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 void zap_modalias_env(struct kobj_uevent_env *env)
 298 {
 299         static const char modalias_prefix[] = "MODALIAS=";
 300         int i;
 301
 302         for (i = 0; i < env->envp_idx;) {
 303                 if (strncmp(env->envp[i], modalias_prefix,
 304                             sizeof(modalias_prefix) - 1)) {
 305                         i++;
 306                         continue;
 307                 }
 308
 309                 if (i != env->envp_idx - 1)
 310                         memmove(&env->envp[i], &env->envp[i + 1],
 311                                 sizeof(env->envp[i]) * env->envp_idx - 1);
 312
 313                 env->envp_idx--;
 314         }
 315 }
 316
 317 /**
 318  * kobject_uevent_env - send an uevent with environmental data
 319  *
 320  * @kobj: struct kobject that the action is happening to
 321  * @action: action that is happening
 322  * @envp_ext: pointer to environmental data
 323  *
 324  * Returns 0 if kobject_uevent_env() is completed with success or the
 325  * corresponding error when it fails.
 326  */
 327 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
 328                        char *envp_ext[])
 329 {
 330         struct kobj_uevent_env *env;
 331         const char *action_string = kobject_actions[action];
 332         const char *devpath = NULL;
 333         const char *subsystem;
 334         struct kobject *top_kobj;
 335         struct kset *kset;
 336         const struct kset_uevent_ops *uevent_ops;
 337         int i = 0;
 338         int retval = 0;
 339 #ifdef CONFIG_NET
 340         struct uevent_sock *ue_sk;
 341 #endif
 342
 343         /*
 344          * Mark "remove" event done regardless of result, for some subsystems
 345          * do not want to re-trigger "remove" event via automatic cleanup.
 346          */
 347         if (action == KOBJ_REMOVE)
 348                 kobj->state_remove_uevent_sent = 1;
 349
 350         pr_debug("kobject: '%s' (%p): %s\n",
 351                  kobject_name(kobj), kobj, __func__);
 352
 353         /* search the kset we belong to */
 354         top_kobj = kobj;
 355         while (!top_kobj->kset && top_kobj->parent)
 356                 top_kobj = top_kobj->parent;
 357
 358         if (!top_kobj->kset) {
 359                 pr_debug("kobject: '%s' (%p): %s: attempted to send uevent "
 360                          "without kset!\n", kobject_name(kobj), kobj,
 361                          __func__);
 362                 return -EINVAL;
 363         }
 364
 365         kset = top_kobj->kset;
 366         uevent_ops = kset->uevent_ops;
 367
 368         /* skip the event, if uevent_suppress is set*/
 369         if (kobj->uevent_suppress) {
 370                 pr_debug("kobject: '%s' (%p): %s: uevent_suppress "
 371                                  "caused the event to drop!\n",
 372                                  kobject_name(kobj), kobj, __func__);
 373                 return 0;
 374         }
 375         /* skip the event, if the filter returns zero. */
 376         if (uevent_ops && uevent_ops->filter)
 377                 if (!uevent_ops->filter(kset, kobj)) {
 378                         pr_debug("kobject: '%s' (%p): %s: filter function "
 379                                  "caused the event to drop!\n",
 380                                  kobject_name(kobj), kobj, __func__);
 381                         return 0;
 382                 }
 383
 384         /* originating subsystem */
 385         if (uevent_ops && uevent_ops->name)
 386                 subsystem = uevent_ops->name(kset, kobj);
 387         else
 388                 subsystem = kobject_name(&kset->kobj);
 389         if (!subsystem) {
 390                 pr_debug("kobject: '%s' (%p): %s: unset subsystem caused the "
 391                          "event to drop!\n", kobject_name(kobj), kobj,
 392                          __func__);
 393                 return 0;
 394         }
 395
 396         /* environment buffer */
 397         env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
 398         if (!env)
 399                 return -ENOMEM;
 400
 401         /* complete object path */
 402         devpath = kobject_get_path(kobj, GFP_KERNEL);
 403         if (!devpath) {
 404                 retval = -ENOENT;
 405                 goto exit;
 406         }
 407
 408         /* default keys */
 409         retval = add_uevent_var(env, "ACTION=%s", action_string);
 410         if (retval)
 411                 goto exit;
 412         retval = add_uevent_var(env, "DEVPATH=%s", devpath);
 413         if (retval)
 414                 goto exit;
 415         retval = add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
 416         if (retval)
 417                 goto exit;
 418
 419         /* keys passed in from the caller */
 420         if (envp_ext) {
 421                 for (i = 0; envp_ext[i]; i++) {
 422                         retval = add_uevent_var(env, "%s", envp_ext[i]);
 423                         if (retval)
 424                                 goto exit;
 425                 }
 426         }
 427
 428         /* let the kset specific function add its stuff */
