]>
Commit | Line | Data |
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1 | /* | |
2 | kmod, the new module loader (replaces kerneld) | |
3 | Kirk Petersen | |
4 | ||
5 | Reorganized not to be a daemon by Adam Richter, with guidance | |
6 | from Greg Zornetzer. | |
7 | ||
8 | Modified to avoid chroot and file sharing problems. | |
9 | Mikael Pettersson | |
10 | ||
11 | Limit the concurrent number of kmod modprobes to catch loops from | |
12 | "modprobe needs a service that is in a module". | |
13 | Keith Owens <kaos@ocs.com.au> December 1999 | |
14 | ||
15 | Unblock all signals when we exec a usermode process. | |
16 | Shuu Yamaguchi <shuu@wondernetworkresources.com> December 2000 | |
17 | ||
18 | call_usermodehelper wait flag, and remove exec_usermodehelper. | |
19 | Rusty Russell <rusty@rustcorp.com.au> Jan 2003 | |
20 | */ | |
21 | #include <linux/module.h> | |
22 | #include <linux/sched.h> | |
23 | #include <linux/sched/task.h> | |
24 | #include <linux/binfmts.h> | |
25 | #include <linux/syscalls.h> | |
26 | #include <linux/unistd.h> | |
27 | #include <linux/kmod.h> | |
28 | #include <linux/slab.h> | |
29 | #include <linux/completion.h> | |
30 | #include <linux/cred.h> | |
31 | #include <linux/file.h> | |
32 | #include <linux/fdtable.h> | |
33 | #include <linux/workqueue.h> | |
34 | #include <linux/security.h> | |
35 | #include <linux/mount.h> | |
36 | #include <linux/kernel.h> | |
37 | #include <linux/init.h> | |
38 | #include <linux/resource.h> | |
39 | #include <linux/notifier.h> | |
40 | #include <linux/suspend.h> | |
41 | #include <linux/rwsem.h> | |
42 | #include <linux/ptrace.h> | |
43 | #include <linux/async.h> | |
44 | #include <linux/uaccess.h> | |
45 | ||
46 | #include <trace/events/module.h> | |
47 | ||
48 | #define CAP_BSET (void *)1 | |
49 | #define CAP_PI (void *)2 | |
50 | ||
51 | static kernel_cap_t usermodehelper_bset = CAP_FULL_SET; | |
52 | static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET; | |
53 | static DEFINE_SPINLOCK(umh_sysctl_lock); | |
54 | static DECLARE_RWSEM(umhelper_sem); | |
55 | ||
56 | #ifdef CONFIG_MODULES | |
57 | /* | |
58 | * Assuming: | |
59 | * | |
60 | * threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE, | |
61 | * (u64) THREAD_SIZE * 8UL); | |
62 | * | |
63 | * If you need less than 50 threads would mean we're dealing with systems | |
64 | * smaller than 3200 pages. This assuems you are capable of having ~13M memory, | |
65 | * and this would only be an be an upper limit, after which the OOM killer | |
66 | * would take effect. Systems like these are very unlikely if modules are | |
67 | * enabled. | |
68 | */ | |
69 | #define MAX_KMOD_CONCURRENT 50 | |
70 | static atomic_t kmod_concurrent_max = ATOMIC_INIT(MAX_KMOD_CONCURRENT); | |
71 | static DECLARE_WAIT_QUEUE_HEAD(kmod_wq); | |
72 | ||
73 | /* | |
74 | * This is a restriction on having *all* MAX_KMOD_CONCURRENT threads | |
75 | * running at the same time without returning. When this happens we | |
76 | * believe you've somehow ended up with a recursive module dependency | |
77 | * creating a loop. | |
78 | * | |
79 | * We have no option but to fail. | |
80 | * | |
81 | * Userspace should proactively try to detect and prevent these. | |
82 | */ | |
83 | #define MAX_KMOD_ALL_BUSY_TIMEOUT 5 | |
84 | ||
85 | /* | |
86 | modprobe_path is set via /proc/sys. | |
87 | */ | |
88 | char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe"; | |
89 | ||
90 | static void free_modprobe_argv(struct subprocess_info *info) | |
91 | { | |
92 | kfree(info->argv[3]); /* check call_modprobe() */ | |
93 | kfree(info->argv); | |
94 | } | |
95 | ||
96 | static int call_modprobe(char *module_name, int wait) | |
97 | { | |
98 | struct subprocess_info *info; | |
99 | static char *envp[] = { | |
100 | "HOME=/", | |
101 | "TERM=linux", | |
