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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/file.h>
29#include <linux/fdtable.h>
30#include <linux/workqueue.h>
31#include <linux/security.h>
32#include <linux/mount.h>
33#include <linux/kernel.h>
34#include <linux/init.h>
35#include <linux/resource.h>
36#include <linux/notifier.h>
37#include <linux/suspend.h>
38#include <asm/uaccess.h>
39
40#include <trace/events/module.h>
41
42extern int max_threads;
43
44static struct workqueue_struct *khelper_wq;
45
46#ifdef CONFIG_MODULES
47
48
49
50
51char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
52
53
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66
67
68int __request_module(bool wait, const char *fmt, ...)
69{
70 va_list args;
71 char module_name[MODULE_NAME_LEN];
72 unsigned int max_modprobes;
73 int ret;
74 char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
75 static char *envp[] = { "HOME=/",
76 "TERM=linux",
77 "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
78 NULL };
79 static atomic_t kmod_concurrent = ATOMIC_INIT(0);
80#define MAX_KMOD_CONCURRENT 50
81 static int kmod_loop_msg;
82
83 ret = security_kernel_module_request();
84 if (ret)
85 return ret;
86
87 va_start(args, fmt);
88 ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
89 va_end(args);
90 if (ret >= MODULE_NAME_LEN)
91 return -ENAMETOOLONG;
92
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103
104
105 max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
106 atomic_inc(&kmod_concurrent);
107 if (atomic_read(&kmod_concurrent) > max_modprobes) {
108
109 if (kmod_loop_msg++ < 5)
110 printk(KERN_ERR
111 "request_module: runaway loop modprobe %s\n",
112 module_name);
113 atomic_dec(&kmod_concurrent);
114 return -ENOMEM;
115 }
116
117 trace_module_request(module_name, wait, _RET_IP_);
118
119 ret = call_usermodehelper(modprobe_path, argv, envp,
120 wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
121 atomic_dec(&kmod_concurrent);
122 return ret;
123}
124EXPORT_SYMBOL(__request_module);
125#endif
126
127struct subprocess_info {
128 struct work_struct work;
129 struct completion *complete;
130 struct cred *cred;
131 char *path;
132 char **argv;
133 char **envp;
134 enum umh_wait wait;
135 int retval;
136 struct file *stdin;
137 void (*cleanup)(char **argv, char **envp);
138};
139
140
141
142
143static int ____call_usermodehelper(void *data)
144{
145 struct subprocess_info *sub_info = data;
146 int retval;
147
148 BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
149
150
151 spin_lock_irq(¤t->sighand->siglock);
152 flush_signal_handlers(current, 1);
153 sigemptyset(¤t->blocked);
154 recalc_sigpending();
155 spin_unlock_irq(¤t->sighand->siglock);
156
157
158 commit_creds(sub_info->cred);
159 sub_info->cred = NULL;
160
161
162 if (sub_info->stdin) {
163 struct files_struct *f = current->files;
164 struct fdtable *fdt;
165
166 sys_close(0);
167 fd_install(0, sub_info->stdin);
168 spin_lock(&f->file_lock);
169 fdt = files_fdtable(f);
170 FD_SET(0, fdt->open_fds);
171 FD_CLR(0, fdt->close_on_exec);
172 spin_unlock(&f->file_lock);
173
174
175 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){0, 0};
176 }
177
178
179 set_cpus_allowed_ptr(current, cpu_all_mask);
180
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182
183
184
185 set_user_nice(current, 0);
186
187 retval = kernel_execve(sub_info->path, sub_info->argv, sub_info->envp);
188
189
190 sub_info->retval = retval;
191 do_exit(0);
192}
193
194void call_usermodehelper_freeinfo(struct subprocess_info *info)
195{
196 if (info->cleanup)
197 (*info->cleanup)(info->argv, info->envp);
198 if (info->cred)
199 put_cred(info->cred);
200 kfree(info);
201}
202EXPORT_SYMBOL(call_usermodehelper_freeinfo);
203
204
205static int wait_for_helper(void *data)
206{
207 struct subprocess_info *sub_info = data;
208 pid_t pid;
209
210
211
212 allow_signal(SIGCHLD);
213
214 pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
215 if (pid < 0) {
216 sub_info->retval = pid;
217 } else {
218 int ret;
219
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229 sys_wait4(pid, (int __user *)&ret, 0, NULL);
230
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235
236 if (ret)
237 sub_info->retval = ret;
238 }
239
240 if (sub_info->wait == UMH_NO_WAIT)
241 call_usermodehelper_freeinfo(sub_info);
242 else
243 complete(sub_info->complete);
244 return 0;
245}
246
247
248static void __call_usermodehelper(struct work_struct *work)
249{
250 struct subprocess_info *sub_info =
251 container_of(work, struct subprocess_info, work);
252 pid_t pid;
253 enum umh_wait wait = sub_info->wait;
254
255 BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
256
257
258
259
260 if (wait == UMH_WAIT_PROC || wait == UMH_NO_WAIT)
261 pid = kernel_thread(wait_for_helper, sub_info,
262 CLONE_FS | CLONE_FILES | SIGCHLD);
263 else
264 pid = kernel_thread(____call_usermodehelper, sub_info,
