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
  28
  29 u64 uevent_seqnum;
  30 char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
  31 static DEFINE_SPINLOCK(sequence_lock);
  32 #if defined(CONFIG_NET)
  33 static struct sock *uevent_sock;
  34 #endif
  35
  36 /* the strings here must match the enum in include/linux/kobject.h */
  37 static const char *kobject_actions[] = {
  38         [KOBJ_ADD] =            "add",
  39         [KOBJ_REMOVE] =         "remove",
  40         [KOBJ_CHANGE] =         "change",
  41         [KOBJ_MOVE] =           "move",
  42         [KOBJ_ONLINE] =         "online",
  43         [KOBJ_OFFLINE] =        "offline",
  44 };
  45
  46 /**
  47  * kobject_action_type - translate action string to numeric type
  48  *
  49  * @buf: buffer containing the action string, newline is ignored
  50  * @len: length of buffer
  51  * @type: pointer to the location to store the action type
  52  *
  53  * Returns 0 if the action string was recognized.
  54  */
  55 int kobject_action_type(const char *buf, size_t count,
  56                         enum kobject_action *type)
  57 {
  58         enum kobject_action action;
  59         int ret = -EINVAL;
  60
  61         if (count && (buf[count-1] == '\n' || buf[count-1] == '\0'))
  62                 count--;
  63
  64         if (!count)
  65                 goto out;
  66
  67         for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
  68                 if (strncmp(kobject_actions[action], buf, count) != 0)
  69                         continue;
  70                 if (kobject_actions[action][count] != '\0')
  71                         continue;
  72                 *type = action;
  73                 ret = 0;
  74                 break;
  75         }
  76 out:
  77         return ret;
  78 }
  79
  80 /**
  81  * kobject_uevent_env - send an uevent with environmental data
  82  *
  83  * @action: action that is happening
  84  * @kobj: struct kobject that the action is happening to
  85  * @envp_ext: pointer to environmental data
  86  *
  87  * Returns 0 if kobject_uevent() is completed with success or the
  88  * corresponding error when it fails.
  89  */
  90 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
  91                        char *envp_ext[])
  92 {
  93         struct kobj_uevent_env *env;
  94         const char *action_string = kobject_actions[action];
  95         const char *devpath = NULL;
  96         const char *subsystem;
  97         struct kobject *top_kobj;
  98         struct kset *kset;
  99         const struct kset_uevent_ops *uevent_ops;
 100         u64 seq;
 101         int i = 0;
 102         int retval = 0;
 103
 104         pr_debug("kobject: '%s' (%p): %s\n",
 105                  kobject_name(kobj), kobj, __func__);
 106
 107         /* search the kset we belong to */
 108         top_kobj = kobj;
 109         while (!top_kobj->kset && top_kobj->parent)
 110                 top_kobj = top_kobj->parent;
 111
 112         if (!top_kobj->kset) {
 113                 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
 114                          "without kset!\n", kobject_name(kobj), kobj,
 115                          __func__);
 116                 return -EINVAL;
 117         }
 118
 119         kset = top_kobj->kset;
 120         uevent_ops = kset->uevent_ops;
 121
 122         /* skip the event, if uevent_suppress is set*/
 123         if (kobj->uevent_suppress) {
 124                 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
 125                                  "caused the event to drop!\n",
 126                                  kobject_name(kobj), kobj, __func__);
 127                 return 0;
 128         }
 129         /* skip the event, if the filter returns zero. */
 130         if (uevent_ops && uevent_ops->filter)
 131                 if (!uevent_ops->filter(kset, kobj)) {
 132                         pr_debug("kobject: '%s' (%p): %s: filter function "
 133                                  "caused the event to drop!\n",
 134                                  kobject_name(kobj), kobj, __func__);
 135                         return 0;
 136                 }
 137
 138         /* originating subsystem */
 139         if (uevent_ops && uevent_ops->name)
 140                 subsystem = uevent_ops->name(kset, kobj);
 141         else
 142                 subsystem = kobject_name(&kset->kobj);
 143         if (!subsystem) {
 144                 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
 145                          "event to drop!\n", kobject_name(kobj), kobj,
 146                          __func__);
 147                 return 0;
 148         }
 149
 150         /* environment buffer */
 151         env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
 152         if (!env)
 153                 return -ENOMEM;
 154
 155         /* complete object path */
 156         devpath = kobject_get_path(kobj, GFP_KERNEL);
 157         if (!devpath) {
 158                 retval = -ENOENT;
 159                 goto exit;
 160         }
 161
 162         /* default keys */
 163         retval = add_uevent_var(env, "ACTION=%s", action_string);
 164         if (retval)
 165                 goto exit;
 166         retval = add_uevent_var(env, "DEVPATH=%s", devpath);
 167         if (retval)
 168                 goto exit;
 169         retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
 170         if (retval)
 171                 goto exit;
 172
 173         /* keys passed in from the caller */
 174         if (envp_ext) {
 175                 for (i = 0; envp_ext[i]; i++) {
 176                         retval = add_uevent_var(env, "%s", envp_ext[i]);
 177                         if (retval)
 178                                 goto exit;
 179                 }
 180         }
 181
 182         /* let the kset specific function add its stuff */
 183         if (uevent_ops && uevent_ops->uevent) {
 184                 retval = uevent_ops->uevent(kset, kobj, env);
 185                 if (retval) {
 186                         pr_debug("kobject: '%s' (%p): %s: uevent() returned "
 187                                  "%d\n", kobject_name(kobj), kobj,
 188                                  __func__, retval);
 189                         goto exit;
 190                 }
 191         }
 192
 193         /*
 194          * Mark "add" and "remove" events in the object to ensure proper
 195          * events to userspace during automatic cleanup. If the object did
 196          * send an "add" event, "remove" will automatically generated by
 197          * the core, if not already done by the caller.