102 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
103 | NULL | |
104 | }; | |
105 | ||
106 | char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL); | |
107 | if (!argv) | |
108 | goto out; | |
109 | ||
110 | module_name = kstrdup(module_name, GFP_KERNEL); | |
111 | if (!module_name) | |
112 | goto free_argv; | |
113 | ||
114 | argv[0] = modprobe_path; | |
115 | argv[1] = "-q"; | |
116 | argv[2] = "--"; | |
117 | argv[3] = module_name; /* check free_modprobe_argv() */ | |
118 | argv[4] = NULL; | |
119 | ||
120 | info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL, | |
121 | NULL, free_modprobe_argv, NULL); | |
122 | if (!info) | |
123 | goto free_module_name; | |
124 | ||
125 | return call_usermodehelper_exec(info, wait | UMH_KILLABLE); | |
126 | ||
127 | free_module_name: | |
128 | kfree(module_name); | |
129 | free_argv: | |
130 | kfree(argv); | |
131 | out: | |
132 | return -ENOMEM; | |
133 | } | |
134 | ||
135 | /** | |
136 | * __request_module - try to load a kernel module | |
137 | * @wait: wait (or not) for the operation to complete | |
138 | * @fmt: printf style format string for the name of the module | |
139 | * @...: arguments as specified in the format string | |
140 | * | |
141 | * Load a module using the user mode module loader. The function returns | |
142 | * zero on success or a negative errno code or positive exit code from | |
143 | * "modprobe" on failure. Note that a successful module load does not mean | |
144 | * the module did not then unload and exit on an error of its own. Callers | |
145 | * must check that the service they requested is now available not blindly | |
146 | * invoke it. | |
147 | * | |
148 | * If module auto-loading support is disabled then this function | |
149 | * becomes a no-operation. | |
150 | */ | |
151 | int __request_module(bool wait, const char *fmt, ...) | |
152 | { | |
153 | va_list args; | |
154 | char module_name[MODULE_NAME_LEN]; | |
155 | int ret; | |
156 | ||
157 | /* | |
158 | * We don't allow synchronous module loading from async. Module | |
159 | * init may invoke async_synchronize_full() which will end up | |
160 | * waiting for this task which already is waiting for the module | |
161 | * loading to complete, leading to a deadlock. | |
162 | */ | |
163 | WARN_ON_ONCE(wait && current_is_async()); | |
164 | ||
165 | if (!modprobe_path[0]) | |
166 | return 0; | |
167 | ||
168 | va_start(args, fmt); | |
169 | ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args); | |
170 | va_end(args); | |
171 | if (ret >= MODULE_NAME_LEN) | |
172 | return -ENAMETOOLONG; | |
173 | ||
174 | ret = security_kernel_module_request(module_name); | |
175 | if (ret) | |
176 | return ret; | |
177 | ||
178 | if (atomic_dec_if_positive(&kmod_concurrent_max) < 0) { | |
179 | pr_warn_ratelimited("request_module: kmod_concurrent_max (%u) close to 0 (max_modprobes: %u), for module %s, throttling...", | |
180 | atomic_read(&kmod_concurrent_max), | |
181 | MAX_KMOD_CONCURRENT, module_name); | |
182 | ret = wait_event_killable_timeout(kmod_wq, | |
183 | atomic_dec_if_positive(&kmod_concurrent_max) >= 0, | |
184 | MAX_KMOD_ALL_BUSY_TIMEOUT * HZ); | |
185 | if (!ret) { | |
186 | pr_warn_ratelimited("request_module: modprobe %s cannot be processed, kmod busy with %d threads for more than %d seconds now", | |
187 | module_name, MAX_KMOD_CONCURRENT, MAX_KMOD_ALL_BUSY_TIMEOUT); | |
188 | return -ETIME; | |
189 | } else if (ret == -ERESTARTSYS) { | |
190 | pr_warn_ratelimited("request_module: sigkill sent for modprobe %s, giving up", module_name); | |
191 | return ret; | |
192 | } | |
193 | } | |
194 | ||
195 | trace_module_request(module_name, wait, _RET_IP_); | |
196 | ||
197 | ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC); | |
198 | ||
199 | atomic_inc(&kmod_concurrent_max); | |
