Commit | Line | Data |
---|---|---|
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 | ||
17f60a7d EP |
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); | |
b298d289 | 54 | static DECLARE_RWSEM(umhelper_sem); |
17f60a7d | 55 | |
a1ef5adb | 56 | #ifdef CONFIG_MODULES |
1da177e4 LT |
57 | |
58 | /* | |
59 | modprobe_path is set via /proc/sys. | |
60 | */ | |
61 | char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe"; | |
62 | ||
1cc684ab ON |
63 | static void free_modprobe_argv(struct subprocess_info *info) |
64 | { | |
65 | kfree(info->argv[3]); /* check call_modprobe() */ | |
66 | kfree(info->argv); | |
67 | } | |
68 | ||
3e63a93b ON |
69 | static int call_modprobe(char *module_name, int wait) |
70 | { | |
f634460c | 71 | struct subprocess_info *info; |
3e63a93b ON |
72 | static char *envp[] = { |
73 | "HOME=/", | |
74 | "TERM=linux", | |
75 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
76 | NULL | |
77 | }; | |
78 | ||
1cc684ab ON |
79 | char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL); |
80 | if (!argv) | |
81 | goto out; | |
82 | ||
83 | module_name = kstrdup(module_name, GFP_KERNEL); | |
84 | if (!module_name) | |
85 | goto free_argv; | |
86 | ||
87 | argv[0] = modprobe_path; | |
88 | argv[1] = "-q"; | |
89 | argv[2] = "--"; | |
90 | argv[3] = module_name; /* check free_modprobe_argv() */ | |
91 | argv[4] = NULL; | |
3e63a93b | 92 | |
f634460c LDM |
93 | info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL, |
94 | NULL, free_modprobe_argv, NULL); | |
95 | if (!info) | |
96 | goto free_module_name; | |
97 | ||
98 | return call_usermodehelper_exec(info, wait | UMH_KILLABLE); | |
99 | ||
100 | free_module_name: | |
101 | kfree(module_name); | |
1cc684ab ON |
102 | free_argv: |
103 | kfree(argv); | |
104 | out: | |
105 | return -ENOMEM; | |
3e63a93b ON |
106 | } |
107 | ||
1da177e4 | 108 | /** |
acae0515 AV |
109 | * __request_module - try to load a kernel module |
110 | * @wait: wait (or not) for the operation to complete | |
bd4207c9 RD |
111 | * @fmt: printf style format string for the name of the module |
112 | * @...: arguments as specified in the format string | |
1da177e4 LT |
113 | * |
114 | * Load a module using the user mode module loader. The function returns | |
60b61a6f N |
115 | * zero on success or a negative errno code or positive exit code from |
116 | * "modprobe" on failure. Note that a successful module load does not mean | |
117 | * the module did not then unload and exit on an error of its own. Callers | |
118 | * must check that the service they requested is now available not blindly | |
119 | * invoke it. | |
1da177e4 LT |
120 | * |
121 | * If module auto-loading support is disabled then this function | |
122 | * becomes a no-operation. | |
123 | */ | |
acae0515 | 124 | int __request_module(bool wait, const char *fmt, ...) |
1da177e4 LT |
125 | { |
126 | va_list args; | |
127 | char module_name[MODULE_NAME_LEN]; | |
128 | unsigned int max_modprobes; | |
129 | int ret; | |
1da177e4 LT |
130 | static atomic_t kmod_concurrent = ATOMIC_INIT(0); |
131 | #define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */ | |
132 | static int kmod_loop_msg; | |
133 | ||
0fdff3ec TH |
134 | /* |
135 | * We don't allow synchronous module loading from async. Module | |
136 | * init may invoke async_synchronize_full() which will end up | |
137 | * waiting for this task which already is waiting for the module | |
138 | * loading to complete, leading to a deadlock. | |
139 | */ | |
140 | WARN_ON_ONCE(wait && current_is_async()); | |
141 | ||
7f57cfa4 ON |
142 | if (!modprobe_path[0]) |
143 | return 0; | |
144 | ||
1da177e4 LT |
145 | va_start(args, fmt); |
