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Commit | Line | Data |
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1da177e4 LT |
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 | */ | |
1da177e4 LT |
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> | |
1da177e4 | 26 | #include <linux/slab.h> |
1da177e4 | 27 | #include <linux/completion.h> |
17f60a7d | 28 | #include <linux/cred.h> |
1da177e4 | 29 | #include <linux/file.h> |
9f3acc31 | 30 | #include <linux/fdtable.h> |
1da177e4 LT |
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> | |
d025c9db | 36 | #include <linux/resource.h> |
8cdd4936 RW |
37 | #include <linux/notifier.h> |
38 | #include <linux/suspend.h> | |
b298d289 | 39 | #include <linux/rwsem.h> |
a74fb73c | 40 | #include <linux/ptrace.h> |
0fdff3ec | 41 | #include <linux/async.h> |
1da177e4 LT |
42 | #include <asm/uaccess.h> |
43 | ||
7ead8b83 LZ |
44 | #include <trace/events/module.h> |
45 | ||
1da177e4 LT |
46 | extern int max_threads; |
47 | ||
48 | static struct workqueue_struct *khelper_wq; | |
49 | ||
0f20784d TH |
50 | /* |
51 | * kmod_thread_locker is used for deadlock avoidance. There is no explicit | |
52 | * locking to protect this global - it is private to the singleton khelper | |
53 | * thread and should only ever be modified by that thread. | |
54 | */ | |
55 | static const struct task_struct *kmod_thread_locker; | |
56 | ||
17f60a7d EP |
57 | #define CAP_BSET (void *)1 |
58 | #define CAP_PI (void *)2 | |
59 | ||
60 | static kernel_cap_t usermodehelper_bset = CAP_FULL_SET; | |
61 | static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET; | |
62 | static DEFINE_SPINLOCK(umh_sysctl_lock); | |
b298d289 | 63 | static DECLARE_RWSEM(umhelper_sem); |
17f60a7d | 64 | |
a1ef5adb | 65 | #ifdef CONFIG_MODULES |
1da177e4 LT |
66 | |
67 | /* | |
68 | modprobe_path is set via /proc/sys. | |
69 | */ | |
70 | char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe"; | |
71 | ||
1cc684ab ON |
72 | static void free_modprobe_argv(struct subprocess_info *info) |
73 | { | |
74 | kfree(info->argv[3]); /* check call_modprobe() */ | |
75 | kfree(info->argv); | |
76 | } | |
77 | ||
3e63a93b ON |
78 | static int call_modprobe(char *module_name, int wait) |
79 | { | |
f634460c | 80 | struct subprocess_info *info; |
3e63a93b ON |
81 | static char *envp[] = { |
82 | "HOME=/", | |
83 | "TERM=linux", | |
84 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
85 | NULL | |
86 | }; | |
87 | ||
1cc684ab ON |
88 | char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL); |
89 | if (!argv) | |
90 | goto out; | |
91 | ||
92 | module_name = kstrdup(module_name, GFP_KERNEL); | |
93 | if (!module_name) | |
94 | goto free_argv; | |
95 | ||
96 | argv[0] = modprobe_path; | |
97 | argv[1] = "-q"; | |
98 | argv[2] = "--"; | |
99 | argv[3] = module_name; /* check free_modprobe_argv() */ | |
100 | argv[4] = NULL; | |
3e63a93b | 101 | |
f634460c LDM |
102 | info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL, |
103 | NULL, free_modprobe_argv, NULL); | |
104 | if (!info) | |
105 | goto free_module_name; | |
106 | ||
107 | return call_usermodehelper_exec(info, wait | UMH_KILLABLE); | |
108 | ||
109 | free_module_name: | |
110 | kfree(module_name); | |
1cc684ab ON |
111 | free_argv: |
112 | kfree(argv); | |
113 | out: | |
114 | return -ENOMEM; | |
3e63a93b ON |
115 | } |
116 | ||
1da177e4 | 117 | /** |
acae0515 AV |
