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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
48#define CAP_BSET (void *)1
49#define CAP_PI (void *)2
50
51static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
52static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
53static DEFINE_SPINLOCK(umh_sysctl_lock);
54static DECLARE_RWSEM(umhelper_sem);
55
56#ifdef CONFIG_MODULES
57
58
59
60
61char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
62
63static void free_modprobe_argv(struct subprocess_info *info)
64{
65 kfree(info->argv[3]);
66 kfree(info->argv);
67}
68
69static int call_modprobe(char *module_name, int wait)
70{
71 struct subprocess_info *info;
72 static char *envp[] = {
73 "HOME=/",
74 "TERM=linux",
75 "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
76 NULL
77 };
78
79 char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL);
80 if (!argv)
81 goto out;
82
83 module_name = kstrdup(module_name, GFP_KERNEL);
84 if (!module_name)
85 goto free_argv;
86
87 argv[0] = modprobe_path;
88 argv[1] = "-q";
89 argv[2] = "--";
90 argv[3] = module_name;
91 argv[4] = NULL;
92
93 info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL,
94 NULL, free_modprobe_argv, NULL);
95 if (!info)
96 goto free_module_name;
97
98 return call_usermodehelper_exec(info, wait | UMH_KILLABLE);
99
100free_module_name:
101 kfree(module_name);
102free_argv:
103 kfree(argv);
104out:
105 return -ENOMEM;
106}
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123
124int __request_module(bool wait, const char *fmt, ...)
125{
126 va_list args;
127 char module_name[MODULE_NAME_LEN];
128 unsigned int max_modprobes;
129 int ret;
130 static atomic_t kmod_concurrent = ATOMIC_INIT(0);
131#define MAX_KMOD_CONCURRENT 50
132 static int kmod_loop_msg;
133
134
135
136
137
138
139
140 WARN_ON_ONCE(wait && current_is_async());
141
142 if (!modprobe_path[0])
143 return 0;
144
145 va_start(args, fmt);
146 ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
147 va_end(args);
148 if (ret >= MODULE_NAME_LEN)
149 return -ENAMETOOLONG;
150
151 ret = security_kernel_module_request(module_name);
152 if (ret)
153 return ret;
154
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166
167 max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
168 atomic_inc(&kmod_concurrent);
169 if (atomic_read(&kmod_concurrent) > max_modprobes) {
170
171 if (kmod_loop_msg < 5) {
172 printk(KERN_ERR
173 "request_module: runaway loop modprobe %s\n",
174 module_name);
175 kmod_loop_msg++;
176 }
177 atomic_dec(&kmod_concurrent);
178 return -ENOMEM;
179 }
180
181 trace_module_request(module_name, wait, _RET_IP_);
182
183 ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
184
185 atomic_dec(&kmod_concurrent);
186 return ret;
187}
188EXPORT_SYMBOL(__request_module);
189#endif
190
191static void call_usermodehelper_freeinfo(struct subprocess_info *info)
192{
193 if (info->cleanup)
194 (*info->cleanup)(info);
195 kfree(info);
196}
197
198static void umh_complete(struct subprocess_info *sub_info)
199{
200 struct completion *comp = xchg(&sub_info->complete, NULL);
201
202
203
204
205
206 if (comp)
207 complete(comp);
208 else
209 call_usermodehelper_freeinfo(sub_info);
210}
211
212
213
214
215static int call_usermodehelper_exec_async(void *data)
216{
217 struct subprocess_info *sub_info = data;
218 struct cred *new;
219 int retval;
220
221 spin_lock_irq(¤t->sighand->siglock);
222 flush_signal_handlers(current, 1);
223 spin_unlock_irq(¤t->sighand->siglock);
224
225
226
227
228
229 set_user_nice(current, 0);
230
231 retval = -ENOMEM;
232 new = prepare_kernel_cred(current);
233 if (!new)
234 goto out;
235
236 spin_lock(&umh_sysctl_lock);
237 new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
238 new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
239 new->cap_inheritable);
240 spin_unlock(&umh_sysctl_lock);
241
242 if (sub_info->init) {
243 retval = sub_info->init(sub_info, new);
244 if (retval) {
245 abort_creds(new);
246 goto out;
247 }
248 }
249
250 commit_creds(new);
251
252 retval = do_execve(getname_kernel(sub_info->path),
253 (const char __user *const __user *)sub_info->argv,
