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 static DEFINE_SPINLOCK(sequence_lock);
  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 static DEFINE_MUTEX(uevent_sock_mutex);
  40 #endif
  41
  42 /* the strings here must match the enum in include/linux/kobject.h */
  43 static const char *kobject_actions[] = {
  44         [KOBJ_ADD] =            "add",
  45         [KOBJ_REMOVE] =         "remove",
  46         [KOBJ_CHANGE] =         "change",
  47         [KOBJ_MOVE] =           "move",
  48         [KOBJ_ONLINE] =         "online",
  49         [KOBJ_OFFLINE] =        "offline",
  50 };
  51
  52 /**
  53  * kobject_action_type - translate action string to numeric type
  54  *
  55  * @buf: buffer containing the action string, newline is ignored
  56  * @len: length of buffer
  57  * @type: pointer to the location to store the action type
  58  *
  59  * Returns 0 if the action string was recognized.
  60  */
  61 int kobject_action_type(const char *buf, size_t count,
  62                         enum kobject_action *type)
  63 {
  64         enum kobject_action action;
  65         int ret = -EINVAL;
  66
  67         if (count && (buf[count-1] == '\n' || buf[count-1] == '\0'))
  68                 count--;
  69
  70         if (!count)
  71                 goto out;
  72
  73         for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
  74                 if (strncmp(kobject_actions[action], buf, count) != 0)
  75                         continue;
  76                 if (kobject_actions[action][count] != '\0')
  77                         continue;
  78                 *type = action;
  79                 ret = 0;
  80                 break;
  81         }
  82 out:
  83         return ret;
  84 }
  85
  86 static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data)
  87 {
  88         struct kobject *kobj = data;
  89         const struct kobj_ns_type_operations *ops;
  90
  91         ops = kobj_ns_ops(kobj);
  92         if (ops) {
  93                 const void *sock_ns, *ns;
  94                 ns = kobj->ktype->namespace(kobj);
  95                 sock_ns = ops->netlink_ns(dsk);
  96                 return sock_ns != ns;
  97         }
  98
  99         return 0;
 100 }
 101
 102 static int kobj_usermode_filter(struct kobject *kobj)
 103 {
 104         const struct kobj_ns_type_operations *ops;
 105
 106         ops = kobj_ns_ops(kobj);
 107         if (ops) {
 108                 const void *init_ns, *ns;
 109                 ns = kobj->ktype->namespace(kobj);
 110                 init_ns = ops->initial_ns();
 111                 return ns != init_ns;
 112         }
 113
 114         return 0;
 115 }
 116
 117 /**
 118  * kobject_uevent_env - send an uevent with environmental data
 119  *
 120  * @action: action that is happening
 121  * @kobj: struct kobject that the action is happening to
 122  * @envp_ext: pointer to environmental data
 123  *
 124  * Returns 0 if kobject_uevent() is completed with success or the
 125  * corresponding error when it fails.
 126  */
 127 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
 128                        char *envp_ext[])
 129 {
 130         struct kobj_uevent_env *env;
 131         const char *action_string = kobject_actions[action];
 132         const char *devpath = NULL;
 133         const char *subsystem;
 134         struct kobject *top_kobj;
 135         struct kset *kset;
 136         const struct kset_uevent_ops *uevent_ops;
 137         u64 seq;
 138         int i = 0;
 139         int retval = 0;
 140 #ifdef CONFIG_NET
 141         struct uevent_sock *ue_sk;
 142 #endif
 143
 144         pr_debug("kobject: '%s' (%p): %s\n",
 145                  kobject_name(kobj), kobj, __func__);
 146
 147         /* search the kset we belong to */
 148         top_kobj = kobj;
 149         while (!top_kobj->kset && top_kobj->parent)
 150                 top_kobj = top_kobj->parent;
 151
 152         if (!top_kobj->kset) {
 153                 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
 154                          "without kset!\n", kobject_name(kobj), kobj,
 155                          __func__);
 156                 return -EINVAL;
 157         }
 158
 159         kset = top_kobj->kset;
 160         uevent_ops = kset->uevent_ops;
 161
 162         /* skip the event, if uevent_suppress is set*/
 163         if (kobj->uevent_suppress) {
 164                 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
 165                                  "caused the event to drop!\n",
 166                                  kobject_name(kobj), kobj, __func__);
 167                 return 0;
 168         }
 169         /* skip the event, if the filter returns zero. */
 170         if (uevent_ops && uevent_ops->filter)
 171                 if (!uevent_ops->filter(kset, kobj)) {
 172                         pr_debug("kobject: '%s' (%p): %s: filter function "
 173                                  "caused the event to drop!\n",
 174                                  kobject_name(kobj), kobj, __func__);
 175                         return 0;
 176                 }
 177
 178         /* originating subsystem */
 179         if (uevent_ops && uevent_ops->name)
 180                 subsystem = uevent_ops->name(kset, kobj);
 181         else
 182                 subsystem = kobject_name(&kset->kobj);
 183         if (!subsystem) {
 184                 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
 185                          "event to drop!\n", kobject_name(kobj), kobj,
 186                          __func__);
 187                 return 0;
 188         }
 189
 190         /* environment buffer */
