1 // SPDX-License-Identifier: GPL-2.0
3 * kernel userspace event delivery
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.
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>
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>
29 #include <net/netlink.h>
30 #include <net/net_namespace.h>
34 #ifdef CONFIG_UEVENT_HELPER
35 char uevent_helper
[UEVENT_HELPER_PATH_LEN
] = CONFIG_UEVENT_HELPER_PATH
;
39 struct list_head list
;
44 static LIST_HEAD(uevent_sock_list
);
47 /* This lock protects uevent_seqnum and uevent_sock_list */
48 static DEFINE_MUTEX(uevent_sock_mutex
);
50 /* the strings here must match the enum in include/linux/kobject.h */
51 static const char *kobject_actions
[] = {
53 [KOBJ_REMOVE
] = "remove",
54 [KOBJ_CHANGE
] = "change",
56 [KOBJ_ONLINE
] = "online",
57 [KOBJ_OFFLINE
] = "offline",
59 [KOBJ_UNBIND
] = "unbind",
62 static int kobject_action_type(const char *buf
, size_t count
,
63 enum kobject_action
*type
,
66 enum kobject_action action
;
68 const char *args_start
;
71 if (count
&& (buf
[count
-1] == '\n' || buf
[count
-1] == '\0'))
77 args_start
= strnchr(buf
, count
, ' ');
79 count_first
= args_start
- buf
;
80 args_start
= args_start
+ 1;
84 for (action
= 0; action
< ARRAY_SIZE(kobject_actions
); action
++) {
85 if (strncmp(kobject_actions
[action
], buf
, count_first
) != 0)
87 if (kobject_actions
[action
][count_first
] != '\0')
99 static const char *action_arg_word_end(const char *buf
, const char *buf_end
,
102 const char *next
= buf
;
104 while (next
<= buf_end
&& *next
!= delim
)
105 if (!isalnum(*next
++))
114 static int kobject_action_args(const char *buf
, size_t count
,
115 struct kobj_uevent_env
**ret_env
)
117 struct kobj_uevent_env
*env
= NULL
;
118 const char *next
, *buf_end
, *key
;
122 if (count
&& (buf
[count
- 1] == '\n' || buf
[count
- 1] == '\0'))
128 env
= kzalloc(sizeof(*env
), GFP_KERNEL
);
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
))
138 * the rest are custom environment variables in KEY=VALUE
139 * format with ' ' delimiter between each KEY=VALUE pair
141 next
= buf
+ UUID_STRING_LEN
;
142 buf_end
= buf
+ count
- 1;
144 while (next
<= buf_end
) {
148 /* skip the ' ', key must follow */
154 next
= action_arg_word_end(buf
, buf_end
, '=');
155 if (!next
|| next
> buf_end
|| *next
!= '=')
157 key_len
= next
- buf
;
159 /* skip the '=', value must follow */
160 if (++next
> buf_end
)
164 next
= action_arg_word_end(buf
, buf_end
, ' ');
168 if (add_uevent_var(env
, "SYNTH_ARG_%.*s=%.*s",
169 key_len
, key
, (int) (next
- buf
), buf
))
183 * kobject_synth_uevent - send synthetic uevent with arguments
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
189 * Returns 0 if kobject_synthetic_uevent() is completed with success or the
190 * corresponding error when it fails.
