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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> |
1da177e4 LT |
40 | #include <asm/uaccess.h> |
41 | ||
7ead8b83 LZ |
42 | #include <trace/events/module.h> |
43 | ||
1da177e4 LT |
44 | extern int max_threads; |
45 | ||
46 | static struct workqueue_struct *khelper_wq; | |
47 | ||
0f20784d TH |
48 | /* |
49 | * kmod_thread_locker is used for deadlock avoidance. There is no explicit | |
50 | * locking to protect this global - it is private to the singleton khelper | |
51 | * thread and should only ever be modified by that thread. | |
52 | */ | |
53 | static const struct task_struct *kmod_thread_locker; | |
54 | ||
17f60a7d EP |
55 | #define CAP_BSET (void *)1 |
56 | #define CAP_PI (void *)2 | |
57 | ||
58 | static kernel_cap_t usermodehelper_bset = CAP_FULL_SET; | |
59 | static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET; | |
60 | static DEFINE_SPINLOCK(umh_sysctl_lock); | |
b298d289 | 61 | static DECLARE_RWSEM(umhelper_sem); |
17f60a7d | 62 | |
a1ef5adb | 63 | #ifdef CONFIG_MODULES |
1da177e4 LT |
64 | |
65 | /* | |
66 | modprobe_path is set via /proc/sys. | |
67 | */ | |
68 | char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe"; | |
69 | ||
1cc684ab ON |
70 | static void free_modprobe_argv(struct subprocess_info *info) |
71 | { | |
72 | kfree(info->argv[3]); /* check call_modprobe() */ | |
73 | kfree(info->argv); | |
74 | } | |
75 | ||
3e63a93b ON |
76 | static int call_modprobe(char *module_name, int wait) |
77 | { | |
78 | static char *envp[] = { | |
79 | "HOME=/", | |
80 | "TERM=linux", | |
81 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
82 | NULL | |
83 | }; | |
84 | ||
1cc684ab ON |
85 | char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL); |
86 | if (!argv) | |
87 | goto out; | |
88 | ||
89 | module_name = kstrdup(module_name, GFP_KERNEL); | |
90 | if (!module_name) | |
91 | goto free_argv; | |
92 | ||
93 | argv[0] = modprobe_path; | |
94 | argv[1] = "-q"; | |
95 | argv[2] = "--"; | |
96 | argv[3] = module_name; /* check free_modprobe_argv() */ | |
97 | argv[4] = NULL; | |
3e63a93b ON |
98 | |
99 | return call_usermodehelper_fns(modprobe_path, argv, envp, | |
1cc684ab ON |
100 | wait | UMH_KILLABLE, NULL, free_modprobe_argv, NULL); |
101 | free_argv: | |
102 | kfree(argv); | |
103 | out: | |
104 | return -ENOMEM; | |
3e63a93b ON |
105 | } |
106 | ||
1da177e4 | 107 | /** |
acae0515 AV |
108 | * __request_module - try to load a kernel module |
109 | * @wait: wait (or not) for the operation to complete | |
bd4207c9 RD |
110 | * @fmt: printf style format string for the name of the module |
111 | * @...: arguments as specified in the format string | |
1da177e4 LT |
112 | * |
113 | * Load a module using the user mode module loader. The function returns | |
114 | * zero on success or a negative errno code on failure. Note that a | |
115 | * successful module load does not mean the module did not then unload | |
116 | * and exit on an error of its own. Callers must check that the service | |
117 | * they requested is now available not blindly invoke it. | |
118 | * | |
119 | * If module auto-loading support is disabled then this function | |
120 | * becomes a no-operation. | |
121 | */ | |
