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