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 trough 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, int 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         return netlink_broadcast(uevent_sock, skb, 0, 1, gfp_mask);
  97 }
  98
  99 static int do_kobject_uevent(struct kobject *kobj, enum kobject_action action,
 100                              struct attribute *attr, int gfp_mask)
 101 {
 102         char *path;
 103         char *attrpath;
 104         char *signal;
 105         int len;
 106         int rc = -ENOMEM;
 107
 108         path = kobject_get_path(kobj, gfp_mask);
 109         if (!path)
 110                 return -ENOMEM;
 111
 112         signal = action_to_string(action);
 113         if (!signal)
 114                 return -EINVAL;
 115
 116         if (attr) {
 117                 len = strlen(path);
 118                 len += strlen(attr->name) + 2;
 119                 attrpath = kmalloc(len, gfp_mask);
 120                 if (!attrpath)
 121                         goto exit;
 122                 sprintf(attrpath, "%s/%s", path, attr->name);
 123                 rc = send_uevent(signal, attrpath, NULL, gfp_mask);
 124                 kfree(attrpath);
 125         } else
 126                 rc = send_uevent(signal, path, NULL, gfp_mask);
 127
 128 exit:
 129         kfree(path);
 130         return rc;
 131 }
 132
 133 /**
 134  * kobject_uevent - notify userspace by sending event through netlink socket
 135  *
 136  * @signal: signal name
 137  * @kobj: struct kobject that the event is happening to
 138  * @attr: optional struct attribute the event belongs to
 139  */
 140 int kobject_uevent(struct kobject *kobj, enum kobject_action action,
 141                    struct attribute *attr)
 142 {
 143         return do_kobject_uevent(kobj, action, attr, GFP_KERNEL);
 144 }
 145 EXPORT_SYMBOL_GPL(kobject_uevent);
 146
 147 int kobject_uevent_atomic(struct kobject *kobj, enum kobject_action action,
 148                           struct attribute *attr)
 149 {
 150         return do_kobject_uevent(kobj, action, attr, GFP_ATOMIC);
 151 }
 152 EXPORT_SYMBOL_GPL(kobject_uevent_atomic);
 153
 154 static int __init kobject_uevent_init(void)
 155 {
 156         uevent_sock = netlink_kernel_create(NETLINK_KOBJECT_UEVENT, NULL);
 157
 158         if (!uevent_sock) {
 159                 printk(KERN_ERR
 160                        "kobject_uevent: unable to create netlink socket!\n");
 161                 return -ENODEV;
 162         }
 163
 164         return 0;
 165 }
 166
 167 postcore_initcall(kobject_uevent_init);
 168
 169 #else
 170 static inline int send_uevent(const char *signal, const char *obj,
 171                               char **envp, int gfp_mask)
 172 {
 173         return 0;
 174 }
 175
 176 #endif /* CONFIG_KOBJECT_UEVENT */
 177
 178
 179 #ifdef CONFIG_HOTPLUG
 180 char hotplug_path[HOTPLUG_PATH_LEN] = "/sbin/hotplug";
 181 u64 hotplug_seqnum;
 182 static DEFINE_SPINLOCK(sequence_lock);
 183
 184 /**
 185  * kobject_hotplug - notify userspace by executing /sbin/hotplug
 186  *
 187  * @action: action that is happening (usually "ADD" or "REMOVE")
 188  * @kobj: struct kobject that the action is happening to
 189  */
 190 void kobject_hotplug(struct kobject *kobj, enum kobject_action action)
 191 {
 192         char *argv [3];
 193         char **envp = NULL;
 194         char *buffer = NULL;
 195         char *seq_buff;
 196         char *scratch;
 197         int i = 0;
 198         int retval;
 199         char *kobj_path = NULL;
 200         char *name = NULL;
 201         char *action_string;
 202         u64 seq;
 203         struct kobject *top_kobj = kobj;
 204         struct kset *kset;
 205         static struct kset_hotplug_ops null_hotplug_ops;
 206         struct kset_hotplug_ops *hotplug_ops = &null_hotplug_ops;
 207
 208         /* If this kobj does not belong to a kset,
 209            try to find a parent that does. */
 210         if (!top_kobj->kset && top_kobj->parent) {
 211                 do {
 212                         top_kobj = top_kobj->parent;
 213                 } while (!top_kobj->kset && top_kobj->parent);
 214         }
 215
 216         if (top_kobj->kset)
 217                 kset = top_kobj->kset;
 218         else
 219                 return;
 220
 221         if (kset->hotplug_ops)
 222                 hotplug_ops = kset->hotplug_ops;
 223
 224         /* If the kset has a filter operation, call it.
