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         [KOBJ_BIND] =           "bind",
  56         [KOBJ_UNBIND] =         "unbind",
  57 };
  58
  59 static int kobject_action_type(const char *buf, size_t count,
  60                                enum kobject_action *type,
  61                                const char **args)
  62 {
  63         enum kobject_action action;
  64         size_t count_first;
  65         const char *args_start;
  66         int ret = -EINVAL;
  67
  68         if (count && (buf[count-1] == '\n' || buf[count-1] == '\0'))
  69                 count--;
  70
  71         if (!count)
  72                 goto out;
  73
  74         args_start = strnchr(buf, count, ' ');
  75         if (args_start) {
  76                 count_first = args_start - buf;
  77                 args_start = args_start + 1;
  78         } else
  79                 count_first = count;
  80
  81         for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
  82                 if (strncmp(kobject_actions[action], buf, count_first) != 0)
  83                         continue;
  84                 if (kobject_actions[action][count_first] != '\0')
  85                         continue;
  86                 if (args)
  87                         *args = args_start;
  88                 *type = action;
  89                 ret = 0;
  90                 break;
  91         }
  92 out:
  93         return ret;
  94 }
  95
  96 static const char *action_arg_word_end(const char *buf, const char *buf_end,
  97                                        char delim)
  98 {
  99         const char *next = buf;
 100
 101         while (next <= buf_end && *next != delim)
 102                 if (!isalnum(*next++))
 103                         return NULL;
 104
 105         if (next == buf)
 106                 return NULL;
 107
 108         return next;
 109 }
 110
 111 static int kobject_action_args(const char *buf, size_t count,
 112                                struct kobj_uevent_env **ret_env)
 113 {
 114         struct kobj_uevent_env *env = NULL;
 115         const char *next, *buf_end, *key;
 116         int key_len;
 117         int r = -EINVAL;
 118
 119         if (count && (buf[count - 1] == '\n' || buf[count - 1] == '\0'))
 120                 count--;
 121
 122         if (!count)
 123                 return -EINVAL;
 124
 125         env = kzalloc(sizeof(*env), GFP_KERNEL);
 126         if (!env)
 127                 return -ENOMEM;
 128
 129         /* first arg is UUID */
 130         if (count < UUID_STRING_LEN || !uuid_is_valid(buf) ||
 131             add_uevent_var(env, "SYNTH_UUID=%.*s", UUID_STRING_LEN, buf))
 132                 goto out;
 133
 134         /*
 135          * the rest are custom environment variables in KEY=VALUE
 136          * format with ' ' delimiter between each KEY=VALUE pair
 137          */
 138         next = buf + UUID_STRING_LEN;
 139         buf_end = buf + count - 1;
 140
 141         while (next <= buf_end) {
 142                 if (*next != ' ')
 143                         goto out;
 144
 145                 /* skip the ' ', key must follow */
 146                 key = ++next;
 147                 if (key > buf_end)
 148                         goto out;
 149
 150                 buf = next;
 151                 next = action_arg_word_end(buf, buf_end, '=');
 152                 if (!next || next > buf_end || *next != '=')
 153                         goto out;
 154                 key_len = next - buf;
 155
 156                 /* skip the '=', value must follow */
 157                 if (++next > buf_end)
 158                         goto out;
 159
 160                 buf = next;
 161                 next = action_arg_word_end(buf, buf_end, ' ');
 162                 if (!next)
 163                         goto out;
 164
 165                 if (add_uevent_var(env, "SYNTH_ARG_%.*s=%.*s",
 166                                    key_len, key, (int) (next - buf), buf))
 167                         goto out;
 168         }
 169
 170         r = 0;
 171 out:
 172         if (r)
 173                 kfree(env);
 174         else
 175                 *ret_env = env;
 176         return r;
 177 }
 178
 179 /**
 180  * kobject_synth_uevent - send synthetic uevent with arguments
 181  *
 182  * @kobj: struct kobject for which synthetic uevent is to be generated
 183  * @buf: buffer containing action type and action args, newline is ignored
 184  * @count: length of buffer
 185  *
 186  * Returns 0 if kobject_synthetic_uevent() is completed with success or the
 187  * corresponding error when it fails.
