/* License: GPL */
  
  #include <linux/mutex.h>
  #include <linux/socket.h>
  #include <linux/skbuff.h>
  #include <net/netlink.h>
  #include <net/net_namespace.h>
  #include <linux/module.h>
  #include <net/sock.h>
  #include <linux/kernel.h>
  #include <linux/tcp.h>
  #include <linux/workqueue.h>
  
  #include <linux/inet_diag.h>
  #include <linux/sock_diag.h>
  
  static const struct sock_diag_handler *sock_diag_handlers[AF_MAX];
  static int (*inet_rcv_compat)(struct sk_buff *skb, struct nlmsghdr *nlh);
  static DEFINE_MUTEX(sock_diag_table_mutex);
  static struct workqueue_struct *broadcast_wq;
  
  static u64 sock_gen_cookie(struct sock *sk)
  {
  	while (1) {
  		u64 res = atomic64_read(&sk->sk_cookie);
  
  		if (res)
  			return res;
  		res = atomic64_inc_return(&sock_net(sk)->cookie_gen);
  		atomic64_cmpxchg(&sk->sk_cookie, 0, res);
  	}
  }
  
  int sock_diag_check_cookie(struct sock *sk, const __u32 *cookie)
  {
  	u64 res;
  
  	if (cookie[0] == INET_DIAG_NOCOOKIE && cookie[1] == INET_DIAG_NOCOOKIE)
  		return 0;
  
  	res = sock_gen_cookie(sk);
  	if ((u32)res != cookie[0] || (u32)(res >> 32) != cookie[1])
  		return -ESTALE;
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(sock_diag_check_cookie);
  
  void sock_diag_save_cookie(struct sock *sk, __u32 *cookie)
  {
  	u64 res = sock_gen_cookie(sk);
  
  	cookie[0] = (u32)res;
  	cookie[1] = (u32)(res >> 32);
  }
  EXPORT_SYMBOL_GPL(sock_diag_save_cookie);
  
  int sock_diag_put_meminfo(struct sock *sk, struct sk_buff *skb, int attrtype)
  {
  	u32 mem[SK_MEMINFO_VARS];
  
  	mem[SK_MEMINFO_RMEM_ALLOC] = sk_rmem_alloc_get(sk);
  	mem[SK_MEMINFO_RCVBUF] = sk->sk_rcvbuf;
  	mem[SK_MEMINFO_WMEM_ALLOC] = sk_wmem_alloc_get(sk);
  	mem[SK_MEMINFO_SNDBUF] = sk->sk_sndbuf;
  	mem[SK_MEMINFO_FWD_ALLOC] = sk->sk_forward_alloc;
  	mem[SK_MEMINFO_WMEM_QUEUED] = sk->sk_wmem_queued;
  	mem[SK_MEMINFO_OPTMEM] = atomic_read(&sk->sk_omem_alloc);
  	mem[SK_MEMINFO_BACKLOG] = sk->sk_backlog.len;
  
  	return nla_put(skb, attrtype, sizeof(mem), &mem);
  }
  EXPORT_SYMBOL_GPL(sock_diag_put_meminfo);
  
  int sock_diag_put_filterinfo(bool may_report_filterinfo, struct sock *sk,
  			     struct sk_buff *skb, int attrtype)
  {
  	struct sock_fprog_kern *fprog;
  	struct sk_filter *filter;
  	struct nlattr *attr;
  	unsigned int flen;
  	int err = 0;
  
  	if (!may_report_filterinfo) {
  		nla_reserve(skb, attrtype, 0);
  		return 0;
  	}
  
  	rcu_read_lock();
  	filter = rcu_dereference(sk->sk_filter);
  	if (!filter)
  		goto out;
  
  	fprog = filter->prog->orig_prog;
  	if (!fprog)
  		goto out;
  
  	flen = bpf_classic_proglen(fprog);
  