 198          */
 199         if (action == KOBJ_ADD)
 200                 kobj->state_add_uevent_sent = 1;
 201         else if (action == KOBJ_REMOVE)
 202                 kobj->state_remove_uevent_sent = 1;
 203
 204         /* we will send an event, so request a new sequence number */
 205         spin_lock(&sequence_lock);
 206         seq = ++uevent_seqnum;
 207         spin_unlock(&sequence_lock);
 208         retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)seq);
 209         if (retval)
 210                 goto exit;
 211
 212 #if defined(CONFIG_NET)
 213         /* send netlink message */
 214         if (uevent_sock) {
 215                 struct sk_buff *skb;
 216                 size_t len;
 217
 218                 /* allocate message with the maximum possible size */
 219                 len = strlen(action_string) + strlen(devpath) + 2;
 220                 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
 221                 if (skb) {
 222                         char *scratch;
 223
 224                         /* add header */
 225                         scratch = skb_put(skb, len);
 226                         sprintf(scratch, "%s@%s", action_string, devpath);
 227
 228                         /* copy keys to our continuous event payload buffer */
 229                         for (i = 0; i < env->envp_idx; i++) {
 230                                 len = strlen(env->envp[i]) + 1;
 231                                 scratch = skb_put(skb, len);
 232                                 strcpy(scratch, env->envp[i]);
 233                         }
 234
 235                         NETLINK_CB(skb).dst_group = 1;
 236                         retval = netlink_broadcast(uevent_sock, skb, 0, 1,
 237                                                    GFP_KERNEL);
 238                         /* ENOBUFS should be handled in userspace */
 239                         if (retval == -ENOBUFS)
 240                                 retval = 0;
 241                 } else
 242                         retval = -ENOMEM;
 243         }
 244 #endif
 245
 246         /* call uevent_helper, usually only enabled during early boot */
 247         if (uevent_helper[0]) {
 248                 char *argv [3];
 249
 250                 argv [0] = uevent_helper;
 251                 argv [1] = (char *)subsystem;
 252                 argv [2] = NULL;
 253                 retval = add_uevent_var(env, "HOME=/");
 254                 if (retval)
 255                         goto exit;
 256                 retval = add_uevent_var(env,
 257                                         "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
 258                 if (retval)
 259                         goto exit;
 260
 261                 retval = call_usermodehelper(argv[0], argv,
 262                                              env->envp, UMH_WAIT_EXEC);
 263         }
 264
 265 exit:
 266         kfree(devpath);
 267         kfree(env);
 268         return retval;
 269 }
 270 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 271
 272 /**
 273  * kobject_uevent - notify userspace by ending an uevent
 274  *
 275  * @action: action that is happening
 276  * @kobj: struct kobject that the action is happening to
 277  *
 278  * Returns 0 if kobject_uevent() is completed with success or the
 279  * corresponding error when it fails.
 280  */
 281 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 282 {
 283         return kobject_uevent_env(kobj, action, NULL);
 284 }
 285 EXPORT_SYMBOL_GPL(kobject_uevent);
 286
 287 /**
 288  * add_uevent_var - add key value string to the environment buffer
 289  * @env: environment buffer structure
 290  * @format: printf format for the key=value pair
 291  *
 292  * Returns 0 if environment variable was added successfully or -ENOMEM
 293  * if no space was available.
 294  */
 295 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 296 {
 297         va_list args;
 298         int len;
 299
 300         if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
 301                 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
 302                 return -ENOMEM;
 303         }
 304
 305         va_start(args, format);
 306         len = vsnprintf(&env->buf[env->buflen],
 307                         sizeof(env->buf) - env->buflen,
 308                         format, args);
 309         va_end(args);
 310
 311         if (len >= (sizeof(env->buf) - env->buflen)) {
 312                 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
 313                 return -ENOMEM;
 314         }
 315
 316         env->envp[env->envp_idx++] = &env->buf[env->buflen];
 317         env->buflen += len + 1;
 318         return 0;
 319 }
 320 EXPORT_SYMBOL_GPL(add_uevent_var);
 321
 322 #if defined(CONFIG_NET)
 323 static int __init kobject_uevent_init(void)
 324 {
 325         uevent_sock = netlink_kernel_create(&init_net, NETLINK_KOBJECT_UEVENT,
 326                                             1, NULL, NULL, THIS_MODULE);
 327         if (!uevent_sock) {
 328                 printk(KERN_ERR
 329                        "kobject_uevent: unable to create netlink socket!\n");
 330                 return -ENODEV;
 331         }
 332         netlink_set_nonroot(NETLINK_KOBJECT_UEVENT, NL_NONROOT_RECV);
 333         return 0;
 334 }
 335
 336 postcore_initcall(kobject_uevent_init);
 337 #endif