200 | wake_up(&kmod_wq); | |
201 | ||
202 | return ret; | |
203 | } | |
204 | EXPORT_SYMBOL(__request_module); | |
205 | ||
206 | #endif /* CONFIG_MODULES */ | |
207 | ||
208 | static void call_usermodehelper_freeinfo(struct subprocess_info *info) | |
209 | { | |
210 | if (info->cleanup) | |
211 | (*info->cleanup)(info); | |
212 | kfree(info); | |
213 | } | |
214 | ||
215 | static void umh_complete(struct subprocess_info *sub_info) | |
216 | { | |
217 | struct completion *comp = xchg(&sub_info->complete, NULL); | |
218 | /* | |
219 | * See call_usermodehelper_exec(). If xchg() returns NULL | |
220 | * we own sub_info, the UMH_KILLABLE caller has gone away | |
221 | * or the caller used UMH_NO_WAIT. | |
222 | */ | |
223 | if (comp) | |
224 | complete(comp); | |
225 | else | |
226 | call_usermodehelper_freeinfo(sub_info); | |
227 | } | |
228 | ||
229 | /* | |
230 | * This is the task which runs the usermode application | |
231 | */ | |
232 | static int call_usermodehelper_exec_async(void *data) | |
233 | { | |
234 | struct subprocess_info *sub_info = data; | |
235 | struct cred *new; | |
236 | int retval; | |
237 | ||
238 | spin_lock_irq(¤t->sighand->siglock); | |
239 | flush_signal_handlers(current, 1); | |
240 | spin_unlock_irq(¤t->sighand->siglock); | |
241 | ||
242 | /* | |
243 | * Our parent (unbound workqueue) runs with elevated scheduling | |
244 | * priority. Avoid propagating that into the userspace child. | |
245 | */ | |
246 | set_user_nice(current, 0); | |
247 | ||
248 | retval = -ENOMEM; | |
249 | new = prepare_kernel_cred(current); | |
250 | if (!new) | |
251 | goto out; | |
252 | ||
253 | spin_lock(&umh_sysctl_lock); | |
254 | new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset); | |
255 | new->cap_inheritable = cap_intersect(usermodehelper_inheritable, | |
256 | new->cap_inheritable); | |
257 | spin_unlock(&umh_sysctl_lock); | |
258 | ||
259 | if (sub_info->init) { | |
260 | retval = sub_info->init(sub_info, new); | |
261 | if (retval) { | |
262 | abort_creds(new); | |
263 | goto out; | |
264 | } | |
265 | } | |
266 | ||
267 | commit_creds(new); | |
268 | ||
269 | retval = do_execve(getname_kernel(sub_info->path), | |
270 | (const char __user *const __user *)sub_info->argv, | |
271 | (const char __user *const __user *)sub_info->envp); | |
272 | out: | |
273 | sub_info->retval = retval; | |
274 | /* | |
275 | * call_usermodehelper_exec_sync() will call umh_complete | |
276 | * if UHM_WAIT_PROC. | |
277 | */ | |
278 | if (!(sub_info->wait & UMH_WAIT_PROC)) | |
279 | umh_complete(sub_info); | |
280 | if (!retval) | |
281 | return 0; | |
282 | do_exit(0); | |
283 | } | |
284 | ||
285 | /* Handles UMH_WAIT_PROC. */ | |
286 | static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info) | |
287 | { | |
288 | pid_t pid; | |
289 | ||
290 | /* If SIGCLD is ignored sys_wait4 won't populate the status. */ | |
291 | kernel_sigaction(SIGCHLD, SIG_DFL); | |
292 | pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD); | |
293 | if (pid < 0) { | |
294 | sub_info->retval = pid; | |
295 | } else { | |
296 | int ret = -ECHILD; | |
297 | /* | |
298 | * Normally it is bogus to call wait4() from in-kernel because | |
299 | * wait4() wants to write the exit code to a userspace address. | |
300 | * But call_usermodehelper_exec_sync() always runs as kernel | |
301 | * thread (workqueue) and put_user() to a kernel address works | |
302 | * OK for kernel threads, due to their having an mm_segment_t | |
303 | * which spans the entire address space. | |
304 | * | |
305 | * Thus the __user pointer cast is valid here. | |
306 | */ | |
307 | sys_wait4(pid, (int __user *)&ret, 0, NULL); | |
308 | ||
309 | /* | |
310 | * If ret is 0, either call_usermodehelper_exec_async failed and | |
311 | * the real error code is already in sub_info->retval or | |
