// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   * 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.
   *
   *		"Ping" sockets
   *

   * Based on ipv4/udp.c code.
   *
   * Authors:	Vasiliy Kulikov / Openwall (for Linux 2.6),
   *		Pavel Kankovsky (for Linux 2.4.32)
   *
   * Pavel gave all rights to bugs to Vasiliy,
   * none of the bugs are Pavel's now.

   */

  #include <linux/uaccess.h>

  #include <linux/types.h>
  #include <linux/fcntl.h>
  #include <linux/socket.h>
  #include <linux/sockios.h>
  #include <linux/in.h>
  #include <linux/errno.h>
  #include <linux/timer.h>
  #include <linux/mm.h>
  #include <linux/inet.h>
  #include <linux/netdevice.h>
  #include <net/snmp.h>
  #include <net/ip.h>

  #include <net/icmp.h>
  #include <net/protocol.h>
  #include <linux/skbuff.h>
  #include <linux/proc_fs.h>

  #include <linux/export.h>

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

  #include <net/udp.h>
  #include <net/route.h>
  #include <net/inet_common.h>
  #include <net/checksum.h>

  #if IS_ENABLED(CONFIG_IPV6)
  #include <linux/in6.h>
  #include <linux/icmpv6.h>
  #include <net/addrconf.h>
  #include <net/ipv6.h>
  #include <net/transp_v6.h>
  #endif

  struct ping_table {
  	struct hlist_nulls_head	hash[PING_HTABLE_SIZE];
  	rwlock_t		lock;
  };

  static struct ping_table ping_table;

  struct pingv6_ops pingv6_ops;
  EXPORT_SYMBOL_GPL(pingv6_ops);

  static u16 ping_port_rover;

  static inline u32 ping_hashfn(const struct net *net, u32 num, u32 mask)

  {

  	u32 res = (num + net_hash_mix(net)) & mask;

  	pr_debug("hash(%u) = %u
  ", num, res);

  	return res;
  }

  EXPORT_SYMBOL_GPL(ping_hash);

  
  static inline struct hlist_nulls_head *ping_hashslot(struct ping_table *table,

  					     struct net *net, unsigned int num)

  {
  	return &table->hash[ping_hashfn(net, num, PING_HTABLE_MASK)];
  }

  int ping_get_port(struct sock *sk, unsigned short ident)

  {
  	struct hlist_nulls_node *node;
  	struct hlist_nulls_head *hlist;
  	struct inet_sock *isk, *isk2;
  	struct sock *sk2 = NULL;
  
  	isk = inet_sk(sk);
  	write_lock_bh(&ping_table.lock);
  	if (ident == 0) {
  		u32 i;
  		u16 result = ping_port_rover + 1;
  
  		for (i = 0; i < (1L << 16); i++, result++) {
  			if (!result)
  				result++; /* avoid zero */
  			hlist = ping_hashslot(&ping_table, sock_net(sk),
  					    result);
  			ping_portaddr_for_each_entry(sk2, node, hlist) {
  				isk2 = inet_sk(sk2);
  
  				if (isk2->inet_num == result)
  					goto next_port;
  			}
  
  			/* found */
  			ping_port_rover = ident = result;
  			break;
  next_port:
  			;
  		}
  		if (i >= (1L << 16))
  			goto fail;
  	} else {
  		hlist = ping_hashslot(&ping_table, sock_net(sk), ident);
  		ping_portaddr_for_each_entry(sk2, node, hlist) {
  			isk2 = inet_sk(sk2);

  			/* BUG? Why is this reuse and not reuseaddr? ping.c
  			 * doesn't turn off SO_REUSEADDR, and it doesn't expect
  			 * that other ping processes can steal its packets.
  			 */

  			if ((isk2->inet_num == ident) &&
  			    (sk2 != sk) &&
  			    (!sk2->sk_reuse || !sk->sk_reuse))
  				goto fail;
  		}
  	}
  
  	pr_debug("found port/ident = %d
  ", ident);
  	isk->inet_num = ident;
  	if (sk_unhashed(sk)) {
  		pr_debug("was not hashed
  ");
  		sock_hold(sk);
  		hlist_nulls_add_head(&sk->sk_nulls_node, hlist);
  		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
  	}
  	write_unlock_bh(&ping_table.lock);
  	return 0;
  
  fail:
  	write_unlock_bh(&ping_table.lock);
  	return 1;
  }

  EXPORT_SYMBOL_GPL(ping_get_port);

  int ping_hash(struct sock *sk)

  {

  	pr_debug("ping_hash(sk->port=%u)
  ", inet_sk(sk)->inet_num);

  	BUG(); /* "Please do not press this button again." */

  
  	return 0;

  }

  void ping_unhash(struct sock *sk)

  {
  	struct inet_sock *isk = inet_sk(sk);

  	pr_debug("ping_unhash(isk=%p,isk->num=%u)
  ", isk, isk->inet_num);

  	write_lock_bh(&ping_table.lock);

  	if (sk_hashed(sk)) {

  		hlist_nulls_del(&sk->sk_nulls_node);

  		sk_nulls_node_init(&sk->sk_nulls_node);

  		sock_put(sk);

  		isk->inet_num = 0;
  		isk->inet_sport = 0;

