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/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
  31 u64 uevent_seqnum;
  32 #ifdef CONFIG_UEVENT_HELPER
  33 char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
  34 #endif
  35 #ifdef CONFIG_NET
  36 struct uevent_sock {
  37         struct list_head list;
  38         struct sock *sk;
  39 };
  40 static LIST_HEAD(uevent_sock_list);
  41 #endif
  42
  43 /* This lock protects uevent_seqnum and uevent_sock_list */
  44 static DEFINE_MUTEX(uevent_sock_mutex);
  45
  46 /* the strings here must match the enum in include/linux/kobject.h */
  47 static const char *kobject_actions[] = {
  48         [KOBJ_ADD] =            "add",
  49         [KOBJ_REMOVE] =         "remove",
  50         [KOBJ_CHANGE] =         "change",
  51         [KOBJ_MOVE] =           "move",
  52         [KOBJ_ONLINE] =         "online",
  53         [KOBJ_OFFLINE] =        "offline",
  54 };
  55
  56 /**
  57  * kobject_action_type - translate action string to numeric type
  58  *
  59  * @buf: buffer containing the action string, newline is ignored
  60  * @len: length of buffer
  61  * @type: pointer to the location to store the action type
  62  *
  63  * Returns 0 if the action string was recognized.
  64  */
  65 int kobject_action_type(const char *buf, size_t count,
  66                         enum kobject_action *type)
  67 {
  68         enum kobject_action action;
  69         int ret = -EINVAL;
  70
  71         if (count && (buf[count-1] == '\n' || buf[count-1] == '\0'))
  72                 count--;
  73
  74         if (!count)
  75                 goto out;
  76
  77         for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
  78                 if (strncmp(kobject_actions[action], buf, count) != 0)
  79                         continue;
  80                 if (kobject_actions[action][count] != '\0')
  81                         continue;
  82                 *type = action;
  83                 ret = 0;
  84                 break;
  85         }
  86 out:
  87         return ret;
  88 }
  89
  90 #ifdef CONFIG_NET
  91 static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data)
  92 {
  93         struct kobject *kobj = data, *ksobj;
  94         const struct kobj_ns_type_operations *ops;
  95
  96         ops = kobj_ns_ops(kobj);
  97         if (!ops && kobj->kset) {
  98                 ksobj = &kobj->kset->kobj;
  99                 if (ksobj->parent != NULL)
 100                         ops = kobj_ns_ops(ksobj->parent);
 101         }
 102
 103         if (ops && ops->netlink_ns && kobj->ktype->namespace) {
 104                 const void *sock_ns, *ns;
 105                 ns = kobj->ktype->namespace(kobj);
 106                 sock_ns = ops->netlink_ns(dsk);
 107                 return sock_ns != ns;
 108         }
 109
 110         return 0;
 111 }
 112 #endif
 113
 114 #ifdef CONFIG_UEVENT_HELPER
 115 static int kobj_usermode_filter(struct kobject *kobj)
 116 {
 117         const struct kobj_ns_type_operations *ops;
 118
 119         ops = kobj_ns_ops(kobj);
 120         if (ops) {
 121                 const void *init_ns, *ns;
 122                 ns = kobj->ktype->namespace(kobj);
 123                 init_ns = ops->initial_ns();
 124                 return ns != init_ns;
 125         }
 126
 127         return 0;
 128 }
 129
 130 static int init_uevent_argv(struct kobj_uevent_env *env, const char *subsystem)
 131 {
 132         int len;
 133
 134         len = strlcpy(&env->buf[env->buflen], subsystem,
 135                       sizeof(env->buf) - env->buflen);
 136         if (len >= (sizeof(env->buf) - env->buflen)) {
 137                 WARN(1, KERN_ERR "init_uevent_argv: buffer size too small\n");
 138                 return -ENOMEM;
 139         }
 140
 141         env->argv[0] = uevent_helper;
 142         env->argv[1] = &env->buf[env->buflen];
 143         env->argv[2] = NULL;
 144
 145         env->buflen += len + 1;
 146         return 0;
 147 }
 148
 149 static void cleanup_uevent_env(struct subprocess_info *info)
 150 {
 151         kfree(info->data);
 152 }
 153 #endif
 154
 155 /**
 156  * kobject_uevent_env - send an uevent with environmental data
 157  *
 158  * @action: action that is happening
 159  * @kobj: struct kobject that the action is happening to
 160  * @envp_ext: pointer to environmental data
 161  *
 162  * Returns 0 if kobject_uevent_env() is completed with success or the
 163  * corresponding error when it fails.
