1// SPDX-License-Identifier: GPL-2.0
2/*
3 * kernel userspace event delivery
4 *
5 * Copyright (C) 2004 Red Hat, Inc.  All rights reserved.
6 * Copyright (C) 2004 Novell, Inc.  All rights reserved.
7 * Copyright (C) 2004 IBM, Inc. All rights reserved.
8 *
9 * Authors:
10 *	Robert Love		<rml@novell.com>
11 *	Kay Sievers		<kay.sievers@vrfy.org>
12 *	Arjan van de Ven	<arjanv@redhat.com>
13 *	Greg Kroah-Hartman	<greg@kroah.com>
14 */
15
16#include <linux/spinlock.h>
17#include <linux/string.h>
18#include <linux/kobject.h>
19#include <linux/export.h>
20#include <linux/kmod.h>
21#include <linux/slab.h>
22#include <linux/socket.h>
23#include <linux/skbuff.h>
24#include <linux/netlink.h>
25#include <linux/uidgid.h>
26#include <linux/uuid.h>
27#include <linux/ctype.h>
28#include <net/sock.h>
29#include <net/netlink.h>
30#include <net/net_namespace.h>
31
32
33u64 uevent_seqnum;
34#ifdef CONFIG_UEVENT_HELPER
35char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
36#endif
37
38struct uevent_sock {
39	struct list_head list;
40	struct sock *sk;
41};
42
43#ifdef CONFIG_NET
44static LIST_HEAD(uevent_sock_list);
45#endif
46
47/* This lock protects uevent_seqnum and uevent_sock_list */
48static DEFINE_MUTEX(uevent_sock_mutex);
49
50/* the strings here must match the enum in include/linux/kobject.h */
51static const char *kobject_actions[] = {
52	[KOBJ_ADD] =		"add",
53	[KOBJ_REMOVE] =		"remove",
54	[KOBJ_CHANGE] =		"change",
55	[KOBJ_MOVE] =		"move",
56	[KOBJ_ONLINE] =		"online",
57	[KOBJ_OFFLINE] =	"offline",
58	[KOBJ_BIND] =		"bind",
59	[KOBJ_UNBIND] =		"unbind",
60};
61
62static int kobject_action_type(const char *buf, size_t count,
63			       enum kobject_action *type,
64			       const char **args)
65{
66	enum kobject_action action;
67	size_t count_first;
68	const char *args_start;
69	int ret = -EINVAL;
70
71	if (count && (buf[count-1] == '\n' || buf[count-1] == '\0'))
72		count--;
73
74	if (!count)
75		goto out;
76
77	args_start = strnchr(buf, count, ' ');
78	if (args_start) {
79		count_first = args_start - buf;
80		args_start = args_start + 1;
81	} else
82		count_first = count;
83
84	for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
85		if (strncmp(kobject_actions[action], buf, count_first) != 0)
86			continue;
87		if (kobject_actions[action][count_first] != '\0')
88			continue;
89		if (args)
90			*args = args_start;
91		*type = action;
92		ret = 0;
93		break;
94	}
95out:
96	return ret;
97}
98
99static const char *action_arg_word_end(const char *buf, const char *buf_end,
100				       char delim)
101{
102	const char *next = buf;
103
104	while (next <= buf_end && *next != delim)
105		if (!isalnum(*next++))
106			return NULL;
107
108	if (next == buf)
109		return NULL;
110
111	return next;
112}
113
114static int kobject_action_args(const char *buf, size_t count,
115			       struct kobj_uevent_env **ret_env)
116{
117	struct kobj_uevent_env *env = NULL;
118	const char *next, *buf_end, *key;
119	int key_len;
120	int r = -EINVAL;
121
122	if (count && (buf[count - 1] == '\n' || buf[count - 1] == '\0'))
123		count--;
124
125	if (!count)
126		return -EINVAL;
127
128	env = kzalloc(sizeof(*env), GFP_KERNEL);
129	if (!env)
130		return -ENOMEM;
131
132	/* first arg is UUID */
133	if (count < UUID_STRING_LEN || !uuid_is_valid(buf) ||
134	    add_uevent_var(env, "SYNTH_UUID=%.*s", UUID_STRING_LEN, buf))
135		goto out;
136
137	/*
