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
33 u64 uevent_seqnum;
34 #ifdef CONFIG_UEVENT_HELPER
35 char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
36 #endif
37
38 struct uevent_sock {
39 struct list_head list;
40 struct sock *sk;
41 };
42
43 #ifdef CONFIG_NET
44 static LIST_HEAD(uevent_sock_list);
45 #endif
46
47 /* This lock protects uevent_seqnum and uevent_sock_list */
48 static DEFINE_MUTEX(uevent_sock_mutex);
49
50 /* the strings here must match the enum in include/linux/kobject.h */
51 static 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
kobject_action_type(const char * buf,size_t count,enum kobject_action * type,const char ** args)62 static 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 }
95 out:
96 return ret;
97 }
98
action_arg_word_end(const char * buf,const char * buf_end,char delim)99 static 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
kobject_action_args(const char * buf,size_t count,struct kobj_uevent_env ** ret_env)114 static 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;
174 out:
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 */
kobject_synth_uevent(struct kobject * kobj,const char * buf,size_t count)192 int 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);
224 out:
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
kobj_usermode_filter(struct kobject * kobj)236 static 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
init_uevent_argv(struct kobj_uevent_env * env,const char * subsystem)252 static 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
cleanup_uevent_env(struct subprocess_info * info)272 static void cleanup_uevent_env(struct subprocess_info *info)
273 {
274 kfree(info->data);
275 }
276 #endif
277
278 #ifdef CONFIG_NET
alloc_uevent_skb(struct kobj_uevent_env * env,const char * action_string,const char * devpath)279 static 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
uevent_net_broadcast_untagged(struct kobj_uevent_env * env,const char * action_string,const char * devpath)309 static 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
uevent_net_broadcast_tagged(struct sock * usk,struct kobj_uevent_env * env,const char * action_string,const char * devpath)342 static 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
kobject_uevent_net_broadcast(struct kobject * kobj,struct kobj_uevent_env * env,const char * action_string,const char * devpath)381 static 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
zap_modalias_env(struct kobj_uevent_env * env)419 static 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 */
kobject_uevent_env(struct kobject * kobj,enum kobject_action action,char * envp_ext[])457 int 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(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(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(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
624 exit:
625 kfree(devpath);
626 kfree(env);
627 return retval;
628 }
629 EXPORT_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 */
kobject_uevent(struct kobject * kobj,enum kobject_action action)640 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
641 {
642 return kobject_uevent_env(kobj, action, NULL);
643 }
644 EXPORT_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 */
add_uevent_var(struct kobj_uevent_env * env,const char * format,...)654 int 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 }
679 EXPORT_SYMBOL_GPL(add_uevent_var);
680
681 #if defined(CONFIG_NET)
uevent_net_broadcast(struct sock * usk,struct sk_buff * skb,struct netlink_ext_ack * extack)682 static 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
uevent_net_rcv_skb(struct sk_buff * skb,struct nlmsghdr * nlh,struct netlink_ext_ack * extack)725 static 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
uevent_net_rcv(struct sk_buff * skb)752 static void uevent_net_rcv(struct sk_buff *skb)
753 {
754 netlink_rcv_skb(skb, &uevent_net_rcv_skb);
755 }
756
uevent_net_init(struct net * net)757 static 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
uevent_net_exit(struct net * net)789 static 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
803 static struct pernet_operations uevent_net_ops = {
804 .init = uevent_net_init,
805 .exit = uevent_net_exit,
806 };
807
kobject_uevent_init(void)808 static int __init kobject_uevent_init(void)
809 {
810 return register_pernet_subsys(&uevent_net_ops);
811 }
812
813
814 postcore_initcall(kobject_uevent_init);
815 #endif
816