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TOMOYO Linux Cross Reference
Linux/kernel/umh.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * umh - the kernel usermode helper
  4  */
  5 #include <linux/module.h>
  6 #include <linux/sched.h>
  7 #include <linux/sched/task.h>
  8 #include <linux/binfmts.h>
  9 #include <linux/syscalls.h>
 10 #include <linux/unistd.h>
 11 #include <linux/kmod.h>
 12 #include <linux/slab.h>
 13 #include <linux/completion.h>
 14 #include <linux/cred.h>
 15 #include <linux/file.h>
 16 #include <linux/fdtable.h>
 17 #include <linux/workqueue.h>
 18 #include <linux/security.h>
 19 #include <linux/mount.h>
 20 #include <linux/kernel.h>
 21 #include <linux/init.h>
 22 #include <linux/resource.h>
 23 #include <linux/notifier.h>
 24 #include <linux/suspend.h>
 25 #include <linux/rwsem.h>
 26 #include <linux/ptrace.h>
 27 #include <linux/async.h>
 28 #include <linux/uaccess.h>
 29 #include <linux/shmem_fs.h>
 30 #include <linux/pipe_fs_i.h>
 31 
 32 #include <trace/events/module.h>
 33 
 34 #define CAP_BSET        (void *)1
 35 #define CAP_PI          (void *)2
 36 
 37 static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
 38 static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
 39 static DEFINE_SPINLOCK(umh_sysctl_lock);
 40 static DECLARE_RWSEM(umhelper_sem);
 41 static LIST_HEAD(umh_list);
 42 static DEFINE_MUTEX(umh_list_lock);
 43 
 44 static void call_usermodehelper_freeinfo(struct subprocess_info *info)
 45 {
 46         if (info->cleanup)
 47                 (*info->cleanup)(info);
 48         kfree(info);
 49 }
 50 
 51 static void umh_complete(struct subprocess_info *sub_info)
 52 {
 53         struct completion *comp = xchg(&sub_info->complete, NULL);
 54         /*
 55          * See call_usermodehelper_exec(). If xchg() returns NULL
 56          * we own sub_info, the UMH_KILLABLE caller has gone away
 57          * or the caller used UMH_NO_WAIT.
 58          */
 59         if (comp)
 60                 complete(comp);
 61         else
 62                 call_usermodehelper_freeinfo(sub_info);
 63 }
 64 
 65 /*
 66  * This is the task which runs the usermode application
 67  */
 68 static int call_usermodehelper_exec_async(void *data)
 69 {
 70         struct subprocess_info *sub_info = data;
 71         struct cred *new;
 72         int retval;
 73 
 74         spin_lock_irq(&current->sighand->siglock);
 75         flush_signal_handlers(current, 1);
 76         spin_unlock_irq(&current->sighand->siglock);
 77 
 78         /*
 79          * Our parent (unbound workqueue) runs with elevated scheduling
 80          * priority. Avoid propagating that into the userspace child.
 81          */
 82         set_user_nice(current, 0);
 83 
 84         retval = -ENOMEM;
 85         new = prepare_kernel_cred(current);
 86         if (!new)
 87                 goto out;
 88 
 89         spin_lock(&umh_sysctl_lock);
 90         new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
 91         new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
 92                                              new->cap_inheritable);
 93         spin_unlock(&umh_sysctl_lock);
 94 
 95         if (sub_info->init) {
 96                 retval = sub_info->init(sub_info, new);
 97                 if (retval) {
 98                         abort_creds(new);
 99                         goto out;
100                 }
101         }
102 
103         commit_creds(new);
104 
105         sub_info->pid = task_pid_nr(current);
106         if (sub_info->file) {
107                 retval = do_execve_file(sub_info->file,
108                                         sub_info->argv, sub_info->envp);
109                 if (!retval)
110                         current->flags |= PF_UMH;
111         } else
112                 retval = do_execve(getname_kernel(sub_info->path),
113                                    (const char __user *const __user *)sub_info->argv,
114                                    (const char __user *const __user *)sub_info->envp);
115 out:
116         sub_info->retval = retval;
117         /*
118          * call_usermodehelper_exec_sync() will call umh_complete
119          * if UHM_WAIT_PROC.