138	 * the rest are custom environment variables in KEY=VALUE
139	 * format with ' ' delimiter between each KEY=VALUE pair
140	 */
141	next = buf + UUID_STRING_LEN;
142	buf_end = buf + count - 1;
143
144	while (next <= buf_end) {
145		if (*next != ' ')
146			goto out;
147
148		/* skip the ' ', key must follow */
149		key = ++next;
150		if (key > buf_end)
151			goto out;
152
153		buf = next;
154		next = action_arg_word_end(buf, buf_end, '=');
155		if (!next || next > buf_end || *next != '=')
156			goto out;
157		key_len = next - buf;
158
159		/* skip the '=', value must follow */
160		if (++next > buf_end)
161			goto out;
162
163		buf = next;
164		next = action_arg_word_end(buf, buf_end, ' ');
165		if (!next)
166			goto out;
167
168		if (add_uevent_var(env, "SYNTH_ARG_%.*s=%.*s",
169				   key_len, key, (int) (next - buf), buf))
170			goto out;
171	}
172
173	r = 0;
174out:
175	if (r)
176		kfree(env);
177	else
178		*ret_env = env;
179	return r;
180}
181
182/**
183 * kobject_synth_uevent - send synthetic uevent with arguments
184 *
185 * @kobj: struct kobject for which synthetic uevent is to be generated
186 * @buf: buffer containing action type and action args, newline is ignored
187 * @count: length of buffer
188 *
189 * Returns 0 if kobject_synthetic_uevent() is completed with success or the
190 * corresponding error when it fails.
191 */
192int kobject_synth_uevent(struct kobject *kobj, const char *buf, size_t count)
193{
194	char *no_uuid_envp[] = { "SYNTH_UUID=0", NULL };
195	enum kobject_action action;
196	const char *action_args;
197	struct kobj_uevent_env *env;
198	const char *msg = NULL, *devpath;
199	int r;
200
201	r = kobject_action_type(buf, count, &action, &action_args);
202	if (r) {
203		msg = "unknown uevent action string";
204		goto out;
205	}
206
207	if (!action_args) {
208		r = kobject_uevent_env(kobj, action, no_uuid_envp);
209		goto out;
210	}
211
212	r = kobject_action_args(action_args,
213				count - (action_args - buf), &env);
214	if (r == -EINVAL) {
215		msg = "incorrect uevent action arguments";
216		goto out;
217	}
218
219	if (r)
220		goto out;
221
222	r = kobject_uevent_env(kobj, action, env->envp);
223	kfree(env);
224out:
225	if (r) {
226		devpath = kobject_get_path(kobj, GFP_KERNEL);
227		pr_warn("synth uevent: %s: %s\n",
228		       devpath ?: "unknown device",
229		       msg ?: "failed to send uevent");
230		kfree(devpath);
231	}
232	return r;
233}
234
235#ifdef CONFIG_UEVENT_HELPER
236static int kobj_usermode_filter(struct kobject *kobj)
237{
238	const struct kobj_ns_type_operations *ops;
239
240	ops = kobj_ns_ops(kobj);
241	if (ops) {
242		const void *init_ns, *ns;
243
244		ns = kobj->ktype->namespace(kobj);
245		init_ns = ops->initial_ns();
246		return ns != init_ns;
247	}
248
249	return 0;
250}
251
252static int init_uevent_argv(struct kobj_uevent_env *env, const char *subsystem)
253{
254	int buffer_size = sizeof(env->buf) - env->buflen;
255	int len;
256
257	len = strlcpy(&env->buf[env->buflen], subsystem, buffer_size);
258	if (len >= buffer_size) {
259		pr_warn("init_uevent_argv: buffer size of %d too small, needed %d\n",
260			buffer_size, len);
261		return -ENOMEM;
262	}
263
264	env->argv[0] = uevent_helper;
265	env->argv[1] = &env->buf[env->buflen];
266	env->argv[2] = NULL;
267
268	env->buflen += len + 1;
269	return 0;
270}
271
272static void cleanup_uevent_env(struct subprocess_info *info)
273{
274	kfree(info->data);
275}
276#endif
