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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 LT |
27 | #include <linux/completion.h> |
28 | #include <linux/file.h> | |
9f3acc31 | 29 | #include <linux/fdtable.h> |
1da177e4 LT |
30 | #include <linux/workqueue.h> |
31 | #include <linux/security.h> | |
32 | #include <linux/mount.h> | |
33 | #include <linux/kernel.h> | |
34 | #include <linux/init.h> | |
d025c9db | 35 | #include <linux/resource.h> |
8cdd4936 RW |
36 | #include <linux/notifier.h> |
37 | #include <linux/suspend.h> | |
1da177e4 LT |
38 | #include <asm/uaccess.h> |
39 | ||
7ead8b83 LZ |
40 | #include <trace/events/module.h> |
41 | ||
1da177e4 LT |
42 | extern int max_threads; |
43 | ||
44 | static struct workqueue_struct *khelper_wq; | |
45 | ||
a1ef5adb | 46 | #ifdef CONFIG_MODULES |
1da177e4 LT |
47 | |
48 | /* | |
49 | modprobe_path is set via /proc/sys. | |
50 | */ | |
51 | char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe"; | |
52 | ||
53 | /** | |
acae0515 AV |
54 | * __request_module - try to load a kernel module |
55 | * @wait: wait (or not) for the operation to complete | |
bd4207c9 RD |
56 | * @fmt: printf style format string for the name of the module |
57 | * @...: arguments as specified in the format string | |
1da177e4 LT |
58 | * |
59 | * Load a module using the user mode module loader. The function returns | |
60 | * zero on success or a negative errno code on failure. Note that a | |
61 | * successful module load does not mean the module did not then unload | |
62 | * and exit on an error of its own. Callers must check that the service | |
63 | * they requested is now available not blindly invoke it. | |
64 | * | |
65 | * If module auto-loading support is disabled then this function | |
66 | * becomes a no-operation. | |
67 | */ | |
acae0515 | 68 | int __request_module(bool wait, const char *fmt, ...) |
1da177e4 LT |
69 | { |
70 | va_list args; | |
71 | char module_name[MODULE_NAME_LEN]; | |
72 | unsigned int max_modprobes; | |
73 | int ret; | |
74 | char *argv[] = { modprobe_path, "-q", "--", module_name, NULL }; | |
75 | static char *envp[] = { "HOME=/", | |
76 | "TERM=linux", | |
77 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
78 | NULL }; | |
79 | static atomic_t kmod_concurrent = ATOMIC_INIT(0); | |
80 | #define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */ | |
81 | static int kmod_loop_msg; | |
82 | ||
83 | va_start(args, fmt); | |
84 | ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args); | |
85 | va_end(args); | |
86 | if (ret >= MODULE_NAME_LEN) | |
87 | return -ENAMETOOLONG; | |
88 | ||
dd8dbf2e EP |
89 | ret = security_kernel_module_request(module_name); |
90 | if (ret) | |
91 | return ret; | |
92 | ||
1da177e4 LT |
93 | /* If modprobe needs a service that is in a module, we get a recursive |
94 | * loop. Limit the number of running kmod threads to max_threads/2 or | |
95 | * MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method | |
96 | * would be to run the parents of this process, counting how many times | |
97 | * kmod was invoked. That would mean accessing the internals of the | |
98 | * process tables to get the command line, proc_pid_cmdline is static | |
99 | * and it is not worth changing the proc code just to handle this case. | |
100 | * KAO. | |
101 | * | |
102 | * "trace the ppid" is simple, but will fail if someone's | |
103 | * parent exits. I think this is as good as it gets. --RR | |
104 | */ | |
105 | max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT); | |
