xref: /openbmc/linux/lib/kobject_uevent.c (revision 4cff79e9) 
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/uuid.h>
26 #include <linux/ctype.h>
27 #include <net/sock.h>
28 #include <net/netlink.h>
29 #include <net/net_namespace.h>
30 
31 
32 u64 uevent_seqnum;
33 #ifdef CONFIG_UEVENT_HELPER
34 char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
35 #endif
36 
37 struct uevent_sock {
38 	struct list_head list;
39 	struct sock *sk;
40 };
41 
42 #ifdef CONFIG_NET
43 static LIST_HEAD(uevent_sock_list);
44 #endif
45 
46 /* This lock protects uevent_seqnum and uevent_sock_list */
47 static DEFINE_MUTEX(uevent_sock_mutex);
48 
49 /* the strings here must match the enum in include/linux/kobject.h */
50 static const char *kobject_actions[] = {
51 	[KOBJ_ADD] =		"add",
52 	[KOBJ_REMOVE] =		"remove",
53 	[KOBJ_CHANGE] =		"change",
54 	[KOBJ_MOVE] =		"move",
55 	[KOBJ_ONLINE] =		"online",
56 	[KOBJ_OFFLINE] =	"offline",
57 	[KOBJ_BIND] =		"bind",
58 	[KOBJ_UNBIND] =		"unbind",
59 };
60 
61 static int kobject_action_type(const char *buf, size_t count,
62 			       enum kobject_action *type,
63 			       const char **args)
64 {
65 	enum kobject_action action;
66 	size_t count_first;
67 	const char *args_start;
68 	int ret = -EINVAL;
69 
70 	if (count && (buf[count-1] == '\n' || buf[count-1] == '\0'))
71 		count--;
72 
73 	if (!count)
74 		goto out;
75 
76 	args_start = strnchr(buf, count, ' ');
77 	if (args_start) {
78 		count_first = args_start - buf;
79 		args_start = args_start + 1;
80 	} else
81 		count_first = count;
82 
83 	for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
84 		if (strncmp(kobject_actions[action], buf, count_first) != 0)
85 			continue;
86 		if (kobject_actions[action][count_first] != '\0')
87 			continue;
88 		if (args)
89 			*args = args_start;
90 		*type = action;
91 		ret = 0;
92 		break;
93 	}
94 out:
95 	return ret;
96 }
97 
98 static const char *action_arg_word_end(const char *buf, const char *buf_end,
99 				       char delim)
100 {
101 	const char *next = buf;
102 
103 	while (next <= buf_end && *next != delim)
104 		if (!isalnum(*next++))
105 			return NULL;
106 
107 	if (next == buf)
108 		return NULL;
109 
110 	return next;
111 }
112 
113 static int kobject_action_args(const char *buf, size_t count,
114 			       struct kobj_uevent_env **ret_env)
115 {
116 	struct kobj_uevent_env *env = NULL;
117 	const char *next, *buf_end, *key;
118 	int key_len;
119 	int r = -EINVAL;
120 
121 	if (count && (buf[count - 1] == '\n' || buf[count - 1] == '\0'))
122 		count--;
123 
124 	if (!count)
125 		return -EINVAL;
126 
127 	env = kzalloc(sizeof(*env), GFP_KERNEL);
128 	if (!env)
129 		return -ENOMEM;
130 
131 	/* first arg is UUID */
132 	if (count < UUID_STRING_LEN || !uuid_is_valid(buf) ||
133 	    add_uevent_var(env, "SYNTH_UUID=%.*s", UUID_STRING_LEN, buf))
134 		goto out;
135 
136 	/*
137 	 * the rest are custom environment variables in KEY=VALUE
138 	 * format with ' ' delimiter between each KEY=VALUE pair
139 	 */
140 	next = buf + UUID_STRING_LEN;
141 	buf_end = buf + count - 1;
142 
143 	while (next <= buf_end) {
144 		if (*next != ' ')
145 			goto out;