acae0515 | 122 | int __request_module(bool wait, const char *fmt, ...) |
1da177e4 LT |
123 | { |
124 | va_list args; | |
125 | char module_name[MODULE_NAME_LEN]; | |
126 | unsigned int max_modprobes; | |
127 | int ret; | |
1da177e4 LT |
128 | static atomic_t kmod_concurrent = ATOMIC_INIT(0); |
129 | #define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */ | |
130 | static int kmod_loop_msg; | |
131 | ||
132 | va_start(args, fmt); | |
133 | ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args); | |
134 | va_end(args); | |
135 | if (ret >= MODULE_NAME_LEN) | |
136 | return -ENAMETOOLONG; | |
137 | ||
dd8dbf2e EP |
138 | ret = security_kernel_module_request(module_name); |
139 | if (ret) | |
140 | return ret; | |
141 | ||
1da177e4 LT |
142 | /* If modprobe needs a service that is in a module, we get a recursive |
143 | * loop. Limit the number of running kmod threads to max_threads/2 or | |
144 | * MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method | |
145 | * would be to run the parents of this process, counting how many times | |
146 | * kmod was invoked. That would mean accessing the internals of the | |
147 | * process tables to get the command line, proc_pid_cmdline is static | |
148 | * and it is not worth changing the proc code just to handle this case. | |
149 | * KAO. | |
150 | * | |
151 | * "trace the ppid" is simple, but will fail if someone's | |
152 | * parent exits. I think this is as good as it gets. --RR | |
153 | */ | |
154 | max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT); | |
155 | atomic_inc(&kmod_concurrent); | |
156 | if (atomic_read(&kmod_concurrent) > max_modprobes) { | |
157 | /* We may be blaming an innocent here, but unlikely */ | |
37252db6 | 158 | if (kmod_loop_msg < 5) { |
1da177e4 LT |
159 | printk(KERN_ERR |
160 | "request_module: runaway loop modprobe %s\n", | |
161 | module_name); | |
37252db6 JK |
162 | kmod_loop_msg++; |
163 | } | |
1da177e4 LT |
164 | atomic_dec(&kmod_concurrent); |
165 | return -ENOMEM; | |
166 | } | |
167 | ||
7ead8b83 LZ |
168 | trace_module_request(module_name, wait, _RET_IP_); |
169 | ||
3e63a93b | 170 | ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC); |
a06a4dc3 | 171 | |
1da177e4 LT |
172 | atomic_dec(&kmod_concurrent); |
173 | return ret; | |
174 | } | |
acae0515 | 175 | EXPORT_SYMBOL(__request_module); |
118a9069 | 176 | #endif /* CONFIG_MODULES */ |
1da177e4 | 177 | |
1da177e4 LT |
178 | /* |
179 | * This is the task which runs the usermode application | |
180 | */ | |
181 | static int ____call_usermodehelper(void *data) | |
182 | { | |
183 | struct subprocess_info *sub_info = data; | |
17f60a7d | 184 | struct cred *new; |
1da177e4 LT |
185 | int retval; |
186 | ||
1da177e4 LT |
187 | spin_lock_irq(¤t->sighand->siglock); |
188 | flush_signal_handlers(current, 1); | |
1da177e4 LT |
189 | spin_unlock_irq(¤t->sighand->siglock); |
190 | ||
191 | /* We can run anywhere, unlike our parent keventd(). */ | |
1a2142af | 192 | set_cpus_allowed_ptr(current, cpu_all_mask); |
1da177e4 | 193 | |
b73a7e76 JE |
194 | /* |
195 | * Our parent is keventd, which runs with elevated scheduling priority. | |
196 | * Avoid propagating that into the userspace child. | |
197 | */ | |
198 | set_user_nice(current, 0); | |
199 | ||
17f60a7d EP |
200 | retval = -ENOMEM; |