192 int kobject_synth_uevent(struct kobject
*kobj
, const char *buf
, size_t count
)
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
;
201 r
= kobject_action_type(buf
, count
, &action
, &action_args
);
203 msg
= "unknown uevent action string";
208 r
= kobject_uevent_env(kobj
, action
, no_uuid_envp
);
212 r
= kobject_action_args(action_args
,
213 count
- (action_args
- buf
), &env
);
215 msg
= "incorrect uevent action arguments";
222 r
= kobject_uevent_env(kobj
, action
, env
->envp
);
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");
235 #ifdef CONFIG_UEVENT_HELPER
236 static int kobj_usermode_filter(struct kobject
*kobj
)
238 const struct kobj_ns_type_operations
*ops
;
240 ops
= kobj_ns_ops(kobj
);
242 const void *init_ns
, *ns
;
244 ns
= kobj
->ktype
->namespace(kobj
);
245 init_ns
= ops
->initial_ns();
246 return ns
!= init_ns
;
252 static int init_uevent_argv(struct kobj_uevent_env
*env
, const char *subsystem
)
254 int buffer_size
= sizeof(env
->buf
) - env
->buflen
;
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",
264 env
->argv
[0] = uevent_helper
;
265 env
->argv
[1] = &env
->buf
[env
->buflen
];
268 env
->buflen
+= len
+ 1;
272 static void cleanup_uevent_env(struct subprocess_info
*info
)
279 static struct sk_buff
*alloc_uevent_skb(struct kobj_uevent_env
*env
,
280 const char *action_string
,
283 struct netlink_skb_parms
*parms
;
284 struct sk_buff
*skb
= NULL
;
288 /* allocate message with maximum possible size */
289 len
= strlen(action_string
) + strlen(devpath
) + 2;
290 skb
= alloc_skb(len
+ env
->buflen
, GFP_KERNEL
);
295 scratch
= skb_put(skb
, len
);
296 sprintf(scratch
, "%s@%s", action_string
, devpath
);
298 skb_put_data(skb
, env
->buf
, env
->buflen
);
300 parms
= &NETLINK_CB(skb
);
301 parms
->creds
.uid
= GLOBAL_ROOT_UID
;
302 parms
->creds
.gid
= GLOBAL_ROOT_GID
;
303 parms
->dst_group
= 1;
309 static int uevent_net_broadcast_untagged(struct kobj_uevent_env
*env
,
310 const char *action_string
,
313 struct sk_buff
*skb
= NULL
;
314 struct uevent_sock
*ue_sk
;
317 /* send netlink message */
318 list_for_each_entry(ue_sk
, &uevent_sock_list
, list
) {
319 struct sock
*uevent_sock
= ue_sk
->sk
;
321 if (!netlink_has_listeners(uevent_sock
, 1))
326 skb
= alloc_uevent_skb(env
, action_string
, devpath
);
331 retval
= netlink_broadcast(uevent_sock
, skb_get(skb
), 0, 1,
333 /* ENOBUFS should be handled in userspace */
334 if (retval
== -ENOBUFS
|| retval
== -ESRCH
)
342 static int uevent_net_broadcast_tagged(struct sock
*usk
,
343 struct kobj_uevent_env
*env
,
344 const char *action_string
,
347 struct user_namespace
*owning_user_ns
= sock_net(usk
)->user_ns
;
348 struct sk_buff
*skb
= NULL
;
351 skb
= alloc_uevent_skb(env
, action_string
, devpath
);
355 /* fix credentials */
356 if (owning_user_ns
!= &init_user_ns
) {
357 struct netlink_skb_parms
*parms
= &NETLINK_CB(skb
);
362 root_uid
= make_kuid(owning_user_ns
, 0);
363 if (uid_valid(root_uid
))
364 parms
->creds
.uid
= root_uid
;
367 root_gid
= make_kgid(owning_user_ns
, 0);
368 if (gid_valid(root_gid
))
369 parms
->creds
.gid
= root_gid
;
372 ret
= netlink_broadcast(usk
, skb
, 0, 1, GFP_KERNEL
);
373 /* ENOBUFS should be handled in userspace */
374 if (ret
== -ENOBUFS
|| ret
== -ESRCH
)
381 static int kobject_uevent_net_broadcast(struct kobject
*kobj
,
382 struct kobj_uevent_env
*env
,
383 const char *action_string
,
389 const struct kobj_ns_type_operations
*ops
;
390 const struct net
*net
= NULL
;
392 ops
= kobj_ns_ops(kobj
);
393 if (!ops
&& kobj
->kset
) {
394 struct kobject
*ksobj
= &kobj
->kset
->kobj
;
396 if (ksobj
->parent
!= NULL
)
397 ops
= kobj_ns_ops(ksobj
->parent
);
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.