106 | atomic_inc(&kmod_concurrent); | |
107 | if (atomic_read(&kmod_concurrent) > max_modprobes) { | |
108 | /* We may be blaming an innocent here, but unlikely */ | |
109 | if (kmod_loop_msg++ < 5) | |
110 | printk(KERN_ERR | |
111 | "request_module: runaway loop modprobe %s\n", | |
112 | module_name); | |
113 | atomic_dec(&kmod_concurrent); | |
114 | return -ENOMEM; | |
115 | } | |
116 | ||
7ead8b83 LZ |
117 | trace_module_request(module_name, wait, _RET_IP_); |
118 | ||
a06a4dc3 NH |
119 | ret = call_usermodehelper_fns(modprobe_path, argv, envp, |
120 | wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC, | |
121 | NULL, NULL, NULL); | |
122 | ||
1da177e4 LT |
123 | atomic_dec(&kmod_concurrent); |
124 | return ret; | |
125 | } | |
acae0515 | 126 | EXPORT_SYMBOL(__request_module); |
118a9069 | 127 | #endif /* CONFIG_MODULES */ |
1da177e4 | 128 | |
1da177e4 LT |
129 | /* |
130 | * This is the task which runs the usermode application | |
131 | */ | |
132 | static int ____call_usermodehelper(void *data) | |
133 | { | |
134 | struct subprocess_info *sub_info = data; | |
135 | int retval; | |
136 | ||
d84f4f99 DH |
137 | BUG_ON(atomic_read(&sub_info->cred->usage) != 1); |
138 | ||
139 | /* Unblock all signals */ | |
1da177e4 LT |
140 | spin_lock_irq(¤t->sighand->siglock); |
141 | flush_signal_handlers(current, 1); | |
142 | sigemptyset(¤t->blocked); | |
143 | recalc_sigpending(); | |
144 | spin_unlock_irq(¤t->sighand->siglock); | |
145 | ||
d84f4f99 DH |
146 | /* Install the credentials */ |
147 | commit_creds(sub_info->cred); | |
148 | sub_info->cred = NULL; | |
7888e7ff | 149 | |
1da177e4 | 150 | /* We can run anywhere, unlike our parent keventd(). */ |
1a2142af | 151 | set_cpus_allowed_ptr(current, cpu_all_mask); |
1da177e4 | 152 | |
b73a7e76 JE |
153 | /* |
154 | * Our parent is keventd, which runs with elevated scheduling priority. | |
155 | * Avoid propagating that into the userspace child. | |
156 | */ | |
157 | set_user_nice(current, 0); | |
158 | ||
a06a4dc3 NH |
159 | if (sub_info->init) { |
160 | retval = sub_info->init(sub_info); | |
161 | if (retval) | |
162 | goto fail; | |
163 | } | |
164 | ||
db74ece9 | 165 | retval = kernel_execve(sub_info->path, sub_info->argv, sub_info->envp); |
1da177e4 LT |
166 | |
167 | /* Exec failed? */ | |
a06a4dc3 | 168 | fail: |
1da177e4 LT |
169 | sub_info->retval = retval; |
170 | do_exit(0); | |
171 | } | |
172 | ||
0ab4dc92 JF |
173 | void call_usermodehelper_freeinfo(struct subprocess_info *info) |
174 | { | |
175 | if (info->cleanup) | |
a06a4dc3 | 176 | (*info->cleanup)(info); |
d84f4f99 DH |
177 | if (info->cred) |
178 | put_cred(info->cred); | |
0ab4dc92 JF |
179 | kfree(info); |
180 | } | |
181 | EXPORT_SYMBOL(call_usermodehelper_freeinfo); | |
182 | ||
1da177e4 LT |
183 | /* Keventd can't block, but this (a child) can. */ |
184 | static int wait_for_helper(void *data) | |
185 | { | |
186 | struct subprocess_info *sub_info = data; | |
187 | pid_t pid; | |
1da177e4 LT |
188 | |
189 | /* Install a handler: if SIGCLD isn't handled sys_wait4 won't | |
190 | * populate the status, but will return -ECHILD. */ | |
1da177e4 LT |
191 | allow_signal(SIGCHLD); |
192 | ||
193 | pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD); | |
194 | if (pid < 0) { | |
195 | sub_info->retval = pid; | |
196 | } else { | |
111dbe0c BS |
197 | int ret; |
198 | ||
1da177e4 LT |
199 | /* |
200 | * Normally it is bogus to call wait4() from in-kernel because | |
201 | * wait4() wants to write the exit code to a userspace address. | |
