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;
  92         const struct kobj_ns_type_operations *ops;
  93
  94         ops = kobj_ns_ops(kobj);
  95         if (ops) {
  96                 const void *sock_ns, *ns;
  97                 ns = kobj->ktype->namespace(kobj);
  98                 sock_ns = ops->netlink_ns(dsk);
  99                 return sock_ns != ns;
 100         }
 101
 102         return 0;
 103 }
 104 #endif
 105
 106 static int kobj_usermode_filter(struct kobject *kobj)
 107 {
 108         const struct kobj_ns_type_operations *ops;
 109
 110         ops = kobj_ns_ops(kobj);
 111         if (ops) {
 112                 const void *init_ns, *ns;
 113                 ns = kobj->ktype->namespace(kobj);
 114                 init_ns = ops->initial_ns();
 115                 return ns != init_ns;
 116         }
 117
 118         return 0;
 119 }
 120
 121 /**
 122  * kobject_uevent_env - send an uevent with environmental data
 123  *
 124  * @action: action that is happening
 125  * @kobj: struct kobject that the action is happening to
 126  * @envp_ext: pointer to environmental data
 127  *
 128  * Returns 0 if kobject_uevent_env() is completed with success or the
 129  * corresponding error when it fails.
 130  */
 131 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
 132                        char *envp_ext[])
 133 {
 134         struct kobj_uevent_env *env;
 135         const char *action_string = kobject_actions[action];
 136         const char *devpath = NULL;
 137         const char *subsystem;
 138         struct kobject *top_kobj;
 139         struct kset *kset;
 140         const struct kset_uevent_ops *uevent_ops;
 141         int i = 0;
 142         int retval = 0;
 143 #ifdef CONFIG_NET
 144         struct uevent_sock *ue_sk;
 145 #endif
 146
 147         pr_debug("kobject: '%s' (%p): %s\n",
 148                  kobject_name(kobj), kobj, __func__);
 149
 150         /* search the kset we belong to */
 151         top_kobj = kobj;
 152         while (!top_kobj->kset && top_kobj->parent)
 153                 top_kobj = top_kobj->parent;
 154
 155         if (!top_kobj->kset) {
 156                 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
 157                          "without kset!\n", kobject_name(kobj), kobj,
 158                          __func__);
 159                 return -EINVAL;
 160         }
 161
 162         kset = top_kobj->kset;
 163         uevent_ops = kset->uevent_ops;
 164
 165         /* skip the event, if uevent_suppress is set*/
 166         if (kobj->uevent_suppress) {
 167                 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
 168                                  "caused the event to drop!\n",
 169                                  kobject_name(kobj), kobj, __func__);
 170                 return 0;
 171         }
 172         /* skip the event, if the filter returns zero. */
 173         if (uevent_ops && uevent_ops->filter)
 174                 if (!uevent_ops->filter(kset, kobj)) {
 175                         pr_debug("kobject: '%s' (%p): %s: filter function "
 176                                  "caused the event to drop!\n",
 177                                  kobject_name(kobj), kobj, __func__);
 178                         return 0;
 179                 }
 180
 181         /* originating subsystem */
 182         if (uevent_ops && uevent_ops->name)
 183                 subsystem = uevent_ops->name(kset, kobj);
 184         else
 185                 subsystem = kobject_name(&kset->kobj);
 186         if (!subsystem) {
 187                 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
 188                          "event to drop!\n", kobject_name(kobj), kobj,
 189                          __func__);
 190                 return 0;
 191         }
 192
 193         /* environment buffer */
 194         env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
 195         if (!env)
 196                 return -ENOMEM;
 197
 198         /* complete object path */
 199         devpath = kobject_get_path(kobj, GFP_KERNEL);
 200         if (!devpath) {
 201                 retval = -ENOENT;
 202                 goto exit;
 203         }
 204
 205         /* default keys */
 206         retval = add_uevent_var(env, "ACTION=%s", action_string);
 207         if (retval)
 208                 goto exit;
 209         retval = add_uevent_var(env, "DEVPATH=%s", devpath);
 210         if (retval)
 211                 goto exit;
 212         retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
 213         if (retval)
 214                 goto exit;
 215
 216         /* keys passed in from the caller */
 217         if (envp_ext) {
 218                 for (i = 0; envp_ext[i]; i++) {
 219                         retval = add_uevent_var(env, "%s", envp_ext[i]);
 220                         if (retval)
 221                                 goto exit;
 222                 }
 223         }
 224
 225         /* let the kset specific function add its stuff */
 226         if (uevent_ops && uevent_ops->uevent) {
 227                 retval = uevent_ops->uevent(kset, kobj, env);
 228                 if (retval) {
 229                         pr_debug("kobject: '%s' (%p): %s: uevent() returned "
 230                                  "%d\n", kobject_name(kobj), kobj,
 231                                  __func__, retval);
 232                         goto exit;
 233                 }
 234         }
 235
 236         /*
 237          * Mark "add" and "remove" events in the object to ensure proper
 238          * events to userspace during automatic cleanup. If the object did
 239          * send an "add" event, "remove" will automatically generated by
 240          * the core, if not already done by the caller.
