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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
23558693 LR |
2 | /* |
3 | * umh - the kernel usermode helper | |
4 | */ | |
5 | #include <linux/module.h> | |
6 | #include <linux/sched.h> | |
7 | #include <linux/sched/task.h> | |
8 | #include <linux/binfmts.h> | |
9 | #include <linux/syscalls.h> | |
10 | #include <linux/unistd.h> | |
11 | #include <linux/kmod.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/completion.h> | |
14 | #include <linux/cred.h> | |
15 | #include <linux/file.h> | |
16 | #include <linux/fdtable.h> | |
a7b8cddd | 17 | #include <linux/fs_struct.h> |
23558693 LR |
18 | #include <linux/workqueue.h> |
19 | #include <linux/security.h> | |
20 | #include <linux/mount.h> | |
21 | #include <linux/kernel.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/resource.h> | |
24 | #include <linux/notifier.h> | |
25 | #include <linux/suspend.h> | |
26 | #include <linux/rwsem.h> | |
27 | #include <linux/ptrace.h> | |
28 | #include <linux/async.h> | |
29 | #include <linux/uaccess.h> | |
449325b5 AS |
30 | #include <linux/shmem_fs.h> |
31 | #include <linux/pipe_fs_i.h> | |
23558693 LR |
32 | |
33 | #include <trace/events/module.h> | |
34 | ||
35 | #define CAP_BSET (void *)1 | |
36 | #define CAP_PI (void *)2 | |
37 | ||
38 | static kernel_cap_t usermodehelper_bset = CAP_FULL_SET; | |
39 | static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET; | |
40 | static DEFINE_SPINLOCK(umh_sysctl_lock); | |
41 | static DECLARE_RWSEM(umhelper_sem); | |
73ab1cb2 TY |
42 | static LIST_HEAD(umh_list); |
43 | static DEFINE_MUTEX(umh_list_lock); | |
23558693 LR |
44 | |
45 | static void call_usermodehelper_freeinfo(struct subprocess_info *info) | |
46 | { | |
47 | if (info->cleanup) | |
48 | (*info->cleanup)(info); | |
49 | kfree(info); | |
50 | } | |
51 | ||
52 | static void umh_complete(struct subprocess_info *sub_info) | |
53 | { | |
54 | struct completion *comp = xchg(&sub_info->complete, NULL); | |
55 | /* | |
56 | * See call_usermodehelper_exec(). If xchg() returns NULL | |
57 | * we own sub_info, the UMH_KILLABLE caller has gone away | |
58 | * or the caller used UMH_NO_WAIT. | |
59 | */ | |
60 | if (comp) | |
61 | complete(comp); | |
62 | else | |
63 | call_usermodehelper_freeinfo(sub_info); | |
64 | } | |
65 | ||
66 | /* | |
67 | * This is the task which runs the usermode application | |
68 | */ | |
69 | static int call_usermodehelper_exec_async(void *data) | |
70 | { | |
71 | struct subprocess_info *sub_info = data; | |
72 | struct cred *new; | |
73 | int retval; | |
74 | ||
75 | spin_lock_irq(¤t->sighand->siglock); | |
76 | flush_signal_handlers(current, 1); | |
77 | spin_unlock_irq(¤t->sighand->siglock); | |
78 | ||
a7b8cddd LT |
79 | /* |
80 | * Initial kernel threads share ther FS with init, in order to | |
81 | * get the init root directory. But we've now created a new | |
82 | * thread that is going to execve a user process and has its own | |
83 | * 'struct fs_struct'. Reset umask to the default. | |
84 | */ | |
85 | current->fs->umask = 0022; | |
86 | ||
23558693 LR |
87 | /* |
88 | * Our parent (unbound workqueue) runs with elevated scheduling | |
89 | * priority. Avoid propagating that into the userspace child. | |
90 | */ | |
91 | set_user_nice(current, 0); | |
92 | ||
93 | retval = -ENOMEM; | |
94 | new = prepare_kernel_cred(current); | |
95 | if (!new) | |
96 | goto out; | |
97 | ||
98 | spin_lock(&umh_sysctl_lock); | |
99 | new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset); | |
100 | new->cap_inheritable = cap_intersect(usermodehelper_inheritable, | |
101 | new->cap_inheritable); | |
102 | spin_unlock(&umh_sysctl_lock); | |
103 | ||
104 | if (sub_info->init) { | |
105 | retval = sub_info->init(sub_info, new); | |
106 | if (retval) { | |
107 | abort_creds(new); | |
108 | goto out; | |
