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Commit | Line | Data |
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23558693 LR |
1 | /* |
2 | * umh - the kernel usermode helper | |
3 | */ | |
4 | #include <linux/module.h> | |
5 | #include <linux/sched.h> | |
6 | #include <linux/sched/task.h> | |
7 | #include <linux/binfmts.h> | |
8 | #include <linux/syscalls.h> | |
9 | #include <linux/unistd.h> | |
10 | #include <linux/kmod.h> | |
11 | #include <linux/slab.h> | |
12 | #include <linux/completion.h> | |
13 | #include <linux/cred.h> | |
14 | #include <linux/file.h> | |
15 | #include <linux/fdtable.h> | |
16 | #include <linux/workqueue.h> | |
17 | #include <linux/security.h> | |
18 | #include <linux/mount.h> | |
19 | #include <linux/kernel.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/resource.h> | |
22 | #include <linux/notifier.h> | |
23 | #include <linux/suspend.h> | |
24 | #include <linux/rwsem.h> | |
25 | #include <linux/ptrace.h> | |
26 | #include <linux/async.h> | |
27 | #include <linux/uaccess.h> | |
449325b5 AS |
28 | #include <linux/shmem_fs.h> |
29 | #include <linux/pipe_fs_i.h> | |
23558693 LR |
30 | |
31 | #include <trace/events/module.h> | |
32 | ||
33 | #define CAP_BSET (void *)1 | |
34 | #define CAP_PI (void *)2 | |
35 | ||
36 | static kernel_cap_t usermodehelper_bset = CAP_FULL_SET; | |
37 | static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET; | |
38 | static DEFINE_SPINLOCK(umh_sysctl_lock); | |
39 | static DECLARE_RWSEM(umhelper_sem); | |
40 | ||
41 | static void call_usermodehelper_freeinfo(struct subprocess_info *info) | |
42 | { | |
43 | if (info->cleanup) | |
44 | (*info->cleanup)(info); | |
45 | kfree(info); | |
46 | } | |
47 | ||
48 | static void umh_complete(struct subprocess_info *sub_info) | |
49 | { | |
50 | struct completion *comp = xchg(&sub_info->complete, NULL); | |
51 | /* | |
52 | * See call_usermodehelper_exec(). If xchg() returns NULL | |
53 | * we own sub_info, the UMH_KILLABLE caller has gone away | |
54 | * or the caller used UMH_NO_WAIT. | |
55 | */ | |
56 | if (comp) | |
57 | complete(comp); | |
58 | else | |
59 | call_usermodehelper_freeinfo(sub_info); | |
60 | } | |
61 | ||
62 | /* | |
63 | * This is the task which runs the usermode application | |
64 | */ | |
65 | static int call_usermodehelper_exec_async(void *data) | |
66 | { | |
67 | struct subprocess_info *sub_info = data; | |
68 | struct cred *new; | |
69 | int retval; | |
70 | ||
71 | spin_lock_irq(¤t->sighand->siglock); | |
72 | flush_signal_handlers(current, 1); | |
73 | spin_unlock_irq(¤t->sighand->siglock); | |
74 | ||
75 | /* | |
76 | * Our parent (unbound workqueue) runs with elevated scheduling | |
77 | * priority. Avoid propagating that into the userspace child. | |
78 | */ | |
79 | set_user_nice(current, 0); | |
80 | ||
81 | retval = -ENOMEM; | |
82 | new = prepare_kernel_cred(current); | |
83 | if (!new) | |
84 | goto out; | |
85 | ||
86 | spin_lock(&umh_sysctl_lock); | |
87 | new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset); | |
88 | new->cap_inheritable = cap_intersect(usermodehelper_inheritable, | |
89 | new->cap_inheritable); | |
90 | spin_unlock(&umh_sysctl_lock); | |
91 | ||
92 | if (sub_info->init) { | |
93 | retval = sub_info->init(sub_info, new); | |
94 | if (retval) { | |
95 | abort_creds(new); | |
96 | goto out; | |
97 | } | |
98 | } | |
99 | ||
100 | commit_creds(new); | |
101 | ||
bf956be5 | 102 | sub_info->pid = task_pid_nr(current); |
449325b5 AS |
103 | if (sub_info->file) |
104 | retval = do_execve_file(sub_info->file, | |