312 | * sub_info->retval is 0 anyway, so don't mess with it then. | |
313 | */ | |
314 | if (ret) | |
315 | sub_info->retval = ret; | |
316 | } | |
317 | ||
318 | /* Restore default kernel sig handler */ | |
319 | kernel_sigaction(SIGCHLD, SIG_IGN); | |
320 | ||
321 | umh_complete(sub_info); | |
322 | } | |
323 | ||
324 | /* | |
325 | * We need to create the usermodehelper kernel thread from a task that is affine | |
326 | * to an optimized set of CPUs (or nohz housekeeping ones) such that they | |
327 | * inherit a widest affinity irrespective of call_usermodehelper() callers with | |
328 | * possibly reduced affinity (eg: per-cpu workqueues). We don't want | |
329 | * usermodehelper targets to contend a busy CPU. | |
330 | * | |
331 | * Unbound workqueues provide such wide affinity and allow to block on | |
332 | * UMH_WAIT_PROC requests without blocking pending request (up to some limit). | |
333 | * | |
334 | * Besides, workqueues provide the privilege level that caller might not have | |
335 | * to perform the usermodehelper request. | |
336 | * | |
337 | */ | |
338 | static void call_usermodehelper_exec_work(struct work_struct *work) | |
339 | { | |
340 | struct subprocess_info *sub_info = | |
341 | container_of(work, struct subprocess_info, work); | |
342 | ||
343 | if (sub_info->wait & UMH_WAIT_PROC) { | |
344 | call_usermodehelper_exec_sync(sub_info); | |
345 | } else { | |
346 | pid_t pid; | |
347 | /* | |
348 | * Use CLONE_PARENT to reparent it to kthreadd; we do not | |
349 | * want to pollute current->children, and we need a parent | |
350 | * that always ignores SIGCHLD to ensure auto-reaping. | |
351 | */ | |
352 | pid = kernel_thread(call_usermodehelper_exec_async, sub_info, | |
353 | CLONE_PARENT | SIGCHLD); | |
354 | if (pid < 0) { | |
355 | sub_info->retval = pid; | |
356 | umh_complete(sub_info); | |
357 | } | |
358 | } | |
359 | } | |
360 | ||
361 | /* | |
362 | * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY | |
363 | * (used for preventing user land processes from being created after the user | |
364 | * land has been frozen during a system-wide hibernation or suspend operation). | |
365 | * Should always be manipulated under umhelper_sem acquired for write. | |
366 | */ | |
367 | static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED; | |
368 | ||
369 | /* Number of helpers running */ | |
370 | static atomic_t running_helpers = ATOMIC_INIT(0); | |
371 | ||
372 | /* | |
373 | * Wait queue head used by usermodehelper_disable() to wait for all running | |
374 | * helpers to finish. | |
375 | */ | |
376 | static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); | |
377 | ||
378 | /* | |
379 | * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled | |
380 | * to become 'false'. | |
381 | */ | |
382 | static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq); | |
383 | ||
384 | /* | |
385 | * Time to wait for running_helpers to become zero before the setting of | |
386 | * usermodehelper_disabled in usermodehelper_disable() fails | |
387 | */ | |
388 | #define RUNNING_HELPERS_TIMEOUT (5 * HZ) | |
389 | ||
390 | int usermodehelper_read_trylock(void) | |
391 | { | |
392 | DEFINE_WAIT(wait); | |
393 | int ret = 0; | |
394 | ||
395 | down_read(&umhelper_sem); | |
396 | for (;;) { | |
397 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
398 | TASK_INTERRUPTIBLE); | |
399 | if (!usermodehelper_disabled) | |
400 | break; | |
401 | ||
402 | if (usermodehelper_disabled == UMH_DISABLED) | |
403 | ret = -EAGAIN; | |
404 | ||
405 | up_read(&umhelper_sem); | |
406 | ||
407 | if (ret) | |
408 | break; | |
409 | ||
410 | schedule(); | |
411 | try_to_freeze(); | |
412 | ||
413 | down_read(&umhelper_sem); | |
414 | } | |
415 | finish_wait(&usermodehelper_disabled_waitq, &wait); | |