 241          */
 242         if (action == KOBJ_ADD)
 243                 kobj->state_add_uevent_sent = 1;
 244         else if (action == KOBJ_REMOVE)
 245                 kobj->state_remove_uevent_sent = 1;
 246
 247         mutex_lock(&uevent_sock_mutex);
 248         /* we will send an event, so request a new sequence number */
 249         retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum);
 250         if (retval) {
 251                 mutex_unlock(&uevent_sock_mutex);
 252                 goto exit;
 253         }
 254
 255 #if defined(CONFIG_NET)
 256         /* send netlink message */
 257         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 258                 struct sock *uevent_sock = ue_sk->sk;
 259                 struct sk_buff *skb;
 260                 size_t len;
 261
 262                 if (!netlink_has_listeners(uevent_sock, 1))
 263                         continue;
 264
 265                 /* allocate message with the maximum possible size */
 266                 len = strlen(action_string) + strlen(devpath) + 2;
 267                 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
 268                 if (skb) {
 269                         char *scratch;
 270
 271                         /* add header */
 272                         scratch = skb_put(skb, len);
 273                         sprintf(scratch, "%s@%s", action_string, devpath);
 274
 275                         /* copy keys to our continuous event payload buffer */
 276                         for (i = 0; i < env->envp_idx; i++) {
 277                                 len = strlen(env->envp[i]) + 1;
 278                                 scratch = skb_put(skb, len);
 279                                 strcpy(scratch, env->envp[i]);
 280                         }
 281
 282                         NETLINK_CB(skb).dst_group = 1;
 283                         retval = netlink_broadcast_filtered(uevent_sock, skb,
 284                                                             0, 1, GFP_KERNEL,
 285                                                             kobj_bcast_filter,
 286                                                             kobj);
 287                         /* ENOBUFS should be handled in userspace */
 288                         if (retval == -ENOBUFS || retval == -ESRCH)
 289                                 retval = 0;
 290                 } else
 291                         retval = -ENOMEM;
 292         }
 293 #endif
 294         mutex_unlock(&uevent_sock_mutex);
 295
 296         /* call uevent_helper, usually only enabled during early boot */
 297         if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
 298                 char *argv [3];
 299
 300                 argv [0] = uevent_helper;
 301                 argv [1] = (char *)subsystem;
 302                 argv [2] = NULL;
 303                 retval = add_uevent_var(env, "HOME=/");
 304                 if (retval)
 305                         goto exit;
 306                 retval = add_uevent_var(env,
 307                                         "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
 308                 if (retval)
 309                         goto exit;
 310
 311                 retval = call_usermodehelper(argv[0], argv,
 312                                              env->envp, UMH_WAIT_EXEC);
 313         }
 314
 315 exit:
 316         kfree(devpath);
 317         kfree(env);
 318         return retval;
 319 }
 320 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 321
 322 /**
 323  * kobject_uevent - notify userspace by sending an uevent
 324  *
 325  * @action: action that is happening
 326  * @kobj: struct kobject that the action is happening to
 327  *
 328  * Returns 0 if kobject_uevent() is completed with success or the
 329  * corresponding error when it fails.
 330  */
 331 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 332 {
 333         return kobject_uevent_env(kobj, action, NULL);
 334 }
 335 EXPORT_SYMBOL_GPL(kobject_uevent);
 336
 337 /**
 338  * add_uevent_var - add key value string to the environment buffer
 339  * @env: environment buffer structure
 340  * @format: printf format for the key=value pair
 341  *
 342  * Returns 0 if environment variable was added successfully or -ENOMEM
 343  * if no space was available.
 344  */
 345 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 346 {
 347         va_list args;
 348         int len;
 349
 350         if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
 351                 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
 352                 return -ENOMEM;
 353         }
 354
 355         va_start(args, format);
 356         len = vsnprintf(&env->buf[env->buflen],
 357                         sizeof(env->buf) - env->buflen,
 358                         format, args);
 359         va_end(args);
 360
 361         if (len >= (sizeof(env->buf) - env->buflen)) {
 362                 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
 363                 return -ENOMEM;
 364         }
 365
 366         env->envp[env->envp_idx++] = &env->buf[env->buflen];
 367         env->buflen += len + 1;
 368         return 0;
 369 }
 370 EXPORT_SYMBOL_GPL(add_uevent_var);
 371
 372 #if defined(CONFIG_NET)
 373 static int uevent_net_init(struct net *net)
 374 {
 375         struct uevent_sock *ue_sk;
 376
 377         ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
 378         if (!ue_sk)
 379                 return -ENOMEM;
 380
 381         ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT,
 382                                           1, NULL, NULL, THIS_MODULE);
 383         if (!ue_sk->sk) {
 384                 printk(KERN_ERR
 385                        "kobject_uevent: unable to create netlink socket!\n");
 386                 kfree(ue_sk);
 387                 return -ENODEV;
 388         }
 389         mutex_lock(&uevent_sock_mutex);
 390         list_add_tail(&ue_sk->list, &uevent_sock_list);
 391         mutex_unlock(&uevent_sock_mutex);
 392         return 0;
 393 }
 394
 395 static void uevent_net_exit(struct net *net)
 396 {
 397         struct uevent_sock *ue_sk;
 398
 399         mutex_lock(&uevent_sock_mutex);
 400         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 401                 if (sock_net(ue_sk->sk) == net)
 402                         goto found;
 403         }
 404         mutex_unlock(&uevent_sock_mutex);
 405         return;
 406
 407 found:
 408         list_del(&ue_sk->list);
 409         mutex_unlock(&uevent_sock_mutex);
 410
 411         netlink_kernel_release(ue_sk->sk);
 412         kfree(ue_sk);
 413 }
 414
 415 static struct pernet_operations uevent_net_ops = {
 416         .init   = uevent_net_init,
 417         .exit   = uevent_net_exit,
 418 };
 419
 420 static int __init kobject_uevent_init(void)
 421 {
 422         netlink_set_nonroot(NETLINK_KOBJECT_UEVENT, NL_NONROOT_RECV);
 423         return register_pernet_subsys(&uevent_net_ops);
 424 }
 425
 426
 427 postcore_initcall(kobject_uevent_init);
 428 #endif