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