee that allocations succeed. Therefore, @sz MUST be
 * less or equal than PAGE_SIZE.
 */
bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t gfp)
{
	if (pfrag->page) {
		if (page_ref_count(pfrag->page) == 1) {
			pfrag->offset = 0;
			return true;
		}
		if (pfrag->offset + sz <= pfrag->size)
			return true;
		put_page(pfrag->page);
	}

	pfrag->offset = 0;
	if (SKB_FRAG_PAGE_ORDER) {
		/* Avoid direct reclaim but allow kswapd to wake */
		pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) |
					  __GFP_COMP | __GFP_NOWARN |
					  __GFP_NORETRY,
					  SKB_FRAG_PAGE_ORDER);
		if (likely(pfrag->page)) {
			pfrag->size = PAGE_SIZE << SKB_FRAG_PAGE_ORDER;
			return true;
		}
	}
	pfrag->page = alloc_page(gfp);
	if (likely(pfrag->page)) {
		pfrag->size = PAGE_SIZE;
		return true;
	}
	return false;
}
EXPORT_SYMBOL(skb_page_frag_refill);

bool sk_page_frag_refill(struct sock *sk, struct page_frag *pfrag)
{
	if (likely(skb_page_frag_refill(32U, pfrag, sk->sk_allocation)))
		return true;

	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, *next;

	while ((skb = sk->sk_backlog.head) != NULL) {
		sk->sk_backlog.head = sk->sk_backlog.tail = NULL;

		spin_unlock_bh(&sk->sk_lock.slock);

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

			cond_resched();

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

		spin_lock_bh(&sk->sk_lock.slock);
	}

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

void __sk_flush_backlog(struct sock *sk)
{
	spin_lock_bh(&sk->sk_lock.slock);
	__release_sock(sk);
	spin_unlock_bh(&sk->sk_lock.slock);
}

/**
 * sk_wait_data - wait for data to arrive at sk_receive_queue
 * @sk:    sock to wait on
 * @timeo: for how long
 * @skb:   last skb seen on sk_receive_queue
 *
 * 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, const struct sk_buff *skb)
{
	DEFINE_WAIT_FUNC(wait, woken_wake_function);
	int rc;

	add_wait_queue(sk_sleep(sk), &wait);
	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
	rc = sk_wait_event(sk, timeo, skb_peek_tail(&sk->sk_receive_queue) != skb, &wait);
	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
	remove_wait_queue(sk_sleep(sk), &wait);
	return rc;
}
EXPORT_SYMBOL(sk_wait_data);

/**
 *	__sk_mem_raise_allocated - increase memory_allocated
 *	@sk: socket
 *	@size: memory size to allocate
 *	@amt: pages to allocate
 *	@kind: allocation type
 *
 *	Similar to __sk_mem_schedule(), but does not update sk_forward_alloc
 */
int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind)
{
	struct proto *prot = sk->sk_prot;
	long allocated = sk_memory_allocated_add(sk, amt);

	if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
	    !mem_cgroup_charge_skmem(sk->sk_memcg, amt))
		goto suppress_allocation;

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

	/* Under pressure. */
	if (allocated > sk_prot_mem_limits(sk, 1))
		sk_enter_memory_pressure(sk);

	/* Over hard limit. */
	if (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);

	sk_memory_allocated_sub(sk, amt);

	if (mem_cgroup_sockets_enabled && sk->sk_memcg)
		mem_cgroup_uncharge_skmem(sk->sk_memcg, amt);

	return 0;
}
EXPORT_SYMBOL(__sk_mem_raise_allocated);

/**
 *	__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)
{
	int ret, amt = sk_mem_pages(size);

	sk->sk_forward_alloc += amt << SK_MEM_QUANTUM_SHIFT;
	ret = __sk_mem_raise_allocated(sk, size, amt, kind);
	if (!ret)
		sk->sk_forward_alloc -= amt << SK_MEM_QUANTUM_SHIFT;
	return ret;
}
EXPORT_SYMBOL(__sk_mem_schedule);

