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 atomic64_t 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 /* This lock protects uevent_sock_list */
46 static DEFINE_MUTEX(uevent_sock_mutex);
47 #endif
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
kobject_action_type(const char * buf,size_t count,enum kobject_action * type,const char ** args)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
action_arg_word_end(const char * buf,const char * buf_end,char delim)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
kobject_action_args(const char * buf,size_t count,struct kobj_uevent_env ** ret_env)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 */
kobject_synth_uevent(struct kobject * kobj,const char * buf,size_t count)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";
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);
223 out:
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
kobj_usermode_filter(struct kobject * kobj)235 static 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
init_uevent_argv(struct kobj_uevent_env * env,const char * subsystem)251 static 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
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 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
uevent_net_broadcast_tagged(struct sock * usk,struct kobj_uevent_env * env,const char * action_string,const char * devpath)343 static 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
kobject_uevent_net_broadcast(struct kobject * kobj,struct kobj_uevent_env * env,const char * action_string,const char * devpath)382 static 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
zap_modalias_env(struct kobj_uevent_env * env)420 static 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 */
kobject_uevent_env(struct kobject * kobj,enum kobject_action action,char * envp_ext[])473 int 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
638 exit:
639 kfree(devpath);
640 kfree(env);
641 return retval;
642 }
643 EXPORT_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 */
kobject_uevent(struct kobject * kobj,enum kobject_action action)654 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
655 {
656 return kobject_uevent_env(kobj, action, NULL);
657 }
658 EXPORT_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 */
add_uevent_var(struct kobj_uevent_env * env,const char * format,...)668 int 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 }
693 EXPORT_SYMBOL_GPL(add_uevent_var);
694
695 #if defined(CONFIG_NET)
uevent_net_broadcast(struct sock * usk,struct sk_buff * skb,struct netlink_ext_ack * extack)696 static 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
uevent_net_rcv_skb(struct sk_buff * skb,struct nlmsghdr * nlh,struct netlink_ext_ack * extack)740 static 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
uevent_net_rcv(struct sk_buff * skb)765 static void uevent_net_rcv(struct sk_buff *skb)
766 {
767 netlink_rcv_skb(skb, &uevent_net_rcv_skb);
768 }
769
uevent_net_init(struct net * net)770 static 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
uevent_net_exit(struct net * net)802 static 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
816 static struct pernet_operations uevent_net_ops = {
817 .init = uevent_net_init,
818 .exit = uevent_net_exit,
819 };
820
kobject_uevent_init(void)821 static int __init kobject_uevent_init(void)
822 {
823 return register_pernet_subsys(&uevent_net_ops);
824 }
825
826
827 postcore_initcall(kobject_uevent_init);
828 #endif
829