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_uevent.h>
  23 #include <linux/kobject.h>
  24 #include <net/sock.h>
  25
  26 #define BUFFER_SIZE     1024    /* buffer for the hotplug env */
  27 #define NUM_ENVP        32      /* number of env pointers */
  28
  29 #if defined(CONFIG_KOBJECT_UEVENT) || defined(CONFIG_HOTPLUG)
  30 static char *action_to_string(enum kobject_action action)
  31 {
  32         switch (action) {
  33         case KOBJ_ADD:
  34                 return "add";
  35         case KOBJ_REMOVE:
  36                 return "remove";
  37         case KOBJ_CHANGE:
  38                 return "change";
  39         case KOBJ_MOUNT:
  40                 return "mount";
  41         case KOBJ_UMOUNT:
  42                 return "umount";
  43         case KOBJ_OFFLINE:
  44                 return "offline";
  45         case KOBJ_ONLINE:
  46                 return "online";
  47         default:
  48                 return NULL;
  49         }
  50 }
  51 #endif
  52
  53 #ifdef CONFIG_KOBJECT_UEVENT
  54 static struct sock *uevent_sock;
  55
  56 /**
  57  * send_uevent - notify userspace by sending event through netlink socket
  58  *
  59  * @signal: signal name
  60  * @obj: object path (kobject)
  61  * @envp: possible hotplug environment to pass with the message
  62  * @gfp_mask:
  63  */
  64 static int send_uevent(const char *signal, const char *obj,
  65                        char **envp, gfp_t gfp_mask)
  66 {
  67         struct sk_buff *skb;
  68         char *pos;
  69         int len;
  70
  71         if (!uevent_sock)
  72                 return -EIO;
  73
  74         len = strlen(signal) + 1;
  75         len += strlen(obj) + 1;
  76
  77         /* allocate buffer with the maximum possible message size */
  78         skb = alloc_skb(len + BUFFER_SIZE, gfp_mask);
  79         if (!skb)
  80                 return -ENOMEM;
  81
  82         pos = skb_put(skb, len);
  83         sprintf(pos, "%s@%s", signal, obj);
  84
  85         /* copy the environment key by key to our continuous buffer */
  86         if (envp) {
  87                 int i;
  88
  89                 for (i = 2; envp[i]; i++) {
  90                         len = strlen(envp[i]) + 1;
  91                         pos = skb_put(skb, len);
  92                         strcpy(pos, envp[i]);
  93                 }
  94         }
  95
  96         NETLINK_CB(skb).dst_group = 1;
  97         return netlink_broadcast(uevent_sock, skb, 0, 1, gfp_mask);
  98 }
  99
 100 static int do_kobject_uevent(struct kobject *kobj, enum kobject_action action,
 101                              struct attribute *attr, gfp_t gfp_mask)
 102 {
 103         char *path;
 104         char *attrpath;
 105         char *signal;
 106         int len;
 107         int rc = -ENOMEM;
 108
 109         path = kobject_get_path(kobj, gfp_mask);
 110         if (!path)
 111                 return -ENOMEM;
 112
 113         signal = action_to_string(action);
 114         if (!signal)
 115                 return -EINVAL;
 116
 117         if (attr) {
 118                 len = strlen(path);
 119                 len += strlen(attr->name) + 2;
 120                 attrpath = kmalloc(len, gfp_mask);
 121                 if (!attrpath)
 122                         goto exit;
 123                 sprintf(attrpath, "%s/%s", path, attr->name);
 124                 rc = send_uevent(signal, attrpath, NULL, gfp_mask);
 125                 kfree(attrpath);
 126         } else
 127                 rc = send_uevent(signal, path, NULL, gfp_mask);
 128
 129 exit:
 130         kfree(path);
 131         return rc;
 132 }
 133
 134 /**
 135  * kobject_uevent - notify userspace by sending event through netlink socket
 136  *
 137  * @signal: signal name
 138  * @kobj: struct kobject that the event is happening to
 139  * @attr: optional struct attribute the event belongs to
 140  */
 141 int kobject_uevent(struct kobject *kobj, enum kobject_action action,
 142                    struct attribute *attr)
 143 {
 144         return do_kobject_uevent(kobj, action, attr, GFP_KERNEL);
 145 }
 146 EXPORT_SYMBOL_GPL(kobject_uevent);