146 | ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args); | |
147 | va_end(args); | |
148 | if (ret >= MODULE_NAME_LEN) | |
149 | return -ENAMETOOLONG; | |
150 | ||
dd8dbf2e EP |
151 | ret = security_kernel_module_request(module_name); |
152 | if (ret) | |
153 | return ret; | |
154 | ||
1da177e4 LT |
155 | /* If modprobe needs a service that is in a module, we get a recursive |
156 | * loop. Limit the number of running kmod threads to max_threads/2 or | |
157 | * MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method | |
158 | * would be to run the parents of this process, counting how many times | |
159 | * kmod was invoked. That would mean accessing the internals of the | |
160 | * process tables to get the command line, proc_pid_cmdline is static | |
161 | * and it is not worth changing the proc code just to handle this case. | |
162 | * KAO. | |
163 | * | |
164 | * "trace the ppid" is simple, but will fail if someone's | |
165 | * parent exits. I think this is as good as it gets. --RR | |
166 | */ | |
167 | max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT); | |
168 | atomic_inc(&kmod_concurrent); | |
169 | if (atomic_read(&kmod_concurrent) > max_modprobes) { | |
170 | /* We may be blaming an innocent here, but unlikely */ | |
37252db6 | 171 | if (kmod_loop_msg < 5) { |
1da177e4 LT |
172 | printk(KERN_ERR |
173 | "request_module: runaway loop modprobe %s\n", | |
174 | module_name); | |
37252db6 JK |
175 | kmod_loop_msg++; |
176 | } | |
1da177e4 LT |
177 | atomic_dec(&kmod_concurrent); |
178 | return -ENOMEM; | |
179 | } | |
180 | ||
7ead8b83 LZ |
181 | trace_module_request(module_name, wait, _RET_IP_); |
182 | ||
3e63a93b | 183 | ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC); |
a06a4dc3 | 184 | |
1da177e4 LT |
185 | atomic_dec(&kmod_concurrent); |
186 | return ret; | |
187 | } | |
acae0515 | 188 | EXPORT_SYMBOL(__request_module); |
118a9069 | 189 | #endif /* CONFIG_MODULES */ |
1da177e4 | 190 | |
0baf2a4d MS |
191 | static void call_usermodehelper_freeinfo(struct subprocess_info *info) |
192 | { | |
193 | if (info->cleanup) | |
194 | (*info->cleanup)(info); | |
195 | kfree(info); | |
196 | } | |
197 | ||
198 | static void umh_complete(struct subprocess_info *sub_info) | |
199 | { | |
200 | struct completion *comp = xchg(&sub_info->complete, NULL); | |
201 | /* | |
202 | * See call_usermodehelper_exec(). If xchg() returns NULL | |
203 | * we own sub_info, the UMH_KILLABLE caller has gone away | |
204 | * or the caller used UMH_NO_WAIT. | |
205 | */ | |
206 | if (comp) | |
207 | complete(comp); | |
208 | else | |
209 | call_usermodehelper_freeinfo(sub_info); | |
210 | } | |
211 | ||
1da177e4 LT |
212 | /* |
213 | * This is the task which runs the usermode application | |
214 | */ | |
b6b50a81 | 215 | static int call_usermodehelper_exec_async(void *data) |
1da177e4 LT |
216 | { |
217 | struct subprocess_info *sub_info = data; | |
17f60a7d | 218 | struct cred *new; |
1da177e4 LT |
219 | int retval; |
220 | ||
1da177e4 LT |
221 | spin_lock_irq(¤t->sighand->siglock); |
222 | flush_signal_handlers(current, 1); | |
1da177e4 LT |
223 | spin_unlock_irq(¤t->sighand->siglock); |
224 | ||
b73a7e76 | 225 | /* |
90f02303 | 226 | * Our parent (unbound workqueue) runs with elevated scheduling |
b639e86b | 227 | * priority. Avoid propagating that into the userspace child. |
b73a7e76 JE |
228 | */ |
229 | set_user_nice(current, 0); | |
230 | ||
17f60a7d EP |
231 | retval = -ENOMEM; |
232 | new = prepare_kernel_cred(current); | |
233 | if (!new) | |
0baf2a4d | 234 | goto out; |
17f60a7d EP |
235 | |
236 | spin_lock(&umh_sysctl_lock); | |
237 | new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset); | |
