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)
  29 u64 uevent_seqnum;
  30 char uevent_helper[UEVENT_HELPER_PATH_LEN] = "/sbin/hotplug";
  31 static DEFINE_SPINLOCK(sequence_lock);
  32 #if defined(CONFIG_NET)
  33 static struct sock *uevent_sock;
  34 #endif
  35
  36 static char *action_to_string(enum kobject_action action)
  37 {
  38         switch (action) {
  39         case KOBJ_ADD:
  40                 return "add";
  41         case KOBJ_REMOVE:
  42                 return "remove";
  43         case KOBJ_CHANGE:
  44                 return "change";
  45         case KOBJ_MOUNT:
  46                 return "mount";
  47         case KOBJ_UMOUNT:
  48                 return "umount";
  49         case KOBJ_OFFLINE:
  50                 return "offline";
  51         case KOBJ_ONLINE:
  52                 return "online";
  53         case KOBJ_DOCK:
  54                 return "dock";
  55         case KOBJ_UNDOCK:
  56                 return "undock";
  57         default:
  58                 return NULL;
  59         }
  60 }
  61
  62 /**
  63  * kobject_uevent - notify userspace by ending an uevent
  64  *
  65  * @action: action that is happening (usually KOBJ_ADD and KOBJ_REMOVE)
  66  * @kobj: struct kobject that the action is happening to
  67  */
  68 void kobject_uevent(struct kobject *kobj, enum kobject_action action)
  69 {
  70         char **envp;
  71         char *buffer;
  72         char *scratch;
  73         const char *action_string;
  74         const char *devpath = NULL;
  75         const char *subsystem;
  76         struct kobject *top_kobj;
  77         struct kset *kset;
  78         struct kset_uevent_ops *uevent_ops;
  79         u64 seq;
  80         char *seq_buff;
  81         int i = 0;
  82         int retval;
  83
  84         pr_debug("%s\n", __FUNCTION__);
  85
  86         action_string = action_to_string(action);
  87         if (!action_string)
  88                 return;
  89
  90         /* search the kset we belong to */
  91         top_kobj = kobj;
  92         if (!top_kobj->kset && top_kobj->parent) {
  93                 do {
  94                         top_kobj = top_kobj->parent;
  95                 } while (!top_kobj->kset && top_kobj->parent);
  96         }
  97         if (!top_kobj->kset)
  98                 return;
  99
 100         kset = top_kobj->kset;
 101         uevent_ops = kset->uevent_ops;
 102
 103         /*  skip the event, if the filter returns zero. */
 104         if (uevent_ops && uevent_ops->filter)
 105                 if (!uevent_ops->filter(kset, kobj))
 106                         return;
 107
 108         /* environment index */
 109         envp = kzalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
 110         if (!envp)
 111                 return;
 112
 113         /* environment values */
 114         buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
 115         if (!buffer)
 116                 goto exit;
 117
 118         /* complete object path */
 119         devpath = kobject_get_path(kobj, GFP_KERNEL);
 120         if (!devpath)
 121                 goto exit;
 122
 123         /* originating subsystem */
 124         if (uevent_ops && uevent_ops->name)
 125                 subsystem = uevent_ops->name(kset, kobj);
 126         else
 127                 subsystem = kobject_name(&kset->kobj);
 128
 129         /* event environemnt for helper process only */
 130         envp[i++] = "HOME=/";
 131         envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 132
 133         /* default keys */
 134         scratch = buffer;
 135         envp [i++] = scratch;
 136         scratch += sprintf(scratch, "ACTION=%s", action_string) + 1;
 137         envp [i++] = scratch;
 138         scratch += sprintf (scratch, "DEVPATH=%s", devpath) + 1;
 139         envp [i++] = scratch;
 140         scratch += sprintf(scratch, "SUBSYSTEM=%s", subsystem) + 1;
 141
 142         /* just reserve the space, overwrite it after kset call has returned */
 143         envp[i++] = seq_buff = scratch;
 144         scratch += strlen("SEQNUM=18446744073709551616") + 1;
 145
 146         /* let the kset specific function add its stuff */
 147         if (uevent_ops && uevent_ops->uevent) {
 148                 retval = uevent_ops->uevent(kset, kobj,
 149                                   &envp[i], NUM_ENVP - i, scratch,
 150                                   BUFFER_SIZE - (scratch - buffer));
 151                 if (retval) {
 152                         pr_debug ("%s - uevent() returned %d\n",
 153                                   __FUNCTION__, retval);
 154                         goto exit;
 155                 }