404 if (ops
&& ops
->netlink_ns
&& kobj
->ktype
->namespace)
405 if (ops
->type
== KOBJ_NS_TYPE_NET
)
406 net
= kobj
->ktype
->namespace(kobj
);
409 ret
= uevent_net_broadcast_untagged(env
, action_string
,
412 ret
= uevent_net_broadcast_tagged(net
->uevent_sock
->sk
, env
,
413 action_string
, devpath
);
419 static void zap_modalias_env(struct kobj_uevent_env
*env
)
421 static const char modalias_prefix
[] = "MODALIAS=";
425 for (i
= 0; i
< env
->envp_idx
;) {
426 if (strncmp(env
->envp
[i
], modalias_prefix
,
427 sizeof(modalias_prefix
) - 1)) {
432 len
= strlen(env
->envp
[i
]) + 1;
434 if (i
!= env
->envp_idx
- 1) {
435 memmove(env
->envp
[i
], env
->envp
[i
+ 1],
438 for (j
= i
; j
< env
->envp_idx
- 1; j
++)
439 env
->envp
[j
] = env
->envp
[j
+ 1] - len
;
448 * kobject_uevent_env - send an uevent with environmental data
450 * @kobj: struct kobject that the action is happening to
451 * @action: action that is happening
452 * @envp_ext: pointer to environmental data
454 * Returns 0 if kobject_uevent_env() is completed with success or the
455 * corresponding error when it fails.
457 int kobject_uevent_env(struct kobject
*kobj
, enum kobject_action action
,
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
;
466 const struct kset_uevent_ops
*uevent_ops
;
471 * Mark "remove" event done regardless of result, for some subsystems
472 * do not want to re-trigger "remove" event via automatic cleanup.
474 if (action
== KOBJ_REMOVE
)
475 kobj
->state_remove_uevent_sent
= 1;
477 pr_debug("kobject: '%s' (%p): %s\n",
478 kobject_name(kobj
), kobj
, __func__
);
480 /* search the kset we belong to */
482 while (!top_kobj
->kset
&& top_kobj
->parent
)
483 top_kobj
= top_kobj
->parent
;
485 if (!top_kobj
->kset
) {
486 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
487 "without kset!\n", kobject_name(kobj
), kobj
,
492 kset
= top_kobj
->kset
;
493 uevent_ops
= kset
->uevent_ops
;
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__
);
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__
);
511 /* originating subsystem */
512 if (uevent_ops
&& uevent_ops
->name
)
513 subsystem
= uevent_ops
->name(kset
, kobj
);
515 subsystem
= kobject_name(&kset
->kobj
);
517 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
518 "event to drop!\n", kobject_name(kobj
), kobj
,
523 /* environment buffer */
524 env
= kzalloc(sizeof(struct kobj_uevent_env
), GFP_KERNEL
);
528 /* complete object path */
529 devpath
= kobject_get_path(kobj
, GFP_KERNEL
);
536 retval
= add_uevent_var(env
, "ACTION=%s", action_string
);
539 retval
= add_uevent_var(env
, "DEVPATH=%s", devpath
);
542 retval
= add_uevent_var(env
, "SUBSYSTEM=%s", subsystem
);
546 /* keys passed in from the caller */
548 for (i
= 0; envp_ext
[i
]; i
++) {
549 retval
= add_uevent_var(env
, "%s", envp_ext
[i
]);
555 /* let the kset specific function add its stuff */
556 if (uevent_ops
&& uevent_ops
->uevent
) {
557 retval
= uevent_ops
->uevent(kset
, kobj
, env
);
559 pr_debug("kobject: '%s' (%p): %s: uevent() returned "
560 "%d\n", kobject_name(kobj
), kobj
,
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
575 kobj
->state_add_uevent_sent
= 1;
579 zap_modalias_env(env
);
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
);
590 mutex_unlock(&uevent_sock_mutex
);
593 retval
= kobject_uevent_net_broadcast(kobj
, env
, action_string
,
595 mutex_unlock(&uevent_sock_mutex
);
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
;
602 retval
= add_uevent_var(env
, "HOME=/");
605 retval
= add_uevent_var(env
,
606 "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
609 retval
= init_uevent_argv(env
, subsystem
);
614 info
= call_usermodehelper_setup(env
->argv
[0], env
->argv
,
615 env
->envp
, GFP_KERNEL
,
616 NULL
, cleanup_uevent_env
, env
);
618 retval
= call_usermodehelper_exec(info
, UMH_NO_WAIT
);
619 env
= NULL
; /* freed by cleanup_uevent_env */
629 EXPORT_SYMBOL_GPL(kobject_uevent_env
);
632 * kobject_uevent - notify userspace by sending an uevent
634 * @kobj: struct kobject that the action is happening to
635 * @action: action that is happening
637 * Returns 0 if kobject_uevent() is completed with success or the
638 * corresponding error when it fails.