416 | return ret; | |
417 | } | |
418 | EXPORT_SYMBOL_GPL(usermodehelper_read_trylock); | |
419 | ||
420 | long usermodehelper_read_lock_wait(long timeout) | |
421 | { | |
422 | DEFINE_WAIT(wait); | |
423 | ||
424 | if (timeout < 0) | |
425 | return -EINVAL; | |
426 | ||
427 | down_read(&umhelper_sem); | |
428 | for (;;) { | |
429 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
430 | TASK_UNINTERRUPTIBLE); | |
431 | if (!usermodehelper_disabled) | |
432 | break; | |
433 | ||
434 | up_read(&umhelper_sem); | |
435 | ||
436 | timeout = schedule_timeout(timeout); | |
437 | if (!timeout) | |
438 | break; | |
439 | ||
440 | down_read(&umhelper_sem); | |
441 | } | |
442 | finish_wait(&usermodehelper_disabled_waitq, &wait); | |
443 | return timeout; | |
444 | } | |
445 | EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait); | |
446 | ||
447 | void usermodehelper_read_unlock(void) | |
448 | { | |
449 | up_read(&umhelper_sem); | |
450 | } | |
451 | EXPORT_SYMBOL_GPL(usermodehelper_read_unlock); | |
452 | ||
453 | /** | |
454 | * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled. | |
455 | * @depth: New value to assign to usermodehelper_disabled. | |
456 | * | |
457 | * Change the value of usermodehelper_disabled (under umhelper_sem locked for | |
458 | * writing) and wakeup tasks waiting for it to change. | |
459 | */ | |
460 | void __usermodehelper_set_disable_depth(enum umh_disable_depth depth) | |
461 | { | |
462 | down_write(&umhelper_sem); | |
463 | usermodehelper_disabled = depth; | |
464 | wake_up(&usermodehelper_disabled_waitq); | |
465 | up_write(&umhelper_sem); | |
466 | } | |
467 | ||
468 | /** | |
469 | * __usermodehelper_disable - Prevent new helpers from being started. | |
470 | * @depth: New value to assign to usermodehelper_disabled. | |
471 | * | |
472 | * Set usermodehelper_disabled to @depth and wait for running helpers to exit. | |
473 | */ | |
474 | int __usermodehelper_disable(enum umh_disable_depth depth) | |
475 | { | |
476 | long retval; | |
477 | ||
478 | if (!depth) | |
479 | return -EINVAL; | |
480 | ||
481 | down_write(&umhelper_sem); | |
482 | usermodehelper_disabled = depth; | |
483 | up_write(&umhelper_sem); | |
484 | ||
485 | /* | |
486 | * From now on call_usermodehelper_exec() won't start any new | |
487 | * helpers, so it is sufficient if running_helpers turns out to | |
488 | * be zero at one point (it may be increased later, but that | |
489 | * doesn't matter). | |
490 | */ | |
491 | retval = wait_event_timeout(running_helpers_waitq, | |
492 | atomic_read(&running_helpers) == 0, | |
493 | RUNNING_HELPERS_TIMEOUT); | |
494 | if (retval) | |
495 | return 0; | |
496 | ||
497 | __usermodehelper_set_disable_depth(UMH_ENABLED); | |
498 | return -EAGAIN; | |
499 | } | |
500 | ||
501 | static void helper_lock(void) | |
502 | { | |
503 | atomic_inc(&running_helpers); | |
504 | smp_mb__after_atomic(); | |
505 | } | |
506 | ||
507 | static void helper_unlock(void) | |
508 | { | |
509 | if (atomic_dec_and_test(&running_helpers)) | |
510 | wake_up(&running_helpers_waitq); | |
511 | } | |
512 | ||
513 | /** | |
514 | * call_usermodehelper_setup - prepare to call a usermode helper | |
515 | * @path: path to usermode executable | |
516 | * @argv: arg vector for process | |
517 | * @envp: environment for process | |
518 | * @gfp_mask: gfp mask for memory allocation | |
519 | * @cleanup: a cleanup function | |
520 | * @init: an init function | |
521 | * @data: arbitrary context sensitive data | |
522 | * | |
523 | * Returns either %NULL on allocation failure, or a subprocess_info | |
524 | * structure. This should be passed to call_usermodehelper_exec to | |
525 | * exec the process and free the structure. | |
526 | * | |
527 | * The init function is used to customize the helper process prior to | |