146 
147 		/* skip the ' ', key must follow */
148 		key = ++next;
149 		if (key > buf_end)
150 			goto out;
151 
152 		buf = next;
153 		next = action_arg_word_end(buf, buf_end, '=');
154 		if (!next || next > buf_end || *next != '=')
155 			goto out;
156 		key_len = next - buf;
157 
158 		/* skip the '=', value must follow */
159 		if (++next > buf_end)
160 			goto out;
161 
162 		buf = next;
163 		next = action_arg_word_end(buf, buf_end, ' ');
164 		if (!next)
165 			goto out;
166 
167 		if (add_uevent_var(env, "SYNTH_ARG_%.*s=%.*s",
168 				   key_len, key, (int) (next - buf), buf))
169 			goto out;
170 	}
171 
172 	r = 0;
173 out:
174 	if (r)
175 		kfree(env);
176 	else
177 		*ret_env = env;
178 	return r;
179 }
180 
181 /**
182  * kobject_synth_uevent - send synthetic uevent with arguments
183  *
184  * @kobj: struct kobject for which synthetic uevent is to be generated
185  * @buf: buffer containing action type and action args, newline is ignored
186  * @count: length of buffer
187  *
188  * Returns 0 if kobject_synthetic_uevent() is completed with success or the
189  * corresponding error when it fails.
190  */
191 int kobject_synth_uevent(struct kobject *kobj, const char *buf, size_t count)
192 {
193 	char *no_uuid_envp[] = { "SYNTH_UUID=0", NULL };
194 	enum kobject_action action;
195 	const char *action_args;
196 	struct kobj_uevent_env *env;
197 	const char *msg = NULL, *devpath;
198 	int r;
199 
200 	r = kobject_action_type(buf, count, &action, &action_args);
201 	if (r) {
202 		msg = "unknown uevent action string\n";
203 		goto out;
204 	}
205 
206 	if (!action_args) {
207 		r = kobject_uevent_env(kobj, action, no_uuid_envp);
208 		goto out;
209 	}
210 
211 	r = kobject_action_args(action_args,
212 				count - (action_args - buf), &env);
213 	if (r == -EINVAL) {
214 		msg = "incorrect uevent action arguments\n";
215 		goto out;
216 	}
217 
218 	if (r)
219 		goto out;
220 
221 	r = kobject_uevent_env(kobj, action, env->envp);
222 	kfree(env);
223 out:
224 	if (r) {
225 		devpath = kobject_get_path(kobj, GFP_KERNEL);
226 		printk(KERN_WARNING "synth uevent: %s: %s",
227 		       devpath ?: "unknown device",
228 		       msg ?: "failed to send uevent");
229 		kfree(devpath);
230 	}
231 	return r;
232 }
233 
234 #ifdef CONFIG_NET
235 static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data)
236 {
237 	struct kobject *kobj = data, *ksobj;
238 	const struct kobj_ns_type_operations *ops;
239 
240 	ops = kobj_ns_ops(kobj);
241 	if (!ops && kobj->kset) {
242 		ksobj = &kobj->kset->kobj;
243 		if (ksobj->parent != NULL)
244 			ops = kobj_ns_ops(ksobj->parent);
245 	}
246 
247 	if (ops && ops->netlink_ns && kobj->ktype->namespace) {
248 		const void *sock_ns, *ns;
249 		ns = kobj->ktype->namespace(kobj);
250 		sock_ns = ops->netlink_ns(dsk);
251 		return sock_ns != ns;
252 	}
253 
254 	return 0;
255 }
256 #endif
257 
258 #ifdef CONFIG_UEVENT_HELPER
259 static int kobj_usermode_filter(struct kobject *kobj)
260 {
261 	const struct kobj_ns_type_operations *ops;
262 
263 	ops = kobj_ns_ops(kobj);
264 	if (ops) {
265 		const void *init_ns, *ns;
266 		ns = kobj->ktype->namespace(kobj);
