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/string.h>
  19 #include <linux/kobject.h>
  20 #include <linux/export.h>
  21 #include <linux/kmod.h>
  22 #include <linux/slab.h>
  23 #include <linux/socket.h>
  24 #include <linux/skbuff.h>
  25 #include <linux/netlink.h>
  26 #include <linux/uuid.h>
  27 #include <linux/ctype.h>
  28 #include <net/sock.h>
  29 #include <net/net_namespace.h>
  30
  31
  32 u64 uevent_seqnum;
  33 #ifdef CONFIG_UEVENT_HELPER
  34 char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
  35 #endif
  36 #ifdef CONFIG_NET
  37 struct uevent_sock {
  38         struct list_head list;
  39         struct sock *sk;
  40 };
  41 static LIST_HEAD(uevent_sock_list);
  42 #endif
  43
  44 /* This lock protects uevent_seqnum and uevent_sock_list */
  45 static DEFINE_MUTEX(uevent_sock_mutex);
  46
  47 /* the strings here must match the enum in include/linux/kobject.h */
  48 static const char *kobject_actions[] = {
  49         [KOBJ_ADD] =            "add",
  50         [KOBJ_REMOVE] =         "remove",
  51         [KOBJ_CHANGE] =         "change",
  52         [KOBJ_MOVE] =           "move",
  53         [KOBJ_ONLINE] =         "online",
  54         [KOBJ_OFFLINE] =        "offline",
  55 };
  56
  57 static int kobject_action_type(const char *buf, size_t count,
  58                                enum kobject_action *type,
  59                                const char **args)
  60 {
  61         enum kobject_action action;
  62         size_t count_first;
  63         const char *args_start;
  64         int ret = -EINVAL;
  65
  66         if (count && (buf[count-1] == '\n' || buf[count-1] == '\0'))
  67                 count--;
  68
  69         if (!count)
  70                 goto out;
  71
  72         args_start = strnchr(buf, count, ' ');
  73         if (args_start) {
  74                 count_first = args_start - buf;
  75                 args_start = args_start + 1;
  76         } else
  77                 count_first = count;
  78
  79         for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
  80                 if (strncmp(kobject_actions[action], buf, count_first) != 0)
  81                         continue;
  82                 if (kobject_actions[action][count_first] != '\0')
  83                         continue;
  84                 if (args)
  85                         *args = args_start;
  86                 *type = action;
  87                 ret = 0;
  88                 break;
  89         }
  90 out:
  91         return ret;
  92 }
  93
  94 static const char *action_arg_word_end(const char *buf, const char *buf_end,
  95                                        char delim)
  96 {
  97         const char *next = buf;
  98
  99         while (next <= buf_end && *next != delim)
 100                 if (!isalnum(*next++))
 101                         return NULL;
 102
 103         if (next == buf)
 104                 return NULL;
 105
 106         return next;
 107 }
 108
 109 static int kobject_action_args(const char *buf, size_t count,
 110                                struct kobj_uevent_env **ret_env)
 111 {
 112         struct kobj_uevent_env *env = NULL;
 113         const char *next, *buf_end, *key;
 114         int key_len;
 115         int r = -EINVAL;
 116
 117         if (count && (buf[count - 1] == '\n' || buf[count - 1] == '\0'))
 118                 count--;
 119
 120         if (!count)
 121                 return -EINVAL;
 122
 123         env = kzalloc(sizeof(*env), GFP_KERNEL);
 124         if (!env)
 125                 return -ENOMEM;
 126
 127         /* first arg is UUID */
 128         if (count < UUID_STRING_LEN || !uuid_is_valid(buf) ||
 129             add_uevent_var(env, "SYNTH_UUID=%.*s", UUID_STRING_LEN, buf))
 130                 goto out;
 131
 132         /*
 133          * the rest are custom environment variables in KEY=VALUE
 134          * format with ' ' delimiter between each KEY=VALUE pair
 135          */
 136         next = buf + UUID_STRING_LEN;
 137         buf_end = buf + count - 1;
 138
 139         while (next <= buf_end) {
 140                 if (*next != ' ')
 141                         goto out;
 142
 143                 /* skip the ' ', key must follow */
 144                 key = ++next;
 145                 if (key > buf_end)
 146                         goto out;
 147
 148                 buf = next;
 149                 next = action_arg_word_end(buf, buf_end, '=');
 150                 if (!next || next > buf_end || *next != '=')
 151                         goto out;
 152                 key_len = next - buf;