238 | new->cap_inheritable = cap_intersect(usermodehelper_inheritable, | |
239 | new->cap_inheritable); | |
240 | spin_unlock(&umh_sysctl_lock); | |
241 | ||
87966996 DH |
242 | if (sub_info->init) { |
243 | retval = sub_info->init(sub_info, new); | |
244 | if (retval) { | |
245 | abort_creds(new); | |
0baf2a4d | 246 | goto out; |
87966996 DH |
247 | } |
248 | } | |
249 | ||
17f60a7d EP |
250 | commit_creds(new); |
251 | ||
c4ad8f98 | 252 | retval = do_execve(getname_kernel(sub_info->path), |
ae903caa AV |
253 | (const char __user *const __user *)sub_info->argv, |
254 | (const char __user *const __user *)sub_info->envp); | |
0baf2a4d MS |
255 | out: |
256 | sub_info->retval = retval; | |
b6b50a81 FW |
257 | /* |
258 | * call_usermodehelper_exec_sync() will call umh_complete | |
259 | * if UHM_WAIT_PROC. | |
260 | */ | |
7117bc88 | 261 | if (!(sub_info->wait & UMH_WAIT_PROC)) |
0baf2a4d | 262 | umh_complete(sub_info); |
a74fb73c AV |
263 | if (!retval) |
264 | return 0; | |
fb45550d | 265 | do_exit(0); |
1da177e4 LT |
266 | } |
267 | ||
bb304a5c FW |
268 | /* Handles UMH_WAIT_PROC. */ |
269 | static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info) | |
1da177e4 | 270 | { |
1da177e4 | 271 | pid_t pid; |
1da177e4 | 272 | |
7d642242 | 273 | /* If SIGCLD is ignored sys_wait4 won't populate the status. */ |
76e0a6f4 | 274 | kernel_sigaction(SIGCHLD, SIG_DFL); |
b6b50a81 | 275 | pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD); |
1da177e4 LT |
276 | if (pid < 0) { |
277 | sub_info->retval = pid; | |
278 | } else { | |
7d642242 | 279 | int ret = -ECHILD; |
1da177e4 LT |
280 | /* |
281 | * Normally it is bogus to call wait4() from in-kernel because | |
282 | * wait4() wants to write the exit code to a userspace address. | |
b639e86b | 283 | * But call_usermodehelper_exec_sync() always runs as kernel |
bb304a5c FW |
284 | * thread (workqueue) and put_user() to a kernel address works |
285 | * OK for kernel threads, due to their having an mm_segment_t | |
286 | * which spans the entire address space. | |
1da177e4 LT |
287 | * |
288 | * Thus the __user pointer cast is valid here. | |
289 | */ | |
111dbe0c BS |
290 | sys_wait4(pid, (int __user *)&ret, 0, NULL); |
291 | ||
292 | /* | |
b6b50a81 FW |
293 | * If ret is 0, either call_usermodehelper_exec_async failed and |
294 | * the real error code is already in sub_info->retval or | |
111dbe0c BS |
295 | * sub_info->retval is 0 anyway, so don't mess with it then. |
296 | */ | |
297 | if (ret) | |
298 | sub_info->retval = ret; | |
1da177e4 LT |
299 | } |
300 | ||
bb304a5c FW |
301 | /* Restore default kernel sig handler */ |
302 | kernel_sigaction(SIGCHLD, SIG_IGN); | |
303 | ||
b3449922 | 304 | umh_complete(sub_info); |
1da177e4 LT |
305 | } |
306 | ||
b639e86b | 307 | /* |
bb304a5c | 308 | * We need to create the usermodehelper kernel thread from a task that is affine |
90f02303 FW |
309 | * to an optimized set of CPUs (or nohz housekeeping ones) such that they |
310 | * inherit a widest affinity irrespective of call_usermodehelper() callers with | |
311 | * possibly reduced affinity (eg: per-cpu workqueues). We don't want | |
312 | * usermodehelper targets to contend a busy CPU. | |
313 | * | |
bb304a5c FW |
314 | * Unbound workqueues provide such wide affinity and allow to block on |
315 | * UMH_WAIT_PROC requests without blocking pending request (up to some limit). | |
b639e86b | 316 | * |
90f02303 FW |
317 | * Besides, workqueues provide the privilege level that caller might not have |
318 | * to perform the usermodehelper request. | |
b639e86b FW |
319 | * |
320 | */ | |
b6b50a81 | 321 | static void call_usermodehelper_exec_work(struct work_struct *work) |