640 int kobject_uevent(struct kobject
*kobj
, enum kobject_action action
)
642 return kobject_uevent_env(kobj
, action
, NULL
);
644 EXPORT_SYMBOL_GPL(kobject_uevent
);
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
651 * Returns 0 if environment variable was added successfully or -ENOMEM
652 * if no space was available.
654 int add_uevent_var(struct kobj_uevent_env
*env
, const char *format
, ...)
659 if (env
->envp_idx
>= ARRAY_SIZE(env
->envp
)) {
660 WARN(1, KERN_ERR
"add_uevent_var: too many keys\n");
664 va_start(args
, format
);
665 len
= vsnprintf(&env
->buf
[env
->buflen
],
666 sizeof(env
->buf
) - env
->buflen
,
670 if (len
>= (sizeof(env
->buf
) - env
->buflen
)) {
671 WARN(1, KERN_ERR
"add_uevent_var: buffer size too small\n");
675 env
->envp
[env
->envp_idx
++] = &env
->buf
[env
->buflen
];
676 env
->buflen
+= len
+ 1;
679 EXPORT_SYMBOL_GPL(add_uevent_var
);
681 #if defined(CONFIG_NET)
682 static int uevent_net_broadcast(struct sock
*usk
, struct sk_buff
*skb
,
683 struct netlink_ext_ack
*extack
)
685 /* u64 to chars: 2^64 - 1 = 21 chars */
686 char buf
[sizeof("SEQNUM=") + 21];
687 struct sk_buff
*skbc
;
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
))
696 /* verify message does not overflow */
697 if ((skb
->len
+ ret
) > UEVENT_BUFFER_SIZE
) {
698 NL_SET_ERR_MSG(extack
, "uevent message too big");
702 /* copy skb and extend to accommodate sequence number */
703 skbc
= skb_copy_expand(skb
, 0, ret
, GFP_KERNEL
);
707 /* append sequence number */
708 skb_put_data(skbc
, buf
, ret
);
710 /* remove msg header */
711 skb_pull(skbc
, NLMSG_HDRLEN
);
713 /* set portid 0 to inform userspace message comes from kernel */
714 NETLINK_CB(skbc
).portid
= 0;
715 NETLINK_CB(skbc
).dst_group
= 1;
717 ret
= netlink_broadcast(usk
, skbc
, 0, 1, GFP_KERNEL
);
718 /* ENOBUFS should be handled in userspace */
719 if (ret
== -ENOBUFS
|| ret
== -ESRCH
)
725 static int uevent_net_rcv_skb(struct sk_buff
*skb
, struct nlmsghdr
*nlh
,
726 struct netlink_ext_ack
*extack
)
731 if (!nlmsg_data(nlh
))
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.
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");
745 mutex_lock(&uevent_sock_mutex
);
746 ret
= uevent_net_broadcast(net
->uevent_sock
->sk
, skb
, extack
);
747 mutex_unlock(&uevent_sock_mutex
);
752 static void uevent_net_rcv(struct sk_buff
*skb
)
754 netlink_rcv_skb(skb
, &uevent_net_rcv_skb
);
757 static int uevent_net_init(struct net
*net
)
759 struct uevent_sock
*ue_sk
;
760 struct netlink_kernel_cfg cfg
= {
762 .input
= uevent_net_rcv
,
763 .flags
= NL_CFG_F_NONROOT_RECV
766 ue_sk
= kzalloc(sizeof(*ue_sk
), GFP_KERNEL
);
770 ue_sk
->sk
= netlink_kernel_create(net
, NETLINK_KOBJECT_UEVENT
, &cfg
);
772 pr_err("kobject_uevent: unable to create netlink socket!\n");
777 net
->uevent_sock
= ue_sk
;
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
);
789 static void uevent_net_exit(struct net
*net
)
791 struct uevent_sock
*ue_sk
= net
->uevent_sock
;
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
);
799 netlink_kernel_release(ue_sk
->sk
);
803 static struct pernet_operations uevent_net_ops
= {
804 .init
= uevent_net_init
,
805 .exit
= uevent_net_exit
,
808 static int __init
kobject_uevent_init(void)
810 return register_pernet_subsys(&uevent_net_ops
);
814 postcore_initcall(kobject_uevent_init
);