 164  */
 165 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
 166                        char *envp_ext[])
 167 {
 168         struct kobj_uevent_env *env;
 169         const char *action_string = kobject_actions[action];
 170         const char *devpath = NULL;
 171         const char *subsystem;
 172         struct kobject *top_kobj;
 173         struct kset *kset;
 174         const struct kset_uevent_ops *uevent_ops;
 175         int i = 0;
 176         int retval = 0;
 177 #ifdef CONFIG_NET
 178         struct uevent_sock *ue_sk;
 179 #endif
 180
 181         pr_debug("kobject: '%s' (%p): %s\n",
 182                  kobject_name(kobj), kobj, __func__);
 183
 184         /* search the kset we belong to */
 185         top_kobj = kobj;
 186         while (!top_kobj->kset && top_kobj->parent)
 187                 top_kobj = top_kobj->parent;
 188
 189         if (!top_kobj->kset) {
 190                 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
 191                          "without kset!\n", kobject_name(kobj), kobj,
 192                          __func__);
 193                 return -EINVAL;
 194         }
 195
 196         kset = top_kobj->kset;
 197         uevent_ops = kset->uevent_ops;
 198
 199         /* skip the event, if uevent_suppress is set*/
 200         if (kobj->uevent_suppress) {
 201                 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
 202                                  "caused the event to drop!\n",
 203                                  kobject_name(kobj), kobj, __func__);
 204                 return 0;
 205         }
 206         /* skip the event, if the filter returns zero. */
 207         if (uevent_ops && uevent_ops->filter)
 208                 if (!uevent_ops->filter(kset, kobj)) {
 209                         pr_debug("kobject: '%s' (%p): %s: filter function "
 210                                  "caused the event to drop!\n",
 211                                  kobject_name(kobj), kobj, __func__);
 212                         return 0;
 213                 }
 214
 215         /* originating subsystem */
 216         if (uevent_ops && uevent_ops->name)
 217                 subsystem = uevent_ops->name(kset, kobj);
 218         else
 219                 subsystem = kobject_name(&kset->kobj);
 220         if (!subsystem) {
 221                 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
 222                          "event to drop!\n", kobject_name(kobj), kobj,
 223                          __func__);
 224                 return 0;
 225         }
 226
 227         /* environment buffer */
 228         env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
 229         if (!env)
 230                 return -ENOMEM;
 231
 232         /* complete object path */
 233         devpath = kobject_get_path(kobj, GFP_KERNEL);
 234         if (!devpath) {
 235                 retval = -ENOENT;
 236                 goto exit;
 237         }
 238
 239         /* default keys */
 240         retval = add_uevent_var(env, "ACTION=%s", action_string);
 241         if (retval)
 242                 goto exit;
 243         retval = add_uevent_var(env, "DEVPATH=%s", devpath);
 244         if (retval)
 245                 goto exit;
 246         retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
 247         if (retval)
 248                 goto exit;
 249
 250         /* keys passed in from the caller */
 251         if (envp_ext) {
 252                 for (i = 0; envp_ext[i]; i++) {
 253                         retval = add_uevent_var(env, "%s", envp_ext[i]);
 254                         if (retval)
 255                                 goto exit;
 256                 }
 257         }
 258
 259         /* let the kset specific function add its stuff */
 260         if (uevent_ops && uevent_ops->uevent) {
 261                 retval = uevent_ops->uevent(kset, kobj, env);
 262                 if (retval) {
 263                         pr_debug("kobject: '%s' (%p): %s: uevent() returned "
 264                                  "%d\n", kobject_name(kobj), kobj,
 265                                  __func__, retval);
 266                         goto exit;
 267                 }
 268         }
 269
 270         /*
 271          * Mark "add" and "remove" events in the object to ensure proper
 272          * events to userspace during automatic cleanup. If the object did
 273          * send an "add" event, "remove" will automatically generated by
 274          * the core, if not already done by the caller.
 275          */
 276         if (action == KOBJ_ADD)
 277                 kobj->state_add_uevent_sent = 1;
 278         else if (action == KOBJ_REMOVE)
 279                 kobj->state_remove_uevent_sent = 1;
 280
 281         mutex_lock(&uevent_sock_mutex);
 282         /* we will send an event, so request a new sequence number */
 283         retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum);
 284         if (retval) {
 285                 mutex_unlock(&uevent_sock_mutex);
 286                 goto exit;
 287         }
 288
 289 #if defined(CONFIG_NET)
 290         /* send netlink message */
 291         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 292                 struct sock *uevent_sock = ue_sk->sk;
 293                 struct sk_buff *skb;
 294                 size_t len;
 295
 296                 if (!netlink_has_listeners(uevent_sock, 1))
 297                         continue;
 298
 299                 /* allocate message with the maximum possible size */
 300                 len = strlen(action_string) + strlen(devpath) + 2;
 301                 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
 302                 if (skb) {
 303                         char *scratch;
 304
 305                         /* add header */
 306                         scratch = skb_put(skb, len);
 307                         sprintf(scratch, "%s@%s", action_string, devpath);
 308
 309                         /* copy keys to our continuous event payload buffer */
