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
  22 #include <linux/socket.h>
  23 #include <linux/skbuff.h>
  24 #include <linux/netlink.h>
  25 #include <net/sock.h>
  26
  27
  28 u64 uevent_seqnum;
  29 char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
  30 static DEFINE_SPINLOCK(sequence_lock);
  31 #if defined(CONFIG_NET)
  32 static struct sock *uevent_sock;
  33 #endif
  34
  35 /* the strings here must match the enum in include/linux/kobject.h */
  36 static const char *kobject_actions[] = {
  37         [KOBJ_ADD] =            "add",
  38         [KOBJ_REMOVE] =         "remove",
  39         [KOBJ_CHANGE] =         "change",
  40         [KOBJ_MOVE] =           "move",
  41         [KOBJ_ONLINE] =         "online",
  42         [KOBJ_OFFLINE] =        "offline",
  43 };
  44
  45 /**
  46  * kobject_action_type - translate action string to numeric type
  47  *
  48  * @buf: buffer containing the action string, newline is ignored
  49  * @len: length of buffer
  50  * @type: pointer to the location to store the action type
  51  *
  52  * Returns 0 if the action string was recognized.
  53  */
  54 int kobject_action_type(const char *buf, size_t count,
  55                         enum kobject_action *type)
  56 {
  57         enum kobject_action action;
  58         int ret = -EINVAL;
  59
  60         if (count && (buf[count-1] == '\n' || buf[count-1] == '\0'))
  61                 count--;
  62
  63         if (!count)
  64                 goto out;
  65
  66         for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
  67                 if (strncmp(kobject_actions[action], buf, count) != 0)
  68                         continue;
  69                 if (kobject_actions[action][count] != '\0')
  70                         continue;
  71                 *type = action;
  72                 ret = 0;
  73                 break;
  74         }
  75 out:
  76         return ret;
  77 }
  78
  79 /**
  80  * kobject_uevent_env - send an uevent with environmental data
  81  *
  82  * @action: action that is happening
  83  * @kobj: struct kobject that the action is happening to
  84  * @envp_ext: pointer to environmental data
  85  *
  86  * Returns 0 if kobject_uevent() is completed with success or the
  87  * corresponding error when it fails.
  88  */
  89 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
  90                        char *envp_ext[])
  91 {
  92         struct kobj_uevent_env *env;
  93         const char *action_string = kobject_actions[action];
  94         const char *devpath = NULL;
  95         const char *subsystem;
  96         struct kobject *top_kobj;
  97         struct kset *kset;
  98         struct kset_uevent_ops *uevent_ops;
  99         u64 seq;
 100         int i = 0;
 101         int retval = 0;
 102
 103         pr_debug("kobject: '%s' (%p): %s\n",
 104                  kobject_name(kobj), kobj, __func__);
 105
 106         /* search the kset we belong to */
 107         top_kobj = kobj;
 108         while (!top_kobj->kset && top_kobj->parent)
 109                 top_kobj = top_kobj->parent;
 110
 111         if (!top_kobj->kset) {
 112                 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
 113                          "without kset!\n", kobject_name(kobj), kobj,
 114                          __func__);
 115                 return -EINVAL;
 116         }
 117
 118         kset = top_kobj->kset;
 119         uevent_ops = kset->uevent_ops;
 120
 121         /* skip the event, if the filter returns zero. */
 122         if (uevent_ops && uevent_ops->filter)
 123                 if (!uevent_ops->filter(kset, kobj)) {
 124                         pr_debug("kobject: '%s' (%p): %s: filter function "
 125                                  "caused the event to drop!\n",
 126                                  kobject_name(kobj), kobj, __func__);
 127                         return 0;
 128                 }
 129
 130         /* originating subsystem */
 131         if (uevent_ops && uevent_ops->name)
 132                 subsystem = uevent_ops->name(kset, kobj);
 133         else
 134                 subsystem = kobject_name(&kset->kobj);
 135         if (!subsystem) {
 136                 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
 137                          "event to drop!\n", kobject_name(kobj), kobj,
 138                          __func__);
 139                 return 0;
 140         }
 141
 142         /* environment buffer */
 143         env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
 144         if (!env)
 145                 return -ENOMEM;
 146
 147         /* complete object path */
 148         devpath = kobject_get_path(kobj, GFP_KERNEL);
 149         if (!devpath) {
 150                 retval = -ENOENT;
 151                 goto exit;
 152         }
 153
 154         /* default keys */
 155         retval = add_uevent_var(env, "ACTION=%s", action_string);
 156         if (retval)
 157                 goto exit;
 158         retval = add_uevent_var(env, "DEVPATH=%s", devpath);
 159         if (retval)
 160                 goto exit;
 161         retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
 162         if (retval)
 163                 goto exit;
 164
 165         /* keys passed in from the caller */
 166         if (envp_ext) {
 167                 for (i = 0; envp_ext[i]; i++) {
 168                         retval = add_uevent_var(env, "%s", envp_ext[i]);
 169                         if (retval)
 170                                 goto exit;
 171                 }
 172         }
 173
 174         /* let the kset specific function add its stuff */
 175         if (uevent_ops && uevent_ops->uevent) {
 176                 retval = uevent_ops->uevent(kset, kobj, env);
 177                 if (retval) {
 178                         pr_debug("kobject: '%s' (%p): %s: uevent() returned "
 179                                  "%d\n", kobject_name(kobj), kobj,
 180                                  __func__, retval);
 181                         goto exit;
 182                 }
 183         }
 184
 185         /*
 186          * Mark "add" and "remove" events in the object to ensure proper
 187          * events to userspace during automatic cleanup. If the object did
 188          * send an "add" event, "remove" will automatically generated by
 189          * the core, if not already done by the caller.