528 | * exec. A non-zero return code causes the process to error out, exit, | |
529 | * and return the failure to the calling process | |
530 | * | |
531 | * The cleanup function is just before ethe subprocess_info is about to | |
532 | * be freed. This can be used for freeing the argv and envp. The | |
533 | * Function must be runnable in either a process context or the | |
534 | * context in which call_usermodehelper_exec is called. | |
535 | */ | |
536 | struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv, | |
537 | char **envp, gfp_t gfp_mask, | |
538 | int (*init)(struct subprocess_info *info, struct cred *new), | |
539 | void (*cleanup)(struct subprocess_info *info), | |
540 | void *data) | |
541 | { | |
542 | struct subprocess_info *sub_info; | |
543 | sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask); | |
544 | if (!sub_info) | |
545 | goto out; | |
546 | ||
547 | INIT_WORK(&sub_info->work, call_usermodehelper_exec_work); | |
548 | ||
549 | #ifdef CONFIG_STATIC_USERMODEHELPER | |
550 | sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH; | |
551 | #else | |
552 | sub_info->path = path; | |
553 | #endif | |
554 | sub_info->argv = argv; | |
555 | sub_info->envp = envp; | |
556 | ||
557 | sub_info->cleanup = cleanup; | |
558 | sub_info->init = init; | |
559 | sub_info->data = data; | |
560 | out: | |
561 | return sub_info; | |
562 | } | |
563 | EXPORT_SYMBOL(call_usermodehelper_setup); | |
564 | ||
565 | /** | |
566 | * call_usermodehelper_exec - start a usermode application | |
567 | * @sub_info: information about the subprocessa | |
568 | * @wait: wait for the application to finish and return status. | |
569 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back | |
570 | * when the program couldn't be exec'ed. This makes it safe to call | |
571 | * from interrupt context. | |
572 | * | |
573 | * Runs a user-space application. The application is started | |
574 | * asynchronously if wait is not set, and runs as a child of system workqueues. | |
575 | * (ie. it runs with full root capabilities and optimized affinity). | |
576 | */ | |
577 | int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) | |
578 | { | |
579 | DECLARE_COMPLETION_ONSTACK(done); | |
580 | int retval = 0; | |
581 | ||
582 | if (!sub_info->path) { | |
583 | call_usermodehelper_freeinfo(sub_info); | |
584 | return -EINVAL; | |
585 | } | |
586 | helper_lock(); | |
587 | if (usermodehelper_disabled) { | |
588 | retval = -EBUSY; | |
589 | goto out; | |
590 | } | |
591 | ||
592 | /* | |
593 | * If there is no binary for us to call, then just return and get out of | |
594 | * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and | |
595 | * disable all call_usermodehelper() calls. | |
596 | */ | |
597 | if (strlen(sub_info->path) == 0) | |
598 | goto out; | |
599 | ||
600 | /* | |
601 | * Set the completion pointer only if there is a waiter. | |
602 | * This makes it possible to use umh_complete to free | |
603 | * the data structure in case of UMH_NO_WAIT. | |
604 | */ | |
605 | sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done; | |
606 | sub_info->wait = wait; | |
607 | ||
608 | queue_work(system_unbound_wq, &sub_info->work); | |
609 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ | |
610 | goto unlock; | |
611 | ||
612 | if (wait & UMH_KILLABLE) { | |
613 | retval = wait_for_completion_killable(&done); | |
614 | if (!retval) | |
615 | goto wait_done; | |
616 | ||
617 | /* umh_complete() will see NULL and free sub_info */ | |
618 | if (xchg(&sub_info->complete, NULL)) | |
619 | goto unlock; | |
620 | /* fallthrough, umh_complete() was already called */ | |
621 | } | |
622 | ||
623 | wait_for_completion(&done); | |
624 | wait_done: | |
625 | retval = sub_info->retval; | |
626 | out: | |
627 | call_usermodehelper_freeinfo(sub_info); | |