105 | sub_info->argv, sub_info->envp); | |
106 | else | |
107 | retval = do_execve(getname_kernel(sub_info->path), | |
108 | (const char __user *const __user *)sub_info->argv, | |
109 | (const char __user *const __user *)sub_info->envp); | |
23558693 LR |
110 | out: |
111 | sub_info->retval = retval; | |
112 | /* | |
113 | * call_usermodehelper_exec_sync() will call umh_complete | |
114 | * if UHM_WAIT_PROC. | |
115 | */ | |
116 | if (!(sub_info->wait & UMH_WAIT_PROC)) | |
117 | umh_complete(sub_info); | |
118 | if (!retval) | |
119 | return 0; | |
120 | do_exit(0); | |
121 | } | |
122 | ||
123 | /* Handles UMH_WAIT_PROC. */ | |
124 | static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info) | |
125 | { | |
126 | pid_t pid; | |
127 | ||
d300b610 | 128 | /* If SIGCLD is ignored kernel_wait4 won't populate the status. */ |
23558693 LR |
129 | kernel_sigaction(SIGCHLD, SIG_DFL); |
130 | pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD); | |
131 | if (pid < 0) { | |
132 | sub_info->retval = pid; | |
133 | } else { | |
134 | int ret = -ECHILD; | |
135 | /* | |
136 | * Normally it is bogus to call wait4() from in-kernel because | |
137 | * wait4() wants to write the exit code to a userspace address. | |
138 | * But call_usermodehelper_exec_sync() always runs as kernel | |
139 | * thread (workqueue) and put_user() to a kernel address works | |
140 | * OK for kernel threads, due to their having an mm_segment_t | |
141 | * which spans the entire address space. | |
142 | * | |
143 | * Thus the __user pointer cast is valid here. | |
144 | */ | |
d300b610 | 145 | kernel_wait4(pid, (int __user *)&ret, 0, NULL); |
23558693 LR |
146 | |
147 | /* | |
148 | * If ret is 0, either call_usermodehelper_exec_async failed and | |
149 | * the real error code is already in sub_info->retval or | |
150 | * sub_info->retval is 0 anyway, so don't mess with it then. | |
151 | */ | |
152 | if (ret) | |
153 | sub_info->retval = ret; | |
154 | } | |
155 | ||
156 | /* Restore default kernel sig handler */ | |
157 | kernel_sigaction(SIGCHLD, SIG_IGN); | |
158 | ||
159 | umh_complete(sub_info); | |
160 | } | |
161 | ||
162 | /* | |
163 | * We need to create the usermodehelper kernel thread from a task that is affine | |
164 | * to an optimized set of CPUs (or nohz housekeeping ones) such that they | |
165 | * inherit a widest affinity irrespective of call_usermodehelper() callers with | |
166 | * possibly reduced affinity (eg: per-cpu workqueues). We don't want | |
167 | * usermodehelper targets to contend a busy CPU. | |
168 | * | |
169 | * Unbound workqueues provide such wide affinity and allow to block on | |
170 | * UMH_WAIT_PROC requests without blocking pending request (up to some limit). | |
171 | * | |
172 | * Besides, workqueues provide the privilege level that caller might not have | |
173 | * to perform the usermodehelper request. | |
174 | * | |
175 | */ | |
176 | static void call_usermodehelper_exec_work(struct work_struct *work) | |
177 | { | |
178 | struct subprocess_info *sub_info = | |
179 | container_of(work, struct subprocess_info, work); | |
180 | ||
181 | if (sub_info->wait & UMH_WAIT_PROC) { | |
182 | call_usermodehelper_exec_sync(sub_info); | |
183 | } else { | |
184 | pid_t pid; | |
185 | /* | |
186 | * Use CLONE_PARENT to reparent it to kthreadd; we do not | |
187 | * want to pollute current->children, and we need a parent | |
188 | * that always ignores SIGCHLD to ensure auto-reaping. | |
189 | */ | |
190 | pid = kernel_thread(call_usermodehelper_exec_async, sub_info, | |
191 | CLONE_PARENT | SIGCHLD); | |