 225            Skip the event, if the filter returns zero. */
 226         if (hotplug_ops->filter) {
 227                 if (!hotplug_ops->filter(kset, kobj))
 228                         return;
 229         }
 230
 231         pr_debug ("%s\n", __FUNCTION__);
 232
 233         action_string = action_to_string(action);
 234         if (!action_string)
 235                 return;
 236
 237         envp = kmalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
 238         if (!envp)
 239                 return;
 240         memset (envp, 0x00, NUM_ENVP * sizeof (char *));
 241
 242         buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
 243         if (!buffer)
 244                 goto exit;
 245
 246         if (hotplug_ops->name)
 247                 name = hotplug_ops->name(kset, kobj);
 248         if (name == NULL)
 249                 name = kset->kobj.name;
 250
 251         argv [0] = hotplug_path;
 252         argv [1] = name;
 253         argv [2] = NULL;
 254
 255         /* minimal command environment */
 256         envp [i++] = "HOME=/";
 257         envp [i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 258
 259         scratch = buffer;
 260
 261         envp [i++] = scratch;
 262         scratch += sprintf(scratch, "ACTION=%s", action_string) + 1;
 263
 264         kobj_path = kobject_get_path(kobj, GFP_KERNEL);
 265         if (!kobj_path)
 266                 goto exit;
 267
 268         envp [i++] = scratch;
 269         scratch += sprintf (scratch, "DEVPATH=%s", kobj_path) + 1;
 270
 271         envp [i++] = scratch;
 272         scratch += sprintf(scratch, "SUBSYSTEM=%s", name) + 1;
 273
 274         /* reserve space for the sequence,
 275          * put the real one in after the hotplug call */
 276         envp[i++] = seq_buff = scratch;
 277         scratch += strlen("SEQNUM=18446744073709551616") + 1;
 278
 279         if (hotplug_ops->hotplug) {
 280                 /* have the kset specific function add its stuff */
 281                 retval = hotplug_ops->hotplug (kset, kobj,
 282                                   &envp[i], NUM_ENVP - i, scratch,
 283                                   BUFFER_SIZE - (scratch - buffer));
 284                 if (retval) {
 285                         pr_debug ("%s - hotplug() returned %d\n",
 286                                   __FUNCTION__, retval);
 287                         goto exit;
 288                 }
 289         }
 290
 291         spin_lock(&sequence_lock);
 292         seq = ++hotplug_seqnum;
 293         spin_unlock(&sequence_lock);
 294         sprintf(seq_buff, "SEQNUM=%llu", (unsigned long long)seq);
 295
 296         pr_debug ("%s: %s %s seq=%llu %s %s %s %s %s\n",
 297                   __FUNCTION__, argv[0], argv[1], (unsigned long long)seq,
 298                   envp[0], envp[1], envp[2], envp[3], envp[4]);
 299
 300         send_uevent(action_string, kobj_path, envp, GFP_KERNEL);
 301
 302         if (!hotplug_path[0])
 303                 goto exit;
 304
 305         retval = call_usermodehelper (argv[0], argv, envp, 0);
 306         if (retval)
 307                 pr_debug ("%s - call_usermodehelper returned %d\n",
 308                           __FUNCTION__, retval);
 309
 310 exit:
 311         kfree(kobj_path);
 312         kfree(buffer);
 313         kfree(envp);
 314         return;
 315 }
 316 EXPORT_SYMBOL(kobject_hotplug);
 317
 318 /**
 319  * add_hotplug_env_var - helper for creating hotplug environment variables
 320  * @envp: Pointer to table of environment variables, as passed into
 321  * hotplug() method.
 322  * @num_envp: Number of environment variable slots available, as
 323  * passed into hotplug() method.
 324  * @cur_index: Pointer to current index into @envp.  It should be
 325  * initialized to 0 before the first call to add_hotplug_env_var(),
 326  * and will be incremented on success.
 327  * @buffer: Pointer to buffer for environment variables, as passed
 328  * into hotplug() method.
 329  * @buffer_size: Length of @buffer, as passed into hotplug() method.
 330  * @cur_len: Pointer to current length of space used in @buffer.
 331  * Should be initialized to 0 before the first call to
 332  * add_hotplug_env_var(), and will be incremented on success.
 333  * @format: Format for creating environment variable (of the form
 334  * "XXX=%x") for snprintf().
 335  *
 336  * Returns 0 if environment variable was added successfully or -ENOMEM
 337  * if no space was available.
 338  */
 339 int add_hotplug_env_var(char **envp, int num_envp, int *cur_index,
 340                         char *buffer, int buffer_size, int *cur_len,
 341                         const char *format, ...)
 342 {
 343         va_list args;
 344
 345         /*
 346          * We check against num_envp - 1 to make sure there is at
 347          * least one slot left after we return, since the hotplug
 348          * method needs to set the last slot to NULL.
 349          */
 350         if (*cur_index >= num_envp - 1)
 351                 return -ENOMEM;
 352
 353         envp[*cur_index] = buffer + *cur_len;
 354
 355         va_start(args, format);
 356         *cur_len += vsnprintf(envp[*cur_index],
 357                               max(buffer_size - *cur_len, 0),
 358                               format, args) + 1;
 359         va_end(args);
 360
 361         if (*cur_len > buffer_size)
 362                 return -ENOMEM;
 363
 364         (*cur_index)++;
 365         return 0;
 366 }
 367 EXPORT_SYMBOL(add_hotplug_env_var);
 368
 369 #endif /* CONFIG_HOTPLUG */