/*
   * kernel userspace event delivery
   *
   * Copyright (C) 2004 Red Hat, Inc.  All rights reserved.
   * Copyright (C) 2004 Novell, Inc.  All rights reserved.
   * Copyright (C) 2004 IBM, Inc. All rights reserved.
   *
   * Licensed under the GNU GPL v2.
   *
   * Authors:
   *	Robert Love		<rml@novell.com>
   *	Kay Sievers		<kay.sievers@vrfy.org>
   *	Arjan van de Ven	<arjanv@redhat.com>
   *	Greg Kroah-Hartman	<greg@kroah.com>
   */
  
  #include <linux/spinlock.h>

  #include <linux/string.h>
  #include <linux/kobject.h>
  #include <linux/module.h>

  #include <linux/slab.h>

  #include <linux/user_namespace.h>

  #include <linux/socket.h>
  #include <linux/skbuff.h>
  #include <linux/netlink.h>

  #include <net/sock.h>

  #include <net/net_namespace.h>

  u64 uevent_seqnum;

  char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;

  static DEFINE_SPINLOCK(sequence_lock);

  #ifdef CONFIG_NET
  struct uevent_sock {
  	struct list_head list;
  	struct sock *sk;
  };
  static LIST_HEAD(uevent_sock_list);
  static DEFINE_MUTEX(uevent_sock_mutex);

  #endif

  /* the strings here must match the enum in include/linux/kobject.h */
  static const char *kobject_actions[] = {
  	[KOBJ_ADD] =		"add",
  	[KOBJ_REMOVE] =		"remove",
  	[KOBJ_CHANGE] =		"change",
  	[KOBJ_MOVE] =		"move",
  	[KOBJ_ONLINE] =		"online",
  	[KOBJ_OFFLINE] =	"offline",
  };
  
  /**
   * kobject_action_type - translate action string to numeric type
   *
   * @buf: buffer containing the action string, newline is ignored
   * @len: length of buffer
   * @type: pointer to the location to store the action type
   *
   * Returns 0 if the action string was recognized.
   */
  int kobject_action_type(const char *buf, size_t count,
  			enum kobject_action *type)
  {
  	enum kobject_action action;
  	int ret = -EINVAL;

  	if (count && (buf[count-1] == '
  ' || buf[count-1] == '\0'))

  		count--;
  
  	if (!count)
  		goto out;
  
  	for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
  		if (strncmp(kobject_actions[action], buf, count) != 0)
  			continue;
  		if (kobject_actions[action][count] != '\0')
  			continue;
  		*type = action;
  		ret = 0;
  		break;
  	}
  out:
  	return ret;
  }

  #ifdef CONFIG_NET

  static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data)
  {
  	struct kobject *kobj = data;
  	const struct kobj_ns_type_operations *ops;
  
  	ops = kobj_ns_ops(kobj);
  	if (ops) {
  		const void *sock_ns, *ns;
  		ns = kobj->ktype->namespace(kobj);
  		sock_ns = ops->netlink_ns(dsk);
  		return sock_ns != ns;
  	}
  
  	return 0;
  }

  #endif

  static int kobj_usermode_filter(struct kobject *kobj)
  {
  	const struct kobj_ns_type_operations *ops;
  
  	ops = kobj_ns_ops(kobj);
  	if (ops) {
  		const void *init_ns, *ns;
  		ns = kobj->ktype->namespace(kobj);
  		init_ns = ops->initial_ns();
  		return ns != init_ns;
  	}
  
  	return 0;
  }

  /**

   * kobject_uevent_env - send an uevent with environmental data

   *

   * @action: action that is happening

   * @kobj: struct kobject that the action is happening to

   * @envp_ext: pointer to environmental data

   *

   * Returns 0 if kobject_uevent_env() is completed with success or the

   * corresponding error when it fails.

