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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> | |
29930025 | 23 | #include <linux/sched/task.h> |
5c2c5c55 | 24 | #include <linux/binfmts.h> |
1da177e4 LT |
25 | #include <linux/syscalls.h> |
26 | #include <linux/unistd.h> | |
27 | #include <linux/kmod.h> | |
1da177e4 | 28 | #include <linux/slab.h> |
1da177e4 | 29 | #include <linux/completion.h> |
17f60a7d | 30 | #include <linux/cred.h> |
1da177e4 | 31 | #include <linux/file.h> |
9f3acc31 | 32 | #include <linux/fdtable.h> |
1da177e4 LT |
33 | #include <linux/workqueue.h> |
34 | #include <linux/security.h> | |
35 | #include <linux/mount.h> | |
36 | #include <linux/kernel.h> | |
37 | #include <linux/init.h> | |
d025c9db | 38 | #include <linux/resource.h> |
8cdd4936 RW |
39 | #include <linux/notifier.h> |
40 | #include <linux/suspend.h> | |
b298d289 | 41 | #include <linux/rwsem.h> |
a74fb73c | 42 | #include <linux/ptrace.h> |
0fdff3ec | 43 | #include <linux/async.h> |
7c0f6ba6 | 44 | #include <linux/uaccess.h> |
1da177e4 | 45 | |
7ead8b83 LZ |
46 | #include <trace/events/module.h> |
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 |
165d1cc0 LR |
57 | /* |
58 | * Assuming: | |
59 | * | |
60 | * threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE, | |
61 | * (u64) THREAD_SIZE * 8UL); | |
62 | * | |
63 | * If you need less than 50 threads would mean we're dealing with systems | |
64 | * smaller than 3200 pages. This assuems you are capable of having ~13M memory, | |
65 | * and this would only be an be an upper limit, after which the OOM killer | |
66 | * would take effect. Systems like these are very unlikely if modules are | |
67 | * enabled. | |
68 | */ | |
69 | #define MAX_KMOD_CONCURRENT 50 | |
70 | static atomic_t kmod_concurrent_max = ATOMIC_INIT(MAX_KMOD_CONCURRENT); | |
1da177e4 LT |
71 | |
72 | /* | |
73 | modprobe_path is set via /proc/sys. | |
74 | */ | |
75 | char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe"; | |
76 | ||
1cc684ab ON |
77 | static void free_modprobe_argv(struct subprocess_info *info) |
78 | { | |
79 | kfree(info->argv[3]); /* check call_modprobe() */ | |
80 | kfree(info->argv); | |
81 | } | |
82 | ||
3e63a93b ON |
83 | static int call_modprobe(char *module_name, int wait) |
84 | { | |
f634460c | 85 | struct subprocess_info *info; |
3e63a93b ON |
86 | static char *envp[] = { |
87 | "HOME=/", | |
88 | "TERM=linux", | |
89 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
90 | NULL | |
91 | }; | |
92 | ||
1cc684ab ON |
93 | char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL); |
94 | if (!argv) | |
95 | goto out; | |
96 | ||
97 | module_name = kstrdup(module_name, GFP_KERNEL); | |
98 | if (!module_name) | |
99 | goto free_argv; | |
100 | ||
101 | argv[0] = modprobe_path; | |
102 | argv[1] = "-q"; | |
103 | argv[2] = "--"; | |
104 | argv[3] = module_name; /* check free_modprobe_argv() */ | |
105 | argv[4] = NULL; | |
3e63a93b | 106 | |
f634460c LDM |
107 | info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL, |
108 | NULL, free_modprobe_argv, NULL); | |
109 | if (!info) | |
110 | goto free_module_name; | |
111 | ||
112 | return call_usermodehelper_exec(info, wait | UMH_KILLABLE); | |
113 | ||
114 | free_module_name: | |
115 | kfree(module_name); | |
1cc684ab ON |
116 | free_argv: |
117 | kfree(argv); | |
118 | out: | |
119 | return -ENOMEM; | |
3e63a93b ON |
120 | } |
121 | ||
1da177e4 | 122 | /** |
acae0515 AV |
123 | * __request_module - try to load a kernel module |
124 | * @wait: wait (or not) for the operation to complete | |
bd4207c9 RD |
125 | * @fmt: printf style format string for the name of the module |
126 | * @...: arguments as specified in the format string | |
1da177e4 LT |
127 | * |
128 | * Load a module using the user mode module loader. The function returns | |