192 | if (pid < 0) { | |
193 | sub_info->retval = pid; | |
194 | umh_complete(sub_info); | |
195 | } | |
196 | } | |
197 | } | |
198 | ||
199 | /* | |
200 | * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY | |
201 | * (used for preventing user land processes from being created after the user | |
202 | * land has been frozen during a system-wide hibernation or suspend operation). | |
203 | * Should always be manipulated under umhelper_sem acquired for write. | |
204 | */ | |
205 | static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED; | |
206 | ||
207 | /* Number of helpers running */ | |
208 | static atomic_t running_helpers = ATOMIC_INIT(0); | |
209 | ||
210 | /* | |
211 | * Wait queue head used by usermodehelper_disable() to wait for all running | |
212 | * helpers to finish. | |
213 | */ | |
214 | static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); | |
215 | ||
216 | /* | |
217 | * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled | |
218 | * to become 'false'. | |
219 | */ | |
220 | static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq); | |
221 | ||
222 | /* | |
223 | * Time to wait for running_helpers to become zero before the setting of | |
224 | * usermodehelper_disabled in usermodehelper_disable() fails | |
225 | */ | |
226 | #define RUNNING_HELPERS_TIMEOUT (5 * HZ) | |
227 | ||
228 | int usermodehelper_read_trylock(void) | |
229 | { | |
230 | DEFINE_WAIT(wait); | |
231 | int ret = 0; | |
232 | ||
233 | down_read(&umhelper_sem); | |
234 | for (;;) { | |
235 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
236 | TASK_INTERRUPTIBLE); | |
237 | if (!usermodehelper_disabled) | |
238 | break; | |
239 | ||
240 | if (usermodehelper_disabled == UMH_DISABLED) | |
241 | ret = -EAGAIN; | |
242 | ||
243 | up_read(&umhelper_sem); | |
244 | ||
245 | if (ret) | |
246 | break; | |
247 | ||
248 | schedule(); | |
249 | try_to_freeze(); | |
250 | ||
251 | down_read(&umhelper_sem); | |
252 | } | |
253 | finish_wait(&usermodehelper_disabled_waitq, &wait); | |
254 | return ret; | |
255 | } | |
256 | EXPORT_SYMBOL_GPL(usermodehelper_read_trylock); | |
257 | ||
258 | long usermodehelper_read_lock_wait(long timeout) | |
259 | { | |
260 | DEFINE_WAIT(wait); | |
261 | ||
262 | if (timeout < 0) | |
263 | return -EINVAL; | |
264 | ||
265 | down_read(&umhelper_sem); | |
266 | for (;;) { | |
267 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
268 | TASK_UNINTERRUPTIBLE); | |
269 | if (!usermodehelper_disabled) | |
270 | break; | |
271 | ||
272 | up_read(&umhelper_sem); | |
273 | ||
274 | timeout = schedule_timeout(timeout); | |
275 | if (!timeout) | |
276 | break; | |
277 | ||
278 | down_read(&umhelper_sem); | |
279 | } | |
280 | finish_wait(&usermodehelper_disabled_waitq, &wait); | |
281 | return timeout; | |
282 | } | |
283 | EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait); | |
284 | ||
285 | void usermodehelper_read_unlock(void) | |
286 | { | |
287 | up_read(&umhelper_sem); | |
288 | } | |
289 | EXPORT_SYMBOL_GPL(usermodehelper_read_unlock); | |
290 | ||
291 | /** | |
292 | * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled. | |
293 | * @depth: New value to assign to usermodehelper_disabled. | |
294 | * | |
295 | * Change the value of usermodehelper_disabled (under umhelper_sem locked for | |
296 | * writing) and wakeup tasks waiting for it to change. | |
297 | */ | |
298 | void __usermodehelper_set_disable_depth(enum umh_disable_depth depth) | |
299 | { | |
300 | down_write(&umhelper_sem); | |
301 | usermodehelper_disabled = depth; | |