 188  */
 189 int kobject_synth_uevent(struct kobject *kobj, const char *buf, size_t count)
 190 {
 191         char *no_uuid_envp[] = { "SYNTH_UUID=0", NULL };
 192         enum kobject_action action;
 193         const char *action_args;
 194         struct kobj_uevent_env *env;
 195         const char *msg = NULL, *devpath;
 196         int r;
 197
 198         r = kobject_action_type(buf, count, &action, &action_args);
 199         if (r) {
 200                 msg = "unknown uevent action string\n";
 201                 goto out;
 202         }
 203
 204         if (!action_args) {
 205                 r = kobject_uevent_env(kobj, action, no_uuid_envp);
 206                 goto out;
 207         }
 208
 209         r = kobject_action_args(action_args,
 210                                 count - (action_args - buf), &env);
 211         if (r == -EINVAL) {
 212                 msg = "incorrect uevent action arguments\n";
 213                 goto out;
 214         }
 215
 216         if (r)
 217                 goto out;
 218
 219         r = kobject_uevent_env(kobj, action, env->envp);
 220         kfree(env);
 221 out:
 222         if (r) {
 223                 devpath = kobject_get_path(kobj, GFP_KERNEL);
 224                 printk(KERN_WARNING "synth uevent: %s: %s",
 225                        devpath ?: "unknown device",
 226                        msg ?: "failed to send uevent");
 227                 kfree(devpath);
 228         }
 229         return r;
 230 }
 231
 232 #ifdef CONFIG_NET
 233 static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data)
 234 {
 235         struct kobject *kobj = data, *ksobj;
 236         const struct kobj_ns_type_operations *ops;
 237
 238         ops = kobj_ns_ops(kobj);
 239         if (!ops && kobj->kset) {
 240                 ksobj = &kobj->kset->kobj;
 241                 if (ksobj->parent != NULL)
 242                         ops = kobj_ns_ops(ksobj->parent);
 243         }
 244
 245         if (ops && ops->netlink_ns && kobj->ktype->namespace) {
 246                 const void *sock_ns, *ns;
 247                 ns = kobj->ktype->namespace(kobj);
 248                 sock_ns = ops->netlink_ns(dsk);
 249                 return sock_ns != ns;
 250         }
 251
 252         return 0;
 253 }
 254 #endif
 255
 256 #ifdef CONFIG_UEVENT_HELPER
 257 static int kobj_usermode_filter(struct kobject *kobj)
 258 {
 259         const struct kobj_ns_type_operations *ops;
 260
 261         ops = kobj_ns_ops(kobj);
 262         if (ops) {
 263                 const void *init_ns, *ns;
 264                 ns = kobj->ktype->namespace(kobj);
 265                 init_ns = ops->initial_ns();
 266                 return ns != init_ns;
 267         }
 268
 269         return 0;
 270 }
 271
 272 static int init_uevent_argv(struct kobj_uevent_env *env, const char *subsystem)
 273 {
 274         int len;
 275
 276         len = strlcpy(&env->buf[env->buflen], subsystem,
 277                       sizeof(env->buf) - env->buflen);
 278         if (len >= (sizeof(env->buf) - env->buflen)) {
 279                 WARN(1, KERN_ERR "init_uevent_argv: buffer size too small\n");
 280                 return -ENOMEM;
 281         }
 282
 283         env->argv[0] = uevent_helper;
 284         env->argv[1] = &env->buf[env->buflen];
 285         env->argv[2] = NULL;
 286
 287         env->buflen += len + 1;
 288         return 0;
 289 }
 290
 291 static void cleanup_uevent_env(struct subprocess_info *info)
 292 {
 293         kfree(info->data);
 294 }
 295 #endif
 296
 297 static int kobject_uevent_net_broadcast(struct kobject *kobj,
 298                                         struct kobj_uevent_env *env,
 299                                         const char *action_string,
 300                                         const char *devpath)
 301 {
 302         int retval = 0;
 303 #if defined(CONFIG_NET)
 304         struct sk_buff *skb = NULL;
 305         struct uevent_sock *ue_sk;
 306
 307         /* send netlink message */
 308         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 309                 struct sock *uevent_sock = ue_sk->sk;
 310
 311                 if (!netlink_has_listeners(uevent_sock, 1))
 312                         continue;
 313
 314                 if (!skb) {
 315                         /* allocate message with the maximum possible size */
 316                         size_t len = strlen(action_string) + strlen(devpath) + 2;
 317                         char *scratch;
 318
 319                         retval = -ENOMEM;
 320                         skb = alloc_skb(len + env->buflen, GFP_KERNEL);
 321                         if (!skb)