120          */
121         if (!(sub_info->wait & UMH_WAIT_PROC))
122                 umh_complete(sub_info);
123         if (!retval)
124                 return 0;
125         do_exit(0);
126 }
127 
128 /* Handles UMH_WAIT_PROC.  */
129 static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
130 {
131         pid_t pid;
132 
133         /* If SIGCLD is ignored kernel_wait4 won't populate the status. */
134         kernel_sigaction(SIGCHLD, SIG_DFL);
135         pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD);
136         if (pid < 0) {
137                 sub_info->retval = pid;
138         } else {
139                 int ret = -ECHILD;
140                 /*
141                  * Normally it is bogus to call wait4() from in-kernel because
142                  * wait4() wants to write the exit code to a userspace address.
143                  * But call_usermodehelper_exec_sync() always runs as kernel
144                  * thread (workqueue) and put_user() to a kernel address works
145                  * OK for kernel threads, due to their having an mm_segment_t
146                  * which spans the entire address space.
147                  *
148                  * Thus the __user pointer cast is valid here.
149                  */
150                 kernel_wait4(pid, (int __user *)&ret, 0, NULL);
151 
152                 /*
153                  * If ret is 0, either call_usermodehelper_exec_async failed and
154                  * the real error code is already in sub_info->retval or
155                  * sub_info->retval is 0 anyway, so don't mess with it then.
156                  */
157                 if (ret)
158                         sub_info->retval = ret;
159         }
160 
161         /* Restore default kernel sig handler */
162         kernel_sigaction(SIGCHLD, SIG_IGN);
163 
164         umh_complete(sub_info);
165 }
166 
167 /*
168  * We need to create the usermodehelper kernel thread from a task that is affine
169  * to an optimized set of CPUs (or nohz housekeeping ones) such that they
170  * inherit a widest affinity irrespective of call_usermodehelper() callers with
171  * possibly reduced affinity (eg: per-cpu workqueues). We don't want
172  * usermodehelper targets to contend a busy CPU.
173  *
174  * Unbound workqueues provide such wide affinity and allow to block on
175  * UMH_WAIT_PROC requests without blocking pending request (up to some limit).
176  *
177  * Besides, workqueues provide the privilege level that caller might not have
178  * to perform the usermodehelper request.
179  *
180  */
181 static void call_usermodehelper_exec_work(struct work_struct *work)
182 {
183         struct subprocess_info *sub_info =
184                 container_of(work, struct subprocess_info, work);
185 
186         if (sub_info->wait & UMH_WAIT_PROC) {
187                 call_usermodehelper_exec_sync(sub_info);
188         } else {
189                 pid_t pid;
190                 /*
191                  * Use CLONE_PARENT to reparent it to kthreadd; we do not
192                  * want to pollute current->children, and we need a parent
193                  * that always ignores SIGCHLD to ensure auto-reaping.
194                  */
195                 pid = kernel_thread(call_usermodehelper_exec_async, sub_info,
196                                     CLONE_PARENT | SIGCHLD);
197                 if (pid < 0) {
198                         sub_info->retval = pid;
199                         umh_complete(sub_info);
200                 }
201         }
202 }
203 
204 /*
205  * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
206  * (used for preventing user land processes from being created after the user
207  * land has been frozen during a system-wide hibernation or suspend operation).
208  * Should always be manipulated under umhelper_sem acquired for write.
209  */
210 static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
211 
212 /* Number of helpers running */
213 static atomic_t running_helpers = ATOMIC_INIT(0);
214 
215 /*
216  * Wait queue head used by usermodehelper_disable() to wait for all running
217  * helpers to finish.
218  */
219 static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
220 
221 /*
222  * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
223  * to become 'false'.