302 | wake_up(&usermodehelper_disabled_waitq); | |
303 | up_write(&umhelper_sem); | |
304 | } | |
305 | ||
306 | /** | |
307 | * __usermodehelper_disable - Prevent new helpers from being started. | |
308 | * @depth: New value to assign to usermodehelper_disabled. | |
309 | * | |
310 | * Set usermodehelper_disabled to @depth and wait for running helpers to exit. | |
311 | */ | |
312 | int __usermodehelper_disable(enum umh_disable_depth depth) | |
313 | { | |
314 | long retval; | |
315 | ||
316 | if (!depth) | |
317 | return -EINVAL; | |
318 | ||
319 | down_write(&umhelper_sem); | |
320 | usermodehelper_disabled = depth; | |
321 | up_write(&umhelper_sem); | |
322 | ||
323 | /* | |
324 | * From now on call_usermodehelper_exec() won't start any new | |
325 | * helpers, so it is sufficient if running_helpers turns out to | |
326 | * be zero at one point (it may be increased later, but that | |
327 | * doesn't matter). | |
328 | */ | |
329 | retval = wait_event_timeout(running_helpers_waitq, | |
330 | atomic_read(&running_helpers) == 0, | |
331 | RUNNING_HELPERS_TIMEOUT); | |
332 | if (retval) | |
333 | return 0; | |
334 | ||
335 | __usermodehelper_set_disable_depth(UMH_ENABLED); | |
336 | return -EAGAIN; | |
337 | } | |
338 | ||
339 | static void helper_lock(void) | |
340 | { | |
341 | atomic_inc(&running_helpers); | |
342 | smp_mb__after_atomic(); | |
343 | } | |
344 | ||
345 | static void helper_unlock(void) | |
346 | { | |
347 | if (atomic_dec_and_test(&running_helpers)) | |
348 | wake_up(&running_helpers_waitq); | |
349 | } | |
350 | ||
351 | /** | |
352 | * call_usermodehelper_setup - prepare to call a usermode helper | |
353 | * @path: path to usermode executable | |
354 | * @argv: arg vector for process | |
355 | * @envp: environment for process | |
356 | * @gfp_mask: gfp mask for memory allocation | |
357 | * @cleanup: a cleanup function | |
358 | * @init: an init function | |
359 | * @data: arbitrary context sensitive data | |
360 | * | |
361 | * Returns either %NULL on allocation failure, or a subprocess_info | |
362 | * structure. This should be passed to call_usermodehelper_exec to | |
363 | * exec the process and free the structure. | |
364 | * | |
365 | * The init function is used to customize the helper process prior to | |
366 | * exec. A non-zero return code causes the process to error out, exit, | |
367 | * and return the failure to the calling process | |
368 | * | |
369 | * The cleanup function is just before ethe subprocess_info is about to | |
370 | * be freed. This can be used for freeing the argv and envp. The | |
371 | * Function must be runnable in either a process context or the | |
372 | * context in which call_usermodehelper_exec is called. | |
373 | */ | |
374 | struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv, | |
375 | char **envp, gfp_t gfp_mask, | |
376 | int (*init)(struct subprocess_info *info, struct cred *new), | |
377 | void (*cleanup)(struct subprocess_info *info), | |
378 | void *data) | |
379 | { | |
380 | struct subprocess_info *sub_info; | |
381 | sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask); | |
382 | if (!sub_info) | |
383 | goto out; | |
384 | ||
385 | INIT_WORK(&sub_info->work, call_usermodehelper_exec_work); | |
386 | ||
387 | #ifdef CONFIG_STATIC_USERMODEHELPER | |
388 | sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH; | |
389 | #else | |
390 | sub_info->path = path; | |
391 | #endif | |
392 | sub_info->argv = argv; | |
393 | sub_info->envp = envp; | |
394 | ||
395 | sub_info->cleanup = cleanup; | |
396 | sub_info->init = init; | |
397 | sub_info->data = data; | |
