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TOMOYO Linux Cross Reference
Linux/lib/kobject_uevent.c

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

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