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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 memmove(env->envp[i], env->envp[i + 1],
436 env->buflen - len);
437
438 for (j = i; j < env->envp_idx - 1; j++)
439 env->envp[j] = env->envp[j + 1] - len;
440 }
441
442 env->envp_idx--;
443 env->buflen -= len;
444 }
445}
446
447/**
448 * kobject_uevent_env - send an uevent with environmental data
449 *
450 * @kobj: struct kobject that the action is happening to
451 * @action: action that is happening
452 * @envp_ext: pointer to environmental data
453 *
454 * Returns 0 if kobject_uevent_env() is completed with success or the
455 * corresponding error when it fails.
456 */
457int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
458 char *envp_ext[])
459{
460 struct kobj_uevent_env *env;
461 const char *action_string = kobject_actions[action];
462 const char *devpath = NULL;
463 const char *subsystem;
464 struct kobject *top_kobj;
465 struct kset *kset;
466 const struct kset_uevent_ops *uevent_ops;
467 int i = 0;
468 int retval = 0;
469
470 /*
471 * Mark "remove" event done regardless of result, for some subsystems
472 * do not want to re-trigger "remove" event via automatic cleanup.
473 */
474 if (action == KOBJ_REMOVE)
475 kobj->state_remove_uevent_sent = 1;
476
477 pr_debug("kobject: '%s' (%p): %s\n",
478 kobject_name(kobj), kobj, __func__);
479
480 /* search the kset we belong to */
481 top_kobj = kobj;
482 while (!top_kobj->kset && top_kobj->parent)
483 top_kobj = top_kobj->parent;
484
485 if (!top_kobj->kset) {
486 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
487 "without kset!\n", kobject_name(kobj), kobj,
488 __func__);
489 return -EINVAL;
490 }
491
492 kset = top_kobj->kset;
493 uevent_ops = kset->uevent_ops;
494
495 /* skip the event, if uevent_suppress is set*/
496 if (kobj->uevent_suppress) {
497 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
498 "caused the event to drop!\n",
499 kobject_name(kobj), kobj, __func__);
500 return 0;
501 }
502 /* skip the event, if the filter returns zero. */
503 if (uevent_ops && uevent_ops->filter)
504 if (!uevent_ops->filter(kset, kobj)) {
505 pr_debug("kobject: '%s' (%p): %s: filter function "
506 "caused the event to drop!\n",
507 kobject_name(kobj), kobj, __func__);
508 return 0;
509 }
510
511 /* originating subsystem */
512 if (uevent_ops && uevent_ops->name)
513 subsystem = uevent_ops->name(kset, kobj);
514 else
515 subsystem = kobject_name(&kset->kobj);
516 if (!subsystem) {
517 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
518 "event to drop!\n", kobject_name(kobj), kobj,
519 __func__);
520 return 0;
521 }
522
523 /* environment buffer */
524 env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
525 if (!env)
526 return -ENOMEM;
527
528 /* complete object path */
529 devpath = kobject_get_path(kobj, GFP_KERNEL);
530 if (!devpath) {
531 retval = -ENOENT;
532 goto exit;
533 }
534
535 /* default keys */
536 retval = add_uevent_var(env, "ACTION=%s", action_string);
537 if (retval)
538 goto exit;
539 retval = add_uevent_var(env, "DEVPATH=%s", devpath);
540 if (retval)
541 goto exit;
542 retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
543 if (retval)
544 goto exit;
545
546 /* keys passed in from the caller */
547 if (envp_ext) {
548 for (i = 0; envp_ext[i]; i++) {
549 retval = add_uevent_var(env, "%s", envp_ext[i]);
550 if (retval)
551 goto exit;
552 }
553 }
554
555 /* let the kset specific function add its stuff */
556 if (uevent_ops && uevent_ops->uevent) {
557 retval = uevent_ops->uevent(kset, kobj, env);
558 if (retval) {
559 pr_debug("kobject: '%s' (%p): %s: uevent() returned "
560 "%d\n", kobject_name(kobj), kobj,
561 __func__, retval);
562 goto exit;
563 }
564 }
565
566 switch (action) {
567 case KOBJ_ADD:
568 /*
569 * Mark "add" event so we can make sure we deliver "remove"
570 * event to userspace during automatic cleanup. If
571 * the object did send an "add" event, "remove" will
572 * automatically generated by the core, if not already done
573 * by the caller.