118 | * __request_module - try to load a kernel module |
119 | * @wait: wait (or not) for the operation to complete | |
bd4207c9 RD |
120 | * @fmt: printf style format string for the name of the module |
121 | * @...: arguments as specified in the format string | |
1da177e4 LT |
122 | * |
123 | * Load a module using the user mode module loader. The function returns | |
124 | * zero on success or a negative errno code on failure. Note that a | |
125 | * successful module load does not mean the module did not then unload | |
126 | * and exit on an error of its own. Callers must check that the service | |
127 | * they requested is now available not blindly invoke it. | |
128 | * | |
129 | * If module auto-loading support is disabled then this function | |
130 | * becomes a no-operation. | |
131 | */ | |
acae0515 | 132 | int __request_module(bool wait, const char *fmt, ...) |
1da177e4 LT |
133 | { |
134 | va_list args; | |
135 | char module_name[MODULE_NAME_LEN]; | |
136 | unsigned int max_modprobes; | |
137 | int ret; | |
1da177e4 LT |
138 | static atomic_t kmod_concurrent = ATOMIC_INIT(0); |
139 | #define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */ | |
140 | static int kmod_loop_msg; | |
141 | ||
0fdff3ec TH |
142 | /* |
143 | * We don't allow synchronous module loading from async. Module | |
144 | * init may invoke async_synchronize_full() which will end up | |
145 | * waiting for this task which already is waiting for the module | |
146 | * loading to complete, leading to a deadlock. | |
147 | */ | |
148 | WARN_ON_ONCE(wait && current_is_async()); | |
149 | ||
7f57cfa4 ON |
150 | if (!modprobe_path[0]) |
151 | return 0; | |
152 | ||
1da177e4 LT |
153 | va_start(args, fmt); |
154 | ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args); | |
155 | va_end(args); | |
156 | if (ret >= MODULE_NAME_LEN) | |
157 | return -ENAMETOOLONG; | |
158 | ||
dd8dbf2e EP |
159 | ret = security_kernel_module_request(module_name); |
160 | if (ret) | |
161 | return ret; | |
162 | ||
1da177e4 LT |
163 | /* If modprobe needs a service that is in a module, we get a recursive |
164 | * loop. Limit the number of running kmod threads to max_threads/2 or | |
165 | * MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method | |
166 | * would be to run the parents of this process, counting how many times | |
167 | * kmod was invoked. That would mean accessing the internals of the | |
168 | * process tables to get the command line, proc_pid_cmdline is static | |
169 | * and it is not worth changing the proc code just to handle this case. | |
170 | * KAO. | |
171 | * | |
172 | * "trace the ppid" is simple, but will fail if someone's | |
173 | * parent exits. I think this is as good as it gets. --RR | |
174 | */ | |
175 | max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT); | |
176 | atomic_inc(&kmod_concurrent); | |
177 | if (atomic_read(&kmod_concurrent) > max_modprobes) { | |
178 | /* We may be blaming an innocent here, but unlikely */ | |
37252db6 | 179 | if (kmod_loop_msg < 5) { |
1da177e4 LT |
180 | printk(KERN_ERR |
181 | "request_module: runaway loop modprobe %s\n", | |
182 | module_name); | |
37252db6 JK |
183 | kmod_loop_msg++; |
184 | } | |
1da177e4 LT |
185 | atomic_dec(&kmod_concurrent); |
186 | return -ENOMEM; | |
187 | } | |
188 | ||
7ead8b83 LZ |
189 | trace_module_request(module_name, wait, _RET_IP_); |
190 | ||
3e63a93b | 191 | ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC); |