277
278#ifdef CONFIG_NET
279static struct sk_buff *alloc_uevent_skb(struct kobj_uevent_env *env,
280					const char *action_string,
281					const char *devpath)
282{
283	struct netlink_skb_parms *parms;
284	struct sk_buff *skb = NULL;
285	char *scratch;
286	size_t len;
287
288	/* allocate message with maximum possible size */
289	len = strlen(action_string) + strlen(devpath) + 2;
290	skb = alloc_skb(len + env->buflen, GFP_KERNEL);
291	if (!skb)
292		return NULL;
293
294	/* add header */
295	scratch = skb_put(skb, len);
296	sprintf(scratch, "%s@%s", action_string, devpath);
297
298	skb_put_data(skb, env->buf, env->buflen);
299
300	parms = &NETLINK_CB(skb);
301	parms->creds.uid = GLOBAL_ROOT_UID;
302	parms->creds.gid = GLOBAL_ROOT_GID;
303	parms->dst_group = 1;
304	parms->portid = 0;
305
306	return skb;
307}
308
309static int uevent_net_broadcast_untagged(struct kobj_uevent_env *env,
310					 const char *action_string,
311					 const char *devpath)
312{
313	struct sk_buff *skb = NULL;
314	struct uevent_sock *ue_sk;
315	int retval = 0;
316
317	/* send netlink message */
318	list_for_each_entry(ue_sk, &uevent_sock_list, list) {
319		struct sock *uevent_sock = ue_sk->sk;
320
321		if (!netlink_has_listeners(uevent_sock, 1))
322			continue;
323
324		if (!skb) {
325			retval = -ENOMEM;
326			skb = alloc_uevent_skb(env, action_string, devpath);
327			if (!skb)
328				continue;
329		}
330
331		retval = netlink_broadcast(uevent_sock, skb_get(skb), 0, 1,
332					   GFP_KERNEL);
333		/* ENOBUFS should be handled in userspace */
334		if (retval == -ENOBUFS || retval == -ESRCH)
335			retval = 0;
336	}
337	consume_skb(skb);
338
339	return retval;
340}
341
342static int uevent_net_broadcast_tagged(struct sock *usk,
343				       struct kobj_uevent_env *env,
344				       const char *action_string,
345				       const char *devpath)
346{
347	struct user_namespace *owning_user_ns = sock_net(usk)->user_ns;
348	struct sk_buff *skb = NULL;
349	int ret = 0;
350
351	skb = alloc_uevent_skb(env, action_string, devpath);
352	if (!skb)
353		return -ENOMEM;
354
355	/* fix credentials */
356	if (owning_user_ns != &init_user_ns) {
357		struct netlink_skb_parms *parms = &NETLINK_CB(skb);
358		kuid_t root_uid;
359		kgid_t root_gid;
360
361		/* fix uid */
362		root_uid = make_kuid(owning_user_ns, 0);
363		if (uid_valid(root_uid))
364			parms->creds.uid = root_uid;
365
366		/* fix gid */
367		root_gid = make_kgid(owning_user_ns, 0);
368		if (gid_valid(root_gid))
369			parms->creds.gid = root_gid;
370	}
371
372	ret = netlink_broadcast(usk, skb, 0, 1, GFP_KERNEL);
373	/* ENOBUFS should be handled in userspace */
374	if (ret == -ENOBUFS || ret == -ESRCH)
375		ret = 0;
376
377	return ret;
378}
379#endif
380
381static int kobject_uevent_net_broadcast(struct kobject *kobj,
382					struct kobj_uevent_env *env,
383					const char *action_string,
384					const char *devpath)
385{
386	int ret = 0;
387
388#ifdef CONFIG_NET
389	const struct kobj_ns_type_operations *ops;
390	const struct net *net = NULL;
391
392	ops = kobj_ns_ops(kobj);
393	if (!ops && kobj->kset) {
394		struct kobject *ksobj = &kobj->kset->kobj;
395
396		if (ksobj->parent != NULL)
397			ops = kobj_ns_ops(ksobj->parent);
398	}
399
400	/* kobjects currently only carry network namespace tags and they
401	 * are the only tag relevant here since we want to decide which
402	 * network namespaces to broadcast the uevent into.