574 */
575 kobj->state_add_uevent_sent = 1;
576 break;
577
578 case KOBJ_UNBIND:
579 zap_modalias_env(env);
580 break;
581
582 default:
583 break;
584 }
585
586 mutex_lock(&uevent_sock_mutex);
587 /* we will send an event, so request a new sequence number */
588 retval = add_uevent_var(env, "SEQNUM=%llu", ++uevent_seqnum);
589 if (retval) {
590 mutex_unlock(&uevent_sock_mutex);
591 goto exit;
592 }
593 retval = kobject_uevent_net_broadcast(kobj, env, action_string,
594 devpath);
595 mutex_unlock(&uevent_sock_mutex);
596
597#ifdef CONFIG_UEVENT_HELPER
598 /* call uevent_helper, usually only enabled during early boot */
599 if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
600 struct subprocess_info *info;
601
602 retval = add_uevent_var(env, "HOME=/");
603 if (retval)
604 goto exit;
605 retval = add_uevent_var(env,
606 "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
607 if (retval)
608 goto exit;
609 retval = init_uevent_argv(env, subsystem);
610 if (retval)
611 goto exit;
612
613 retval = -ENOMEM;
614 info = call_usermodehelper_setup(env->argv[0], env->argv,
615 env->envp, GFP_KERNEL,
616 NULL, cleanup_uevent_env, env);
617 if (info) {
618 retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
619 env = NULL; /* freed by cleanup_uevent_env */
620 }
621 }
622#endif
623
624exit:
625 kfree(devpath);
626 kfree(env);
627 return retval;
628}
629EXPORT_SYMBOL_GPL(kobject_uevent_env);
630
631/**
632 * kobject_uevent - notify userspace by sending an uevent
633 *
634 * @kobj: struct kobject that the action is happening to
635 * @action: action that is happening
636 *
637 * Returns 0 if kobject_uevent() is completed with success or the
638 * corresponding error when it fails.
639 */
640int kobject_uevent(struct kobject *kobj, enum kobject_action action)
641{
642 return kobject_uevent_env(kobj, action, NULL);
643}
644EXPORT_SYMBOL_GPL(kobject_uevent);
645
646/**
647 * add_uevent_var - add key value string to the environment buffer
648 * @env: environment buffer structure
649 * @format: printf format for the key=value pair
650 *
651 * Returns 0 if environment variable was added successfully or -ENOMEM
652 * if no space was available.
653 */
654int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
655{
656 va_list args;
657 int len;
658
659 if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
660 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
661 return -ENOMEM;
662 }
663
664 va_start(args, format);
665 len = vsnprintf(&env->buf[env->buflen],
666 sizeof(env->buf) - env->buflen,
667 format, args);
668 va_end(args);
669
670 if (len >= (sizeof(env->buf) - env->buflen)) {
671 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
672 return -ENOMEM;
673 }
674
675 env->envp[env->envp_idx++] = &env->buf[env->buflen];
676 env->buflen += len + 1;
677 return 0;
678}
679EXPORT_SYMBOL_GPL(add_uevent_var);
680
681#if defined(CONFIG_NET)
682static int uevent_net_broadcast(struct sock *usk, struct sk_buff *skb,
683 struct netlink_ext_ack *extack)
684{
685 /* u64 to chars: 2^64 - 1 = 21 chars */
686 char buf[sizeof("SEQNUM=") + 21];
687 struct sk_buff *skbc;
688 int ret;
689
690 /* bump and prepare sequence number */
691 ret = snprintf(buf, sizeof(buf), "SEQNUM=%llu", ++uevent_seqnum);
692 if (ret < 0 || (size_t)ret >= sizeof(buf))
693 return -ENOMEM;
694 ret++;
695
696 /* verify message does not overflow */
697 if ((skb->len + ret) > UEVENT_BUFFER_SIZE) {
698 NL_SET_ERR_MSG(extack, "uevent message too big");
699 return -EINVAL;
700 }
701
702 /* copy skb and extend to accommodate sequence number */
703 skbc = skb_copy_expand(skb, 0, ret, GFP_KERNEL);
704 if (!skbc)
705 return -ENOMEM;
706
707 /* append sequence number */
708 skb_put_data(skbc, buf, ret);
709
710 /* remove msg header */
711 skb_pull(skbc, NLMSG_HDRLEN);
712
713 /* set portid 0 to inform userspace message comes from kernel */
714 NETLINK_CB(skbc).portid = 0;
715 NETLINK_CB(skbc).dst_group = 1;
716
717 ret = netlink_broadcast(usk, skbc, 0, 1, GFP_KERNEL);
718 /* ENOBUFS should be handled in userspace */
719 if (ret == -ENOBUFS || ret == -ESRCH)
720 ret = 0;
721
722 return ret;
723}
724
725static int uevent_net_rcv_skb(struct sk_buff *skb, struct nlmsghdr *nlh,
726 struct netlink_ext_ack *extack)
727{
728 struct net *net;
729 int ret;
730
731 if (!nlmsg_data(nlh))
732 return -EINVAL;
733
734 /*
735 * Verify that we are allowed to send messages to the target
736 * network namespace. The caller must have CAP_SYS_ADMIN in the
737 * owning user namespace of the target network namespace.