  		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);

  	}

  	write_unlock_bh(&ping_table.lock);

  }

  EXPORT_SYMBOL_GPL(ping_unhash);

  static struct sock *ping_lookup(struct net *net, struct sk_buff *skb, u16 ident)

  {
  	struct hlist_nulls_head *hslot = ping_hashslot(&ping_table, net, ident);
  	struct sock *sk = NULL;
  	struct inet_sock *isk;
  	struct hlist_nulls_node *hnode;

  	int dif = skb->dev->ifindex;
  
  	if (skb->protocol == htons(ETH_P_IP)) {
  		pr_debug("try to find: num = %d, daddr = %pI4, dif = %d
  ",
  			 (int)ident, &ip_hdr(skb)->daddr, dif);
  #if IS_ENABLED(CONFIG_IPV6)
  	} else if (skb->protocol == htons(ETH_P_IPV6)) {
  		pr_debug("try to find: num = %d, daddr = %pI6c, dif = %d
  ",
  			 (int)ident, &ipv6_hdr(skb)->daddr, dif);
  #endif
  	}

  	read_lock_bh(&ping_table.lock);
  
  	ping_portaddr_for_each_entry(sk, hnode, hslot) {
  		isk = inet_sk(sk);

  		pr_debug("iterate
  ");
  		if (isk->inet_num != ident)
  			continue;

  
  		if (skb->protocol == htons(ETH_P_IP) &&
  		    sk->sk_family == AF_INET) {
  			pr_debug("found: %p: num=%d, daddr=%pI4, dif=%d
  ", sk,
  				 (int) isk->inet_num, &isk->inet_rcv_saddr,
  				 sk->sk_bound_dev_if);
  
  			if (isk->inet_rcv_saddr &&
  			    isk->inet_rcv_saddr != ip_hdr(skb)->daddr)
  				continue;
  #if IS_ENABLED(CONFIG_IPV6)
  		} else if (skb->protocol == htons(ETH_P_IPV6) &&
  			   sk->sk_family == AF_INET6) {

  
  			pr_debug("found: %p: num=%d, daddr=%pI6c, dif=%d
  ", sk,
  				 (int) isk->inet_num,

  				 &sk->sk_v6_rcv_saddr,

  				 sk->sk_bound_dev_if);

  			if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr) &&
  			    !ipv6_addr_equal(&sk->sk_v6_rcv_saddr,

  					     &ipv6_hdr(skb)->daddr))
  				continue;
  #endif

  		} else {
  			continue;

  		}

  		if (sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif)
  			continue;
  
  		sock_hold(sk);
  		goto exit;
  	}
  
  	sk = NULL;
  exit:
  	read_unlock_bh(&ping_table.lock);
  
  	return sk;
  }

  static void inet_get_ping_group_range_net(struct net *net, kgid_t *low,
  					  kgid_t *high)

  {

  	kgid_t *data = net->ipv4.ping_group_range.range;

  	unsigned int seq;

  	do {

  		seq = read_seqbegin(&net->ipv4.ping_group_range.lock);

  
  		*low = data[0];
  		*high = data[1];

  	} while (read_seqretry(&net->ipv4.ping_group_range.lock, seq));

  }

  int ping_init_sock(struct sock *sk)

  {
  	struct net *net = sock_net(sk);

  	kgid_t group = current_egid();

  	struct group_info *group_info;

  	int i;

  	kgid_t low, high;

  	int ret = 0;

  	if (sk->sk_family == AF_INET6)
  		sk->sk_ipv6only = 1;

  	inet_get_ping_group_range_net(net, &low, &high);
  	if (gid_lte(low, group) && gid_lte(group, high))

  		return 0;

  	group_info = get_current_groups();

  	for (i = 0; i < group_info->ngroups; i++) {
  		kgid_t gid = group_info->gid[i];

  		if (gid_lte(low, gid) && gid_lte(gid, high))
  			goto out_release_group;

  	}

  	ret = -EACCES;
  
  out_release_group:
  	put_group_info(group_info);
  	return ret;

  }

  EXPORT_SYMBOL_GPL(ping_init_sock);

  void ping_close(struct sock *sk, long timeout)

  {
  	pr_debug("ping_close(sk=%p,sk->num=%u)
  ",

  		 inet_sk(sk), inet_sk(sk)->inet_num);

  	pr_debug("isk->refcnt = %d
  ", refcount_read(&sk->sk_refcnt));

  
  	sk_common_release(sk);
  }

  EXPORT_SYMBOL_GPL(ping_close);
  
