kernel/kmod.c

   1 /*
   2         kmod, the new module loader (replaces kerneld)
   3         Kirk Petersen
   4
   5         Reorganized not to be a daemon by Adam Richter, with guidance
   6         from Greg Zornetzer.
   7
   8         Modified to avoid chroot and file sharing problems.
   9         Mikael Pettersson
  10
  11         Limit the concurrent number of kmod modprobes to catch loops from
  12         "modprobe needs a service that is in a module".
  13         Keith Owens <kaos@ocs.com.au> December 1999
  14
  15         Unblock all signals when we exec a usermode process.
  16         Shuu Yamaguchi <shuu@wondernetworkresources.com> December 2000
  17
  18         call_usermodehelper wait flag, and remove exec_usermodehelper.
  19         Rusty Russell <rusty@rustcorp.com.au>  Jan 2003
  20 */
  21 #include <linux/module.h>
  22 #include <linux/sched.h>
  23 #include <linux/syscalls.h>
  24 #include <linux/unistd.h>
  25 #include <linux/kmod.h>
  26 #include <linux/slab.h>
  27 #include <linux/completion.h>
  28 #include <linux/cred.h>
  29 #include <linux/file.h>
  30 #include <linux/fdtable.h>
  31 #include <linux/workqueue.h>
  32 #include <linux/security.h>
  33 #include <linux/mount.h>
  34 #include <linux/kernel.h>
  35 #include <linux/init.h>
  36 #include <linux/resource.h>
  37 #include <linux/notifier.h>
  38 #include <linux/suspend.h>
  39 #include <linux/rwsem.h>
  40 #include <linux/ptrace.h>
  41 #include <linux/async.h>
  42 #include <asm/uaccess.h>
  43
  44 #include <trace/events/module.h>
  45
  46 extern int max_threads;
  47
  48 static struct workqueue_struct *khelper_wq;
  49
  50 #define CAP_BSET        (void *)1
  51 #define CAP_PI          (void *)2
  52
  53 static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
  54 static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
  55 static DEFINE_SPINLOCK(umh_sysctl_lock);
  56 static DECLARE_RWSEM(umhelper_sem);
  57
  58 #ifdef CONFIG_MODULES
  59
  60 /*
  61         modprobe_path is set via /proc/sys.
  62 */
  63 char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
  64
  65 static void free_modprobe_argv(struct subprocess_info *info)
  66 {
  67         kfree(info->argv[3]); /* check call_modprobe() */
  68         kfree(info->argv);
  69 }
  70
  71 static int call_modprobe(char *module_name, int wait)
  72 {
  73         struct subprocess_info *info;
  74         static char *envp[] = {
  75                 "HOME=/",
  76                 "TERM=linux",
  77                 "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
  78                 NULL
  79         };
  80
  81         char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL);
  82         if (!argv)
  83                 goto out;
  84
  85         module_name = kstrdup(module_name, GFP_KERNEL);
  86         if (!module_name)
  87                 goto free_argv;
  88
  89         argv[0] = modprobe_path;
  90         argv[1] = "-q";
  91         argv[2] = "--";
  92         argv[3] = module_name;  /* check free_modprobe_argv() */
  93         argv[4] = NULL;
  94
  95         info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL,
  96                                          NULL, free_modprobe_argv, NULL);
  97         if (!info)
  98                 goto free_module_name;
  99
 100         return call_usermodehelper_exec(info, wait | UMH_KILLABLE);
 101
 102 free_module_name:
 103         kfree(module_name);
 104 free_argv:
 105         kfree(argv);
 106 out:
 107         return -ENOMEM;
 108 }
 109
 110 /**
 111  * __request_module - try to load a kernel module
 112  * @wait: wait (or not) for the operation to complete
 113  * @fmt: printf style format string for the name of the module
 114  * @...: arguments as specified in the format string
 115  *
 116  * Load a module using the user mode module loader. The function returns
 117  * zero on success or a negative errno code on failure. Note that a
 118  * successful module load does not mean the module did not then unload
 119  * and exit on an error of its own. Callers must check that the service
 120  * they requested is now available not blindly invoke it.