267 		init_ns = ops->initial_ns();
268 		return ns != init_ns;
269 	}
270 
271 	return 0;
272 }
273 
274 static int init_uevent_argv(struct kobj_uevent_env *env, const char *subsystem)
275 {
276 	int len;
277 
278 	len = strlcpy(&env->buf[env->buflen], subsystem,
279 		      sizeof(env->buf) - env->buflen);
280 	if (len >= (sizeof(env->buf) - env->buflen)) {
281 		WARN(1, KERN_ERR "init_uevent_argv: buffer size too small\n");
282 		return -ENOMEM;
283 	}
284 
285 	env->argv[0] = uevent_helper;
286 	env->argv[1] = &env->buf[env->buflen];
287 	env->argv[2] = NULL;
288 
289 	env->buflen += len + 1;
290 	return 0;
291 }
292 
293 static void cleanup_uevent_env(struct subprocess_info *info)
294 {
295 	kfree(info->data);
296 }
297 #endif
298 
299 static int kobject_uevent_net_broadcast(struct kobject *kobj,
300 					struct kobj_uevent_env *env,
301 					const char *action_string,
302 					const char *devpath)
303 {
304 	int retval = 0;
305 #if defined(CONFIG_NET)
306 	struct sk_buff *skb = NULL;
307 	struct uevent_sock *ue_sk;
308 
309 	/* send netlink message */
310 	list_for_each_entry(ue_sk, &uevent_sock_list, list) {
311 		struct sock *uevent_sock = ue_sk->sk;
312 
313 		if (!netlink_has_listeners(uevent_sock, 1))
314 			continue;
315 
316 		if (!skb) {
317 			/* allocate message with the maximum possible size */
318 			size_t len = strlen(action_string) + strlen(devpath) + 2;
319 			char *scratch;
320 
321 			retval = -ENOMEM;
322 			skb = alloc_skb(len + env->buflen, GFP_KERNEL);
323 			if (!skb)
324 				continue;
325 
326 			/* add header */
327 			scratch = skb_put(skb, len);
328 			sprintf(scratch, "%s@%s", action_string, devpath);
329 
330 			skb_put_data(skb, env->buf, env->buflen);
331 
332 			NETLINK_CB(skb).dst_group = 1;
333 		}
334 
335 		retval = netlink_broadcast_filtered(uevent_sock, skb_get(skb),
336 						    0, 1, GFP_KERNEL,
337 						    kobj_bcast_filter,
338 						    kobj);
339 		/* ENOBUFS should be handled in userspace */
340 		if (retval == -ENOBUFS || retval == -ESRCH)
341 			retval = 0;
342 	}
343 	consume_skb(skb);
344 #endif
345 	return retval;
346 }
347 
348 static void zap_modalias_env(struct kobj_uevent_env *env)
349 {
350 	static const char modalias_prefix[] = "MODALIAS=";
351 	size_t len;
352 	int i, j;
353 
354 	for (i = 0; i < env->envp_idx;) {
355 		if (strncmp(env->envp[i], modalias_prefix,
356 			    sizeof(modalias_prefix) - 1)) {
357 			i++;
358 			continue;
359 		}
360 
361 		len = strlen(env->envp[i]) + 1;
362 
363 		if (i != env->envp_idx - 1) {
364 			memmove(env->envp[i], env->envp[i + 1],
365 				env->buflen - len);
366 
367 			for (j = i; j < env->envp_idx - 1; j++)
368 				env->envp[j] = env->envp[j + 1] - len;
369 		}
370 
371 		env->envp_idx--;
372 		env->buflen -= len;
373 	}
374 }
375 
376 /**
377  * kobject_uevent_env - send an uevent with environmental data
378  *
379  * @kobj: struct kobject that the action is happening to
380  * @action: action that is happening
381  * @envp_ext: pointer to environmental data
382  *
383  * Returns 0 if kobject_uevent_env() is completed with success or the
384  * corresponding error when it fails.
