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/module.h>
21
22 #include <linux/socket.h>
23 #include <linux/skbuff.h>
24 #include <linux/netlink.h>
25 #include <net/sock.h>
26
27
28 u64 uevent_seqnum;
29 char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
30 static DEFINE_SPINLOCK(sequence_lock);
31 #if defined(CONFIG_NET)
32 static struct sock *uevent_sock;
33 #endif
34
35 /* the strings here must match the enum in include/linux/kobject.h */
36 static const char *kobject_actions[] = {
37 [KOBJ_ADD] = "add",
38 [KOBJ_REMOVE] = "remove",
39 [KOBJ_CHANGE] = "change",
40 [KOBJ_MOVE] = "move",
41 [KOBJ_ONLINE] = "online",
42 [KOBJ_OFFLINE] = "offline",
43 };
44
45 /**
46 * kobject_action_type - translate action string to numeric type
47 *
48 * @buf: buffer containing the action string, newline is ignored
49 * @len: length of buffer
50 * @type: pointer to the location to store the action type
51 *
52 * Returns 0 if the action string was recognized.
53 */
kobject_action_type(const char * buf,size_t count,enum kobject_action * type)54 int kobject_action_type(const char *buf, size_t count,
55 enum kobject_action *type)
56 {
57 enum kobject_action action;
58 int ret = -EINVAL;
59
60 if (count && (buf[count-1] == '\n' || buf[count-1] == '\0'))
61 count--;
62
63 if (!count)
64 goto out;
65
66 for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
67 if (strncmp(kobject_actions[action], buf, count) != 0)
68 continue;
69 if (kobject_actions[action][count] != '\0')
70 continue;
71 *type = action;
72 ret = 0;
73 break;
74 }
75 out:
76 return ret;
77 }
78
79 /**
80 * kobject_uevent_env - send an uevent with environmental data
81 *
82 * @action: action that is happening
83 * @kobj: struct kobject that the action is happening to
84 * @envp_ext: pointer to environmental data
85 *
86 * Returns 0 if kobject_uevent() is completed with success or the
87 * corresponding error when it fails.
88 */
kobject_uevent_env(struct kobject * kobj,enum kobject_action action,char * envp_ext[])89 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
90 char *envp_ext[])
91 {
92 struct kobj_uevent_env *env;
93 const char *action_string = kobject_actions[action];
94 const char *devpath = NULL;
95 const char *subsystem;
96 struct kobject *top_kobj;
97 struct kset *kset;
98 struct kset_uevent_ops *uevent_ops;
99 u64 seq;
100 int i = 0;
101 int retval = 0;
102
103 pr_debug("kobject: '%s' (%p): %s\n",
104 kobject_name(kobj), kobj, __func__);
105
106 /* search the kset we belong to */
107 top_kobj = kobj;
108 while (!top_kobj->kset && top_kobj->parent)
109 top_kobj = top_kobj->parent;
110
111 if (!top_kobj->kset) {
112 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
113 "without kset!\n", kobject_name(kobj), kobj,
114 __func__);
115 return -EINVAL;
116 }
117
118 kset = top_kobj->kset;
119 uevent_ops = kset->uevent_ops;
120
121 /* skip the event, if the filter returns zero. */
122 if (uevent_ops && uevent_ops->filter)
123 if (!uevent_ops->filter(kset, kobj)) {
124 pr_debug("kobject: '%s' (%p): %s: filter function "
125 "caused the event to drop!\n",
126 kobject_name(kobj), kobj, __func__);
127 return 0;
128 }
129
130 /* originating subsystem */
131 if (uevent_ops && uevent_ops->name)
132 subsystem = uevent_ops->name(kset, kobj);
133 else
134 subsystem = kobject_name(&kset->kobj);
135 if (!subsystem) {
136 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
137 "event to drop!\n", kobject_name(kobj), kobj,
138 __func__);
139 return 0;
140 }
141
142 /* environment buffer */
143 env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
144 if (!env)
145 return -ENOMEM;
146
147 /* complete object path */
148 devpath = kobject_get_path(kobj, GFP_KERNEL);
149 if (!devpath) {
150 retval = -ENOENT;
151 goto exit;
152 }
153
154 /* default keys */
155 retval = add_uevent_var(env, "ACTION=%s", action_string);
156 if (retval)
157 goto exit;
158 retval = add_uevent_var(env, "DEVPATH=%s", devpath);
159 if (retval)
160 goto exit;
161 retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
162 if (retval)
163 goto exit;
164
165 /* keys passed in from the caller */
166 if (envp_ext) {
167 for (i = 0; envp_ext[i]; i++) {
168 retval = add_uevent_var(env, "%s", envp_ext[i]);
169 if (retval)
170 goto exit;
171 }
172 }
173
174 /* let the kset specific function add its stuff */
175 if (uevent_ops && uevent_ops->uevent) {
176 retval = uevent_ops->uevent(kset, kobj, env);
177 if (retval) {
178 pr_debug("kobject: '%s' (%p): %s: uevent() returned "
179 "%d\n", kobject_name(kobj), kobj,
180 __func__, retval);
181 goto exit;
182 }
183 }
184
185 /*
186 * Mark "add" and "remove" events in the object to ensure proper
187 * events to userspace during automatic cleanup. If the object did
188 * send an "add" event, "remove" will automatically generated by
189 * the core, if not already done by the caller.