 153
 154                 /* skip the '=', value must follow */
 155                 if (++next > buf_end)
 156                         goto out;
 157
 158                 buf = next;
 159                 next = action_arg_word_end(buf, buf_end, ' ');
 160                 if (!next)
 161                         goto out;
 162
 163                 if (add_uevent_var(env, "SYNTH_ARG_%.*s=%.*s",
 164                                    key_len, key, (int) (next - buf), buf))
 165                         goto out;
 166         }
 167
 168         r = 0;
 169 out:
 170         if (r)
 171                 kfree(env);
 172         else
 173                 *ret_env = env;
 174         return r;
 175 }
 176
 177 /**
 178  * kobject_synth_uevent - send synthetic uevent with arguments
 179  *
 180  * @kobj: struct kobject for which synthetic uevent is to be generated
 181  * @buf: buffer containing action type and action args, newline is ignored
 182  * @count: length of buffer
 183  *
 184  * Returns 0 if kobject_synthetic_uevent() is completed with success or the
 185  * corresponding error when it fails.
 186  */
 187 int kobject_synth_uevent(struct kobject *kobj, const char *buf, size_t count)
 188 {
 189         char *no_uuid_envp[] = { "SYNTH_UUID=0", NULL };
 190         enum kobject_action action;
 191         const char *action_args;
 192         struct kobj_uevent_env *env;
 193         const char *msg = NULL, *devpath;
 194         int r;
 195
 196         r = kobject_action_type(buf, count, &action, &action_args);
 197         if (r) {
 198                 msg = "unknown uevent action string\n";
 199                 goto out;
 200         }
 201
 202         if (!action_args) {
 203                 r = kobject_uevent_env(kobj, action, no_uuid_envp);
 204                 goto out;
 205         }
 206
 207         r = kobject_action_args(action_args,
 208                                 count - (action_args - buf), &env);
 209         if (r == -EINVAL) {
 210                 msg = "incorrect uevent action arguments\n";
 211                 goto out;
 212         }
 213
 214         if (r)
 215                 goto out;
 216
 217         r = kobject_uevent_env(kobj, action, env->envp);
 218         kfree(env);
 219 out:
 220         if (r) {
 221                 devpath = kobject_get_path(kobj, GFP_KERNEL);
 222                 printk(KERN_WARNING "synth uevent: %s: %s",
 223                        devpath ?: "unknown device",
 224                        msg ?: "failed to send uevent");
 225                 kfree(devpath);
 226         }
 227         return r;
 228 }
 229
 230 #ifdef CONFIG_NET
 231 static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data)
 232 {
 233         struct kobject *kobj = data, *ksobj;
 234         const struct kobj_ns_type_operations *ops;
 235
 236         ops = kobj_ns_ops(kobj);
 237         if (!ops && kobj->kset) {
 238                 ksobj = &kobj->kset->kobj;
 239                 if (ksobj->parent != NULL)
 240                         ops = kobj_ns_ops(ksobj->parent);
 241         }
 242
 243         if (ops && ops->netlink_ns && kobj->ktype->namespace) {
 244                 const void *sock_ns, *ns;
 245                 ns = kobj->ktype->namespace(kobj);
 246                 sock_ns = ops->netlink_ns(dsk);
 247                 return sock_ns != ns;
 248         }
 249
 250         return 0;
 251 }
 252 #endif
 253
 254 #ifdef CONFIG_UEVENT_HELPER
 255 static int kobj_usermode_filter(struct kobject *kobj)
 256 {
 257         const struct kobj_ns_type_operations *ops;
 258
 259         ops = kobj_ns_ops(kobj);
 260         if (ops) {
 261                 const void *init_ns, *ns;
 262                 ns = kobj->ktype->namespace(kobj);
 263                 init_ns = ops->initial_ns();
 264                 return ns != init_ns;
 265         }
 266
 267         return 0;
 268 }
 269
 270 static int init_uevent_argv(struct kobj_uevent_env *env, const char *subsystem)
 271 {
 272         int len;
 273
 274         len = strlcpy(&env->buf[env->buflen], subsystem,
 275                       sizeof(env->buf) - env->buflen);
 276         if (len >= (sizeof(env->buf) - env->buflen)) {
 277                 WARN(1, KERN_ERR "init_uevent_argv: buffer size too small\n");
 278                 return -ENOMEM;
 279         }
 280
 281         env->argv[0] = uevent_helper;
 282         env->argv[1] = &env->buf[env->buflen];
 283         env->argv[2] = NULL;
 284
 285         env->buflen += len + 1;
 286         return 0;
 287 }
 288
 289 static void cleanup_uevent_env(struct subprocess_info *info)
 290 {