109 | } | |
110 | } | |
111 | ||
112 | commit_creds(new); | |
113 | ||
bf956be5 | 114 | sub_info->pid = task_pid_nr(current); |
73ab1cb2 | 115 | if (sub_info->file) { |
449325b5 AS |
116 | retval = do_execve_file(sub_info->file, |
117 | sub_info->argv, sub_info->envp); | |
73ab1cb2 TY |
118 | if (!retval) |
119 | current->flags |= PF_UMH; | |
120 | } else | |
449325b5 AS |
121 | retval = do_execve(getname_kernel(sub_info->path), |
122 | (const char __user *const __user *)sub_info->argv, | |
123 | (const char __user *const __user *)sub_info->envp); | |
23558693 LR |
124 | out: |
125 | sub_info->retval = retval; | |
126 | /* | |
127 | * call_usermodehelper_exec_sync() will call umh_complete | |
128 | * if UHM_WAIT_PROC. | |
129 | */ | |
130 | if (!(sub_info->wait & UMH_WAIT_PROC)) | |
131 | umh_complete(sub_info); | |
132 | if (!retval) | |
133 | return 0; | |
134 | do_exit(0); | |
135 | } | |
136 | ||
137 | /* Handles UMH_WAIT_PROC. */ | |
138 | static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info) | |
139 | { | |
140 | pid_t pid; | |
141 | ||
d300b610 | 142 | /* If SIGCLD is ignored kernel_wait4 won't populate the status. */ |
23558693 LR |
143 | kernel_sigaction(SIGCHLD, SIG_DFL); |
144 | pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD); | |
145 | if (pid < 0) { | |
146 | sub_info->retval = pid; | |
147 | } else { | |
148 | int ret = -ECHILD; | |
149 | /* | |
150 | * Normally it is bogus to call wait4() from in-kernel because | |
151 | * wait4() wants to write the exit code to a userspace address. | |
152 | * But call_usermodehelper_exec_sync() always runs as kernel | |
153 | * thread (workqueue) and put_user() to a kernel address works | |
154 | * OK for kernel threads, due to their having an mm_segment_t | |
155 | * which spans the entire address space. | |
156 | * | |
157 | * Thus the __user pointer cast is valid here. | |
158 | */ | |
d300b610 | 159 | kernel_wait4(pid, (int __user *)&ret, 0, NULL); |
23558693 LR |
160 | |
161 | /* | |
162 | * If ret is 0, either call_usermodehelper_exec_async failed and | |
163 | * the real error code is already in sub_info->retval or | |
164 | * sub_info->retval is 0 anyway, so don't mess with it then. | |
165 | */ | |
166 | if (ret) | |
167 | sub_info->retval = ret; | |
168 | } | |
169 | ||
170 | /* Restore default kernel sig handler */ | |
171 | kernel_sigaction(SIGCHLD, SIG_IGN); | |
172 | ||
173 | umh_complete(sub_info); | |
174 | } | |
175 | ||
176 | /* | |
177 | * We need to create the usermodehelper kernel thread from a task that is affine | |
178 | * to an optimized set of CPUs (or nohz housekeeping ones) such that they | |
179 | * inherit a widest affinity irrespective of call_usermodehelper() callers with | |
180 | * possibly reduced affinity (eg: per-cpu workqueues). We don't want | |
181 | * usermodehelper targets to contend a busy CPU. | |
182 | * | |
183 | * Unbound workqueues provide such wide affinity and allow to block on | |
184 | * UMH_WAIT_PROC requests without blocking pending request (up to some limit). | |
185 | * | |
186 | * Besides, workqueues provide the privilege level that caller might not have | |
187 | * to perform the usermodehelper request. | |
188 | * | |
189 | */ | |
190 | static void call_usermodehelper_exec_work(struct work_struct *work) | |
191 | { | |
192 | struct subprocess_info *sub_info = | |
193 | container_of(work, struct subprocess_info, work); | |
194 | ||
195 | if (sub_info->wait & UMH_WAIT_PROC) { | |
196 | call_usermodehelper_exec_sync(sub_info); | |
197 | } else { | |
198 | pid_t pid; | |
199 | /* | |
200 | * Use CLONE_PARENT to reparent it to kthreadd; we do not | |
201 | * want to pollute current->children, and we need a parent | |
202 | * that always ignores SIGCHLD to ensure auto-reaping. | |
203 | */ | |
204 | pid = kernel_thread(call_usermodehelper_exec_async, sub_info, | |