  /* Checks the bind address and possibly modifies sk->sk_bound_dev_if. */

  static int ping_check_bind_addr(struct sock *sk, struct inet_sock *isk,

  				struct sockaddr *uaddr, int addr_len)
  {

  	struct net *net = sock_net(sk);
  	if (sk->sk_family == AF_INET) {
  		struct sockaddr_in *addr = (struct sockaddr_in *) uaddr;
  		int chk_addr_ret;
  
  		if (addr_len < sizeof(*addr))
  			return -EINVAL;

  		if (addr->sin_family != AF_INET &&
  		    !(addr->sin_family == AF_UNSPEC &&
  		      addr->sin_addr.s_addr == htonl(INADDR_ANY)))
  			return -EAFNOSUPPORT;

  		pr_debug("ping_check_bind_addr(sk=%p,addr=%pI4,port=%d)
  ",
  			 sk, &addr->sin_addr.s_addr, ntohs(addr->sin_port));

  		if (addr->sin_addr.s_addr == htonl(INADDR_ANY))
  			chk_addr_ret = RTN_LOCAL;

  		else
  			chk_addr_ret = inet_addr_type(net, addr->sin_addr.s_addr);

  		if ((!inet_can_nonlocal_bind(net, isk) &&

  		     chk_addr_ret != RTN_LOCAL) ||
  		    chk_addr_ret == RTN_MULTICAST ||
  		    chk_addr_ret == RTN_BROADCAST)
  			return -EADDRNOTAVAIL;
  
  #if IS_ENABLED(CONFIG_IPV6)
  	} else if (sk->sk_family == AF_INET6) {
  		struct sockaddr_in6 *addr = (struct sockaddr_in6 *) uaddr;
  		int addr_type, scoped, has_addr;
  		struct net_device *dev = NULL;
  
  		if (addr_len < sizeof(*addr))
  			return -EINVAL;

  		if (addr->sin6_family != AF_INET6)

  			return -EAFNOSUPPORT;

  		pr_debug("ping_check_bind_addr(sk=%p,addr=%pI6c,port=%d)
  ",
  			 sk, addr->sin6_addr.s6_addr, ntohs(addr->sin6_port));
  
  		addr_type = ipv6_addr_type(&addr->sin6_addr);
  		scoped = __ipv6_addr_needs_scope_id(addr_type);
  		if ((addr_type != IPV6_ADDR_ANY &&
  		     !(addr_type & IPV6_ADDR_UNICAST)) ||
  		    (scoped && !addr->sin6_scope_id))
  			return -EINVAL;
  
  		rcu_read_lock();
  		if (addr->sin6_scope_id) {
  			dev = dev_get_by_index_rcu(net, addr->sin6_scope_id);
  			if (!dev) {
  				rcu_read_unlock();
  				return -ENODEV;
  			}
  		}
  		has_addr = pingv6_ops.ipv6_chk_addr(net, &addr->sin6_addr, dev,
  						    scoped);
  		rcu_read_unlock();

  		if (!(ipv6_can_nonlocal_bind(net, isk) || has_addr ||

  		      addr_type == IPV6_ADDR_ANY))
  			return -EADDRNOTAVAIL;
  
  		if (scoped)
  			sk->sk_bound_dev_if = addr->sin6_scope_id;
  #endif
  	} else {
  		return -EAFNOSUPPORT;
  	}
  	return 0;
  }

  static void ping_set_saddr(struct sock *sk, struct sockaddr *saddr)

  {
  	if (saddr->sa_family == AF_INET) {
  		struct inet_sock *isk = inet_sk(sk);
  		struct sockaddr_in *addr = (struct sockaddr_in *) saddr;
  		isk->inet_rcv_saddr = isk->inet_saddr = addr->sin_addr.s_addr;
  #if IS_ENABLED(CONFIG_IPV6)
  	} else if (saddr->sa_family == AF_INET6) {
  		struct sockaddr_in6 *addr = (struct sockaddr_in6 *) saddr;
  		struct ipv6_pinfo *np = inet6_sk(sk);

  		sk->sk_v6_rcv_saddr = np->saddr = addr->sin6_addr;

  #endif
  	}
  }

  
  /*
   * We need our own bind because there are no privileged id's == local ports.
   * Moreover, we don't allow binding to multi- and broadcast addresses.
   */

  int ping_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)

  {

  	struct inet_sock *isk = inet_sk(sk);
  	unsigned short snum;

  	int err;

  	int dif = sk->sk_bound_dev_if;

  	err = ping_check_bind_addr(sk, isk, uaddr, addr_len);
  	if (err)
  		return err;

  
  	lock_sock(sk);
  
  	err = -EINVAL;
  	if (isk->inet_num != 0)
  		goto out;
  
  	err = -EADDRINUSE;

  	snum = ntohs(((struct sockaddr_in *)uaddr)->sin_port);
  	if (ping_get_port(sk, snum) != 0) {

  		/* Restore possibly modified sk->sk_bound_dev_if by ping_check_bind_addr(). */
  		sk->sk_bound_dev_if = dif;

  		goto out;
  	}

  	ping_set_saddr(sk, uaddr);

  	pr_debug("after bind(): num = %hu, dif = %d
  ",
  		 isk->inet_num,
  		 sk->sk_bound_dev_if);

  
  	err = 0;

  	if (sk->sk_family == AF_INET && isk->inet_rcv_saddr)

  		sk->sk_userlocks |= SOCK_BINDADDR_LOCK;

  #if IS_ENABLED(CONFIG_IPV6)
  	if (sk->sk_family == AF_INET6 && !ipv6_addr_any(&sk->sk_v6_rcv_saddr))
  		sk->sk_userlocks |= SOCK_BINDADDR_LOCK;
  #endif

  	if (snum)
  		sk->sk_userlocks |= SOCK_BINDPORT_LOCK;
  	isk->inet_sport = htons(isk->inet_num);
  	isk->inet_daddr = 0;
  	isk->inet_dport = 0;