 322                                 continue;
 323
 324                         /* add header */
 325                         scratch = skb_put(skb, len);
 326                         sprintf(scratch, "%s@%s", action_string, devpath);
 327
 328                         skb_put_data(skb, env->buf, env->buflen);
 329
 330                         NETLINK_CB(skb).dst_group = 1;
 331                 }
 332
 333                 retval = netlink_broadcast_filtered(uevent_sock, skb_get(skb),
 334                                                     0, 1, GFP_KERNEL,
 335                                                     kobj_bcast_filter,
 336                                                     kobj);
 337                 /* ENOBUFS should be handled in userspace */
 338                 if (retval == -ENOBUFS || retval == -ESRCH)
 339                         retval = 0;
 340         }
 341         consume_skb(skb);
 342 #endif
 343         return retval;
 344 }
 345
 346 static void zap_modalias_env(struct kobj_uevent_env *env)
 347 {
 348         static const char modalias_prefix[] = "MODALIAS=";
 349         int i;
 350
 351         for (i = 0; i < env->envp_idx;) {
 352                 if (strncmp(env->envp[i], modalias_prefix,
 353                             sizeof(modalias_prefix) - 1)) {
 354                         i++;
 355                         continue;
 356                 }
 357
 358                 if (i != env->envp_idx - 1)
 359                         memmove(&env->envp[i], &env->envp[i + 1],
 360                                 sizeof(env->envp[i]) * env->envp_idx - 1);
 361
 362                 env->envp_idx--;
 363         }
 364 }
 365
 366 /**
 367  * kobject_uevent_env - send an uevent with environmental data
 368  *
 369  * @kobj: struct kobject that the action is happening to
 370  * @action: action that is happening
 371  * @envp_ext: pointer to environmental data
 372  *
 373  * Returns 0 if kobject_uevent_env() is completed with success or the
 374  * corresponding error when it fails.
 375  */
 376 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
 377                        char *envp_ext[])
 378 {
 379         struct kobj_uevent_env *env;
 380         const char *action_string = kobject_actions[action];
 381         const char *devpath = NULL;
 382         const char *subsystem;
 383         struct kobject *top_kobj;
 384         struct kset *kset;
 385         const struct kset_uevent_ops *uevent_ops;
 386         int i = 0;
 387         int retval = 0;
 388
 389         pr_debug("kobject: '%s' (%p): %s\n",
 390                  kobject_name(kobj), kobj, __func__);
 391
 392         /* search the kset we belong to */
 393         top_kobj = kobj;
 394         while (!top_kobj->kset && top_kobj->parent)
 395                 top_kobj = top_kobj->parent;
 396
 397         if (!top_kobj->kset) {
 398                 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
 399                          "without kset!\n", kobject_name(kobj), kobj,
 400                          __func__);
 401                 return -EINVAL;
 402         }
 403
 404         kset = top_kobj->kset;
 405         uevent_ops = kset->uevent_ops;
 406
 407         /* skip the event, if uevent_suppress is set*/
 408         if (kobj->uevent_suppress) {
 409                 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
 410                                  "caused the event to drop!\n",
 411                                  kobject_name(kobj), kobj, __func__);
 412                 return 0;
 413         }
 414         /* skip the event, if the filter returns zero. */
 415         if (uevent_ops && uevent_ops->filter)
 416                 if (!uevent_ops->filter(kset, kobj)) {
 417                         pr_debug("kobject: '%s' (%p): %s: filter function "
 418                                  "caused the event to drop!\n",
 419                                  kobject_name(kobj), kobj, __func__);
 420                         return 0;
 421                 }
 422
 423         /* originating subsystem */
 424         if (uevent_ops && uevent_ops->name)
 425                 subsystem = uevent_ops->name(kset, kobj);
 426         else
 427                 subsystem = kobject_name(&kset->kobj);
 428         if (!subsystem) {
 429                 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
 430                          "event to drop!\n", kobject_name(kobj), kobj,
 431                          __func__);
 432                 return 0;
 433         }
 434
 435         /* environment buffer */
 436         env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