205 | CLONE_PARENT | SIGCHLD); | |
206 | if (pid < 0) { | |
207 | sub_info->retval = pid; | |
208 | umh_complete(sub_info); | |
209 | } | |
210 | } | |
211 | } | |
212 | ||
213 | /* | |
214 | * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY | |
215 | * (used for preventing user land processes from being created after the user | |
216 | * land has been frozen during a system-wide hibernation or suspend operation). | |
217 | * Should always be manipulated under umhelper_sem acquired for write. | |
218 | */ | |
219 | static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED; | |
220 | ||
221 | /* Number of helpers running */ | |
222 | static atomic_t running_helpers = ATOMIC_INIT(0); | |
223 | ||
224 | /* | |
225 | * Wait queue head used by usermodehelper_disable() to wait for all running | |
226 | * helpers to finish. | |
227 | */ | |
228 | static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); | |
229 | ||
230 | /* | |
231 | * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled | |
232 | * to become 'false'. | |
233 | */ | |
234 | static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq); | |
235 | ||
236 | /* | |
237 | * Time to wait for running_helpers to become zero before the setting of | |
238 | * usermodehelper_disabled in usermodehelper_disable() fails | |
239 | */ | |
240 | #define RUNNING_HELPERS_TIMEOUT (5 * HZ) | |
241 | ||
242 | int usermodehelper_read_trylock(void) | |
243 | { | |
244 | DEFINE_WAIT(wait); | |
245 | int ret = 0; | |
246 | ||
247 | down_read(&umhelper_sem); | |
248 | for (;;) { | |
249 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
250 | TASK_INTERRUPTIBLE); | |
251 | if (!usermodehelper_disabled) | |
252 | break; | |
253 | ||
254 | if (usermodehelper_disabled == UMH_DISABLED) | |
255 | ret = -EAGAIN; | |
256 | ||
257 | up_read(&umhelper_sem); | |
258 | ||
259 | if (ret) | |
260 | break; | |
261 | ||
262 | schedule(); | |
263 | try_to_freeze(); | |
264 | ||
265 | down_read(&umhelper_sem); | |
266 | } | |
267 | finish_wait(&usermodehelper_disabled_waitq, &wait); | |
268 | return ret; | |
269 | } | |
270 | EXPORT_SYMBOL_GPL(usermodehelper_read_trylock); | |
271 | ||
272 | long usermodehelper_read_lock_wait(long timeout) | |
273 | { | |
274 | DEFINE_WAIT(wait); | |
275 | ||
276 | if (timeout < 0) | |
277 | return -EINVAL; | |
278 | ||
279 | down_read(&umhelper_sem); | |
280 | for (;;) { | |
281 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
282 | TASK_UNINTERRUPTIBLE); | |
283 | if (!usermodehelper_disabled) | |
284 | break; | |
285 | ||
286 | up_read(&umhelper_sem); | |
287 | ||
288 | timeout = schedule_timeout(timeout); | |
289 | if (!timeout) | |
290 | break; | |
291 | ||
292 | down_read(&umhelper_sem); | |
293 | } | |
294 | finish_wait(&usermodehelper_disabled_waitq, &wait); | |
295 | return timeout; | |
296 | } | |
297 | EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait); | |
298 | ||
299 | void usermodehelper_read_unlock(void) | |
300 | { | |
301 | up_read(&umhelper_sem); | |
302 | } | |
303 | EXPORT_SYMBOL_GPL(usermodehelper_read_unlock); | |
304 | ||
305 | /** | |
306 | * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled. | |
307 | * @depth: New value to assign to usermodehelper_disabled. | |
308 | * | |
309 | * Change the value of usermodehelper_disabled (under umhelper_sem locked for | |
310 | * writing) and wakeup tasks waiting for it to change. | |
311 | */ | |
312 | void __usermodehelper_set_disable_depth(enum umh_disable_depth depth) | |
313 | { | |
314 | down_write(&umhelper_sem); | |
315 | usermodehelper_disabled = depth; | |
316 | wake_up(&usermodehelper_disabled_waitq); | |
317 | up_write(&umhelper_sem); | |
318 | } | |
319 | ||
320 | /** | |
321 | * __usermodehelper_disable - Prevent new helpers from being started. | |
