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 void kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
  68                         char *envp_ext[])
  69 {
  70         char **envp;
  71         char *buffer;
  72         char *scratch;
  73         const char *action_string;
  74         const char *devpath = NULL;
  75         const char *subsystem;
  76         struct kobject *top_kobj;
  77         struct kset *kset;
  78         struct kset_uevent_ops *uevent_ops;
  79         u64 seq;
  80         char *seq_buff;
  81         int i = 0;
  82         int retval;
  83         int j;
  84
  85         pr_debug("%s\n", __FUNCTION__);
  86
  87         action_string = action_to_string(action);
  88         if (!action_string)
  89                 return;
  90
  91         /* search the kset we belong to */
  92         top_kobj = kobj;
  93         if (!top_kobj->kset && top_kobj->parent) {
  94                 do {
  95                         top_kobj = top_kobj->parent;
  96                 } while (!top_kobj->kset && top_kobj->parent);
  97         }
  98         if (!top_kobj->kset)
  99                 return;
 100
 101         kset = top_kobj->kset;
 102         uevent_ops = kset->uevent_ops;
 103
 104         /*  skip the event, if the filter returns zero. */
 105         if (uevent_ops && uevent_ops->filter)
 106                 if (!uevent_ops->filter(kset, kobj))
 107                         return;
 108
 109         /* environment index */
 110         envp = kzalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
 111         if (!envp)
 112                 return;
 113
 114         /* environment values */
 115         buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
 116         if (!buffer)
 117                 goto exit;
 118
 119         /* complete object path */
 120         devpath = kobject_get_path(kobj, GFP_KERNEL);
 121         if (!devpath)
 122                 goto exit;
 123
 124         /* originating subsystem */
 125         if (uevent_ops && uevent_ops->name)
 126                 subsystem = uevent_ops->name(kset, kobj);
 127         else
 128                 subsystem = kobject_name(&kset->kobj);
 129
 130         /* event environemnt for helper process only */
 131         envp[i++] = "HOME=/";
 132         envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 133
 134         /* default keys */
 135         scratch = buffer;
 136         envp [i++] = scratch;
 137         scratch += sprintf(scratch, "ACTION=%s", action_string) + 1;
 138         envp [i++] = scratch;
 139         scratch += sprintf (scratch, "DEVPATH=%s", devpath) + 1;
 140         envp [i++] = scratch;
 141         scratch += sprintf(scratch, "SUBSYSTEM=%s", subsystem) + 1;
 142         for (j = 0; envp_ext && envp_ext[j]; j++)
 143                 envp[i++] = envp_ext[j];
 144         /* just reserve the space, overwrite it after kset call has returned */
 145         envp[i++] = seq_buff = scratch;
 146         scratch += strlen("SEQNUM=18446744073709551616") + 1;
 147
 148         /* let the kset specific function add its stuff */
 149         if (uevent_ops && uevent_ops->uevent) {
 150                 retval = uevent_ops->uevent(kset, kobj,
 151                                   &envp[i], NUM_ENVP - i, scratch,
 152                                   BUFFER_SIZE - (scratch - buffer));
 153                 if (retval) {
 154                         pr_debug ("%s - uevent() returned %d\n",
 155                                   __FUNCTION__, retval);
 156                         goto exit;
 157                 }
 158         }
 159
 160         /* we will send an event, request a new sequence number */
 161         spin_lock(&sequence_lock);
 162         seq = ++uevent_seqnum;
 163         spin_unlock(&sequence_lock);
 164         sprintf(seq_buff, "SEQNUM=%llu", (unsigned long long)seq);
 165
 166 #if defined(CONFIG_NET)
 167         /* send netlink message */
 168         if (uevent_sock) {
 169                 struct sk_buff *skb;
 170                 size_t len;
 171
 172                 /* allocate message with the maximum possible size */
 173                 len = strlen(action_string) + strlen(devpath) + 2;
 174                 skb = alloc_skb(len + BUFFER_SIZE, GFP_KERNEL);
 175                 if (skb) {
 176                         /* add header */