1da177e4 | 322 | { |
65f27f38 DH |
323 | struct subprocess_info *sub_info = |
324 | container_of(work, struct subprocess_info, work); | |
1da177e4 | 325 | |
bb304a5c FW |
326 | if (sub_info->wait & UMH_WAIT_PROC) { |
327 | call_usermodehelper_exec_sync(sub_info); | |
328 | } else { | |
329 | pid_t pid; | |
330 | ||
b6b50a81 | 331 | pid = kernel_thread(call_usermodehelper_exec_async, sub_info, |
7f6def9f | 332 | SIGCHLD); |
bb304a5c FW |
333 | if (pid < 0) { |
334 | sub_info->retval = pid; | |
335 | umh_complete(sub_info); | |
336 | } | |
86313c48 | 337 | } |
1da177e4 LT |
338 | } |
339 | ||
ccd4b65a RW |
340 | /* |
341 | * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY | |
342 | * (used for preventing user land processes from being created after the user | |
343 | * land has been frozen during a system-wide hibernation or suspend operation). | |
b298d289 | 344 | * Should always be manipulated under umhelper_sem acquired for write. |
ccd4b65a | 345 | */ |
247bc037 | 346 | static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED; |
ccd4b65a RW |
347 | |
348 | /* Number of helpers running */ | |
349 | static atomic_t running_helpers = ATOMIC_INIT(0); | |
350 | ||
351 | /* | |
5307427a | 352 | * Wait queue head used by usermodehelper_disable() to wait for all running |
ccd4b65a RW |
353 | * helpers to finish. |
354 | */ | |
355 | static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); | |
356 | ||
9b78c1da RW |
357 | /* |
358 | * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled | |
359 | * to become 'false'. | |
360 | */ | |
361 | static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq); | |
362 | ||
ccd4b65a RW |
363 | /* |
364 | * Time to wait for running_helpers to become zero before the setting of | |
5307427a | 365 | * usermodehelper_disabled in usermodehelper_disable() fails |
ccd4b65a RW |
366 | */ |
367 | #define RUNNING_HELPERS_TIMEOUT (5 * HZ) | |
368 | ||
fe2e39d8 | 369 | int usermodehelper_read_trylock(void) |
b298d289 | 370 | { |
247bc037 | 371 | DEFINE_WAIT(wait); |
fe2e39d8 RW |
372 | int ret = 0; |
373 | ||
b298d289 | 374 | down_read(&umhelper_sem); |
247bc037 RW |
375 | for (;;) { |
376 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
377 | TASK_INTERRUPTIBLE); | |
378 | if (!usermodehelper_disabled) | |
379 | break; | |
380 | ||
381 | if (usermodehelper_disabled == UMH_DISABLED) | |
382 | ret = -EAGAIN; | |
383 | ||
fe2e39d8 | 384 | up_read(&umhelper_sem); |
247bc037 RW |
385 | |
386 | if (ret) | |
387 | break; | |
388 | ||
389 | schedule(); | |
390 | try_to_freeze(); | |
391 | ||
392 | down_read(&umhelper_sem); | |
fe2e39d8 | 393 | } |
247bc037 | 394 | finish_wait(&usermodehelper_disabled_waitq, &wait); |
fe2e39d8 | 395 | return ret; |
b298d289 | 396 | } |
fe2e39d8 | 397 | EXPORT_SYMBOL_GPL(usermodehelper_read_trylock); |
b298d289 | 398 | |
9b78c1da RW |
399 | long usermodehelper_read_lock_wait(long timeout) |
400 | { | |
401 | DEFINE_WAIT(wait); | |
402 | ||
403 | if (timeout < 0) | |
404 | return -EINVAL; | |
405 | ||
406 | down_read(&umhelper_sem); | |
407 | for (;;) { | |
408 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
409 | TASK_UNINTERRUPTIBLE); | |
410 | if (!usermodehelper_disabled) | |
411 | break; | |
412 | ||
413 | up_read(&umhelper_sem); | |
414 | ||
415 | timeout = schedule_timeout(timeout); | |
416 | if (!timeout) | |
417 | break; | |
418 | ||
419 | down_read(&umhelper_sem); | |
420 | } | |
421 | finish_wait(&usermodehelper_disabled_waitq, &wait); | |
422 | return timeout; | |
423 | } | |
424 | EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait); | |
425 | ||
fe2e39d8 | 426 | void usermodehelper_read_unlock(void) |
b298d289 SB |