202 | * But wait_for_helper() always runs as keventd, and put_user() | |
203 | * to a kernel address works OK for kernel threads, due to their | |
204 | * having an mm_segment_t which spans the entire address space. | |
205 | * | |
206 | * Thus the __user pointer cast is valid here. | |
207 | */ | |
111dbe0c BS |
208 | sys_wait4(pid, (int __user *)&ret, 0, NULL); |
209 | ||
210 | /* | |
211 | * If ret is 0, either ____call_usermodehelper failed and the | |
212 | * real error code is already in sub_info->retval or | |
213 | * sub_info->retval is 0 anyway, so don't mess with it then. | |
214 | */ | |
215 | if (ret) | |
216 | sub_info->retval = ret; | |
1da177e4 LT |
217 | } |
218 | ||
86313c48 | 219 | if (sub_info->wait == UMH_NO_WAIT) |
0ab4dc92 | 220 | call_usermodehelper_freeinfo(sub_info); |
a98f0dd3 AK |
221 | else |
222 | complete(sub_info->complete); | |
1da177e4 LT |
223 | return 0; |
224 | } | |
225 | ||
226 | /* This is run by khelper thread */ | |
65f27f38 | 227 | static void __call_usermodehelper(struct work_struct *work) |
1da177e4 | 228 | { |
65f27f38 DH |
229 | struct subprocess_info *sub_info = |
230 | container_of(work, struct subprocess_info, work); | |
1da177e4 | 231 | pid_t pid; |
86313c48 | 232 | enum umh_wait wait = sub_info->wait; |
1da177e4 | 233 | |
d84f4f99 DH |
234 | BUG_ON(atomic_read(&sub_info->cred->usage) != 1); |
235 | ||
1da177e4 LT |
236 | /* CLONE_VFORK: wait until the usermode helper has execve'd |
237 | * successfully We need the data structures to stay around | |
238 | * until that is done. */ | |
86313c48 | 239 | if (wait == UMH_WAIT_PROC || wait == UMH_NO_WAIT) |
1da177e4 LT |
240 | pid = kernel_thread(wait_for_helper, sub_info, |
241 | CLONE_FS | CLONE_FILES | SIGCHLD); | |
242 | else | |
243 | pid = kernel_thread(____call_usermodehelper, sub_info, | |
244 | CLONE_VFORK | SIGCHLD); | |
245 | ||
86313c48 JF |
246 | switch (wait) { |
247 | case UMH_NO_WAIT: | |
248 | break; | |
a98f0dd3 | 249 | |
86313c48 JF |
250 | case UMH_WAIT_PROC: |
251 | if (pid > 0) | |
252 | break; | |
1da177e4 | 253 | sub_info->retval = pid; |
86313c48 JF |
254 | /* FALLTHROUGH */ |
255 | ||
256 | case UMH_WAIT_EXEC: | |
1da177e4 | 257 | complete(sub_info->complete); |
86313c48 | 258 | } |
1da177e4 LT |
259 | } |
260 | ||
1bfcf130 | 261 | #ifdef CONFIG_PM_SLEEP |
ccd4b65a RW |
262 | /* |
263 | * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY | |
264 | * (used for preventing user land processes from being created after the user | |
265 | * land has been frozen during a system-wide hibernation or suspend operation). | |
266 | */ | |
267 | static int usermodehelper_disabled; | |
268 | ||
269 | /* Number of helpers running */ | |
270 | static atomic_t running_helpers = ATOMIC_INIT(0); | |
271 | ||
272 | /* | |
273 | * Wait queue head used by usermodehelper_pm_callback() to wait for all running | |
274 | * helpers to finish. | |
275 | */ | |
276 | static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); | |
277 | ||
278 | /* | |
279 | * Time to wait for running_helpers to become zero before the setting of | |
280 | * usermodehelper_disabled in usermodehelper_pm_callback() fails | |
281 | */ | |
282 | #define RUNNING_HELPERS_TIMEOUT (5 * HZ) | |
283 | ||
1bfcf130 RW |
284 | /** |
285 | * usermodehelper_disable - prevent new helpers from being started | |
286 | */ | |
287 | int usermodehelper_disable(void) | |
8cdd4936 | 288 | { |
ccd4b65a RW |
289 | long retval; |
290 | ||
1bfcf130 RW |
291 | usermodehelper_disabled = 1; |
292 | smp_mb(); | |
293 | /* | |