385  */
386 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
387 		       char *envp_ext[])
388 {
389 	struct kobj_uevent_env *env;
390 	const char *action_string = kobject_actions[action];
391 	const char *devpath = NULL;
392 	const char *subsystem;
393 	struct kobject *top_kobj;
394 	struct kset *kset;
395 	const struct kset_uevent_ops *uevent_ops;
396 	int i = 0;
397 	int retval = 0;
398 
399 	pr_debug("kobject: '%s' (%p): %s\n",
400 		 kobject_name(kobj), kobj, __func__);
401 
402 	/* search the kset we belong to */
403 	top_kobj = kobj;
404 	while (!top_kobj->kset && top_kobj->parent)
405 		top_kobj = top_kobj->parent;
406 
407 	if (!top_kobj->kset) {
408 		pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
409 			 "without kset!\n", kobject_name(kobj), kobj,
410 			 __func__);
411 		return -EINVAL;
412 	}
413 
414 	kset = top_kobj->kset;
415 	uevent_ops = kset->uevent_ops;
416 
417 	/* skip the event, if uevent_suppress is set*/
418 	if (kobj->uevent_suppress) {
419 		pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
420 				 "caused the event to drop!\n",
421 				 kobject_name(kobj), kobj, __func__);
422 		return 0;
423 	}
424 	/* skip the event, if the filter returns zero. */
425 	if (uevent_ops && uevent_ops->filter)
426 		if (!uevent_ops->filter(kset, kobj)) {
427 			pr_debug("kobject: '%s' (%p): %s: filter function "
428 				 "caused the event to drop!\n",
429 				 kobject_name(kobj), kobj, __func__);
430 			return 0;
431 		}
432 
433 	/* originating subsystem */
434 	if (uevent_ops && uevent_ops->name)
435 		subsystem = uevent_ops->name(kset, kobj);
436 	else
437 		subsystem = kobject_name(&kset->kobj);
438 	if (!subsystem) {
439 		pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
440 			 "event to drop!\n", kobject_name(kobj), kobj,
441 			 __func__);
442 		return 0;
443 	}
444 
445 	/* environment buffer */
446 	env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
447 	if (!env)
448 		return -ENOMEM;
449 
450 	/* complete object path */
451 	devpath = kobject_get_path(kobj, GFP_KERNEL);
452 	if (!devpath) {
453 		retval = -ENOENT;
454 		goto exit;
455 	}
456 
457 	/* default keys */
458 	retval = add_uevent_var(env, "ACTION=%s", action_string);
459 	if (retval)
460 		goto exit;
461 	retval = add_uevent_var(env, "DEVPATH=%s", devpath);
462 	if (retval)
463 		goto exit;
464 	retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
465 	if (retval)
466 		goto exit;
467 
468 	/* keys passed in from the caller */
469 	if (envp_ext) {
470 		for (i = 0; envp_ext[i]; i++) {
471 			retval = add_uevent_var(env, "%s", envp_ext[i]);
472 			if (retval)
473 				goto exit;
474 		}
475 	}
476 
477 	/* let the kset specific function add its stuff */
478 	if (uevent_ops && uevent_ops->uevent) {
479 		retval = uevent_ops->uevent(kset, kobj, env);
480 		if (retval) {
481 			pr_debug("kobject: '%s' (%p): %s: uevent() returned "
482 				 "%d\n", kobject_name(kobj), kobj,
483 				 __func__, retval);
484 			goto exit;
485 		}
486 	}
487 
488 	switch (action) {
489 	case KOBJ_ADD:
490 		/*
491 		 * Mark "add" event so we can make sure we deliver "remove"
492 		 * event to userspace during automatic cleanup. If
493 		 * the object did send an "add" event, "remove" will
494 		 * automatically generated by the core, if not already done
495 		 * by the caller.
