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/socket.h>
24 #include <linux/skbuff.h>
25 #include <linux/netlink.h>
26 #include <net/sock.h>
27 #include <net/net_namespace.h>
28
29
30 u64 uevent_seqnum;
31 #ifdef CONFIG_UEVENT_HELPER
32 char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
33 #endif
34 #ifdef CONFIG_NET
35 struct uevent_sock {
36 struct list_head list;
37 struct sock *sk;
38 };
39 static LIST_HEAD(uevent_sock_list);
40 #endif
41
42 /* This lock protects uevent_seqnum and uevent_sock_list */
43 static DEFINE_MUTEX(uevent_sock_mutex);
44
45 /* the strings here must match the enum in include/linux/kobject.h */
46 static const char *kobject_actions[] = {
47 [KOBJ_ADD] = "add",
48 [KOBJ_REMOVE] = "remove",
49 [KOBJ_CHANGE] = "change",
50 [KOBJ_MOVE] = "move",
51 [KOBJ_ONLINE] = "online",
52 [KOBJ_OFFLINE] = "offline",
53 };
54
55 /**
56 * kobject_action_type - translate action string to numeric type
57 *
58 * @buf: buffer containing the action string, newline is ignored
59 * @len: length of buffer
60 * @type: pointer to the location to store the action type
61 *
62 * Returns 0 if the action string was recognized.
63 */
kobject_action_type(const char * buf,size_t count,enum kobject_action * type)64 int kobject_action_type(const char *buf, size_t count,
65 enum kobject_action *type)
66 {
67 enum kobject_action action;
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 for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
77 if (strncmp(kobject_actions[action], buf, count) != 0)
78 continue;
79 if (kobject_actions[action][count] != '\0')
80 continue;
81 *type = action;
82 ret = 0;
83 break;
84 }
85 out:
86 return ret;
87 }
88
89 #ifdef CONFIG_NET
kobj_bcast_filter(struct sock * dsk,struct sk_buff * skb,void * data)90 static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data)
91 {
92 struct kobject *kobj = data, *ksobj;
93 const struct kobj_ns_type_operations *ops;
94
95 ops = kobj_ns_ops(kobj);
96 if (!ops && kobj->kset) {
97 ksobj = &kobj->kset->kobj;
98 if (ksobj->parent != NULL)
99 ops = kobj_ns_ops(ksobj->parent);
100 }
101
102 if (ops && ops->netlink_ns && kobj->ktype->namespace) {
103 const void *sock_ns, *ns;
104 ns = kobj->ktype->namespace(kobj);
105 sock_ns = ops->netlink_ns(dsk);
106 return sock_ns != ns;
107 }
108
109 return 0;
110 }
111 #endif
112
113 #ifdef CONFIG_UEVENT_HELPER
kobj_usermode_filter(struct kobject * kobj)114 static int kobj_usermode_filter(struct kobject *kobj)
115 {
116 const struct kobj_ns_type_operations *ops;
117
118 ops = kobj_ns_ops(kobj);
119 if (ops) {
120 const void *init_ns, *ns;
121 ns = kobj->ktype->namespace(kobj);
122 init_ns = ops->initial_ns();
123 return ns != init_ns;
124 }
125
126 return 0;
127 }
128
init_uevent_argv(struct kobj_uevent_env * env,const char * subsystem)129 static int init_uevent_argv(struct kobj_uevent_env *env, const char *subsystem)
130 {
131 int buffer_size = sizeof(env->buf) - env->buflen;
132 int len;
133
134 len = strlcpy(&env->buf[env->buflen], subsystem, buffer_size);
135 if (len >= buffer_size) {
136 pr_warn("init_uevent_argv: buffer size of %d too small, needed %d\n",
137 buffer_size, len);
138 return -ENOMEM;
139 }
140
141 env->argv[0] = uevent_helper;
142 env->argv[1] = &env->buf[env->buflen];
143 env->argv[2] = NULL;
144
145 env->buflen += len + 1;
146 return 0;
147 }
148
cleanup_uevent_env(struct subprocess_info * info)149 static void cleanup_uevent_env(struct subprocess_info *info)
150 {
151 kfree(info->data);
152 }
153 #endif
154
155 /**
156 * kobject_uevent_env - send an uevent with environmental data
157 *
158 * @action: action that is happening
159 * @kobj: struct kobject that the action is happening to
160 * @envp_ext: pointer to environmental data
161 *
162 * Returns 0 if kobject_uevent_env() is completed with success or the
163 * corresponding error when it fails.