294 | * From now on call_usermodehelper_exec() won't start any new | |
295 | * helpers, so it is sufficient if running_helpers turns out to | |
296 | * be zero at one point (it may be increased later, but that | |
297 | * doesn't matter). | |
298 | */ | |
299 | retval = wait_event_timeout(running_helpers_waitq, | |
ccd4b65a RW |
300 | atomic_read(&running_helpers) == 0, |
301 | RUNNING_HELPERS_TIMEOUT); | |
1bfcf130 RW |
302 | if (retval) |
303 | return 0; | |
8cdd4936 | 304 | |
1bfcf130 RW |
305 | usermodehelper_disabled = 0; |
306 | return -EAGAIN; | |
307 | } | |
308 | ||
309 | /** | |
310 | * usermodehelper_enable - allow new helpers to be started again | |
311 | */ | |
312 | void usermodehelper_enable(void) | |
313 | { | |
314 | usermodehelper_disabled = 0; | |
8cdd4936 RW |
315 | } |
316 | ||
ccd4b65a RW |
317 | static void helper_lock(void) |
318 | { | |
319 | atomic_inc(&running_helpers); | |
320 | smp_mb__after_atomic_inc(); | |
321 | } | |
322 | ||
323 | static void helper_unlock(void) | |
324 | { | |
325 | if (atomic_dec_and_test(&running_helpers)) | |
326 | wake_up(&running_helpers_waitq); | |
327 | } | |
1bfcf130 | 328 | #else /* CONFIG_PM_SLEEP */ |
ccd4b65a RW |
329 | #define usermodehelper_disabled 0 |
330 | ||
331 | static inline void helper_lock(void) {} | |
332 | static inline void helper_unlock(void) {} | |
1bfcf130 | 333 | #endif /* CONFIG_PM_SLEEP */ |
ccd4b65a | 334 | |
1da177e4 | 335 | /** |
0ab4dc92 | 336 | * call_usermodehelper_setup - prepare to call a usermode helper |
61df47c8 RD |
337 | * @path: path to usermode executable |
338 | * @argv: arg vector for process | |
339 | * @envp: environment for process | |
ac331d15 | 340 | * @gfp_mask: gfp mask for memory allocation |
0ab4dc92 | 341 | * |
61df47c8 | 342 | * Returns either %NULL on allocation failure, or a subprocess_info |
0ab4dc92 JF |
343 | * structure. This should be passed to call_usermodehelper_exec to |
344 | * exec the process and free the structure. | |
345 | */ | |
ac331d15 KM |
346 | struct subprocess_info *call_usermodehelper_setup(char *path, char **argv, |
347 | char **envp, gfp_t gfp_mask) | |
0ab4dc92 JF |
348 | { |
349 | struct subprocess_info *sub_info; | |
ac331d15 | 350 | sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask); |
0ab4dc92 JF |
351 | if (!sub_info) |
352 | goto out; | |
353 | ||
354 | INIT_WORK(&sub_info->work, __call_usermodehelper); | |
355 | sub_info->path = path; | |
356 | sub_info->argv = argv; | |
357 | sub_info->envp = envp; | |
d84f4f99 | 358 | sub_info->cred = prepare_usermodehelper_creds(); |
ab2b7eba TH |
359 | if (!sub_info->cred) { |
360 | kfree(sub_info); | |
d84f4f99 | 361 | return NULL; |
ab2b7eba | 362 | } |
0ab4dc92 JF |
363 | |
364 | out: | |
365 | return sub_info; | |
366 | } | |
367 | EXPORT_SYMBOL(call_usermodehelper_setup); | |
368 | ||
369 | /** | |
370 | * call_usermodehelper_setkeys - set the session keys for usermode helper | |
371 | * @info: a subprocess_info returned by call_usermodehelper_setup | |
372 | * @session_keyring: the session keyring for the process | |
373 | */ | |
374 | void call_usermodehelper_setkeys(struct subprocess_info *info, | |
375 | struct key *session_keyring) | |
376 | { | |
d84f4f99 DH |
377 | #ifdef CONFIG_KEYS |
378 | struct thread_group_cred *tgcred = info->cred->tgcred; | |
379 | key_put(tgcred->session_keyring); | |
380 | tgcred->session_keyring = key_get(session_keyring); | |
381 | #else | |
382 | BUG(); | |
383 | #endif | |
0ab4dc92 JF |
384 | } |
385 | EXPORT_SYMBOL(call_usermodehelper_setkeys); | |