201 | new = prepare_kernel_cred(current); | |
202 | if (!new) | |
203 | goto fail; | |
204 | ||
205 | spin_lock(&umh_sysctl_lock); | |
206 | new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset); | |
207 | new->cap_inheritable = cap_intersect(usermodehelper_inheritable, | |
208 | new->cap_inheritable); | |
209 | spin_unlock(&umh_sysctl_lock); | |
210 | ||
87966996 DH |
211 | if (sub_info->init) { |
212 | retval = sub_info->init(sub_info, new); | |
213 | if (retval) { | |
214 | abort_creds(new); | |
215 | goto fail; | |
216 | } | |
217 | } | |
218 | ||
17f60a7d EP |
219 | commit_creds(new); |
220 | ||
d7627467 DH |
221 | retval = kernel_execve(sub_info->path, |
222 | (const char *const *)sub_info->argv, | |
223 | (const char *const *)sub_info->envp); | |
1da177e4 LT |
224 | |
225 | /* Exec failed? */ | |
a06a4dc3 | 226 | fail: |
1da177e4 | 227 | sub_info->retval = retval; |
5b9bd473 | 228 | return 0; |
1da177e4 LT |
229 | } |
230 | ||
0f20784d TH |
231 | static int call_helper(void *data) |
232 | { | |
233 | /* Worker thread started blocking khelper thread. */ | |
234 | kmod_thread_locker = current; | |
235 | return ____call_usermodehelper(data); | |
236 | } | |
237 | ||
ae3cef73 | 238 | static void call_usermodehelper_freeinfo(struct subprocess_info *info) |
0ab4dc92 JF |
239 | { |
240 | if (info->cleanup) | |
a06a4dc3 | 241 | (*info->cleanup)(info); |
0ab4dc92 JF |
242 | kfree(info); |
243 | } | |
0ab4dc92 | 244 | |
b3449922 ON |
245 | static void umh_complete(struct subprocess_info *sub_info) |
246 | { | |
d0bd587a ON |
247 | struct completion *comp = xchg(&sub_info->complete, NULL); |
248 | /* | |
249 | * See call_usermodehelper_exec(). If xchg() returns NULL | |
250 | * we own sub_info, the UMH_KILLABLE caller has gone away. | |
251 | */ | |
252 | if (comp) | |
253 | complete(comp); | |
254 | else | |
255 | call_usermodehelper_freeinfo(sub_info); | |
b3449922 ON |
256 | } |
257 | ||
1da177e4 LT |
258 | /* Keventd can't block, but this (a child) can. */ |
259 | static int wait_for_helper(void *data) | |
260 | { | |
261 | struct subprocess_info *sub_info = data; | |
262 | pid_t pid; | |
1da177e4 | 263 | |
7d642242 ON |
264 | /* If SIGCLD is ignored sys_wait4 won't populate the status. */ |
265 | spin_lock_irq(¤t->sighand->siglock); | |
266 | current->sighand->action[SIGCHLD-1].sa.sa_handler = SIG_DFL; | |
267 | spin_unlock_irq(¤t->sighand->siglock); | |
1da177e4 LT |
268 | |
269 | pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD); | |
270 | if (pid < 0) { | |
271 | sub_info->retval = pid; | |
272 | } else { | |
7d642242 | 273 | int ret = -ECHILD; |
1da177e4 LT |
274 | /* |
275 | * Normally it is bogus to call wait4() from in-kernel because | |
276 | * wait4() wants to write the exit code to a userspace address. | |
277 | * But wait_for_helper() always runs as keventd, and put_user() | |
278 | * to a kernel address works OK for kernel threads, due to their | |
279 | * having an mm_segment_t which spans the entire address space. | |
280 | * | |
281 | * Thus the __user pointer cast is valid here. | |
282 | */ | |
111dbe0c BS |
283 | sys_wait4(pid, (int __user *)&ret, 0, NULL); |
284 | ||
285 | /* | |
286 | * If ret is 0, either ____call_usermodehelper failed and the | |