164 */
kobject_uevent_env(struct kobject * kobj,enum kobject_action action,char * envp_ext[])165 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
166 char *envp_ext[])
167 {
168 struct kobj_uevent_env *env;
169 const char *action_string = kobject_actions[action];
170 const char *devpath = NULL;
171 const char *subsystem;
172 struct kobject *top_kobj;
173 struct kset *kset;
174 const struct kset_uevent_ops *uevent_ops;
175 int i = 0;
176 int retval = 0;
177 #ifdef CONFIG_NET
178 struct uevent_sock *ue_sk;
179 #endif
180
181 pr_debug("kobject: '%s' (%p): %s\n",
182 kobject_name(kobj), kobj, __func__);
183
184 /* search the kset we belong to */
185 top_kobj = kobj;
186 while (!top_kobj->kset && top_kobj->parent)
187 top_kobj = top_kobj->parent;
188
189 if (!top_kobj->kset) {
190 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
191 "without kset!\n", kobject_name(kobj), kobj,
192 __func__);
193 return -EINVAL;
194 }
195
196 kset = top_kobj->kset;
197 uevent_ops = kset->uevent_ops;
198
199 /* skip the event, if uevent_suppress is set*/
200 if (kobj->uevent_suppress) {
201 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
202 "caused the event to drop!\n",
203 kobject_name(kobj), kobj, __func__);
204 return 0;
205 }
206 /* skip the event, if the filter returns zero. */
207 if (uevent_ops && uevent_ops->filter)
208 if (!uevent_ops->filter(kset, kobj)) {
209 pr_debug("kobject: '%s' (%p): %s: filter function "
210 "caused the event to drop!\n",
211 kobject_name(kobj), kobj, __func__);
212 return 0;
213 }
214
215 /* originating subsystem */
216 if (uevent_ops && uevent_ops->name)
217 subsystem = uevent_ops->name(kset, kobj);
218 else
219 subsystem = kobject_name(&kset->kobj);
220 if (!subsystem) {
221 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
222 "event to drop!\n", kobject_name(kobj), kobj,
223 __func__);
224 return 0;
225 }
226
227 /* environment buffer */
228 env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
229 if (!env)
230 return -ENOMEM;
231
232 /* complete object path */
233 devpath = kobject_get_path(kobj, GFP_KERNEL);
234 if (!devpath) {
235 retval = -ENOENT;
236 goto exit;
237 }
238
239 /* default keys */
240 retval = add_uevent_var(env, "ACTION=%s", action_string);
241 if (retval)
242 goto exit;
243 retval = add_uevent_var(env, "DEVPATH=%s", devpath);
244 if (retval)
245 goto exit;
246 retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
247 if (retval)
248 goto exit;
249
250 /* keys passed in from the caller */
251 if (envp_ext) {
252 for (i = 0; envp_ext[i]; i++) {
253 retval = add_uevent_var(env, "%s", envp_ext[i]);
254 if (retval)
255 goto exit;
256 }
257 }
258
259 /* let the kset specific function add its stuff */
260 if (uevent_ops && uevent_ops->uevent) {
261 retval = uevent_ops->uevent(kset, kobj, env);
262 if (retval) {
263 pr_debug("kobject: '%s' (%p): %s: uevent() returned "
264 "%d\n", kobject_name(kobj), kobj,
265 __func__, retval);
266 goto exit;
267 }
268 }
269
270 /*
271 * Mark "add" and "remove" events in the object to ensure proper
272 * events to userspace during automatic cleanup. If the object did
273 * send an "add" event, "remove" will automatically generated by
274 * the core, if not already done by the caller.
275 */
276 if (action == KOBJ_ADD)
277 kobj->state_add_uevent_sent = 1;
278 else if (action == KOBJ_REMOVE)
279 kobj->state_remove_uevent_sent = 1;
280
281 mutex_lock(&uevent_sock_mutex);
282 /* we will send an event, so request a new sequence number */
283 retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum);
284 if (retval) {
285 mutex_unlock(&uevent_sock_mutex);
286 goto exit;
287 }
288
289 #if defined(CONFIG_NET)
290 /* send netlink message */
291 list_for_each_entry(ue_sk, &uevent_sock_list, list) {
292 struct sock *uevent_sock = ue_sk->sk;
293 struct sk_buff *skb;
294 size_t len;
295
296 if (!netlink_has_listeners(uevent_sock, 1))
297 continue;
298
299 /* allocate message with the maximum possible size */
300 len = strlen(action_string) + strlen(devpath) + 2;
301 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
302 if (skb) {
303 char *scratch;
304
305 /* add header */
306 scratch = skb_put(skb, len);
307 sprintf(scratch, "%s@%s", action_string, devpath);
308
309 /* copy keys to our continuous event payload buffer */
310 for (i = 0; i < env->envp_idx; i++) {
311 len = strlen(env->envp[i]) + 1;
312 scratch = skb_put(skb, len);
