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) && defined(CONFIG_NET)
  29 static DEFINE_SPINLOCK(sequence_lock);
  30 static struct sock *uevent_sock;
  31
  32 static char *action_to_string(enum kobject_action action)
  33 {
  34         switch (action) {
  35         case KOBJ_ADD:
  36                 return "add";
  37         case KOBJ_REMOVE:
  38                 return "remove";
  39         case KOBJ_CHANGE:
  40                 return "change";
  41         case KOBJ_MOUNT:
  42                 return "mount";
  43         case KOBJ_UMOUNT:
  44                 return "umount";
  45         case KOBJ_OFFLINE:
  46                 return "offline";
  47         case KOBJ_ONLINE:
  48                 return "online";
  49         default:
  50                 return NULL;
  51         }
  52 }
  53
  54 /**
  55  * kobject_uevent - notify userspace by ending an uevent
  56  *
  57  * @action: action that is happening (usually KOBJ_ADD and KOBJ_REMOVE)
  58  * @kobj: struct kobject that the action is happening to
  59  */
  60 void kobject_uevent(struct kobject *kobj, enum kobject_action action)
  61 {
  62         char **envp;
  63         char *buffer;
  64         char *scratch;
  65         const char *action_string;
  66         const char *devpath = NULL;
  67         const char *subsystem;
  68         struct kobject *top_kobj;
  69         struct kset *kset;
  70         struct kset_uevent_ops *uevent_ops;
  71         u64 seq;
  72         char *seq_buff;
  73         int i = 0;
  74         int retval;
  75
  76         pr_debug("%s\n", __FUNCTION__);
  77
  78         action_string = action_to_string(action);
  79         if (!action_string)
  80                 return;
  81
  82         /* search the kset we belong to */
  83         top_kobj = kobj;
  84         if (!top_kobj->kset && top_kobj->parent) {
  85                 do {
  86                         top_kobj = top_kobj->parent;
  87                 } while (!top_kobj->kset && top_kobj->parent);
  88         }
  89         if (!top_kobj->kset)
  90                 return;
  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                         return;
  99
 100         /* environment index */
 101         envp = kzalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
 102         if (!envp)
 103                 return;
 104
 105         /* environment values */
 106         buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
 107         if (!buffer)
 108                 goto exit;
 109
 110         /* complete object path */
 111         devpath = kobject_get_path(kobj, GFP_KERNEL);
 112         if (!devpath)
 113                 goto exit;
 114
 115         /* originating subsystem */
 116         if (uevent_ops && uevent_ops->name)
 117                 subsystem = uevent_ops->name(kset, kobj);
 118         else
 119                 subsystem = kobject_name(&kset->kobj);
 120
 121         /* event environemnt for helper process only */
 122         envp[i++] = "HOME=/";
 123         envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 124
 125         /* default keys */
 126         scratch = buffer;
 127         envp [i++] = scratch;
 128         scratch += sprintf(scratch, "ACTION=%s", action_string) + 1;
 129         envp [i++] = scratch;
 130         scratch += sprintf (scratch, "DEVPATH=%s", devpath) + 1;
 131         envp [i++] = scratch;
 132         scratch += sprintf(scratch, "SUBSYSTEM=%s", subsystem) + 1;
 133
 134         /* just reserve the space, overwrite it after kset call has returned */
 135         envp[i++] = seq_buff = scratch;
 136         scratch += strlen("SEQNUM=18446744073709551616") + 1;
 137
 138         /* let the kset specific function add its stuff */
 139         if (uevent_ops && uevent_ops->uevent) {
 140                 retval = uevent_ops->uevent(kset, kobj,
 141                                   &envp[i], NUM_ENVP - i, scratch,
 142                                   BUFFER_SIZE - (scratch - buffer));
 143                 if (retval) {
 144                         pr_debug ("%s - uevent() returned %d\n",
 145                                   __FUNCTION__, retval);
 146                         goto exit;
 147                 }
 148         }
 149
 150         /* we will send an event, request a new sequence number */
 151         spin_lock(&sequence_lock);
 152         seq = ++uevent_seqnum;