 291         kfree(info->data);
 292 }
 293 #endif
 294
 295 /**
 296  * kobject_uevent_env - send an uevent with environmental data
 297  *
 298  * @kobj: struct kobject that the action is happening to
 299  * @action: action that is happening
 300  * @envp_ext: pointer to environmental data
 301  *
 302  * Returns 0 if kobject_uevent_env() is completed with success or the
 303  * corresponding error when it fails.
 304  */
 305 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
 306                        char *envp_ext[])
 307 {
 308         struct kobj_uevent_env *env;
 309         const char *action_string = kobject_actions[action];
 310         const char *devpath = NULL;
 311         const char *subsystem;
 312         struct kobject *top_kobj;
 313         struct kset *kset;
 314         const struct kset_uevent_ops *uevent_ops;
 315         int i = 0;
 316         int retval = 0;
 317 #ifdef CONFIG_NET
 318         struct uevent_sock *ue_sk;
 319 #endif
 320
 321         pr_debug("kobject: '%s' (%p): %s\n",
 322                  kobject_name(kobj), kobj, __func__);
 323
 324         /* search the kset we belong to */
 325         top_kobj = kobj;
 326         while (!top_kobj->kset && top_kobj->parent)
 327                 top_kobj = top_kobj->parent;
 328
 329         if (!top_kobj->kset) {
 330                 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
 331                          "without kset!\n", kobject_name(kobj), kobj,
 332                          __func__);
 333                 return -EINVAL;
 334         }
 335
 336         kset = top_kobj->kset;
 337         uevent_ops = kset->uevent_ops;
 338
 339         /* skip the event, if uevent_suppress is set*/
 340         if (kobj->uevent_suppress) {
 341                 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
 342                                  "caused the event to drop!\n",
 343                                  kobject_name(kobj), kobj, __func__);
 344                 return 0;
 345         }
 346         /* skip the event, if the filter returns zero. */
 347         if (uevent_ops && uevent_ops->filter)
 348                 if (!uevent_ops->filter(kset, kobj)) {
 349                         pr_debug("kobject: '%s' (%p): %s: filter function "
 350                                  "caused the event to drop!\n",
 351                                  kobject_name(kobj), kobj, __func__);
 352                         return 0;
 353                 }
 354
 355         /* originating subsystem */
 356         if (uevent_ops && uevent_ops->name)
 357                 subsystem = uevent_ops->name(kset, kobj);
 358         else
 359                 subsystem = kobject_name(&kset->kobj);
 360         if (!subsystem) {
 361                 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
 362                          "event to drop!\n", kobject_name(kobj), kobj,
 363                          __func__);
 364                 return 0;
 365         }
 366
 367         /* environment buffer */
 368         env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
 369         if (!env)
 370                 return -ENOMEM;
 371
 372         /* complete object path */
 373         devpath = kobject_get_path(kobj, GFP_KERNEL);
 374         if (!devpath) {
 375                 retval = -ENOENT;
 376                 goto exit;
 377         }
 378
 379         /* default keys */
 380         retval = add_uevent_var(env, "ACTION=%s", action_string);
 381         if (retval)
 382                 goto exit;
 383         retval = add_uevent_var(env, "DEVPATH=%s", devpath);
 384         if (retval)
 385                 goto exit;
 386         retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
 387         if (retval)
 388                 goto exit;
 389
 390         /* keys passed in from the caller */
 391         if (envp_ext) {
 392                 for (i = 0; envp_ext[i]; i++) {
 393                         retval = add_uevent_var(env, "%s", envp_ext[i]);
 394                         if (retval)
 395                                 goto exit;
 396                 }
 397         }
 398
 399         /* let the kset specific function add its stuff */
 400         if (uevent_ops && uevent_ops->uevent) {
 401                 retval = uevent_ops->uevent(kset, kobj, env);
 402                 if (retval) {
 403                         pr_debug("kobject: '%s' (%p): %s: uevent() returned "
 404                                  "%d\n", kobject_name(kobj), kobj,
 405                                  __func__, retval);
 406                         goto exit;
 407                 }