224  */
225 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
226 
227 /*
228  * Time to wait for running_helpers to become zero before the setting of
229  * usermodehelper_disabled in usermodehelper_disable() fails
230  */
231 #define RUNNING_HELPERS_TIMEOUT (5 * HZ)
232 
233 int usermodehelper_read_trylock(void)
234 {
235         DEFINE_WAIT(wait);
236         int ret = 0;
237 
238         down_read(&umhelper_sem);
239         for (;;) {
240                 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
241                                 TASK_INTERRUPTIBLE);
242                 if (!usermodehelper_disabled)
243                         break;
244 
245                 if (usermodehelper_disabled == UMH_DISABLED)
246                         ret = -EAGAIN;
247 
248                 up_read(&umhelper_sem);
249 
250                 if (ret)
251                         break;
252 
253                 schedule();
254                 try_to_freeze();
255 
256                 down_read(&umhelper_sem);
257         }
258         finish_wait(&usermodehelper_disabled_waitq, &wait);
259         return ret;
260 }
261 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
262 
263 long usermodehelper_read_lock_wait(long timeout)
264 {
265         DEFINE_WAIT(wait);
266 
267         if (timeout < 0)
268                 return -EINVAL;
269 
270         down_read(&umhelper_sem);
271         for (;;) {
272                 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
273                                 TASK_UNINTERRUPTIBLE);
274                 if (!usermodehelper_disabled)
275                         break;
276 
277                 up_read(&umhelper_sem);
278 
279                 timeout = schedule_timeout(timeout);
280                 if (!timeout)
281                         break;
282 
283                 down_read(&umhelper_sem);
284         }
285         finish_wait(&usermodehelper_disabled_waitq, &wait);
286         return timeout;
287 }
288 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
289 
290 void usermodehelper_read_unlock(void)
291 {
292         up_read(&umhelper_sem);
293 }
294 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
295 
296 /**
297  * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
298  * @depth: New value to assign to usermodehelper_disabled.
299  *
300  * Change the value of usermodehelper_disabled (under umhelper_sem locked for
301  * writing) and wakeup tasks waiting for it to change.
302  */
303 void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
304 {
305         down_write(&umhelper_sem);
306         usermodehelper_disabled = depth;
307         wake_up(&usermodehelper_disabled_waitq);
308         up_write(&umhelper_sem);
309 }
310 
311 /**
312  * __usermodehelper_disable - Prevent new helpers from being started.
313  * @depth: New value to assign to usermodehelper_disabled.
314  *
315  * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
316  */
317 int __usermodehelper_disable(enum umh_disable_depth depth)
318 {
319         long retval;
320 
321         if (!depth)
322                 return -EINVAL;
323 
324         down_write(&umhelper_sem);
325         usermodehelper_disabled = depth;
326         up_write(&umhelper_sem);
327 
328         /*
329          * From now on call_usermodehelper_exec() won't start any new
330          * helpers, so it is sufficient if running_helpers turns out to
331          * be zero at one point (it may be increased later, but that
332          * doesn't matter).
333          */
334         retval = wait_event_timeout(running_helpers_waitq,
335                                         atomic_read(&running_helpers) == 0,
336                                         RUNNING_HELPERS_TIMEOUT);
337         if (retval)
338                 return 0;
339 
340         __usermodehelper_set_disable_depth(UMH_ENABLED);
341         return -EAGAIN;
342 }
343 
344 static void helper_lock(void)
345 {
346         atomic_inc(&running_helpers);
347         smp_mb__after_atomic();
348 }
349 
350 static void helper_unlock(void)
351 {
352         if (atomic_dec_and_test(&running_helpers))
353                 wake_up(&running_helpers_waitq);
354 }
355 
356 /**
357  * call_usermodehelper_setup - prepare to call a usermode helper
358  * @path: path to usermode executable
359  * @argv: arg vector for process
360  * @envp: environment for process
361  * @gfp_mask: gfp mask for memory allocation
362  * @cleanup: a cleanup function
363  * @init: an init function
364  * @data: arbitrary context sensitive data
365  *
366  * Returns either %NULL on allocation failure, or a subprocess_info
367  * structure.  This should be passed to call_usermodehelper_exec to
368  * exec the process and free the structure.
