projects/linux·blob v3.13 · refs

430 lines · 10.4 KiB

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