738 */
739 net = sock_net(NETLINK_CB(skb).sk);
740 if (!netlink_ns_capable(skb, net->user_ns, CAP_SYS_ADMIN)) {
741 NL_SET_ERR_MSG(extack, "missing CAP_SYS_ADMIN capability");
742 return -EPERM;
743 }
744
745 mutex_lock(&uevent_sock_mutex);
746 ret = uevent_net_broadcast(net->uevent_sock->sk, skb, extack);
747 mutex_unlock(&uevent_sock_mutex);
748
749 return ret;
750}
751
752static void uevent_net_rcv(struct sk_buff *skb)
753{
754 netlink_rcv_skb(skb, &uevent_net_rcv_skb);
755}
756
757static int uevent_net_init(struct net *net)
758{
759 struct uevent_sock *ue_sk;
760 struct netlink_kernel_cfg cfg = {
761 .groups = 1,
762 .input = uevent_net_rcv,
763 .flags = NL_CFG_F_NONROOT_RECV
764 };
765
766 ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
767 if (!ue_sk)
768 return -ENOMEM;
769
770 ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
771 if (!ue_sk->sk) {
772 pr_err("kobject_uevent: unable to create netlink socket!\n");
773 kfree(ue_sk);
774 return -ENODEV;
775 }
776
777 net->uevent_sock = ue_sk;
778
779 /* Restrict uevents to initial user namespace. */
780 if (sock_net(ue_sk->sk)->user_ns == &init_user_ns) {
781 mutex_lock(&uevent_sock_mutex);
782 list_add_tail(&ue_sk->list, &uevent_sock_list);
783 mutex_unlock(&uevent_sock_mutex);
784 }
785
786 return 0;
787}
788
789static void uevent_net_exit(struct net *net)
790{
791 struct uevent_sock *ue_sk = net->uevent_sock;
792
793 if (sock_net(ue_sk->sk)->user_ns == &init_user_ns) {
794 mutex_lock(&uevent_sock_mutex);
795 list_del(&ue_sk->list);
796 mutex_unlock(&uevent_sock_mutex);
797 }
798
799 netlink_kernel_release(ue_sk->sk);
800 kfree(ue_sk);
801}
802
803static struct pernet_operations uevent_net_ops = {
804 .init = uevent_net_init,
805 .exit = uevent_net_exit,
806};
807
808static int __init kobject_uevent_init(void)
809{
810 return register_pernet_subsys(&uevent_net_ops);
811}
812
813
814postcore_initcall(kobject_uevent_init);
815#endif
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
33atomic64_t 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/* This lock protects uevent_sock_list */
46static DEFINE_MUTEX(uevent_sock_mutex);
47#endif
48
49/* the strings here must match the enum in include/linux/kobject.h */
50static 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
61static 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 }
94out:
95 return ret;
96}
97
98static 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
113static 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;
173out:
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 */
191int 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";
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";
215 goto out;
216 }
217
218 if (r)
219 goto out;
220
221 r = kobject_uevent_env(kobj, action, env->envp);
222 kfree(env);
223out:
224 if (r) {
225 devpath = kobject_get_path(kobj, GFP_KERNEL);
226 pr_warn("synth uevent: %s: %s\n",
227 devpath ?: "unknown device",
228 msg ?: "failed to send uevent");
229 kfree(devpath);
230 }
231 return r;
232}
233
234#ifdef CONFIG_UEVENT_HELPER
235static int kobj_usermode_filter(struct kobject *kobj)
236{
237 const struct kobj_ns_type_operations *ops;
238
239 ops = kobj_ns_ops(kobj);
240 if (ops) {
241 const void *init_ns, *ns;
242
243 ns = kobj->ktype->namespace(kobj);
244 init_ns = ops->initial_ns();
245 return ns != init_ns;
246 }
247
248 return 0;
249}
250
251static int init_uevent_argv(struct kobj_uevent_env *env, const char *subsystem)
252{