369  *
370  * The init function is used to customize the helper process prior to
371  * exec.  A non-zero return code causes the process to error out, exit,
372  * and return the failure to the calling process
373  *
374  * The cleanup function is just before ethe subprocess_info is about to
375  * be freed.  This can be used for freeing the argv and envp.  The
376  * Function must be runnable in either a process context or the
377  * context in which call_usermodehelper_exec is called.
378  */
379 struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv,
380                 char **envp, gfp_t gfp_mask,
381                 int (*init)(struct subprocess_info *info, struct cred *new),
382                 void (*cleanup)(struct subprocess_info *info),
383                 void *data)
384 {
385         struct subprocess_info *sub_info;
386         sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
387         if (!sub_info)
388                 goto out;
389 
390         INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
391 
392 #ifdef CONFIG_STATIC_USERMODEHELPER
393         sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH;
394 #else
395         sub_info->path = path;
396 #endif
397         sub_info->argv = argv;
398         sub_info->envp = envp;
399 
400         sub_info->cleanup = cleanup;
401         sub_info->init = init;
402         sub_info->data = data;
403   out:
404         return sub_info;
405 }
406 EXPORT_SYMBOL(call_usermodehelper_setup);
407 
408 struct subprocess_info *call_usermodehelper_setup_file(struct file *file,
409                 int (*init)(struct subprocess_info *info, struct cred *new),
410                 void (*cleanup)(struct subprocess_info *info), void *data)
411 {
412         struct subprocess_info *sub_info;
413         struct umh_info *info = data;
414         const char *cmdline = (info->cmdline) ? info->cmdline : "usermodehelper";
415 
416         sub_info = kzalloc(sizeof(struct subprocess_info), GFP_KERNEL);
417         if (!sub_info)
418                 return NULL;
419 
420         sub_info->argv = argv_split(GFP_KERNEL, cmdline, NULL);
421         if (!sub_info->argv) {
422                 kfree(sub_info);
423                 return NULL;
424         }
425 
426         INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
427         sub_info->path = "none";
428         sub_info->file = file;
429         sub_info->init = init;
430         sub_info->cleanup = cleanup;
431         sub_info->data = data;
432         return sub_info;
433 }
434 
435 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
436 {
437         struct umh_info *umh_info = info->data;
438         struct file *from_umh[2];
439         struct file *to_umh[2];
440         int err;
441 
442         /* create pipe to send data to umh */
443         err = create_pipe_files(to_umh, 0);
444         if (err)
445                 return err;
446         err = replace_fd(0, to_umh[0], 0);
447         fput(to_umh[0]);
448         if (err < 0) {
449                 fput(to_umh[1]);
450                 return err;
451         }
452 
453         /* create pipe to receive data from umh */
454         err = create_pipe_files(from_umh, 0);
455         if (err) {
456                 fput(to_umh[1]);
457                 replace_fd(0, NULL, 0);
458                 return err;
459         }
460         err = replace_fd(1, from_umh[1], 0);
461         fput(from_umh[1]);
462         if (err < 0) {
463                 fput(to_umh[1]);
464                 replace_fd(0, NULL, 0);
465                 fput(from_umh[0]);
466                 return err;
467         }
468 
469         umh_info->pipe_to_umh = to_umh[1];
470         umh_info->pipe_from_umh = from_umh[0];
471         return 0;
472 }
473 
474 static void umh_clean_and_save_pid(struct subprocess_info *info)
475 {
476         struct umh_info *umh_info = info->data;
477 
478         argv_free(info->argv);
479         umh_info->pid = info->pid;
480 }
481 
482 /**
483  * fork_usermode_blob - fork a blob of bytes as a usermode process
484  * @data: a blob of bytes that can be do_execv-ed as a file
485  * @len: length of the blob
486  * @info: information about usermode process (shouldn't be NULL)
487  *
488  * If info->cmdline is set it will be used as command line for the
489  * user process, else "usermodehelper" is used.