287 | * real error code is already in sub_info->retval or | |
288 | * sub_info->retval is 0 anyway, so don't mess with it then. | |
289 | */ | |
290 | if (ret) | |
291 | sub_info->retval = ret; | |
1da177e4 LT |
292 | } |
293 | ||
b3449922 | 294 | umh_complete(sub_info); |
1da177e4 LT |
295 | return 0; |
296 | } | |
297 | ||
298 | /* This is run by khelper thread */ | |
65f27f38 | 299 | static void __call_usermodehelper(struct work_struct *work) |
1da177e4 | 300 | { |
65f27f38 DH |
301 | struct subprocess_info *sub_info = |
302 | container_of(work, struct subprocess_info, work); | |
9d944ef3 | 303 | int wait = sub_info->wait & ~UMH_KILLABLE; |
d47419cd | 304 | pid_t pid; |
1da177e4 LT |
305 | |
306 | /* CLONE_VFORK: wait until the usermode helper has execve'd | |
307 | * successfully We need the data structures to stay around | |
308 | * until that is done. */ | |
d47419cd | 309 | if (wait == UMH_WAIT_PROC) |
1da177e4 LT |
310 | pid = kernel_thread(wait_for_helper, sub_info, |
311 | CLONE_FS | CLONE_FILES | SIGCHLD); | |
0f20784d TH |
312 | else { |
313 | pid = kernel_thread(call_helper, sub_info, | |
1da177e4 | 314 | CLONE_VFORK | SIGCHLD); |
0f20784d TH |
315 | /* Worker thread stopped blocking khelper thread. */ |
316 | kmod_thread_locker = NULL; | |
317 | } | |
1da177e4 | 318 | |
86313c48 JF |
319 | switch (wait) { |
320 | case UMH_NO_WAIT: | |
d47419cd | 321 | call_usermodehelper_freeinfo(sub_info); |
86313c48 | 322 | break; |
a98f0dd3 | 323 | |
86313c48 JF |
324 | case UMH_WAIT_PROC: |
325 | if (pid > 0) | |
326 | break; | |
86313c48 | 327 | /* FALLTHROUGH */ |
86313c48 | 328 | case UMH_WAIT_EXEC: |
04b1c384 ON |
329 | if (pid < 0) |
330 | sub_info->retval = pid; | |
b3449922 | 331 | umh_complete(sub_info); |
86313c48 | 332 | } |
1da177e4 LT |
333 | } |
334 | ||
ccd4b65a RW |
335 | /* |
336 | * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY | |
337 | * (used for preventing user land processes from being created after the user | |
338 | * land has been frozen during a system-wide hibernation or suspend operation). | |
b298d289 | 339 | * Should always be manipulated under umhelper_sem acquired for write. |
ccd4b65a | 340 | */ |
247bc037 | 341 | static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED; |
ccd4b65a RW |
342 | |
343 | /* Number of helpers running */ | |
344 | static atomic_t running_helpers = ATOMIC_INIT(0); | |
345 | ||
346 | /* | |
5307427a | 347 | * Wait queue head used by usermodehelper_disable() to wait for all running |
ccd4b65a RW |
348 | * helpers to finish. |
349 | */ | |
350 | static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); | |
351 | ||
9b78c1da RW |
352 | /* |
353 | * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled | |
354 | * to become 'false'. | |
355 | */ | |
356 | static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq); | |
357 | ||
ccd4b65a RW |
358 | /* |
359 | * Time to wait for running_helpers to become zero before the setting of | |
5307427a | 360 | * usermodehelper_disabled in usermodehelper_disable() fails |
ccd4b65a RW |
361 | */ |
362 | #define RUNNING_HELPERS_TIMEOUT (5 * HZ) | |
363 | ||
fe2e39d8 | 364 | int usermodehelper_read_trylock(void) |
b298d289 | 365 | { |
247bc037 | 366 | DEFINE_WAIT(wait); |
fe2e39d8 RW |
367 | int ret = 0; |
