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 len;
255
256 len = strlcpy(&env->buf[env->buflen], subsystem,
257 sizeof(env->buf) - env->buflen);
258 if (len >= (sizeof(env->buf) - env->buflen)) {
259 WARN(1, KERN_ERR "init_uevent_argv: buffer size too small\n");
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
cleanup_uevent_env(struct subprocess_info * info)271 static void cleanup_uevent_env(struct subprocess_info *info)
272 {
273 kfree(info->data);
274 }
275 #endif
276
277 #ifdef CONFIG_NET
alloc_uevent_skb(struct kobj_uevent_env * env,const char * action_string,const char * devpath)278 static 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
uevent_net_broadcast_untagged(struct kobj_uevent_env * env,const char * action_string,const char * devpath)308 static 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 list_for_each_entry(ue_sk, &uevent_sock_list, list) {
318 struct sock *uevent_sock = ue_sk->sk;
319
320 if (!netlink_has_listeners(uevent_sock, 1))
321 continue;
322
323 if (!skb) {
324 retval = -ENOMEM;
325 skb = alloc_uevent_skb(env, action_string, devpath);
326 if (!skb)
327 continue;
328 }
329
330 retval = netlink_broadcast(uevent_sock, skb_get(skb), 0, 1,
331 GFP_KERNEL);
332 /* ENOBUFS should be handled in userspace */
333 if (retval == -ENOBUFS || retval == -ESRCH)
334 retval = 0;
335 }
336 consume_skb(skb);
337
338 return retval;
339 }
340
uevent_net_broadcast_tagged(struct sock * usk,struct kobj_uevent_env * env,const char * action_string,const char * devpath)341 static int uevent_net_broadcast_tagged(struct sock *usk,
342 struct kobj_uevent_env *env,
343 const char *action_string,
344 const char *devpath)
345 {
346 struct user_namespace *owning_user_ns = sock_net(usk)->user_ns;
347 struct sk_buff *skb = NULL;
348 int ret = 0;
349
350 skb = alloc_uevent_skb(env, action_string, devpath);
351 if (!skb)
352 return -ENOMEM;
353
354 /* fix credentials */
355 if (owning_user_ns != &init_user_ns) {
356 struct netlink_skb_parms *parms = &NETLINK_CB(skb);
357 kuid_t root_uid;
358 kgid_t root_gid;
359
360 /* fix uid */
361 root_uid = make_kuid(owning_user_ns, 0);
362 if (uid_valid(root_uid))
363 parms->creds.uid = root_uid;
364
365 /* fix gid */
366 root_gid = make_kgid(owning_user_ns, 0);
367 if (gid_valid(root_gid))
368 parms->creds.gid = root_gid;
369 }
370
371 ret = netlink_broadcast(usk, skb, 0, 1, GFP_KERNEL);
372 /* ENOBUFS should be handled in userspace */
373 if (ret == -ENOBUFS || ret == -ESRCH)
374 ret = 0;
375
376 return ret;
377 }
378 #endif
379
kobject_uevent_net_broadcast(struct kobject * kobj,struct kobj_uevent_env * env,const char * action_string,const char * devpath)380 static int kobject_uevent_net_broadcast(struct kobject *kobj,
381 struct kobj_uevent_env *env,
382 const char *action_string,
383 const char *devpath)
384 {
385 int ret = 0;
386
387 #ifdef CONFIG_NET
388 const struct kobj_ns_type_operations *ops;
389 const struct net *net = NULL;
390
391 ops = kobj_ns_ops(kobj);
392 if (!ops && kobj->kset) {
393 struct kobject *ksobj = &kobj->kset->kobj;
394
395 if (ksobj->parent != NULL)
396 ops = kobj_ns_ops(ksobj->parent);
397 }
398
399 /* kobjects currently only carry network namespace tags and they
400 * are the only tag relevant here since we want to decide which
401 * network namespaces to broadcast the uevent into.