  
  #if IS_ENABLED(CONFIG_IPV6)
  	if (sk->sk_family == AF_INET6)

  		memset(&sk->sk_v6_daddr, 0, sizeof(sk->sk_v6_daddr));

  #endif

  	sk_dst_reset(sk);
  out:
  	release_sock(sk);
  	pr_debug("ping_v4_bind -> %d
  ", err);
  	return err;
  }

  EXPORT_SYMBOL_GPL(ping_bind);

  
  /*
   * Is this a supported type of ICMP message?
   */

  static inline int ping_supported(int family, int type, int code)

  {

  	return (family == AF_INET && type == ICMP_ECHO && code == 0) ||
  	       (family == AF_INET6 && type == ICMPV6_ECHO_REQUEST && code == 0);

  }
  
  /*
   * This routine is called by the ICMP module when it gets some
   * sort of error condition.
   */

  void ping_err(struct sk_buff *skb, int offset, u32 info)

  {

  	int family;
  	struct icmphdr *icmph;

  	struct inet_sock *inet_sock;

  	int type;
  	int code;

  	struct net *net = dev_net(skb->dev);
  	struct sock *sk;
  	int harderr;
  	int err;

  	if (skb->protocol == htons(ETH_P_IP)) {
  		family = AF_INET;
  		type = icmp_hdr(skb)->type;
  		code = icmp_hdr(skb)->code;
  		icmph = (struct icmphdr *)(skb->data + offset);
  	} else if (skb->protocol == htons(ETH_P_IPV6)) {
  		family = AF_INET6;
  		type = icmp6_hdr(skb)->icmp6_type;
  		code = icmp6_hdr(skb)->icmp6_code;
  		icmph = (struct icmphdr *) (skb->data + offset);
  	} else {
  		BUG();
  	}

  	/* We assume the packet has already been checked by icmp_unreach */

  	if (!ping_supported(family, icmph->type, icmph->code))

  		return;

  	pr_debug("ping_err(proto=0x%x,type=%d,code=%d,id=%04x,seq=%04x)
  ",
  		 skb->protocol, type, code, ntohs(icmph->un.echo.id),
  		 ntohs(icmph->un.echo.sequence));

  	sk = ping_lookup(net, skb, ntohs(icmph->un.echo.id));

  	if (!sk) {

  		pr_debug("no socket, dropping
  ");
  		return;	/* No socket for error */
  	}
  	pr_debug("err on socket %p
  ", sk);
  
  	err = 0;
  	harderr = 0;
  	inet_sock = inet_sk(sk);

  	if (skb->protocol == htons(ETH_P_IP)) {
  		switch (type) {
  		default:
  		case ICMP_TIME_EXCEEDED:
  			err = EHOSTUNREACH;
  			break;
  		case ICMP_SOURCE_QUENCH:
  			/* This is not a real error but ping wants to see it.
  			 * Report it with some fake errno.
  			 */
  			err = EREMOTEIO;
  			break;
  		case ICMP_PARAMETERPROB:
  			err = EPROTO;
  			harderr = 1;
  			break;
  		case ICMP_DEST_UNREACH:
  			if (code == ICMP_FRAG_NEEDED) { /* Path MTU discovery */
  				ipv4_sk_update_pmtu(skb, sk, info);
  				if (inet_sock->pmtudisc != IP_PMTUDISC_DONT) {
  					err = EMSGSIZE;
  					harderr = 1;
  					break;
  				}
  				goto out;

  			}

  			err = EHOSTUNREACH;
  			if (code <= NR_ICMP_UNREACH) {
  				harderr = icmp_err_convert[code].fatal;
  				err = icmp_err_convert[code].errno;
  			}
  			break;
  		case ICMP_REDIRECT:
  			/* See ICMP_SOURCE_QUENCH */
  			ipv4_sk_redirect(skb, sk);
  			err = EREMOTEIO;
  			break;

  		}

  #if IS_ENABLED(CONFIG_IPV6)
  	} else if (skb->protocol == htons(ETH_P_IPV6)) {
  		harderr = pingv6_ops.icmpv6_err_convert(type, code, &err);
  #endif

  	}
  
  	/*
  	 *      RFC1122: OK.  Passes ICMP errors back to application, as per
  	 *	4.1.3.3.
  	 */

  	if ((family == AF_INET && !inet_sock->recverr) ||
  	    (family == AF_INET6 && !inet6_sk(sk)->recverr)) {

  		if (!harderr || sk->sk_state != TCP_ESTABLISHED)
  			goto out;
  	} else {

  		if (family == AF_INET) {
  			ip_icmp_error(sk, skb, err, 0 /* no remote port */,
  				      info, (u8 *)icmph);
  #if IS_ENABLED(CONFIG_IPV6)
  		} else if (family == AF_INET6) {
  			pingv6_ops.ipv6_icmp_error(sk, skb, err, 0,
  						   info, (u8 *)icmph);
  #endif
  		}

  	}
  	sk->sk_err = err;
  	sk->sk_error_report(sk);
  out:
  	sock_put(sk);
  }

  EXPORT_SYMBOL_GPL(ping_err);

  
  /*

   *	Copy and checksum an ICMP Echo packet from user space into a buffer
   *	starting from the payload.