 408         }
 409
 410         /*
 411          * Mark "add" and "remove" events in the object to ensure proper
 412          * events to userspace during automatic cleanup. If the object did
 413          * send an "add" event, "remove" will automatically generated by
 414          * the core, if not already done by the caller.
 415          */
 416         if (action == KOBJ_ADD)
 417                 kobj->state_add_uevent_sent = 1;
 418         else if (action == KOBJ_REMOVE)
 419                 kobj->state_remove_uevent_sent = 1;
 420
 421         mutex_lock(&uevent_sock_mutex);
 422         /* we will send an event, so request a new sequence number */
 423         retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum);
 424         if (retval) {
 425                 mutex_unlock(&uevent_sock_mutex);
 426                 goto exit;
 427         }
 428
 429 #if defined(CONFIG_NET)
 430         /* send netlink message */
 431         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 432                 struct sock *uevent_sock = ue_sk->sk;
 433                 struct sk_buff *skb;
 434                 size_t len;
 435
 436                 if (!netlink_has_listeners(uevent_sock, 1))
 437                         continue;
 438
 439                 /* allocate message with the maximum possible size */
 440                 len = strlen(action_string) + strlen(devpath) + 2;
 441                 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
 442                 if (skb) {
 443                         char *scratch;
 444
 445                         /* add header */
 446                         scratch = skb_put(skb, len);
 447                         sprintf(scratch, "%s@%s", action_string, devpath);
 448
 449                         /* copy keys to our continuous event payload buffer */
 450                         for (i = 0; i < env->envp_idx; i++) {
 451                                 len = strlen(env->envp[i]) + 1;
 452                                 scratch = skb_put(skb, len);
 453                                 strcpy(scratch, env->envp[i]);
 454                         }
 455
 456                         NETLINK_CB(skb).dst_group = 1;
 457                         retval = netlink_broadcast_filtered(uevent_sock, skb,
 458                                                             0, 1, GFP_KERNEL,
 459                                                             kobj_bcast_filter,
 460                                                             kobj);
 461                         /* ENOBUFS should be handled in userspace */
 462                         if (retval == -ENOBUFS || retval == -ESRCH)
 463                                 retval = 0;
 464                 } else
 465                         retval = -ENOMEM;
 466         }
 467 #endif
 468         mutex_unlock(&uevent_sock_mutex);
 469
 470 #ifdef CONFIG_UEVENT_HELPER
 471         /* call uevent_helper, usually only enabled during early boot */
 472         if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
 473                 struct subprocess_info *info;
 474
 475                 retval = add_uevent_var(env, "HOME=/");
 476                 if (retval)
 477                         goto exit;
 478                 retval = add_uevent_var(env,
 479                                         "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
 480                 if (retval)
 481                         goto exit;
 482                 retval = init_uevent_argv(env, subsystem);
 483                 if (retval)
 484                         goto exit;
 485
 486                 retval = -ENOMEM;
 487                 info = call_usermodehelper_setup(env->argv[0], env->argv,
 488                                                  env->envp, GFP_KERNEL,
 489                                                  NULL, cleanup_uevent_env, env);
 490                 if (info) {
 491                         retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
 492                         env = NULL;     /* freed by cleanup_uevent_env */
 493                 }
 494         }
 495 #endif
 496
 497 exit:
 498         kfree(devpath);
 499         kfree(env);
 500         return retval;
 501 }
 502 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 503
 504 /**
 505  * kobject_uevent - notify userspace by sending an uevent
 506  *
 507  * @kobj: struct kobject that the action is happening to
 508  * @action: action that is happening
 509  *
 510  * Returns 0 if kobject_uevent() is completed with success or the
 511  * corresponding error when it fails.