a06a4dc3 | 192 | |
1da177e4 LT |
193 | atomic_dec(&kmod_concurrent); |
194 | return ret; | |
195 | } | |
acae0515 | 196 | EXPORT_SYMBOL(__request_module); |
118a9069 | 197 | #endif /* CONFIG_MODULES */ |
1da177e4 | 198 | |
0baf2a4d MS |
199 | static void call_usermodehelper_freeinfo(struct subprocess_info *info) |
200 | { | |
201 | if (info->cleanup) | |
202 | (*info->cleanup)(info); | |
203 | kfree(info); | |
204 | } | |
205 | ||
206 | static void umh_complete(struct subprocess_info *sub_info) | |
207 | { | |
208 | struct completion *comp = xchg(&sub_info->complete, NULL); | |
209 | /* | |
210 | * See call_usermodehelper_exec(). If xchg() returns NULL | |
211 | * we own sub_info, the UMH_KILLABLE caller has gone away | |
212 | * or the caller used UMH_NO_WAIT. | |
213 | */ | |
214 | if (comp) | |
215 | complete(comp); | |
216 | else | |
217 | call_usermodehelper_freeinfo(sub_info); | |
218 | } | |
219 | ||
1da177e4 LT |
220 | /* |
221 | * This is the task which runs the usermode application | |
222 | */ | |
223 | static int ____call_usermodehelper(void *data) | |
224 | { | |
225 | struct subprocess_info *sub_info = data; | |
0baf2a4d | 226 | int wait = sub_info->wait & ~UMH_KILLABLE; |
17f60a7d | 227 | struct cred *new; |
1da177e4 LT |
228 | int retval; |
229 | ||
1da177e4 LT |
230 | spin_lock_irq(¤t->sighand->siglock); |
231 | flush_signal_handlers(current, 1); | |
1da177e4 LT |
232 | spin_unlock_irq(¤t->sighand->siglock); |
233 | ||
234 | /* We can run anywhere, unlike our parent keventd(). */ | |
1a2142af | 235 | set_cpus_allowed_ptr(current, cpu_all_mask); |
1da177e4 | 236 | |
b73a7e76 JE |
237 | /* |
238 | * Our parent is keventd, which runs with elevated scheduling priority. | |
239 | * Avoid propagating that into the userspace child. | |
240 | */ | |
241 | set_user_nice(current, 0); | |
242 | ||
17f60a7d EP |
243 | retval = -ENOMEM; |
244 | new = prepare_kernel_cred(current); | |
245 | if (!new) | |
0baf2a4d | 246 | goto out; |
17f60a7d EP |
247 | |
248 | spin_lock(&umh_sysctl_lock); | |
249 | new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset); | |
250 | new->cap_inheritable = cap_intersect(usermodehelper_inheritable, | |
251 | new->cap_inheritable); | |
252 | spin_unlock(&umh_sysctl_lock); | |
253 | ||
87966996 DH |
254 | if (sub_info->init) { |
255 | retval = sub_info->init(sub_info, new); | |
256 | if (retval) { | |
257 | abort_creds(new); | |
0baf2a4d | 258 | goto out; |
87966996 DH |
259 | } |
260 | } | |
261 | ||
17f60a7d EP |
262 | commit_creds(new); |
263 | ||
c4ad8f98 | 264 | retval = do_execve(getname_kernel(sub_info->path), |
ae903caa AV |
265 | (const char __user *const __user *)sub_info->argv, |
266 | (const char __user *const __user *)sub_info->envp); | |
0baf2a4d MS |
267 | out: |
268 | sub_info->retval = retval; | |
269 | /* wait_for_helper() will call umh_complete if UHM_WAIT_PROC. */ | |
270 | if (wait != UMH_WAIT_PROC) | |
271 | umh_complete(sub_info); | |
a74fb73c AV |
272 | if (!retval) |
273 | return 0; | |
fb45550d | 274 | do_exit(0); |
1da177e4 LT |
275 | } |
276 | ||
0f20784d TH |
277 | static int call_helper(void *data) |
278 | { | |
279 | /* Worker thread started blocking khelper thread. */ | |
280 | kmod_thread_locker = current; | |
281 | return ____call_usermodehelper(data); | |
282 | } | |
283 | ||
1da177e4 LT |
284 | /* Keventd can't block, but this (a child) can. */ |
285 | static int wait_for_helper(void *data) | |