 147
 148 int kobject_uevent_atomic(struct kobject *kobj, enum kobject_action action,
 149                           struct attribute *attr)
 150 {
 151         return do_kobject_uevent(kobj, action, attr, GFP_ATOMIC);
 152 }
 153 EXPORT_SYMBOL_GPL(kobject_uevent_atomic);
 154
 155 static int __init kobject_uevent_init(void)
 156 {
 157         uevent_sock = netlink_kernel_create(NETLINK_KOBJECT_UEVENT, 1, NULL,
 158                                             THIS_MODULE);
 159
 160         if (!uevent_sock) {
 161                 printk(KERN_ERR
 162                        "kobject_uevent: unable to create netlink socket!\n");
 163                 return -ENODEV;
 164         }
 165
 166         return 0;
 167 }
 168
 169 postcore_initcall(kobject_uevent_init);
 170
 171 #else
 172 static inline int send_uevent(const char *signal, const char *obj,
 173                               char **envp, int gfp_mask)
 174 {
 175         return 0;
 176 }
 177
 178 #endif /* CONFIG_KOBJECT_UEVENT */
 179
 180
 181 #ifdef CONFIG_HOTPLUG
 182 char hotplug_path[HOTPLUG_PATH_LEN] = "/sbin/hotplug";
 183 u64 hotplug_seqnum;
 184 static DEFINE_SPINLOCK(sequence_lock);
 185
 186 /**
 187  * kobject_hotplug - notify userspace by executing /sbin/hotplug
 188  *
 189  * @action: action that is happening (usually "ADD" or "REMOVE")
 190  * @kobj: struct kobject that the action is happening to
 191  */
 192 void kobject_hotplug(struct kobject *kobj, enum kobject_action action)
 193 {
 194         char *argv [3];
 195         char **envp = NULL;
 196         char *buffer = NULL;
 197         char *seq_buff;
 198         char *scratch;
 199         int i = 0;
 200         int retval;
 201         char *kobj_path = NULL;
 202         const char *name = NULL;
 203         char *action_string;
 204         u64 seq;
 205         struct kobject *top_kobj = kobj;
 206         struct kset *kset;
 207         static struct kset_hotplug_ops null_hotplug_ops;
 208         struct kset_hotplug_ops *hotplug_ops = &null_hotplug_ops;
 209
 210         /* If this kobj does not belong to a kset,
 211            try to find a parent that does. */
 212         if (!top_kobj->kset && top_kobj->parent) {
 213                 do {
 214                         top_kobj = top_kobj->parent;
 215                 } while (!top_kobj->kset && top_kobj->parent);
 216         }
 217
 218         if (top_kobj->kset)
 219                 kset = top_kobj->kset;
 220         else
 221                 return;
 222
 223         if (kset->hotplug_ops)
 224                 hotplug_ops = kset->hotplug_ops;
 225
 226         /* If the kset has a filter operation, call it.
 227            Skip the event, if the filter returns zero. */
 228         if (hotplug_ops->filter) {
 229                 if (!hotplug_ops->filter(kset, kobj))
 230                         return;
 231         }
 232
 233         pr_debug ("%s\n", __FUNCTION__);
 234
 235         action_string = action_to_string(action);
 236         if (!action_string)
 237                 return;
 238
 239         envp = kmalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
 240         if (!envp)
 241                 return;
 242         memset (envp, 0x00, NUM_ENVP * sizeof (char *));
 243
 244         buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
 245         if (!buffer)
 246                 goto exit;
 247
 248         if (hotplug_ops->name)
 249                 name = hotplug_ops->name(kset, kobj);
 250         if (name == NULL)
 251                 name = kobject_name(&kset->kobj);
 252
 253         argv [0] = hotplug_path;
 254         argv [1] = (char *)name; /* won't be changed but 'const' has to go */
 255         argv [2] = NULL;
 256
 257         /* minimal command environment */
 258         envp [i++] = "HOME=/";
 259         envp [i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 260
 261         scratch = buffer;
 262
 263         envp [i++] = scratch;
 264         scratch += sprintf(scratch, "ACTION=%s", action_string) + 1;
 265
 266         kobj_path = kobject_get_path(kobj, GFP_KERNEL);
 267         if (!kobj_path)
 268                 goto exit;
