lib/kobject_uevent.c

   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                 if (!netlink_has_listeners(uevent_sock, 1))
 262                         continue;
 263
 264                 /* allocate message with the maximum possible size */
 265                 len = strlen(action_string) + strlen(devpath) + 2;
 266                 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
 267                 if (skb) {
 268                         char *scratch;
 269
 270                         /* add header */
 271                         scratch = skb_put(skb, len);
 272                         sprintf(scratch, "%s@%s", action_string, devpath);
 273
 274                         /* copy keys to our continuous event payload buffer */
 275                         for (i = 0; i < env->envp_idx; i++) {
 276                                 len = strlen(env->envp[i]) + 1;
 277                                 scratch = skb_put(skb, len);
 278                                 strcpy(scratch, env->envp[i]);
 279                         }
 280
 281                         NETLINK_CB(skb).dst_group = 1;
 282                         retval = netlink_broadcast_filtered(uevent_sock, skb,
 283                                                             0, 1, GFP_KERNEL,
 284                                                             kobj_bcast_filter,
 285                                                             kobj);
 286                         /* ENOBUFS should be handled in userspace */
 287                         if (retval == -ENOBUFS || retval == -ESRCH)
 288                                 retval = 0;
 289                 } else
 290                         retval = -ENOMEM;
 291         }
 292 #endif
 293         mutex_unlock(&uevent_sock_mutex);
 294
 295         /* call uevent_helper, usually only enabled during early boot */
 296         if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
 297                 char *argv [3];
 298
 299                 argv [0] = uevent_helper;
 300                 argv [1] = (char *)subsystem;
 301                 argv [2] = NULL;
 302                 retval = add_uevent_var(env, "HOME=/");
 303                 if (retval)
 304                         goto exit;
 305                 retval = add_uevent_var(env,
 306                                         "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
 307                 if (retval)
 308                         goto exit;
 309
 310                 retval = call_usermodehelper(argv[0], argv,
 311                                              env->envp, UMH_WAIT_EXEC);
 312         }
 313
 314 exit:
 315         kfree(devpath);
 316         kfree(env);
 317         return retval;
 318 }
 319 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 320
 321 /**
 322  * kobject_uevent - notify userspace by sending an uevent
 323  *
 324  * @action: action that is happening
 325  * @kobj: struct kobject that the action is happening to
 326  *
 327  * Returns 0 if kobject_uevent() is completed with success or the
 328  * corresponding error when it fails.
 329  */
 330 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 331 {
 332         return kobject_uevent_env(kobj, action, NULL);
 333 }
 334 EXPORT_SYMBOL_GPL(kobject_uevent);
 335
 336 /**
 337  * add_uevent_var - add key value string to the environment buffer
 338  * @env: environment buffer structure
 339  * @format: printf format for the key=value pair
 340  *
 341  * Returns 0 if environment variable was added successfully or -ENOMEM
 342  * if no space was available.
 343  */
 344 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 345 {
 346         va_list args;
 347         int len;
 348
 349         if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
 350                 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
 351                 return -ENOMEM;
 352         }
 353
 354         va_start(args, format);
 355         len = vsnprintf(&env->buf[env->buflen],
 356                         sizeof(env->buf) - env->buflen,
 357                         format, args);
 358         va_end(args);
 359
 360         if (len >= (sizeof(env->buf) - env->buflen)) {
 361                 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
 362                 return -ENOMEM;
 363         }
 364
 365         env->envp[env->envp_idx++] = &env->buf[env->buflen];
 366         env->buflen += len + 1;
 367         return 0;
 368 }
 369 EXPORT_SYMBOL_GPL(add_uevent_var);
 370
 371 #if defined(CONFIG_NET)
 372 static int uevent_net_init(struct net *net)
 373 {
 374         struct uevent_sock *ue_sk;
 375
 376         ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
 377         if (!ue_sk)
 378                 return -ENOMEM;
 379
 380         ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT,
 381                                           1, NULL, NULL, THIS_MODULE);
 382         if (!ue_sk->sk) {
 383                 printk(KERN_ERR
 384                        "kobject_uevent: unable to create netlink socket!\n");
 385                 kfree(ue_sk);
 386                 return -ENODEV;
 387         }
 388         mutex_lock(&uevent_sock_mutex);
 389         list_add_tail(&ue_sk->list, &uevent_sock_list);
 390         mutex_unlock(&uevent_sock_mutex);
 391         return 0;
 392 }
 393
 394 static void uevent_net_exit(struct net *net)
 395 {
 396         struct uevent_sock *ue_sk;
 397
 398         mutex_lock(&uevent_sock_mutex);
 399         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 400                 if (sock_net(ue_sk->sk) == net)
 401                         goto found;
 402         }
 403         mutex_unlock(&uevent_sock_mutex);
 404         return;
 405
 406 found:
 407         list_del(&ue_sk->list);
 408         mutex_unlock(&uevent_sock_mutex);
 409
 410         netlink_kernel_release(ue_sk->sk);
 411         kfree(ue_sk);
 412 }
 413
 414 static struct pernet_operations uevent_net_ops = {
 415         .init   = uevent_net_init,
 416         .exit   = uevent_net_exit,
 417 };
 418
 419 static int __init kobject_uevent_init(void)
 420 {
 421         netlink_set_nonroot(NETLINK_KOBJECT_UEVENT, NL_NONROOT_RECV);
 422         return register_pernet_subsys(&uevent_net_ops);
 423 }
 424
 425
 426 postcore_initcall(kobject_uevent_init);
 427 #endif