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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
51
52
53
54
55static const struct task_struct *kmod_thread_locker;
56
57#define CAP_BSET (void *)1
58#define CAP_PI (void *)2
59
60static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
61static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
62static DEFINE_SPINLOCK(umh_sysctl_lock);
63static DECLARE_RWSEM(umhelper_sem);
64
65#ifdef CONFIG_MODULES
66
67
68
69
70char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
71
72static void free_modprobe_argv(struct subprocess_info *info)
73{
74 kfree(info->argv[3]);
75 kfree(info->argv);
76}
77
78static 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;
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
109free_module_name:
110 kfree(module_name);
111free_argv:
112 kfree(argv);
113out:
114 return -ENOMEM;
115}
116
117
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124
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129
130
131
132int __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
140 static int kmod_loop_msg;
141
142
143
144
145
146
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
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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
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}
196EXPORT_SYMBOL(__request_module);
197#endif
198
199
200
201
202static 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(¤t->sighand->siglock);
209 flush_signal_handlers(current, 1);
210 spin_unlock_irq(¤t->sighand->siglock);
211
212
213 set_cpus_allowed_ptr(current, cpu_all_mask);
214
215
216
217
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(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
249fail:
250 sub_info->retval = retval;
251 do_exit(0);
252}
253
254static int call_helper(void *data)
255{
256
257 kmod_thread_locker = current;
258 return ____call_usermodehelper(data);
259}
260
261static void call_usermodehelper_freeinfo(struct subprocess_info *info)
262{
263 if (info->cleanup)
264 (*info->cleanup)(info);
265 kfree(info);
266}
267
268static void umh_complete(struct subprocess_info *sub_info)
269{
270 struct completion *comp = xchg(&sub_info->complete, NULL);
271
272
273
274
275 if (comp)
276 complete(comp);
277 else
278 call_usermodehelper_freeinfo(sub_info);
279}
280
281
282static int wait_for_helper(void *data)
283{
284 struct subprocess_info *sub_info = data;
285 pid_t pid;
286
287
288 spin_lock_irq(¤t->sighand->siglock);
289 current->sighand->action[SIGCHLD-1].sa.sa_handler = SIG_DFL;
290 spin_unlock_irq(¤t->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
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303
304
305
306 sys_wait4(pid, (int __user *)&ret, 0, NULL);
307
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311
312
313 if (ret)
314 sub_info->retval = ret;
315 }
316
317 umh_complete(sub_info);
318 do_exit(0);
319}
320
321
322static 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
330
331
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
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
351 case UMH_WAIT_EXEC:
352 if (pid < 0)
353 sub_info->retval = pid;
354 umh_complete(sub_info);
355 }
356}
357
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363
364static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
365
366
367static atomic_t running_helpers = ATOMIC_INIT(0);
368
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371
372
373static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
374
375
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377
378
379static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
380
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383
384
385#define RUNNING_HELPERS_TIMEOUT (5 * HZ)
386
387int 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}
415EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
416
417long 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}
442EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
443
444void usermodehelper_read_unlock(void)
445{
446 up_read(&umhelper_sem);
447}
448EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
449
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455
456
457void __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
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468
469
470
471int __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
484
485
486
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
498static void helper_lock(void)
499{
500 atomic_inc(&running_helpers);
501 smp_mb__after_atomic_inc();
502}
503
504static void helper_unlock(void)
505{
506 if (atomic_dec_and_test(&running_helpers))
507 wake_up(&running_helpers_waitq);
508}
509
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533struct 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}
555EXPORT_SYMBOL(call_usermodehelper_setup);
556
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568
569int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
570{
571 DECLARE_COMPLETION_ONSTACK(done);
572 int retval = 0;
573
574 helper_lock();
575 if (!khelper_wq || usermodehelper_disabled) {
576 retval = -EBUSY;
577 goto out;
578 }
579
580
581
582
583
584
585 if (wait != UMH_NO_WAIT && current == kmod_thread_locker) {
586 retval = -EBUSY;
587 goto out;
588 }
589
590 sub_info->complete = &done;
591 sub_info->wait = wait;
592
593 queue_work(khelper_wq, &sub_info->work);
594 if (wait == UMH_NO_WAIT)
595 goto unlock;
596
597 if (wait & UMH_KILLABLE) {
598 retval = wait_for_completion_killable(&done);
599 if (!retval)
600 goto wait_done;
601
602
603 if (xchg(&sub_info->complete, NULL))
604 goto unlock;
605
606 }
607
608 wait_for_completion(&done);
609wait_done:
610 retval = sub_info->retval;
611out:
612 call_usermodehelper_freeinfo(sub_info);
613unlock:
614 helper_unlock();
615 return retval;
616}
617EXPORT_SYMBOL(call_usermodehelper_exec);
618
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631
632int call_usermodehelper(char *path, char **argv, char **envp, int wait)
633{
634 struct subprocess_info *info;
635 gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
636
637 info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
638 NULL, NULL, NULL);
639 if (info == NULL)
640 return -ENOMEM;
641
642 return call_usermodehelper_exec(info, wait);
643}
644EXPORT_SYMBOL(call_usermodehelper);
645
646static int proc_cap_handler(struct ctl_table *table, int write,
647 void __user *buffer, size_t *lenp, loff_t *ppos)
648{
649 struct ctl_table t;
650 unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
651 kernel_cap_t new_cap;
652 int err, i;
653
654 if (write && (!capable(CAP_SETPCAP) ||
655 !capable(CAP_SYS_MODULE)))
656 return -EPERM;
657
658
659
660
661
662 spin_lock(&umh_sysctl_lock);
663 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) {
664 if (table->data == CAP_BSET)
665 cap_array[i] = usermodehelper_bset.cap[i];
666 else if (table->data == CAP_PI)
667 cap_array[i] = usermodehelper_inheritable.cap[i];
668 else
669 BUG();
670 }
671 spin_unlock(&umh_sysctl_lock);
672
673 t = *table;
674 t.data = &cap_array;
675
676
677
678
679
680 err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
681 if (err < 0)
682 return err;
683
684
685
686
687
688 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
689 new_cap.cap[i] = cap_array[i];
690
691
692
693
694 spin_lock(&umh_sysctl_lock);
695 if (write) {
696 if (table->data == CAP_BSET)
697 usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
698 if (table->data == CAP_PI)
699 usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
700 }
701 spin_unlock(&umh_sysctl_lock);
702
703 return 0;
704}
705
706struct ctl_table usermodehelper_table[] = {
707 {
708 .procname = "bset",
709 .data = CAP_BSET,
710 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
711 .mode = 0600,
712 .proc_handler = proc_cap_handler,
713 },
714 {
715 .procname = "inheritable",
716 .data = CAP_PI,
717 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
718 .mode = 0600,
719 .proc_handler = proc_cap_handler,
720 },
721 { }
722};
723
724void __init usermodehelper_init(void)
725{
726 khelper_wq = create_singlethread_workqueue("khelper");
727 BUG_ON(!khelper_wq);
728}
729