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_MOUNT:
  46                 return "mount";
  47         case KOBJ_UMOUNT:
  48                 return "umount";
  49         case KOBJ_OFFLINE:
  50                 return "offline";
  51         case KOBJ_ONLINE:
  52                 return "online";
  53         case KOBJ_MOVE:
  54                 return "move";
  55         default:
  56                 return NULL;
  57         }
  58 }
  59
  60 /**
  61  * kobject_uevent_env - send an uevent with environmental data
  62  *
  63  * @action: action that is happening (usually KOBJ_MOVE)
  64  * @kobj: struct kobject that the action is happening to
  65  * @envp_ext: pointer to environmental data
  66  *
  67  * Returns 0 if kobject_uevent() is completed with success or the
  68  * corresponding error when it fails.
  69  */
  70 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
  71                         char *envp_ext[])
  72 {
  73         char **envp;
  74         char *buffer;
  75         char *scratch;
  76         const char *action_string;
  77         const char *devpath = NULL;
  78         const char *subsystem;
  79         struct kobject *top_kobj;
  80         struct kset *kset;
  81         struct kset_uevent_ops *uevent_ops;
  82         u64 seq;
  83         char *seq_buff;
  84         int i = 0;
  85         int retval = 0;
  86         int j;
  87
  88         pr_debug("%s\n", __FUNCTION__);
  89
  90         action_string = action_to_string(action);
  91         if (!action_string) {
  92                 pr_debug("kobject attempted to send uevent without action_string!\n");
  93                 return -EINVAL;
  94         }
  95
  96         /* search the kset we belong to */
  97         top_kobj = kobj;
  98         if (!top_kobj->kset && top_kobj->parent) {
  99                 do {
 100                         top_kobj = top_kobj->parent;
 101                 } while (!top_kobj->kset && top_kobj->parent);
 102         }
 103         if (!top_kobj->kset) {
 104                 pr_debug("kobject attempted to send uevent without kset!\n");
 105                 return -EINVAL;
 106         }
 107
 108         kset = top_kobj->kset;
 109         uevent_ops = kset->uevent_ops;
 110
 111         /*  skip the event, if the filter returns zero. */
 112         if (uevent_ops && uevent_ops->filter)
 113                 if (!uevent_ops->filter(kset, kobj)) {
 114                         pr_debug("kobject filter function caused the event to drop!\n");
 115                         return 0;
 116                 }
 117
 118         /* environment index */
 119         envp = kzalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
 120         if (!envp)
 121                 return -ENOMEM;
 122
 123         /* environment values */
 124         buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
 125         if (!buffer) {
 126                 retval = -ENOMEM;
 127                 goto exit;
 128         }
 129
 130         /* complete object path */
 131         devpath = kobject_get_path(kobj, GFP_KERNEL);
 132         if (!devpath) {
 133                 retval = -ENOENT;
 134                 goto exit;
 135         }
 136
 137         /* originating subsystem */
 138         if (uevent_ops && uevent_ops->name)
 139                 subsystem = uevent_ops->name(kset, kobj);
 140         else
 141                 subsystem = kobject_name(&kset->kobj);
 142
 143         /* event environemnt for helper process only */
 144         envp[i++] = "HOME=/";
 145         envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 146
 147         /* default keys */
 148         scratch = buffer;
 149         envp [i++] = scratch;
 150         scratch += sprintf(scratch, "ACTION=%s", action_string) + 1;
 151         envp [i++] = scratch;
 152         scratch += sprintf (scratch, "DEVPATH=%s", devpath) + 1;
 153         envp [i++] = scratch;
 154         scratch += sprintf(scratch, "SUBSYSTEM=%s", subsystem) + 1;
 155         for (j = 0; envp_ext && envp_ext[j]; j++)
 156                 envp[i++] = envp_ext[j];
 157         /* just reserve the space, overwrite it after kset call has returned */
 158         envp[i++] = seq_buff = scratch;
 159         scratch += strlen("SEQNUM=18446744073709551616") + 1;
 160
 161         /* let the kset specific function add its stuff */
 162         if (uevent_ops && uevent_ops->uevent) {
 163                 retval = uevent_ops->uevent(kset, kobj,
 164                                   &envp[i], NUM_ENVP - i, scratch,
 165                                   BUFFER_SIZE - (scratch - buffer));
 166                 if (retval) {
 167                         pr_debug ("%s - uevent() returned %d\n",
 168                                   __FUNCTION__, retval);
 169                         goto exit;
 170                 }
 171         }
 172
 173         /* we will send an event, request a new sequence number */
 174         spin_lock(&sequence_lock);
 175         seq = ++uevent_seqnum;