286 | { | |
287 | struct subprocess_info *sub_info = data; | |
288 | pid_t pid; | |
1da177e4 | 289 | |
7d642242 | 290 | /* If SIGCLD is ignored sys_wait4 won't populate the status. */ |
76e0a6f4 | 291 | kernel_sigaction(SIGCHLD, SIG_DFL); |
1da177e4 LT |
292 | pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD); |
293 | if (pid < 0) { | |
294 | sub_info->retval = pid; | |
295 | } else { | |
7d642242 | 296 | int ret = -ECHILD; |
1da177e4 LT |
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 wait_for_helper() always runs as keventd, and put_user() | |
301 | * to a kernel address works OK for kernel threads, due to their | |
302 | * having an mm_segment_t which spans the entire address space. | |
303 | * | |
304 | * Thus the __user pointer cast is valid here. | |
305 | */ | |
111dbe0c BS |
306 | sys_wait4(pid, (int __user *)&ret, 0, NULL); |
307 | ||
308 | /* | |
309 | * If ret is 0, either ____call_usermodehelper failed and the | |
310 | * real error code is already in sub_info->retval or | |
311 | * sub_info->retval is 0 anyway, so don't mess with it then. | |
312 | */ | |
313 | if (ret) | |
314 | sub_info->retval = ret; | |
1da177e4 LT |
315 | } |
316 | ||
b3449922 | 317 | umh_complete(sub_info); |
fb45550d | 318 | do_exit(0); |
1da177e4 LT |
319 | } |
320 | ||
321 | /* This is run by khelper thread */ | |
65f27f38 | 322 | static void __call_usermodehelper(struct work_struct *work) |
1da177e4 | 323 | { |
65f27f38 DH |
324 | struct subprocess_info *sub_info = |
325 | container_of(work, struct subprocess_info, work); | |
9d944ef3 | 326 | int wait = sub_info->wait & ~UMH_KILLABLE; |
d47419cd | 327 | pid_t pid; |
1da177e4 LT |
328 | |
329 | /* CLONE_VFORK: wait until the usermode helper has execve'd | |
330 | * successfully We need the data structures to stay around | |
331 | * until that is done. */ | |
d47419cd | 332 | if (wait == UMH_WAIT_PROC) |
1da177e4 LT |
333 | pid = kernel_thread(wait_for_helper, sub_info, |
334 | CLONE_FS | CLONE_FILES | SIGCHLD); | |
0f20784d TH |
335 | else { |
336 | pid = kernel_thread(call_helper, sub_info, | |
1da177e4 | 337 | CLONE_VFORK | SIGCHLD); |
0f20784d TH |
338 | /* Worker thread stopped blocking khelper thread. */ |
339 | kmod_thread_locker = NULL; | |
340 | } | |
1da177e4 | 341 | |
0baf2a4d MS |
342 | if (pid < 0) { |
343 | sub_info->retval = pid; | |
b3449922 | 344 | umh_complete(sub_info); |
86313c48 | 345 | } |
1da177e4 LT |
346 | } |
347 | ||
ccd4b65a RW |
348 | /* |
349 | * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY | |
350 | * (used for preventing user land processes from being created after the user | |
351 | * land has been frozen during a system-wide hibernation or suspend operation). | |
b298d289 | 352 | * Should always be manipulated under umhelper_sem acquired for write. |
ccd4b65a | 353 | */ |
247bc037 | 354 | static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED; |
ccd4b65a RW |
355 | |
356 | /* Number of helpers running */ | |
357 | static atomic_t running_helpers = ATOMIC_INIT(0); | |
358 | ||
359 | /* | |
5307427a | 360 | * Wait queue head used by usermodehelper_disable() to wait for all running |
ccd4b65a RW |
361 | * helpers to finish. |
362 | */ | |
363 | static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); | |
364 | ||
9b78c1da RW |
365 | /* |
366 | * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled | |
367 | * to become 'false'. | |
368 | */ | |
