Line data Source code
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 22 : static void free_modprobe_argv(struct subprocess_info *info)
66 : {
67 22 : kfree(info->argv[3]); /* check call_modprobe() */
68 22 : kfree(info->argv);
69 22 : }
70 :
71 22 : 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 22 : if (!argv)
83 : goto out;
84 :
85 22 : module_name = kstrdup(module_name, GFP_KERNEL);
86 22 : if (!module_name)
87 : goto free_argv;
88 :
89 22 : argv[0] = modprobe_path;
90 22 : argv[1] = "-q";
91 22 : argv[2] = "--";
92 22 : argv[3] = module_name; /* check free_modprobe_argv() */
93 22 : argv[4] = NULL;
94 :
95 22 : info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL,
96 : NULL, free_modprobe_argv, NULL);
97 22 : if (!info)
98 : goto free_module_name;
99 :
100 22 : return call_usermodehelper_exec(info, wait | UMH_KILLABLE);
101 :
102 : free_module_name:
103 0 : kfree(module_name);
104 : free_argv:
105 0 : 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 22 : 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 22 : WARN_ON_ONCE(wait && current_is_async());
142 :
143 22 : if (!modprobe_path[0])
144 : return 0;
145 :
146 22 : va_start(args, fmt);
147 22 : ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
148 22 : va_end(args);
149 22 : 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 22 : max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
169 : atomic_inc(&kmod_concurrent);
170 22 : if (atomic_read(&kmod_concurrent) > max_modprobes) {
171 : /* We may be blaming an innocent here, but unlikely */
172 0 : if (kmod_loop_msg < 5) {
173 0 : printk(KERN_ERR
174 : "request_module: runaway loop modprobe %s\n",
175 : module_name);
176 0 : kmod_loop_msg++;
177 : }
178 : atomic_dec(&kmod_concurrent);
179 0 : return -ENOMEM;
180 : }
181 :
182 22 : trace_module_request(module_name, wait, _RET_IP_);
183 :
184 22 : ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
185 :
186 : atomic_dec(&kmod_concurrent);
187 22 : return ret;
188 : }
189 : EXPORT_SYMBOL(__request_module);
190 : #endif /* CONFIG_MODULES */
191 :
192 22 : static void call_usermodehelper_freeinfo(struct subprocess_info *info)
193 : {
194 22 : if (info->cleanup)
195 22 : (*info->cleanup)(info);
196 22 : kfree(info);
197 22 : }
198 :
199 22 : static void umh_complete(struct subprocess_info *sub_info)
200 : {
201 44 : 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 22 : if (comp)
208 22 : complete(comp);
209 : else
210 0 : call_usermodehelper_freeinfo(sub_info);
211 22 : }
212 :
213 : /*
214 : * This is the task which runs the usermode application
215 : */
216 22 : 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(¤t->sighand->siglock);
223 22 : flush_signal_handlers(current, 1);
224 : spin_unlock_irq(¤t->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 22 : set_user_nice(current, 0);
234 :
235 : retval = -ENOMEM;
236 22 : new = prepare_kernel_cred(current);
237 22 : if (!new)
238 : goto out;
239 :
240 : spin_lock(&umh_sysctl_lock);
241 22 : new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
242 22 : new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
243 : new->cap_inheritable);
244 : spin_unlock(&umh_sysctl_lock);
245 :
246 22 : if (sub_info->init) {
247 0 : retval = sub_info->init(sub_info, new);
248 0 : if (retval) {
249 0 : abort_creds(new);
250 0 : goto out;
251 : }
252 : }
253 :
254 22 : commit_creds(new);
255 :
256 44 : retval = do_execve(getname_kernel(sub_info->path),
257 22 : (const char __user *const __user *)sub_info->argv,
258 22 : (const char __user *const __user *)sub_info->envp);
259 : out:
260 22 : sub_info->retval = retval;
261 : /* wait_for_helper() will call umh_complete if UHM_WAIT_PROC. */
262 22 : if (!(sub_info->wait & UMH_WAIT_PROC))
263 0 : umh_complete(sub_info);
264 22 : if (!retval)
265 22 : return 0;
266 0 : do_exit(0);
267 : }
268 :
269 : /* Keventd can't block, but this (a child) can. */
270 22 : 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 22 : kernel_sigaction(SIGCHLD, SIG_DFL);
277 22 : pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
278 22 : if (pid < 0) {
279 0 : sub_info->retval = pid;
280 : } else {
281 22 : 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 22 : 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 22 : if (ret)
299 22 : sub_info->retval = ret;
300 : }
301 :
302 22 : umh_complete(sub_info);
303 22 : do_exit(0);
304 : }
305 :
306 : /* This is run by khelper thread */
307 22 : 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 22 : if (sub_info->wait & UMH_WAIT_PROC)
314 22 : pid = kernel_thread(wait_for_helper, sub_info,
315 : CLONE_FS | CLONE_FILES | SIGCHLD);
316 : else
317 0 : pid = kernel_thread(____call_usermodehelper, sub_info,
318 : SIGCHLD);
319 :
320 22 : if (pid < 0) {
321 0 : sub_info->retval = pid;
322 0 : umh_complete(sub_info);
323 : }
324 22 : }
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 0 : int usermodehelper_read_trylock(void)
356 : {
357 0 : DEFINE_WAIT(wait);
358 : int ret = 0;
359 :
360 0 : down_read(&umhelper_sem);
361 : for (;;) {
362 0 : prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
363 : TASK_INTERRUPTIBLE);
364 0 : if (!usermodehelper_disabled)
365 : break;
366 :
367 0 : if (usermodehelper_disabled == UMH_DISABLED)
368 : ret = -EAGAIN;
369 :
370 0 : up_read(&umhelper_sem);
371 :
372 0 : if (ret)
373 : break;
374 :
375 0 : schedule();
376 : try_to_freeze();
377 :
378 0 : down_read(&umhelper_sem);
379 0 : }
