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