403	 */
404	if (ops && ops->netlink_ns && kobj->ktype->namespace)
405		if (ops->type == KOBJ_NS_TYPE_NET)
406			net = kobj->ktype->namespace(kobj);
407
408	if (!net)
409		ret = uevent_net_broadcast_untagged(env, action_string,
410						    devpath);
411	else
412		ret = uevent_net_broadcast_tagged(net->uevent_sock->sk, env,
413						  action_string, devpath);
414#endif
415
416	return ret;
417}
418
419static void zap_modalias_env(struct kobj_uevent_env *env)
420{
421	static const char modalias_prefix[] = "MODALIAS=";
422	size_t len;
423	int i, j;
424
425	for (i = 0; i < env->envp_idx;) {
426		if (strncmp(env->envp[i], modalias_prefix,
427			    sizeof(modalias_prefix) - 1)) {
428			i++;
429			continue;
430		}
431
432		len = strlen(env->envp[i]) + 1;
433
434		if (i != env->envp_idx - 1) {
435			/* @env->envp[] contains pointers to @env->buf[]
436			 * with @env->buflen chars, and we are removing
437			 * variable MODALIAS here pointed by @env->envp[i]
438			 * with length @len as shown below:
439			 *
440			 * 0               @env->buf[]      @env->buflen
441			 * ---------------------------------------------
442			 * ^             ^              ^              ^
443			 * |             |->   @len   <-| target block |
444			 * @env->envp[0] @env->envp[i]  @env->envp[i + 1]
445			 *
446			 * so the "target block" indicated above is moved
447			 * backward by @len, and its right size is
448			 * @env->buflen - (@env->envp[i + 1] - @env->envp[0]).
449			 */
450			memmove(env->envp[i], env->envp[i + 1],
451				env->buflen - (env->envp[i + 1] - env->envp[0]));
452
453			for (j = i; j < env->envp_idx - 1; j++)
454				env->envp[j] = env->envp[j + 1] - len;
455		}
456
457		env->envp_idx--;
458		env->buflen -= len;
459	}
460}
461
462/**
463 * kobject_uevent_env - send an uevent with environmental data
464 *
465 * @kobj: struct kobject that the action is happening to
466 * @action: action that is happening
467 * @envp_ext: pointer to environmental data
468 *
469 * Returns 0 if kobject_uevent_env() is completed with success or the
470 * corresponding error when it fails.
471 */
472int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
473		       char *envp_ext[])
474{
475	struct kobj_uevent_env *env;
476	const char *action_string = kobject_actions[action];
477	const char *devpath = NULL;
478	const char *subsystem;
479	struct kobject *top_kobj;
480	struct kset *kset;
481	const struct kset_uevent_ops *uevent_ops;
482	int i = 0;
483	int retval = 0;
484
485	/*
486	 * Mark "remove" event done regardless of result, for some subsystems
487	 * do not want to re-trigger "remove" event via automatic cleanup.
488	 */
489	if (action == KOBJ_REMOVE)
490		kobj->state_remove_uevent_sent = 1;
491
492	pr_debug("kobject: '%s' (%p): %s\n",
493		 kobject_name(kobj), kobj, __func__);
494
495	/* search the kset we belong to */
496	top_kobj = kobj;
497	while (!top_kobj->kset && top_kobj->parent)
498		top_kobj = top_kobj->parent;
499
500	if (!top_kobj->kset) {
501		pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
502			 "without kset!\n", kobject_name(kobj), kobj,
503			 __func__);
504		return -EINVAL;
505	}
506
507	kset = top_kobj->kset;
508	uevent_ops = kset->uevent_ops;
509
510	/* skip the event, if uevent_suppress is set*/
511	if (kobj->uevent_suppress) {
512		pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
513				 "caused the event to drop!\n",
514				 kobject_name(kobj), kobj, __func__);
515		return 0;
516	}
517	/* skip the event, if the filter returns zero. */
518	if (uevent_ops && uevent_ops->filter)
519		if (!uevent_ops->filter(kset, kobj)) {
520			pr_debug("kobject: '%s' (%p): %s: filter function "
521				 "caused the event to drop!\n",
522				 kobject_name(kobj), kobj, __func__);
523			return 0;
524		}
525
526	/* originating subsystem */
527	if (uevent_ops && uevent_ops->name)
528		subsystem = uevent_ops->name(kset, kobj);
529	else
530		subsystem = kobject_name(&kset->kobj);
531	if (!subsystem) {
532		pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
533			 "event to drop!\n", kobject_name(kobj), kobj,
534			 __func__);
535		return 0;
536	}
537
538	/* environment buffer */
539	env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
540	if (!env)
541		return -ENOMEM;
542
543	/* complete object path */
544	devpath = kobject_get_path(kobj, GFP_KERNEL);
545	if (!devpath) {
546		retval = -ENOENT;
547		goto exit;
548	}
549
550	/* default keys */
551	retval = add_uevent_var(env, "ACTION=%s", action_string);
552	if (retval)
553		goto exit;
554	retval = add_uevent_var(env, "DEVPATH=%s", devpath);
555	if (retval)
556		goto exit;
557	retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
558	if (retval)
559		goto exit;
560
561	/* keys passed in from the caller */
562	if (envp_ext) {
563		for (i = 0; envp_ext[i]; i++) {
564			retval = add_uevent_var(env, "%s", envp_ext[i]);
565			if (retval)
566				goto exit;
567		}
568	}
569
570	/* let the kset specific function add its stuff */
571	if (uevent_ops && uevent_ops->uevent) {
572		retval = uevent_ops->uevent(kset, kobj, env);
573		if (retval) {
574			pr_debug("kobject: '%s' (%p): %s: uevent() returned "
575				 "%d\n", kobject_name(kobj), kobj,
576				 __func__, retval);
577			goto exit;
578		}
579	}
580
581	switch (action) {
582	case KOBJ_ADD:
583		/*
584		 * Mark "add" event so we can make sure we deliver "remove"
585		 * event to userspace during automatic cleanup. If
586		 * the object did send an "add" event, "remove" will
587		 * automatically generated by the core, if not already done
588		 * by the caller.
