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