322 | * @depth: New value to assign to usermodehelper_disabled. | |
323 | * | |
324 | * Set usermodehelper_disabled to @depth and wait for running helpers to exit. | |
325 | */ | |
326 | int __usermodehelper_disable(enum umh_disable_depth depth) | |
327 | { | |
328 | long retval; | |
329 | ||
330 | if (!depth) | |
331 | return -EINVAL; | |
332 | ||
333 | down_write(&umhelper_sem); | |
334 | usermodehelper_disabled = depth; | |
335 | up_write(&umhelper_sem); | |
336 | ||
337 | /* | |
338 | * From now on call_usermodehelper_exec() won't start any new | |
339 | * helpers, so it is sufficient if running_helpers turns out to | |
340 | * be zero at one point (it may be increased later, but that | |
341 | * doesn't matter). | |
342 | */ | |
343 | retval = wait_event_timeout(running_helpers_waitq, | |
344 | atomic_read(&running_helpers) == 0, | |
345 | RUNNING_HELPERS_TIMEOUT); | |
346 | if (retval) | |
347 | return 0; | |
348 | ||
349 | __usermodehelper_set_disable_depth(UMH_ENABLED); | |
350 | return -EAGAIN; | |
351 | } | |
352 | ||
353 | static void helper_lock(void) | |
354 | { | |
355 | atomic_inc(&running_helpers); | |
356 | smp_mb__after_atomic(); | |
357 | } | |
358 | ||
359 | static void helper_unlock(void) | |
360 | { | |
361 | if (atomic_dec_and_test(&running_helpers)) | |
362 | wake_up(&running_helpers_waitq); | |
363 | } | |
364 | ||
365 | /** | |
366 | * call_usermodehelper_setup - prepare to call a usermode helper | |
367 | * @path: path to usermode executable | |
368 | * @argv: arg vector for process | |
369 | * @envp: environment for process | |
370 | * @gfp_mask: gfp mask for memory allocation | |
371 | * @cleanup: a cleanup function | |
372 | * @init: an init function | |
373 | * @data: arbitrary context sensitive data | |
374 | * | |
375 | * Returns either %NULL on allocation failure, or a subprocess_info | |
376 | * structure. This should be passed to call_usermodehelper_exec to | |
377 | * exec the process and free the structure. | |
378 | * | |
379 | * The init function is used to customize the helper process prior to | |
380 | * exec. A non-zero return code causes the process to error out, exit, | |
381 | * and return the failure to the calling process | |
382 | * | |
383 | * The cleanup function is just before ethe subprocess_info is about to | |
384 | * be freed. This can be used for freeing the argv and envp. The | |
385 | * Function must be runnable in either a process context or the | |
386 | * context in which call_usermodehelper_exec is called. | |
387 | */ | |
388 | struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv, | |
389 | char **envp, gfp_t gfp_mask, | |
390 | int (*init)(struct subprocess_info *info, struct cred *new), | |
391 | void (*cleanup)(struct subprocess_info *info), | |
392 | void *data) | |
393 | { | |
394 | struct subprocess_info *sub_info; | |
395 | sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask); | |
396 | if (!sub_info) | |
397 | goto out; | |
398 | ||
399 | INIT_WORK(&sub_info->work, call_usermodehelper_exec_work); | |
400 | ||
401 | #ifdef CONFIG_STATIC_USERMODEHELPER | |
402 | sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH; | |
403 | #else | |
404 | sub_info->path = path; | |
405 | #endif | |
406 | sub_info->argv = argv; | |
407 | sub_info->envp = envp; | |
408 | ||
409 | sub_info->cleanup = cleanup; | |
410 | sub_info->init = init; | |
411 | sub_info->data = data; | |
412 | out: | |
413 | return sub_info; | |
414 | } | |
415 | EXPORT_SYMBOL(call_usermodehelper_setup); | |
416 | ||
449325b5 AS |
417 | struct subprocess_info *call_usermodehelper_setup_file(struct file *file, |
418 | int (*init)(struct subprocess_info *info, struct cred *new), | |
419 | void (*cleanup)(struct subprocess_info *info), void *data) | |
420 | { | |
421 | struct subprocess_info *sub_info; | |
876dcf2f OB |
422 | struct umh_info *info = data; |
