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 /**
 128  * kobject_uevent_env - send an uevent with environmental data
 129  *
 130  * @action: action that is happening
 131  * @kobj: struct kobject that the action is happening to
 132  * @envp_ext: pointer to environmental data
 133  *
 134  * Returns 0 if kobject_uevent_env() is completed with success or the
 135  * corresponding error when it fails.
 136  */
 137 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
 138                        char *envp_ext[])
 139 {
 140         struct kobj_uevent_env *env;
 141         const char *action_string = kobject_actions[action];
 142         const char *devpath = NULL;
 143         const char *subsystem;
 144         struct kobject *top_kobj;
 145         struct kset *kset;
 146         const struct kset_uevent_ops *uevent_ops;
 147         int i = 0;
 148         int retval = 0;
 149 #ifdef CONFIG_NET
 150         struct uevent_sock *ue_sk;
 151 #endif
 152
 153         pr_debug("kobject: '%s' (%p): %s\n",
 154                  kobject_name(kobj), kobj, __func__);
 155
 156         /* search the kset we belong to */
 157         top_kobj = kobj;
 158         while (!top_kobj->kset && top_kobj->parent)
 159                 top_kobj = top_kobj->parent;
 160
 161         if (!top_kobj->kset) {
 162                 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
 163                          "without kset!\n", kobject_name(kobj), kobj,
 164                          __func__);
 165                 return -EINVAL;
 166         }
 167
 168         kset = top_kobj->kset;
 169         uevent_ops = kset->uevent_ops;
 170
 171         /* skip the event, if uevent_suppress is set*/
 172         if (kobj->uevent_suppress) {
 173                 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
 174                                  "caused the event to drop!\n",
 175                                  kobject_name(kobj), kobj, __func__);
 176                 return 0;
 177         }
 178         /* skip the event, if the filter returns zero. */
 179         if (uevent_ops && uevent_ops->filter)
 180                 if (!uevent_ops->filter(kset, kobj)) {
 181                         pr_debug("kobject: '%s' (%p): %s: filter function "
 182                                  "caused the event to drop!\n",
 183                                  kobject_name(kobj), kobj, __func__);
 184                         return 0;
 185                 }
 186
 187         /* originating subsystem */
 188         if (uevent_ops && uevent_ops->name)
 189                 subsystem = uevent_ops->name(kset, kobj);
 190         else
 191                 subsystem = kobject_name(&kset->kobj);
 192         if (!subsystem) {
 193                 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
 194                          "event to drop!\n", kobject_name(kobj), kobj,
 195                          __func__);
 196                 return 0;
 197         }
 198
 199         /* environment buffer */
 200         env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
 201         if (!env)
 202                 return -ENOMEM;
 203
 204         /* complete object path */
 205         devpath = kobject_get_path(kobj, GFP_KERNEL);
 206         if (!devpath) {
 207                 retval = -ENOENT;
 208                 goto exit;
 209         }
 210
 211         /* default keys */
 212         retval = add_uevent_var(env, "ACTION=%s", action_string);
 213         if (retval)
 214                 goto exit;
 215         retval = add_uevent_var(env, "DEVPATH=%s", devpath);
 216         if (retval)
 217                 goto exit;
 218         retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
 219         if (retval)
 220                 goto exit;
 221
 222         /* keys passed in from the caller */
 223         if (envp_ext) {
 224                 for (i = 0; envp_ext[i]; i++) {
 225                         retval = add_uevent_var(env, "%s", envp_ext[i]);
 226                         if (retval)
 227                                 goto exit;
 228                 }
 229         }
 230
 231         /* let the kset specific function add its stuff */
 232         if (uevent_ops && uevent_ops->uevent) {
 233                 retval = uevent_ops->uevent(kset, kobj, env);
 234                 if (retval) {
 235                         pr_debug("kobject: '%s' (%p): %s: uevent() returned "
 236                                  "%d\n", kobject_name(kobj), kobj,
 237                                  __func__, retval);
 238                         goto exit;
 239                 }
 240         }
 241
 242         /*
 243          * Mark "add" and "remove" events in the object to ensure proper
 244          * events to userspace during automatic cleanup. If the object did
 245          * send an "add" event, "remove" will automatically generated by
 246          * the core, if not already done by the caller.