254 (const char __user *const __user *)sub_info->envp);
255out:
256 sub_info->retval = retval;
257
258
259
260
261 if (!(sub_info->wait & UMH_WAIT_PROC))
262 umh_complete(sub_info);
263 if (!retval)
264 return 0;
265 do_exit(0);
266}
267
268
269static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
270{
271 pid_t pid;
272
273
274 kernel_sigaction(SIGCHLD, SIG_DFL);
275 pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD);
276 if (pid < 0) {
277 sub_info->retval = pid;
278 } else {
279 int ret = -ECHILD;
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290 sys_wait4(pid, (int __user *)&ret, 0, NULL);
291
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296
297 if (ret)
298 sub_info->retval = ret;
299 }
300
301
302 kernel_sigaction(SIGCHLD, SIG_IGN);
303
304 umh_complete(sub_info);
305}
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320
321static void call_usermodehelper_exec_work(struct work_struct *work)
322{
323 struct subprocess_info *sub_info =
324 container_of(work, struct subprocess_info, work);
325
326 if (sub_info->wait & UMH_WAIT_PROC) {
327 call_usermodehelper_exec_sync(sub_info);
328 } else {
329 pid_t pid;
330
331
332
333
334
335 pid = kernel_thread(call_usermodehelper_exec_async, sub_info,
336 CLONE_PARENT | SIGCHLD);
337 if (pid < 0) {
338 sub_info->retval = pid;
339 umh_complete(sub_info);
340 }
341 }
342}
343
344
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348
349
350static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
351
352
353static atomic_t running_helpers = ATOMIC_INIT(0);
354
355
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357
358
359static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
360
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363
364
365static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
366
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369
370
371#define RUNNING_HELPERS_TIMEOUT (5 * HZ)
372
373int usermodehelper_read_trylock(void)
374{
375 DEFINE_WAIT(wait);
376 int ret = 0;
377
378 down_read(&umhelper_sem);
379 for (;;) {
380 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
381 TASK_INTERRUPTIBLE);
382 if (!usermodehelper_disabled)
383 break;
384
385 if (usermodehelper_disabled == UMH_DISABLED)
386 ret = -EAGAIN;
387
388 up_read(&umhelper_sem);
389
390 if (ret)
391 break;
392
393 schedule();
394 try_to_freeze();
395
396 down_read(&umhelper_sem);
397 }
398 finish_wait(&usermodehelper_disabled_waitq, &wait);
399 return ret;
400}
401EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
402
403long usermodehelper_read_lock_wait(long timeout)
404{
405 DEFINE_WAIT(wait);
406
407 if (timeout < 0)
408 return -EINVAL;
409
410 down_read(&umhelper_sem);
411 for (;;) {
412 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
413 TASK_UNINTERRUPTIBLE);
414 if (!usermodehelper_disabled)
415 break;
416
417 up_read(&umhelper_sem);
418
419 timeout = schedule_timeout(timeout);
420 if (!timeout)
421 break;
422
423 down_read(&umhelper_sem);
424 }
425 finish_wait(&usermodehelper_disabled_waitq, &wait);
426 return timeout;
427}
428EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
429
430void usermodehelper_read_unlock(void)
431{
432 up_read(&umhelper_sem);
433}
434EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
435
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441
442
443void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
444{
445 down_write(&umhelper_sem);
446 usermodehelper_disabled = depth;
447 wake_up(&usermodehelper_disabled_waitq);
448 up_write(&umhelper_sem);
449}
450
451
452
453
454
455
456
457int __usermodehelper_disable(enum umh_disable_depth depth)
458{
459 long retval;
460
461 if (!depth)
462 return -EINVAL;
463
464 down_write(&umhelper_sem);
465 usermodehelper_disabled = depth;
466 up_write(&umhelper_sem);
467
468
469
470
471
472
473
474 retval = wait_event_timeout(running_helpers_waitq,
475 atomic_read(&running_helpers) == 0,
476 RUNNING_HELPERS_TIMEOUT);
477 if (retval)
478 return 0;
479
480 __usermodehelper_set_disable_depth(UMH_ENABLED);
481 return -EAGAIN;
482}
483
484static void helper_lock(void)
485{