423 | const char *cmdline = (info->cmdline) ? info->cmdline : "usermodehelper"; | |
449325b5 AS |
424 | |
425 | sub_info = kzalloc(sizeof(struct subprocess_info), GFP_KERNEL); | |
426 | if (!sub_info) | |
427 | return NULL; | |
428 | ||
876dcf2f OB |
429 | sub_info->argv = argv_split(GFP_KERNEL, cmdline, NULL); |
430 | if (!sub_info->argv) { | |
431 | kfree(sub_info); | |
432 | return NULL; | |
433 | } | |
434 | ||
449325b5 AS |
435 | INIT_WORK(&sub_info->work, call_usermodehelper_exec_work); |
436 | sub_info->path = "none"; | |
437 | sub_info->file = file; | |
438 | sub_info->init = init; | |
439 | sub_info->cleanup = cleanup; | |
440 | sub_info->data = data; | |
441 | return sub_info; | |
442 | } | |
443 | ||
444 | static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) | |
445 | { | |
446 | struct umh_info *umh_info = info->data; | |
447 | struct file *from_umh[2]; | |
448 | struct file *to_umh[2]; | |
449 | int err; | |
450 | ||
451 | /* create pipe to send data to umh */ | |
452 | err = create_pipe_files(to_umh, 0); | |
453 | if (err) | |
454 | return err; | |
455 | err = replace_fd(0, to_umh[0], 0); | |
456 | fput(to_umh[0]); | |
457 | if (err < 0) { | |
458 | fput(to_umh[1]); | |
459 | return err; | |
460 | } | |
461 | ||
462 | /* create pipe to receive data from umh */ | |
463 | err = create_pipe_files(from_umh, 0); | |
464 | if (err) { | |
465 | fput(to_umh[1]); | |
466 | replace_fd(0, NULL, 0); | |
467 | return err; | |
468 | } | |
469 | err = replace_fd(1, from_umh[1], 0); | |
470 | fput(from_umh[1]); | |
471 | if (err < 0) { | |
472 | fput(to_umh[1]); | |
473 | replace_fd(0, NULL, 0); | |
474 | fput(from_umh[0]); | |
475 | return err; | |
476 | } | |
477 | ||
478 | umh_info->pipe_to_umh = to_umh[1]; | |
479 | umh_info->pipe_from_umh = from_umh[0]; | |
480 | return 0; | |
481 | } | |
482 | ||
876dcf2f | 483 | static void umh_clean_and_save_pid(struct subprocess_info *info) |
449325b5 AS |
484 | { |
485 | struct umh_info *umh_info = info->data; | |
486 | ||
d2947017 VM |
487 | /* cleanup if umh_pipe_setup() was successful but exec failed */ |
488 | if (info->pid && info->retval) { | |
489 | fput(umh_info->pipe_to_umh); | |
490 | fput(umh_info->pipe_from_umh); | |
491 | } | |
492 | ||
876dcf2f | 493 | argv_free(info->argv); |
449325b5 AS |
494 | umh_info->pid = info->pid; |
495 | } | |
496 | ||
497 | /** | |
498 | * fork_usermode_blob - fork a blob of bytes as a usermode process | |
499 | * @data: a blob of bytes that can be do_execv-ed as a file | |
500 | * @len: length of the blob | |
501 | * @info: information about usermode process (shouldn't be NULL) | |
502 | * | |
876dcf2f OB |
503 | * If info->cmdline is set it will be used as command line for the |
504 | * user process, else "usermodehelper" is used. | |
505 | * | |
449325b5 AS |
506 | * Returns either negative error or zero which indicates success |
507 | * in executing a blob of bytes as a usermode process. In such | |
508 | * case 'struct umh_info *info' is populated with two pipes | |
509 | * and a pid of the process. The caller is responsible for health | |
510 | * check of the user process, killing it via pid, and closing the | |
511 | * pipes when user process is no longer needed. | |
512 | */ | |
513 | int fork_usermode_blob(void *data, size_t len, struct umh_info *info) | |
514 | { | |
515 | struct subprocess_info *sub_info; | |
516 | struct file *file; | |
517 | ssize_t written; | |
518 | loff_t pos = 0; | |
519 | int err; | |
520 | ||
521 | file = shmem_kernel_file_setup("", len, 0); | |
522 | if (IS_ERR(file)) | |
523 | return PTR_ERR(file); | |
524 | ||
525 | written = kernel_write(file, data, len, &pos); | |
526 | if (written != len) { | |
527 | err = written; | |
528 | if (err >= 0) | |
529 | err = -ENOMEM; | |
530 | goto out; | |
531 | } | |
532 | ||
533 | err = -ENOMEM; | |