 121  *
 122  * If module auto-loading support is disabled then this function
 123  * becomes a no-operation.
 124  */
 125 int __request_module(bool wait, const char *fmt, ...)
 126 {
 127         va_list args;
 128         char module_name[MODULE_NAME_LEN];
 129         unsigned int max_modprobes;
 130         int ret;
 131         static atomic_t kmod_concurrent = ATOMIC_INIT(0);
 132 #define MAX_KMOD_CONCURRENT 50  /* Completely arbitrary value - KAO */
 133         static int kmod_loop_msg;
 134
 135         /*
 136          * We don't allow synchronous module loading from async.  Module
 137          * init may invoke async_synchronize_full() which will end up
 138          * waiting for this task which already is waiting for the module
 139          * loading to complete, leading to a deadlock.
 140          */
 141         WARN_ON_ONCE(wait && current_is_async());
 142
 143         if (!modprobe_path[0])
 144                 return 0;
 145
 146         va_start(args, fmt);
 147         ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
 148         va_end(args);
 149         if (ret >= MODULE_NAME_LEN)
 150                 return -ENAMETOOLONG;
 151
 152         ret = security_kernel_module_request(module_name);
 153         if (ret)
 154                 return ret;
 155
 156         /* If modprobe needs a service that is in a module, we get a recursive
 157          * loop.  Limit the number of running kmod threads to max_threads/2 or
 158          * MAX_KMOD_CONCURRENT, whichever is the smaller.  A cleaner method
 159          * would be to run the parents of this process, counting how many times
 160          * kmod was invoked.  That would mean accessing the internals of the
 161          * process tables to get the command line, proc_pid_cmdline is static
 162          * and it is not worth changing the proc code just to handle this case.
 163          * KAO.
 164          *
 165          * "trace the ppid" is simple, but will fail if someone's
 166          * parent exits.  I think this is as good as it gets. --RR
 167          */
 168         max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
 169         atomic_inc(&kmod_concurrent);
 170         if (atomic_read(&kmod_concurrent) > max_modprobes) {
 171                 /* We may be blaming an innocent here, but unlikely */
 172                 if (kmod_loop_msg < 5) {
 173                         printk(KERN_ERR
 174                                "request_module: runaway loop modprobe %s\n",
 175                                module_name);
 176                         kmod_loop_msg++;
 177                 }
 178                 atomic_dec(&kmod_concurrent);
 179                 return -ENOMEM;
 180         }
 181
 182         trace_module_request(module_name, wait, _RET_IP_);
 183
 184         ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
 185
 186         atomic_dec(&kmod_concurrent);
 187         return ret;
 188 }
 189 EXPORT_SYMBOL(__request_module);
 190 #endif /* CONFIG_MODULES */
 191
 192 static void call_usermodehelper_freeinfo(struct subprocess_info *info)
 193 {
 194         if (info->cleanup)
 195                 (*info->cleanup)(info);
 196         kfree(info);
 197 }
 198
 199 static void umh_complete(struct subprocess_info *sub_info)
 200 {
 201         struct completion *comp = xchg(&sub_info->complete, NULL);
 202         /*
 203          * See call_usermodehelper_exec(). If xchg() returns NULL
 204          * we own sub_info, the UMH_KILLABLE caller has gone away
 205          * or the caller used UMH_NO_WAIT.
 206          */
 207         if (comp)
 208                 complete(comp);
 209         else
 210                 call_usermodehelper_freeinfo(sub_info);
 211 }
 212
 213 /*
 214  * This is the task which runs the usermode application
 215  */
 216 static int ____call_usermodehelper(void *data)
 217 {
 218         struct subprocess_info *sub_info = data;
 219         struct cred *new;
 220         int retval;
 221
 222         spin_lock_irq(&current->sighand->siglock);
 223         flush_signal_handlers(current, 1);
 224         spin_unlock_irq(&current->sighand->siglock);
 225
 226         /* We can run anywhere, unlike our parent keventd(). */
 227         set_cpus_allowed_ptr(current, cpu_all_mask);
 228
 229         /*
 230          * Our parent is keventd, which runs with elevated scheduling priority.