 429         if (uevent_ops && uevent_ops->uevent) {
 430                 retval = uevent_ops->uevent(kset, kobj, env);
 431                 if (retval) {
 432                         pr_debug("kobject: '%s' (%p): %s: uevent() returned "
 433                                  "%d\n", kobject_name(kobj), kobj,
 434                                  __func__, retval);
 435                         goto exit;
 436                 }
 437         }
 438
 439         switch (action) {
 440         case KOBJ_ADD:
 441                 /*
 442                  * Mark "add" event so we can make sure we deliver "remove"
 443                  * event to userspace during automatic cleanup. If
 444                  * the object did send an "add" event, "remove" will
 445                  * automatically generated by the core, if not already done
 446                  * by the caller.
 447                  */
 448                 kobj->state_add_uevent_sent = 1;
 449                 break;
 450
 451         case KOBJ_UNBIND:
 452                 zap_modalias_env(env);
 453                 break;
 454
 455         default:
 456                 break;
 457         }
 458
 459         mutex_lock(&uevent_sock_mutex);
 460         /* we will send an event, so request a new sequence number */
 461         retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum);
 462         if (retval) {
 463                 mutex_unlock(&uevent_sock_mutex);
 464                 goto exit;
 465         }
 466
 467 #if defined(CONFIG_NET)
 468         /* send netlink message */
 469         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 470                 struct sock *uevent_sock = ue_sk->sk;
 471                 struct sk_buff *skb;
 472                 size_t len;
 473
 474                 if (!netlink_has_listeners(uevent_sock, 1))
 475                         continue;
 476
 477                 /* allocate message with the maximum possible size */
 478                 len = strlen(action_string) + strlen(devpath) + 2;
 479                 skb = alloc_skb(len + env->buflen, GFP_KERNEL);
 480                 if (skb) {
 481                         char *scratch;
 482
 483                         /* add header */
 484                         scratch = skb_put(skb, len);
 485                         sprintf(scratch, "%s@%s", action_string, devpath);
 486
 487                         /* copy keys to our continuous event payload buffer */
 488                         for (i = 0; i < env->envp_idx; i++) {
 489                                 len = strlen(env->envp[i]) + 1;
 490                                 scratch = skb_put(skb, len);
 491                                 strcpy(scratch, env->envp[i]);
 492                         }
 493
 494                         NETLINK_CB(skb).dst_group = 1;
 495                         retval = netlink_broadcast_filtered(uevent_sock, skb,
 496                                                             0, 1, GFP_KERNEL,
 497                                                             kobj_bcast_filter,
 498                                                             kobj);
 499                         /* ENOBUFS should be handled in userspace */
 500                         if (retval == -ENOBUFS || retval == -ESRCH)
 501                                 retval = 0;
 502                 } else
 503                         retval = -ENOMEM;
 504         }
 505 #endif
 506         mutex_unlock(&uevent_sock_mutex);
 507
 508 #ifdef CONFIG_UEVENT_HELPER
 509         /* call uevent_helper, usually only enabled during early boot */
 510         if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
 511                 struct subprocess_info *info;
 512
 513                 retval = add_uevent_var(env, "HOME=/");
 514                 if (retval)
 515                         goto exit;
 516                 retval = add_uevent_var(env,
 517                                         "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
 518                 if (retval)
 519                         goto exit;
 520                 retval = init_uevent_argv(env, subsystem);
 521                 if (retval)
 522                         goto exit;
 523
 524                 retval = -ENOMEM;
 525                 info = call_usermodehelper_setup(env->argv[0], env->argv,
 526                                                  env->envp, GFP_KERNEL,
 527                                                  NULL, cleanup_uevent_env, env);
 528                 if (info) {
 529                         retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
 530                         env = NULL;     /* freed by cleanup_uevent_env */
 531                 }
 532         }
 533 #endif
 534
 535 exit:
 536         kfree(devpath);
 537         kfree(env);
 538         return retval;
 539 }
 540 EXPORT_SYMBOL_GPL(kobject_uevent_env);
 541
 542 /**
 543  * kobject_uevent - notify userspace by sending an uevent
 544  *
 545  * @kobj: struct kobject that the action is happening to
 546  * @action: action that is happening
 547  *
 548  * Returns 0 if kobject_uevent() is completed with success or the
 549  * corresponding error when it fails.
