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 u64 uevent_seqnum;
  30 char uevent_helper[UEVENT_HELPER_PATH_LEN] = "/sbin/hotplug";
  31 static DEFINE_SPINLOCK(sequence_lock);
  32 static struct sock *uevent_sock;
  33
  34 static char *action_to_string(enum kobject_action action)
  35 {
  36         switch (action) {
  37         case KOBJ_ADD:
  38                 return "add";
  39         case KOBJ_REMOVE:
  40                 return "remove";
  41         case KOBJ_CHANGE:
  42                 return "change";
  43         case KOBJ_MOUNT:
  44                 return "mount";
  45         case KOBJ_UMOUNT:
  46                 return "umount";
  47         case KOBJ_OFFLINE:
  48                 return "offline";
  49         case KOBJ_ONLINE:
  50                 return "online";
  51         default:
  52                 return NULL;
  53         }
  54 }
  55
  56 /**
  57  * kobject_uevent - notify userspace by ending an uevent
  58  *
  59  * @action: action that is happening (usually KOBJ_ADD and KOBJ_REMOVE)
  60  * @kobj: struct kobject that the action is happening to
  61  */
  62 void kobject_uevent(struct kobject *kobj, enum kobject_action action)
  63 {
  64         char **envp;
  65         char *buffer;
  66         char *scratch;
  67         const char *action_string;
  68         const char *devpath = NULL;
  69         const char *subsystem;
  70         struct kobject *top_kobj;
  71         struct kset *kset;
  72         struct kset_uevent_ops *uevent_ops;
  73         u64 seq;
  74         char *seq_buff;
  75         int i = 0;
  76         int retval;
  77
  78         pr_debug("%s\n", __FUNCTION__);
  79
  80         action_string = action_to_string(action);
  81         if (!action_string)
  82                 return;
  83
  84         /* search the kset we belong to */
  85         top_kobj = kobj;
  86         if (!top_kobj->kset && top_kobj->parent) {
  87                 do {
  88                         top_kobj = top_kobj->parent;
  89                 } while (!top_kobj->kset && top_kobj->parent);
  90         }
  91         if (!top_kobj->kset)
  92                 return;
  93
  94         kset = top_kobj->kset;
  95         uevent_ops = kset->uevent_ops;
  96
  97         /*  skip the event, if the filter returns zero. */
  98         if (uevent_ops && uevent_ops->filter)
  99                 if (!uevent_ops->filter(kset, kobj))
 100                         return;
 101
 102         /* environment index */
 103         envp = kzalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
 104         if (!envp)
 105                 return;
 106
 107         /* environment values */
 108         buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
 109         if (!buffer)
 110                 goto exit;
 111
 112         /* complete object path */
 113         devpath = kobject_get_path(kobj, GFP_KERNEL);
 114         if (!devpath)
 115                 goto exit;
 116
 117         /* originating subsystem */
 118         if (uevent_ops && uevent_ops->name)
 119                 subsystem = uevent_ops->name(kset, kobj);
 120         else
 121                 subsystem = kobject_name(&kset->kobj);
 122
 123         /* event environemnt for helper process only */
 124         envp[i++] = "HOME=/";
 125         envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 126
 127         /* default keys */
 128         scratch = buffer;
 129         envp [i++] = scratch;
 130         scratch += sprintf(scratch, "ACTION=%s", action_string) + 1;
 131         envp [i++] = scratch;
 132         scratch += sprintf (scratch, "DEVPATH=%s", devpath) + 1;
 133         envp [i++] = scratch;
 134         scratch += sprintf(scratch, "SUBSYSTEM=%s", subsystem) + 1;
 135
 136         /* just reserve the space, overwrite it after kset call has returned */
 137         envp[i++] = seq_buff = scratch;
 138         scratch += strlen("SEQNUM=18446744073709551616") + 1;
 139
 140         /* let the kset specific function add its stuff */
 141         if (uevent_ops && uevent_ops->uevent) {
 142                 retval = uevent_ops->uevent(kset, kobj,
 143                                   &envp[i], NUM_ENVP - i, scratch,
 144                                   BUFFER_SIZE - (scratch - buffer));
 145                 if (retval) {
 146                         pr_debug ("%s - uevent() returned %d\n",
 147                                   __FUNCTION__, retval);
 148                         goto exit;
 149                 }
 150         }
 151