398 | out: | |
399 | return sub_info; | |
400 | } | |
401 | EXPORT_SYMBOL(call_usermodehelper_setup); | |
402 | ||
449325b5 AS |
403 | struct subprocess_info *call_usermodehelper_setup_file(struct file *file, |
404 | int (*init)(struct subprocess_info *info, struct cred *new), | |
405 | void (*cleanup)(struct subprocess_info *info), void *data) | |
406 | { | |
407 | struct subprocess_info *sub_info; | |
876dcf2f OB |
408 | struct umh_info *info = data; |
409 | const char *cmdline = (info->cmdline) ? info->cmdline : "usermodehelper"; | |
449325b5 AS |
410 | |
411 | sub_info = kzalloc(sizeof(struct subprocess_info), GFP_KERNEL); | |
412 | if (!sub_info) | |
413 | return NULL; | |
414 | ||
876dcf2f OB |
415 | sub_info->argv = argv_split(GFP_KERNEL, cmdline, NULL); |
416 | if (!sub_info->argv) { | |
417 | kfree(sub_info); | |
418 | return NULL; | |
419 | } | |
420 | ||
449325b5 AS |
421 | INIT_WORK(&sub_info->work, call_usermodehelper_exec_work); |
422 | sub_info->path = "none"; | |
423 | sub_info->file = file; | |
424 | sub_info->init = init; | |
425 | sub_info->cleanup = cleanup; | |
426 | sub_info->data = data; | |
427 | return sub_info; | |
428 | } | |
429 | ||
430 | static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) | |
431 | { | |
432 | struct umh_info *umh_info = info->data; | |
433 | struct file *from_umh[2]; | |
434 | struct file *to_umh[2]; | |
435 | int err; | |
436 | ||
437 | /* create pipe to send data to umh */ | |
438 | err = create_pipe_files(to_umh, 0); | |
439 | if (err) | |
440 | return err; | |
441 | err = replace_fd(0, to_umh[0], 0); | |
442 | fput(to_umh[0]); | |
443 | if (err < 0) { | |
444 | fput(to_umh[1]); | |
445 | return err; | |
446 | } | |
447 | ||
448 | /* create pipe to receive data from umh */ | |
449 | err = create_pipe_files(from_umh, 0); | |
450 | if (err) { | |
451 | fput(to_umh[1]); | |
452 | replace_fd(0, NULL, 0); | |
453 | return err; | |
454 | } | |
455 | err = replace_fd(1, from_umh[1], 0); | |
456 | fput(from_umh[1]); | |
457 | if (err < 0) { | |
458 | fput(to_umh[1]); | |
459 | replace_fd(0, NULL, 0); | |
460 | fput(from_umh[0]); | |
461 | return err; | |
462 | } | |
463 | ||
464 | umh_info->pipe_to_umh = to_umh[1]; | |
465 | umh_info->pipe_from_umh = from_umh[0]; | |
466 | return 0; | |
467 | } | |
468 | ||
876dcf2f | 469 | static void umh_clean_and_save_pid(struct subprocess_info *info) |
449325b5 AS |
470 | { |
471 | struct umh_info *umh_info = info->data; | |
472 | ||
876dcf2f | 473 | argv_free(info->argv); |
449325b5 AS |
474 | umh_info->pid = info->pid; |
475 | } | |
476 | ||
477 | /** | |
478 | * fork_usermode_blob - fork a blob of bytes as a usermode process | |
479 | * @data: a blob of bytes that can be do_execv-ed as a file | |
480 | * @len: length of the blob | |
481 | * @info: information about usermode process (shouldn't be NULL) | |
482 | * | |
876dcf2f OB |
483 | * If info->cmdline is set it will be used as command line for the |
484 | * user process, else "usermodehelper" is used. | |
485 | * | |
449325b5 AS |
486 | * Returns either negative error or zero which indicates success |
487 | * in executing a blob of bytes as a usermode process. In such | |
488 | * case 'struct umh_info *info' is populated with two pipes | |
489 | * and a pid of the process. The caller is responsible for health | |
490 | * check of the user process, killing it via pid, and closing the | |
491 | * pipes when user process is no longer needed. | |
492 | */ | |
493 | int fork_usermode_blob(void *data, size_t len, struct umh_info *info) | |
494 | { | |