/**
 *	__sk_mem_reduce_allocated - reclaim memory_allocated
 *	@sk: socket
 *	@amount: number of quanta
 *
 *	Similar to __sk_mem_reclaim(), but does not update sk_forward_alloc
 */
void __sk_mem_reduce_allocated(struct sock *sk, int amount)
{
	sk_memory_allocated_sub(sk, amount);

	if (mem_cgroup_sockets_enabled && sk->sk_memcg)
		mem_cgroup_uncharge_skmem(sk->sk_memcg, amount);

	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_reduce_allocated);

/**
 *	__sk_mem_reclaim - reclaim sk_forward_alloc and memory_allocated
 *	@sk: socket
 *	@amount: number of bytes (rounded down to a SK_MEM_QUANTUM multiple)
 */
void __sk_mem_reclaim(struct sock *sk, int amount)
{
	amount >>= SK_MEM_QUANTUM_SHIFT;
	sk->sk_forward_alloc -= amount << SK_MEM_QUANTUM_SHIFT;
	__sk_mem_reduce_allocated(sk, amount);
}
EXPORT_SYMBOL(__sk_mem_reclaim);

int sk_set_peek_off(struct sock *sk, int val)
{
	if (val < 0)
		return -EINVAL;

	sk->sk_peek_off = val;
	return 0;
}
EXPORT_SYMBOL_GPL(sk_set_peek_off);

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

int sock_no_recvmsg(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 (skwq_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 (skwq_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)
{
	struct socket_wq *wq;

	rcu_read_lock();
	wq = rcu_dereference(sk->sk_wq);
	if (skwq_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 (skwq_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)
{
}

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);

	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;
		sk->sk_uid	=	SOCK_INODE(sock)->i_uid;
	} else {
		sk->sk_wq	=	NULL;
		sk->sk_uid	=	make_kuid(sock_net(sk)->user_ns, 0);
	}

	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_max_pacing_rate = ~0U;
	sk->sk_pacing_rate = ~0U;
	sk->sk_incoming_cpu = -1;
	/*
	 * 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)
{
	spin_lock_bh(&sk->sk_lock.slock);
	if (sk->sk_backlog.tail)
		__release_sock(sk);

	/* Warning : release_cb() might need to release sk ownership,
	 * ie call sock_release_ownership(sk) before us.
	 */
	if (sk->sk_prot->release_cb)
		sk->sk_prot->release_cb(sk);

	sock_release_ownership(sk);
	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 (sock_needs_netstamp(sk) &&
		    !(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;
	int copied, err;

	err = -EAGAIN;
	skb = sock_dequeue_err_skb(sk);
	if (skb == NULL)
		goto out;

	copied = skb->len;
	if (copied > len) {
		msg->msg_flags |= MSG_TRUNC;
		copied = len;
	}
	err = skb_copy_datagram_msg(skb, 0, msg, 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;

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 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(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

static void req_prot_cleanup(struct request_sock_ops *rsk_prot)
{
	if (!rsk_prot)
		return;
	kfree(rsk_prot->slab_name);
	rsk_prot->slab_name = NULL;
	kmem_cache_destroy(rsk_prot->slab);
	rsk_prot->slab = NULL;
}

static int req_prot_init(const struct proto *prot)
{
	struct request_sock_ops *rsk_prot = prot->rsk_prot;

	if (!rsk_prot)
		return 0;

	rsk_prot->slab_name = kasprintf(GFP_KERNEL, "request_sock_%s",
					prot->name);
	if (!rsk_prot->slab_name)
		return -ENOMEM;

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

	if (!rsk_prot->slab) {
		pr_crit("%s: Can't create request sock SLAB cache!\n",
			prot->name);
		return -ENOMEM;
	}
	return 0;
}

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 (req_prot_init(prot))
			goto out_free_request_sock_slab;

		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,
						  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:
	req_prot_cleanup(prot->rsk_prot);

	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);

	kmem_cache_destroy(prot->slab);
	prot->slab = NULL;

	req_prot_cleanup(prot->rsk_prot);

	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 */