369 | static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq); | |
370 | ||
ccd4b65a RW |
371 | /* |
372 | * Time to wait for running_helpers to become zero before the setting of | |
5307427a | 373 | * usermodehelper_disabled in usermodehelper_disable() fails |
ccd4b65a RW |
374 | */ |
375 | #define RUNNING_HELPERS_TIMEOUT (5 * HZ) | |
376 | ||
fe2e39d8 | 377 | int usermodehelper_read_trylock(void) |
b298d289 | 378 | { |
247bc037 | 379 | DEFINE_WAIT(wait); |
fe2e39d8 RW |
380 | int ret = 0; |
381 | ||
b298d289 | 382 | down_read(&umhelper_sem); |
247bc037 RW |
383 | for (;;) { |
384 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
385 | TASK_INTERRUPTIBLE); | |
386 | if (!usermodehelper_disabled) | |
387 | break; | |
388 | ||
389 | if (usermodehelper_disabled == UMH_DISABLED) | |
390 | ret = -EAGAIN; | |
391 | ||
fe2e39d8 | 392 | up_read(&umhelper_sem); |
247bc037 RW |
393 | |
394 | if (ret) | |
395 | break; | |
396 | ||
397 | schedule(); | |
398 | try_to_freeze(); | |
399 | ||
400 | down_read(&umhelper_sem); | |
fe2e39d8 | 401 | } |
247bc037 | 402 | finish_wait(&usermodehelper_disabled_waitq, &wait); |
fe2e39d8 | 403 | return ret; |
b298d289 | 404 | } |
fe2e39d8 | 405 | EXPORT_SYMBOL_GPL(usermodehelper_read_trylock); |
b298d289 | 406 | |
9b78c1da RW |
407 | long usermodehelper_read_lock_wait(long timeout) |
408 | { | |
409 | DEFINE_WAIT(wait); | |
410 | ||
411 | if (timeout < 0) | |
412 | return -EINVAL; | |
413 | ||
414 | down_read(&umhelper_sem); | |
415 | for (;;) { | |
416 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
417 | TASK_UNINTERRUPTIBLE); | |
418 | if (!usermodehelper_disabled) | |
419 | break; | |
420 | ||
421 | up_read(&umhelper_sem); | |
422 | ||
423 | timeout = schedule_timeout(timeout); | |
424 | if (!timeout) | |
425 | break; | |
426 | ||
427 | down_read(&umhelper_sem); | |
428 | } | |
429 | finish_wait(&usermodehelper_disabled_waitq, &wait); | |
430 | return timeout; | |
431 | } | |
432 | EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait); | |
433 | ||
fe2e39d8 | 434 | void usermodehelper_read_unlock(void) |
b298d289 SB |
435 | { |
436 | up_read(&umhelper_sem); | |
437 | } | |
fe2e39d8 | 438 | EXPORT_SYMBOL_GPL(usermodehelper_read_unlock); |
b298d289 | 439 | |
9b78c1da | 440 | /** |
247bc037 | 441 | * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled. |
9b3c98cd | 442 | * @depth: New value to assign to usermodehelper_disabled. |
247bc037 RW |
443 | * |
444 | * Change the value of usermodehelper_disabled (under umhelper_sem locked for | |
445 | * writing) and wakeup tasks waiting for it to change. | |
9b78c1da | 446 | */ |
247bc037 | 447 | void __usermodehelper_set_disable_depth(enum umh_disable_depth depth) |
9b78c1da RW |
448 | { |
449 | down_write(&umhelper_sem); | |
247bc037 | 450 | usermodehelper_disabled = depth; |
9b78c1da RW |
451 | wake_up(&usermodehelper_disabled_waitq); |
452 | up_write(&umhelper_sem); | |
453 | } | |
454 | ||
1bfcf130 | 455 | /** |
247bc037 RW |
456 | * __usermodehelper_disable - Prevent new helpers from being started. |
457 | * @depth: New value to assign to usermodehelper_disabled. | |
458 | * | |
459 | * Set usermodehelper_disabled to @depth and wait for running helpers to exit. | |
1bfcf130 | 460 | */ |
247bc037 | 461 | int __usermodehelper_disable(enum umh_disable_depth depth) |
8cdd4936 | 462 | { |
ccd4b65a RW |
463 | long retval; |
464 | ||
247bc037 RW |
465 | if (!depth) |
