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\n";
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\n";
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 printk(KERN_WARNING "synth uevent: %s: %s",
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 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 len;
254
255 len = strlcpy(&env->buf[env->buflen], subsystem,
256 sizeof(env->buf) - env->buflen);
257 if (len >= (sizeof(env->buf) - env->buflen)) {
258 WARN(1, KERN_ERR "init_uevent_argv: buffer size too small\n");
259 return -ENOMEM;
260 }
261
262 env->argv[0] = uevent_helper;
263 env->argv[1] = &env->buf[env->buflen];
264 env->argv[2] = NULL;
265
266 env->buflen += len + 1;
267 return 0;
268 }
269
cleanup_uevent_env(struct subprocess_info * info)270 static void cleanup_uevent_env(struct subprocess_info *info)
271 {
272 kfree(info->data);
273 }
274 #endif
275
276 #ifdef CONFIG_NET
alloc_uevent_skb(struct kobj_uevent_env * env,const char * action_string,const char * devpath)277 static struct sk_buff *alloc_uevent_skb(struct kobj_uevent_env *env,
278 const char *action_string,
279 const char *devpath)
280 {
281 struct netlink_skb_parms *parms;
282 struct sk_buff *skb = NULL;
283 char *scratch;
284 size_t len;
285
286 /* allocate message with maximum possible size */
287 len = strlen(action_string) + strlen(devpath) + 2;
288 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
289 if (!skb)
290 return NULL;
291
292 /* add header */
293 scratch = skb_put(skb, len);
294 sprintf(scratch, "%s@%s", action_string, devpath);
295
296 skb_put_data(skb, env->buf, env->buflen);
297
298 parms = &NETLINK_CB(skb);
299 parms->creds.uid = GLOBAL_ROOT_UID;
300 parms->creds.gid = GLOBAL_ROOT_GID;
301 parms->dst_group = 1;
302 parms->portid = 0;
303
304 return skb;
305 }
306
uevent_net_broadcast_untagged(struct kobj_uevent_env * env,const char * action_string,const char * devpath)307 static int uevent_net_broadcast_untagged(struct kobj_uevent_env *env,
308 const char *action_string,
309 const char *devpath)
310 {
311 struct sk_buff *skb = NULL;
312 struct uevent_sock *ue_sk;
313 int retval = 0;
314
315 /* send netlink message */
316 list_for_each_entry(ue_sk, &uevent_sock_list, list) {
317 struct sock *uevent_sock = ue_sk->sk;
318
319 if (!netlink_has_listeners(uevent_sock, 1))
320 continue;
321
322 if (!skb) {
323 retval = -ENOMEM;
324 skb = alloc_uevent_skb(env, action_string, devpath);
325 if (!skb)
326 continue;
327 }
328
329 retval = netlink_broadcast(uevent_sock, skb_get(skb), 0, 1,
330 GFP_KERNEL);
331 /* ENOBUFS should be handled in userspace */
332 if (retval == -ENOBUFS || retval == -ESRCH)
333 retval = 0;
334 }
335 consume_skb(skb);
336
337 return retval;
338 }
339
uevent_net_broadcast_tagged(struct sock * usk,struct kobj_uevent_env * env,const char * action_string,const char * devpath)340 static int uevent_net_broadcast_tagged(struct sock *usk,
341 struct kobj_uevent_env *env,
342 const char *action_string,
343 const char *devpath)
344 {
345 struct user_namespace *owning_user_ns = sock_net(usk)->user_ns;
346 struct sk_buff *skb = NULL;
347 int ret = 0;
348
349 skb = alloc_uevent_skb(env, action_string, devpath);
350 if (!skb)
351 return -ENOMEM;
352
353 /* fix credentials */
354 if (owning_user_ns != &init_user_ns) {
355 struct netlink_skb_parms *parms = &NETLINK_CB(skb);
356 kuid_t root_uid;
357 kgid_t root_gid;
358
359 /* fix uid */
360 root_uid = make_kuid(owning_user_ns, 0);
361 if (uid_valid(root_uid))
362 parms->creds.uid = root_uid;
363
364 /* fix gid */
365 root_gid = make_kgid(owning_user_ns, 0);
366 if (gid_valid(root_gid))
367 parms->creds.gid = root_gid;
368 }
369
370 ret = netlink_broadcast(usk, skb, 0, 1, GFP_KERNEL);
371 /* ENOBUFS should be handled in userspace */
372 if (ret == -ENOBUFS || ret == -ESRCH)
373 ret = 0;
374
375 return ret;
376 }
377 #endif
378
kobject_uevent_net_broadcast(struct kobject * kobj,struct kobj_uevent_env * env,const char * action_string,const char * devpath)379 static int kobject_uevent_net_broadcast(struct kobject *kobj,
380 struct kobj_uevent_env *env,
381 const char *action_string,
382 const char *devpath)
383 {
384 int ret = 0;
385
386 #ifdef CONFIG_NET
387 const struct kobj_ns_type_operations *ops;
388 const struct net *net = NULL;
389
390 ops = kobj_ns_ops(kobj);
391 if (!ops && kobj->kset) {
392 struct kobject *ksobj = &kobj->kset->kobj;
393 if (ksobj->parent != NULL)
394 ops = kobj_ns_ops(ksobj->parent);
395 }
396
397 /* kobjects currently only carry network namespace tags and they
398 * are the only tag relevant here since we want to decide which
399 * network namespaces to broadcast the uevent into.
