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1 | /* | |
2 | * kernel userspace event delivery | |
3 | * | |
4 | * Copyright (C) 2004 Red Hat, Inc. All rights reserved. | |
5 | * Copyright (C) 2004 Novell, Inc. All rights reserved. | |
6 | * Copyright (C) 2004 IBM, Inc. All rights reserved. | |
7 | * | |
8 | * Licensed under the GNU GPL v2. | |
9 | * | |
10 | * Authors: | |
11 | * Robert Love <rml@novell.com> | |
12 | * Kay Sievers <kay.sievers@vrfy.org> | |
13 | * Arjan van de Ven <arjanv@redhat.com> | |
14 | * Greg Kroah-Hartman <greg@kroah.com> | |
15 | */ | |
16 | ||
17 | #include <linux/spinlock.h> | |
18 | #include <linux/string.h> | |
19 | #include <linux/kobject.h> | |
20 | #include <linux/export.h> | |
21 | #include <linux/kmod.h> | |
22 | #include <linux/slab.h> | |
23 | #include <linux/user_namespace.h> | |
24 | #include <linux/socket.h> | |
25 | #include <linux/skbuff.h> | |
26 | #include <linux/netlink.h> | |
27 | #include <net/sock.h> | |
28 | #include <net/net_namespace.h> | |
29 | ||
30 | ||
31 | u64 uevent_seqnum; | |
32 | char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH; | |
33 | #ifdef CONFIG_NET | |
34 | struct uevent_sock { | |
35 | struct list_head list; | |
36 | struct sock *sk; | |
37 | }; | |
38 | static LIST_HEAD(uevent_sock_list); | |
39 | #endif | |
40 | ||
41 | /* This lock protects uevent_seqnum and uevent_sock_list */ | |
42 | static DEFINE_MUTEX(uevent_sock_mutex); | |
43 | ||
44 | /* the strings here must match the enum in include/linux/kobject.h */ | |
45 | static const char *kobject_actions[] = { | |
46 | [KOBJ_ADD] = "add", | |
47 | [KOBJ_REMOVE] = "remove", | |
48 | [KOBJ_CHANGE] = "change", | |
49 | [KOBJ_MOVE] = "move", | |
50 | [KOBJ_ONLINE] = "online", | |
51 | [KOBJ_OFFLINE] = "offline", | |
52 | }; | |
53 | ||
54 | /** | |
55 | * kobject_action_type - translate action string to numeric type | |
56 | * | |
57 | * @buf: buffer containing the action string, newline is ignored | |
58 | * @len: length of buffer | |
59 | * @type: pointer to the location to store the action type | |
60 | * | |
61 | * Returns 0 if the action string was recognized. | |
62 | */ | |
63 | int kobject_action_type(const char *buf, size_t count, | |
64 | enum kobject_action *type) | |
65 | { | |
66 | enum kobject_action action; | |
67 | int ret = -EINVAL; | |
68 | ||
69 | if (count && (buf[count-1] == '\n' || buf[count-1] == '\0')) | |
70 | count--; | |
71 | ||
72 | if (!count) | |
73 | goto out; | |
74 | ||
75 | for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) { | |
76 | if (strncmp(kobject_actions[action], buf, count) != 0) | |
77 | continue; | |
78 | if (kobject_actions[action][count] != '\0') | |
79 | continue; | |
80 | *type = action; | |
81 | ret = 0; | |
82 | break; | |
83 | } | |
84 | out: | |
85 | return ret; | |
86 | } | |
87 | ||
88 | #ifdef CONFIG_NET | |
89 | static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data) | |
90 | { | |
91 | struct kobject *kobj = data, *ksobj; | |
92 | const struct kobj_ns_type_operations *ops; | |
93 | ||
94 | ops = kobj_ns_ops(kobj); | |
95 | if (!ops && kobj->kset) { | |
96 | ksobj = &kobj->kset->kobj; | |
97 | if (ksobj->parent != NULL) | |
98 | ops = kobj_ns_ops(ksobj->parent); | |
99 | } | |
100 | ||
101 | if (ops && ops->netlink_ns && kobj->ktype->namespace) { | |
102 | const void *sock_ns, *ns; | |
103 | ns = kobj->ktype->namespace(kobj); | |
104 | sock_ns = ops->netlink_ns(dsk); | |
105 | return sock_ns != ns; | |
106 | } | |
107 | ||
108 | return 0; | |
109 | } | |
110 | #endif | |
111 | ||
112 | static int kobj_usermode_filter(struct kobject *kobj) | |