368 | ||
b298d289 | 369 | down_read(&umhelper_sem); |
247bc037 RW |
370 | for (;;) { |
371 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
372 | TASK_INTERRUPTIBLE); | |
373 | if (!usermodehelper_disabled) | |
374 | break; | |
375 | ||
376 | if (usermodehelper_disabled == UMH_DISABLED) | |
377 | ret = -EAGAIN; | |
378 | ||
fe2e39d8 | 379 | up_read(&umhelper_sem); |
247bc037 RW |
380 | |
381 | if (ret) | |
382 | break; | |
383 | ||
384 | schedule(); | |
385 | try_to_freeze(); | |
386 | ||
387 | down_read(&umhelper_sem); | |
fe2e39d8 | 388 | } |
247bc037 | 389 | finish_wait(&usermodehelper_disabled_waitq, &wait); |
fe2e39d8 | 390 | return ret; |
b298d289 | 391 | } |
fe2e39d8 | 392 | EXPORT_SYMBOL_GPL(usermodehelper_read_trylock); |
b298d289 | 393 | |
9b78c1da RW |
394 | long usermodehelper_read_lock_wait(long timeout) |
395 | { | |
396 | DEFINE_WAIT(wait); | |
397 | ||
398 | if (timeout < 0) | |
399 | return -EINVAL; | |
400 | ||
401 | down_read(&umhelper_sem); | |
402 | for (;;) { | |
403 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
404 | TASK_UNINTERRUPTIBLE); | |
405 | if (!usermodehelper_disabled) | |
406 | break; | |
407 | ||
408 | up_read(&umhelper_sem); | |
409 | ||
410 | timeout = schedule_timeout(timeout); | |
411 | if (!timeout) | |
412 | break; | |
413 | ||
414 | down_read(&umhelper_sem); | |
415 | } | |
416 | finish_wait(&usermodehelper_disabled_waitq, &wait); | |
417 | return timeout; | |
418 | } | |
419 | EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait); | |
420 | ||
fe2e39d8 | 421 | void usermodehelper_read_unlock(void) |
b298d289 SB |
422 | { |
423 | up_read(&umhelper_sem); | |
424 | } | |
fe2e39d8 | 425 | EXPORT_SYMBOL_GPL(usermodehelper_read_unlock); |
b298d289 | 426 | |
9b78c1da | 427 | /** |
247bc037 | 428 | * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled. |
9b3c98cd | 429 | * @depth: New value to assign to usermodehelper_disabled. |
247bc037 RW |
430 | * |
431 | * Change the value of usermodehelper_disabled (under umhelper_sem locked for | |
432 | * writing) and wakeup tasks waiting for it to change. | |
9b78c1da | 433 | */ |
247bc037 | 434 | void __usermodehelper_set_disable_depth(enum umh_disable_depth depth) |
9b78c1da RW |
435 | { |
436 | down_write(&umhelper_sem); | |
247bc037 | 437 | usermodehelper_disabled = depth; |
9b78c1da RW |
438 | wake_up(&usermodehelper_disabled_waitq); |
439 | up_write(&umhelper_sem); | |
440 | } | |
441 | ||
1bfcf130 | 442 | /** |
247bc037 RW |
443 | * __usermodehelper_disable - Prevent new helpers from being started. |
444 | * @depth: New value to assign to usermodehelper_disabled. | |
445 | * | |
446 | * Set usermodehelper_disabled to @depth and wait for running helpers to exit. | |
1bfcf130 | 447 | */ |
247bc037 | 448 | int __usermodehelper_disable(enum umh_disable_depth depth) |
8cdd4936 | 449 | { |
ccd4b65a RW |
450 | long retval; |
451 | ||
247bc037 RW |
452 | if (!depth) |
453 | return -EINVAL; | |
454 | ||
b298d289 | 455 | down_write(&umhelper_sem); |
247bc037 | 456 | usermodehelper_disabled = depth; |
b298d289 SB |
457 | up_write(&umhelper_sem); |
458 | ||
1bfcf130 RW |
459 | /* |
460 | * From now on call_usermodehelper_exec() won't start any new | |
461 | * helpers, so it is sufficient if running_helpers turns out to | |