386 | ||
387 | /** | |
a06a4dc3 | 388 | * call_usermodehelper_setfns - set a cleanup/init function |
0ab4dc92 JF |
389 | * @info: a subprocess_info returned by call_usermodehelper_setup |
390 | * @cleanup: a cleanup function | |
a06a4dc3 NH |
391 | * @init: an init function |
392 | * @data: arbitrary context sensitive data | |
393 | * | |
394 | * The init function is used to customize the helper process prior to | |
395 | * exec. A non-zero return code causes the process to error out, exit, | |
396 | * and return the failure to the calling process | |
0ab4dc92 | 397 | * |
a06a4dc3 | 398 | * The cleanup function is just before ethe subprocess_info is about to |
0ab4dc92 JF |
399 | * be freed. This can be used for freeing the argv and envp. The |
400 | * Function must be runnable in either a process context or the | |
401 | * context in which call_usermodehelper_exec is called. | |
402 | */ | |
a06a4dc3 NH |
403 | void call_usermodehelper_setfns(struct subprocess_info *info, |
404 | int (*init)(struct subprocess_info *info), | |
405 | void (*cleanup)(struct subprocess_info *info), | |
406 | void *data) | |
0ab4dc92 JF |
407 | { |
408 | info->cleanup = cleanup; | |
a06a4dc3 NH |
409 | info->init = init; |
410 | info->data = data; | |
0ab4dc92 | 411 | } |
a06a4dc3 | 412 | EXPORT_SYMBOL(call_usermodehelper_setfns); |
0ab4dc92 | 413 | |
0ab4dc92 JF |
414 | /** |
415 | * call_usermodehelper_exec - start a usermode application | |
416 | * @sub_info: information about the subprocessa | |
1da177e4 | 417 | * @wait: wait for the application to finish and return status. |
a98f0dd3 AK |
418 | * when -1 don't wait at all, but you get no useful error back when |
419 | * the program couldn't be exec'ed. This makes it safe to call | |
420 | * from interrupt context. | |
1da177e4 LT |
421 | * |
422 | * Runs a user-space application. The application is started | |
423 | * asynchronously if wait is not set, and runs as a child of keventd. | |
424 | * (ie. it runs with full root capabilities). | |
1da177e4 | 425 | */ |
0ab4dc92 | 426 | int call_usermodehelper_exec(struct subprocess_info *sub_info, |
86313c48 | 427 | enum umh_wait wait) |
1da177e4 | 428 | { |
60be6b9a | 429 | DECLARE_COMPLETION_ONSTACK(done); |
78468033 | 430 | int retval = 0; |
1da177e4 | 431 | |
d84f4f99 | 432 | BUG_ON(atomic_read(&sub_info->cred->usage) != 1); |
e0e81739 | 433 | validate_creds(sub_info->cred); |
d84f4f99 | 434 | |
ccd4b65a | 435 | helper_lock(); |
78468033 | 436 | if (sub_info->path[0] == '\0') |
0ab4dc92 | 437 | goto out; |
1da177e4 | 438 | |
8cdd4936 | 439 | if (!khelper_wq || usermodehelper_disabled) { |
0ab4dc92 JF |
440 | retval = -EBUSY; |
441 | goto out; | |
442 | } | |
a98f0dd3 | 443 | |
a98f0dd3 | 444 | sub_info->complete = &done; |
a98f0dd3 AK |
445 | sub_info->wait = wait; |
446 | ||
447 | queue_work(khelper_wq, &sub_info->work); | |
78468033 NC |
448 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ |
449 | goto unlock; | |
1da177e4 | 450 | wait_for_completion(&done); |
a98f0dd3 | 451 | retval = sub_info->retval; |
0ab4dc92 | 452 | |
78468033 | 453 | out: |
0ab4dc92 | 454 | call_usermodehelper_freeinfo(sub_info); |
78468033 | 455 | unlock: |
ccd4b65a | 456 | helper_unlock(); |
a98f0dd3 | 457 | return retval; |
1da177e4 | 458 | } |
0ab4dc92 | 459 | EXPORT_SYMBOL(call_usermodehelper_exec); |
1da177e4 LT |
460 | |
461 | void __init usermodehelper_init(void) | |
462 | { | |
463 | khelper_wq = create_singlethread_workqueue("khelper"); | |
464 | BUG_ON(!khelper_wq); | |
465 | } |