   */

  int ping_getfrag(void *from, char *to,
  		 int offset, int fraglen, int odd, struct sk_buff *skb)

  {
  	struct pingfakehdr *pfh = (struct pingfakehdr *)from;
  
  	if (offset == 0) {

  		fraglen -= sizeof(struct icmphdr);
  		if (fraglen < 0)

  			BUG();

  		if (!csum_and_copy_from_iter_full(to + sizeof(struct icmphdr),

  			    fraglen, &pfh->wcheck,

  			    &pfh->msg->msg_iter))

  			return -EFAULT;

  	} else if (offset < sizeof(struct icmphdr)) {
  			BUG();
  	} else {

  		if (!csum_and_copy_from_iter_full(to, fraglen, &pfh->wcheck,
  					    &pfh->msg->msg_iter))

  			return -EFAULT;
  	}

  #if IS_ENABLED(CONFIG_IPV6)
  	/* For IPv6, checksum each skb as we go along, as expected by
  	 * icmpv6_push_pending_frames. For IPv4, accumulate the checksum in
  	 * wcheck, it will be finalized in ping_v4_push_pending_frames.
  	 */
  	if (pfh->family == AF_INET6) {
  		skb->csum = pfh->wcheck;
  		skb->ip_summed = CHECKSUM_NONE;
  		pfh->wcheck = 0;

  	}

  #endif

  	return 0;
  }

  EXPORT_SYMBOL_GPL(ping_getfrag);

  static int ping_v4_push_pending_frames(struct sock *sk, struct pingfakehdr *pfh,
  				       struct flowi4 *fl4)

  {
  	struct sk_buff *skb = skb_peek(&sk->sk_write_queue);

  	if (!skb)
  		return 0;

  	pfh->wcheck = csum_partial((char *)&pfh->icmph,
  		sizeof(struct icmphdr), pfh->wcheck);
  	pfh->icmph.checksum = csum_fold(pfh->wcheck);
  	memcpy(icmp_hdr(skb), &pfh->icmph, sizeof(struct icmphdr));
  	skb->ip_summed = CHECKSUM_NONE;
  	return ip_push_pending_frames(sk, fl4);
  }

  int ping_common_sendmsg(int family, struct msghdr *msg, size_t len,

  			void *user_icmph, size_t icmph_len)
  {

  	u8 type, code;

  
  	if (len > 0xFFFF)
  		return -EMSGSIZE;

  	/* Must have at least a full ICMP header. */
  	if (len < icmph_len)
  		return -EINVAL;

  	/*
  	 *	Check the flags.
  	 */
  
  	/* Mirror BSD error message compatibility */
  	if (msg->msg_flags & MSG_OOB)
  		return -EOPNOTSUPP;
  
  	/*
  	 *	Fetch the ICMP header provided by the userland.

  	 *	iovec is modified! The ICMP header is consumed.

  	 */

  	if (memcpy_from_msg(user_icmph, msg, icmph_len))

  		return -EFAULT;

  
  	if (family == AF_INET) {
  		type = ((struct icmphdr *) user_icmph)->type;
  		code = ((struct icmphdr *) user_icmph)->code;
  #if IS_ENABLED(CONFIG_IPV6)
  	} else if (family == AF_INET6) {
  		type = ((struct icmp6hdr *) user_icmph)->icmp6_type;
  		code = ((struct icmp6hdr *) user_icmph)->icmp6_code;
  #endif
  	} else {
  		BUG();
  	}
  
  	if (!ping_supported(family, type, code))

  		return -EINVAL;

  	return 0;
  }
  EXPORT_SYMBOL_GPL(ping_common_sendmsg);

  static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)

  {
  	struct net *net = sock_net(sk);
  	struct flowi4 fl4;
  	struct inet_sock *inet = inet_sk(sk);
  	struct ipcm_cookie ipc;
  	struct icmphdr user_icmph;
  	struct pingfakehdr pfh;
  	struct rtable *rt = NULL;
  	struct ip_options_data opt_copy;
  	int free = 0;
  	__be32 saddr, daddr, faddr;
  	u8  tos;
  	int err;
  
  	pr_debug("ping_v4_sendmsg(sk=%p,sk->num=%u)
  ", inet, inet->inet_num);
  
  	err = ping_common_sendmsg(AF_INET, msg, len, &user_icmph,
  				  sizeof(user_icmph));
  	if (err)
  		return err;

  	/*
  	 *	Get and verify the address.
  	 */
  
  	if (msg->msg_name) {

  		DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);

  		if (msg->msg_namelen < sizeof(*usin))
  			return -EINVAL;
  		if (usin->sin_family != AF_INET)

  			return -EAFNOSUPPORT;

  		daddr = usin->sin_addr.s_addr;
  		/* no remote port */
  	} else {
  		if (sk->sk_state != TCP_ESTABLISHED)
  			return -EDESTADDRREQ;
  		daddr = inet->inet_daddr;
  		/* no remote port */
  	}

  	ipcm_init_sk(&ipc, inet);

  	if (msg->msg_controllen) {

  		err = ip_cmsg_send(sk, msg, &ipc, false);

  		if (unlikely(err)) {
  			kfree(ipc.opt);

  			return err;