 156         }
 157
 158         /* we will send an event, request a new sequence number */
 159         spin_lock(&sequence_lock);
 160         seq = ++uevent_seqnum;
 161         spin_unlock(&sequence_lock);
 162         sprintf(seq_buff, "SEQNUM=%llu", (unsigned long long)seq);
 163
 164 #if defined(CONFIG_NET)
 165         /* send netlink message */
 166         if (uevent_sock) {
 167                 struct sk_buff *skb;
 168                 size_t len;
 169
 170                 /* allocate message with the maximum possible size */
 171                 len = strlen(action_string) + strlen(devpath) + 2;
 172                 skb = alloc_skb(len + BUFFER_SIZE, GFP_KERNEL);
 173                 if (skb) {
 174                         /* add header */
 175                         scratch = skb_put(skb, len);
 176                         sprintf(scratch, "%s@%s", action_string, devpath);
 177
 178                         /* copy keys to our continuous event payload buffer */
 179                         for (i = 2; envp[i]; i++) {
 180                                 len = strlen(envp[i]) + 1;
 181                                 scratch = skb_put(skb, len);
 182                                 strcpy(scratch, envp[i]);
 183                         }
 184
 185                         NETLINK_CB(skb).dst_group = 1;
 186                         netlink_broadcast(uevent_sock, skb, 0, 1, GFP_KERNEL);
 187                 }
 188         }
 189 #endif
 190
 191         /* call uevent_helper, usually only enabled during early boot */
 192         if (uevent_helper[0]) {
 193                 char *argv [3];
 194
 195                 argv [0] = uevent_helper;
 196                 argv [1] = (char *)subsystem;
 197                 argv [2] = NULL;
 198                 call_usermodehelper (argv[0], argv, envp, 0);
 199         }
 200
 201 exit:
 202         kfree(devpath);
 203         kfree(buffer);
 204         kfree(envp);
 205         return;
 206 }
 207 EXPORT_SYMBOL_GPL(kobject_uevent);
 208
 209 /**
 210  * add_uevent_var - helper for creating event variables
 211  * @envp: Pointer to table of environment variables, as passed into
 212  * uevent() method.
 213  * @num_envp: Number of environment variable slots available, as
 214  * passed into uevent() method.
 215  * @cur_index: Pointer to current index into @envp.  It should be
 216  * initialized to 0 before the first call to add_uevent_var(),
 217  * and will be incremented on success.
 218  * @buffer: Pointer to buffer for environment variables, as passed
 219  * into uevent() method.
 220  * @buffer_size: Length of @buffer, as passed into uevent() method.
 221  * @cur_len: Pointer to current length of space used in @buffer.
 222  * Should be initialized to 0 before the first call to
 223  * add_uevent_var(), and will be incremented on success.
 224  * @format: Format for creating environment variable (of the form
 225  * "XXX=%x") for snprintf().
 226  *
 227  * Returns 0 if environment variable was added successfully or -ENOMEM
 228  * if no space was available.
 229  */
 230 int add_uevent_var(char **envp, int num_envp, int *cur_index,
 231                    char *buffer, int buffer_size, int *cur_len,
 232                    const char *format, ...)
 233 {
 234         va_list args;
 235
 236         /*
 237          * We check against num_envp - 1 to make sure there is at
 238          * least one slot left after we return, since kobject_uevent()
 239          * needs to set the last slot to NULL.
 240          */
 241         if (*cur_index >= num_envp - 1)
 242                 return -ENOMEM;
 243
 244         envp[*cur_index] = buffer + *cur_len;
 245
 246         va_start(args, format);
 247         *cur_len += vsnprintf(envp[*cur_index],
 248                               max(buffer_size - *cur_len, 0),
 249                               format, args) + 1;
 250         va_end(args);
 251
 252         if (*cur_len > buffer_size)
 253                 return -ENOMEM;
 254
 255         (*cur_index)++;
 256         return 0;
 257 }
 258 EXPORT_SYMBOL_GPL(add_uevent_var);
 259
 260 #if defined(CONFIG_NET)
 261 static int __init kobject_uevent_init(void)
 262 {
 263         uevent_sock = netlink_kernel_create(NETLINK_KOBJECT_UEVENT, 1, NULL,
 264                                             THIS_MODULE);
 265
 266         if (!uevent_sock) {
 267                 printk(KERN_ERR
 268                        "kobject_uevent: unable to create netlink socket!\n");
 269                 return -ENODEV;
 270         }
 271
 272         return 0;
 273 }
 274
 275 postcore_initcall(kobject_uevent_init);
 276 #endif
 277
 278 #endif /* CONFIG_HOTPLUG */