402 */
403 if (ops && ops->netlink_ns && kobj->ktype->namespace)
404 if (ops->type == KOBJ_NS_TYPE_NET)
405 net = kobj->ktype->namespace(kobj);
406
407 if (!net)
408 ret = uevent_net_broadcast_untagged(env, action_string,
409 devpath);
410 else
411 ret = uevent_net_broadcast_tagged(net->uevent_sock->sk, env,
412 action_string, devpath);
413 #endif
414
415 return ret;
416 }
417
zap_modalias_env(struct kobj_uevent_env * env)418 static void zap_modalias_env(struct kobj_uevent_env *env)
419 {
420 static const char modalias_prefix[] = "MODALIAS=";
421 size_t len;
422 int i, j;
423
424 for (i = 0; i < env->envp_idx;) {
425 if (strncmp(env->envp[i], modalias_prefix,
426 sizeof(modalias_prefix) - 1)) {
427 i++;
428 continue;
429 }
430
431 len = strlen(env->envp[i]) + 1;
432
433 if (i != env->envp_idx - 1) {
434 memmove(env->envp[i], env->envp[i + 1],
435 env->buflen - len);
436
437 for (j = i; j < env->envp_idx - 1; j++)
438 env->envp[j] = env->envp[j + 1] - len;
439 }
440
441 env->envp_idx--;
442 env->buflen -= len;
443 }
444 }
445
446 /**
447 * kobject_uevent_env - send an uevent with environmental data
448 *
449 * @kobj: struct kobject that the action is happening to
450 * @action: action that is happening
451 * @envp_ext: pointer to environmental data
452 *
453 * Returns 0 if kobject_uevent_env() is completed with success or the
454 * corresponding error when it fails.
455 */
kobject_uevent_env(struct kobject * kobj,enum kobject_action action,char * envp_ext[])456 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
457 char *envp_ext[])
458 {
459 struct kobj_uevent_env *env;
460 const char *action_string = kobject_actions[action];
461 const char *devpath = NULL;
462 const char *subsystem;
463 struct kobject *top_kobj;
464 struct kset *kset;
465 const struct kset_uevent_ops *uevent_ops;
466 int i = 0;
467 int retval = 0;
468
469 /*
470 * Mark "remove" event done regardless of result, for some subsystems
471 * do not want to re-trigger "remove" event via automatic cleanup.
472 */
473 if (action == KOBJ_REMOVE)
474 kobj->state_remove_uevent_sent = 1;
475
476 pr_debug("kobject: '%s' (%p): %s\n",
477 kobject_name(kobj), kobj, __func__);
478
479 /* search the kset we belong to */
480 top_kobj = kobj;
481 while (!top_kobj->kset && top_kobj->parent)
482 top_kobj = top_kobj->parent;
483
484 if (!top_kobj->kset) {
485 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
486 "without kset!\n", kobject_name(kobj), kobj,
487 __func__);
488 return -EINVAL;
489 }
490
491 kset = top_kobj->kset;
492 uevent_ops = kset->uevent_ops;
493
494 /* skip the event, if uevent_suppress is set*/
495 if (kobj->uevent_suppress) {
496 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
497 "caused the event to drop!\n",
498 kobject_name(kobj), kobj, __func__);
499 return 0;
500 }
501 /* skip the event, if the filter returns zero. */
502 if (uevent_ops && uevent_ops->filter)
503 if (!uevent_ops->filter(kset, kobj)) {
504 pr_debug("kobject: '%s' (%p): %s: filter function "
505 "caused the event to drop!\n",
506 kobject_name(kobj), kobj, __func__);
507 return 0;
508 }
509
510 /* originating subsystem */
511 if (uevent_ops && uevent_ops->name)
512 subsystem = uevent_ops->name(kset, kobj);
513 else
514 subsystem = kobject_name(&kset->kobj);
515 if (!subsystem) {
516 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
517 "event to drop!\n", kobject_name(kobj), kobj,
518 __func__);
519 return 0;
520 }
521
522 /* environment buffer */
523 env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
524 if (!env)
525 return -ENOMEM;
526
527 /* complete object path */
528 devpath = kobject_get_path(kobj, GFP_KERNEL);
529 if (!devpath) {
530 retval = -ENOENT;
531 goto exit;
532 }
533
534 /* default keys */
535 retval = add_uevent_var(env, "ACTION=%s", action_string);
536 if (retval)
537 goto exit;
538 retval = add_uevent_var(env, "DEVPATH=%s", devpath);
539 if (retval)
540 goto exit;
541 retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
542 if (retval)
543 goto exit;
544
545 /* keys passed in from the caller */
546 if (envp_ext) {
547 for (i = 0; envp_ext[i]; i++) {
548 retval = add_uevent_var(env, "%s", envp_ext[i]);
549 if (retval)
550 goto exit;
551 }
552 }
553
554 /* let the kset specific function add its stuff */
555 if (uevent_ops && uevent_ops->uevent) {
556 retval = uevent_ops->uevent(kset, kobj, env);
557 if (retval) {
558 pr_debug("kobject: '%s' (%p): %s: uevent() returned "
559 "%d\n", kobject_name(kobj), kobj,
560 __func__, retval);
561 goto exit;
562 }
563 }
564
565 switch (action) {
566 case KOBJ_ADD:
567 /*
568 * Mark "add" event so we can make sure we deliver "remove"
569 * event to userspace during automatic cleanup. If
570 * the object did send an "add" event, "remove" will
571 * automatically generated by the core, if not already done
572 * by the caller.