495 | struct subprocess_info *sub_info; | |
496 | struct file *file; | |
497 | ssize_t written; | |
498 | loff_t pos = 0; | |
499 | int err; | |
500 | ||
501 | file = shmem_kernel_file_setup("", len, 0); | |
502 | if (IS_ERR(file)) | |
503 | return PTR_ERR(file); | |
504 | ||
505 | written = kernel_write(file, data, len, &pos); | |
506 | if (written != len) { | |
507 | err = written; | |
508 | if (err >= 0) | |
509 | err = -ENOMEM; | |
510 | goto out; | |
511 | } | |
512 | ||
513 | err = -ENOMEM; | |
514 | sub_info = call_usermodehelper_setup_file(file, umh_pipe_setup, | |
876dcf2f | 515 | umh_clean_and_save_pid, info); |
449325b5 AS |
516 | if (!sub_info) |
517 | goto out; | |
518 | ||
519 | err = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC); | |
520 | out: | |
521 | fput(file); | |
522 | return err; | |
523 | } | |
524 | EXPORT_SYMBOL_GPL(fork_usermode_blob); | |
525 | ||
23558693 LR |
526 | /** |
527 | * call_usermodehelper_exec - start a usermode application | |
528 | * @sub_info: information about the subprocessa | |
529 | * @wait: wait for the application to finish and return status. | |
530 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back | |
531 | * when the program couldn't be exec'ed. This makes it safe to call | |
532 | * from interrupt context. | |
533 | * | |
534 | * Runs a user-space application. The application is started | |
535 | * asynchronously if wait is not set, and runs as a child of system workqueues. | |
536 | * (ie. it runs with full root capabilities and optimized affinity). | |
537 | */ | |
538 | int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) | |
539 | { | |
540 | DECLARE_COMPLETION_ONSTACK(done); | |
541 | int retval = 0; | |
542 | ||
543 | if (!sub_info->path) { | |
544 | call_usermodehelper_freeinfo(sub_info); | |
545 | return -EINVAL; | |
546 | } | |
547 | helper_lock(); | |
548 | if (usermodehelper_disabled) { | |
549 | retval = -EBUSY; | |
550 | goto out; | |
551 | } | |
552 | ||
553 | /* | |
554 | * If there is no binary for us to call, then just return and get out of | |
555 | * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and | |
556 | * disable all call_usermodehelper() calls. | |
557 | */ | |
558 | if (strlen(sub_info->path) == 0) | |
559 | goto out; | |
560 | ||
561 | /* | |
562 | * Set the completion pointer only if there is a waiter. | |
563 | * This makes it possible to use umh_complete to free | |
564 | * the data structure in case of UMH_NO_WAIT. | |
565 | */ | |
566 | sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done; | |
567 | sub_info->wait = wait; | |
568 | ||
569 | queue_work(system_unbound_wq, &sub_info->work); | |
570 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ | |
571 | goto unlock; | |
572 | ||
573 | if (wait & UMH_KILLABLE) { | |
574 | retval = wait_for_completion_killable(&done); | |
575 | if (!retval) | |
576 | goto wait_done; | |
577 | ||
578 | /* umh_complete() will see NULL and free sub_info */ | |
579 | if (xchg(&sub_info->complete, NULL)) | |
580 | goto unlock; | |
581 | /* fallthrough, umh_complete() was already called */ | |
582 | } | |
583 | ||
584 | wait_for_completion(&done); | |
585 | wait_done: | |
586 | retval = sub_info->retval; | |
587 | out: | |
588 | call_usermodehelper_freeinfo(sub_info); | |
589 | unlock: | |
590 | helper_unlock(); | |
591 | return retval; | |
592 | } | |
593 | EXPORT_SYMBOL(call_usermodehelper_exec); | |
594 | ||
595 | /** | |
596 | * call_usermodehelper() - prepare and start a usermode application | |
597 | * @path: path to usermode executable | |