 191         env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
 192         if (!env)
 193                 return -ENOMEM;
 194
 195         /* complete object path */
 196         devpath = kobject_get_path(kobj, GFP_KERNEL);
 197         if (!devpath) {
 198                 retval = -ENOENT;
 199                 goto exit;
 200         }
 201
 202         /* default keys */
 203         retval = add_uevent_var(env, "ACTION=%s", action_string);
 204         if (retval)
 205                 goto exit;
 206         retval = add_uevent_var(env, "DEVPATH=%s", devpath);
 207         if (retval)
 208                 goto exit;
 209         retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
 210         if (retval)
 211                 goto exit;
 212
 213         /* keys passed in from the caller */
 214         if (envp_ext) {
 215                 for (i = 0; envp_ext[i]; i++) {
 216                         retval = add_uevent_var(env, "%s", envp_ext[i]);
 217                         if (retval)
 218                                 goto exit;
 219                 }
 220         }
 221
 222         /* let the kset specific function add its stuff */
 223         if (uevent_ops && uevent_ops->uevent) {
 224                 retval = uevent_ops->uevent(kset, kobj, env);
 225                 if (retval) {
 226                         pr_debug("kobject: '%s' (%p): %s: uevent() returned "
 227                                  "%d\n", kobject_name(kobj), kobj,
 228                                  __func__, retval);
 229                         goto exit;
 230                 }
 231         }
 232
 233         /*
 234          * Mark "add" and "remove" events in the object to ensure proper
 235          * events to userspace during automatic cleanup. If the object did
 236          * send an "add" event, "remove" will automatically generated by
 237          * the core, if not already done by the caller.
 238          */
 239         if (action == KOBJ_ADD)
 240                 kobj->state_add_uevent_sent = 1;
 241         else if (action == KOBJ_REMOVE)
 242                 kobj->state_remove_uevent_sent = 1;
 243
 244         /* we will send an event, so request a new sequence number */
 245         spin_lock(&sequence_lock);
 246         seq = ++uevent_seqnum;
 247         spin_unlock(&sequence_lock);
 248         retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)seq);
 249         if (retval)
 250                 goto exit;
 251
 252 #if defined(CONFIG_NET)
 253         /* send netlink message */
 254         mutex_lock(&uevent_sock_mutex);
 255         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 256                 struct sock *uevent_sock = ue_sk->sk;
 257                 struct sk_buff *skb;
 258                 size_t len;
 259
 260                 /* allocate message with the maximum possible size */
 261                 len = strlen(action_string) + strlen(devpath) + 2;
 262                 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
 263                 if (skb) {
 264                         char *scratch;
 265
 266                         /* add header */
 267                         scratch = skb_put(skb, len);
 268                         sprintf(scratch, "%s@%s", action_string, devpath);
 269
 270                         /* copy keys to our continuous event payload buffer */
 271                         for (i = 0; i < env->envp_idx; i++) {
 272                                 len = strlen(env->envp[i]) + 1;
 273                                 scratch = skb_put(skb, len);
 274                                 strcpy(scratch, env->envp[i]);
 275                         }
 276
 277                         NETLINK_CB(skb).dst_group = 1;
 278                         retval = netlink_broadcast_filtered(uevent_sock, skb,
 279                                                             0, 1, GFP_KERNEL,
 280                                                             kobj_bcast_filter,
 281                                                             kobj);
 282                         /* ENOBUFS should be handled in userspace */
 283                         if (retval == -ENOBUFS)
 284                                 retval = 0;
 285                 } else
 286                         retval = -ENOMEM;
 287         }
 288         mutex_unlock(&uevent_sock_mutex);
 289 #endif
 290
 291         /* call uevent_helper, usually only enabled during early boot */
 292         if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
 293                 char *argv [3];
 294
 295                 argv [0] = uevent_helper;
 296                 argv [1] = (char *)subsystem;
 297                 argv [2] = NULL;
 298                 retval = add_uevent_var(env, "HOME=/");
 299                 if (retval)
 300                         goto exit;
 301                 retval = add_uevent_var(env,
 302                                         "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
 303                 if (retval)
 304                         goto exit;
 305
 306                 retval = call_usermodehelper(argv[0], argv,
 307                                              env->envp, UMH_WAIT_EXEC);
 308         }
 309
 310 exit:
 311         kfree(devpath);
 312         kfree(env);
 313         return retval;
 314 }
 315 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 316
 317 /**
 318  * kobject_uevent - notify userspace by ending an uevent
 319  *
 320  * @action: action that is happening
 321  * @kobj: struct kobject that the action is happening to
 322  *
 323  * Returns 0 if kobject_uevent() is completed with success or the
 324  * corresponding error when it fails.