113 | { | |
114 | const struct kobj_ns_type_operations *ops; | |
115 | ||
116 | ops = kobj_ns_ops(kobj); | |
117 | if (ops) { | |
118 | const void *init_ns, *ns; | |
119 | ns = kobj->ktype->namespace(kobj); | |
120 | init_ns = ops->initial_ns(); | |
121 | return ns != init_ns; | |
122 | } | |
123 | ||
124 | return 0; | |
125 | } | |
126 | ||
127 | /** | |
128 | * kobject_uevent_env - send an uevent with environmental data | |
129 | * | |
130 | * @action: action that is happening | |
131 | * @kobj: struct kobject that the action is happening to | |
132 | * @envp_ext: pointer to environmental data | |
133 | * | |
134 | * Returns 0 if kobject_uevent_env() is completed with success or the | |
135 | * corresponding error when it fails. | |
136 | */ | |
137 | int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, | |
138 | char *envp_ext[]) | |
139 | { | |
140 | struct kobj_uevent_env *env; | |
141 | const char *action_string = kobject_actions[action]; | |
142 | const char *devpath = NULL; | |
143 | const char *subsystem; | |
144 | struct kobject *top_kobj; | |
145 | struct kset *kset; | |
146 | const struct kset_uevent_ops *uevent_ops; | |
147 | int i = 0; | |
148 | int retval = 0; | |
149 | #ifdef CONFIG_NET | |
150 | struct uevent_sock *ue_sk; | |
151 | #endif | |
152 | ||
153 | pr_debug("kobject: '%s' (%p): %s\n", | |
154 | kobject_name(kobj), kobj, __func__); | |
155 | ||
156 | /* search the kset we belong to */ | |
157 | top_kobj = kobj; | |
158 | while (!top_kobj->kset && top_kobj->parent) | |
159 | top_kobj = top_kobj->parent; | |
160 | ||
161 | if (!top_kobj->kset) { | |
162 | pr_debug("kobject: '%s' (%p): %s: attempted to send uevent " | |
163 | "without kset!\n", kobject_name(kobj), kobj, | |
164 | __func__); | |
165 | return -EINVAL; | |
166 | } | |
167 | ||
168 | kset = top_kobj->kset; | |
169 | uevent_ops = kset->uevent_ops; | |
170 | ||
171 | /* skip the event, if uevent_suppress is set*/ | |
172 | if (kobj->uevent_suppress) { | |
173 | pr_debug("kobject: '%s' (%p): %s: uevent_suppress " | |
174 | "caused the event to drop!\n", | |
175 | kobject_name(kobj), kobj, __func__); | |
176 | return 0; | |
177 | } | |
178 | /* skip the event, if the filter returns zero. */ | |
179 | if (uevent_ops && uevent_ops->filter) | |
180 | if (!uevent_ops->filter(kset, kobj)) { | |
181 | pr_debug("kobject: '%s' (%p): %s: filter function " | |
182 | "caused the event to drop!\n", | |
183 | kobject_name(kobj), kobj, __func__); | |
184 | return 0; | |
185 | } | |
186 | ||
187 | /* originating subsystem */ | |
188 | if (uevent_ops && uevent_ops->name) | |
189 | subsystem = uevent_ops->name(kset, kobj); | |
190 | else | |
191 | subsystem = kobject_name(&kset->kobj); | |
192 | if (!subsystem) { | |
193 | pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the " | |
194 | "event to drop!\n", kobject_name(kobj), kobj, | |
195 | __func__); | |
196 | return 0; | |
197 | } | |
198 | ||
199 | /* environment buffer */ | |
200 | env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL); | |
201 | if (!env) | |
202 | return -ENOMEM; | |
203 | ||
204 | /* complete object path */ | |
205 | devpath = kobject_get_path(kobj, GFP_KERNEL); | |
206 | if (!devpath) { | |
207 | retval = -ENOENT; | |
208 | goto exit; | |
209 | } | |
210 | ||
211 | /* default keys */ | |
212 | retval = add_uevent_var(env, "ACTION=%s", action_string); | |
213 | if (retval) | |
214 | goto exit; | |
215 | retval = add_uevent_var(env, "DEVPATH=%s", devpath); | |
216 | if (retval) | |
217 | goto exit; | |
218 | retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem); | |