253 int buffer_size = sizeof(env->buf) - env->buflen;
254 int len;
255
256 len = strscpy(&env->buf[env->buflen], subsystem, buffer_size);
257 if (len < 0) {
258 pr_warn("%s: insufficient buffer space (%u left) for %s\n",
259 __func__, buffer_size, subsystem);
260 return -ENOMEM;
261 }
262
263 env->argv[0] = uevent_helper;
264 env->argv[1] = &env->buf[env->buflen];
265 env->argv[2] = NULL;
266
267 env->buflen += len + 1;
268 return 0;
269}
270
271static void cleanup_uevent_env(struct subprocess_info *info)
272{
273 kfree(info->data);
274}
275#endif
276
277#ifdef CONFIG_NET
278static struct sk_buff *alloc_uevent_skb(struct kobj_uevent_env *env,
279 const char *action_string,
280 const char *devpath)
281{
282 struct netlink_skb_parms *parms;
283 struct sk_buff *skb = NULL;
284 char *scratch;
285 size_t len;
286
287 /* allocate message with maximum possible size */
288 len = strlen(action_string) + strlen(devpath) + 2;
289 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
290 if (!skb)
291 return NULL;
292
293 /* add header */
294 scratch = skb_put(skb, len);
295 sprintf(scratch, "%s@%s", action_string, devpath);
296
297 skb_put_data(skb, env->buf, env->buflen);
298
299 parms = &NETLINK_CB(skb);
300 parms->creds.uid = GLOBAL_ROOT_UID;
301 parms->creds.gid = GLOBAL_ROOT_GID;
302 parms->dst_group = 1;
303 parms->portid = 0;
304
305 return skb;
306}
307
308static int uevent_net_broadcast_untagged(struct kobj_uevent_env *env,
309 const char *action_string,
310 const char *devpath)
311{
312 struct sk_buff *skb = NULL;
313 struct uevent_sock *ue_sk;
314 int retval = 0;
315
316 /* send netlink message */
317 mutex_lock(&uevent_sock_mutex);
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 mutex_unlock(&uevent_sock_mutex);
338 consume_skb(skb);
339
340 return retval;
341}
342
343static int uevent_net_broadcast_tagged(struct sock *usk,
344 struct kobj_uevent_env *env,
345 const char *action_string,
346 const char *devpath)
347{
348 struct user_namespace *owning_user_ns = sock_net(usk)->user_ns;
349 struct sk_buff *skb = NULL;
350 int ret = 0;
351
352 skb = alloc_uevent_skb(env, action_string, devpath);
353 if (!skb)
354 return -ENOMEM;
355
356 /* fix credentials */
357 if (owning_user_ns != &init_user_ns) {
358 struct netlink_skb_parms *parms = &NETLINK_CB(skb);
359 kuid_t root_uid;
360 kgid_t root_gid;
361
362 /* fix uid */
363 root_uid = make_kuid(owning_user_ns, 0);
364 if (uid_valid(root_uid))
365 parms->creds.uid = root_uid;
366
367 /* fix gid */
368 root_gid = make_kgid(owning_user_ns, 0);
369 if (gid_valid(root_gid))
370 parms->creds.gid = root_gid;
371 }
372
373 ret = netlink_broadcast(usk, skb, 0, 1, GFP_KERNEL);
374 /* ENOBUFS should be handled in userspace */
375 if (ret == -ENOBUFS || ret == -ESRCH)
376 ret = 0;
377
378 return ret;
379}
380#endif
381
382static int kobject_uevent_net_broadcast(struct kobject *kobj,
383 struct kobj_uevent_env *env,
384 const char *action_string,
385 const char *devpath)
386{
387 int ret = 0;
388
389#ifdef CONFIG_NET
390 const struct kobj_ns_type_operations *ops;
391 const struct net *net = NULL;
392
393 ops = kobj_ns_ops(kobj);
394 if (!ops && kobj->kset) {
395 struct kobject *ksobj = &kobj->kset->kobj;
396
397 if (ksobj->parent != NULL)
398 ops = kobj_ns_ops(ksobj->parent);
399 }
400
401 /* kobjects currently only carry network namespace tags and they
402 * are the only tag relevant here since we want to decide which
403 * network namespaces to broadcast the uevent into.