 247          */
 248         if (action == KOBJ_ADD)
 249                 kobj->state_add_uevent_sent = 1;
 250         else if (action == KOBJ_REMOVE)
 251                 kobj->state_remove_uevent_sent = 1;
 252
 253         mutex_lock(&uevent_sock_mutex);
 254         /* we will send an event, so request a new sequence number */
 255         retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum);
 256         if (retval) {
 257                 mutex_unlock(&uevent_sock_mutex);
 258                 goto exit;
 259         }
 260
 261 #if defined(CONFIG_NET)
 262         /* send netlink message */
 263         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 264                 struct sock *uevent_sock = ue_sk->sk;
 265                 struct sk_buff *skb;
 266                 size_t len;
 267
 268                 if (!netlink_has_listeners(uevent_sock, 1))
 269                         continue;
 270
 271                 /* allocate message with the maximum possible size */
 272                 len = strlen(action_string) + strlen(devpath) + 2;
 273                 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
 274                 if (skb) {
 275                         char *scratch;
 276
 277                         /* add header */
 278                         scratch = skb_put(skb, len);
 279                         sprintf(scratch, "%s@%s", action_string, devpath);
 280
 281                         /* copy keys to our continuous event payload buffer */
 282                         for (i = 0; i < env->envp_idx; i++) {
 283                                 len = strlen(env->envp[i]) + 1;
 284                                 scratch = skb_put(skb, len);
 285                                 strcpy(scratch, env->envp[i]);
 286                         }
 287
 288                         NETLINK_CB(skb).dst_group = 1;
 289                         retval = netlink_broadcast_filtered(uevent_sock, skb,
 290                                                             0, 1, GFP_KERNEL,
 291                                                             kobj_bcast_filter,
 292                                                             kobj);
 293                         /* ENOBUFS should be handled in userspace */
 294                         if (retval == -ENOBUFS || retval == -ESRCH)
 295                                 retval = 0;
 296                 } else
 297                         retval = -ENOMEM;
 298         }
 299 #endif
 300         mutex_unlock(&uevent_sock_mutex);
 301
 302         /* call uevent_helper, usually only enabled during early boot */
 303         if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
 304                 char *argv [3];
 305
 306                 argv [0] = uevent_helper;
 307                 argv [1] = (char *)subsystem;
 308                 argv [2] = NULL;
 309                 retval = add_uevent_var(env, "HOME=/");
 310                 if (retval)
 311                         goto exit;
 312                 retval = add_uevent_var(env,
 313                                         "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
 314                 if (retval)
 315                         goto exit;
 316
 317                 retval = call_usermodehelper(argv[0], argv,
 318                                              env->envp, UMH_WAIT_EXEC);
 319         }
 320
 321 exit:
 322         kfree(devpath);
 323         kfree(env);
 324         return retval;
 325 }
 326 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 327
 328 /**
 329  * kobject_uevent - notify userspace by sending an uevent
 330  *
 331  * @action: action that is happening
 332  * @kobj: struct kobject that the action is happening to
 333  *
 334  * Returns 0 if kobject_uevent() is completed with success or the
 335  * corresponding error when it fails.
 336  */
 337 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 338 {
 339         return kobject_uevent_env(kobj, action, NULL);
 340 }
 341 EXPORT_SYMBOL_GPL(kobject_uevent);
 342
 343 /**
 344  * add_uevent_var - add key value string to the environment buffer
 345  * @env: environment buffer structure
 346  * @format: printf format for the key=value pair
 347  *
 348  * Returns 0 if environment variable was added successfully or -ENOMEM
 349  * if no space was available.
 350  */
 351 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 352 {
 353         va_list args;
 354         int len;
 355
 356         if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
 357                 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
 358                 return -ENOMEM;
 359         }
 360
 361         va_start(args, format);
 362         len = vsnprintf(&env->buf[env->buflen],
 363                         sizeof(env->buf) - env->buflen,
 364                         format, args);
 365         va_end(args);
 366
 367         if (len >= (sizeof(env->buf) - env->buflen)) {
 368                 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
 369                 return -ENOMEM;
 370         }
 371
 372         env->envp[env->envp_idx++] = &env->buf[env->buflen];
 373         env->buflen += len + 1;
 374         return 0;
 375 }
 376 EXPORT_SYMBOL_GPL(add_uevent_var);
 377
 378 #if defined(CONFIG_NET)
 379 static int uevent_net_init(struct net *net)
 380 {
 381         struct uevent_sock *ue_sk;
 382         struct netlink_kernel_cfg cfg = {
 383                 .groups = 1,
 384                 .flags  = NL_CFG_F_NONROOT_RECV,
 385         };
 386
 387         ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
 388         if (!ue_sk)
 389                 return -ENOMEM;
 390
 391         ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
 392         if (!ue_sk->sk) {
 393                 printk(KERN_ERR
 394                        "kobject_uevent: unable to create netlink socket!\n");
 395                 kfree(ue_sk);
 396                 return -ENODEV;
 397         }
 398         mutex_lock(&uevent_sock_mutex);
 399         list_add_tail(&ue_sk->list, &uevent_sock_list);
 400         mutex_unlock(&uevent_sock_mutex);
 401         return 0;
 402 }
 403
 404 static void uevent_net_exit(struct net *net)
 405 {
 406         struct uevent_sock *ue_sk;
 407
 408         mutex_lock(&uevent_sock_mutex);
 409         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 410                 if (sock_net(ue_sk->sk) == net)
 411                         goto found;
 412         }
 413         mutex_unlock(&uevent_sock_mutex);
 414         return;
 415
 416 found:
 417         list_del(&ue_sk->list);
 418         mutex_unlock(&uevent_sock_mutex);
 419
 420         netlink_kernel_release(ue_sk->sk);
 421         kfree(ue_sk);
 422 }
 423
 424 static struct pernet_operations uevent_net_ops = {
 425         .init   = uevent_net_init,
 426         .exit   = uevent_net_exit,
 427 };
 428
 429 static int __init kobject_uevent_init(void)
 430 {
 431         return register_pernet_subsys(&uevent_net_ops);
 432 }
 433
 434
 435 postcore_initcall(kobject_uevent_init);
 436 #endif