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