 231          * Avoid propagating that into the userspace child.
 232          */
 233         set_user_nice(current, 0);
 234
 235         retval = -ENOMEM;
 236         new = prepare_kernel_cred(current);
 237         if (!new)
 238                 goto out;
 239
 240         spin_lock(&umh_sysctl_lock);
 241         new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
 242         new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
 243                                              new->cap_inheritable);
 244         spin_unlock(&umh_sysctl_lock);
 245
 246         if (sub_info->init) {
 247                 retval = sub_info->init(sub_info, new);
 248                 if (retval) {
 249                         abort_creds(new);
 250                         goto out;
 251                 }
 252         }
 253
 254         commit_creds(new);
 255
 256         retval = do_execve(getname_kernel(sub_info->path),
 257                            (const char __user *const __user *)sub_info->argv,
 258                            (const char __user *const __user *)sub_info->envp);
 259 out:
 260         sub_info->retval = retval;
 261         /* wait_for_helper() will call umh_complete if UHM_WAIT_PROC. */
 262         if (!(sub_info->wait & UMH_WAIT_PROC))
 263                 umh_complete(sub_info);
 264         if (!retval)
 265                 return 0;
 266         do_exit(0);
 267 }
 268
 269 /* Keventd can't block, but this (a child) can. */
 270 static int wait_for_helper(void *data)
 271 {
 272         struct subprocess_info *sub_info = data;
 273         pid_t pid;
 274
 275         /* If SIGCLD is ignored sys_wait4 won't populate the status. */
 276         kernel_sigaction(SIGCHLD, SIG_DFL);
 277         pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
 278         if (pid < 0) {
 279                 sub_info->retval = pid;
 280         } else {
 281                 int ret = -ECHILD;
 282                 /*
 283                  * Normally it is bogus to call wait4() from in-kernel because
 284                  * wait4() wants to write the exit code to a userspace address.
 285                  * But wait_for_helper() always runs as keventd, and put_user()
 286                  * to a kernel address works OK for kernel threads, due to their
 287                  * having an mm_segment_t which spans the entire address space.
 288                  *
 289                  * Thus the __user pointer cast is valid here.
 290                  */
 291                 sys_wait4(pid, (int __user *)&ret, 0, NULL);
 292
 293                 /*
 294                  * If ret is 0, either ____call_usermodehelper failed and the
 295                  * real error code is already in sub_info->retval or
 296                  * sub_info->retval is 0 anyway, so don't mess with it then.
 297                  */
 298                 if (ret)
 299                         sub_info->retval = ret;
 300         }
 301
 302         umh_complete(sub_info);
 303         do_exit(0);
 304 }
 305
 306 /* This is run by khelper thread  */
 307 static void __call_usermodehelper(struct work_struct *work)
 308 {
 309         struct subprocess_info *sub_info =
 310                 container_of(work, struct subprocess_info, work);
 311         pid_t pid;
 312
 313         if (sub_info->wait & UMH_WAIT_PROC)
 314                 pid = kernel_thread(wait_for_helper, sub_info,
 315                                     CLONE_FS | CLONE_FILES | SIGCHLD);
 316         else
 317                 pid = kernel_thread(____call_usermodehelper, sub_info,
 318                                     SIGCHLD);
 319
 320         if (pid < 0) {
 321                 sub_info->retval = pid;
 322                 umh_complete(sub_info);
 323         }
 324 }
 325
 326 /*
 327  * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
 328  * (used for preventing user land processes from being created after the user
 329  * land has been frozen during a system-wide hibernation or suspend operation).
 330  * Should always be manipulated under umhelper_sem acquired for write.
