pid_namespace: pidns_get() should check task_active_pid_ns() != NULL
[platform/adaptation/renesas_rcar/renesas_kernel.git] / 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 /*
51  * kmod_thread_locker is used for deadlock avoidance.  There is no explicit
52  * locking to protect this global - it is private to the singleton khelper
53  * thread and should only ever be modified by that thread.
54  */
55 static const struct task_struct *kmod_thread_locker;
56
57 #define CAP_BSET        (void *)1
58 #define CAP_PI          (void *)2
59
60 static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
61 static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
62 static DEFINE_SPINLOCK(umh_sysctl_lock);
63 static DECLARE_RWSEM(umhelper_sem);
64
65 #ifdef CONFIG_MODULES
66
67 /*
68         modprobe_path is set via /proc/sys.
69 */
70 char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
71
72 static void free_modprobe_argv(struct subprocess_info *info)
73 {
74         kfree(info->argv[3]); /* check call_modprobe() */
75         kfree(info->argv);
76 }
77
78 static int call_modprobe(char *module_name, int wait)
79 {
80         struct subprocess_info *info;
81         static char *envp[] = {
82                 "HOME=/",
83                 "TERM=linux",
84                 "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
85                 NULL
86         };
87
88         char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL);
89         if (!argv)
90                 goto out;
91
92         module_name = kstrdup(module_name, GFP_KERNEL);
93         if (!module_name)
94                 goto free_argv;
95
96         argv[0] = modprobe_path;
97         argv[1] = "-q";
98         argv[2] = "--";
99         argv[3] = module_name;  /* check free_modprobe_argv() */
100         argv[4] = NULL;
101
102         info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL,
103                                          NULL, free_modprobe_argv, NULL);
104         if (!info)
105                 goto free_module_name;
106
107         return call_usermodehelper_exec(info, wait | UMH_KILLABLE);
108
109 free_module_name:
110         kfree(module_name);
111 free_argv:
112         kfree(argv);
113 out:
114         return -ENOMEM;
115 }
116
117 /**
118  * __request_module - try to load a kernel module
119  * @wait: wait (or not) for the operation to complete
120  * @fmt: printf style format string for the name of the module
121  * @...: arguments as specified in the format string
122  *
123  * Load a module using the user mode module loader. The function returns
124  * zero on success or a negative errno code on failure. Note that a
125  * successful module load does not mean the module did not then unload
126  * and exit on an error of its own. Callers must check that the service
127  * they requested is now available not blindly invoke it.
128  *
129  * If module auto-loading support is disabled then this function
130  * becomes a no-operation.
131  */
132 int __request_module(bool wait, const char *fmt, ...)
133 {
134         va_list args;
135         char module_name[MODULE_NAME_LEN];
136         unsigned int max_modprobes;
137         int ret;
138         static atomic_t kmod_concurrent = ATOMIC_INIT(0);
139 #define MAX_KMOD_CONCURRENT 50  /* Completely arbitrary value - KAO */
140         static int kmod_loop_msg;
141
142         /*
143          * We don't allow synchronous module loading from async.  Module
144          * init may invoke async_synchronize_full() which will end up
145          * waiting for this task which already is waiting for the module
146          * loading to complete, leading to a deadlock.
147          */
148         WARN_ON_ONCE(wait && current_is_async());
149
150         if (!modprobe_path[0])
151                 return 0;
152
153         va_start(args, fmt);
154         ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
155         va_end(args);
156         if (ret >= MODULE_NAME_LEN)
157                 return -ENAMETOOLONG;
158
159         ret = security_kernel_module_request(module_name);
160         if (ret)
161                 return ret;
162
163         /* If modprobe needs a service that is in a module, we get a recursive
164          * loop.  Limit the number of running kmod threads to max_threads/2 or
165          * MAX_KMOD_CONCURRENT, whichever is the smaller.  A cleaner method
166          * would be to run the parents of this process, counting how many times
167          * kmod was invoked.  That would mean accessing the internals of the
168          * process tables to get the command line, proc_pid_cmdline is static
169          * and it is not worth changing the proc code just to handle this case. 
170          * KAO.