  		}

  		if (ipc.opt)
  			free = 1;
  	}
  	if (!ipc.opt) {
  		struct ip_options_rcu *inet_opt;
  
  		rcu_read_lock();
  		inet_opt = rcu_dereference(inet->inet_opt);
  		if (inet_opt) {
  			memcpy(&opt_copy, inet_opt,
  			       sizeof(*inet_opt) + inet_opt->opt.optlen);
  			ipc.opt = &opt_copy.opt;
  		}
  		rcu_read_unlock();
  	}
  
  	saddr = ipc.addr;
  	ipc.addr = faddr = daddr;
  
  	if (ipc.opt && ipc.opt->opt.srr) {

  		if (!daddr) {
  			err = -EINVAL;
  			goto out_free;
  		}

  		faddr = ipc.opt->opt.faddr;
  	}

  	tos = get_rttos(&ipc, inet);

  	if (sock_flag(sk, SOCK_LOCALROUTE) ||
  	    (msg->msg_flags & MSG_DONTROUTE) ||
  	    (ipc.opt && ipc.opt->opt.is_strictroute)) {
  		tos |= RTO_ONLINK;
  	}
  
  	if (ipv4_is_multicast(daddr)) {

  		if (!ipc.oif || netif_index_is_l3_master(sock_net(sk), ipc.oif))

  			ipc.oif = inet->mc_index;
  		if (!saddr)
  			saddr = inet->mc_addr;

  	} else if (!ipc.oif)
  		ipc.oif = inet->uc_index;

  	flowi4_init_output(&fl4, ipc.oif, ipc.sockc.mark, tos,

  			   RT_SCOPE_UNIVERSE, sk->sk_protocol,

  			   inet_sk_flowi_flags(sk), faddr, saddr, 0, 0,
  			   sk->sk_uid);

  	fl4.fl4_icmp_type = user_icmph.type;
  	fl4.fl4_icmp_code = user_icmph.code;

  	security_sk_classify_flow(sk, flowi4_to_flowi(&fl4));
  	rt = ip_route_output_flow(net, &fl4, sk);
  	if (IS_ERR(rt)) {
  		err = PTR_ERR(rt);
  		rt = NULL;
  		if (err == -ENETUNREACH)

  			IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);

  		goto out;
  	}
  
  	err = -EACCES;
  	if ((rt->rt_flags & RTCF_BROADCAST) &&
  	    !sock_flag(sk, SOCK_BROADCAST))
  		goto out;
  
  	if (msg->msg_flags & MSG_CONFIRM)
  		goto do_confirm;
  back_from_confirm:
  
  	if (!ipc.addr)
  		ipc.addr = fl4.daddr;
  
  	lock_sock(sk);
  
  	pfh.icmph.type = user_icmph.type; /* already checked */
  	pfh.icmph.code = user_icmph.code; /* ditto */
  	pfh.icmph.checksum = 0;
  	pfh.icmph.un.echo.id = inet->inet_sport;
  	pfh.icmph.un.echo.sequence = user_icmph.un.echo.sequence;

  	pfh.msg = msg;

  	pfh.wcheck = 0;

  	pfh.family = AF_INET;

  
  	err = ip_append_data(sk, &fl4, ping_getfrag, &pfh, len,
  			0, &ipc, &rt, msg->msg_flags);
  	if (err)
  		ip_flush_pending_frames(sk);
  	else

  		err = ping_v4_push_pending_frames(sk, &pfh, &fl4);

  	release_sock(sk);
  
  out:
  	ip_rt_put(rt);

  out_free:

  	if (free)
  		kfree(ipc.opt);
  	if (!err) {
  		icmp_out_count(sock_net(sk), user_icmph.type);
  		return len;
  	}
  	return err;
  
  do_confirm:

  	if (msg->msg_flags & MSG_PROBE)
  		dst_confirm_neigh(&rt->dst, &fl4.daddr);

  	if (!(msg->msg_flags & MSG_PROBE) || len)
  		goto back_from_confirm;
  	err = 0;
  	goto out;
  }

  int ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
  		 int flags, int *addr_len)

  {
  	struct inet_sock *isk = inet_sk(sk);

  	int family = sk->sk_family;

  	struct sk_buff *skb;
  	int copied, err;
  
  	pr_debug("ping_recvmsg(sk=%p,sk->num=%u)
  ", isk, isk->inet_num);

  	err = -EOPNOTSUPP;

  	if (flags & MSG_OOB)
  		goto out;

  	if (flags & MSG_ERRQUEUE)
  		return inet_recv_error(sk, msg, len, addr_len);

  
  	skb = skb_recv_datagram(sk, flags, noblock, &err);
  	if (!skb)
  		goto out;
  
  	copied = skb->len;
  	if (copied > len) {
  		msg->msg_flags |= MSG_TRUNC;
  		copied = len;
  	}
  