404 */
405 if (ops && ops->netlink_ns && kobj->ktype->namespace)
406 if (ops->type == KOBJ_NS_TYPE_NET)
407 net = kobj->ktype->namespace(kobj);
408
409 if (!net)
410 ret = uevent_net_broadcast_untagged(env, action_string,
411 devpath);
412 else
413 ret = uevent_net_broadcast_tagged(net->uevent_sock->sk, env,
414 action_string, devpath);
415#endif
416
417 return ret;
418}
419
420static void zap_modalias_env(struct kobj_uevent_env *env)
421{
422 static const char modalias_prefix[] = "MODALIAS=";
423 size_t len;
424 int i, j;
425
426 for (i = 0; i < env->envp_idx;) {
427 if (strncmp(env->envp[i], modalias_prefix,
428 sizeof(modalias_prefix) - 1)) {
429 i++;
430 continue;
431 }
432
433 len = strlen(env->envp[i]) + 1;
434
435 if (i != env->envp_idx - 1) {
436 /* @env->envp[] contains pointers to @env->buf[]
437 * with @env->buflen chars, and we are removing
438 * variable MODALIAS here pointed by @env->envp[i]
439 * with length @len as shown below:
440 *
441 * 0 @env->buf[] @env->buflen
442 * ---------------------------------------------
443 * ^ ^ ^ ^
444 * | |-> @len <-| target block |
445 * @env->envp[0] @env->envp[i] @env->envp[i + 1]
446 *
447 * so the "target block" indicated above is moved
448 * backward by @len, and its right size is
449 * @env->buflen - (@env->envp[i + 1] - @env->envp[0]).
450 */
451 memmove(env->envp[i], env->envp[i + 1],
452 env->buflen - (env->envp[i + 1] - env->envp[0]));
453
454 for (j = i; j < env->envp_idx - 1; j++)
455 env->envp[j] = env->envp[j + 1] - len;
456 }
457
458 env->envp_idx--;
459 env->buflen -= len;
460 }
461}
462
463/**
464 * kobject_uevent_env - send an uevent with environmental data
465 *
466 * @kobj: struct kobject that the action is happening to
467 * @action: action that is happening
468 * @envp_ext: pointer to environmental data
469 *
470 * Returns 0 if kobject_uevent_env() is completed with success or the
471 * corresponding error when it fails.
472 */
473int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
474 char *envp_ext[])
475{
476 struct kobj_uevent_env *env;
477 const char *action_string = kobject_actions[action];
478 const char *devpath = NULL;
479 const char *subsystem;
480 struct kobject *top_kobj;
481 struct kset *kset;
482 const struct kset_uevent_ops *uevent_ops;
483 int i = 0;
484 int retval = 0;
485
486 /*
487 * Mark "remove" event done regardless of result, for some subsystems
488 * do not want to re-trigger "remove" event via automatic cleanup.
