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 /* the strings here must match the enum in include/linux/kobject.h */
  29 const char *kobject_actions[] = {
  30         "add",
  31         "remove",
  32         "change",
  33         "move",
  34         "online",
  35         "offline",
  36 };
  37
  38 #if defined(CONFIG_HOTPLUG)
  39 u64 uevent_seqnum;
  40 char uevent_helper[UEVENT_HELPER_PATH_LEN] = "/sbin/hotplug";
  41 static DEFINE_SPINLOCK(sequence_lock);
  42 #if defined(CONFIG_NET)
  43 static struct sock *uevent_sock;
  44 #endif
  45
  46 /**
  47  * kobject_uevent_env - send an uevent with environmental data
  48  *
  49  * @action: action that is happening (usually KOBJ_MOVE)
  50  * @kobj: struct kobject that the action is happening to
  51  * @envp_ext: pointer to environmental data
  52  *
  53  * Returns 0 if kobject_uevent() is completed with success or the
  54  * corresponding error when it fails.
  55  */
  56 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
  57                         char *envp_ext[])
  58 {
  59         char **envp;
  60         char *buffer;
  61         char *scratch;
  62         const char *action_string;
  63         const char *devpath = NULL;
  64         const char *subsystem;
  65         struct kobject *top_kobj;
  66         struct kset *kset;
  67         struct kset_uevent_ops *uevent_ops;
  68         u64 seq;
  69         char *seq_buff;
  70         int i = 0;
  71         int retval = 0;
  72         int j;
  73
  74         pr_debug("%s\n", __FUNCTION__);
  75
  76         action_string = kobject_actions[action];
  77         if (!action_string) {
  78                 pr_debug("kobject attempted to send uevent without action_string!\n");
  79                 return -EINVAL;
  80         }
  81
  82         /* search the kset we belong to */
  83         top_kobj = kobj;
  84         while (!top_kobj->kset && top_kobj->parent) {
  85                 top_kobj = top_kobj->parent;
  86         }
  87         if (!top_kobj->kset) {
  88                 pr_debug("kobject attempted to send uevent without kset!\n");
  89                 return -EINVAL;
  90         }
  91
  92         kset = top_kobj->kset;
  93         uevent_ops = kset->uevent_ops;
  94
  95         /*  skip the event, if the filter returns zero. */
  96         if (uevent_ops && uevent_ops->filter)
  97                 if (!uevent_ops->filter(kset, kobj)) {
  98                         pr_debug("kobject filter function caused the event to drop!\n");
  99                         return 0;
 100                 }
 101
 102         /* originating subsystem */
 103         if (uevent_ops && uevent_ops->name)
 104                 subsystem = uevent_ops->name(kset, kobj);
 105         else
 106                 subsystem = kobject_name(&kset->kobj);
 107         if (!subsystem) {
 108                 pr_debug("unset subsytem caused the event to drop!\n");
 109                 return 0;
 110         }
 111
 112         /* environment index */
 113         envp = kzalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
 114         if (!envp)
 115                 return -ENOMEM;
 116
 117         /* environment values */
 118         buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
 119         if (!buffer) {
 120                 retval = -ENOMEM;
 121                 goto exit;
 122         }
 123
 124         /* complete object path */
 125         devpath = kobject_get_path(kobj, GFP_KERNEL);
 126         if (!devpath) {
 127                 retval = -ENOENT;
 128                 goto exit;
 129         }
 130
 131         /* event environemnt for helper process only */
 132         envp[i++] = "HOME=/";
 133         envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 134
 135         /* default keys */
 136         scratch = buffer;
 137         envp [i++] = scratch;
 138         scratch += sprintf(scratch, "ACTION=%s", action_string) + 1;
 139         envp [i++] = scratch;
 140         scratch += sprintf (scratch, "DEVPATH=%s", devpath) + 1;
 141         envp [i++] = scratch;
 142         scratch += sprintf(scratch, "SUBSYSTEM=%s", subsystem) + 1;
 143         for (j = 0; envp_ext && envp_ext[j]; j++)
 144                 envp[i++] = envp_ext[j];
 145         /* just reserve the space, overwrite it after kset call has returned */
 146         envp[i++] = seq_buff = scratch;
 147         scratch += strlen("SEQNUM=18446744073709551616") + 1;
 148
 149         /* let the kset specific function add its stuff */
 150         if (uevent_ops && uevent_ops->uevent) {
 151                 retval = uevent_ops->uevent(kset, kobj,
 152                                   &envp[i], NUM_ENVP - i, scratch,
 153                                   BUFFER_SIZE - (scratch - buffer));
 154                 if (retval) {
 155                         pr_debug ("%s - uevent() returned %d\n",
 156                                   __FUNCTION__, retval);
 157                         goto exit;
 158                 }
 159         }
 160
 161         /* we will send an event, request a new sequence number */
 162         spin_lock(&sequence_lock);