427 | { |
428 | up_read(&umhelper_sem); | |
429 | } | |
fe2e39d8 | 430 | EXPORT_SYMBOL_GPL(usermodehelper_read_unlock); |
b298d289 | 431 | |
9b78c1da | 432 | /** |
247bc037 | 433 | * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled. |
9b3c98cd | 434 | * @depth: New value to assign to usermodehelper_disabled. |
247bc037 RW |
435 | * |
436 | * Change the value of usermodehelper_disabled (under umhelper_sem locked for | |
437 | * writing) and wakeup tasks waiting for it to change. | |
9b78c1da | 438 | */ |
247bc037 | 439 | void __usermodehelper_set_disable_depth(enum umh_disable_depth depth) |
9b78c1da RW |
440 | { |
441 | down_write(&umhelper_sem); | |
247bc037 | 442 | usermodehelper_disabled = depth; |
9b78c1da RW |
443 | wake_up(&usermodehelper_disabled_waitq); |
444 | up_write(&umhelper_sem); | |
445 | } | |
446 | ||
1bfcf130 | 447 | /** |
247bc037 RW |
448 | * __usermodehelper_disable - Prevent new helpers from being started. |
449 | * @depth: New value to assign to usermodehelper_disabled. | |
450 | * | |
451 | * Set usermodehelper_disabled to @depth and wait for running helpers to exit. | |
1bfcf130 | 452 | */ |
247bc037 | 453 | int __usermodehelper_disable(enum umh_disable_depth depth) |
8cdd4936 | 454 | { |
ccd4b65a RW |
455 | long retval; |
456 | ||
247bc037 RW |
457 | if (!depth) |
458 | return -EINVAL; | |
459 | ||
b298d289 | 460 | down_write(&umhelper_sem); |
247bc037 | 461 | usermodehelper_disabled = depth; |
b298d289 SB |
462 | up_write(&umhelper_sem); |
463 | ||
1bfcf130 RW |
464 | /* |
465 | * From now on call_usermodehelper_exec() won't start any new | |
466 | * helpers, so it is sufficient if running_helpers turns out to | |
467 | * be zero at one point (it may be increased later, but that | |
468 | * doesn't matter). | |
469 | */ | |
470 | retval = wait_event_timeout(running_helpers_waitq, | |
ccd4b65a RW |
471 | atomic_read(&running_helpers) == 0, |
472 | RUNNING_HELPERS_TIMEOUT); | |
1bfcf130 RW |
473 | if (retval) |
474 | return 0; | |
8cdd4936 | 475 | |
247bc037 | 476 | __usermodehelper_set_disable_depth(UMH_ENABLED); |
1bfcf130 RW |
477 | return -EAGAIN; |
478 | } | |
479 | ||
ccd4b65a RW |
480 | static void helper_lock(void) |
481 | { | |
482 | atomic_inc(&running_helpers); | |
4e857c58 | 483 | smp_mb__after_atomic(); |
ccd4b65a RW |
484 | } |
485 | ||
486 | static void helper_unlock(void) | |
487 | { | |
488 | if (atomic_dec_and_test(&running_helpers)) | |
489 | wake_up(&running_helpers_waitq); | |
490 | } | |
ccd4b65a | 491 | |
1da177e4 | 492 | /** |
0ab4dc92 | 493 | * call_usermodehelper_setup - prepare to call a usermode helper |
61df47c8 RD |
494 | * @path: path to usermode executable |
495 | * @argv: arg vector for process | |
496 | * @envp: environment for process | |
ac331d15 | 497 | * @gfp_mask: gfp mask for memory allocation |
938e4b22 LDM |
498 | * @cleanup: a cleanup function |
499 | * @init: an init function | |
500 | * @data: arbitrary context sensitive data | |
0ab4dc92 | 501 | * |
61df47c8 | 502 | * Returns either %NULL on allocation failure, or a subprocess_info |
0ab4dc92 JF |
503 | * structure. This should be passed to call_usermodehelper_exec to |
504 | * exec the process and free the structure. | |
938e4b22 LDM |
505 | * |
506 | * The init function is used to customize the helper process prior to | |
507 | * exec. A non-zero return code causes the process to error out, exit, | |
508 | * and return the failure to the calling process | |
509 | * | |
510 | * The cleanup function is just before ethe subprocess_info is about to | |
511 | * be freed. This can be used for freeing the argv and envp. The | |
512 | * Function must be runnable in either a process context or the | |