171          *
172          * "trace the ppid" is simple, but will fail if someone's
173          * parent exits.  I think this is as good as it gets. --RR
174          */
175         max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
176         atomic_inc(&kmod_concurrent);
177         if (atomic_read(&kmod_concurrent) > max_modprobes) {
178                 /* We may be blaming an innocent here, but unlikely */
179                 if (kmod_loop_msg < 5) {
180                         printk(KERN_ERR
181                                "request_module: runaway loop modprobe %s\n",
182                                module_name);
183                         kmod_loop_msg++;
184                 }
185                 atomic_dec(&kmod_concurrent);
186                 return -ENOMEM;
187         }
188
189         trace_module_request(module_name, wait, _RET_IP_);
190
191         ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
192
193         atomic_dec(&kmod_concurrent);
194         return ret;
195 }
196 EXPORT_SYMBOL(__request_module);
197 #endif /* CONFIG_MODULES */
198
199 /*
200  * This is the task which runs the usermode application
201  */
202 static int ____call_usermodehelper(void *data)
203 {
204         struct subprocess_info *sub_info = data;
205         struct cred *new;
206         int retval;
207
208         spin_lock_irq(&current->sighand->siglock);
209         flush_signal_handlers(current, 1);
210         spin_unlock_irq(&current->sighand->siglock);
211
212         /* We can run anywhere, unlike our parent keventd(). */
213         set_cpus_allowed_ptr(current, cpu_all_mask);
214
215         /*
216          * Our parent is keventd, which runs with elevated scheduling priority.
217          * Avoid propagating that into the userspace child.
218          */
219         set_user_nice(current, 0);
220
221         retval = -ENOMEM;
222         new = prepare_kernel_cred(current);
223         if (!new)
224                 goto fail;
225
226         spin_lock(&umh_sysctl_lock);
227         new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
228         new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
229                                              new->cap_inheritable);
230         spin_unlock(&umh_sysctl_lock);
231
232         if (sub_info->init) {
233                 retval = sub_info->init(sub_info, new);
234                 if (retval) {
235                         abort_creds(new);
236                         goto fail;
237                 }
238         }
239
240         commit_creds(new);
241
242         retval = do_execve(getname_kernel(sub_info->path),
243                            (const char __user *const __user *)sub_info->argv,
244                            (const char __user *const __user *)sub_info->envp);
245         if (!retval)
246                 return 0;
247
248         /* Exec failed? */
249 fail:
250         sub_info->retval = retval;
251         do_exit(0);
252 }
253
254 static int call_helper(void *data)
255 {
256         /* Worker thread started blocking khelper thread. */
257         kmod_thread_locker = current;
258         return ____call_usermodehelper(data);
259 }
260
261 static void call_usermodehelper_freeinfo(struct subprocess_info *info)
262 {
263         if (info->cleanup)
264                 (*info->cleanup)(info);
265         kfree(info);
266 }
267
268 static void umh_complete(struct subprocess_info *sub_info)
269 {
270         struct completion *comp = xchg(&sub_info->complete, NULL);
271         /*
272          * See call_usermodehelper_exec(). If xchg() returns NULL
273          * we own sub_info, the UMH_KILLABLE caller has gone away.
274          */
275         if (comp)
276                 complete(comp);
277         else
278                 call_usermodehelper_freeinfo(sub_info);
279 }
280
281 /* Keventd can't block, but this (a child) can. */
282 static int wait_for_helper(void *data)
283 {
284         struct subprocess_info *sub_info = data;
285         pid_t pid;
286
287         /* If SIGCLD is ignored sys_wait4 won't populate the status. */
288         spin_lock_irq(&current->sighand->siglock);
289         current->sighand->action[SIGCHLD-1].sa.sa_handler = SIG_DFL;
290         spin_unlock_irq(&current->sighand->siglock);
291
292         pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
293         if (pid < 0) {
294                 sub_info->retval = pid;
295         } else {
296                 int ret = -ECHILD;
297                 /*
298                  * Normally it is bogus to call wait4() from in-kernel because
299                  * wait4() wants to write the exit code to a userspace address.
300                  * But wait_for_helper() always runs as keventd, and put_user()
301                  * to a kernel address works OK for kernel threads, due to their
302                  * having an mm_segment_t which spans the entire address space.
303                  *
304                  * Thus the __user pointer cast is valid here.
305                  */
306                 sys_wait4(pid, (int __user *)&ret, 0, NULL);
307
308                 /*
309                  * If ret is 0, either ____call_usermodehelper failed and the
310                  * real error code is already in sub_info->retval or
311                  * sub_info->retval is 0 anyway, so don't mess with it then.
