linux/kernel/kmod.c
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   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
  46extern int max_threads;
  47
  48static struct workqueue_struct *khelper_wq;
  49
  50#define CAP_BSET        (void *)1
  51#define CAP_PI          (void *)2
  52
  53static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
  54static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
  55static DEFINE_SPINLOCK(umh_sysctl_lock);
  56static DECLARE_RWSEM(umhelper_sem);
  57
  58#ifdef CONFIG_MODULES
  59
  60/*
  61        modprobe_path is set via /proc/sys.
  62*/
  63char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
  64
  65static void free_modprobe_argv(struct subprocess_info *info)
  66{
  67        kfree(info->argv[3]); /* check call_modprobe() */
  68        kfree(info->argv);
  69}
  70
  71static 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
 102free_module_name:
 103        kfree(module_name);
 104free_argv:
 105        kfree(argv);
 106out:
 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 */
 125int __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}
 189EXPORT_SYMBOL(__request_module);
 190#endif /* CONFIG_MODULES */
 191
 192static void call_usermodehelper_freeinfo(struct subprocess_info *info)
 193{
 194        if (info->cleanup)
 195                (*info->cleanup)(info);
 196        kfree(info);
 197}
 198
 199static 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 */
 216static 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);
 259out:
 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. */
 270static 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  */
 307static 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 */
 332static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
 333
 334/* Number of helpers running */
 335static 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 */
 341static 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 */
 347static 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
 355int 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}
 383EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
 384
 385long 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}
 410EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
 411
 412void usermodehelper_read_unlock(void)
 413{
 414        up_read(&umhelper_sem);
 415}
 416EXPORT_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 */
 425void __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 */
 439int __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
 466static void helper_lock(void)
 467{
 468        atomic_inc(&running_helpers);
 469        smp_mb__after_atomic();
 470}
 471
 472static 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 */
 501struct 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}
 523EXPORT_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 */
 537int 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);
 575wait_done:
 576        retval = sub_info->retval;
 577out:
 578        call_usermodehelper_freeinfo(sub_info);
 579unlock:
 580        helper_unlock();
 581        return retval;
 582}
 583EXPORT_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 */
 598int 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}
 610EXPORT_SYMBOL(call_usermodehelper);
 611
 612static 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
 672struct 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
 690void __init usermodehelper_init(void)
 691{
 692        khelper_wq = create_singlethread_workqueue("khelper");
 693        BUG_ON(!khelper_wq);
 694}
 695
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