513 | * context in which call_usermodehelper_exec is called. | |
0ab4dc92 | 514 | */ |
ac331d15 | 515 | struct subprocess_info *call_usermodehelper_setup(char *path, char **argv, |
938e4b22 LDM |
516 | char **envp, gfp_t gfp_mask, |
517 | int (*init)(struct subprocess_info *info, struct cred *new), | |
518 | void (*cleanup)(struct subprocess_info *info), | |
519 | void *data) | |
0ab4dc92 JF |
520 | { |
521 | struct subprocess_info *sub_info; | |
ac331d15 | 522 | sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask); |
0ab4dc92 JF |
523 | if (!sub_info) |
524 | goto out; | |
525 | ||
b6b50a81 | 526 | INIT_WORK(&sub_info->work, call_usermodehelper_exec_work); |
0ab4dc92 JF |
527 | sub_info->path = path; |
528 | sub_info->argv = argv; | |
529 | sub_info->envp = envp; | |
938e4b22 LDM |
530 | |
531 | sub_info->cleanup = cleanup; | |
532 | sub_info->init = init; | |
533 | sub_info->data = data; | |
0ab4dc92 JF |
534 | out: |
535 | return sub_info; | |
536 | } | |
938e4b22 | 537 | EXPORT_SYMBOL(call_usermodehelper_setup); |
0ab4dc92 | 538 | |
0ab4dc92 JF |
539 | /** |
540 | * call_usermodehelper_exec - start a usermode application | |
541 | * @sub_info: information about the subprocessa | |
1da177e4 | 542 | * @wait: wait for the application to finish and return status. |
66e5b7e1 LDM |
543 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back |
544 | * when the program couldn't be exec'ed. This makes it safe to call | |
a98f0dd3 | 545 | * from interrupt context. |
1da177e4 LT |
546 | * |
547 | * Runs a user-space application. The application is started | |
90f02303 FW |
548 | * asynchronously if wait is not set, and runs as a child of system workqueues. |
549 | * (ie. it runs with full root capabilities and optimized affinity). | |
1da177e4 | 550 | */ |
9d944ef3 | 551 | int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) |
1da177e4 | 552 | { |
60be6b9a | 553 | DECLARE_COMPLETION_ONSTACK(done); |
78468033 | 554 | int retval = 0; |
1da177e4 | 555 | |
4c1c7be9 TH |
556 | if (!sub_info->path) { |
557 | call_usermodehelper_freeinfo(sub_info); | |
558 | return -EINVAL; | |
559 | } | |
ccd4b65a | 560 | helper_lock(); |
90f02303 | 561 | if (usermodehelper_disabled) { |
0ab4dc92 JF |
562 | retval = -EBUSY; |
563 | goto out; | |
564 | } | |
0baf2a4d MS |
565 | /* |
566 | * Set the completion pointer only if there is a waiter. | |
567 | * This makes it possible to use umh_complete to free | |
568 | * the data structure in case of UMH_NO_WAIT. | |
569 | */ | |
570 | sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done; | |
a98f0dd3 AK |
571 | sub_info->wait = wait; |
572 | ||
90f02303 | 573 | queue_work(system_unbound_wq, &sub_info->work); |
78468033 NC |
574 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ |
575 | goto unlock; | |
d0bd587a ON |
576 | |
577 | if (wait & UMH_KILLABLE) { | |
578 | retval = wait_for_completion_killable(&done); | |
579 | if (!retval) | |
580 | goto wait_done; | |
581 | ||
582 | /* umh_complete() will see NULL and free sub_info */ | |
583 | if (xchg(&sub_info->complete, NULL)) | |
584 | goto unlock; | |
585 | /* fallthrough, umh_complete() was already called */ | |
586 | } | |
587 | ||
1da177e4 | 588 | wait_for_completion(&done); |
d0bd587a | 589 | wait_done: |
a98f0dd3 | 590 | retval = sub_info->retval; |
78468033 | 591 | out: |
0ab4dc92 | 592 | call_usermodehelper_freeinfo(sub_info); |
78468033 | 593 | unlock: |
ccd4b65a | 594 | helper_unlock(); |
a98f0dd3 | 595 | return retval; |
1da177e4 | 596 | } |
938e4b22 | 597 | EXPORT_SYMBOL(call_usermodehelper_exec); |
785042f2 | 598 | |
66e5b7e1 LDM |
599 | /** |
600 | * call_usermodehelper() - prepare and start a usermode application | |