60b61a6f N |
129 | * zero on success or a negative errno code or positive exit code from |
130 | * "modprobe" on failure. Note that a successful module load does not mean | |
131 | * the module did not then unload and exit on an error of its own. Callers | |
132 | * must check that the service they requested is now available not blindly | |
133 | * invoke it. | |
1da177e4 LT |
134 | * |
135 | * If module auto-loading support is disabled then this function | |
136 | * becomes a no-operation. | |
137 | */ | |
acae0515 | 138 | int __request_module(bool wait, const char *fmt, ...) |
1da177e4 LT |
139 | { |
140 | va_list args; | |
141 | char module_name[MODULE_NAME_LEN]; | |
1da177e4 | 142 | int ret; |
1da177e4 LT |
143 | static int kmod_loop_msg; |
144 | ||
0fdff3ec TH |
145 | /* |
146 | * We don't allow synchronous module loading from async. Module | |
147 | * init may invoke async_synchronize_full() which will end up | |
148 | * waiting for this task which already is waiting for the module | |
149 | * loading to complete, leading to a deadlock. | |
150 | */ | |
151 | WARN_ON_ONCE(wait && current_is_async()); | |
152 | ||
7f57cfa4 ON |
153 | if (!modprobe_path[0]) |
154 | return 0; | |
155 | ||
1da177e4 LT |
156 | va_start(args, fmt); |
157 | ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args); | |
158 | va_end(args); | |
159 | if (ret >= MODULE_NAME_LEN) | |
160 | return -ENAMETOOLONG; | |
161 | ||
dd8dbf2e EP |
162 | ret = security_kernel_module_request(module_name); |
163 | if (ret) | |
164 | return ret; | |
165 | ||
165d1cc0 | 166 | if (atomic_dec_if_positive(&kmod_concurrent_max) < 0) { |
1da177e4 | 167 | /* We may be blaming an innocent here, but unlikely */ |
37252db6 | 168 | if (kmod_loop_msg < 5) { |
1da177e4 LT |
169 | printk(KERN_ERR |
170 | "request_module: runaway loop modprobe %s\n", | |
171 | module_name); | |
37252db6 JK |
172 | kmod_loop_msg++; |
173 | } | |
1da177e4 LT |
174 | return -ENOMEM; |
175 | } | |
176 | ||
7ead8b83 LZ |
177 | trace_module_request(module_name, wait, _RET_IP_); |
178 | ||
3e63a93b | 179 | ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC); |
a06a4dc3 | 180 | |
165d1cc0 LR |
181 | atomic_inc(&kmod_concurrent_max); |
182 | ||
1da177e4 LT |
183 | return ret; |
184 | } | |
acae0515 | 185 | EXPORT_SYMBOL(__request_module); |
165d1cc0 | 186 | |
118a9069 | 187 | #endif /* CONFIG_MODULES */ |
1da177e4 | 188 | |
0baf2a4d MS |
189 | static void call_usermodehelper_freeinfo(struct subprocess_info *info) |
190 | { | |
191 | if (info->cleanup) | |
192 | (*info->cleanup)(info); | |
193 | kfree(info); | |
194 | } | |
195 | ||
196 | static void umh_complete(struct subprocess_info *sub_info) | |
197 | { | |
198 | struct completion *comp = xchg(&sub_info->complete, NULL); | |
199 | /* | |
200 | * See call_usermodehelper_exec(). If xchg() returns NULL | |
201 | * we own sub_info, the UMH_KILLABLE caller has gone away | |
202 | * or the caller used UMH_NO_WAIT. | |
203 | */ | |
204 | if (comp) | |
205 | complete(comp); | |
206 | else | |
207 | call_usermodehelper_freeinfo(sub_info); | |
208 | } | |
209 | ||
1da177e4 LT |
210 | /* |
211 | * This is the task which runs the usermode application | |
212 | */ | |
b6b50a81 | 213 | static int call_usermodehelper_exec_async(void *data) |
1da177e4 LT |
214 | { |
215 | struct subprocess_info *sub_info = data; | |
17f60a7d | 216 | struct cred *new; |
1da177e4 LT |
217 | int retval; |
218 | ||
1da177e4 LT |
219 | spin_lock_irq(¤t->sighand->siglock); |
220 | flush_signal_handlers(current, 1); | |
1da177e4 LT |
221 | spin_unlock_irq(¤t->sighand->siglock); |
222 | ||
b73a7e76 | 223 | /* |
90f02303 | 224 | * Our parent (unbound workqueue) runs with elevated scheduling |
b639e86b | 225 | * priority. Avoid propagating that into the userspace child. |
b73a7e76 JE |
226 | */ |
227 | set_user_nice(current, 0); | |