312                  */
313                 if (ret)
314                         sub_info->retval = ret;
315         }
316
317         umh_complete(sub_info);
318         do_exit(0);
319 }
320
321 /* This is run by khelper thread  */
322 static void __call_usermodehelper(struct work_struct *work)
323 {
324         struct subprocess_info *sub_info =
325                 container_of(work, struct subprocess_info, work);
326         int wait = sub_info->wait & ~UMH_KILLABLE;
327         pid_t pid;
328
329         /* CLONE_VFORK: wait until the usermode helper has execve'd
330          * successfully We need the data structures to stay around
331          * until that is done.  */
332         if (wait == UMH_WAIT_PROC)
333                 pid = kernel_thread(wait_for_helper, sub_info,
334                                     CLONE_FS | CLONE_FILES | SIGCHLD);
335         else {
336                 pid = kernel_thread(call_helper, sub_info,
337                                     CLONE_VFORK | SIGCHLD);
338                 /* Worker thread stopped blocking khelper thread. */
339                 kmod_thread_locker = NULL;
340         }
341
342         switch (wait) {
343         case UMH_NO_WAIT:
344                 call_usermodehelper_freeinfo(sub_info);
345                 break;
346
347         case UMH_WAIT_PROC:
348                 if (pid > 0)
349                         break;
350                 /* FALLTHROUGH */
351         case UMH_WAIT_EXEC:
352                 if (pid < 0)
353                         sub_info->retval = pid;
354                 umh_complete(sub_info);
355         }
356 }
357
358 /*
359  * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
360  * (used for preventing user land processes from being created after the user
361  * land has been frozen during a system-wide hibernation or suspend operation).
362  * Should always be manipulated under umhelper_sem acquired for write.
363  */
364 static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
365
366 /* Number of helpers running */
367 static atomic_t running_helpers = ATOMIC_INIT(0);
368
369 /*
370  * Wait queue head used by usermodehelper_disable() to wait for all running
371  * helpers to finish.
372  */
373 static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
374
375 /*
376  * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
377  * to become 'false'.
378  */
379 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
380
381 /*
382  * Time to wait for running_helpers to become zero before the setting of
383  * usermodehelper_disabled in usermodehelper_disable() fails
384  */
385 #define RUNNING_HELPERS_TIMEOUT (5 * HZ)
386
387 int usermodehelper_read_trylock(void)
388 {
389         DEFINE_WAIT(wait);
390         int ret = 0;
391
392         down_read(&umhelper_sem);
393         for (;;) {
394                 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
395                                 TASK_INTERRUPTIBLE);
396                 if (!usermodehelper_disabled)
397                         break;
398
399                 if (usermodehelper_disabled == UMH_DISABLED)
400                         ret = -EAGAIN;
401
402                 up_read(&umhelper_sem);
403
404                 if (ret)
405                         break;
406
407                 schedule();
408                 try_to_freeze();
409
410                 down_read(&umhelper_sem);
411         }
412         finish_wait(&usermodehelper_disabled_waitq, &wait);
413         return ret;
414 }
415 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
416
417 long usermodehelper_read_lock_wait(long timeout)
418 {
419         DEFINE_WAIT(wait);
420
421         if (timeout < 0)
422                 return -EINVAL;
423
424         down_read(&umhelper_sem);
425         for (;;) {
426                 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
427                                 TASK_UNINTERRUPTIBLE);
428                 if (!usermodehelper_disabled)
429                         break;
430
431                 up_read(&umhelper_sem);
432
433                 timeout = schedule_timeout(timeout);
434                 if (!timeout)
435                         break;
436
437                 down_read(&umhelper_sem);
438         }
439         finish_wait(&usermodehelper_disabled_waitq, &wait);
440         return timeout;
441 }
442 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
443
444 void usermodehelper_read_unlock(void)
445 {
446         up_read(&umhelper_sem);
447 }
448 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
449
450 /**
451  * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
452  * @depth: New value to assign to usermodehelper_disabled.
453  *
454  * Change the value of usermodehelper_disabled (under umhelper_sem locked for
455  * writing) and wakeup tasks waiting for it to change.
456  */
457 void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
458 {
459         down_write(&umhelper_sem);
460         usermodehelper_disabled = depth;
461         wake_up(&usermodehelper_disabled_waitq);
462         up_write(&umhelper_sem);
463 }
464
465 /**
466  * __usermodehelper_disable - Prevent new helpers from being started.