489 */
490 if (action == KOBJ_REMOVE)
491 kobj->state_remove_uevent_sent = 1;
492
493 pr_debug("kobject: '%s' (%p): %s\n",
494 kobject_name(kobj), kobj, __func__);
495
496 /* search the kset we belong to */
497 top_kobj = kobj;
498 while (!top_kobj->kset && top_kobj->parent)
499 top_kobj = top_kobj->parent;
500
501 if (!top_kobj->kset) {
502 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
503 "without kset!\n", kobject_name(kobj), kobj,
504 __func__);
505 return -EINVAL;
506 }
507
508 kset = top_kobj->kset;
509 uevent_ops = kset->uevent_ops;
510
511 /* skip the event, if uevent_suppress is set*/
512 if (kobj->uevent_suppress) {
513 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
514 "caused the event to drop!\n",
515 kobject_name(kobj), kobj, __func__);
516 return 0;
517 }
518 /* skip the event, if the filter returns zero. */
519 if (uevent_ops && uevent_ops->filter)
520 if (!uevent_ops->filter(kobj)) {
521 pr_debug("kobject: '%s' (%p): %s: filter function "
522 "caused the event to drop!\n",
523 kobject_name(kobj), kobj, __func__);
524 return 0;
525 }
526
527 /* originating subsystem */
528 if (uevent_ops && uevent_ops->name)
529 subsystem = uevent_ops->name(kobj);
530 else
531 subsystem = kobject_name(&kset->kobj);
532 if (!subsystem) {
533 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
534 "event to drop!\n", kobject_name(kobj), kobj,
535 __func__);
536 return 0;
537 }
538
539 /* environment buffer */
540 env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
541 if (!env)
542 return -ENOMEM;
543
544 /* complete object path */
545 devpath = kobject_get_path(kobj, GFP_KERNEL);
546 if (!devpath) {
547 retval = -ENOENT;
548 goto exit;
549 }
550
551 /* default keys */
552 retval = add_uevent_var(env, "ACTION=%s", action_string);
553 if (retval)
554 goto exit;
555 retval = add_uevent_var(env, "DEVPATH=%s", devpath);
556 if (retval)
557 goto exit;
558 retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
559 if (retval)
560 goto exit;
561
562 /* keys passed in from the caller */
563 if (envp_ext) {
564 for (i = 0; envp_ext[i]; i++) {
565 retval = add_uevent_var(env, "%s", envp_ext[i]);
566 if (retval)
567 goto exit;
568 }
569 }
570
571 /* let the kset specific function add its stuff */
572 if (uevent_ops && uevent_ops->uevent) {
573 retval = uevent_ops->uevent(kobj, env);
574 if (retval) {
575 pr_debug("kobject: '%s' (%p): %s: uevent() returned "
576 "%d\n", kobject_name(kobj), kobj,
577 __func__, retval);
578 goto exit;
579 }
580 }
581
582 switch (action) {
583 case KOBJ_ADD:
584 /*
585 * Mark "add" event so we can make sure we deliver "remove"
586 * event to userspace during automatic cleanup. If
587 * the object did send an "add" event, "remove" will
588 * automatically generated by the core, if not already done
589 * by the caller.
590 */
591 kobj->state_add_uevent_sent = 1;
592 break;
593
594 case KOBJ_UNBIND:
595 zap_modalias_env(env);
596 break;
597
598 default:
599 break;
600 }
601
602 /* we will send an event, so request a new sequence number */
603 retval = add_uevent_var(env, "SEQNUM=%llu",
604 atomic64_inc_return(&uevent_seqnum));
605 if (retval)
606 goto exit;
607
608 retval = kobject_uevent_net_broadcast(kobj, env, action_string,
609 devpath);
610
611#ifdef CONFIG_UEVENT_HELPER
612 /* call uevent_helper, usually only enabled during early boot */
613 if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
614 struct subprocess_info *info;
615
616 retval = add_uevent_var(env, "HOME=/");
617 if (retval)
618 goto exit;
619 retval = add_uevent_var(env,
620 "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
621 if (retval)
622 goto exit;
623 retval = init_uevent_argv(env, subsystem);
624 if (retval)
625 goto exit;
626
627 retval = -ENOMEM;
628 info = call_usermodehelper_setup(env->argv[0], env->argv,
629 env->envp, GFP_KERNEL,
630 NULL, cleanup_uevent_env, env);
631 if (info) {
632 retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
633 env = NULL; /* freed by cleanup_uevent_env */
634 }
635 }
636#endif
637
638exit:
639 kfree(devpath);
640 kfree(env);
641 return retval;
642}
643EXPORT_SYMBOL_GPL(kobject_uevent_env);
644
645/**
646 * kobject_uevent - notify userspace by sending an uevent
647 *
648 * @kobj: struct kobject that the action is happening to
649 * @action: action that is happening
650 *
651 * Returns 0 if kobject_uevent() is completed with success or the
652 * corresponding error when it fails.