573 */
574 kobj->state_add_uevent_sent = 1;
575 break;
576
577 case KOBJ_UNBIND:
578 zap_modalias_env(env);
579 break;
580
581 default:
582 break;
583 }
584
585 mutex_lock(&uevent_sock_mutex);
586 /* we will send an event, so request a new sequence number */
587 retval = add_uevent_var(env, "SEQNUM=%llu", ++uevent_seqnum);
588 if (retval) {
589 mutex_unlock(&uevent_sock_mutex);
590 goto exit;
591 }
592 retval = kobject_uevent_net_broadcast(kobj, env, action_string,
593 devpath);
594 mutex_unlock(&uevent_sock_mutex);
595
596 #ifdef CONFIG_UEVENT_HELPER
597 /* call uevent_helper, usually only enabled during early boot */
598 if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
599 struct subprocess_info *info;
600
601 retval = add_uevent_var(env, "HOME=/");
602 if (retval)
603 goto exit;
604 retval = add_uevent_var(env,
605 "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
606 if (retval)
607 goto exit;
608 retval = init_uevent_argv(env, subsystem);
609 if (retval)
610 goto exit;
611
612 retval = -ENOMEM;
613 info = call_usermodehelper_setup(env->argv[0], env->argv,
614 env->envp, GFP_KERNEL,
615 NULL, cleanup_uevent_env, env);
616 if (info) {
617 retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
618 env = NULL; /* freed by cleanup_uevent_env */
619 }
620 }
621 #endif
622
623 exit:
624 kfree(devpath);
625 kfree(env);
626 return retval;
627 }
628 EXPORT_SYMBOL_GPL(kobject_uevent_env);
629
630 /**
631 * kobject_uevent - notify userspace by sending an uevent
632 *
633 * @kobj: struct kobject that the action is happening to
634 * @action: action that is happening
635 *
636 * Returns 0 if kobject_uevent() is completed with success or the
637 * corresponding error when it fails.
638 */
kobject_uevent(struct kobject * kobj,enum kobject_action action)639 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
640 {
641 return kobject_uevent_env(kobj, action, NULL);
642 }
643 EXPORT_SYMBOL_GPL(kobject_uevent);
644
645 /**
646 * add_uevent_var - add key value string to the environment buffer
647 * @env: environment buffer structure
648 * @format: printf format for the key=value pair
649 *
650 * Returns 0 if environment variable was added successfully or -ENOMEM
651 * if no space was available.
652 */
add_uevent_var(struct kobj_uevent_env * env,const char * format,...)653 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
654 {
655 va_list args;
656 int len;
657
658 if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
659 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
660 return -ENOMEM;
661 }
662
663 va_start(args, format);
664 len = vsnprintf(&env->buf[env->buflen],
665 sizeof(env->buf) - env->buflen,
666 format, args);
667 va_end(args);
668
669 if (len >= (sizeof(env->buf) - env->buflen)) {
670 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
671 return -ENOMEM;
672 }
673
674 env->envp[env->envp_idx++] = &env->buf[env->buflen];
675 env->buflen += len + 1;
676 return 0;
677 }
678 EXPORT_SYMBOL_GPL(add_uevent_var);
679
680 #if defined(CONFIG_NET)
uevent_net_broadcast(struct sock * usk,struct sk_buff * skb,struct netlink_ext_ack * extack)681 static int uevent_net_broadcast(struct sock *usk, struct sk_buff *skb,
682 struct netlink_ext_ack *extack)
683 {
684 /* u64 to chars: 2^64 - 1 = 21 chars */
685 char buf[sizeof("SEQNUM=") + 21];
686 struct sk_buff *skbc;
687 int ret;
688
689 /* bump and prepare sequence number */
690 ret = snprintf(buf, sizeof(buf), "SEQNUM=%llu", ++uevent_seqnum);