 190          */
 191         if (action == KOBJ_ADD)
 192                 kobj->state_add_uevent_sent = 1;
 193         else if (action == KOBJ_REMOVE)
 194                 kobj->state_remove_uevent_sent = 1;
 195
 196         /* we will send an event, so request a new sequence number */
 197         spin_lock(&sequence_lock);
 198         seq = ++uevent_seqnum;
 199         spin_unlock(&sequence_lock);
 200         retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)seq);
 201         if (retval)
 202                 goto exit;
 203
 204 #if defined(CONFIG_NET)
 205         /* send netlink message */
 206         if (uevent_sock) {
 207                 struct sk_buff *skb;
 208                 size_t len;
 209
 210                 /* allocate message with the maximum possible size */
 211                 len = strlen(action_string) + strlen(devpath) + 2;
 212                 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
 213                 if (skb) {
 214                         char *scratch;
 215
 216                         /* add header */
 217                         scratch = skb_put(skb, len);
 218                         sprintf(scratch, "%s@%s", action_string, devpath);
 219
 220                         /* copy keys to our continuous event payload buffer */
 221                         for (i = 0; i < env->envp_idx; i++) {
 222                                 len = strlen(env->envp[i]) + 1;
 223                                 scratch = skb_put(skb, len);
 224                                 strcpy(scratch, env->envp[i]);
 225                         }
 226
 227                         NETLINK_CB(skb).dst_group = 1;
 228                         retval = netlink_broadcast(uevent_sock, skb, 0, 1,
 229                                                    GFP_KERNEL);
 230                         /* ENOBUFS should be handled in userspace */
 231                         if (retval == -ENOBUFS)
 232                                 retval = 0;
 233                 } else
 234                         retval = -ENOMEM;
 235         }
 236 #endif
 237
 238         /* call uevent_helper, usually only enabled during early boot */
 239         if (uevent_helper[0]) {
 240                 char *argv [3];
 241
 242                 argv [0] = uevent_helper;
 243                 argv [1] = (char *)subsystem;
 244                 argv [2] = NULL;
 245                 retval = add_uevent_var(env, "HOME=/");
 246                 if (retval)
 247                         goto exit;
 248                 retval = add_uevent_var(env,
 249                                         "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
 250                 if (retval)
 251                         goto exit;
 252
 253                 retval = call_usermodehelper(argv[0], argv,
 254                                              env->envp, UMH_WAIT_EXEC);
 255         }
 256
 257 exit:
 258         kfree(devpath);
 259         kfree(env);
 260         return retval;
 261 }
 262 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 263
 264 /**
 265  * kobject_uevent - notify userspace by ending an uevent
 266  *
 267  * @action: action that is happening
 268  * @kobj: struct kobject that the action is happening to
 269  *
 270  * Returns 0 if kobject_uevent() is completed with success or the
 271  * corresponding error when it fails.
 272  */
 273 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 274 {
 275         return kobject_uevent_env(kobj, action, NULL);
 276 }
 277 EXPORT_SYMBOL_GPL(kobject_uevent);
 278
 279 /**
 280  * add_uevent_var - add key value string to the environment buffer
 281  * @env: environment buffer structure
 282  * @format: printf format for the key=value pair
 283  *
 284  * Returns 0 if environment variable was added successfully or -ENOMEM
 285  * if no space was available.
 286  */
 287 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 288 {
 289         va_list args;
 290         int len;
 291
 292         if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
 293                 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
 294                 return -ENOMEM;
 295         }
 296
 297         va_start(args, format);
 298         len = vsnprintf(&env->buf[env->buflen],
 299                         sizeof(env->buf) - env->buflen,
 300                         format, args);
 301         va_end(args);
 302
 303         if (len >= (sizeof(env->buf) - env->buflen)) {
 304                 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
 305                 return -ENOMEM;
 306         }
 307
 308         env->envp[env->envp_idx++] = &env->buf[env->buflen];
 309         env->buflen += len + 1;
 310         return 0;
 311 }
 312 EXPORT_SYMBOL_GPL(add_uevent_var);
 313
 314 #if defined(CONFIG_NET)
 315 static int __init kobject_uevent_init(void)
 316 {
 317         uevent_sock = netlink_kernel_create(&init_net, NETLINK_KOBJECT_UEVENT,
 318                                             1, NULL, NULL, THIS_MODULE);
 319         if (!uevent_sock) {
 320                 printk(KERN_ERR
 321                        "kobject_uevent: unable to create netlink socket!\n");
 322                 return -ENODEV;
 323         }
 324
 325         return 0;
 326 }
 327
 328 postcore_initcall(kobject_uevent_init);
 329 #endif