  	/* Don't bother checking the checksum */

  	err = skb_copy_datagram_msg(skb, 0, msg, copied);

  	if (err)
  		goto done;
  
  	sock_recv_timestamp(msg, sk, skb);

  	/* Copy the address and add cmsg data. */
  	if (family == AF_INET) {

  		DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);

  		if (sin) {
  			sin->sin_family = AF_INET;
  			sin->sin_port = 0 /* skb->h.uh->source */;
  			sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
  			memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
  			*addr_len = sizeof(*sin);
  		}

  
  		if (isk->cmsg_flags)
  			ip_cmsg_recv(msg, skb);
  
  #if IS_ENABLED(CONFIG_IPV6)
  	} else if (family == AF_INET6) {
  		struct ipv6_pinfo *np = inet6_sk(sk);
  		struct ipv6hdr *ip6 = ipv6_hdr(skb);

  		DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);

  		if (sin6) {
  			sin6->sin6_family = AF_INET6;
  			sin6->sin6_port = 0;
  			sin6->sin6_addr = ip6->saddr;
  			sin6->sin6_flowinfo = 0;
  			if (np->sndflow)
  				sin6->sin6_flowinfo = ip6_flowinfo(ip6);
  			sin6->sin6_scope_id =
  				ipv6_iface_scope_id(&sin6->sin6_addr,

  						    inet6_iif(skb));

  			*addr_len = sizeof(*sin6);
  		}

  
  		if (inet6_sk(sk)->rxopt.all)

  			pingv6_ops.ip6_datagram_recv_common_ctl(sk, msg, skb);
  		if (skb->protocol == htons(ETH_P_IPV6) &&
  		    inet6_sk(sk)->rxopt.all)
  			pingv6_ops.ip6_datagram_recv_specific_ctl(sk, msg, skb);
  		else if (skb->protocol == htons(ETH_P_IP) && isk->cmsg_flags)
  			ip_cmsg_recv(msg, skb);

  #endif
  	} else {
  		BUG();

  	}

  	err = copied;
  
  done:
  	skb_free_datagram(sk, skb);
  out:
  	pr_debug("ping_recvmsg -> %d
  ", err);
  	return err;
  }

  EXPORT_SYMBOL_GPL(ping_recvmsg);

  int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)

  {
  	pr_debug("ping_queue_rcv_skb(sk=%p,sk->num=%d,skb=%p)
  ",

  		 inet_sk(sk), inet_sk(sk)->inet_num, skb);

  	if (sock_queue_rcv_skb(sk, skb) < 0) {

  		kfree_skb(skb);
  		pr_debug("ping_queue_rcv_skb -> failed
  ");
  		return -1;
  	}
  	return 0;
  }

  EXPORT_SYMBOL_GPL(ping_queue_rcv_skb);

  
  
  /*
   *	All we need to do is get the socket.
   */

  bool ping_rcv(struct sk_buff *skb)

  {
  	struct sock *sk;
  	struct net *net = dev_net(skb->dev);

  	struct icmphdr *icmph = icmp_hdr(skb);

  
  	/* We assume the packet has already been checked by icmp_rcv */
  
  	pr_debug("ping_rcv(skb=%p,id=%04x,seq=%04x)
  ",

  		 skb, ntohs(icmph->un.echo.id), ntohs(icmph->un.echo.sequence));

  
  	/* Push ICMP header back */
  	skb_push(skb, skb->data - (u8 *)icmph);

  	sk = ping_lookup(net, skb, ntohs(icmph->un.echo.id));

  	if (sk) {

  		struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);

  		pr_debug("rcv on socket %p
  ", sk);

  		if (skb2)
  			ping_queue_rcv_skb(sk, skb2);

  		sock_put(sk);

  		return true;

  	}
  	pr_debug("no socket, dropping
  ");

  	return false;

  }

  EXPORT_SYMBOL_GPL(ping_rcv);

  
  struct proto ping_prot = {
  	.name =		"PING",
  	.owner =	THIS_MODULE,
  	.init =		ping_init_sock,
  	.close =	ping_close,
  	.connect =	ip4_datagram_connect,

  	.disconnect =	__udp_disconnect,

  	.setsockopt =	ip_setsockopt,
  	.getsockopt =	ip_getsockopt,

  	.sendmsg =	ping_v4_sendmsg,

  	.recvmsg =	ping_recvmsg,
  	.bind =		ping_bind,
  	.backlog_rcv =	ping_queue_rcv_skb,

  	.release_cb =	ip4_datagram_release_cb,

  	.hash =		ping_hash,
  	.unhash =	ping_unhash,
  	.get_port =	ping_get_port,

  	.obj_size =	sizeof(struct inet_sock),
  };
  EXPORT_SYMBOL(ping_prot);
  