462 | * be zero at one point (it may be increased later, but that | |
463 | * doesn't matter). | |
464 | */ | |
465 | retval = wait_event_timeout(running_helpers_waitq, | |
ccd4b65a RW |
466 | atomic_read(&running_helpers) == 0, |
467 | RUNNING_HELPERS_TIMEOUT); | |
1bfcf130 RW |
468 | if (retval) |
469 | return 0; | |
8cdd4936 | 470 | |
247bc037 | 471 | __usermodehelper_set_disable_depth(UMH_ENABLED); |
1bfcf130 RW |
472 | return -EAGAIN; |
473 | } | |
474 | ||
ccd4b65a RW |
475 | static void helper_lock(void) |
476 | { | |
477 | atomic_inc(&running_helpers); | |
478 | smp_mb__after_atomic_inc(); | |
479 | } | |
480 | ||
481 | static void helper_unlock(void) | |
482 | { | |
483 | if (atomic_dec_and_test(&running_helpers)) | |
484 | wake_up(&running_helpers_waitq); | |
485 | } | |
ccd4b65a | 486 | |
1da177e4 | 487 | /** |
0ab4dc92 | 488 | * call_usermodehelper_setup - prepare to call a usermode helper |
61df47c8 RD |
489 | * @path: path to usermode executable |
490 | * @argv: arg vector for process | |
491 | * @envp: environment for process | |
ac331d15 | 492 | * @gfp_mask: gfp mask for memory allocation |
0ab4dc92 | 493 | * |
61df47c8 | 494 | * Returns either %NULL on allocation failure, or a subprocess_info |
0ab4dc92 JF |
495 | * structure. This should be passed to call_usermodehelper_exec to |
496 | * exec the process and free the structure. | |
497 | */ | |
785042f2 | 498 | static |
ac331d15 KM |
499 | struct subprocess_info *call_usermodehelper_setup(char *path, char **argv, |
500 | char **envp, gfp_t gfp_mask) | |
0ab4dc92 JF |
501 | { |
502 | struct subprocess_info *sub_info; | |
ac331d15 | 503 | sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask); |
0ab4dc92 JF |
504 | if (!sub_info) |
505 | goto out; | |
506 | ||
507 | INIT_WORK(&sub_info->work, __call_usermodehelper); | |
508 | sub_info->path = path; | |
509 | sub_info->argv = argv; | |
510 | sub_info->envp = envp; | |
0ab4dc92 JF |
511 | out: |
512 | return sub_info; | |
513 | } | |
0ab4dc92 | 514 | |
0ab4dc92 | 515 | /** |
a06a4dc3 | 516 | * call_usermodehelper_setfns - set a cleanup/init function |
0ab4dc92 JF |
517 | * @info: a subprocess_info returned by call_usermodehelper_setup |
518 | * @cleanup: a cleanup function | |
a06a4dc3 NH |
519 | * @init: an init function |
520 | * @data: arbitrary context sensitive data | |
521 | * | |
522 | * The init function is used to customize the helper process prior to | |
523 | * exec. A non-zero return code causes the process to error out, exit, | |
524 | * and return the failure to the calling process | |
0ab4dc92 | 525 | * |
a06a4dc3 | 526 | * The cleanup function is just before ethe subprocess_info is about to |
0ab4dc92 JF |
527 | * be freed. This can be used for freeing the argv and envp. The |
528 | * Function must be runnable in either a process context or the | |
529 | * context in which call_usermodehelper_exec is called. | |
530 | */ | |
785042f2 | 531 | static |
a06a4dc3 | 532 | void call_usermodehelper_setfns(struct subprocess_info *info, |
87966996 | 533 | int (*init)(struct subprocess_info *info, struct cred *new), |
a06a4dc3 NH |
534 | void (*cleanup)(struct subprocess_info *info), |
535 | void *data) | |
0ab4dc92 JF |
536 | { |
537 | info->cleanup = cleanup; | |