 176         spin_unlock(&sequence_lock);
 177         sprintf(seq_buff, "SEQNUM=%llu", (unsigned long long)seq);
 178
 179 #if defined(CONFIG_NET)
 180         /* send netlink message */
 181         if (uevent_sock) {
 182                 struct sk_buff *skb;
 183                 size_t len;
 184
 185                 /* allocate message with the maximum possible size */
 186                 len = strlen(action_string) + strlen(devpath) + 2;
 187                 skb = alloc_skb(len + BUFFER_SIZE, GFP_KERNEL);
 188                 if (skb) {
 189                         /* add header */
 190                         scratch = skb_put(skb, len);
 191                         sprintf(scratch, "%s@%s", action_string, devpath);
 192
 193                         /* copy keys to our continuous event payload buffer */
 194                         for (i = 2; envp[i]; i++) {
 195                                 len = strlen(envp[i]) + 1;
 196                                 scratch = skb_put(skb, len);
 197                                 strcpy(scratch, envp[i]);
 198                         }
 199
 200                         NETLINK_CB(skb).dst_group = 1;
 201                         netlink_broadcast(uevent_sock, skb, 0, 1, GFP_KERNEL);
 202                 }
 203         }
 204 #endif
 205
 206         /* call uevent_helper, usually only enabled during early boot */
 207         if (uevent_helper[0]) {
 208                 char *argv [3];
 209
 210                 argv [0] = uevent_helper;
 211                 argv [1] = (char *)subsystem;
 212                 argv [2] = NULL;
 213                 call_usermodehelper (argv[0], argv, envp, 0);
 214         }
 215
 216 exit:
 217         kfree(devpath);
 218         kfree(buffer);
 219         kfree(envp);
 220         return retval;
 221 }
 222
 223 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 224
 225 /**
 226  * kobject_uevent - notify userspace by ending an uevent
 227  *
 228  * @action: action that is happening (usually KOBJ_ADD and KOBJ_REMOVE)
 229  * @kobj: struct kobject that the action is happening to
 230  *
 231  * Returns 0 if kobject_uevent() is completed with success or the
 232  * corresponding error when it fails.
 233  */
 234 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 235 {
 236         return kobject_uevent_env(kobj, action, NULL);
 237 }
 238
 239 EXPORT_SYMBOL_GPL(kobject_uevent);
 240
 241 /**
 242  * add_uevent_var - helper for creating event variables
 243  * @envp: Pointer to table of environment variables, as passed into
 244  * uevent() method.
 245  * @num_envp: Number of environment variable slots available, as
 246  * passed into uevent() method.
 247  * @cur_index: Pointer to current index into @envp.  It should be
 248  * initialized to 0 before the first call to add_uevent_var(),
 249  * and will be incremented on success.
 250  * @buffer: Pointer to buffer for environment variables, as passed
 251  * into uevent() method.
 252  * @buffer_size: Length of @buffer, as passed into uevent() method.
 253  * @cur_len: Pointer to current length of space used in @buffer.
 254  * Should be initialized to 0 before the first call to
 255  * add_uevent_var(), and will be incremented on success.
 256  * @format: Format for creating environment variable (of the form
 257  * "XXX=%x") for snprintf().
 258  *
 259  * Returns 0 if environment variable was added successfully or -ENOMEM
 260  * if no space was available.
 261  */
 262 int add_uevent_var(char **envp, int num_envp, int *cur_index,
 263                    char *buffer, int buffer_size, int *cur_len,
 264                    const char *format, ...)
 265 {
 266         va_list args;
 267
 268         /*
 269          * We check against num_envp - 1 to make sure there is at
 270          * least one slot left after we return, since kobject_uevent()
 271          * needs to set the last slot to NULL.
 272          */
 273         if (*cur_index >= num_envp - 1)
 274                 return -ENOMEM;
 275
 276         envp[*cur_index] = buffer + *cur_len;
 277
 278         va_start(args, format);
 279         *cur_len += vsnprintf(envp[*cur_index],
 280                               max(buffer_size - *cur_len, 0),
 281                               format, args) + 1;
 282         va_end(args);
 283
 284         if (*cur_len > buffer_size)
 285                 return -ENOMEM;
 286
 287         (*cur_index)++;
 288         return 0;
 289 }
 290 EXPORT_SYMBOL_GPL(add_uevent_var);
 291
 292 #if defined(CONFIG_NET)
 293 static int __init kobject_uevent_init(void)
 294 {
 295         uevent_sock = netlink_kernel_create(NETLINK_KOBJECT_UEVENT, 1, NULL,
 296                                             THIS_MODULE);
 297
 298         if (!uevent_sock) {
 299                 printk(KERN_ERR
 300                        "kobject_uevent: unable to create netlink socket!\n");
 301                 return -ENODEV;
 302         }
 303
 304         return 0;
 305 }
 306
 307 postcore_initcall(kobject_uevent_init);
 308 #endif
 309
 310 #endif /* CONFIG_HOTPLUG */