   */

  int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,

  		       char *envp_ext[])

  {

  	struct kobj_uevent_env *env;
  	const char *action_string = kobject_actions[action];

  	const char *devpath = NULL;
  	const char *subsystem;
  	struct kobject *top_kobj;
  	struct kset *kset;

  	const struct kset_uevent_ops *uevent_ops;

  	u64 seq;

  	int i = 0;

  	int retval = 0;

  #ifdef CONFIG_NET
  	struct uevent_sock *ue_sk;
  #endif

  	pr_debug("kobject: '%s' (%p): %s
  ",

  		 kobject_name(kobj), kobj, __func__);

  	/* search the kset we belong to */
  	top_kobj = kobj;

  	while (!top_kobj->kset && top_kobj->parent)

  		top_kobj = top_kobj->parent;

  	if (!top_kobj->kset) {

  		pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
  			 "without kset!
  ", kobject_name(kobj), kobj,

  			 __func__);

  		return -EINVAL;
  	}

  	kset = top_kobj->kset;

  	uevent_ops = kset->uevent_ops;

  	/* skip the event, if uevent_suppress is set*/
  	if (kobj->uevent_suppress) {
  		pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
  				 "caused the event to drop!
  ",
  				 kobject_name(kobj), kobj, __func__);
  		return 0;
  	}

  	/* skip the event, if the filter returns zero. */

  	if (uevent_ops && uevent_ops->filter)

  		if (!uevent_ops->filter(kset, kobj)) {

  			pr_debug("kobject: '%s' (%p): %s: filter function "
  				 "caused the event to drop!
  ",

  				 kobject_name(kobj), kobj, __func__);

  			return 0;
  		}

  	/* originating subsystem */
  	if (uevent_ops && uevent_ops->name)
  		subsystem = uevent_ops->name(kset, kobj);
  	else
  		subsystem = kobject_name(&kset->kobj);
  	if (!subsystem) {

  		pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
  			 "event to drop!
  ", kobject_name(kobj), kobj,

  			 __func__);

  		return 0;
  	}

  	/* environment buffer */
  	env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
  	if (!env)

  		return -ENOMEM;

  	/* complete object path */
  	devpath = kobject_get_path(kobj, GFP_KERNEL);

  	if (!devpath) {
  		retval = -ENOENT;

  		goto exit;

  	}

  	/* default keys */

  	retval = add_uevent_var(env, "ACTION=%s", action_string);
  	if (retval)
  		goto exit;
  	retval = add_uevent_var(env, "DEVPATH=%s", devpath);
  	if (retval)
  		goto exit;
  	retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
  	if (retval)
  		goto exit;
  
  	/* keys passed in from the caller */
  	if (envp_ext) {
  		for (i = 0; envp_ext[i]; i++) {

  			retval = add_uevent_var(env, "%s", envp_ext[i]);

  			if (retval)
  				goto exit;
  		}
  	}

  	/* let the kset specific function add its stuff */

  	if (uevent_ops && uevent_ops->uevent) {

  		retval = uevent_ops->uevent(kset, kobj, env);

  		if (retval) {

  			pr_debug("kobject: '%s' (%p): %s: uevent() returned "
  				 "%d
  ", kobject_name(kobj), kobj,

  				 __func__, retval);

  			goto exit;
  		}
  	}

  	/*
  	 * Mark "add" and "remove" events in the object to ensure proper
  	 * events to userspace during automatic cleanup. If the object did
  	 * send an "add" event, "remove" will automatically generated by
  	 * the core, if not already done by the caller.
  	 */
  	if (action == KOBJ_ADD)
  		kobj->state_add_uevent_sent = 1;
  	else if (action == KOBJ_REMOVE)
  		kobj->state_remove_uevent_sent = 1;

  	/* we will send an event, so request a new sequence number */

  	spin_lock(&sequence_lock);

  	seq = ++uevent_seqnum;

  	spin_unlock(&sequence_lock);

  	retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)seq);
  	if (retval)
  		goto exit;

  #if defined(CONFIG_NET)

  	/* send netlink message */

  	mutex_lock(&uevent_sock_mutex);
  	list_for_each_entry(ue_sk, &uevent_sock_list, list) {
  		struct sock *uevent_sock = ue_sk->sk;

  		struct sk_buff *skb;
  		size_t len;
  
  		/* allocate message with the maximum possible size */
  		len = strlen(action_string) + strlen(devpath) + 2;

  		skb = alloc_skb(len + env->buflen, GFP_KERNEL);

  		if (skb) {

  			char *scratch;

  			/* add header */
  			scratch = skb_put(skb, len);
  			sprintf(scratch, "%s@%s", action_string, devpath);
  
  			/* copy keys to our continuous event payload buffer */

  			for (i = 0; i < env->envp_idx; i++) {
  				len = strlen(env->envp[i]) + 1;

  				scratch = skb_put(skb, len);

  				strcpy(scratch, env->envp[i]);

  			}
  
  			NETLINK_CB(skb).dst_group = 1;

  			retval = netlink_broadcast_filtered(uevent_sock, skb,
  							    0, 1, GFP_KERNEL,
  							    kobj_bcast_filter,
  							    kobj);