 331  */
 332 static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
 333
 334 /* Number of helpers running */
 335 static atomic_t running_helpers = ATOMIC_INIT(0);
 336
 337 /*
 338  * Wait queue head used by usermodehelper_disable() to wait for all running
 339  * helpers to finish.
 340  */
 341 static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
 342
 343 /*
 344  * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
 345  * to become 'false'.
 346  */
 347 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
 348
 349 /*
 350  * Time to wait for running_helpers to become zero before the setting of
 351  * usermodehelper_disabled in usermodehelper_disable() fails
 352  */
 353 #define RUNNING_HELPERS_TIMEOUT (5 * HZ)
 354
 355 int usermodehelper_read_trylock(void)
 356 {
 357         DEFINE_WAIT(wait);
 358         int ret = 0;
 359
 360         down_read(&umhelper_sem);
 361         for (;;) {
 362                 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
 363                                 TASK_INTERRUPTIBLE);
 364                 if (!usermodehelper_disabled)
 365                         break;
 366
 367                 if (usermodehelper_disabled == UMH_DISABLED)
 368                         ret = -EAGAIN;
 369
 370                 up_read(&umhelper_sem);
 371
 372                 if (ret)
 373                         break;
 374
 375                 schedule();
 376                 try_to_freeze();
 377
 378                 down_read(&umhelper_sem);
 379         }
 380         finish_wait(&usermodehelper_disabled_waitq, &wait);
 381         return ret;
 382 }
 383 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
 384
 385 long usermodehelper_read_lock_wait(long timeout)
 386 {
 387         DEFINE_WAIT(wait);
 388
 389         if (timeout < 0)
 390                 return -EINVAL;
 391
 392         down_read(&umhelper_sem);
 393         for (;;) {
 394                 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
 395                                 TASK_UNINTERRUPTIBLE);
 396                 if (!usermodehelper_disabled)
 397                         break;
 398
 399                 up_read(&umhelper_sem);
 400
 401                 timeout = schedule_timeout(timeout);
 402                 if (!timeout)
 403                         break;
 404
 405                 down_read(&umhelper_sem);
 406         }
 407         finish_wait(&usermodehelper_disabled_waitq, &wait);
 408         return timeout;
 409 }
 410 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
 411
 412 void usermodehelper_read_unlock(void)
 413 {
 414         up_read(&umhelper_sem);
 415 }
 416 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
 417
 418 /**
 419  * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
 420  * @depth: New value to assign to usermodehelper_disabled.
 421  *
 422  * Change the value of usermodehelper_disabled (under umhelper_sem locked for
 423  * writing) and wakeup tasks waiting for it to change.
 424  */
 425 void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
 426 {
 427         down_write(&umhelper_sem);
 428         usermodehelper_disabled = depth;
 429         wake_up(&usermodehelper_disabled_waitq);
 430         up_write(&umhelper_sem);
 431 }
 432
 433 /**
 434  * __usermodehelper_disable - Prevent new helpers from being started.
 435  * @depth: New value to assign to usermodehelper_disabled.
 436  *
 437  * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
 438  */
 439 int __usermodehelper_disable(enum umh_disable_depth depth)
 440 {
 441         long retval;
 442
 443         if (!depth)
 444                 return -EINVAL;
 445
 446         down_write(&umhelper_sem);
 447         usermodehelper_disabled = depth;
 448         up_write(&umhelper_sem);
 449
 450         /*
 451          * From now on call_usermodehelper_exec() won't start any new
 452          * helpers, so it is sufficient if running_helpers turns out to
 453          * be zero at one point (it may be increased later, but that
 454          * doesn't matter).