496 		 */
497 		kobj->state_add_uevent_sent = 1;
498 		break;
499 
500 	case KOBJ_REMOVE:
501 		kobj->state_remove_uevent_sent = 1;
502 		break;
503 
504 	case KOBJ_UNBIND:
505 		zap_modalias_env(env);
506 		break;
507 
508 	default:
509 		break;
510 	}
511 
512 	mutex_lock(&uevent_sock_mutex);
513 	/* we will send an event, so request a new sequence number */
514 	retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum);
515 	if (retval) {
516 		mutex_unlock(&uevent_sock_mutex);
517 		goto exit;
518 	}
519 	retval = kobject_uevent_net_broadcast(kobj, env, action_string,
520 					      devpath);
521 	mutex_unlock(&uevent_sock_mutex);
522 
523 #ifdef CONFIG_UEVENT_HELPER
524 	/* call uevent_helper, usually only enabled during early boot */
525 	if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
526 		struct subprocess_info *info;
527 
528 		retval = add_uevent_var(env, "HOME=/");
529 		if (retval)
530 			goto exit;
531 		retval = add_uevent_var(env,
532 					"PATH=/sbin:/bin:/usr/sbin:/usr/bin");
533 		if (retval)
534 			goto exit;
535 		retval = init_uevent_argv(env, subsystem);
536 		if (retval)
537 			goto exit;
538 
539 		retval = -ENOMEM;
540 		info = call_usermodehelper_setup(env->argv[0], env->argv,
541 						 env->envp, GFP_KERNEL,
542 						 NULL, cleanup_uevent_env, env);
543 		if (info) {
544 			retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
545 			env = NULL;	/* freed by cleanup_uevent_env */
546 		}
547 	}
548 #endif
549 
550 exit:
551 	kfree(devpath);
552 	kfree(env);
553 	return retval;
554 }
555 EXPORT_SYMBOL_GPL(kobject_uevent_env);
556 
557 /**
558  * kobject_uevent - notify userspace by sending an uevent
559  *
560  * @kobj: struct kobject that the action is happening to
561  * @action: action that is happening
562  *
563  * Returns 0 if kobject_uevent() is completed with success or the
564  * corresponding error when it fails.
565  */
566 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
567 {
568 	return kobject_uevent_env(kobj, action, NULL);
569 }
570 EXPORT_SYMBOL_GPL(kobject_uevent);
571 
572 /**
573  * add_uevent_var - add key value string to the environment buffer
574  * @env: environment buffer structure
575  * @format: printf format for the key=value pair
576  *
577  * Returns 0 if environment variable was added successfully or -ENOMEM
578  * if no space was available.
579  */
580 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
581 {
582 	va_list args;
583 	int len;
584 
585 	if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
586 		WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
587 		return -ENOMEM;
588 	}
589 
590 	va_start(args, format);
591 	len = vsnprintf(&env->buf[env->buflen],
592 			sizeof(env->buf) - env->buflen,
593 			format, args);
594 	va_end(args);
595 
596 	if (len >= (sizeof(env->buf) - env->buflen)) {
597 		WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
598 		return -ENOMEM;
599 	}
600 
601 	env->envp[env->envp_idx++] = &env->buf[env->buflen];
602 	env->buflen += len + 1;
603 	return 0;
604 }
605 EXPORT_SYMBOL_GPL(add_uevent_var);
606 
607 #if defined(CONFIG_NET)
608 static int uevent_net_broadcast(struct sock *usk, struct sk_buff *skb,
609 				struct netlink_ext_ack *extack)
610 {
611 	/* u64 to chars: 2^64 - 1 = 21 chars */
612 	char buf[sizeof("SEQNUM=") + 21];
613 	struct sk_buff *skbc;