a06a4dc3 NH |
538 | info->init = init; |
539 | info->data = data; | |
0ab4dc92 | 540 | } |
0ab4dc92 | 541 | |
0ab4dc92 JF |
542 | /** |
543 | * call_usermodehelper_exec - start a usermode application | |
544 | * @sub_info: information about the subprocessa | |
1da177e4 | 545 | * @wait: wait for the application to finish and return status. |
a98f0dd3 AK |
546 | * when -1 don't wait at all, but you get no useful error back when |
547 | * the program couldn't be exec'ed. This makes it safe to call | |
548 | * from interrupt context. | |
1da177e4 LT |
549 | * |
550 | * Runs a user-space application. The application is started | |
551 | * asynchronously if wait is not set, and runs as a child of keventd. | |
552 | * (ie. it runs with full root capabilities). | |
1da177e4 | 553 | */ |
785042f2 | 554 | static |
9d944ef3 | 555 | int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) |
1da177e4 | 556 | { |
60be6b9a | 557 | DECLARE_COMPLETION_ONSTACK(done); |
78468033 | 558 | int retval = 0; |
1da177e4 | 559 | |
ccd4b65a | 560 | helper_lock(); |
78468033 | 561 | if (sub_info->path[0] == '\0') |
0ab4dc92 | 562 | goto out; |
1da177e4 | 563 | |
8cdd4936 | 564 | if (!khelper_wq || usermodehelper_disabled) { |
0ab4dc92 JF |
565 | retval = -EBUSY; |
566 | goto out; | |
567 | } | |
0f20784d TH |
568 | /* |
569 | * Worker thread must not wait for khelper thread at below | |
570 | * wait_for_completion() if the thread was created with CLONE_VFORK | |
571 | * flag, for khelper thread is already waiting for the thread at | |
572 | * wait_for_completion() in do_fork(). | |
573 | */ | |
574 | if (wait != UMH_NO_WAIT && current == kmod_thread_locker) { | |
575 | retval = -EBUSY; | |
576 | goto out; | |
577 | } | |
a98f0dd3 | 578 | |
a98f0dd3 | 579 | sub_info->complete = &done; |
a98f0dd3 AK |
580 | sub_info->wait = wait; |
581 | ||
582 | queue_work(khelper_wq, &sub_info->work); | |
78468033 NC |
583 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ |
584 | goto unlock; | |
d0bd587a ON |
585 | |
586 | if (wait & UMH_KILLABLE) { | |
587 | retval = wait_for_completion_killable(&done); | |
588 | if (!retval) | |
589 | goto wait_done; | |
590 | ||
591 | /* umh_complete() will see NULL and free sub_info */ | |
592 | if (xchg(&sub_info->complete, NULL)) | |
593 | goto unlock; | |
594 | /* fallthrough, umh_complete() was already called */ | |
595 | } | |
596 | ||
1da177e4 | 597 | wait_for_completion(&done); |
d0bd587a | 598 | wait_done: |
a98f0dd3 | 599 | retval = sub_info->retval; |
78468033 | 600 | out: |
0ab4dc92 | 601 | call_usermodehelper_freeinfo(sub_info); |
78468033 | 602 | unlock: |
ccd4b65a | 603 | helper_unlock(); |
a98f0dd3 | 604 | return retval; |
1da177e4 | 605 | } |
785042f2 | 606 | |
79c743dd AM |
607 | /* |
608 | * call_usermodehelper_fns() will not run the caller-provided cleanup function | |
609 | * if a memory allocation failure is experienced. So the caller might need to | |
610 | * check the call_usermodehelper_fns() return value: if it is -ENOMEM, perform | |
611 | * the necessaary cleanup within the caller. | |
612 | */ | |
785042f2 BH |
613 | int call_usermodehelper_fns( |
614 | char *path, char **argv, char **envp, int wait, | |
615 | int (*init)(struct subprocess_info *info, struct cred *new), | |