  	attr = nla_reserve(skb, attrtype, flen);
  	if (attr == NULL) {
  		err = -EMSGSIZE;
  		goto out;
  	}
  
  	memcpy(nla_data(attr), fprog->filter, flen);
  out:
  	rcu_read_unlock();
  	return err;
  }
  EXPORT_SYMBOL(sock_diag_put_filterinfo);
  
  struct broadcast_sk {
  	struct sock *sk;
  	struct work_struct work;
  };
  
  static size_t sock_diag_nlmsg_size(void)
  {
  	return NLMSG_ALIGN(sizeof(struct inet_diag_msg)
  	       + nla_total_size(sizeof(u8)) /* INET_DIAG_PROTOCOL */
  	       + nla_total_size(sizeof(struct tcp_info))); /* INET_DIAG_INFO */
  }
  
  static void sock_diag_broadcast_destroy_work(struct work_struct *work)
  {
  	struct broadcast_sk *bsk =
  		container_of(work, struct broadcast_sk, work);
  	struct sock *sk = bsk->sk;
  	const struct sock_diag_handler *hndl;
  	struct sk_buff *skb;
  	const enum sknetlink_groups group = sock_diag_destroy_group(sk);
  	int err = -1;
  
  	WARN_ON(group == SKNLGRP_NONE);
  
  	skb = nlmsg_new(sock_diag_nlmsg_size(), GFP_KERNEL);
  	if (!skb)
  		goto out;
  
  	mutex_lock(&sock_diag_table_mutex);
  	hndl = sock_diag_handlers[sk->sk_family];
  	if (hndl && hndl->get_info)
  		err = hndl->get_info(skb, sk);
  	mutex_unlock(&sock_diag_table_mutex);
  
  	if (!err)
  		nlmsg_multicast(sock_net(sk)->diag_nlsk, skb, 0, group,
  				GFP_KERNEL);
  	else
  		kfree_skb(skb);
  out:
  	sk_destruct(sk);
  	kfree(bsk);
  }
  
  void sock_diag_broadcast_destroy(struct sock *sk)
  {
  	/* Note, this function is often called from an interrupt context. */
  	struct broadcast_sk *bsk =
  		kmalloc(sizeof(struct broadcast_sk), GFP_ATOMIC);
  	if (!bsk)
  		return sk_destruct(sk);
  	bsk->sk = sk;
  	INIT_WORK(&bsk->work, sock_diag_broadcast_destroy_work);
  	queue_work(broadcast_wq, &bsk->work);
  }
  
  void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh))
  {
  	mutex_lock(&sock_diag_table_mutex);
  	inet_rcv_compat = fn;
  	mutex_unlock(&sock_diag_table_mutex);
  }
  EXPORT_SYMBOL_GPL(sock_diag_register_inet_compat);
  
  void sock_diag_unregister_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh))
  {
  	mutex_lock(&sock_diag_table_mutex);
  	inet_rcv_compat = NULL;
  	mutex_unlock(&sock_diag_table_mutex);
  }
  EXPORT_SYMBOL_GPL(sock_diag_unregister_inet_compat);
  
  int sock_diag_register(const struct sock_diag_handler *hndl)
  {
  	int err = 0;
  
  	if (hndl->family >= AF_MAX)
  		return -EINVAL;
  
  	mutex_lock(&sock_diag_table_mutex);
  	if (sock_diag_handlers[hndl->family])
  		err = -EBUSY;
  	else
  		sock_diag_handlers[hndl->family] = hndl;
  	mutex_unlock(&sock_diag_table_mutex);
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(sock_diag_register);
  
  void sock_diag_unregister(const struct sock_diag_handler *hnld)
  {
  	int family = hnld->family;
  
  	if (family >= AF_MAX)
  		return;
  
  	mutex_lock(&sock_diag_table_mutex);
  	BUG_ON(sock_diag_handlers[family] != hnld);
  	sock_diag_handlers[family] = NULL;
  	mutex_unlock(&sock_diag_table_mutex);
  }
  EXPORT_SYMBOL_GPL(sock_diag_unregister);
  