228 | ||
17f60a7d EP |
229 | retval = -ENOMEM; |
230 | new = prepare_kernel_cred(current); | |
231 | if (!new) | |
0baf2a4d | 232 | goto out; |
17f60a7d EP |
233 | |
234 | spin_lock(&umh_sysctl_lock); | |
235 | new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset); | |
236 | new->cap_inheritable = cap_intersect(usermodehelper_inheritable, | |
237 | new->cap_inheritable); | |
238 | spin_unlock(&umh_sysctl_lock); | |
239 | ||
87966996 DH |
240 | if (sub_info->init) { |
241 | retval = sub_info->init(sub_info, new); | |
242 | if (retval) { | |
243 | abort_creds(new); | |
0baf2a4d | 244 | goto out; |
87966996 DH |
245 | } |
246 | } | |
247 | ||
17f60a7d EP |
248 | commit_creds(new); |
249 | ||
c4ad8f98 | 250 | retval = do_execve(getname_kernel(sub_info->path), |
ae903caa AV |
251 | (const char __user *const __user *)sub_info->argv, |
252 | (const char __user *const __user *)sub_info->envp); | |
0baf2a4d MS |
253 | out: |
254 | sub_info->retval = retval; | |
b6b50a81 FW |
255 | /* |
256 | * call_usermodehelper_exec_sync() will call umh_complete | |
257 | * if UHM_WAIT_PROC. | |
258 | */ | |
7117bc88 | 259 | if (!(sub_info->wait & UMH_WAIT_PROC)) |
0baf2a4d | 260 | umh_complete(sub_info); |
a74fb73c AV |
261 | if (!retval) |
262 | return 0; | |
fb45550d | 263 | do_exit(0); |
1da177e4 LT |
264 | } |
265 | ||
bb304a5c FW |
266 | /* Handles UMH_WAIT_PROC. */ |
267 | static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info) | |
1da177e4 | 268 | { |
1da177e4 | 269 | pid_t pid; |
1da177e4 | 270 | |
7d642242 | 271 | /* If SIGCLD is ignored sys_wait4 won't populate the status. */ |
76e0a6f4 | 272 | kernel_sigaction(SIGCHLD, SIG_DFL); |
b6b50a81 | 273 | pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD); |
1da177e4 LT |
274 | if (pid < 0) { |
275 | sub_info->retval = pid; | |
276 | } else { | |
7d642242 | 277 | int ret = -ECHILD; |
1da177e4 LT |
278 | /* |
279 | * Normally it is bogus to call wait4() from in-kernel because | |
280 | * wait4() wants to write the exit code to a userspace address. | |
b639e86b | 281 | * But call_usermodehelper_exec_sync() always runs as kernel |
bb304a5c FW |
282 | * thread (workqueue) and put_user() to a kernel address works |
283 | * OK for kernel threads, due to their having an mm_segment_t | |
284 | * which spans the entire address space. | |
1da177e4 LT |
285 | * |
286 | * Thus the __user pointer cast is valid here. | |
287 | */ | |
111dbe0c BS |
288 | sys_wait4(pid, (int __user *)&ret, 0, NULL); |
289 | ||
290 | /* | |
b6b50a81 FW |
291 | * If ret is 0, either call_usermodehelper_exec_async failed and |
292 | * the real error code is already in sub_info->retval or | |
111dbe0c BS |
293 | * sub_info->retval is 0 anyway, so don't mess with it then. |
294 | */ | |
295 | if (ret) | |
296 | sub_info->retval = ret; | |
1da177e4 LT |
297 | } |
298 | ||
bb304a5c FW |
299 | /* Restore default kernel sig handler */ |
300 | kernel_sigaction(SIGCHLD, SIG_IGN); | |
301 | ||
b3449922 | 302 | umh_complete(sub_info); |
1da177e4 LT |
303 | } |
304 | ||
b639e86b | 305 | /* |
bb304a5c | 306 | * We need to create the usermodehelper kernel thread from a task that is affine |
90f02303 FW |
307 | * to an optimized set of CPUs (or nohz housekeeping ones) such that they |
308 | * inherit a widest affinity irrespective of call_usermodehelper() callers with | |
309 | * possibly reduced affinity (eg: per-cpu workqueues). We don't want | |
310 | * usermodehelper targets to contend a busy CPU. | |
311 | * | |
bb304a5c FW |
312 | * Unbound workqueues provide such wide affinity and allow to block on |
313 | * UMH_WAIT_PROC requests without blocking pending request (up to some limit). | |
b639e86b | 314 | * |
90f02303 FW |
315 | * Besides, workqueues provide the privilege level that caller might not have |
