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 #define BUFFER_SIZE     2048    /* buffer for the variables */
  26 #define NUM_ENVP        32      /* number of env pointers */
  27
  28 #if defined(CONFIG_HOTPLUG)
  29 u64 uevent_seqnum;
  30 char uevent_helper[UEVENT_HELPER_PATH_LEN] = "/sbin/hotplug";
  31 static DEFINE_SPINLOCK(sequence_lock);
  32 #if defined(CONFIG_NET)
  33 static struct sock *uevent_sock;
  34 #endif
  35
  36 static char *action_to_string(enum kobject_action action)
  37 {
  38         switch (action) {
  39         case KOBJ_ADD:
  40                 return "add";
  41         case KOBJ_REMOVE:
  42                 return "remove";
  43         case KOBJ_CHANGE:
  44                 return "change";
  45         case KOBJ_OFFLINE:
  46                 return "offline";
  47         case KOBJ_ONLINE:
  48                 return "online";
  49         case KOBJ_MOVE:
  50                 return "move";
  51         default:
  52                 return NULL;
  53         }
  54 }
  55
  56 /**
  57  * kobject_uevent_env - send an uevent with environmental data
  58  *
  59  * @action: action that is happening (usually KOBJ_MOVE)
  60  * @kobj: struct kobject that the action is happening to
  61  * @envp_ext: pointer to environmental data
  62  *
  63  * Returns 0 if kobject_uevent() is completed with success or the
  64  * corresponding error when it fails.
  65  */
  66 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
  67                         char *envp_ext[])
  68 {
  69         char **envp;
  70         char *buffer;
  71         char *scratch;
  72         const char *action_string;
  73         const char *devpath = NULL;
  74         const char *subsystem;
  75         struct kobject *top_kobj;
  76         struct kset *kset;
  77         struct kset_uevent_ops *uevent_ops;
  78         u64 seq;
  79         char *seq_buff;
  80         int i = 0;
  81         int retval = 0;
  82         int j;
  83
  84         pr_debug("%s\n", __FUNCTION__);
  85
  86         action_string = action_to_string(action);
  87         if (!action_string) {
  88                 pr_debug("kobject attempted to send uevent without action_string!\n");
  89                 return -EINVAL;
  90         }
  91
  92         /* search the kset we belong to */
  93         top_kobj = kobj;
  94         while (!top_kobj->kset && top_kobj->parent) {
  95                 top_kobj = top_kobj->parent;
  96         }
  97         if (!top_kobj->kset) {
  98                 pr_debug("kobject attempted to send uevent without kset!\n");
  99                 return -EINVAL;
 100         }
 101
 102         kset = top_kobj->kset;
 103         uevent_ops = kset->uevent_ops;
 104
 105         /*  skip the event, if the filter returns zero. */
 106         if (uevent_ops && uevent_ops->filter)
 107                 if (!uevent_ops->filter(kset, kobj)) {
 108                         pr_debug("kobject filter function caused the event to drop!\n");
 109                         return 0;
 110                 }
 111
 112         /* originating subsystem */
 113         if (uevent_ops && uevent_ops->name)
 114                 subsystem = uevent_ops->name(kset, kobj);
 115         else
 116                 subsystem = kobject_name(&kset->kobj);
 117         if (!subsystem) {
 118                 pr_debug("unset subsytem caused the event to drop!\n");
 119                 return 0;
 120         }
 121
 122         /* environment index */
 123         envp = kzalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
 124         if (!envp)
 125                 return -ENOMEM;
 126
 127         /* environment values */
 128         buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
 129         if (!buffer) {
 130                 retval = -ENOMEM;
 131                 goto exit;
 132         }
 133
 134         /* complete object path */
 135         devpath = kobject_get_path(kobj, GFP_KERNEL);
 136         if (!devpath) {
 137                 retval = -ENOENT;
 138                 goto exit;
 139         }
 140
 141         /* event environemnt for helper process only */
 142         envp[i++] = "HOME=/";
 143         envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 144
 145         /* default keys */
 146         scratch = buffer;
 147         envp [i++] = scratch;
 148         scratch += sprintf(scratch, "ACTION=%s", action_string) + 1;
 149         envp [i++] = scratch;
 150         scratch += sprintf (scratch, "DEVPATH=%s", devpath) + 1;
 151         envp [i++] = scratch;
 152         scratch += sprintf(scratch, "SUBSYSTEM=%s", subsystem) + 1;
 153         for (j = 0; envp_ext && envp_ext[j]; j++)
 154                 envp[i++] = envp_ext[j];
 155         /* just reserve the space, overwrite it after kset call has returned */
 156         envp[i++] = seq_buff = scratch;
 157         scratch += strlen("SEQNUM=18446744073709551616") + 1;
 158
 159         /* let the kset specific function add its stuff */
 160         if (uevent_ops && uevent_ops->uevent) {
 161                 retval = uevent_ops->uevent(kset, kobj,
 162                                   &envp[i], NUM_ENVP - i, scratch,
 163                                   BUFFER_SIZE - (scratch - buffer));
 164                 if (retval) {