653 */
654int kobject_uevent(struct kobject *kobj, enum kobject_action action)
655{
656 return kobject_uevent_env(kobj, action, NULL);
657}
658EXPORT_SYMBOL_GPL(kobject_uevent);
659
660/**
661 * add_uevent_var - add key value string to the environment buffer
662 * @env: environment buffer structure
663 * @format: printf format for the key=value pair
664 *
665 * Returns 0 if environment variable was added successfully or -ENOMEM
666 * if no space was available.
667 */
668int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
669{
670 va_list args;
671 int len;
672
673 if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
674 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
675 return -ENOMEM;
676 }
677
678 va_start(args, format);
679 len = vsnprintf(&env->buf[env->buflen],
680 sizeof(env->buf) - env->buflen,
681 format, args);
682 va_end(args);
683
684 if (len >= (sizeof(env->buf) - env->buflen)) {
685 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
686 return -ENOMEM;
687 }
688
689 env->envp[env->envp_idx++] = &env->buf[env->buflen];
690 env->buflen += len + 1;
691 return 0;
692}
693EXPORT_SYMBOL_GPL(add_uevent_var);
694
695#if defined(CONFIG_NET)
696static int uevent_net_broadcast(struct sock *usk, struct sk_buff *skb,
697 struct netlink_ext_ack *extack)
698{
699 /* u64 to chars: 2^64 - 1 = 21 chars */
700 char buf[sizeof("SEQNUM=") + 21];
701 struct sk_buff *skbc;
702 int ret;
703
704 /* bump and prepare sequence number */
705 ret = snprintf(buf, sizeof(buf), "SEQNUM=%llu",
706 atomic64_inc_return(&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 ret = uevent_net_broadcast(net->uevent_sock->sk, skb, extack);
761
762 return ret;
763}
764
765static void uevent_net_rcv(struct sk_buff *skb)
766{
767 netlink_rcv_skb(skb, &uevent_net_rcv_skb);
768}
769
770static int uevent_net_init(struct net *net)
771{
772 struct uevent_sock *ue_sk;
773 struct netlink_kernel_cfg cfg = {
774 .groups = 1,
775 .input = uevent_net_rcv,
776 .flags = NL_CFG_F_NONROOT_RECV
777 };
778
779 ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
780 if (!ue_sk)
781 return -ENOMEM;
782
783 ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
784 if (!ue_sk->sk) {
785 pr_err("kobject_uevent: unable to create netlink socket!\n");
786 kfree(ue_sk);
787 return -ENODEV;
788 }
789
790 net->uevent_sock = ue_sk;
791
792 /* Restrict uevents to initial user namespace. */
793 if (sock_net(ue_sk->sk)->user_ns == &init_user_ns) {
794 mutex_lock(&uevent_sock_mutex);
795 list_add_tail(&ue_sk->list, &uevent_sock_list);
796 mutex_unlock(&uevent_sock_mutex);
797 }
798
799 return 0;
800}
801
802static void uevent_net_exit(struct net *net)
803{
804 struct uevent_sock *ue_sk = net->uevent_sock;
805
806 if (sock_net(ue_sk->sk)->user_ns == &init_user_ns) {
807 mutex_lock(&uevent_sock_mutex);
808 list_del(&ue_sk->list);
809 mutex_unlock(&uevent_sock_mutex);
810 }
811
812 netlink_kernel_release(ue_sk->sk);
813 kfree(ue_sk);
814}
815
816static struct pernet_operations uevent_net_ops = {
817 .init = uevent_net_init,
818 .exit = uevent_net_exit,
819};
820
821static int __init kobject_uevent_init(void)
822{
823 return register_pernet_subsys(&uevent_net_ops);
824}
825
826
827postcore_initcall(kobject_uevent_init);
828#endif