 437         if (!env)
 438                 return -ENOMEM;
 439
 440         /* complete object path */
 441         devpath = kobject_get_path(kobj, GFP_KERNEL);
 442         if (!devpath) {
 443                 retval = -ENOENT;
 444                 goto exit;
 445         }
 446
 447         /* default keys */
 448         retval = add_uevent_var(env, "ACTION=%s", action_string);
 449         if (retval)
 450                 goto exit;
 451         retval = add_uevent_var(env, "DEVPATH=%s", devpath);
 452         if (retval)
 453                 goto exit;
 454         retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
 455         if (retval)
 456                 goto exit;
 457
 458         /* keys passed in from the caller */
 459         if (envp_ext) {
 460                 for (i = 0; envp_ext[i]; i++) {
 461                         retval = add_uevent_var(env, "%s", envp_ext[i]);
 462                         if (retval)
 463                                 goto exit;
 464                 }
 465         }
 466
 467         /* let the kset specific function add its stuff */
 468         if (uevent_ops && uevent_ops->uevent) {
 469                 retval = uevent_ops->uevent(kset, kobj, env);
 470                 if (retval) {
 471                         pr_debug("kobject: '%s' (%p): %s: uevent() returned "
 472                                  "%d\n", kobject_name(kobj), kobj,
 473                                  __func__, retval);
 474                         goto exit;
 475                 }
 476         }
 477
 478         switch (action) {
 479         case KOBJ_ADD:
 480                 /*
 481                  * Mark "add" event so we can make sure we deliver "remove"
 482                  * event to userspace during automatic cleanup. If
 483                  * the object did send an "add" event, "remove" will
 484                  * automatically generated by the core, if not already done
 485                  * by the caller.
 486                  */
 487                 kobj->state_add_uevent_sent = 1;
 488                 break;
 489
 490         case KOBJ_REMOVE:
 491                 kobj->state_remove_uevent_sent = 1;
 492                 break;
 493
 494         case KOBJ_UNBIND:
 495                 zap_modalias_env(env);
 496                 break;
 497
 498         default:
 499                 break;
 500         }
 501
 502         mutex_lock(&uevent_sock_mutex);
 503         /* we will send an event, so request a new sequence number */
 504         retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum);
 505         if (retval) {
 506                 mutex_unlock(&uevent_sock_mutex);
 507                 goto exit;
 508         }
 509         retval = kobject_uevent_net_broadcast(kobj, env, action_string,
 510                                               devpath);
 511         mutex_unlock(&uevent_sock_mutex);
 512
 513 #ifdef CONFIG_UEVENT_HELPER
 514         /* call uevent_helper, usually only enabled during early boot */
 515         if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
 516                 struct subprocess_info *info;
 517
 518                 retval = add_uevent_var(env, "HOME=/");
 519                 if (retval)
 520                         goto exit;
 521                 retval = add_uevent_var(env,
 522                                         "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
 523                 if (retval)
 524                         goto exit;
 525                 retval = init_uevent_argv(env, subsystem);
 526                 if (retval)
 527                         goto exit;
 528
 529                 retval = -ENOMEM;
 530                 info = call_usermodehelper_setup(env->argv[0], env->argv,
 531                                                  env->envp, GFP_KERNEL,
 532                                                  NULL, cleanup_uevent_env, env);
 533                 if (info) {
 534                         retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
 535                         env = NULL;     /* freed by cleanup_uevent_env */
 536                 }
 537         }
 538 #endif
 539
 540 exit:
 541         kfree(devpath);
 542         kfree(env);
 543         return retval;
 544 }
 545 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 546
 547 /**
 548  * kobject_uevent - notify userspace by sending an uevent
 549  *
 550  * @kobj: struct kobject that the action is happening to
 551  * @action: action that is happening
 552  *
 553  * Returns 0 if kobject_uevent() is completed with success or the
 554  * corresponding error when it fails.