 163         seq = ++uevent_seqnum;
 164         spin_unlock(&sequence_lock);
 165         sprintf(seq_buff, "SEQNUM=%llu", (unsigned long long)seq);
 166
 167 #if defined(CONFIG_NET)
 168         /* send netlink message */
 169         if (uevent_sock) {
 170                 struct sk_buff *skb;
 171                 size_t len;
 172
 173                 /* allocate message with the maximum possible size */
 174                 len = strlen(action_string) + strlen(devpath) + 2;
 175                 skb = alloc_skb(len + BUFFER_SIZE, GFP_KERNEL);
 176                 if (skb) {
 177                         /* add header */
 178                         scratch = skb_put(skb, len);
 179                         sprintf(scratch, "%s@%s", action_string, devpath);
 180
 181                         /* copy keys to our continuous event payload buffer */
 182                         for (i = 2; envp[i]; i++) {
 183                                 len = strlen(envp[i]) + 1;
 184                                 scratch = skb_put(skb, len);
 185                                 strcpy(scratch, envp[i]);
 186                         }
 187
 188                         NETLINK_CB(skb).dst_group = 1;
 189                         netlink_broadcast(uevent_sock, skb, 0, 1, GFP_KERNEL);
 190                 }
 191         }
 192 #endif
 193
 194         /* call uevent_helper, usually only enabled during early boot */
 195         if (uevent_helper[0]) {
 196                 char *argv [3];
 197
 198                 argv [0] = uevent_helper;
 199                 argv [1] = (char *)subsystem;
 200                 argv [2] = NULL;
 201                 call_usermodehelper (argv[0], argv, envp, UMH_WAIT_EXEC);
 202         }
 203
 204 exit:
 205         kfree(devpath);
 206         kfree(buffer);
 207         kfree(envp);
 208         return retval;
 209 }
 210
 211 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 212
 213 /**
 214  * kobject_uevent - notify userspace by ending an uevent
 215  *
 216  * @action: action that is happening (usually KOBJ_ADD and KOBJ_REMOVE)
 217  * @kobj: struct kobject that the action is happening to
 218  *
 219  * Returns 0 if kobject_uevent() is completed with success or the
 220  * corresponding error when it fails.
 221  */
 222 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 223 {
 224         return kobject_uevent_env(kobj, action, NULL);
 225 }
 226
 227 EXPORT_SYMBOL_GPL(kobject_uevent);
 228
 229 /**
 230  * add_uevent_var - helper for creating event variables
 231  * @envp: Pointer to table of environment variables, as passed into
 232  * uevent() method.
 233  * @num_envp: Number of environment variable slots available, as
 234  * passed into uevent() method.
 235  * @cur_index: Pointer to current index into @envp.  It should be
 236  * initialized to 0 before the first call to add_uevent_var(),
 237  * and will be incremented on success.
 238  * @buffer: Pointer to buffer for environment variables, as passed
 239  * into uevent() method.
 240  * @buffer_size: Length of @buffer, as passed into uevent() method.
 241  * @cur_len: Pointer to current length of space used in @buffer.
 242  * Should be initialized to 0 before the first call to
 243  * add_uevent_var(), and will be incremented on success.
 244  * @format: Format for creating environment variable (of the form
 245  * "XXX=%x") for snprintf().
 246  *
 247  * Returns 0 if environment variable was added successfully or -ENOMEM
 248  * if no space was available.
 249  */
 250 int add_uevent_var(char **envp, int num_envp, int *cur_index,
 251                    char *buffer, int buffer_size, int *cur_len,
 252                    const char *format, ...)
 253 {
 254         va_list args;
 255
 256         /*
 257          * We check against num_envp - 1 to make sure there is at
 258          * least one slot left after we return, since kobject_uevent()
 259          * needs to set the last slot to NULL.
 260          */
 261         if (*cur_index >= num_envp - 1)
 262                 return -ENOMEM;
 263
 264         envp[*cur_index] = buffer + *cur_len;
 265
 266         va_start(args, format);
 267         *cur_len += vsnprintf(envp[*cur_index],
 268                               max(buffer_size - *cur_len, 0),
 269                               format, args) + 1;
 270         va_end(args);
 271
 272         if (*cur_len > buffer_size)
 273                 return -ENOMEM;
 274
 275         (*cur_index)++;
 276         return 0;
 277 }
 278 EXPORT_SYMBOL_GPL(add_uevent_var);
 279
 280 #if defined(CONFIG_NET)
 281 static int __init kobject_uevent_init(void)
 282 {
 283         uevent_sock = netlink_kernel_create(NETLINK_KOBJECT_UEVENT, 1, NULL,
 284                                             NULL, THIS_MODULE);
 285
 286         if (!uevent_sock) {
 287                 printk(KERN_ERR
 288                        "kobject_uevent: unable to create netlink socket!\n");
 289                 return -ENODEV;
 290         }
 291
 292         return 0;
 293 }
 294
 295 postcore_initcall(kobject_uevent_init);
 296 #endif
 297
 298 #endif /* CONFIG_HOTPLUG */