691 if (ret < 0 || (size_t)ret >= sizeof(buf))
692 return -ENOMEM;
693 ret++;
694
695 /* verify message does not overflow */
696 if ((skb->len + ret) > UEVENT_BUFFER_SIZE) {
697 NL_SET_ERR_MSG(extack, "uevent message too big");
698 return -EINVAL;
699 }
700
701 /* copy skb and extend to accommodate sequence number */
702 skbc = skb_copy_expand(skb, 0, ret, GFP_KERNEL);
703 if (!skbc)
704 return -ENOMEM;
705
706 /* append sequence number */
707 skb_put_data(skbc, buf, ret);
708
709 /* remove msg header */
710 skb_pull(skbc, NLMSG_HDRLEN);
711
712 /* set portid 0 to inform userspace message comes from kernel */
713 NETLINK_CB(skbc).portid = 0;
714 NETLINK_CB(skbc).dst_group = 1;
715
716 ret = netlink_broadcast(usk, skbc, 0, 1, GFP_KERNEL);
717 /* ENOBUFS should be handled in userspace */
718 if (ret == -ENOBUFS || ret == -ESRCH)
719 ret = 0;
720
721 return ret;
722 }
723
uevent_net_rcv_skb(struct sk_buff * skb,struct nlmsghdr * nlh,struct netlink_ext_ack * extack)724 static int uevent_net_rcv_skb(struct sk_buff *skb, struct nlmsghdr *nlh,
725 struct netlink_ext_ack *extack)
726 {
727 struct net *net;
728 int ret;
729
730 if (!nlmsg_data(nlh))
731 return -EINVAL;
732
733 /*
734 * Verify that we are allowed to send messages to the target
735 * network namespace. The caller must have CAP_SYS_ADMIN in the
736 * owning user namespace of the target network namespace.
737 */
738 net = sock_net(NETLINK_CB(skb).sk);
739 if (!netlink_ns_capable(skb, net->user_ns, CAP_SYS_ADMIN)) {
740 NL_SET_ERR_MSG(extack, "missing CAP_SYS_ADMIN capability");
741 return -EPERM;
742 }
743
744 mutex_lock(&uevent_sock_mutex);
745 ret = uevent_net_broadcast(net->uevent_sock->sk, skb, extack);
746 mutex_unlock(&uevent_sock_mutex);
747
748 return ret;
749 }
750
uevent_net_rcv(struct sk_buff * skb)751 static void uevent_net_rcv(struct sk_buff *skb)
752 {
753 netlink_rcv_skb(skb, &uevent_net_rcv_skb);
754 }
755
uevent_net_init(struct net * net)756 static int uevent_net_init(struct net *net)
757 {
758 struct uevent_sock *ue_sk;
759 struct netlink_kernel_cfg cfg = {
760 .groups = 1,
761 .input = uevent_net_rcv,
762 .flags = NL_CFG_F_NONROOT_RECV
763 };
764
765 ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
766 if (!ue_sk)
767 return -ENOMEM;
768
769 ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
770 if (!ue_sk->sk) {
771 pr_err("kobject_uevent: unable to create netlink socket!\n");
772 kfree(ue_sk);
773 return -ENODEV;
774 }
775
776 net->uevent_sock = ue_sk;
777
778 /* Restrict uevents to initial user namespace. */
779 if (sock_net(ue_sk->sk)->user_ns == &init_user_ns) {
780 mutex_lock(&uevent_sock_mutex);
781 list_add_tail(&ue_sk->list, &uevent_sock_list);
782 mutex_unlock(&uevent_sock_mutex);
783 }
784
785 return 0;
786 }
787
uevent_net_exit(struct net * net)788 static void uevent_net_exit(struct net *net)
789 {
790 struct uevent_sock *ue_sk = net->uevent_sock;
791
792 if (sock_net(ue_sk->sk)->user_ns == &init_user_ns) {
793 mutex_lock(&uevent_sock_mutex);
794 list_del(&ue_sk->list);
795 mutex_unlock(&uevent_sock_mutex);
796 }
797
798 netlink_kernel_release(ue_sk->sk);
799 kfree(ue_sk);
800 }
801
802 static struct pernet_operations uevent_net_ops = {
803 .init = uevent_net_init,
804 .exit = uevent_net_exit,
805 };
806
kobject_uevent_init(void)807 static int __init kobject_uevent_init(void)
808 {
809 return register_pernet_subsys(&uevent_net_ops);
810 }
811
812
813 postcore_initcall(kobject_uevent_init);
814 #endif
815