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         size_t len;
 350         int i, j;
 351
 352         for (i = 0; i < env->envp_idx;) {
 353                 if (strncmp(env->envp[i], modalias_prefix,
 354                             sizeof(modalias_prefix) - 1)) {
 355                         i++;
 356                         continue;
 357                 }
 358
 359                 len = strlen(env->envp[i]) + 1;
 360
 361                 if (i != env->envp_idx - 1) {
 362                         memmove(env->envp[i], env->envp[i + 1],
 363                                 env->buflen - len);
 364
 365                         for (j = i; j < env->envp_idx - 1; j++)
 366                                 env->envp[j] = env->envp[j + 1] - len;
 367                 }
 368
 369                 env->envp_idx--;
 370                 env->buflen -= len;
 371         }
 372 }
 373
 374 /**
 375  * kobject_uevent_env - send an uevent with environmental data
 376  *
 377  * @kobj: struct kobject that the action is happening to
 378  * @action: action that is happening
 379  * @envp_ext: pointer to environmental data
 380  *
 381  * Returns 0 if kobject_uevent_env() is completed with success or the
 382  * corresponding error when it fails.
 383  */
 384 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
 385                        char *envp_ext[])
 386 {
 387         struct kobj_uevent_env *env;
 388         const char *action_string = kobject_actions[action];
 389         const char *devpath = NULL;
 390         const char *subsystem;
 391         struct kobject *top_kobj;
 392         struct kset *kset;
 393         const struct kset_uevent_ops *uevent_ops;
 394         int i = 0;
 395         int retval = 0;
 396
 397         /*
 398          * Mark "remove" event done regardless of result, for some subsystems
 399          * do not want to re-trigger "remove" event via automatic cleanup.
 400          */
 401         if (action == KOBJ_REMOVE)
 402                 kobj->state_remove_uevent_sent = 1;
 403
 404         pr_debug("kobject: '%s' (%p): %s\n",
 405                  kobject_name(kobj), kobj, __func__);
 406
 407         /* search the kset we belong to */
 408         top_kobj = kobj;
 409         while (!top_kobj->kset && top_kobj->parent)
 410                 top_kobj = top_kobj->parent;
 411
 412         if (!top_kobj->kset) {
 413                 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
 414                          "without kset!\n", kobject_name(kobj), kobj,
 415                          __func__);
 416                 return -EINVAL;
 417         }
 418
 419         kset = top_kobj->kset;
 420         uevent_ops = kset->uevent_ops;
 421
 422         /* skip the event, if uevent_suppress is set*/
 423         if (kobj->uevent_suppress) {
 424                 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
 425                                  "caused the event to drop!\n",
 426                                  kobject_name(kobj), kobj, __func__);
 427                 return 0;
 428         }
 429         /* skip the event, if the filter returns zero. */
 430         if (uevent_ops && uevent_ops->filter)
 431                 if (!uevent_ops->filter(kset, kobj)) {
 432                         pr_debug("kobject: '%s' (%p): %s: filter function "
 433                                  "caused the event to drop!\n",
 434                                  kobject_name(kobj), kobj, __func__);
 435                         return 0;
 436                 }
 437
 438         /* originating subsystem */
 439         if (uevent_ops && uevent_ops->name)
 440                 subsystem = uevent_ops->name(kset, kobj);
 441         else
 442                 subsystem = kobject_name(&kset->kobj);
 443         if (!subsystem) {
 444                 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
 445                          "event to drop!\n", kobject_name(kobj), kobj,
 446                          __func__);
 447                 return 0;
 448         }
 449
 450         /* environment buffer */
 451         env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
 452         if (!env)
 453                 return -ENOMEM;
 454
 455         /* complete object path */
 456         devpath = kobject_get_path(kobj, GFP_KERNEL);
 457         if (!devpath) {
 458                 retval = -ENOENT;
 459                 goto exit;
 460         }
 461
 462         /* default keys */
 463         retval = add_uevent_var(env, "ACTION=%s", action_string);
 464         if (retval)
 465                 goto exit;
 466         retval = add_uevent_var(env, "DEVPATH=%s", devpath);
 467         if (retval)
 468                 goto exit;
 469         retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
 470         if (retval)
 471                 goto exit;
 472
 473         /* keys passed in from the caller */
 474         if (envp_ext) {
 475                 for (i = 0; envp_ext[i]; i++) {
 476                         retval = add_uevent_var(env, "%s", envp_ext[i]);
 477                         if (retval)
 478                                 goto exit;
 479                 }
 480         }
 481
 482         /* let the kset specific function add its stuff */
 483         if (uevent_ops && uevent_ops->uevent) {
 484                 retval = uevent_ops->uevent(kset, kobj, env);
 485                 if (retval) {
 486                         pr_debug("kobject: '%s' (%p): %s: uevent() returned "
 487                                  "%d\n", kobject_name(kobj), kobj,
 488                                  __func__, retval);
 489                         goto exit;
 490                 }
 491         }
 492
 493         switch (action) {
 494         case KOBJ_ADD:
 495                 /*
 496                  * Mark "add" event so we can make sure we deliver "remove"
 497                  * event to userspace during automatic cleanup. If
 498                  * the object did send an "add" event, "remove" will
 499                  * automatically generated by the core, if not already done
 500                  * by the caller.