 152         /* we will send an event, request a new sequence number */
 153         spin_lock(&sequence_lock);
 154         seq = ++uevent_seqnum;
 155         spin_unlock(&sequence_lock);
 156         sprintf(seq_buff, "SEQNUM=%llu", (unsigned long long)seq);
 157
 158         /* send netlink message */
 159         if (uevent_sock) {
 160                 struct sk_buff *skb;
 161                 size_t len;
 162
 163                 /* allocate message with the maximum possible size */
 164                 len = strlen(action_string) + strlen(devpath) + 2;
 165                 skb = alloc_skb(len + BUFFER_SIZE, GFP_KERNEL);
 166                 if (skb) {
 167                         /* add header */
 168                         scratch = skb_put(skb, len);
 169                         sprintf(scratch, "%s@%s", action_string, devpath);
 170
 171                         /* copy keys to our continuous event payload buffer */
 172                         for (i = 2; envp[i]; i++) {
 173                                 len = strlen(envp[i]) + 1;
 174                                 scratch = skb_put(skb, len);
 175                                 strcpy(scratch, envp[i]);
 176                         }
 177
 178                         NETLINK_CB(skb).dst_group = 1;
 179                         netlink_broadcast(uevent_sock, skb, 0, 1, GFP_KERNEL);
 180                 }
 181         }
 182
 183         /* call uevent_helper, usually only enabled during early boot */
 184         if (uevent_helper[0]) {
 185                 char *argv [3];
 186
 187                 argv [0] = uevent_helper;
 188                 argv [1] = (char *)subsystem;
 189                 argv [2] = NULL;
 190                 call_usermodehelper (argv[0], argv, envp, 0);
 191         }
 192
 193 exit:
 194         kfree(devpath);
 195         kfree(buffer);
 196         kfree(envp);
 197         return;
 198 }
 199 EXPORT_SYMBOL_GPL(kobject_uevent);
 200
 201 /**
 202  * add_uevent_var - helper for creating event variables
 203  * @envp: Pointer to table of environment variables, as passed into
 204  * uevent() method.
 205  * @num_envp: Number of environment variable slots available, as
 206  * passed into uevent() method.
 207  * @cur_index: Pointer to current index into @envp.  It should be
 208  * initialized to 0 before the first call to add_uevent_var(),
 209  * and will be incremented on success.
 210  * @buffer: Pointer to buffer for environment variables, as passed
 211  * into uevent() method.
 212  * @buffer_size: Length of @buffer, as passed into uevent() method.
 213  * @cur_len: Pointer to current length of space used in @buffer.
 214  * Should be initialized to 0 before the first call to
 215  * add_uevent_var(), and will be incremented on success.
 216  * @format: Format for creating environment variable (of the form
 217  * "XXX=%x") for snprintf().
 218  *
 219  * Returns 0 if environment variable was added successfully or -ENOMEM
 220  * if no space was available.
 221  */
 222 int add_uevent_var(char **envp, int num_envp, int *cur_index,
 223                    char *buffer, int buffer_size, int *cur_len,
 224                    const char *format, ...)
 225 {
 226         va_list args;
 227
 228         /*
 229          * We check against num_envp - 1 to make sure there is at
 230          * least one slot left after we return, since kobject_uevent()
 231          * needs to set the last slot to NULL.
 232          */
 233         if (*cur_index >= num_envp - 1)
 234                 return -ENOMEM;
 235
 236         envp[*cur_index] = buffer + *cur_len;
 237
 238         va_start(args, format);
 239         *cur_len += vsnprintf(envp[*cur_index],
 240                               max(buffer_size - *cur_len, 0),
 241                               format, args) + 1;
 242         va_end(args);
 243
 244         if (*cur_len > buffer_size)
 245                 return -ENOMEM;
 246
 247         (*cur_index)++;
 248         return 0;
 249 }
 250 EXPORT_SYMBOL_GPL(add_uevent_var);
 251
 252 static int __init kobject_uevent_init(void)
 253 {
 254         uevent_sock = netlink_kernel_create(NETLINK_KOBJECT_UEVENT, 1, NULL,
 255                                             THIS_MODULE);
 256
 257         if (!uevent_sock) {
 258                 printk(KERN_ERR
 259                        "kobject_uevent: unable to create netlink socket!\n");
 260                 return -ENODEV;
 261         }
 262
 263         return 0;
 264 }
 265
 266 postcore_initcall(kobject_uevent_init);
 267
 268 #endif /* CONFIG_HOTPLUG */