  			/* ENOBUFS should be handled in userspace */
  			if (retval == -ENOBUFS)
  				retval = 0;

  		} else
  			retval = -ENOMEM;

  	}

  	mutex_unlock(&uevent_sock_mutex);

  #endif

  	/* call uevent_helper, usually only enabled during early boot */

  	if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {

  		char *argv [3];

  		argv [0] = uevent_helper;

  		argv [1] = (char *)subsystem;
  		argv [2] = NULL;

  		retval = add_uevent_var(env, "HOME=/");
  		if (retval)
  			goto exit;

  		retval = add_uevent_var(env,
  					"PATH=/sbin:/bin:/usr/sbin:/usr/bin");

  		if (retval)
  			goto exit;

  		retval = call_usermodehelper(argv[0], argv,

  					     env->envp, UMH_WAIT_EXEC);

  	}

  
  exit:

  	kfree(devpath);

  	kfree(env);

  	return retval;

  }

  EXPORT_SYMBOL_GPL(kobject_uevent_env);
  
  /**

   * kobject_uevent - notify userspace by sending an uevent

   *

   * @action: action that is happening

   * @kobj: struct kobject that the action is happening to

   *
   * Returns 0 if kobject_uevent() is completed with success or the
   * corresponding error when it fails.

   */

  int kobject_uevent(struct kobject *kobj, enum kobject_action action)

  {

  	return kobject_uevent_env(kobj, action, NULL);

  }

  EXPORT_SYMBOL_GPL(kobject_uevent);

  
  /**

   * add_uevent_var - add key value string to the environment buffer
   * @env: environment buffer structure
   * @format: printf format for the key=value pair

   *
   * Returns 0 if environment variable was added successfully or -ENOMEM
   * if no space was available.
   */

  int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)

  {
  	va_list args;

  	int len;

  	if (env->envp_idx >= ARRAY_SIZE(env->envp)) {

  		WARN(1, KERN_ERR "add_uevent_var: too many keys
  ");

  		return -ENOMEM;

  	}

  
  	va_start(args, format);

  	len = vsnprintf(&env->buf[env->buflen],
  			sizeof(env->buf) - env->buflen,
  			format, args);

  	va_end(args);

  	if (len >= (sizeof(env->buf) - env->buflen)) {

  		WARN(1, KERN_ERR "add_uevent_var: buffer size too small
  ");

  		return -ENOMEM;

  	}

  	env->envp[env->envp_idx++] = &env->buf[env->buflen];
  	env->buflen += len + 1;

  	return 0;
  }

  EXPORT_SYMBOL_GPL(add_uevent_var);

  #if defined(CONFIG_NET)

  static int uevent_net_init(struct net *net)

  {

  	struct uevent_sock *ue_sk;
  
  	ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
  	if (!ue_sk)
  		return -ENOMEM;
  
  	ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT,
  					  1, NULL, NULL, THIS_MODULE);
  	if (!ue_sk->sk) {

  		printk(KERN_ERR
  		       "kobject_uevent: unable to create netlink socket!
  ");

  		kfree(ue_sk);

  		return -ENODEV;
  	}

  	mutex_lock(&uevent_sock_mutex);
  	list_add_tail(&ue_sk->list, &uevent_sock_list);
  	mutex_unlock(&uevent_sock_mutex);

  	return 0;
  }

  static void uevent_net_exit(struct net *net)
  {
  	struct uevent_sock *ue_sk;
  
  	mutex_lock(&uevent_sock_mutex);
  	list_for_each_entry(ue_sk, &uevent_sock_list, list) {
  		if (sock_net(ue_sk->sk) == net)
  			goto found;
  	}
  	mutex_unlock(&uevent_sock_mutex);
  	return;
  
  found:
  	list_del(&ue_sk->list);
  	mutex_unlock(&uevent_sock_mutex);
  
  	netlink_kernel_release(ue_sk->sk);
  	kfree(ue_sk);
  }
  
  static struct pernet_operations uevent_net_ops = {
  	.init	= uevent_net_init,
  	.exit	= uevent_net_exit,
  };
  
  static int __init kobject_uevent_init(void)
  {
  	netlink_set_nonroot(NETLINK_KOBJECT_UEVENT, NL_NONROOT_RECV);
  	return register_pernet_subsys(&uevent_net_ops);
  }

  postcore_initcall(kobject_uevent_init);

  #endif