400 */
401 if (ops && ops->netlink_ns && kobj->ktype->namespace)
402 if (ops->type == KOBJ_NS_TYPE_NET)
403 net = kobj->ktype->namespace(kobj);
404
405 if (!net)
406 ret = uevent_net_broadcast_untagged(env, action_string,
407 devpath);
408 else
409 ret = uevent_net_broadcast_tagged(net->uevent_sock->sk, env,
410 action_string, devpath);
411 #endif
412
413 return ret;
414 }
415
zap_modalias_env(struct kobj_uevent_env * env)416 static void zap_modalias_env(struct kobj_uevent_env *env)
417 {
418 static const char modalias_prefix[] = "MODALIAS=";
419 size_t len;
420 int i, j;
421
422 for (i = 0; i < env->envp_idx;) {
423 if (strncmp(env->envp[i], modalias_prefix,
424 sizeof(modalias_prefix) - 1)) {
425 i++;
426 continue;
427 }
428
429 len = strlen(env->envp[i]) + 1;
430
431 if (i != env->envp_idx - 1) {
432 memmove(env->envp[i], env->envp[i + 1],
433 env->buflen - len);
434
435 for (j = i; j < env->envp_idx - 1; j++)
436 env->envp[j] = env->envp[j + 1] - len;
437 }
438
439 env->envp_idx--;
440 env->buflen -= len;
441 }
442 }
443
444 /**
445 * kobject_uevent_env - send an uevent with environmental data
446 *
447 * @kobj: struct kobject that the action is happening to
448 * @action: action that is happening
449 * @envp_ext: pointer to environmental data
450 *
451 * Returns 0 if kobject_uevent_env() is completed with success or the
452 * corresponding error when it fails.
453 */
kobject_uevent_env(struct kobject * kobj,enum kobject_action action,char * envp_ext[])454 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
455 char *envp_ext[])
456 {
457 struct kobj_uevent_env *env;
458 const char *action_string = kobject_actions[action];
459 const char *devpath = NULL;
460 const char *subsystem;
461 struct kobject *top_kobj;
462 struct kset *kset;
463 const struct kset_uevent_ops *uevent_ops;
464 int i = 0;
465 int retval = 0;
466
467 pr_debug("kobject: '%s' (%p): %s\n",
468 kobject_name(kobj), kobj, __func__);
469
470 /* search the kset we belong to */
471 top_kobj = kobj;
472 while (!top_kobj->kset && top_kobj->parent)
473 top_kobj = top_kobj->parent;
474
475 if (!top_kobj->kset) {
476 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
477 "without kset!\n", kobject_name(kobj), kobj,
478 __func__);
479 return -EINVAL;
480 }
481
482 kset = top_kobj->kset;
483 uevent_ops = kset->uevent_ops;
484
485 /* skip the event, if uevent_suppress is set*/
486 if (kobj->uevent_suppress) {
487 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
488 "caused the event to drop!\n",
489 kobject_name(kobj), kobj, __func__);
490 return 0;
491 }
492 /* skip the event, if the filter returns zero. */
493 if (uevent_ops && uevent_ops->filter)
494 if (!uevent_ops->filter(kset, kobj)) {
495 pr_debug("kobject: '%s' (%p): %s: filter function "
496 "caused the event to drop!\n",
497 kobject_name(kobj), kobj, __func__);
498 return 0;
499 }
500
501 /* originating subsystem */
502 if (uevent_ops && uevent_ops->name)
503 subsystem = uevent_ops->name(kset, kobj);
504 else
505 subsystem = kobject_name(&kset->kobj);
506 if (!subsystem) {
507 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
508 "event to drop!\n", kobject_name(kobj), kobj,
509 __func__);
510 return 0;
511 }
512
513 /* environment buffer */
514 env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
515 if (!env)
516 return -ENOMEM;
517
518 /* complete object path */
519 devpath = kobject_get_path(kobj, GFP_KERNEL);
520 if (!devpath) {
521 retval = -ENOENT;
522 goto exit;
523 }
524
525 /* default keys */
526 retval = add_uevent_var(env, "ACTION=%s", action_string);
527 if (retval)
528 goto exit;
529 retval = add_uevent_var(env, "DEVPATH=%s", devpath);
530 if (retval)
531 goto exit;
532 retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
533 if (retval)
534 goto exit;
535
536 /* keys passed in from the caller */
537 if (envp_ext) {
538 for (i = 0; envp_ext[i]; i++) {
539 retval = add_uevent_var(env, "%s", envp_ext[i]);
540 if (retval)
541 goto exit;
542 }
543 }
544
545 /* let the kset specific function add its stuff */
546 if (uevent_ops && uevent_ops->uevent) {
547 retval = uevent_ops->uevent(kset, kobj, env);
548 if (retval) {
549 pr_debug("kobject: '%s' (%p): %s: uevent() returned "
550 "%d\n", kobject_name(kobj), kobj,
551 __func__, retval);
552 goto exit;
553 }
554 }
555
556 switch (action) {
557 case KOBJ_ADD:
558 /*
559 * Mark "add" event so we can make sure we deliver "remove"
560 * event to userspace during automatic cleanup. If
561 * the object did send an "add" event, "remove" will
562 * automatically generated by the core, if not already done
563 * by the caller.
