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