534 | sub_info = call_usermodehelper_setup_file(file, umh_pipe_setup, | |
876dcf2f | 535 | umh_clean_and_save_pid, info); |
449325b5 AS |
536 | if (!sub_info) |
537 | goto out; | |
538 | ||
539 | err = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC); | |
73ab1cb2 TY |
540 | if (!err) { |
541 | mutex_lock(&umh_list_lock); | |
542 | list_add(&info->list, &umh_list); | |
543 | mutex_unlock(&umh_list_lock); | |
544 | } | |
449325b5 AS |
545 | out: |
546 | fput(file); | |
547 | return err; | |
548 | } | |
549 | EXPORT_SYMBOL_GPL(fork_usermode_blob); | |
550 | ||
23558693 LR |
551 | /** |
552 | * call_usermodehelper_exec - start a usermode application | |
553 | * @sub_info: information about the subprocessa | |
554 | * @wait: wait for the application to finish and return status. | |
555 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back | |
556 | * when the program couldn't be exec'ed. This makes it safe to call | |
557 | * from interrupt context. | |
558 | * | |
559 | * Runs a user-space application. The application is started | |
560 | * asynchronously if wait is not set, and runs as a child of system workqueues. | |
561 | * (ie. it runs with full root capabilities and optimized affinity). | |
2f9829cc LC |
562 | * |
563 | * Note: successful return value does not guarantee the helper was called at | |
564 | * all. You can't rely on sub_info->{init,cleanup} being called even for | |
565 | * UMH_WAIT_* wait modes as STATIC_USERMODEHELPER_PATH="" turns all helpers | |
566 | * into a successful no-op. | |
23558693 LR |
567 | */ |
568 | int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) | |
569 | { | |
570 | DECLARE_COMPLETION_ONSTACK(done); | |
571 | int retval = 0; | |
572 | ||
573 | if (!sub_info->path) { | |
574 | call_usermodehelper_freeinfo(sub_info); | |
575 | return -EINVAL; | |
576 | } | |
577 | helper_lock(); | |
578 | if (usermodehelper_disabled) { | |
579 | retval = -EBUSY; | |
580 | goto out; | |
581 | } | |
582 | ||
583 | /* | |
584 | * If there is no binary for us to call, then just return and get out of | |
585 | * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and | |
586 | * disable all call_usermodehelper() calls. | |
587 | */ | |
588 | if (strlen(sub_info->path) == 0) | |
589 | goto out; | |
590 | ||
591 | /* | |
592 | * Set the completion pointer only if there is a waiter. | |
593 | * This makes it possible to use umh_complete to free | |
594 | * the data structure in case of UMH_NO_WAIT. | |
595 | */ | |
596 | sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done; | |
597 | sub_info->wait = wait; | |
598 | ||
599 | queue_work(system_unbound_wq, &sub_info->work); | |
600 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ | |
601 | goto unlock; | |
602 | ||
603 | if (wait & UMH_KILLABLE) { | |
604 | retval = wait_for_completion_killable(&done); | |
605 | if (!retval) | |
606 | goto wait_done; | |
607 | ||
608 | /* umh_complete() will see NULL and free sub_info */ | |
609 | if (xchg(&sub_info->complete, NULL)) | |
610 | goto unlock; | |
611 | /* fallthrough, umh_complete() was already called */ | |
612 | } | |
613 | ||
614 | wait_for_completion(&done); | |
615 | wait_done: | |
616 | retval = sub_info->retval; | |
617 | out: | |
618 | call_usermodehelper_freeinfo(sub_info); | |
619 | unlock: | |
620 | helper_unlock(); | |
621 | return retval; | |
622 | } | |
623 | EXPORT_SYMBOL(call_usermodehelper_exec); | |
624 | ||
625 | /** | |
626 | * call_usermodehelper() - prepare and start a usermode application | |
627 | * @path: path to usermode executable | |
628 | * @argv: arg vector for process | |
629 | * @envp: environment for process | |
630 | * @wait: wait for the application to finish and return status. | |
631 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back | |
632 | * when the program couldn't be exec'ed. This makes it safe to call | |