486 atomic_inc(&running_helpers);
487 smp_mb__after_atomic();
488}
489
490static void helper_unlock(void)
491{
492 if (atomic_dec_and_test(&running_helpers))
493 wake_up(&running_helpers_waitq);
494}
495
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518
519struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
520 char **envp, gfp_t gfp_mask,
521 int (*init)(struct subprocess_info *info, struct cred *new),
522 void (*cleanup)(struct subprocess_info *info),
523 void *data)
524{
525 struct subprocess_info *sub_info;
526 sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
527 if (!sub_info)
528 goto out;
529
530 INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
531 sub_info->path = path;
532 sub_info->argv = argv;
533 sub_info->envp = envp;
534
535 sub_info->cleanup = cleanup;
536 sub_info->init = init;
537 sub_info->data = data;
538 out:
539 return sub_info;
540}
541EXPORT_SYMBOL(call_usermodehelper_setup);
542
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554
555int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
556{
557 DECLARE_COMPLETION_ONSTACK(done);
558 int retval = 0;
559
560 if (!sub_info->path) {
561 call_usermodehelper_freeinfo(sub_info);
562 return -EINVAL;
563 }
564 helper_lock();
565 if (usermodehelper_disabled) {
566 retval = -EBUSY;
567 goto out;
568 }
569
570
571
572
573
574 sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done;
575 sub_info->wait = wait;
576
577 queue_work(system_unbound_wq, &sub_info->work);
578 if (wait == UMH_NO_WAIT)
579 goto unlock;
580
581 if (wait & UMH_KILLABLE) {
582 retval = wait_for_completion_killable(&done);
583 if (!retval)
584 goto wait_done;
585
586
587 if (xchg(&sub_info->complete, NULL))
588 goto unlock;
589
590 }
591
592 wait_for_completion(&done);
593wait_done:
594 retval = sub_info->retval;
595out:
596 call_usermodehelper_freeinfo(sub_info);
597unlock:
598 helper_unlock();
599 return retval;
600}
601EXPORT_SYMBOL(call_usermodehelper_exec);
602
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615
616int call_usermodehelper(char *path, char **argv, char **envp, int wait)
617{
618 struct subprocess_info *info;
619 gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
620
621 info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
622 NULL, NULL, NULL);
623 if (info == NULL)
624 return -ENOMEM;
625
626 return call_usermodehelper_exec(info, wait);
627}
628EXPORT_SYMBOL(call_usermodehelper);
629
630static int proc_cap_handler(struct ctl_table *table, int write,
631 void __user *buffer, size_t *lenp, loff_t *ppos)
632{
633 struct ctl_table t;
634 unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
635 kernel_cap_t new_cap;
636 int err, i;
637
638 if (write && (!capable(CAP_SETPCAP) ||
639 !capable(CAP_SYS_MODULE)))
640 return -EPERM;
641
642
643
644
645
646 spin_lock(&umh_sysctl_lock);
647 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) {
648 if (table->data == CAP_BSET)
649 cap_array[i] = usermodehelper_bset.cap[i];
650 else if (table->data == CAP_PI)
651 cap_array[i] = usermodehelper_inheritable.cap[i];
652 else
653 BUG();
654 }
655 spin_unlock(&umh_sysctl_lock);
656
657 t = *table;
658 t.data = &cap_array;
659
660
661
662
663
664 err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
665 if (err < 0)
666 return err;
667
668
669
670
671
672 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
673 new_cap.cap[i] = cap_array[i];
674
675
676
677
678 spin_lock(&umh_sysctl_lock);
679 if (write) {
680 if (table->data == CAP_BSET)
681 usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
682 if (table->data == CAP_PI)
683 usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
684 }
685 spin_unlock(&umh_sysctl_lock);
686
687 return 0;
688}
689
690struct ctl_table usermodehelper_table[] = {
691 {
692 .procname = "bset",
693 .data = CAP_BSET,
694 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
695 .mode = 0600,
696 .proc_handler = proc_cap_handler,
697 },
698 {
699 .procname = "inheritable",
700 .data = CAP_PI,
701 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
702 .mode = 0600,
703 .proc_handler = proc_cap_handler,
704 },
705 { }
706};
707