490  *
491  * Returns either negative error or zero which indicates success
492  * in executing a blob of bytes as a usermode process. In such
493  * case 'struct umh_info *info' is populated with two pipes
494  * and a pid of the process. The caller is responsible for health
495  * check of the user process, killing it via pid, and closing the
496  * pipes when user process is no longer needed.
497  */
498 int fork_usermode_blob(void *data, size_t len, struct umh_info *info)
499 {
500         struct subprocess_info *sub_info;
501         struct file *file;
502         ssize_t written;
503         loff_t pos = 0;
504         int err;
505 
506         file = shmem_kernel_file_setup("", len, 0);
507         if (IS_ERR(file))
508                 return PTR_ERR(file);
509 
510         written = kernel_write(file, data, len, &pos);
511         if (written != len) {
512                 err = written;
513                 if (err >= 0)
514                         err = -ENOMEM;
515                 goto out;
516         }
517 
518         err = -ENOMEM;
519         sub_info = call_usermodehelper_setup_file(file, umh_pipe_setup,
520                                                   umh_clean_and_save_pid, info);
521         if (!sub_info)
522                 goto out;
523 
524         err = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);
525         if (!err) {
526                 mutex_lock(&umh_list_lock);
527                 list_add(&info->list, &umh_list);
528                 mutex_unlock(&umh_list_lock);
529         }
530 out:
531         fput(file);
532         return err;
533 }
534 EXPORT_SYMBOL_GPL(fork_usermode_blob);
535 
536 /**
537  * call_usermodehelper_exec - start a usermode application
538  * @sub_info: information about the subprocessa
539  * @wait: wait for the application to finish and return status.
540  *        when UMH_NO_WAIT don't wait at all, but you get no useful error back
541  *        when the program couldn't be exec'ed. This makes it safe to call
542  *        from interrupt context.
543  *
544  * Runs a user-space application.  The application is started
545  * asynchronously if wait is not set, and runs as a child of system workqueues.
546  * (ie. it runs with full root capabilities and optimized affinity).
547  */
548 int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
549 {
550         DECLARE_COMPLETION_ONSTACK(done);
551         int retval = 0;
552 
553         if (!sub_info->path) {
554                 call_usermodehelper_freeinfo(sub_info);
555                 return -EINVAL;
556         }
557         helper_lock();
558         if (usermodehelper_disabled) {
559                 retval = -EBUSY;
560                 goto out;
561         }
562 
563         /*
564          * If there is no binary for us to call, then just return and get out of
565          * here.  This allows us to set STATIC_USERMODEHELPER_PATH to "" and
566          * disable all call_usermodehelper() calls.
567          */
568         if (strlen(sub_info->path) == 0)
569                 goto out;
570 
571         /*
572          * Set the completion pointer only if there is a waiter.
573          * This makes it possible to use umh_complete to free
574          * the data structure in case of UMH_NO_WAIT.
575          */
576         sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done;
577         sub_info->wait = wait;
578 
579         queue_work(system_unbound_wq, &sub_info->work);
580         if (wait == UMH_NO_WAIT)        /* task has freed sub_info */
581                 goto unlock;
582 
583         if (wait & UMH_KILLABLE) {
584                 retval = wait_for_completion_killable(&done);
585                 if (!retval)
586                         goto wait_done;
587 
588                 /* umh_complete() will see NULL and free sub_info */
589                 if (xchg(&sub_info->complete, NULL))
590                         goto unlock;
591                 /* fallthrough, umh_complete() was already called */
592         }
593 
594         wait_for_completion(&done);
595 wait_done:
596         retval = sub_info->retval;
597 out:
598         call_usermodehelper_freeinfo(sub_info);
599 unlock:
600         helper_unlock();
601         return retval;
602 }
603 EXPORT_SYMBOL(call_usermodehelper_exec);
604 
605 /**
606  * call_usermodehelper() - prepare and start a usermode application
607  * @path: path to usermode executable
608  * @argv: arg vector for process
609  * @envp: environment for process
610  * @wait: wait for the application to finish and return status.