265 CLONE_VFORK | SIGCHLD);
266
267 switch (wait) {
268 case UMH_NO_WAIT:
269 break;
270
271 case UMH_WAIT_PROC:
272 if (pid > 0)
273 break;
274 sub_info->retval = pid;
275
276
277 case UMH_WAIT_EXEC:
278 complete(sub_info->complete);
279 }
280}
281
282#ifdef CONFIG_PM_SLEEP
283
284
285
286
287
288static int usermodehelper_disabled;
289
290
291static atomic_t running_helpers = ATOMIC_INIT(0);
292
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296
297static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
298
299
300
301
302
303#define RUNNING_HELPERS_TIMEOUT (5 * HZ)
304
305
306
307
308int usermodehelper_disable(void)
309{
310 long retval;
311
312 usermodehelper_disabled = 1;
313 smp_mb();
314
315
316
317
318
319
320 retval = wait_event_timeout(running_helpers_waitq,
321 atomic_read(&running_helpers) == 0,
322 RUNNING_HELPERS_TIMEOUT);
323 if (retval)
324 return 0;
325
326 usermodehelper_disabled = 0;
327 return -EAGAIN;
328}
329
330
331
332
333void usermodehelper_enable(void)
334{
335 usermodehelper_disabled = 0;
336}
337
338static void helper_lock(void)
339{
340 atomic_inc(&running_helpers);
341 smp_mb__after_atomic_inc();
342}
343
344static void helper_unlock(void)
345{
346 if (atomic_dec_and_test(&running_helpers))
347 wake_up(&running_helpers_waitq);
348}
349#else
350#define usermodehelper_disabled 0
351
352static inline void helper_lock(void) {}
353static inline void helper_unlock(void) {}
354#endif
355
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366
367struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
368 char **envp, gfp_t gfp_mask)
369{
370 struct subprocess_info *sub_info;
371 sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
372 if (!sub_info)
373 goto out;
374
375 INIT_WORK(&sub_info->work, __call_usermodehelper);
376 sub_info->path = path;
377 sub_info->argv = argv;
378 sub_info->envp = envp;
379 sub_info->cred = prepare_usermodehelper_creds();
380 if (!sub_info->cred) {
381 kfree(sub_info);
382 return NULL;
383 }
384
385 out:
386 return sub_info;
387}
388EXPORT_SYMBOL(call_usermodehelper_setup);
389
390
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393
394
395void call_usermodehelper_setkeys(struct subprocess_info *info,
396 struct key *session_keyring)
397{
398#ifdef CONFIG_KEYS
399 struct thread_group_cred *tgcred = info->cred->tgcred;
400 key_put(tgcred->session_keyring);
401 tgcred->session_keyring = key_get(session_keyring);
402#else
403 BUG();
404#endif
405}
406EXPORT_SYMBOL(call_usermodehelper_setkeys);
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417
418void call_usermodehelper_setcleanup(struct subprocess_info *info,
419 void (*cleanup)(char **argv, char **envp))
420{
421 info->cleanup = cleanup;
422}
423EXPORT_SYMBOL(call_usermodehelper_setcleanup);
424
425
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431
432
433int call_usermodehelper_stdinpipe(struct subprocess_info *sub_info,
434 struct file **filp)
435{
436 struct file *f;
437
438 f = create_write_pipe(0);
439 if (IS_ERR(f))
440 return PTR_ERR(f);
441 *filp = f;
442
443 f = create_read_pipe(f, 0);
444 if (IS_ERR(f)) {
445 free_write_pipe(*filp);
446 return PTR_ERR(f);
447 }
448 sub_info->stdin = f;
449
450 return 0;
451}
452EXPORT_SYMBOL(call_usermodehelper_stdinpipe);
453
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464
465
466int call_usermodehelper_exec(struct subprocess_info *sub_info,
467 enum umh_wait wait)
468{
469 DECLARE_COMPLETION_ONSTACK(done);
470 int retval = 0;
471
472 BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
473 validate_creds(sub_info->cred);
474
475 helper_lock();
476 if (sub_info->path[0] == '\0')
477 goto out;
478
479 if (!khelper_wq || usermodehelper_disabled) {
480 retval = -EBUSY;
481 goto out;
482 }
483
484 sub_info->complete = &done;
485 sub_info->wait = wait;
486
487 queue_work(khelper_wq, &sub_info->work);
488 if (wait == UMH_NO_WAIT)
489 goto unlock;
490 wait_for_completion(&done);
491 retval = sub_info->retval;
492
493out:
494 call_usermodehelper_freeinfo(sub_info);
495unlock:
496 helper_unlock();
497 return retval;
498}
499EXPORT_SYMBOL(call_usermodehelper_exec);
500
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511
512int call_usermodehelper_pipe(char *path, char **argv, char **envp,
513 struct file **filp)
514{
515 struct subprocess_info *sub_info;
516 int ret;
517
518 sub_info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL);
519 if (sub_info == NULL)
520 return -ENOMEM;
521
522 ret = call_usermodehelper_stdinpipe(sub_info, filp);
523 if (ret < 0)
524 goto out;
525
526 return call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);
527
528 out:
529 call_usermodehelper_freeinfo(sub_info);
530 return ret;
531}
532EXPORT_SYMBOL(call_usermodehelper_pipe);
533
534void __init usermodehelper_init(void)
535{
536 khelper_wq = create_singlethread_workqueue("khelper");
537 BUG_ON(!khelper_wq);
538}
539