564 */
565 kobj->state_add_uevent_sent = 1;
566 break;
567
568 case KOBJ_REMOVE:
569 kobj->state_remove_uevent_sent = 1;
570 break;
571
572 case KOBJ_UNBIND:
573 zap_modalias_env(env);
574 break;
575
576 default:
577 break;
578 }
579
580 mutex_lock(&uevent_sock_mutex);
581 /* we will send an event, so request a new sequence number */
582 retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum);
583 if (retval) {
584 mutex_unlock(&uevent_sock_mutex);
585 goto exit;
586 }
587 retval = kobject_uevent_net_broadcast(kobj, env, action_string,
588 devpath);
589 mutex_unlock(&uevent_sock_mutex);
590
591 #ifdef CONFIG_UEVENT_HELPER
592 /* call uevent_helper, usually only enabled during early boot */
593 if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
594 struct subprocess_info *info;
595
596 retval = add_uevent_var(env, "HOME=/");
597 if (retval)
598 goto exit;
599 retval = add_uevent_var(env,
600 "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
601 if (retval)
602 goto exit;
603 retval = init_uevent_argv(env, subsystem);
604 if (retval)
605 goto exit;
606
607 retval = -ENOMEM;
608 info = call_usermodehelper_setup(env->argv[0], env->argv,
609 env->envp, GFP_KERNEL,
610 NULL, cleanup_uevent_env, env);
611 if (info) {
612 retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
613 env = NULL; /* freed by cleanup_uevent_env */
614 }
615 }
616 #endif
617
618 exit:
619 kfree(devpath);
620 kfree(env);
621 return retval;
622 }
623 EXPORT_SYMBOL_GPL(kobject_uevent_env);
624
625 /**
626 * kobject_uevent - notify userspace by sending an uevent
627 *
628 * @kobj: struct kobject that the action is happening to
629 * @action: action that is happening
630 *
631 * Returns 0 if kobject_uevent() is completed with success or the
632 * corresponding error when it fails.
633 */
kobject_uevent(struct kobject * kobj,enum kobject_action action)634 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
635 {
636 return kobject_uevent_env(kobj, action, NULL);
637 }
638 EXPORT_SYMBOL_GPL(kobject_uevent);
639
640 /**
641 * add_uevent_var - add key value string to the environment buffer
642 * @env: environment buffer structure
643 * @format: printf format for the key=value pair
644 *
645 * Returns 0 if environment variable was added successfully or -ENOMEM
646 * if no space was available.