  #ifdef CONFIG_PROC_FS
  
  static struct sock *ping_get_first(struct seq_file *seq, int start)
  {
  	struct sock *sk;
  	struct ping_iter_state *state = seq->private;
  	struct net *net = seq_file_net(seq);
  
  	for (state->bucket = start; state->bucket < PING_HTABLE_SIZE;
  	     ++state->bucket) {
  		struct hlist_nulls_node *node;

  		struct hlist_nulls_head *hslot;
  
  		hslot = &ping_table.hash[state->bucket];

  
  		if (hlist_nulls_empty(hslot))
  			continue;
  
  		sk_nulls_for_each(sk, node, hslot) {

  			if (net_eq(sock_net(sk), net) &&
  			    sk->sk_family == state->family)

  				goto found;
  		}
  	}
  	sk = NULL;
  found:
  	return sk;
  }
  
  static struct sock *ping_get_next(struct seq_file *seq, struct sock *sk)
  {
  	struct ping_iter_state *state = seq->private;
  	struct net *net = seq_file_net(seq);
  
  	do {
  		sk = sk_nulls_next(sk);
  	} while (sk && (!net_eq(sock_net(sk), net)));
  
  	if (!sk)
  		return ping_get_first(seq, state->bucket + 1);
  	return sk;
  }
  
  static struct sock *ping_get_idx(struct seq_file *seq, loff_t pos)
  {
  	struct sock *sk = ping_get_first(seq, 0);
  
  	if (sk)
  		while (pos && (sk = ping_get_next(seq, sk)) != NULL)
  			--pos;
  	return pos ? NULL : sk;
  }

  void *ping_seq_start(struct seq_file *seq, loff_t *pos, sa_family_t family)

  	__acquires(ping_table.lock)

  {
  	struct ping_iter_state *state = seq->private;
  	state->bucket = 0;

  	state->family = family;

  
  	read_lock_bh(&ping_table.lock);
  
  	return *pos ? ping_get_idx(seq, *pos-1) : SEQ_START_TOKEN;
  }

  EXPORT_SYMBOL_GPL(ping_seq_start);

  static void *ping_v4_seq_start(struct seq_file *seq, loff_t *pos)
  {
  	return ping_seq_start(seq, pos, AF_INET);
  }

  void *ping_seq_next(struct seq_file *seq, void *v, loff_t *pos)

  {
  	struct sock *sk;
  
  	if (v == SEQ_START_TOKEN)
  		sk = ping_get_idx(seq, 0);
  	else
  		sk = ping_get_next(seq, v);
  
  	++*pos;
  	return sk;
  }

  EXPORT_SYMBOL_GPL(ping_seq_next);

  void ping_seq_stop(struct seq_file *seq, void *v)

  	__releases(ping_table.lock)

  {
  	read_unlock_bh(&ping_table.lock);
  }

  EXPORT_SYMBOL_GPL(ping_seq_stop);

  static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,

  		int bucket)

  {
  	struct inet_sock *inet = inet_sk(sp);
  	__be32 dest = inet->inet_daddr;
  	__be32 src = inet->inet_rcv_saddr;
  	__u16 destp = ntohs(inet->inet_dport);
  	__u16 srcp = ntohs(inet->inet_sport);
  
  	seq_printf(f, "%5d: %08X:%04X %08X:%04X"

  		" %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %u",

  		bucket, src, srcp, dest, destp, sp->sk_state,
  		sk_wmem_alloc_get(sp),
  		sk_rmem_alloc_get(sp),

  		0, 0L, 0,
  		from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
  		0, sock_i_ino(sp),

  		refcount_read(&sp->sk_refcnt), sp,

  		atomic_read(&sp->sk_drops));

  }

  static int ping_v4_seq_show(struct seq_file *seq, void *v)

  {

  	seq_setwidth(seq, 127);

  	if (v == SEQ_START_TOKEN)

  		seq_puts(seq, "  sl  local_address rem_address   st tx_queue "

  			   "rx_queue tr tm->when retrnsmt   uid  timeout "
  			   "inode ref pointer drops");
  	else {
  		struct ping_iter_state *state = seq->private;

  		ping_v4_format_sock(v, seq, state->bucket);

  	}

  	seq_pad(seq, '
  ');

  	return 0;
  }

  static const struct seq_operations ping_v4_seq_ops = {
  	.start		= ping_v4_seq_start,
  	.show		= ping_v4_seq_show,
  	.next		= ping_seq_next,
  	.stop		= ping_seq_stop,
  };

  static int __net_init ping_v4_proc_init_net(struct net *net)

  {

  	if (!proc_create_net("icmp", 0444, net->proc_net, &ping_v4_seq_ops,
  			sizeof(struct ping_iter_state)))

  		return -ENOMEM;
  	return 0;

  }

  static void __net_exit ping_v4_proc_exit_net(struct net *net)

  {

  	remove_proc_entry("icmp", net->proc_net);

  }

  static struct pernet_operations ping_v4_net_ops = {
  	.init = ping_v4_proc_init_net,
  	.exit = ping_v4_proc_exit_net,

  };
  
  int __init ping_proc_init(void)
  {

  	return register_pernet_subsys(&ping_v4_net_ops);

  }
  
  void ping_proc_exit(void)
  {

  	unregister_pernet_subsys(&ping_v4_net_ops);

  }
  
  #endif
  
  void __init ping_init(void)
  {
  	int i;
  
  	for (i = 0; i < PING_HTABLE_SIZE; i++)
  		INIT_HLIST_NULLS_HEAD(&ping_table.hash[i], i);
  	rwlock_init(&ping_table.lock);
  }