190 */
191 if (action == KOBJ_ADD)
192 kobj->state_add_uevent_sent = 1;
193 else if (action == KOBJ_REMOVE)
194 kobj->state_remove_uevent_sent = 1;
195
196 /* we will send an event, so request a new sequence number */
197 spin_lock(&sequence_lock);
198 seq = ++uevent_seqnum;
199 spin_unlock(&sequence_lock);
200 retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)seq);
201 if (retval)
202 goto exit;
203
204 #if defined(CONFIG_NET)
205 /* send netlink message */
206 if (uevent_sock) {
207 struct sk_buff *skb;
208 size_t len;
209
210 /* allocate message with the maximum possible size */
211 len = strlen(action_string) + strlen(devpath) + 2;
212 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
213 if (skb) {
214 char *scratch;
215
216 /* add header */
217 scratch = skb_put(skb, len);
218 sprintf(scratch, "%s@%s", action_string, devpath);
219
220 /* copy keys to our continuous event payload buffer */
221 for (i = 0; i < env->envp_idx; i++) {
222 len = strlen(env->envp[i]) + 1;
223 scratch = skb_put(skb, len);
224 strcpy(scratch, env->envp[i]);
225 }
226
227 NETLINK_CB(skb).dst_group = 1;
228 retval = netlink_broadcast(uevent_sock, skb, 0, 1,
229 GFP_KERNEL);
230 } else
231 retval = -ENOMEM;
232 }
233 #endif
234
235 /* call uevent_helper, usually only enabled during early boot */
236 if (uevent_helper[0]) {
237 char *argv [3];
238
239 argv [0] = uevent_helper;
240 argv [1] = (char *)subsystem;
241 argv [2] = NULL;
242 retval = add_uevent_var(env, "HOME=/");
243 if (retval)
244 goto exit;
245 retval = add_uevent_var(env,
246 "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
247 if (retval)
248 goto exit;
249
250 retval = call_usermodehelper(argv[0], argv,
251 env->envp, UMH_WAIT_EXEC);
252 }
253
254 exit:
255 kfree(devpath);
256 kfree(env);
257 return retval;
258 }
259 EXPORT_SYMBOL_GPL(kobject_uevent_env);
260
261 /**
262 * kobject_uevent - notify userspace by ending an uevent
263 *
264 * @action: action that is happening
265 * @kobj: struct kobject that the action is happening to
266 *
267 * Returns 0 if kobject_uevent() is completed with success or the
268 * corresponding error when it fails.
269 */
kobject_uevent(struct kobject * kobj,enum kobject_action action)270 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
271 {
272 return kobject_uevent_env(kobj, action, NULL);
273 }
274 EXPORT_SYMBOL_GPL(kobject_uevent);
275
276 /**
277 * add_uevent_var - add key value string to the environment buffer
278 * @env: environment buffer structure
279 * @format: printf format for the key=value pair
280 *
281 * Returns 0 if environment variable was added successfully or -ENOMEM
282 * if no space was available.
283 */
add_uevent_var(struct kobj_uevent_env * env,const char * format,...)284 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
285 {
286 va_list args;
287 int len;
288
289 if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
290 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
291 return -ENOMEM;
292 }
293
294 va_start(args, format);
295 len = vsnprintf(&env->buf[env->buflen],
296 sizeof(env->buf) - env->buflen,
297 format, args);
298 va_end(args);
299
300 if (len >= (sizeof(env->buf) - env->buflen)) {
301 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
302 return -ENOMEM;
303 }
304
305 env->envp[env->envp_idx++] = &env->buf[env->buflen];
306 env->buflen += len + 1;
307 return 0;
308 }
309 EXPORT_SYMBOL_GPL(add_uevent_var);
310
311 #if defined(CONFIG_NET)
kobject_uevent_init(void)312 static int __init kobject_uevent_init(void)
313 {
314 uevent_sock = netlink_kernel_create(&init_net, NETLINK_KOBJECT_UEVENT,
315 1, NULL, NULL, THIS_MODULE);
316 if (!uevent_sock) {
317 printk(KERN_ERR
318 "kobject_uevent: unable to create netlink socket!\n");
319 return -ENODEV;
320 }
321
322 return 0;
323 }
324
325 postcore_initcall(kobject_uevent_init);
326 #endif
327