466 | return -EINVAL; | |
467 | ||
b298d289 | 468 | down_write(&umhelper_sem); |
247bc037 | 469 | usermodehelper_disabled = depth; |
b298d289 SB |
470 | up_write(&umhelper_sem); |
471 | ||
1bfcf130 RW |
472 | /* |
473 | * From now on call_usermodehelper_exec() won't start any new | |
474 | * helpers, so it is sufficient if running_helpers turns out to | |
475 | * be zero at one point (it may be increased later, but that | |
476 | * doesn't matter). | |
477 | */ | |
478 | retval = wait_event_timeout(running_helpers_waitq, | |
ccd4b65a RW |
479 | atomic_read(&running_helpers) == 0, |
480 | RUNNING_HELPERS_TIMEOUT); | |
1bfcf130 RW |
481 | if (retval) |
482 | return 0; | |
8cdd4936 | 483 | |
247bc037 | 484 | __usermodehelper_set_disable_depth(UMH_ENABLED); |
1bfcf130 RW |
485 | return -EAGAIN; |
486 | } | |
487 | ||
ccd4b65a RW |
488 | static void helper_lock(void) |
489 | { | |
490 | atomic_inc(&running_helpers); | |
4e857c58 | 491 | smp_mb__after_atomic(); |
ccd4b65a RW |
492 | } |
493 | ||
494 | static void helper_unlock(void) | |
495 | { | |
496 | if (atomic_dec_and_test(&running_helpers)) | |
497 | wake_up(&running_helpers_waitq); | |
498 | } | |
ccd4b65a | 499 | |
1da177e4 | 500 | /** |
0ab4dc92 | 501 | * call_usermodehelper_setup - prepare to call a usermode helper |
61df47c8 RD |
502 | * @path: path to usermode executable |
503 | * @argv: arg vector for process | |
504 | * @envp: environment for process | |
ac331d15 | 505 | * @gfp_mask: gfp mask for memory allocation |
938e4b22 LDM |
506 | * @cleanup: a cleanup function |
507 | * @init: an init function | |
508 | * @data: arbitrary context sensitive data | |
0ab4dc92 | 509 | * |
61df47c8 | 510 | * Returns either %NULL on allocation failure, or a subprocess_info |
0ab4dc92 JF |
511 | * structure. This should be passed to call_usermodehelper_exec to |
512 | * exec the process and free the structure. | |
938e4b22 LDM |
513 | * |
514 | * The init function is used to customize the helper process prior to | |
515 | * exec. A non-zero return code causes the process to error out, exit, | |
516 | * and return the failure to the calling process | |
517 | * | |
518 | * The cleanup function is just before ethe subprocess_info is about to | |
519 | * be freed. This can be used for freeing the argv and envp. The | |
520 | * Function must be runnable in either a process context or the | |
521 | * context in which call_usermodehelper_exec is called. | |
0ab4dc92 | 522 | */ |
ac331d15 | 523 | struct subprocess_info *call_usermodehelper_setup(char *path, char **argv, |
938e4b22 LDM |
524 | char **envp, gfp_t gfp_mask, |
525 | int (*init)(struct subprocess_info *info, struct cred *new), | |
526 | void (*cleanup)(struct subprocess_info *info), | |
527 | void *data) | |
0ab4dc92 JF |
528 | { |
529 | struct subprocess_info *sub_info; | |
ac331d15 | 530 | sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask); |
0ab4dc92 JF |
531 | if (!sub_info) |
532 | goto out; | |
533 | ||
534 | INIT_WORK(&sub_info->work, __call_usermodehelper); | |
535 | sub_info->path = path; | |
536 | sub_info->argv = argv; | |
537 | sub_info->envp = envp; | |
938e4b22 LDM |
538 | |
539 | sub_info->cleanup = cleanup; | |
540 | sub_info->init = init; | |
541 | sub_info->data = data; | |
0ab4dc92 JF |
542 | out: |
543 | return sub_info; | |
544 | } | |
938e4b22 | 545 | EXPORT_SYMBOL(call_usermodehelper_setup); |
0ab4dc92 | 546 | |
0ab4dc92 JF |
547 | /** |
