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