313 strcpy(scratch, env->envp[i]);
314 }
315
316 NETLINK_CB(skb).dst_group = 1;
317 retval = netlink_broadcast_filtered(uevent_sock, skb,
318 0, 1, GFP_KERNEL,
319 kobj_bcast_filter,
320 kobj);
321 /* ENOBUFS should be handled in userspace */
322 if (retval == -ENOBUFS || retval == -ESRCH)
323 retval = 0;
324 } else
325 retval = -ENOMEM;
326 }
327 #endif
328 mutex_unlock(&uevent_sock_mutex);
329
330 #ifdef CONFIG_UEVENT_HELPER
331 /* call uevent_helper, usually only enabled during early boot */
332 if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
333 struct subprocess_info *info;
334
335 retval = add_uevent_var(env, "HOME=/");
336 if (retval)
337 goto exit;
338 retval = add_uevent_var(env,
339 "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
340 if (retval)
341 goto exit;
342 retval = init_uevent_argv(env, subsystem);
343 if (retval)
344 goto exit;
345
346 retval = -ENOMEM;
347 info = call_usermodehelper_setup(env->argv[0], env->argv,
348 env->envp, GFP_KERNEL,
349 NULL, cleanup_uevent_env, env);
350 if (info) {
351 retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
352 env = NULL; /* freed by cleanup_uevent_env */
353 }
354 }
355 #endif
356
357 exit:
358 kfree(devpath);
359 kfree(env);
360 return retval;
361 }
362 EXPORT_SYMBOL_GPL(kobject_uevent_env);
363
364 /**
365 * kobject_uevent - notify userspace by sending an uevent
366 *
367 * @action: action that is happening
368 * @kobj: struct kobject that the action is happening to
369 *
370 * Returns 0 if kobject_uevent() is completed with success or the
371 * corresponding error when it fails.
372 */
kobject_uevent(struct kobject * kobj,enum kobject_action action)373 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
374 {
375 return kobject_uevent_env(kobj, action, NULL);
376 }
377 EXPORT_SYMBOL_GPL(kobject_uevent);
378
379 /**
380 * add_uevent_var - add key value string to the environment buffer
381 * @env: environment buffer structure
382 * @format: printf format for the key=value pair
383 *
384 * Returns 0 if environment variable was added successfully or -ENOMEM
385 * if no space was available.
386 */
add_uevent_var(struct kobj_uevent_env * env,const char * format,...)387 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
388 {
389 va_list args;
390 int len;
391
392 if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
393 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
394 return -ENOMEM;
395 }
396
397 va_start(args, format);
398 len = vsnprintf(&env->buf[env->buflen],
399 sizeof(env->buf) - env->buflen,
400 format, args);
401 va_end(args);
402
403 if (len >= (sizeof(env->buf) - env->buflen)) {
404 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
405 return -ENOMEM;
406 }
407
408 env->envp[env->envp_idx++] = &env->buf[env->buflen];
409 env->buflen += len + 1;
410 return 0;
411 }
412 EXPORT_SYMBOL_GPL(add_uevent_var);
413
414 #if defined(CONFIG_NET)
uevent_net_init(struct net * net)415 static int uevent_net_init(struct net *net)
416 {
417 struct uevent_sock *ue_sk;
418 struct netlink_kernel_cfg cfg = {
419 .groups = 1,
420 .flags = NL_CFG_F_NONROOT_RECV,
421 };
422
423 ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
424 if (!ue_sk)
425 return -ENOMEM;
426
427 ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
428 if (!ue_sk->sk) {
429 printk(KERN_ERR
430 "kobject_uevent: unable to create netlink socket!\n");
431 kfree(ue_sk);
432 return -ENODEV;
433 }
434 mutex_lock(&uevent_sock_mutex);
435 list_add_tail(&ue_sk->list, &uevent_sock_list);
436 mutex_unlock(&uevent_sock_mutex);
437 return 0;
438 }
439
uevent_net_exit(struct net * net)440 static void uevent_net_exit(struct net *net)
441 {
442 struct uevent_sock *ue_sk;
443
444 mutex_lock(&uevent_sock_mutex);
445 list_for_each_entry(ue_sk, &uevent_sock_list, list) {
446 if (sock_net(ue_sk->sk) == net)
447 goto found;
448 }
449 mutex_unlock(&uevent_sock_mutex);
450 return;
451
452 found:
453 list_del(&ue_sk->list);
454 mutex_unlock(&uevent_sock_mutex);
455
456 netlink_kernel_release(ue_sk->sk);
457 kfree(ue_sk);
458 }
459
460 static struct pernet_operations uevent_net_ops = {
461 .init = uevent_net_init,
462 .exit = uevent_net_exit,
463 };
464
kobject_uevent_init(void)465 static int __init kobject_uevent_init(void)
466 {
467 return register_pernet_subsys(&uevent_net_ops);
468 }
469
470
471 postcore_initcall(kobject_uevent_init);
472 #endif
473