219 | if (retval) | |
220 | goto exit; | |
221 | ||
222 | /* keys passed in from the caller */ | |
223 | if (envp_ext) { | |
224 | for (i = 0; envp_ext[i]; i++) { | |
225 | retval = add_uevent_var(env, "%s", envp_ext[i]); | |
226 | if (retval) | |
227 | goto exit; | |
228 | } | |
229 | } | |
230 | ||
231 | /* let the kset specific function add its stuff */ | |
232 | if (uevent_ops && uevent_ops->uevent) { | |
233 | retval = uevent_ops->uevent(kset, kobj, env); | |
234 | if (retval) { | |
235 | pr_debug("kobject: '%s' (%p): %s: uevent() returned " | |
236 | "%d\n", kobject_name(kobj), kobj, | |
237 | __func__, retval); | |
238 | goto exit; | |
239 | } | |
240 | } | |
241 | ||
242 | /* | |
243 | * Mark "add" and "remove" events in the object to ensure proper | |
244 | * events to userspace during automatic cleanup. If the object did | |
245 | * send an "add" event, "remove" will automatically generated by | |
246 | * the core, if not already done by the caller. | |
247 | */ | |
248 | if (action == KOBJ_ADD) | |
249 | kobj->state_add_uevent_sent = 1; | |
250 | else if (action == KOBJ_REMOVE) | |
251 | kobj->state_remove_uevent_sent = 1; | |
252 | ||
253 | mutex_lock(&uevent_sock_mutex); | |
254 | /* we will send an event, so request a new sequence number */ | |
255 | retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum); | |
256 | if (retval) { | |
257 | mutex_unlock(&uevent_sock_mutex); | |
258 | goto exit; | |
259 | } | |
260 | ||
261 | #if defined(CONFIG_NET) | |
262 | /* send netlink message */ | |
263 | list_for_each_entry(ue_sk, &uevent_sock_list, list) { | |
264 | struct sock *uevent_sock = ue_sk->sk; | |
265 | struct sk_buff *skb; | |
266 | size_t len; | |
267 | ||
268 | if (!netlink_has_listeners(uevent_sock, 1)) | |
269 | continue; | |
270 | ||
271 | /* allocate message with the maximum possible size */ | |
272 | len = strlen(action_string) + strlen(devpath) + 2; | |
273 | skb = alloc_skb(len + env->buflen, GFP_KERNEL); | |
274 | if (skb) { | |
275 | char *scratch; | |
276 | ||
277 | /* add header */ | |
278 | scratch = skb_put(skb, len); | |
279 | sprintf(scratch, "%s@%s", action_string, devpath); | |
280 | ||
281 | /* copy keys to our continuous event payload buffer */ | |
282 | for (i = 0; i < env->envp_idx; i++) { | |
283 | len = strlen(env->envp[i]) + 1; | |
284 | scratch = skb_put(skb, len); | |
285 | strcpy(scratch, env->envp[i]); | |
286 | } | |
287 | ||
288 | NETLINK_CB(skb).dst_group = 1; | |
289 | retval = netlink_broadcast_filtered(uevent_sock, skb, | |
290 | 0, 1, GFP_KERNEL, | |
291 | kobj_bcast_filter, | |
292 | kobj); | |
293 | /* ENOBUFS should be handled in userspace */ | |
294 | if (retval == -ENOBUFS || retval == -ESRCH) | |
295 | retval = 0; | |
296 | } else | |
297 | retval = -ENOMEM; | |
298 | } | |
299 | #endif | |
300 | mutex_unlock(&uevent_sock_mutex); | |
301 | ||
302 | /* call uevent_helper, usually only enabled during early boot */ | |
303 | if (uevent_helper[0] && !kobj_usermode_filter(kobj)) { | |
304 | char *argv [3]; | |
305 | ||
306 | argv [0] = uevent_helper; | |
307 | argv [1] = (char *)subsystem; | |
308 | argv [2] = NULL; | |
309 | retval = add_uevent_var(env, "HOME=/"); | |
310 | if (retval) | |
311 | goto exit; | |
312 | retval = add_uevent_var(env, | |
313 | "PATH=/sbin:/bin:/usr/sbin:/usr/bin"); | |
314 | if (retval) | |
315 | goto exit; | |
316 | ||
317 | retval = call_usermodehelper(argv[0], argv, | |
318 | env->envp, UMH_WAIT_EXEC); | |
319 | } | |
320 | ||
321 | exit: | |
322 | kfree(devpath); | |
323 | kfree(env); | |