380 0 : finish_wait(&usermodehelper_disabled_waitq, &wait);
381 0 : return ret;
382 : }
383 : EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
384 :
385 0 : long usermodehelper_read_lock_wait(long timeout)
386 : {
387 0 : DEFINE_WAIT(wait);
388 :
389 0 : if (timeout < 0)
390 : return -EINVAL;
391 :
392 0 : down_read(&umhelper_sem);
393 : for (;;) {
394 0 : prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
395 : TASK_UNINTERRUPTIBLE);
396 0 : if (!usermodehelper_disabled)
397 : break;
398 :
399 0 : up_read(&umhelper_sem);
400 :
401 0 : timeout = schedule_timeout(timeout);
402 0 : if (!timeout)
403 : break;
404 :
405 0 : down_read(&umhelper_sem);
406 0 : }
407 0 : finish_wait(&usermodehelper_disabled_waitq, &wait);
408 0 : return timeout;
409 : }
410 : EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
411 :
412 0 : void usermodehelper_read_unlock(void)
413 : {
414 0 : up_read(&umhelper_sem);
415 0 : }
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 1 : void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
426 : {
427 1 : down_write(&umhelper_sem);
428 1 : usermodehelper_disabled = depth;
429 1 : wake_up(&usermodehelper_disabled_waitq);
430 1 : up_write(&umhelper_sem);
431 1 : }
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 0 : int __usermodehelper_disable(enum umh_disable_depth depth)
440 : {
441 : long retval;
442 :
443 0 : if (!depth)
444 : return -EINVAL;
445 :
446 0 : down_write(&umhelper_sem);
447 0 : usermodehelper_disabled = depth;
448 0 : 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 0 : retval = wait_event_timeout(running_helpers_waitq,
457 : atomic_read(&running_helpers) == 0,
458 : RUNNING_HELPERS_TIMEOUT);
459 0 : if (retval)
460 : return 0;
461 :
462 0 : __usermodehelper_set_disable_depth(UMH_ENABLED);
463 0 : return -EAGAIN;
464 : }
465 :
466 : static void helper_lock(void)
467 : {
468 : atomic_inc(&running_helpers);
469 22 : smp_mb__after_atomic();
470 : }
471 :
472 22 : static void helper_unlock(void)
473 : {
474 22 : if (atomic_dec_and_test(&running_helpers))
475 21 : wake_up(&running_helpers_waitq);
476 22 : }
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 22 : 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 22 : if (!sub_info)
510 : goto out;
511 :
512 44 : INIT_WORK(&sub_info->work, __call_usermodehelper);
513 22 : sub_info->path = path;
514 22 : sub_info->argv = argv;
515 22 : sub_info->envp = envp;
516 :
517 22 : sub_info->cleanup = cleanup;
518 22 : sub_info->init = init;
519 22 : sub_info->data = data;
520 : out:
521 22 : 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 22 : int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
538 : {
539 22 : DECLARE_COMPLETION_ONSTACK(done);
540 : int retval = 0;
541 :
542 22 : if (!sub_info->path) {
543 0 : call_usermodehelper_freeinfo(sub_info);
544 0 : return -EINVAL;
545 : }
546 : helper_lock();
547 22 : 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 22 : sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done;
557 22 : sub_info->wait = wait;
558 :
559 22 : queue_work(khelper_wq, &sub_info->work);
560 22 : if (wait == UMH_NO_WAIT) /* task has freed sub_info */
561 : goto unlock;
562 :
563 22 : if (wait & UMH_KILLABLE) {
564 22 : retval = wait_for_completion_killable(&done);
565 22 : if (!retval)
566 : goto wait_done;
567 :
568 : /* umh_complete() will see NULL and free sub_info */
569 0 : if (xchg(&sub_info->complete, NULL))
570 : goto unlock;
571 : /* fallthrough, umh_complete() was already called */
572 : }
573 :
574 0 : wait_for_completion(&done);
575 : wait_done:
576 22 : retval = sub_info->retval;
577 : out:
578 22 : call_usermodehelper_freeinfo(sub_info);
579 : unlock:
580 22 : helper_unlock();
581 22 : 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 0 : int call_usermodehelper(char *path, char **argv, char **envp, int wait)
599 : {
600 : struct subprocess_info *info;
601 0 : gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
602 :
603 0 : info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
604 : NULL, NULL, NULL);
605 0 : if (info == NULL)
606 : return -ENOMEM;
607 :
608 0 : return call_usermodehelper_exec(info, wait);
609 : }
610 : EXPORT_SYMBOL(call_usermodehelper);
611 :
612 0 : 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 0 : if (write && (!capable(CAP_SETPCAP) ||
621 0 : !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 0 : for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) {
630 0 : if (table->data == CAP_BSET)
631 0 : cap_array[i] = usermodehelper_bset.cap[i];
632 0 : else if (table->data == CAP_PI)
633 0 : cap_array[i] = usermodehelper_inheritable.cap[i];
634 : else
635 : BUG();
636 : }
637 : spin_unlock(&umh_sysctl_lock);
638 :
639 0 : t = *table;
640 0 : 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 0 : err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
647 0 : 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 0 : for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
655 0 : 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 0 : if (write) {
662 0 : if (table->data == CAP_BSET)
663 0 : usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
664 0 : if (table->data == CAP_PI)
665 0 : 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 1 : void __init usermodehelper_init(void)
691 : {
692 1 : khelper_wq = create_singlethread_workqueue("khelper");
693 : BUG_ON(!khelper_wq);
694 1 : }
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