628 | unlock: | |
629 | helper_unlock(); | |
630 | return retval; | |
631 | } | |
632 | EXPORT_SYMBOL(call_usermodehelper_exec); | |
633 | ||
634 | /** | |
635 | * call_usermodehelper() - prepare and start a usermode application | |
636 | * @path: path to usermode executable | |
637 | * @argv: arg vector for process | |
638 | * @envp: environment for process | |
639 | * @wait: wait for the application to finish and return status. | |
640 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back | |
641 | * when the program couldn't be exec'ed. This makes it safe to call | |
642 | * from interrupt context. | |
643 | * | |
644 | * This function is the equivalent to use call_usermodehelper_setup() and | |
645 | * call_usermodehelper_exec(). | |
646 | */ | |
647 | int call_usermodehelper(const char *path, char **argv, char **envp, int wait) | |
648 | { | |
649 | struct subprocess_info *info; | |
650 | gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL; | |
651 | ||
652 | info = call_usermodehelper_setup(path, argv, envp, gfp_mask, | |
653 | NULL, NULL, NULL); | |
654 | if (info == NULL) | |
655 | return -ENOMEM; | |
656 | ||
657 | return call_usermodehelper_exec(info, wait); | |
658 | } | |
659 | EXPORT_SYMBOL(call_usermodehelper); | |
660 | ||
661 | static int proc_cap_handler(struct ctl_table *table, int write, | |
662 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
663 | { | |
664 | struct ctl_table t; | |
665 | unsigned long cap_array[_KERNEL_CAPABILITY_U32S]; | |
666 | kernel_cap_t new_cap; | |
667 | int err, i; | |
668 | ||
669 | if (write && (!capable(CAP_SETPCAP) || | |
670 | !capable(CAP_SYS_MODULE))) | |
671 | return -EPERM; | |
672 | ||
673 | /* | |
674 | * convert from the global kernel_cap_t to the ulong array to print to | |
675 | * userspace if this is a read. | |
676 | */ | |
677 | spin_lock(&umh_sysctl_lock); | |
678 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) { | |
679 | if (table->data == CAP_BSET) | |
680 | cap_array[i] = usermodehelper_bset.cap[i]; | |
681 | else if (table->data == CAP_PI) | |
682 | cap_array[i] = usermodehelper_inheritable.cap[i]; | |
683 | else | |
684 | BUG(); | |
685 | } | |
686 | spin_unlock(&umh_sysctl_lock); | |
687 | ||
688 | t = *table; | |
689 | t.data = &cap_array; | |
690 | ||
691 | /* | |
692 | * actually read or write and array of ulongs from userspace. Remember | |
693 | * these are least significant 32 bits first | |
694 | */ | |
695 | err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); | |
696 | if (err < 0) | |
697 | return err; | |
698 | ||
699 | /* | |
700 | * convert from the sysctl array of ulongs to the kernel_cap_t | |
701 | * internal representation | |
702 | */ | |
703 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) | |
704 | new_cap.cap[i] = cap_array[i]; | |
705 | ||
706 | /* | |
707 | * Drop everything not in the new_cap (but don't add things) | |
708 | */ | |
709 | spin_lock(&umh_sysctl_lock); | |
710 | if (write) { | |
711 | if (table->data == CAP_BSET) | |
712 | usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap); | |
713 | if (table->data == CAP_PI) | |
714 | usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap); | |
715 | } | |
716 | spin_unlock(&umh_sysctl_lock); | |
717 | ||
718 | return 0; | |
719 | } | |
720 | ||
721 | struct ctl_table usermodehelper_table[] = { | |
722 | { | |
723 | .procname = "bset", | |
724 | .data = CAP_BSET, | |
725 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
726 | .mode = 0600, | |
727 | .proc_handler = proc_cap_handler, | |
728 | }, | |
729 | { | |
730 | .procname = "inheritable", | |
731 | .data = CAP_PI, | |
732 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
733 | .mode = 0600, | |
734 | .proc_handler = proc_cap_handler, | |
735 | }, | |
736 | { } | |
737 | }; |