616 | void (*cleanup)(struct subprocess_info *), void *data) | |
617 | { | |
618 | struct subprocess_info *info; | |
619 | gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL; | |
620 | ||
621 | info = call_usermodehelper_setup(path, argv, envp, gfp_mask); | |
622 | ||
623 | if (info == NULL) | |
624 | return -ENOMEM; | |
625 | ||
626 | call_usermodehelper_setfns(info, init, cleanup, data); | |
627 | ||
628 | return call_usermodehelper_exec(info, wait); | |
629 | } | |
630 | EXPORT_SYMBOL(call_usermodehelper_fns); | |
1da177e4 | 631 | |
17f60a7d EP |
632 | static int proc_cap_handler(struct ctl_table *table, int write, |
633 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
634 | { | |
635 | struct ctl_table t; | |
636 | unsigned long cap_array[_KERNEL_CAPABILITY_U32S]; | |
637 | kernel_cap_t new_cap; | |
638 | int err, i; | |
639 | ||
640 | if (write && (!capable(CAP_SETPCAP) || | |
641 | !capable(CAP_SYS_MODULE))) | |
642 | return -EPERM; | |
643 | ||
644 | /* | |
645 | * convert from the global kernel_cap_t to the ulong array to print to | |
646 | * userspace if this is a read. | |
647 | */ | |
648 | spin_lock(&umh_sysctl_lock); | |
649 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) { | |
650 | if (table->data == CAP_BSET) | |
651 | cap_array[i] = usermodehelper_bset.cap[i]; | |
652 | else if (table->data == CAP_PI) | |
653 | cap_array[i] = usermodehelper_inheritable.cap[i]; | |
654 | else | |
655 | BUG(); | |
656 | } | |
657 | spin_unlock(&umh_sysctl_lock); | |
658 | ||
659 | t = *table; | |
660 | t.data = &cap_array; | |
661 | ||
662 | /* | |
663 | * actually read or write and array of ulongs from userspace. Remember | |
664 | * these are least significant 32 bits first | |
665 | */ | |
666 | err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); | |
667 | if (err < 0) | |
668 | return err; | |
669 | ||
670 | /* | |
671 | * convert from the sysctl array of ulongs to the kernel_cap_t | |
672 | * internal representation | |
673 | */ | |
674 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) | |
675 | new_cap.cap[i] = cap_array[i]; | |
676 | ||
677 | /* | |
678 | * Drop everything not in the new_cap (but don't add things) | |
679 | */ | |
680 | spin_lock(&umh_sysctl_lock); | |
681 | if (write) { | |
682 | if (table->data == CAP_BSET) | |
683 | usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap); | |
684 | if (table->data == CAP_PI) | |
685 | usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap); | |
686 | } | |
687 | spin_unlock(&umh_sysctl_lock); | |
688 | ||
689 | return 0; | |
690 | } | |
691 | ||
692 | struct ctl_table usermodehelper_table[] = { | |
693 | { | |
694 | .procname = "bset", | |
695 | .data = CAP_BSET, | |
696 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
697 | .mode = 0600, | |
698 | .proc_handler = proc_cap_handler, | |
699 | }, | |
700 | { | |
701 | .procname = "inheritable", | |
702 | .data = CAP_PI, | |
703 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
704 | .mode = 0600, | |
705 | .proc_handler = proc_cap_handler, | |
706 | }, | |
707 | { } | |
708 | }; | |
709 | ||
1da177e4 LT |
710 | void __init usermodehelper_init(void) |
711 | { | |
712 | khelper_wq = create_singlethread_workqueue("khelper"); | |
713 | BUG_ON(!khelper_wq); | |
714 | } |