 153         spin_unlock(&sequence_lock);
 154         sprintf(seq_buff, "SEQNUM=%llu", (unsigned long long)seq);
 155
 156         /* send netlink message */
 157         if (uevent_sock) {
 158                 struct sk_buff *skb;
 159                 size_t len;
 160
 161                 /* allocate message with the maximum possible size */
 162                 len = strlen(action_string) + strlen(devpath) + 2;
 163                 skb = alloc_skb(len + BUFFER_SIZE, GFP_KERNEL);
 164                 if (skb) {
 165                         /* add header */
 166                         scratch = skb_put(skb, len);
 167                         sprintf(scratch, "%s@%s", action_string, devpath);
 168
 169                         /* copy keys to our continuous event payload buffer */
 170                         for (i = 2; envp[i]; i++) {
 171                                 len = strlen(envp[i]) + 1;
 172                                 scratch = skb_put(skb, len);
 173                                 strcpy(scratch, envp[i]);
 174                         }
 175
 176                         NETLINK_CB(skb).dst_group = 1;
 177                         netlink_broadcast(uevent_sock, skb, 0, 1, GFP_KERNEL);
 178                 }
 179         }
 180
 181         /* call uevent_helper, usually only enabled during early boot */
 182         if (uevent_helper[0]) {
 183                 char *argv [3];
 184
 185                 argv [0] = uevent_helper;
 186                 argv [1] = (char *)subsystem;
 187                 argv [2] = NULL;
 188                 call_usermodehelper (argv[0], argv, envp, 0);
 189         }
 190
 191 exit:
 192         kfree(devpath);
 193         kfree(buffer);
 194         kfree(envp);
 195         return;
 196 }
 197 EXPORT_SYMBOL_GPL(kobject_uevent);
 198
 199 /**
 200  * add_uevent_var - helper for creating event variables
 201  * @envp: Pointer to table of environment variables, as passed into
 202  * uevent() method.
 203  * @num_envp: Number of environment variable slots available, as
 204  * passed into uevent() method.
 205  * @cur_index: Pointer to current index into @envp.  It should be
 206  * initialized to 0 before the first call to add_uevent_var(),
 207  * and will be incremented on success.
 208  * @buffer: Pointer to buffer for environment variables, as passed
 209  * into uevent() method.
 210  * @buffer_size: Length of @buffer, as passed into uevent() method.
 211  * @cur_len: Pointer to current length of space used in @buffer.
 212  * Should be initialized to 0 before the first call to
 213  * add_uevent_var(), and will be incremented on success.
 214  * @format: Format for creating environment variable (of the form
 215  * "XXX=%x") for snprintf().
 216  *
 217  * Returns 0 if environment variable was added successfully or -ENOMEM
 218  * if no space was available.
 219  */
 220 int add_uevent_var(char **envp, int num_envp, int *cur_index,
 221                    char *buffer, int buffer_size, int *cur_len,
 222                    const char *format, ...)
 223 {
 224         va_list args;
 225
 226         /*
 227          * We check against num_envp - 1 to make sure there is at
 228          * least one slot left after we return, since kobject_uevent()
 229          * needs to set the last slot to NULL.
 230          */
 231         if (*cur_index >= num_envp - 1)
 232                 return -ENOMEM;
 233
 234         envp[*cur_index] = buffer + *cur_len;
 235
 236         va_start(args, format);
 237         *cur_len += vsnprintf(envp[*cur_index],
 238                               max(buffer_size - *cur_len, 0),
 239                               format, args) + 1;
 240         va_end(args);
 241
 242         if (*cur_len > buffer_size)
 243                 return -ENOMEM;
 244
 245         (*cur_index)++;
 246         return 0;
 247 }
 248 EXPORT_SYMBOL_GPL(add_uevent_var);
 249
 250 static int __init kobject_uevent_init(void)
 251 {
 252         uevent_sock = netlink_kernel_create(NETLINK_KOBJECT_UEVENT, 1, NULL,
 253                                             THIS_MODULE);
 254
 255         if (!uevent_sock) {
 256                 printk(KERN_ERR
 257                        "kobject_uevent: unable to create netlink socket!\n");
 258                 return -ENODEV;
 259         }
 260
 261         return 0;
 262 }
 263
 264 postcore_initcall(kobject_uevent_init);
 265
 266 #endif /* CONFIG_HOTPLUG */