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')
  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("%s\n", __FUNCTION__);
 102
 103         /* search the kset we belong to */
 104         top_kobj = kobj;
 105         while (!top_kobj->kset && top_kobj->parent)
 106                 top_kobj = top_kobj->parent;
 107
 108         if (!top_kobj->kset) {
 109                 pr_debug("kobject attempted to send uevent without kset!\n");
 110                 return -EINVAL;
 111         }
 112
 113         kset = top_kobj->kset;
 114         uevent_ops = kset->uevent_ops;
 115
 116         /* skip the event, if the filter returns zero. */
 117         if (uevent_ops && uevent_ops->filter)
 118                 if (!uevent_ops->filter(kset, kobj)) {
 119                         pr_debug("kobject filter function caused the event to drop!\n");
 120                         return 0;
 121                 }
 122
 123         /* originating subsystem */
 124         if (uevent_ops && uevent_ops->name)
 125                 subsystem = uevent_ops->name(kset, kobj);
 126         else
 127                 subsystem = kobject_name(&kset->kobj);
 128         if (!subsystem) {
 129                 pr_debug("unset subsystem caused the event to drop!\n");
 130                 return 0;
 131         }
 132
 133         /* environment buffer */
 134         env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
 135         if (!env)
 136                 return -ENOMEM;
 137
 138         /* complete object path */
 139         devpath = kobject_get_path(kobj, GFP_KERNEL);
 140         if (!devpath) {
 141                 retval = -ENOENT;
 142                 goto exit;
 143         }
 144
 145         /* default keys */
 146         retval = add_uevent_var(env, "ACTION=%s", action_string);
 147         if (retval)
 148                 goto exit;
 149         retval = add_uevent_var(env, "DEVPATH=%s", devpath);
 150         if (retval)
 151                 goto exit;
 152         retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
 153         if (retval)
 154                 goto exit;
 155
 156         /* keys passed in from the caller */
 157         if (envp_ext) {
 158                 for (i = 0; envp_ext[i]; i++) {
 159                         retval = add_uevent_var(env, envp_ext[i]);
 160                         if (retval)
 161                                 goto exit;
 162                 }
 163         }
 164
 165         /* let the kset specific function add its stuff */
 166         if (uevent_ops && uevent_ops->uevent) {
 167                 retval = uevent_ops->uevent(kset, kobj, env);
 168                 if (retval) {
 169                         pr_debug ("%s - uevent() returned %d\n",
 170                                   __FUNCTION__, retval);
 171                         goto exit;
 172                 }
 173         }
 174
 175         /* we will send an event, so request a new sequence number */
 176         spin_lock(&sequence_lock);
 177         seq = ++uevent_seqnum;
 178         spin_unlock(&sequence_lock);
 179         retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)seq);
 180         if (retval)
 181                 goto exit;
 182
 183 #if defined(CONFIG_NET)
 184         /* send netlink message */
 185         if (uevent_sock) {
 186                 struct sk_buff *skb;
 187                 size_t len;
 188
 189                 /* allocate message with the maximum possible size */
 190                 len = strlen(action_string) + strlen(devpath) + 2;
 191                 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
 192                 if (skb) {
 193                         char *scratch;
 194
 195                         /* add header */
 196                         scratch = skb_put(skb, len);
 197                         sprintf(scratch, "%s@%s", action_string, devpath);
 198
 199                         /* copy keys to our continuous event payload buffer */
 200                         for (i = 0; i < env->envp_idx; i++) {
 201                                 len = strlen(env->envp[i]) + 1;
 202                                 scratch = skb_put(skb, len);
 203                                 strcpy(scratch, env->envp[i]);
 204                         }
 205
 206                         NETLINK_CB(skb).dst_group = 1;
 207                         netlink_broadcast(uevent_sock, skb, 0, 1, GFP_KERNEL);
 208                 }
 209         }
 210 #endif
 211
 212         /* call uevent_helper, usually only enabled during early boot */
 213         if (uevent_helper[0]) {
 214                 char *argv [3];
 215
 216                 argv [0] = uevent_helper;
 217                 argv [1] = (char *)subsystem;
 218                 argv [2] = NULL;
 219                 retval = add_uevent_var(env, "HOME=/");
 220                 if (retval)
 221                         goto exit;
 222                 retval = add_uevent_var(env, "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
 223                 if (retval)
 224                         goto exit;
 225
 226                 call_usermodehelper (argv[0], argv, env->envp, UMH_WAIT_EXEC);
 227         }
 228
 229 exit:
 230         kfree(devpath);
 231         kfree(env);
 232         return retval;
 233 }
 234
 235 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 236
 237 /**
 238  * kobject_uevent - notify userspace by ending an uevent
 239  *
 240  * @action: action that is happening
 241  * @kobj: struct kobject that the action is happening to
 242  *
 243  * Returns 0 if kobject_uevent() is completed with success or the
 244  * corresponding error when it fails.
 245  */
 246 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 247 {
 248         return kobject_uevent_env(kobj, action, NULL);
 249 }
 250
 251 EXPORT_SYMBOL_GPL(kobject_uevent);
 252
 253 /**
 254  * add_uevent_var - add key value string to the environment buffer
 255  * @env: environment buffer structure
 256  * @format: printf format for the key=value pair
 257  *
 258  * Returns 0 if environment variable was added successfully or -ENOMEM
 259  * if no space was available.
 260  */
 261 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 262 {
 263         va_list args;
 264         int len;
 265
 266         if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
 267                 printk(KERN_ERR "add_uevent_var: too many keys\n");
 268                 WARN_ON(1);
 269                 return -ENOMEM;
 270         }
 271
 272         va_start(args, format);
 273         len = vsnprintf(&env->buf[env->buflen],
 274                         sizeof(env->buf) - env->buflen,
 275                         format, args);
 276         va_end(args);
 277
 278         if (len >= (sizeof(env->buf) - env->buflen)) {
 279                 printk(KERN_ERR "add_uevent_var: buffer size too small\n");
 280                 WARN_ON(1);
 281                 return -ENOMEM;
 282         }
 283
 284         env->envp[env->envp_idx++] = &env->buf[env->buflen];
 285         env->buflen += len + 1;
 286         return 0;
 287 }
 288 EXPORT_SYMBOL_GPL(add_uevent_var);
 289
 290 #if defined(CONFIG_NET)
 291 static int __init kobject_uevent_init(void)
 292 {
 293         uevent_sock = netlink_kernel_create(&init_net, NETLINK_KOBJECT_UEVENT,
 294                                             1, NULL, NULL, THIS_MODULE);
 295         if (!uevent_sock) {
 296                 printk(KERN_ERR
 297                        "kobject_uevent: unable to create netlink socket!\n");
 298                 return -ENODEV;
 299         }
 300
 301         return 0;
 302 }
 303
 304 postcore_initcall(kobject_uevent_init);
 305 #endif