589		 */
590		kobj->state_add_uevent_sent = 1;
591		break;
592
593	case KOBJ_UNBIND:
594		zap_modalias_env(env);
595		break;
596
597	default:
598		break;
599	}
600
601	mutex_lock(&uevent_sock_mutex);
602	/* we will send an event, so request a new sequence number */
603	retval = add_uevent_var(env, "SEQNUM=%llu", ++uevent_seqnum);
604	if (retval) {
605		mutex_unlock(&uevent_sock_mutex);
606		goto exit;
607	}
608	retval = kobject_uevent_net_broadcast(kobj, env, action_string,
609					      devpath);
610	mutex_unlock(&uevent_sock_mutex);
611
612#ifdef CONFIG_UEVENT_HELPER
613	/* call uevent_helper, usually only enabled during early boot */
614	if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
615		struct subprocess_info *info;
616
617		retval = add_uevent_var(env, "HOME=/");
618		if (retval)
619			goto exit;
620		retval = add_uevent_var(env,
621					"PATH=/sbin:/bin:/usr/sbin:/usr/bin");
622		if (retval)
623			goto exit;
624		retval = init_uevent_argv(env, subsystem);
625		if (retval)
626			goto exit;
627
628		retval = -ENOMEM;
629		info = call_usermodehelper_setup(env->argv[0], env->argv,
630						 env->envp, GFP_KERNEL,
631						 NULL, cleanup_uevent_env, env);
632		if (info) {
633			retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
634			env = NULL;	/* freed by cleanup_uevent_env */
635		}
636	}
637#endif
638
639exit:
640	kfree(devpath);
641	kfree(env);
642	return retval;
643}
644EXPORT_SYMBOL_GPL(kobject_uevent_env);
645
646/**
647 * kobject_uevent - notify userspace by sending an uevent
648 *
649 * @kobj: struct kobject that the action is happening to
650 * @action: action that is happening
651 *
652 * Returns 0 if kobject_uevent() is completed with success or the
653 * corresponding error when it fails.
654 */
655int kobject_uevent(struct kobject *kobj, enum kobject_action action)
656{
657	return kobject_uevent_env(kobj, action, NULL);
658}
659EXPORT_SYMBOL_GPL(kobject_uevent);
660
661/**
662 * add_uevent_var - add key value string to the environment buffer
663 * @env: environment buffer structure
664 * @format: printf format for the key=value pair
665 *
666 * Returns 0 if environment variable was added successfully or -ENOMEM
667 * if no space was available.