 269
 270         envp [i++] = scratch;
 271         scratch += sprintf (scratch, "DEVPATH=%s", kobj_path) + 1;
 272
 273         envp [i++] = scratch;
 274         scratch += sprintf(scratch, "SUBSYSTEM=%s", name) + 1;
 275
 276         /* reserve space for the sequence,
 277          * put the real one in after the hotplug call */
 278         envp[i++] = seq_buff = scratch;
 279         scratch += strlen("SEQNUM=18446744073709551616") + 1;
 280
 281         if (hotplug_ops->hotplug) {
 282                 /* have the kset specific function add its stuff */
 283                 retval = hotplug_ops->hotplug (kset, kobj,
 284                                   &envp[i], NUM_ENVP - i, scratch,
 285                                   BUFFER_SIZE - (scratch - buffer));
 286                 if (retval) {
 287                         pr_debug ("%s - hotplug() returned %d\n",
 288                                   __FUNCTION__, retval);
 289                         goto exit;
 290                 }
 291         }
 292
 293         spin_lock(&sequence_lock);
 294         seq = ++hotplug_seqnum;
 295         spin_unlock(&sequence_lock);
 296         sprintf(seq_buff, "SEQNUM=%llu", (unsigned long long)seq);
 297
 298         pr_debug ("%s: %s %s seq=%llu %s %s %s %s %s\n",
 299                   __FUNCTION__, argv[0], argv[1], (unsigned long long)seq,
 300                   envp[0], envp[1], envp[2], envp[3], envp[4]);
 301
 302         send_uevent(action_string, kobj_path, envp, GFP_KERNEL);
 303
 304         if (!hotplug_path[0])
 305                 goto exit;
 306
 307         retval = call_usermodehelper (argv[0], argv, envp, 0);
 308         if (retval)
 309                 pr_debug ("%s - call_usermodehelper returned %d\n",
 310                           __FUNCTION__, retval);
 311
 312 exit:
 313         kfree(kobj_path);
 314         kfree(buffer);
 315         kfree(envp);
 316         return;
 317 }
 318 EXPORT_SYMBOL(kobject_hotplug);
 319
 320 /**
 321  * add_hotplug_env_var - helper for creating hotplug environment variables
 322  * @envp: Pointer to table of environment variables, as passed into
 323  * hotplug() method.
 324  * @num_envp: Number of environment variable slots available, as
 325  * passed into hotplug() method.
 326  * @cur_index: Pointer to current index into @envp.  It should be
 327  * initialized to 0 before the first call to add_hotplug_env_var(),
 328  * and will be incremented on success.
 329  * @buffer: Pointer to buffer for environment variables, as passed
 330  * into hotplug() method.
 331  * @buffer_size: Length of @buffer, as passed into hotplug() method.
 332  * @cur_len: Pointer to current length of space used in @buffer.
 333  * Should be initialized to 0 before the first call to
 334  * add_hotplug_env_var(), and will be incremented on success.
 335  * @format: Format for creating environment variable (of the form
 336  * "XXX=%x") for snprintf().
 337  *
 338  * Returns 0 if environment variable was added successfully or -ENOMEM
 339  * if no space was available.
 340  */
 341 int add_hotplug_env_var(char **envp, int num_envp, int *cur_index,
 342                         char *buffer, int buffer_size, int *cur_len,
 343                         const char *format, ...)
 344 {
 345         va_list args;
 346
 347         /*
 348          * We check against num_envp - 1 to make sure there is at
 349          * least one slot left after we return, since the hotplug
 350          * method needs to set the last slot to NULL.
 351          */
 352         if (*cur_index >= num_envp - 1)
 353                 return -ENOMEM;
 354
 355         envp[*cur_index] = buffer + *cur_len;
 356
 357         va_start(args, format);
 358         *cur_len += vsnprintf(envp[*cur_index],
 359                               max(buffer_size - *cur_len, 0),
 360                               format, args) + 1;
 361         va_end(args);
 362
 363         if (*cur_len > buffer_size)
 364                 return -ENOMEM;
 365
 366         (*cur_index)++;
 367         return 0;
 368 }
 369 EXPORT_SYMBOL(add_hotplug_env_var);
 370
 371 #endif /* CONFIG_HOTPLUG */