 310                         for (i = 0; i < env->envp_idx; i++) {
 311                                 len = strlen(env->envp[i]) + 1;
 312                                 scratch = skb_put(skb, len);
 313                                 strcpy(scratch, env->envp[i]);
 314                         }
 315
 316                         NETLINK_CB(skb).dst_group = 1;
 317                         retval = netlink_broadcast_filtered(uevent_sock, skb,
 318                                                             0, 1, GFP_KERNEL,
 319                                                             kobj_bcast_filter,
 320                                                             kobj);
 321                         /* ENOBUFS should be handled in userspace */
 322                         if (retval == -ENOBUFS || retval == -ESRCH)
 323                                 retval = 0;
 324                 } else
 325                         retval = -ENOMEM;
 326         }
 327 #endif
 328         mutex_unlock(&uevent_sock_mutex);
 329
 330 #ifdef CONFIG_UEVENT_HELPER
 331         /* call uevent_helper, usually only enabled during early boot */
 332         if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
 333                 struct subprocess_info *info;
 334
 335                 retval = add_uevent_var(env, "HOME=/");
 336                 if (retval)
 337                         goto exit;
 338                 retval = add_uevent_var(env,
 339                                         "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
 340                 if (retval)
 341                         goto exit;
 342                 retval = init_uevent_argv(env, subsystem);
 343                 if (retval)
 344                         goto exit;
 345
 346                 retval = -ENOMEM;
 347                 info = call_usermodehelper_setup(env->argv[0], env->argv,
 348                                                  env->envp, GFP_KERNEL,
 349                                                  NULL, cleanup_uevent_env, env);
 350                 if (info) {
 351                         retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
 352                         env = NULL;     /* freed by cleanup_uevent_env */
 353                 }
 354         }
 355 #endif
 356
 357 exit:
 358         kfree(devpath);
 359         kfree(env);
 360         return retval;
 361 }
 362 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 363
 364 /**
 365  * kobject_uevent - notify userspace by sending an uevent
 366  *
 367  * @action: action that is happening
 368  * @kobj: struct kobject that the action is happening to
 369  *
 370  * Returns 0 if kobject_uevent() is completed with success or the
 371  * corresponding error when it fails.
 372  */
 373 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 374 {
 375         return kobject_uevent_env(kobj, action, NULL);
 376 }
 377 EXPORT_SYMBOL_GPL(kobject_uevent);
 378
 379 /**
 380  * add_uevent_var - add key value string to the environment buffer
 381  * @env: environment buffer structure
 382  * @format: printf format for the key=value pair
 383  *
 384  * Returns 0 if environment variable was added successfully or -ENOMEM
 385  * if no space was available.
 386  */
 387 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 388 {
 389         va_list args;
 390         int len;
 391
 392         if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
 393                 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
 394                 return -ENOMEM;
 395         }
 396
 397         va_start(args, format);
 398         len = vsnprintf(&env->buf[env->buflen],
 399                         sizeof(env->buf) - env->buflen,
 400                         format, args);
 401         va_end(args);
 402
 403         if (len >= (sizeof(env->buf) - env->buflen)) {
 404                 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
 405                 return -ENOMEM;
 406         }
 407
 408         env->envp[env->envp_idx++] = &env->buf[env->buflen];
 409         env->buflen += len + 1;
 410         return 0;
 411 }
 412 EXPORT_SYMBOL_GPL(add_uevent_var);
 413
 414 #if defined(CONFIG_NET)
 415 static int uevent_net_init(struct net *net)
 416 {
 417         struct uevent_sock *ue_sk;
 418         struct netlink_kernel_cfg cfg = {
 419                 .groups = 1,
 420                 .flags  = NL_CFG_F_NONROOT_RECV,
 421         };
 422
 423         ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
 424         if (!ue_sk)
 425                 return -ENOMEM;
 426
 427         ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
 428         if (!ue_sk->sk) {
 429                 printk(KERN_ERR
 430                        "kobject_uevent: unable to create netlink socket!\n");
 431                 kfree(ue_sk);
 432                 return -ENODEV;
 433         }
 434         mutex_lock(&uevent_sock_mutex);
 435         list_add_tail(&ue_sk->list, &uevent_sock_list);
 436         mutex_unlock(&uevent_sock_mutex);
 437         return 0;
 438 }
 439
 440 static void uevent_net_exit(struct net *net)
 441 {
 442         struct uevent_sock *ue_sk;
 443
 444         mutex_lock(&uevent_sock_mutex);
 445         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 446                 if (sock_net(ue_sk->sk) == net)
 447                         goto found;
 448         }
 449         mutex_unlock(&uevent_sock_mutex);
 450         return;
 451
 452 found:
 453         list_del(&ue_sk->list);
 454         mutex_unlock(&uevent_sock_mutex);
 455
 456         netlink_kernel_release(ue_sk->sk);
 457         kfree(ue_sk);
 458 }
 459
 460 static struct pernet_operations uevent_net_ops = {
 461         .init   = uevent_net_init,
 462         .exit   = uevent_net_exit,
 463 };
 464
 465 static int __init kobject_uevent_init(void)
 466 {
 467         return register_pernet_subsys(&uevent_net_ops);
 468 }
 469
 470
 471 postcore_initcall(kobject_uevent_init);
 472 #endif