 165                         pr_debug ("%s - uevent() returned %d\n",
 166                                   __FUNCTION__, retval);
 167                         goto exit;
 168                 }
 169         }
 170
 171         /* we will send an event, request a new sequence number */
 172         spin_lock(&sequence_lock);
 173         seq = ++uevent_seqnum;
 174         spin_unlock(&sequence_lock);
 175         sprintf(seq_buff, "SEQNUM=%llu", (unsigned long long)seq);
 176
 177 #if defined(CONFIG_NET)
 178         /* send netlink message */
 179         if (uevent_sock) {
 180                 struct sk_buff *skb;
 181                 size_t len;
 182
 183                 /* allocate message with the maximum possible size */
 184                 len = strlen(action_string) + strlen(devpath) + 2;
 185                 skb = alloc_skb(len + BUFFER_SIZE, GFP_KERNEL);
 186                 if (skb) {
 187                         /* add header */
 188                         scratch = skb_put(skb, len);
 189                         sprintf(scratch, "%s@%s", action_string, devpath);
 190
 191                         /* copy keys to our continuous event payload buffer */
 192                         for (i = 2; envp[i]; i++) {
 193                                 len = strlen(envp[i]) + 1;
 194                                 scratch = skb_put(skb, len);
 195                                 strcpy(scratch, envp[i]);
 196                         }
 197
 198                         NETLINK_CB(skb).dst_group = 1;
 199                         netlink_broadcast(uevent_sock, skb, 0, 1, GFP_KERNEL);
 200                 }
 201         }
 202 #endif
 203
 204         /* call uevent_helper, usually only enabled during early boot */
 205         if (uevent_helper[0]) {
 206                 char *argv [3];
 207
 208                 argv [0] = uevent_helper;
 209                 argv [1] = (char *)subsystem;
 210                 argv [2] = NULL;
 211                 call_usermodehelper (argv[0], argv, envp, 0);
 212         }
 213
 214 exit:
 215         kfree(devpath);
 216         kfree(buffer);
 217         kfree(envp);
 218         return retval;
 219 }
 220
 221 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 222
 223 /**
 224  * kobject_uevent - notify userspace by ending an uevent
 225  *
 226  * @action: action that is happening (usually KOBJ_ADD and KOBJ_REMOVE)
 227  * @kobj: struct kobject that the action is happening to
 228  *
 229  * Returns 0 if kobject_uevent() is completed with success or the
 230  * corresponding error when it fails.
 231  */
 232 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 233 {
 234         return kobject_uevent_env(kobj, action, NULL);
 235 }
 236
 237 EXPORT_SYMBOL_GPL(kobject_uevent);
 238
 239 /**
 240  * add_uevent_var - helper for creating event variables
 241  * @envp: Pointer to table of environment variables, as passed into
 242  * uevent() method.
 243  * @num_envp: Number of environment variable slots available, as
 244  * passed into uevent() method.
 245  * @cur_index: Pointer to current index into @envp.  It should be
 246  * initialized to 0 before the first call to add_uevent_var(),
 247  * and will be incremented on success.
 248  * @buffer: Pointer to buffer for environment variables, as passed
 249  * into uevent() method.
 250  * @buffer_size: Length of @buffer, as passed into uevent() method.
 251  * @cur_len: Pointer to current length of space used in @buffer.
 252  * Should be initialized to 0 before the first call to
 253  * add_uevent_var(), and will be incremented on success.
 254  * @format: Format for creating environment variable (of the form
 255  * "XXX=%x") for snprintf().
 256  *
 257  * Returns 0 if environment variable was added successfully or -ENOMEM
 258  * if no space was available.
 259  */
 260 int add_uevent_var(char **envp, int num_envp, int *cur_index,
 261                    char *buffer, int buffer_size, int *cur_len,
 262                    const char *format, ...)
 263 {
 264         va_list args;
 265
 266         /*
 267          * We check against num_envp - 1 to make sure there is at
 268          * least one slot left after we return, since kobject_uevent()
 269          * needs to set the last slot to NULL.
 270          */
 271         if (*cur_index >= num_envp - 1)
 272                 return -ENOMEM;
 273
 274         envp[*cur_index] = buffer + *cur_len;
 275
 276         va_start(args, format);
 277         *cur_len += vsnprintf(envp[*cur_index],
 278                               max(buffer_size - *cur_len, 0),
 279                               format, args) + 1;
 280         va_end(args);
 281
 282         if (*cur_len > buffer_size)
 283                 return -ENOMEM;
 284
 285         (*cur_index)++;
 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(NETLINK_KOBJECT_UEVENT, 1, NULL,
 294                                             NULL, THIS_MODULE);
 295
 296         if (!uevent_sock) {
 297                 printk(KERN_ERR
 298                        "kobject_uevent: unable to create netlink socket!\n");
 299                 return -ENODEV;
 300         }
 301
 302         return 0;
 303 }
 304
 305 postcore_initcall(kobject_uevent_init);
 306 #endif
 307
 308 #endif /* CONFIG_HOTPLUG */