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