467  * @depth: New value to assign to usermodehelper_disabled.
468  *
469  * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
470  */
471 int __usermodehelper_disable(enum umh_disable_depth depth)
472 {
473         long retval;
474
475         if (!depth)
476                 return -EINVAL;
477
478         down_write(&umhelper_sem);
479         usermodehelper_disabled = depth;
480         up_write(&umhelper_sem);
481
482         /*
483          * From now on call_usermodehelper_exec() won't start any new
484          * helpers, so it is sufficient if running_helpers turns out to
485          * be zero at one point (it may be increased later, but that
486          * doesn't matter).
487          */
488         retval = wait_event_timeout(running_helpers_waitq,
489                                         atomic_read(&running_helpers) == 0,
490                                         RUNNING_HELPERS_TIMEOUT);
491         if (retval)
492                 return 0;
493
494         __usermodehelper_set_disable_depth(UMH_ENABLED);
495         return -EAGAIN;
496 }
497
498 static void helper_lock(void)
499 {
500         atomic_inc(&running_helpers);
501         smp_mb__after_atomic_inc();
502 }
503
504 static void helper_unlock(void)
505 {
506         if (atomic_dec_and_test(&running_helpers))
507                 wake_up(&running_helpers_waitq);
508 }
509
510 /**
511  * call_usermodehelper_setup - prepare to call a usermode helper
512  * @path: path to usermode executable
513  * @argv: arg vector for process
514  * @envp: environment for process
515  * @gfp_mask: gfp mask for memory allocation
516  * @cleanup: a cleanup function
517  * @init: an init function
518  * @data: arbitrary context sensitive data
519  *
520  * Returns either %NULL on allocation failure, or a subprocess_info
521  * structure.  This should be passed to call_usermodehelper_exec to
522  * exec the process and free the structure.
523  *
524  * The init function is used to customize the helper process prior to
525  * exec.  A non-zero return code causes the process to error out, exit,
526  * and return the failure to the calling process
527  *
528  * The cleanup function is just before ethe subprocess_info is about to
529  * be freed.  This can be used for freeing the argv and envp.  The
530  * Function must be runnable in either a process context or the
531  * context in which call_usermodehelper_exec is called.
532  */
533 struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
534                 char **envp, gfp_t gfp_mask,
535                 int (*init)(struct subprocess_info *info, struct cred *new),
536                 void (*cleanup)(struct subprocess_info *info),
537                 void *data)
538 {
539         struct subprocess_info *sub_info;
540         sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
541         if (!sub_info)
542                 goto out;
543
544         INIT_WORK(&sub_info->work, __call_usermodehelper);
545         sub_info->path = path;
546         sub_info->argv = argv;
547         sub_info->envp = envp;
548
549         sub_info->cleanup = cleanup;
550         sub_info->init = init;
551         sub_info->data = data;
552   out:
553         return sub_info;
554 }
555 EXPORT_SYMBOL(call_usermodehelper_setup);
556
557 /**
558  * call_usermodehelper_exec - start a usermode application
559  * @sub_info: information about the subprocessa
560  * @wait: wait for the application to finish and return status.
561  *        when UMH_NO_WAIT don't wait at all, but you get no useful error back
562  *        when the program couldn't be exec'ed. This makes it safe to call
563  *        from interrupt context.
564  *
565  * Runs a user-space application.  The application is started
566  * asynchronously if wait is not set, and runs as a child of keventd.
567  * (ie. it runs with full root capabilities).
568  */
569 int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
570 {
571         DECLARE_COMPLETION_ONSTACK(done);
572         int retval = 0;
573
574         if (!sub_info->path) {
575                 call_usermodehelper_freeinfo(sub_info);
576                 return -EINVAL;
577         }
578         helper_lock();
579         if (!khelper_wq || usermodehelper_disabled) {
580                 retval = -EBUSY;
581                 goto out;
582         }
583         /*
584          * Worker thread must not wait for khelper thread at below
585          * wait_for_completion() if the thread was created with CLONE_VFORK
586          * flag, for khelper thread is already waiting for the thread at
587          * wait_for_completion() in do_fork().