647 */
add_uevent_var(struct kobj_uevent_env * env,const char * format,...)648 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
649 {
650 va_list args;
651 int len;
652
653 if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
654 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
655 return -ENOMEM;
656 }
657
658 va_start(args, format);
659 len = vsnprintf(&env->buf[env->buflen],
660 sizeof(env->buf) - env->buflen,
661 format, args);
662 va_end(args);
663
664 if (len >= (sizeof(env->buf) - env->buflen)) {
665 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
666 return -ENOMEM;
667 }
668
669 env->envp[env->envp_idx++] = &env->buf[env->buflen];
670 env->buflen += len + 1;
671 return 0;
672 }
673 EXPORT_SYMBOL_GPL(add_uevent_var);
674
675 #if defined(CONFIG_NET)
uevent_net_broadcast(struct sock * usk,struct sk_buff * skb,struct netlink_ext_ack * extack)676 static int uevent_net_broadcast(struct sock *usk, struct sk_buff *skb,
677 struct netlink_ext_ack *extack)
678 {
679 /* u64 to chars: 2^64 - 1 = 21 chars */
680 char buf[sizeof("SEQNUM=") + 21];
681 struct sk_buff *skbc;
682 int ret;
683
684 /* bump and prepare sequence number */
685 ret = snprintf(buf, sizeof(buf), "SEQNUM=%llu", ++uevent_seqnum);
686 if (ret < 0 || (size_t)ret >= sizeof(buf))
687 return -ENOMEM;
688 ret++;
689
690 /* verify message does not overflow */
691 if ((skb->len + ret) > UEVENT_BUFFER_SIZE) {
692 NL_SET_ERR_MSG(extack, "uevent message too big");
693 return -EINVAL;
694 }
695
696 /* copy skb and extend to accommodate sequence number */
697 skbc = skb_copy_expand(skb, 0, ret, GFP_KERNEL);
698 if (!skbc)
699 return -ENOMEM;
700
701 /* append sequence number */
702 skb_put_data(skbc, buf, ret);
703
704 /* remove msg header */
705 skb_pull(skbc, NLMSG_HDRLEN);
706
707 /* set portid 0 to inform userspace message comes from kernel */
708 NETLINK_CB(skbc).portid = 0;
709 NETLINK_CB(skbc).dst_group = 1;
710
711 ret = netlink_broadcast(usk, skbc, 0, 1, GFP_KERNEL);
712 /* ENOBUFS should be handled in userspace */
713 if (ret == -ENOBUFS || ret == -ESRCH)
714 ret = 0;
715
716 return ret;
717 }
718
uevent_net_rcv_skb(struct sk_buff * skb,struct nlmsghdr * nlh,struct netlink_ext_ack * extack)719 static int uevent_net_rcv_skb(struct sk_buff *skb, struct nlmsghdr *nlh,
720 struct netlink_ext_ack *extack)
721 {
722 struct net *net;
723 int ret;
724
725 if (!nlmsg_data(nlh))
726 return -EINVAL;
727
728 /*
729 * Verify that we are allowed to send messages to the target
730 * network namespace. The caller must have CAP_SYS_ADMIN in the
731 * owning user namespace of the target network namespace.
732 */
733 net = sock_net(NETLINK_CB(skb).sk);
734 if (!netlink_ns_capable(skb, net->user_ns, CAP_SYS_ADMIN)) {
735 NL_SET_ERR_MSG(extack, "missing CAP_SYS_ADMIN capability");
736 return -EPERM;
737 }
738
739 mutex_lock(&uevent_sock_mutex);
740 ret = uevent_net_broadcast(net->uevent_sock->sk, skb, extack);
741 mutex_unlock(&uevent_sock_mutex);
742
743 return ret;
744 }
745
uevent_net_rcv(struct sk_buff * skb)746 static void uevent_net_rcv(struct sk_buff *skb)
747 {
748 netlink_rcv_skb(skb, &uevent_net_rcv_skb);
749 }
750
uevent_net_init(struct net * net)751 static int uevent_net_init(struct net *net)
752 {
753 struct uevent_sock *ue_sk;
754 struct netlink_kernel_cfg cfg = {
755 .groups = 1,
756 .input = uevent_net_rcv,
757 .flags = NL_CFG_F_NONROOT_RECV
758 };
759
760 ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
761 if (!ue_sk)
762 return -ENOMEM;
763
764 ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
765 if (!ue_sk->sk) {
766 printk(KERN_ERR
767 "kobject_uevent: unable to create netlink socket!\n");
768 kfree(ue_sk);
769 return -ENODEV;
770 }
771
772 net->uevent_sock = ue_sk;
773
774 /* Restrict uevents to initial user namespace. */
775 if (sock_net(ue_sk->sk)->user_ns == &init_user_ns) {
776 mutex_lock(&uevent_sock_mutex);
777 list_add_tail(&ue_sk->list, &uevent_sock_list);
778 mutex_unlock(&uevent_sock_mutex);
779 }
780
781 return 0;
782 }
783
uevent_net_exit(struct net * net)784 static void uevent_net_exit(struct net *net)
785 {
786 struct uevent_sock *ue_sk = net->uevent_sock;
787
788 if (sock_net(ue_sk->sk)->user_ns == &init_user_ns) {
789 mutex_lock(&uevent_sock_mutex);
790 list_del(&ue_sk->list);
791 mutex_unlock(&uevent_sock_mutex);
792 }
793
794 netlink_kernel_release(ue_sk->sk);
795 kfree(ue_sk);
796 }
797
798 static struct pernet_operations uevent_net_ops = {
799 .init = uevent_net_init,
800 .exit = uevent_net_exit,
801 };
802
kobject_uevent_init(void)803 static int __init kobject_uevent_init(void)
804 {
805 return register_pernet_subsys(&uevent_net_ops);
806 }
807
808
809 postcore_initcall(kobject_uevent_init);
810 #endif
811