 455          */
 456         retval = wait_event_timeout(running_helpers_waitq,
 457                                         atomic_read(&running_helpers) == 0,
 458                                         RUNNING_HELPERS_TIMEOUT);
 459         if (retval)
 460                 return 0;
 461
 462         __usermodehelper_set_disable_depth(UMH_ENABLED);
 463         return -EAGAIN;
 464 }
 465
 466 static void helper_lock(void)
 467 {
 468         atomic_inc(&running_helpers);
 469         smp_mb__after_atomic();
 470 }
 471
 472 static void helper_unlock(void)
 473 {
 474         if (atomic_dec_and_test(&running_helpers))
 475                 wake_up(&running_helpers_waitq);
 476 }
 477
 478 /**
 479  * call_usermodehelper_setup - prepare to call a usermode helper
 480  * @path: path to usermode executable
 481  * @argv: arg vector for process
 482  * @envp: environment for process
 483  * @gfp_mask: gfp mask for memory allocation
 484  * @cleanup: a cleanup function
 485  * @init: an init function
 486  * @data: arbitrary context sensitive data
 487  *
 488  * Returns either %NULL on allocation failure, or a subprocess_info
 489  * structure.  This should be passed to call_usermodehelper_exec to
 490  * exec the process and free the structure.
 491  *
 492  * The init function is used to customize the helper process prior to
 493  * exec.  A non-zero return code causes the process to error out, exit,
 494  * and return the failure to the calling process
 495  *
 496  * The cleanup function is just before ethe subprocess_info is about to
 497  * be freed.  This can be used for freeing the argv and envp.  The
 498  * Function must be runnable in either a process context or the
 499  * context in which call_usermodehelper_exec is called.
 500  */
 501 struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
 502                 char **envp, gfp_t gfp_mask,
 503                 int (*init)(struct subprocess_info *info, struct cred *new),
 504                 void (*cleanup)(struct subprocess_info *info),
 505                 void *data)
 506 {
 507         struct subprocess_info *sub_info;
 508         sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
 509         if (!sub_info)
 510                 goto out;
 511
 512         INIT_WORK(&sub_info->work, __call_usermodehelper);
 513         sub_info->path = path;
 514         sub_info->argv = argv;
 515         sub_info->envp = envp;
 516
 517         sub_info->cleanup = cleanup;
 518         sub_info->init = init;
 519         sub_info->data = data;
 520   out:
 521         return sub_info;
 522 }
 523 EXPORT_SYMBOL(call_usermodehelper_setup);
 524
 525 /**
 526  * call_usermodehelper_exec - start a usermode application
 527  * @sub_info: information about the subprocessa
 528  * @wait: wait for the application to finish and return status.
 529  *        when UMH_NO_WAIT don't wait at all, but you get no useful error back
 530  *        when the program couldn't be exec'ed. This makes it safe to call
 531  *        from interrupt context.
 532  *
 533  * Runs a user-space application.  The application is started
 534  * asynchronously if wait is not set, and runs as a child of keventd.
 535  * (ie. it runs with full root capabilities).
 536  */
 537 int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
 538 {
 539         DECLARE_COMPLETION_ONSTACK(done);
 540         int retval = 0;
 541
 542         if (!sub_info->path) {
 543                 call_usermodehelper_freeinfo(sub_info);
 544                 return -EINVAL;
 545         }
 546         helper_lock();
 547         if (!khelper_wq || usermodehelper_disabled) {
 548                 retval = -EBUSY;
 549                 goto out;
 550         }
 551         /*
 552          * Set the completion pointer only if there is a waiter.
 553          * This makes it possible to use umh_complete to free
 554          * the data structure in case of UMH_NO_WAIT.
 555          */
 556         sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done;
 557         sub_info->wait = wait;
 558
 559         queue_work(khelper_wq, &sub_info->work);
 560         if (wait == UMH_NO_WAIT)        /* task has freed sub_info */
 561                 goto unlock;
 562
 563         if (wait & UMH_KILLABLE) {
 564                 retval = wait_for_completion_killable(&done);
 565                 if (!retval)
 566                         goto wait_done;
 567
 568                 /* umh_complete() will see NULL and free sub_info */
 569                 if (xchg(&sub_info->complete, NULL))
 570                         goto unlock;
 571                 /* fallthrough, umh_complete() was already called */
 572         }
 573
 574         wait_for_completion(&done);
 575 wait_done:
 576         retval = sub_info->retval;
 577 out:
 578         call_usermodehelper_freeinfo(sub_info);
 579 unlock:
 580         helper_unlock();
 581         return retval;
 582 }
 583 EXPORT_SYMBOL(call_usermodehelper_exec);
 584
 585 /**
 586  * call_usermodehelper() - prepare and start a usermode application
 587  * @path: path to usermode executable
 588  * @argv: arg vector for process
 589  * @envp: environment for process
 590  * @wait: wait for the application to finish and return status.