614 	int ret;
615 
616 	/* bump and prepare sequence number */
617 	ret = snprintf(buf, sizeof(buf), "SEQNUM=%llu", ++uevent_seqnum);
618 	if (ret < 0 || (size_t)ret >= sizeof(buf))
619 		return -ENOMEM;
620 	ret++;
621 
622 	/* verify message does not overflow */
623 	if ((skb->len + ret) > UEVENT_BUFFER_SIZE) {
624 		NL_SET_ERR_MSG(extack, "uevent message too big");
625 		return -EINVAL;
626 	}
627 
628 	/* copy skb and extend to accommodate sequence number */
629 	skbc = skb_copy_expand(skb, 0, ret, GFP_KERNEL);
630 	if (!skbc)
631 		return -ENOMEM;
632 
633 	/* append sequence number */
634 	skb_put_data(skbc, buf, ret);
635 
636 	/* remove msg header */
637 	skb_pull(skbc, NLMSG_HDRLEN);
638 
639 	/* set portid 0 to inform userspace message comes from kernel */
640 	NETLINK_CB(skbc).portid = 0;
641 	NETLINK_CB(skbc).dst_group = 1;
642 
643 	ret = netlink_broadcast(usk, skbc, 0, 1, GFP_KERNEL);
644 	/* ENOBUFS should be handled in userspace */
645 	if (ret == -ENOBUFS || ret == -ESRCH)
646 		ret = 0;
647 
648 	return ret;
649 }
650 
651 static int uevent_net_rcv_skb(struct sk_buff *skb, struct nlmsghdr *nlh,
652 			      struct netlink_ext_ack *extack)
653 {
654 	struct net *net;
655 	int ret;
656 
657 	if (!nlmsg_data(nlh))
658 		return -EINVAL;
659 
660 	/*
661 	 * Verify that we are allowed to send messages to the target
662 	 * network namespace. The caller must have CAP_SYS_ADMIN in the
663 	 * owning user namespace of the target network namespace.
664 	 */
665 	net = sock_net(NETLINK_CB(skb).sk);
666 	if (!netlink_ns_capable(skb, net->user_ns, CAP_SYS_ADMIN)) {
667 		NL_SET_ERR_MSG(extack, "missing CAP_SYS_ADMIN capability");
668 		return -EPERM;
669 	}
670 
671 	mutex_lock(&uevent_sock_mutex);
672 	ret = uevent_net_broadcast(net->uevent_sock->sk, skb, extack);
673 	mutex_unlock(&uevent_sock_mutex);
674 
675 	return ret;
676 }
677 
678 static void uevent_net_rcv(struct sk_buff *skb)
679 {
680 	netlink_rcv_skb(skb, &uevent_net_rcv_skb);
681 }
682 
683 static int uevent_net_init(struct net *net)
684 {
685 	struct uevent_sock *ue_sk;
686 	struct netlink_kernel_cfg cfg = {
687 		.groups	= 1,
688 		.input = uevent_net_rcv,
689 		.flags	= NL_CFG_F_NONROOT_RECV
690 	};
691 
692 	ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
693 	if (!ue_sk)
694 		return -ENOMEM;
695 
696 	ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
697 	if (!ue_sk->sk) {
698 		printk(KERN_ERR
699 		       "kobject_uevent: unable to create netlink socket!\n");
700 		kfree(ue_sk);
701 		return -ENODEV;
702 	}
703 
704 	net->uevent_sock = ue_sk;
705 
706 	mutex_lock(&uevent_sock_mutex);
707 	list_add_tail(&ue_sk->list, &uevent_sock_list);
708 	mutex_unlock(&uevent_sock_mutex);
709 	return 0;
710 }
711 
712 static void uevent_net_exit(struct net *net)
713 {
714 	struct uevent_sock *ue_sk = net->uevent_sock;
715 
716 	mutex_lock(&uevent_sock_mutex);
717 	list_del(&ue_sk->list);
718 	mutex_unlock(&uevent_sock_mutex);
719 
720 	netlink_kernel_release(ue_sk->sk);
721 	kfree(ue_sk);
722 }
723 
724 static struct pernet_operations uevent_net_ops = {
725 	.init	= uevent_net_init,
726 	.exit	= uevent_net_exit,
727 };
728 
729 static int __init kobject_uevent_init(void)
730 {
731 	return register_pernet_subsys(&uevent_net_ops);
732 }
733 
734 
735 postcore_initcall(kobject_uevent_init);
736 #endif
737