588          */
589         if (wait != UMH_NO_WAIT && current == kmod_thread_locker) {
590                 retval = -EBUSY;
591                 goto out;
592         }
593
594         sub_info->complete = &done;
595         sub_info->wait = wait;
596
597         queue_work(khelper_wq, &sub_info->work);
598         if (wait == UMH_NO_WAIT)        /* task has freed sub_info */
599                 goto unlock;
600
601         if (wait & UMH_KILLABLE) {
602                 retval = wait_for_completion_killable(&done);
603                 if (!retval)
604                         goto wait_done;
605
606                 /* umh_complete() will see NULL and free sub_info */
607                 if (xchg(&sub_info->complete, NULL))
608                         goto unlock;
609                 /* fallthrough, umh_complete() was already called */
610         }
611
612         wait_for_completion(&done);
613 wait_done:
614         retval = sub_info->retval;
615 out:
616         call_usermodehelper_freeinfo(sub_info);
617 unlock:
618         helper_unlock();
619         return retval;
620 }
621 EXPORT_SYMBOL(call_usermodehelper_exec);
622
623 /**
624  * call_usermodehelper() - prepare and start a usermode application
625  * @path: path to usermode executable
626  * @argv: arg vector for process
627  * @envp: environment for process
628  * @wait: wait for the application to finish and return status.
629  *        when UMH_NO_WAIT don't wait at all, but you get no useful error back
630  *        when the program couldn't be exec'ed. This makes it safe to call
631  *        from interrupt context.
632  *
633  * This function is the equivalent to use call_usermodehelper_setup() and
634  * call_usermodehelper_exec().
635  */
636 int call_usermodehelper(char *path, char **argv, char **envp, int wait)
637 {
638         struct subprocess_info *info;
639         gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
640
641         info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
642                                          NULL, NULL, NULL);
643         if (info == NULL)
644                 return -ENOMEM;
645
646         return call_usermodehelper_exec(info, wait);
647 }
648 EXPORT_SYMBOL(call_usermodehelper);
649
650 static int proc_cap_handler(struct ctl_table *table, int write,
651                          void __user *buffer, size_t *lenp, loff_t *ppos)
652 {
653         struct ctl_table t;
654         unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
655         kernel_cap_t new_cap;
656         int err, i;
657
658         if (write && (!capable(CAP_SETPCAP) ||
659                       !capable(CAP_SYS_MODULE)))
660                 return -EPERM;
661
662         /*
663          * convert from the global kernel_cap_t to the ulong array to print to
664          * userspace if this is a read.
665          */
666         spin_lock(&umh_sysctl_lock);
667         for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)  {
668                 if (table->data == CAP_BSET)
669                         cap_array[i] = usermodehelper_bset.cap[i];
670                 else if (table->data == CAP_PI)
671                         cap_array[i] = usermodehelper_inheritable.cap[i];
672                 else
673                         BUG();
674         }
675         spin_unlock(&umh_sysctl_lock);
676
677         t = *table;
678         t.data = &cap_array;
679
680         /*
681          * actually read or write and array of ulongs from userspace.  Remember
682          * these are least significant 32 bits first
683          */
684         err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
685         if (err < 0)
686                 return err;
687
688         /*
689          * convert from the sysctl array of ulongs to the kernel_cap_t
690          * internal representation
691          */
692         for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
693                 new_cap.cap[i] = cap_array[i];
694
695         /*
696          * Drop everything not in the new_cap (but don't add things)
697          */
698         spin_lock(&umh_sysctl_lock);
699         if (write) {
700                 if (table->data == CAP_BSET)
701                         usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
702                 if (table->data == CAP_PI)
703                         usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
704         }
705         spin_unlock(&umh_sysctl_lock);
706
707         return 0;
708 }
709
710 struct ctl_table usermodehelper_table[] = {
711         {
712                 .procname       = "bset",
713                 .data           = CAP_BSET,
714                 .maxlen         = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
715                 .mode           = 0600,
716                 .proc_handler   = proc_cap_handler,
717         },
718         {
719                 .procname       = "inheritable",
720                 .data           = CAP_PI,
721                 .maxlen         = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
722                 .mode           = 0600,
723                 .proc_handler   = proc_cap_handler,
724         },
725         { }
726 };
727
728 void __init usermodehelper_init(void)
729 {
730         khelper_wq = create_singlethread_workqueue("khelper");
731         BUG_ON(!khelper_wq);
732 }