601 | * @path: path to usermode executable | |
602 | * @argv: arg vector for process | |
603 | * @envp: environment for process | |
604 | * @wait: wait for the application to finish and return status. | |
605 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back | |
606 | * when the program couldn't be exec'ed. This makes it safe to call | |
607 | * from interrupt context. | |
608 | * | |
609 | * This function is the equivalent to use call_usermodehelper_setup() and | |
610 | * call_usermodehelper_exec(). | |
79c743dd | 611 | */ |
66e5b7e1 | 612 | int call_usermodehelper(char *path, char **argv, char **envp, int wait) |
785042f2 BH |
613 | { |
614 | struct subprocess_info *info; | |
615 | gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL; | |
616 | ||
938e4b22 | 617 | info = call_usermodehelper_setup(path, argv, envp, gfp_mask, |
66e5b7e1 | 618 | NULL, NULL, NULL); |
785042f2 BH |
619 | if (info == NULL) |
620 | return -ENOMEM; | |
621 | ||
785042f2 BH |
622 | return call_usermodehelper_exec(info, wait); |
623 | } | |
66e5b7e1 | 624 | EXPORT_SYMBOL(call_usermodehelper); |
1da177e4 | 625 | |
17f60a7d EP |
626 | static int proc_cap_handler(struct ctl_table *table, int write, |
627 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
628 | { | |
629 | struct ctl_table t; | |
630 | unsigned long cap_array[_KERNEL_CAPABILITY_U32S]; | |
631 | kernel_cap_t new_cap; | |
632 | int err, i; | |
633 | ||
634 | if (write && (!capable(CAP_SETPCAP) || | |
635 | !capable(CAP_SYS_MODULE))) | |
636 | return -EPERM; | |
637 | ||
638 | /* | |
639 | * convert from the global kernel_cap_t to the ulong array to print to | |
640 | * userspace if this is a read. | |
641 | */ | |
642 | spin_lock(&umh_sysctl_lock); | |
643 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) { | |
644 | if (table->data == CAP_BSET) | |
645 | cap_array[i] = usermodehelper_bset.cap[i]; | |
646 | else if (table->data == CAP_PI) | |
647 | cap_array[i] = usermodehelper_inheritable.cap[i]; | |
648 | else | |
649 | BUG(); | |
650 | } | |
651 | spin_unlock(&umh_sysctl_lock); | |
652 | ||
653 | t = *table; | |
654 | t.data = &cap_array; | |
655 | ||
656 | /* | |
657 | * actually read or write and array of ulongs from userspace. Remember | |
658 | * these are least significant 32 bits first | |
659 | */ | |
660 | err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); | |
661 | if (err < 0) | |
662 | return err; | |
663 | ||
664 | /* | |
665 | * convert from the sysctl array of ulongs to the kernel_cap_t | |
666 | * internal representation | |
667 | */ | |
668 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) | |
669 | new_cap.cap[i] = cap_array[i]; | |
670 | ||
671 | /* | |
672 | * Drop everything not in the new_cap (but don't add things) | |
673 | */ | |
674 | spin_lock(&umh_sysctl_lock); | |
675 | if (write) { | |
676 | if (table->data == CAP_BSET) | |
677 | usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap); | |
678 | if (table->data == CAP_PI) | |
679 | usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap); | |
680 | } | |
681 | spin_unlock(&umh_sysctl_lock); | |
682 | ||
683 | return 0; | |
684 | } | |
685 | ||
686 | struct ctl_table usermodehelper_table[] = { | |
687 | { | |
688 | .procname = "bset", | |
689 | .data = CAP_BSET, | |
690 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
691 | .mode = 0600, | |
692 | .proc_handler = proc_cap_handler, | |
693 | }, | |
694 | { | |
695 | .procname = "inheritable", | |
696 | .data = CAP_PI, | |
697 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
698 | .mode = 0600, | |
699 | .proc_handler = proc_cap_handler, | |
700 | }, | |
701 | { } | |
702 | }; |