598 | * @argv: arg vector for process | |
599 | * @envp: environment for process | |
600 | * @wait: wait for the application to finish and return status. | |
601 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back | |
602 | * when the program couldn't be exec'ed. This makes it safe to call | |
603 | * from interrupt context. | |
604 | * | |
605 | * This function is the equivalent to use call_usermodehelper_setup() and | |
606 | * call_usermodehelper_exec(). | |
607 | */ | |
608 | int call_usermodehelper(const char *path, char **argv, char **envp, int wait) | |
609 | { | |
610 | struct subprocess_info *info; | |
611 | gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL; | |
612 | ||
613 | info = call_usermodehelper_setup(path, argv, envp, gfp_mask, | |
614 | NULL, NULL, NULL); | |
615 | if (info == NULL) | |
616 | return -ENOMEM; | |
617 | ||
618 | return call_usermodehelper_exec(info, wait); | |
619 | } | |
620 | EXPORT_SYMBOL(call_usermodehelper); | |
621 | ||
622 | static int proc_cap_handler(struct ctl_table *table, int write, | |
623 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
624 | { | |
625 | struct ctl_table t; | |
626 | unsigned long cap_array[_KERNEL_CAPABILITY_U32S]; | |
627 | kernel_cap_t new_cap; | |
628 | int err, i; | |
629 | ||
630 | if (write && (!capable(CAP_SETPCAP) || | |
631 | !capable(CAP_SYS_MODULE))) | |
632 | return -EPERM; | |
633 | ||
634 | /* | |
635 | * convert from the global kernel_cap_t to the ulong array to print to | |
636 | * userspace if this is a read. | |
637 | */ | |
638 | spin_lock(&umh_sysctl_lock); | |
639 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) { | |
640 | if (table->data == CAP_BSET) | |
641 | cap_array[i] = usermodehelper_bset.cap[i]; | |
642 | else if (table->data == CAP_PI) | |
643 | cap_array[i] = usermodehelper_inheritable.cap[i]; | |
644 | else | |
645 | BUG(); | |
646 | } | |
647 | spin_unlock(&umh_sysctl_lock); | |
648 | ||
649 | t = *table; | |
650 | t.data = &cap_array; | |
651 | ||
652 | /* | |
653 | * actually read or write and array of ulongs from userspace. Remember | |
654 | * these are least significant 32 bits first | |
655 | */ | |
656 | err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); | |
657 | if (err < 0) | |
658 | return err; | |
659 | ||
660 | /* | |
661 | * convert from the sysctl array of ulongs to the kernel_cap_t | |
662 | * internal representation | |
663 | */ | |
664 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) | |
665 | new_cap.cap[i] = cap_array[i]; | |
666 | ||
667 | /* | |
668 | * Drop everything not in the new_cap (but don't add things) | |
669 | */ | |
23558693 | 670 | if (write) { |
8c703d66 | 671 | spin_lock(&umh_sysctl_lock); |
23558693 LR |
672 | if (table->data == CAP_BSET) |
673 | usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap); | |
674 | if (table->data == CAP_PI) | |
675 | usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap); | |
8c703d66 | 676 | spin_unlock(&umh_sysctl_lock); |
23558693 | 677 | } |
23558693 LR |
678 | |
679 | return 0; | |
680 | } | |
681 | ||
682 | struct ctl_table usermodehelper_table[] = { | |
683 | { | |
684 | .procname = "bset", | |
685 | .data = CAP_BSET, | |
686 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
687 | .mode = 0600, | |
688 | .proc_handler = proc_cap_handler, | |
689 | }, | |
690 | { | |
691 | .procname = "inheritable", | |
692 | .data = CAP_PI, | |
693 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
694 | .mode = 0600, | |
695 | .proc_handler = proc_cap_handler, | |
696 | }, | |
697 | { } | |
698 | }; |