 550  */
 551 int kobject_uevent(struct kobject *kobj, enum kobject_action action)
 552 {
 553         return kobject_uevent_env(kobj, action, NULL);
 554 }
 555 EXPORT_SYMBOL_GPL(kobject_uevent);
 556
 557 /**
 558  * add_uevent_var - add key value string to the environment buffer
 559  * @env: environment buffer structure
 560  * @format: printf format for the key=value pair
 561  *
 562  * Returns 0 if environment variable was added successfully or -ENOMEM
 563  * if no space was available.
 564  */
 565 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 566 {
 567         va_list args;
 568         int len;
 569
 570         if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
 571                 WARN(1, KERN_ERR "add_uevent_var: too many keys\n");
 572                 return -ENOMEM;
 573         }
 574
 575         va_start(args, format);
 576         len = vsnprintf(&env->buf[env->buflen],
 577                         sizeof(env->buf) - env->buflen,
 578                         format, args);
 579         va_end(args);
 580
 581         if (len >= (sizeof(env->buf) - env->buflen)) {
 582                 WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n");
 583                 return -ENOMEM;
 584         }
 585
 586         env->envp[env->envp_idx++] = &env->buf[env->buflen];
 587         env->buflen += len + 1;
 588         return 0;
 589 }
 590 EXPORT_SYMBOL_GPL(add_uevent_var);
 591
 592 #if defined(CONFIG_NET)
 593 static int uevent_net_init(struct net *net)
 594 {
 595         struct uevent_sock *ue_sk;
 596         struct netlink_kernel_cfg cfg = {
 597                 .groups = 1,
 598                 .flags  = NL_CFG_F_NONROOT_RECV,
 599         };
 600
 601         ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);
 602         if (!ue_sk)
 603                 return -ENOMEM;
 604
 605         ue_sk->sk = netlink_kernel_create(net, NETLINK_KOBJECT_UEVENT, &cfg);
 606         if (!ue_sk->sk) {
 607                 printk(KERN_ERR
 608                        "kobject_uevent: unable to create netlink socket!\n");
 609                 kfree(ue_sk);
 610                 return -ENODEV;
 611         }
 612         mutex_lock(&uevent_sock_mutex);
 613         list_add_tail(&ue_sk->list, &uevent_sock_list);
 614         mutex_unlock(&uevent_sock_mutex);
 615         return 0;
 616 }
 617
 618 static void uevent_net_exit(struct net *net)
 619 {
 620         struct uevent_sock *ue_sk;
 621
 622         mutex_lock(&uevent_sock_mutex);
 623         list_for_each_entry(ue_sk, &uevent_sock_list, list) {
 624                 if (sock_net(ue_sk->sk) == net)
 625                         goto found;
 626         }
 627         mutex_unlock(&uevent_sock_mutex);
 628         return;
 629
 630 found:
 631         list_del(&ue_sk->list);
 632         mutex_unlock(&uevent_sock_mutex);
 633
 634         netlink_kernel_release(ue_sk->sk);
 635         kfree(ue_sk);
 636 }
 637
 638 static struct pernet_operations uevent_net_ops = {
 639         .init   = uevent_net_init,
 640         .exit   = uevent_net_exit,
 641 };
 642
 643 static int __init kobject_uevent_init(void)
 644 {
 645         return register_pernet_subsys(&uevent_net_ops);
 646 }
 647
 648
 649 postcore_initcall(kobject_uevent_init);
 650 #endif