668 */
669int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
670{
671	va_list args;
672	int len;
673
674	if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
675		WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
676		return -ENOMEM;
677	}
678
679	va_start(args, format);
680	len = vsnprintf(&env->buf[env->buflen],
681			sizeof(env->buf) - env->buflen,
682			format, args);
683	va_end(args);
684
685	if (len >= (sizeof(env->buf) - env->buflen)) {
686		WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
687		return -ENOMEM;
688	}
689
690	env->envp[env->envp_idx++] = &env->buf[env->buflen];
691	env->buflen += len + 1;
692	return 0;
693}
694EXPORT_SYMBOL_GPL(add_uevent_var);
695
696#if defined(CONFIG_NET)
697static int uevent_net_broadcast(struct sock *usk, struct sk_buff *skb,
698				struct netlink_ext_ack *extack)
699{
700	/* u64 to chars: 2^64 - 1 = 21 chars */
701	char buf[sizeof("SEQNUM=") + 21];
702	struct sk_buff *skbc;
703	int ret;
704
705	/* bump and prepare sequence number */
706	ret = snprintf(buf, sizeof(buf), "SEQNUM=%llu", ++uevent_seqnum);
707	if (ret < 0 || (size_t)ret >= sizeof(buf))
708		return -ENOMEM;
709	ret++;
710
711	/* verify message does not overflow */
712	if ((skb->len + ret) > UEVENT_BUFFER_SIZE) {
713		NL_SET_ERR_MSG(extack, "uevent message too big");
714		return -EINVAL;
715	}
716
717	/* copy skb and extend to accommodate sequence number */
718	skbc = skb_copy_expand(skb, 0, ret, GFP_KERNEL);
719	if (!skbc)
720		return -ENOMEM;
721
722	/* append sequence number */
723	skb_put_data(skbc, buf, ret);
724
725	/* remove msg header */
726	skb_pull(skbc, NLMSG_HDRLEN);
727
728	/* set portid 0 to inform userspace message comes from kernel */
729	NETLINK_CB(skbc).portid = 0;
730	NETLINK_CB(skbc).dst_group = 1;
731
732	ret = netlink_broadcast(usk, skbc, 0, 1, GFP_KERNEL);
733	/* ENOBUFS should be handled in userspace */
734	if (ret == -ENOBUFS || ret == -ESRCH)
735		ret = 0;
736
737	return ret;
738}
739
740static int uevent_net_rcv_skb(struct sk_buff *skb, struct nlmsghdr *nlh,
741			      struct netlink_ext_ack *extack)
742{
743	struct net *net;
744	int ret;
745
746	if (!nlmsg_data(nlh))
747		return -EINVAL;
748
749	/*
750	 * Verify that we are allowed to send messages to the target
751	 * network namespace. The caller must have CAP_SYS_ADMIN in the
752	 * owning user namespace of the target network namespace.
753	 */
754	net = sock_net(NETLINK_CB(skb).sk);
755	if (!netlink_ns_capable(skb, net->user_ns, CAP_SYS_ADMIN)) {
756		NL_SET_ERR_MSG(extack, "missing CAP_SYS_ADMIN capability");
757		return -EPERM;
758	}
759
760	mutex_lock(&uevent_sock_mutex);
761	ret = uevent_net_broadcast(net->uevent_sock->sk, skb, extack);
762	mutex_unlock(&uevent_sock_mutex);
763
764	return ret;
765}
766
767static void uevent_net_rcv(struct sk_buff *skb)
768{
769	netlink_rcv_skb(skb, &uevent_net_rcv_skb);
770}
771
772static int uevent_net_init(struct net *net)
773{
774	struct uevent_sock *ue_sk;
775	struct netlink_kernel_cfg cfg = {
776		.groups	= 1,
777		.input = uevent_net_rcv,
778		.flags	= NL_CFG_F_NONROOT_RECV
779	};
780
781	ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
782	if (!ue_sk)
783		return -ENOMEM;
784
785	ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
786	if (!ue_sk->sk) {
787		pr_err("kobject_uevent: unable to create netlink socket!\n");
788		kfree(ue_sk);
789		return -ENODEV;
790	}
791
792	net->uevent_sock = ue_sk;
793
794	/* Restrict uevents to initial user namespace. */
795	if (sock_net(ue_sk->sk)->user_ns == &init_user_ns) {
796		mutex_lock(&uevent_sock_mutex);
797		list_add_tail(&ue_sk->list, &uevent_sock_list);
798		mutex_unlock(&uevent_sock_mutex);
799	}
800
801	return 0;
802}
803
804static void uevent_net_exit(struct net *net)
805{
806	struct uevent_sock *ue_sk = net->uevent_sock;
807
808	if (sock_net(ue_sk->sk)->user_ns == &init_user_ns) {
809		mutex_lock(&uevent_sock_mutex);
810		list_del(&ue_sk->list);
811		mutex_unlock(&uevent_sock_mutex);
812	}
813
814	netlink_kernel_release(ue_sk->sk);
815	kfree(ue_sk);
816}
817
818static struct pernet_operations uevent_net_ops = {
819	.init	= uevent_net_init,
820	.exit	= uevent_net_exit,
821};
822
823static int __init kobject_uevent_init(void)
824{
825	return register_pernet_subsys(&uevent_net_ops);
826}
827
828
829postcore_initcall(kobject_uevent_init);
830#endif
831