 501                  */
 502                 kobj->state_add_uevent_sent = 1;
 503                 break;
 504
 505         case KOBJ_UNBIND:
 506                 zap_modalias_env(env);
 507                 break;
 508
 509         default:
 510                 break;
 511         }
 512
 513         mutex_lock(&uevent_sock_mutex);
 514         /* we will send an event, so request a new sequence number */
 515         retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum);
 516         if (retval) {
 517                 mutex_unlock(&uevent_sock_mutex);
 518                 goto exit;
 519         }
 520         retval = kobject_uevent_net_broadcast(kobj, env, action_string,
 521                                               devpath);
 522         mutex_unlock(&uevent_sock_mutex);
 523
 524 #ifdef CONFIG_UEVENT_HELPER
 525         /* call uevent_helper, usually only enabled during early boot */
 526         if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
 527                 struct subprocess_info *info;
 528
 529                 retval = add_uevent_var(env, "HOME=/");
 530                 if (retval)
 531                         goto exit;
 532                 retval = add_uevent_var(env,
 533                                         "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
 534                 if (retval)
 535                         goto exit;
 536                 retval = init_uevent_argv(env, subsystem);
 537                 if (retval)
 538                         goto exit;
 539
 540                 retval = -ENOMEM;
 541                 info = call_usermodehelper_setup(env->argv[0], env->argv,
 542                                                  env->envp, GFP_KERNEL,
 543                                                  NULL, cleanup_uevent_env, env);
 544                 if (info) {
 545                         retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
 546                         env = NULL;     /* freed by cleanup_uevent_env */
 547                 }
 548         }
 549 #endif
 550
 551 exit:
 552         kfree(devpath);
 553         kfree(env);
 554         return retval;
 555 }
 556 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 557
 558 /**
 559  * kobject_uevent - notify userspace by sending an uevent
 560  *
 561  * @kobj: struct kobject that the action is happening to
 562  * @action: action that is happening
 563  *
 564  * Returns 0 if kobject_uevent() is completed with success or the
 565  * corresponding error when it fails.
 566  */
 567 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 568 {
 569         return kobject_uevent_env(kobj, action, NULL);
 570 }
 571 EXPORT_SYMBOL_GPL(kobject_uevent);
 572
 573 /**
 574  * add_uevent_var - add key value string to the environment buffer
 575  * @env: environment buffer structure
 576  * @format: printf format for the key=value pair
 577  *
 578  * Returns 0 if environment variable was added successfully or -ENOMEM
 579  * if no space was available.
 580  */
 581 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 582 {
 583         va_list args;
 584         int len;
 585
 586         if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
 587                 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
 588                 return -ENOMEM;
 589         }
 590
 591         va_start(args, format);
 592         len = vsnprintf(&env->buf[env->buflen],
 593                         sizeof(env->buf) - env->buflen,
 594                         format, args);
 595         va_end(args);
 596
 597         if (len >= (sizeof(env->buf) - env->buflen)) {
 598                 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
 599                 return -ENOMEM;
 600         }
 601
 602         env->envp[env->envp_idx++] = &env->buf[env->buflen];
 603         env->buflen += len + 1;
 604         return 0;
 605 }
 606 EXPORT_SYMBOL_GPL(add_uevent_var);
 607
 608 #if defined(CONFIG_NET)
 609 static int uevent_net_init(struct net *net)
 610 {
 611         struct uevent_sock *ue_sk;
 612         struct netlink_kernel_cfg cfg = {
 613                 .groups = 1,
 614                 .flags  = NL_CFG_F_NONROOT_RECV,
 615         };
 616
 617         ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
 618         if (!ue_sk)
 619                 return -ENOMEM;
 620
 621         ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
 622         if (!ue_sk->sk) {
 623                 printk(KERN_ERR
 624                        "kobject_uevent: unable to create netlink socket!\n");
 625                 kfree(ue_sk);
 626                 return -ENODEV;
 627         }
 628         mutex_lock(&uevent_sock_mutex);
 629         list_add_tail(&ue_sk->list, &uevent_sock_list);
 630         mutex_unlock(&uevent_sock_mutex);
 631         return 0;
 632 }
 633
 634 static void uevent_net_exit(struct net *net)
 635 {
 636         struct uevent_sock *ue_sk;
 637
 638         mutex_lock(&uevent_sock_mutex);
 639         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 640                 if (sock_net(ue_sk->sk) == net)
 641                         goto found;
 642         }
 643         mutex_unlock(&uevent_sock_mutex);
 644         return;
 645
 646 found:
 647         list_del(&ue_sk->list);
 648         mutex_unlock(&uevent_sock_mutex);
 649
 650         netlink_kernel_release(ue_sk->sk);
 651         kfree(ue_sk);
 652 }
 653
 654 static struct pernet_operations uevent_net_ops = {
 655         .init   = uevent_net_init,
 656         .exit   = uevent_net_exit,
 657 };
 658
 659 static int __init kobject_uevent_init(void)
 660 {
 661         return register_pernet_subsys(&uevent_net_ops);
 662 }
 663
 664
 665 postcore_initcall(kobject_uevent_init);
 666 #endif