 177                         scratch = skb_put(skb, len);
 178                         sprintf(scratch, "%s@%s", action_string, devpath);
 179
 180                         /* copy keys to our continuous event payload buffer */
 181                         for (i = 2; envp[i]; i++) {
 182                                 len = strlen(envp[i]) + 1;
 183                                 scratch = skb_put(skb, len);
 184                                 strcpy(scratch, envp[i]);
 185                         }
 186
 187                         NETLINK_CB(skb).dst_group = 1;
 188                         netlink_broadcast(uevent_sock, skb, 0, 1, GFP_KERNEL);
 189                 }
 190         }
 191 #endif
 192
 193         /* call uevent_helper, usually only enabled during early boot */
 194         if (uevent_helper[0]) {
 195                 char *argv [3];
 196
 197                 argv [0] = uevent_helper;
 198                 argv [1] = (char *)subsystem;
 199                 argv [2] = NULL;
 200                 call_usermodehelper (argv[0], argv, envp, 0);
 201         }
 202
 203 exit:
 204         kfree(devpath);
 205         kfree(buffer);
 206         kfree(envp);
 207         return;
 208 }
 209
 210 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 211
 212 /**
 213  * kobject_uevent - notify userspace by ending an uevent
 214  *
 215  * @action: action that is happening (usually KOBJ_ADD and KOBJ_REMOVE)
 216  * @kobj: struct kobject that the action is happening to
 217  */
 218 void kobject_uevent(struct kobject *kobj, enum kobject_action action)
 219 {
 220         kobject_uevent_env(kobj, action, NULL);
 221 }
 222
 223 EXPORT_SYMBOL_GPL(kobject_uevent);
 224
 225 /**
 226  * add_uevent_var - helper for creating event variables
 227  * @envp: Pointer to table of environment variables, as passed into
 228  * uevent() method.
 229  * @num_envp: Number of environment variable slots available, as
 230  * passed into uevent() method.
 231  * @cur_index: Pointer to current index into @envp.  It should be
 232  * initialized to 0 before the first call to add_uevent_var(),
 233  * and will be incremented on success.
 234  * @buffer: Pointer to buffer for environment variables, as passed
 235  * into uevent() method.
 236  * @buffer_size: Length of @buffer, as passed into uevent() method.
 237  * @cur_len: Pointer to current length of space used in @buffer.
 238  * Should be initialized to 0 before the first call to
 239  * add_uevent_var(), and will be incremented on success.
 240  * @format: Format for creating environment variable (of the form
 241  * "XXX=%x") for snprintf().
 242  *
 243  * Returns 0 if environment variable was added successfully or -ENOMEM
 244  * if no space was available.
 245  */
 246 int add_uevent_var(char **envp, int num_envp, int *cur_index,
 247                    char *buffer, int buffer_size, int *cur_len,
 248                    const char *format, ...)
 249 {
 250         va_list args;
 251
 252         /*
 253          * We check against num_envp - 1 to make sure there is at
 254          * least one slot left after we return, since kobject_uevent()
 255          * needs to set the last slot to NULL.
 256          */
 257         if (*cur_index >= num_envp - 1)
 258                 return -ENOMEM;
 259
 260         envp[*cur_index] = buffer + *cur_len;
 261
 262         va_start(args, format);
 263         *cur_len += vsnprintf(envp[*cur_index],
 264                               max(buffer_size - *cur_len, 0),
 265                               format, args) + 1;
 266         va_end(args);
 267
 268         if (*cur_len > buffer_size)
 269                 return -ENOMEM;
 270
 271         (*cur_index)++;
 272         return 0;
 273 }
 274 EXPORT_SYMBOL_GPL(add_uevent_var);
 275
 276 #if defined(CONFIG_NET)
 277 static int __init kobject_uevent_init(void)
 278 {
 279         uevent_sock = netlink_kernel_create(NETLINK_KOBJECT_UEVENT, 1, NULL,
 280                                             THIS_MODULE);
 281
 282         if (!uevent_sock) {
 283                 printk(KERN_ERR
 284                        "kobject_uevent: unable to create netlink socket!\n");
 285                 return -ENODEV;
 286         }
 287
 288         return 0;
 289 }
 290
 291 postcore_initcall(kobject_uevent_init);
 292 #endif
 293
 294 #endif /* CONFIG_HOTPLUG */