 325  */
 326 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 327 {
 328         return kobject_uevent_env(kobj, action, NULL);
 329 }
 330 EXPORT_SYMBOL_GPL(kobject_uevent);
 331
 332 /**
 333  * add_uevent_var - add key value string to the environment buffer
 334  * @env: environment buffer structure
 335  * @format: printf format for the key=value pair
 336  *
 337  * Returns 0 if environment variable was added successfully or -ENOMEM
 338  * if no space was available.
 339  */
 340 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 341 {
 342         va_list args;
 343         int len;
 344
 345         if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
 346                 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
 347                 return -ENOMEM;
 348         }
 349
 350         va_start(args, format);
 351         len = vsnprintf(&env->buf[env->buflen],
 352                         sizeof(env->buf) - env->buflen,
 353                         format, args);
 354         va_end(args);
 355
 356         if (len >= (sizeof(env->buf) - env->buflen)) {
 357                 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
 358                 return -ENOMEM;
 359         }
 360
 361         env->envp[env->envp_idx++] = &env->buf[env->buflen];
 362         env->buflen += len + 1;
 363         return 0;
 364 }
 365 EXPORT_SYMBOL_GPL(add_uevent_var);
 366
 367 #if defined(CONFIG_NET)
 368 static int uevent_net_init(struct net *net)
 369 {
 370         struct uevent_sock *ue_sk;
 371
 372         ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
 373         if (!ue_sk)
 374                 return -ENOMEM;
 375
 376         ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT,
 377                                           1, NULL, NULL, THIS_MODULE);
 378         if (!ue_sk->sk) {
 379                 printk(KERN_ERR
 380                        "kobject_uevent: unable to create netlink socket!\n");
 381                 return -ENODEV;
 382         }
 383         mutex_lock(&uevent_sock_mutex);
 384         list_add_tail(&ue_sk->list, &uevent_sock_list);
 385         mutex_unlock(&uevent_sock_mutex);
 386         return 0;
 387 }
 388
 389 static void uevent_net_exit(struct net *net)
 390 {
 391         struct uevent_sock *ue_sk;
 392
 393         mutex_lock(&uevent_sock_mutex);
 394         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 395                 if (sock_net(ue_sk->sk) == net)
 396                         goto found;
 397         }
 398         mutex_unlock(&uevent_sock_mutex);
 399         return;
 400
 401 found:
 402         list_del(&ue_sk->list);
 403         mutex_unlock(&uevent_sock_mutex);
 404
 405         netlink_kernel_release(ue_sk->sk);
 406         kfree(ue_sk);
 407 }
 408
 409 static struct pernet_operations uevent_net_ops = {
 410         .init   = uevent_net_init,
 411         .exit   = uevent_net_exit,
 412 };
 413
 414 static int __init kobject_uevent_init(void)
 415 {
 416         netlink_set_nonroot(NETLINK_KOBJECT_UEVENT, NL_NONROOT_RECV);
 417         return register_pernet_subsys(&uevent_net_ops);
 418 }
 419
 420
 421 postcore_initcall(kobject_uevent_init);
 422 #endif