  static int __sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
  {
  	int err;
  	struct sock_diag_req *req = nlmsg_data(nlh);
  	const struct sock_diag_handler *hndl;
  
  	if (nlmsg_len(nlh) < sizeof(*req))
  		return -EINVAL;
  
  	if (req->sdiag_family >= AF_MAX)
  		return -EINVAL;
  
  	if (sock_diag_handlers[req->sdiag_family] == NULL)
  		request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
  				NETLINK_SOCK_DIAG, req->sdiag_family);
  
  	mutex_lock(&sock_diag_table_mutex);
  	hndl = sock_diag_handlers[req->sdiag_family];
  	if (hndl == NULL)
  		err = -ENOENT;
  	else
  		err = hndl->dump(skb, nlh);
  	mutex_unlock(&sock_diag_table_mutex);
  
  	return err;
  }
  
  static int sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
  {
  	int ret;
  
  	switch (nlh->nlmsg_type) {
  	case TCPDIAG_GETSOCK:
  	case DCCPDIAG_GETSOCK:
  		if (inet_rcv_compat == NULL)
  			request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
  					NETLINK_SOCK_DIAG, AF_INET);
  
  		mutex_lock(&sock_diag_table_mutex);
  		if (inet_rcv_compat != NULL)
  			ret = inet_rcv_compat(skb, nlh);
  		else
  			ret = -EOPNOTSUPP;
  		mutex_unlock(&sock_diag_table_mutex);
  
  		return ret;
  	case SOCK_DIAG_BY_FAMILY:
  		return __sock_diag_rcv_msg(skb, nlh);
  	default:
  		return -EINVAL;
  	}
  }
  
  static DEFINE_MUTEX(sock_diag_mutex);
  
  static void sock_diag_rcv(struct sk_buff *skb)
  {
  	mutex_lock(&sock_diag_mutex);
  	netlink_rcv_skb(skb, &sock_diag_rcv_msg);
  	mutex_unlock(&sock_diag_mutex);
  }
  
  static int sock_diag_bind(struct net *net, int group)
  {
  	switch (group) {
  	case SKNLGRP_INET_TCP_DESTROY:
  	case SKNLGRP_INET_UDP_DESTROY:
  		if (!sock_diag_handlers[AF_INET])
  			request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
  				       NETLINK_SOCK_DIAG, AF_INET);
  		break;
  	case SKNLGRP_INET6_TCP_DESTROY:
  	case SKNLGRP_INET6_UDP_DESTROY:
  		if (!sock_diag_handlers[AF_INET6])
  			request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
  				       NETLINK_SOCK_DIAG, AF_INET);
  		break;
  	}
  	return 0;
  }
  
  static int __net_init diag_net_init(struct net *net)
  {
  	struct netlink_kernel_cfg cfg = {
  		.groups	= SKNLGRP_MAX,
  		.input	= sock_diag_rcv,
  		.bind	= sock_diag_bind,
  		.flags	= NL_CFG_F_NONROOT_RECV,
  	};
  
  	net->diag_nlsk = netlink_kernel_create(net, NETLINK_SOCK_DIAG, &cfg);
  	return net->diag_nlsk == NULL ? -ENOMEM : 0;
  }
  
  static void __net_exit diag_net_exit(struct net *net)
  {
  	netlink_kernel_release(net->diag_nlsk);
  	net->diag_nlsk = NULL;
  }
  
  static struct pernet_operations diag_net_ops = {
  	.init = diag_net_init,
  	.exit = diag_net_exit,
  };
  
  static int __init sock_diag_init(void)
  {
  	broadcast_wq = alloc_workqueue("sock_diag_events", 0, 0);
  	BUG_ON(!broadcast_wq);
  	return register_pernet_subsys(&diag_net_ops);
  }
  device_initcall(sock_diag_init);