611  *        when UMH_NO_WAIT don't wait at all, but you get no useful error back
612  *        when the program couldn't be exec'ed. This makes it safe to call
613  *        from interrupt context.
614  *
615  * This function is the equivalent to use call_usermodehelper_setup() and
616  * call_usermodehelper_exec().
617  */
618 int call_usermodehelper(const char *path, char **argv, char **envp, int wait)
619 {
620         struct subprocess_info *info;
621         gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
622 
623         info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
624                                          NULL, NULL, NULL);
625         if (info == NULL)
626                 return -ENOMEM;
627 
628         return call_usermodehelper_exec(info, wait);
629 }
630 EXPORT_SYMBOL(call_usermodehelper);
631 
632 static int proc_cap_handler(struct ctl_table *table, int write,
633                          void __user *buffer, size_t *lenp, loff_t *ppos)
634 {
635         struct ctl_table t;
636         unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
637         kernel_cap_t new_cap;
638         int err, i;
639 
640         if (write && (!capable(CAP_SETPCAP) ||
641                       !capable(CAP_SYS_MODULE)))
642                 return -EPERM;
643 
644         /*
645          * convert from the global kernel_cap_t to the ulong array to print to
646          * userspace if this is a read.
647          */
648         spin_lock(&umh_sysctl_lock);
649         for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)  {
650                 if (table->data == CAP_BSET)
651                         cap_array[i] = usermodehelper_bset.cap[i];
652                 else if (table->data == CAP_PI)
653                         cap_array[i] = usermodehelper_inheritable.cap[i];
654                 else
655                         BUG();
656         }
657         spin_unlock(&umh_sysctl_lock);
658 
659         t = *table;
660         t.data = &cap_array;
661 
662         /*
663          * actually read or write and array of ulongs from userspace.  Remember
664          * these are least significant 32 bits first
665          */
666         err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
667         if (err < 0)
668                 return err;
669 
670         /*
671          * convert from the sysctl array of ulongs to the kernel_cap_t
672          * internal representation
673          */
674         for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
675                 new_cap.cap[i] = cap_array[i];
676 
677         /*
678          * Drop everything not in the new_cap (but don't add things)
679          */
680         if (write) {
681                 spin_lock(&umh_sysctl_lock);
682                 if (table->data == CAP_BSET)
683                         usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
684                 if (table->data == CAP_PI)
685                         usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
686                 spin_unlock(&umh_sysctl_lock);
687         }
688 
689         return 0;
690 }
691 
692 void __exit_umh(struct task_struct *tsk)
693 {
694         struct umh_info *info;
695         pid_t pid = tsk->pid;
696 
697         mutex_lock(&umh_list_lock);
698         list_for_each_entry(info, &umh_list, list) {
699                 if (info->pid == pid) {
700                         list_del(&info->list);
701                         mutex_unlock(&umh_list_lock);
702                         goto out;
703                 }
704         }
705         mutex_unlock(&umh_list_lock);
706         return;
707 out:
708         if (info->cleanup)
709                 info->cleanup(info);
710 }
711 
712 struct ctl_table usermodehelper_table[] = {
713         {
714                 .procname       = "bset",
715                 .data           = CAP_BSET,
716                 .maxlen         = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
717                 .mode           = 0600,
718                 .proc_handler   = proc_cap_handler,
719         },
720         {
721                 .procname       = "inheritable",
722                 .data           = CAP_PI,
723                 .maxlen         = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
724                 .mode           = 0600,
725                 .proc_handler   = proc_cap_handler,
726         },
727         { }
728 };
729 

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