 591  *        when UMH_NO_WAIT don't wait at all, but you get no useful error back
 592  *        when the program couldn't be exec'ed. This makes it safe to call
 593  *        from interrupt context.
 594  *
 595  * This function is the equivalent to use call_usermodehelper_setup() and
 596  * call_usermodehelper_exec().
 597  */
 598 int call_usermodehelper(char *path, char **argv, char **envp, int wait)
 599 {
 600         struct subprocess_info *info;
 601         gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
 602
 603         info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
 604                                          NULL, NULL, NULL);
 605         if (info == NULL)
 606                 return -ENOMEM;
 607
 608         return call_usermodehelper_exec(info, wait);
 609 }
 610 EXPORT_SYMBOL(call_usermodehelper);
 611
 612 static int proc_cap_handler(struct ctl_table *table, int write,
 613                          void __user *buffer, size_t *lenp, loff_t *ppos)
 614 {
 615         struct ctl_table t;
 616         unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
 617         kernel_cap_t new_cap;
 618         int err, i;
 619
 620         if (write && (!capable(CAP_SETPCAP) ||
 621                       !capable(CAP_SYS_MODULE)))
 622                 return -EPERM;
 623
 624         /*
 625          * convert from the global kernel_cap_t to the ulong array to print to
 626          * userspace if this is a read.
 627          */
 628         spin_lock(&umh_sysctl_lock);
 629         for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)  {
 630                 if (table->data == CAP_BSET)
 631                         cap_array[i] = usermodehelper_bset.cap[i];
 632                 else if (table->data == CAP_PI)
 633                         cap_array[i] = usermodehelper_inheritable.cap[i];
 634                 else
 635                         BUG();
 636         }
 637         spin_unlock(&umh_sysctl_lock);
 638
 639         t = *table;
 640         t.data = &cap_array;
 641
 642         /*
 643          * actually read or write and array of ulongs from userspace.  Remember
 644          * these are least significant 32 bits first
 645          */
 646         err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
 647         if (err < 0)
 648                 return err;
 649
 650         /*
 651          * convert from the sysctl array of ulongs to the kernel_cap_t
 652          * internal representation
 653          */
 654         for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
 655                 new_cap.cap[i] = cap_array[i];
 656
 657         /*
 658          * Drop everything not in the new_cap (but don't add things)
 659          */
 660         spin_lock(&umh_sysctl_lock);
 661         if (write) {
 662                 if (table->data == CAP_BSET)
 663                         usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
 664                 if (table->data == CAP_PI)
 665                         usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
 666         }
 667         spin_unlock(&umh_sysctl_lock);
 668
 669         return 0;
 670 }
 671
 672 struct ctl_table usermodehelper_table[] = {
 673         {
 674                 .procname       = "bset",
 675                 .data           = CAP_BSET,
 676                 .maxlen         = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
 677                 .mode           = 0600,
 678                 .proc_handler   = proc_cap_handler,
 679         },
 680         {
 681                 .procname       = "inheritable",
 682                 .data           = CAP_PI,
 683                 .maxlen         = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
 684                 .mode           = 0600,
 685                 .proc_handler   = proc_cap_handler,
 686         },
 687         { }
 688 };
 689
 690 void __init usermodehelper_init(void)
 691 {
 692         khelper_wq = create_singlethread_workqueue("khelper");
 693         BUG_ON(!khelper_wq);
 694 }