548 | * call_usermodehelper_exec - start a usermode application | |
549 | * @sub_info: information about the subprocessa | |
1da177e4 | 550 | * @wait: wait for the application to finish and return status. |
66e5b7e1 LDM |
551 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back |
552 | * when the program couldn't be exec'ed. This makes it safe to call | |
a98f0dd3 | 553 | * from interrupt context. |
1da177e4 LT |
554 | * |
555 | * Runs a user-space application. The application is started | |
556 | * asynchronously if wait is not set, and runs as a child of keventd. | |
557 | * (ie. it runs with full root capabilities). | |
1da177e4 | 558 | */ |
9d944ef3 | 559 | int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) |
1da177e4 | 560 | { |
60be6b9a | 561 | DECLARE_COMPLETION_ONSTACK(done); |
78468033 | 562 | int retval = 0; |
1da177e4 | 563 | |
4c1c7be9 TH |
564 | if (!sub_info->path) { |
565 | call_usermodehelper_freeinfo(sub_info); | |
566 | return -EINVAL; | |
567 | } | |
ccd4b65a | 568 | helper_lock(); |
8cdd4936 | 569 | if (!khelper_wq || usermodehelper_disabled) { |
0ab4dc92 JF |
570 | retval = -EBUSY; |
571 | goto out; | |
572 | } | |
0f20784d TH |
573 | /* |
574 | * Worker thread must not wait for khelper thread at below | |
575 | * wait_for_completion() if the thread was created with CLONE_VFORK | |
576 | * flag, for khelper thread is already waiting for the thread at | |
577 | * wait_for_completion() in do_fork(). | |
578 | */ | |
579 | if (wait != UMH_NO_WAIT && current == kmod_thread_locker) { | |
580 | retval = -EBUSY; | |
581 | goto out; | |
582 | } | |
a98f0dd3 | 583 | |
0baf2a4d MS |
584 | /* |
585 | * Set the completion pointer only if there is a waiter. | |
586 | * This makes it possible to use umh_complete to free | |
587 | * the data structure in case of UMH_NO_WAIT. | |
588 | */ | |
589 | sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done; | |
a98f0dd3 AK |
590 | sub_info->wait = wait; |
591 | ||
592 | queue_work(khelper_wq, &sub_info->work); | |
78468033 NC |
593 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ |
594 | goto unlock; | |
d0bd587a ON |
595 | |
596 | if (wait & UMH_KILLABLE) { | |
597 | retval = wait_for_completion_killable(&done); | |
598 | if (!retval) | |
599 | goto wait_done; | |
600 | ||
601 | /* umh_complete() will see NULL and free sub_info */ | |
602 | if (xchg(&sub_info->complete, NULL)) | |
603 | goto unlock; | |
604 | /* fallthrough, umh_complete() was already called */ | |
605 | } | |
606 | ||
1da177e4 | 607 | wait_for_completion(&done); |
d0bd587a | 608 | wait_done: |
a98f0dd3 | 609 | retval = sub_info->retval; |
78468033 | 610 | out: |
0ab4dc92 | 611 | call_usermodehelper_freeinfo(sub_info); |
78468033 | 612 | unlock: |
ccd4b65a | 613 | helper_unlock(); |
a98f0dd3 | 614 | return retval; |
1da177e4 | 615 | } |
938e4b22 | 616 | EXPORT_SYMBOL(call_usermodehelper_exec); |
785042f2 | 617 | |
66e5b7e1 LDM |
618 | /** |
619 | * call_usermodehelper() - prepare and start a usermode application | |
620 | * @path: path to usermode executable | |
621 | * @argv: arg vector for process | |
622 | * @envp: environment for process | |
623 | * @wait: wait for the application to finish and return status. | |
624 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back | |
625 | * when the program couldn't be exec'ed. This makes it safe to call | |
626 | * from interrupt context. | |
627 | * | |