 512  */
 513 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 514 {
 515         return kobject_uevent_env(kobj, action, NULL);
 516 }
 517 EXPORT_SYMBOL_GPL(kobject_uevent);
 518
 519 /**
 520  * add_uevent_var - add key value string to the environment buffer
 521  * @env: environment buffer structure
 522  * @format: printf format for the key=value pair
 523  *
 524  * Returns 0 if environment variable was added successfully or -ENOMEM
 525  * if no space was available.
 526  */
 527 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 528 {
 529         va_list args;
 530         int len;
 531
 532         if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
 533                 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
 534                 return -ENOMEM;
 535         }
 536
 537         va_start(args, format);
 538         len = vsnprintf(&env->buf[env->buflen],
 539                         sizeof(env->buf) - env->buflen,
 540                         format, args);
 541         va_end(args);
 542
 543         if (len >= (sizeof(env->buf) - env->buflen)) {
 544                 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
 545                 return -ENOMEM;
 546         }
 547
 548         env->envp[env->envp_idx++] = &env->buf[env->buflen];
 549         env->buflen += len + 1;
 550         return 0;
 551 }
 552 EXPORT_SYMBOL_GPL(add_uevent_var);
 553
 554 #if defined(CONFIG_NET)
 555 static int uevent_net_init(struct net *net)
 556 {
 557         struct uevent_sock *ue_sk;
 558         struct netlink_kernel_cfg cfg = {
 559                 .groups = 1,
 560                 .flags  = NL_CFG_F_NONROOT_RECV,
 561         };
 562
 563         ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
 564         if (!ue_sk)
 565                 return -ENOMEM;
 566
 567         ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
 568         if (!ue_sk->sk) {
 569                 printk(KERN_ERR
 570                        "kobject_uevent: unable to create netlink socket!\n");
 571                 kfree(ue_sk);
 572                 return -ENODEV;
 573         }
 574         mutex_lock(&uevent_sock_mutex);
 575         list_add_tail(&ue_sk->list, &uevent_sock_list);
 576         mutex_unlock(&uevent_sock_mutex);
 577         return 0;
 578 }
 579
 580 static void uevent_net_exit(struct net *net)
 581 {
 582         struct uevent_sock *ue_sk;
 583
 584         mutex_lock(&uevent_sock_mutex);
 585         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 586                 if (sock_net(ue_sk->sk) == net)
 587                         goto found;
 588         }
 589         mutex_unlock(&uevent_sock_mutex);
 590         return;
 591
 592 found:
 593         list_del(&ue_sk->list);
 594         mutex_unlock(&uevent_sock_mutex);
 595
 596         netlink_kernel_release(ue_sk->sk);
 597         kfree(ue_sk);
 598 }
 599
 600 static struct pernet_operations uevent_net_ops = {
 601         .init   = uevent_net_init,
 602         .exit   = uevent_net_exit,
 603 };
 604
 605 static int __init kobject_uevent_init(void)
 606 {
 607         return register_pernet_subsys(&uevent_net_ops);
 608 }
 609
 610
 611 postcore_initcall(kobject_uevent_init);
 612 #endif