324 | return retval; | |
325 | } | |
326 | EXPORT_SYMBOL_GPL(kobject_uevent_env); | |
327 | ||
328 | /** | |
329 | * kobject_uevent - notify userspace by sending an uevent | |
330 | * | |
331 | * @action: action that is happening | |
332 | * @kobj: struct kobject that the action is happening to | |
333 | * | |
334 | * Returns 0 if kobject_uevent() is completed with success or the | |
335 | * corresponding error when it fails. | |
336 | */ | |
337 | int kobject_uevent(struct kobject *kobj, enum kobject_action action) | |
338 | { | |
339 | return kobject_uevent_env(kobj, action, NULL); | |
340 | } | |
341 | EXPORT_SYMBOL_GPL(kobject_uevent); | |
342 | ||
343 | /** | |
344 | * add_uevent_var - add key value string to the environment buffer | |
345 | * @env: environment buffer structure | |
346 | * @format: printf format for the key=value pair | |
347 | * | |
348 | * Returns 0 if environment variable was added successfully or -ENOMEM | |
349 | * if no space was available. | |
350 | */ | |
351 | int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) | |
352 | { | |
353 | va_list args; | |
354 | int len; | |
355 | ||
356 | if (env->envp_idx >= ARRAY_SIZE(env->envp)) { | |
357 | WARN(1, KERN_ERR "add_uevent_var: too many keys\n"); | |
358 | return -ENOMEM; | |
359 | } | |
360 | ||
361 | va_start(args, format); | |
362 | len = vsnprintf(&env->buf[env->buflen], | |
363 | sizeof(env->buf) - env->buflen, | |
364 | format, args); | |
365 | va_end(args); | |
366 | ||
367 | if (len >= (sizeof(env->buf) - env->buflen)) { | |
368 | WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n"); | |
369 | return -ENOMEM; | |
370 | } | |
371 | ||
372 | env->envp[env->envp_idx++] = &env->buf[env->buflen]; | |
373 | env->buflen += len + 1; | |
374 | return 0; | |
375 | } | |
376 | EXPORT_SYMBOL_GPL(add_uevent_var); | |
377 | ||
378 | #if defined(CONFIG_NET) | |
379 | static int uevent_net_init(struct net *net) | |
380 | { | |
381 | struct uevent_sock *ue_sk; | |
382 | struct netlink_kernel_cfg cfg = { | |
383 | .groups = 1, | |
384 | .flags = NL_CFG_F_NONROOT_RECV, | |
385 | }; | |
386 | ||
387 | ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL); | |
388 | if (!ue_sk) | |
389 | return -ENOMEM; | |
390 | ||
391 | ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg); | |
392 | if (!ue_sk->sk) { | |
393 | printk(KERN_ERR | |
394 | "kobject_uevent: unable to create netlink socket!\n"); | |
395 | kfree(ue_sk); | |
396 | return -ENODEV; | |
397 | } | |
398 | mutex_lock(&uevent_sock_mutex); | |
399 | list_add_tail(&ue_sk->list, &uevent_sock_list); | |
400 | mutex_unlock(&uevent_sock_mutex); | |
401 | return 0; | |
402 | } | |
403 | ||
404 | static void uevent_net_exit(struct net *net) | |
405 | { | |
406 | struct uevent_sock *ue_sk; | |
407 | ||
408 | mutex_lock(&uevent_sock_mutex); | |
409 | list_for_each_entry(ue_sk, &uevent_sock_list, list) { | |
410 | if (sock_net(ue_sk->sk) == net) | |
411 | goto found; | |
412 | } | |
413 | mutex_unlock(&uevent_sock_mutex); | |
414 | return; | |
415 | ||
416 | found: | |
417 | list_del(&ue_sk->list); | |
418 | mutex_unlock(&uevent_sock_mutex); | |
419 | ||
420 | netlink_kernel_release(ue_sk->sk); | |
421 | kfree(ue_sk); | |
422 | } | |
423 | ||
424 | static struct pernet_operations uevent_net_ops = { | |
425 | .init = uevent_net_init, | |
426 | .exit = uevent_net_exit, | |
427 | }; | |
428 | ||
429 | static int __init kobject_uevent_init(void) | |
430 | { | |
431 | return register_pernet_subsys(&uevent_net_ops); | |
432 | } | |
433 | ||
434 | ||
435 | postcore_initcall(kobject_uevent_init); | |
436 | #endif |