 555  */
 556 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 557 {
 558         return kobject_uevent_env(kobj, action, NULL);
 559 }
 560 EXPORT_SYMBOL_GPL(kobject_uevent);
 561
 562 /**
 563  * add_uevent_var - add key value string to the environment buffer
 564  * @env: environment buffer structure
 565  * @format: printf format for the key=value pair
 566  *
 567  * Returns 0 if environment variable was added successfully or -ENOMEM
 568  * if no space was available.
 569  */
 570 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 571 {
 572         va_list args;
 573         int len;
 574
 575         if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
 576                 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
 577                 return -ENOMEM;
 578         }
 579
 580         va_start(args, format);
 581         len = vsnprintf(&env->buf[env->buflen],
 582                         sizeof(env->buf) - env->buflen,
 583                         format, args);
 584         va_end(args);
 585
 586         if (len >= (sizeof(env->buf) - env->buflen)) {
 587                 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
 588                 return -ENOMEM;
 589         }
 590
 591         env->envp[env->envp_idx++] = &env->buf[env->buflen];
 592         env->buflen += len + 1;
 593         return 0;
 594 }
 595 EXPORT_SYMBOL_GPL(add_uevent_var);
 596
 597 #if defined(CONFIG_NET)
 598 static int uevent_net_init(struct net *net)
 599 {
 600         struct uevent_sock *ue_sk;
 601         struct netlink_kernel_cfg cfg = {
 602                 .groups = 1,
 603                 .flags  = NL_CFG_F_NONROOT_RECV,
 604         };
 605
 606         ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
 607         if (!ue_sk)
 608                 return -ENOMEM;
 609
 610         ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
 611         if (!ue_sk->sk) {
 612                 printk(KERN_ERR
 613                        "kobject_uevent: unable to create netlink socket!\n");
 614                 kfree(ue_sk);
 615                 return -ENODEV;
 616         }
 617         mutex_lock(&uevent_sock_mutex);
 618         list_add_tail(&ue_sk->list, &uevent_sock_list);
 619         mutex_unlock(&uevent_sock_mutex);
 620         return 0;
 621 }
 622
 623 static void uevent_net_exit(struct net *net)
 624 {
 625         struct uevent_sock *ue_sk;
 626
 627         mutex_lock(&uevent_sock_mutex);
 628         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 629                 if (sock_net(ue_sk->sk) == net)
 630                         goto found;
 631         }
 632         mutex_unlock(&uevent_sock_mutex);
 633         return;
 634
 635 found:
 636         list_del(&ue_sk->list);
 637         mutex_unlock(&uevent_sock_mutex);
 638
 639         netlink_kernel_release(ue_sk->sk);
 640         kfree(ue_sk);
 641 }
 642
 643 static struct pernet_operations uevent_net_ops = {
 644         .init   = uevent_net_init,
 645         .exit   = uevent_net_exit,
 646 };
 647
 648 static int __init kobject_uevent_init(void)
 649 {
 650         return register_pernet_subsys(&uevent_net_ops);
 651 }
 652
 653
 654 postcore_initcall(kobject_uevent_init);
 655 #endif