633 | * from interrupt context. | |
634 | * | |
635 | * This function is the equivalent to use call_usermodehelper_setup() and | |
636 | * call_usermodehelper_exec(). | |
637 | */ | |
638 | int call_usermodehelper(const char *path, char **argv, char **envp, int wait) | |
639 | { | |
640 | struct subprocess_info *info; | |
641 | gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL; | |
642 | ||
643 | info = call_usermodehelper_setup(path, argv, envp, gfp_mask, | |
644 | NULL, NULL, NULL); | |
645 | if (info == NULL) | |
646 | return -ENOMEM; | |
647 | ||
648 | return call_usermodehelper_exec(info, wait); | |
649 | } | |
650 | EXPORT_SYMBOL(call_usermodehelper); | |
651 | ||
652 | static int proc_cap_handler(struct ctl_table *table, int write, | |
653 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
654 | { | |
655 | struct ctl_table t; | |
656 | unsigned long cap_array[_KERNEL_CAPABILITY_U32S]; | |
657 | kernel_cap_t new_cap; | |
658 | int err, i; | |
659 | ||
660 | if (write && (!capable(CAP_SETPCAP) || | |
661 | !capable(CAP_SYS_MODULE))) | |
662 | return -EPERM; | |
663 | ||
664 | /* | |
665 | * convert from the global kernel_cap_t to the ulong array to print to | |
666 | * userspace if this is a read. | |
667 | */ | |
668 | spin_lock(&umh_sysctl_lock); | |
669 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) { | |
670 | if (table->data == CAP_BSET) | |
671 | cap_array[i] = usermodehelper_bset.cap[i]; | |
672 | else if (table->data == CAP_PI) | |
673 | cap_array[i] = usermodehelper_inheritable.cap[i]; | |
674 | else | |
675 | BUG(); | |
676 | } | |
677 | spin_unlock(&umh_sysctl_lock); | |
678 | ||
679 | t = *table; | |
680 | t.data = &cap_array; | |
681 | ||
682 | /* | |
683 | * actually read or write and array of ulongs from userspace. Remember | |
684 | * these are least significant 32 bits first | |
685 | */ | |
686 | err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); | |
687 | if (err < 0) | |
688 | return err; | |
689 | ||
690 | /* | |
691 | * convert from the sysctl array of ulongs to the kernel_cap_t | |
692 | * internal representation | |
693 | */ | |
694 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) | |
695 | new_cap.cap[i] = cap_array[i]; | |
696 | ||
697 | /* | |
698 | * Drop everything not in the new_cap (but don't add things) | |
699 | */ | |
23558693 | 700 | if (write) { |
8c703d66 | 701 | spin_lock(&umh_sysctl_lock); |
23558693 LR |
702 | if (table->data == CAP_BSET) |
703 | usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap); | |
704 | if (table->data == CAP_PI) | |
705 | usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap); | |
8c703d66 | 706 | spin_unlock(&umh_sysctl_lock); |
23558693 | 707 | } |
23558693 LR |
708 | |
709 | return 0; | |
710 | } | |
711 | ||
73ab1cb2 TY |
712 | void __exit_umh(struct task_struct *tsk) |
713 | { | |
714 | struct umh_info *info; | |
715 | pid_t pid = tsk->pid; | |
716 | ||
717 | mutex_lock(&umh_list_lock); | |
718 | list_for_each_entry(info, &umh_list, list) { | |
719 | if (info->pid == pid) { | |
720 | list_del(&info->list); | |
721 | mutex_unlock(&umh_list_lock); | |
722 | goto out; | |
723 | } | |
724 | } | |
725 | mutex_unlock(&umh_list_lock); | |
726 | return; | |
727 | out: | |
728 | if (info->cleanup) | |
729 | info->cleanup(info); | |
730 | } | |
731 | ||
23558693 LR |
732 | struct ctl_table usermodehelper_table[] = { |
733 | { | |
734 | .procname = "bset", | |
735 | .data = CAP_BSET, | |
736 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
737 | .mode = 0600, | |
738 | .proc_handler = proc_cap_handler, | |
739 | }, | |
740 | { | |
741 | .procname = "inheritable", | |
742 | .data = CAP_PI, | |
743 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
744 | .mode = 0600, | |
745 | .proc_handler = proc_cap_handler, | |
746 | }, | |
747 | { } | |
748 | }; |