628 | * This function is the equivalent to use call_usermodehelper_setup() and | |
629 | * call_usermodehelper_exec(). | |
79c743dd | 630 | */ |
66e5b7e1 | 631 | int call_usermodehelper(char *path, char **argv, char **envp, int wait) |
785042f2 BH |
632 | { |
633 | struct subprocess_info *info; | |
634 | gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL; | |
635 | ||
938e4b22 | 636 | info = call_usermodehelper_setup(path, argv, envp, gfp_mask, |
66e5b7e1 | 637 | NULL, NULL, NULL); |
785042f2 BH |
638 | if (info == NULL) |
639 | return -ENOMEM; | |
640 | ||
785042f2 BH |
641 | return call_usermodehelper_exec(info, wait); |
642 | } | |
66e5b7e1 | 643 | EXPORT_SYMBOL(call_usermodehelper); |
1da177e4 | 644 | |
17f60a7d EP |
645 | static int proc_cap_handler(struct ctl_table *table, int write, |
646 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
647 | { | |
648 | struct ctl_table t; | |
649 | unsigned long cap_array[_KERNEL_CAPABILITY_U32S]; | |
650 | kernel_cap_t new_cap; | |
651 | int err, i; | |
652 | ||
653 | if (write && (!capable(CAP_SETPCAP) || | |
654 | !capable(CAP_SYS_MODULE))) | |
655 | return -EPERM; | |
656 | ||
657 | /* | |
658 | * convert from the global kernel_cap_t to the ulong array to print to | |
659 | * userspace if this is a read. | |
660 | */ | |
661 | spin_lock(&umh_sysctl_lock); | |
662 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) { | |
663 | if (table->data == CAP_BSET) | |
664 | cap_array[i] = usermodehelper_bset.cap[i]; | |
665 | else if (table->data == CAP_PI) | |
666 | cap_array[i] = usermodehelper_inheritable.cap[i]; | |
667 | else | |
668 | BUG(); | |
669 | } | |
670 | spin_unlock(&umh_sysctl_lock); | |
671 | ||
672 | t = *table; | |
673 | t.data = &cap_array; | |
674 | ||
675 | /* | |
676 | * actually read or write and array of ulongs from userspace. Remember | |
677 | * these are least significant 32 bits first | |
678 | */ | |
679 | err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); | |
680 | if (err < 0) | |
681 | return err; | |
682 | ||
683 | /* | |
684 | * convert from the sysctl array of ulongs to the kernel_cap_t | |
685 | * internal representation | |
686 | */ | |
687 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) | |
688 | new_cap.cap[i] = cap_array[i]; | |
689 | ||
690 | /* | |
691 | * Drop everything not in the new_cap (but don't add things) | |
692 | */ | |
693 | spin_lock(&umh_sysctl_lock); | |
694 | if (write) { | |
695 | if (table->data == CAP_BSET) | |
696 | usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap); | |
697 | if (table->data == CAP_PI) | |
698 | usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap); | |
699 | } | |
700 | spin_unlock(&umh_sysctl_lock); | |
701 | ||
702 | return 0; | |
703 | } | |
704 | ||
705 | struct ctl_table usermodehelper_table[] = { | |
706 | { | |
707 | .procname = "bset", | |
708 | .data = CAP_BSET, | |
709 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
710 | .mode = 0600, | |
711 | .proc_handler = proc_cap_handler, | |
712 | }, | |
713 | { | |
714 | .procname = "inheritable", | |
715 | .data = CAP_PI, | |
716 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
717 | .mode = 0600, | |
718 | .proc_handler = proc_cap_handler, | |
719 | }, | |
720 | { } | |
721 | }; | |
722 | ||
1da177e4 LT |
723 | void __init usermodehelper_init(void) |
724 | { | |
725 | khelper_wq = create_singlethread_workqueue("khelper"); | |
726 | BUG_ON(!khelper_wq); | |
727 | } |