316 | * to perform the usermodehelper request. | |
b639e86b FW |
317 | * |
318 | */ | |
b6b50a81 | 319 | static void call_usermodehelper_exec_work(struct work_struct *work) |
1da177e4 | 320 | { |
65f27f38 DH |
321 | struct subprocess_info *sub_info = |
322 | container_of(work, struct subprocess_info, work); | |
1da177e4 | 323 | |
bb304a5c FW |
324 | if (sub_info->wait & UMH_WAIT_PROC) { |
325 | call_usermodehelper_exec_sync(sub_info); | |
326 | } else { | |
327 | pid_t pid; | |
52116139 ON |
328 | /* |
329 | * Use CLONE_PARENT to reparent it to kthreadd; we do not | |
330 | * want to pollute current->children, and we need a parent | |
331 | * that always ignores SIGCHLD to ensure auto-reaping. | |
332 | */ | |
b6b50a81 | 333 | pid = kernel_thread(call_usermodehelper_exec_async, sub_info, |
52116139 | 334 | CLONE_PARENT | SIGCHLD); |
bb304a5c FW |
335 | if (pid < 0) { |
336 | sub_info->retval = pid; | |
337 | umh_complete(sub_info); | |
338 | } | |
86313c48 | 339 | } |
1da177e4 LT |
340 | } |
341 | ||
ccd4b65a RW |
342 | /* |
343 | * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY | |
344 | * (used for preventing user land processes from being created after the user | |
345 | * land has been frozen during a system-wide hibernation or suspend operation). | |
b298d289 | 346 | * Should always be manipulated under umhelper_sem acquired for write. |
ccd4b65a | 347 | */ |
247bc037 | 348 | static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED; |
ccd4b65a RW |
349 | |
350 | /* Number of helpers running */ | |
351 | static atomic_t running_helpers = ATOMIC_INIT(0); | |
352 | ||
353 | /* | |
5307427a | 354 | * Wait queue head used by usermodehelper_disable() to wait for all running |
ccd4b65a RW |
355 | * helpers to finish. |
356 | */ | |
357 | static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); | |
358 | ||
9b78c1da RW |
359 | /* |
360 | * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled | |
361 | * to become 'false'. | |
362 | */ | |
363 | static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq); | |
364 | ||
ccd4b65a RW |
365 | /* |
366 | * Time to wait for running_helpers to become zero before the setting of | |
5307427a | 367 | * usermodehelper_disabled in usermodehelper_disable() fails |
ccd4b65a RW |
368 | */ |
369 | #define RUNNING_HELPERS_TIMEOUT (5 * HZ) | |
370 | ||
fe2e39d8 | 371 | int usermodehelper_read_trylock(void) |
b298d289 | 372 | { |
247bc037 | 373 | DEFINE_WAIT(wait); |
fe2e39d8 RW |
374 | int ret = 0; |
375 | ||
b298d289 | 376 | down_read(&umhelper_sem); |
247bc037 RW |
377 | for (;;) { |
378 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
379 | TASK_INTERRUPTIBLE); | |
380 | if (!usermodehelper_disabled) | |
381 | break; | |
382 | ||
383 | if (usermodehelper_disabled == UMH_DISABLED) | |
384 | ret = -EAGAIN; | |
385 | ||
fe2e39d8 | 386 | up_read(&umhelper_sem); |
247bc037 RW |
387 | |
388 | if (ret) | |
389 | break; | |
390 | ||
391 | schedule(); | |
392 | try_to_freeze(); | |
393 | ||
394 | down_read(&umhelper_sem); | |
fe2e39d8 | 395 | } |
247bc037 | 396 | finish_wait(&usermodehelper_disabled_waitq, &wait); |
fe2e39d8 | 397 | return ret; |
b298d289 | 398 | } |
fe2e39d8 | 399 | EXPORT_SYMBOL_GPL(usermodehelper_read_trylock); |
b298d289 | 400 | |
9b78c1da RW |
401 | long usermodehelper_read_lock_wait(long timeout) |
402 | { | |
403 | DEFINE_WAIT(wait); | |
404 | ||
405 | if (timeout < 0) | |
406 | return -EINVAL; | |
407 | ||
408 | down_read(&umhelper_sem); | |
409 | for (;;) { | |
410 | prepare_to_wait(&usermodehelper_disabled_waitq, &wait, | |
411 | TASK_UNINTERRUPTIBLE); | |
412 | if (!usermodehelper_disabled) | |
413 | break; | |
414 | ||
415 | up_read(&umhelper_sem); | |
416 | ||
417 | timeout = schedule_timeout(timeout); | |
418 | if (!timeout) | |
419 | break; | |
420 | ||
421 | down_read(&umhelper_sem); | |
422 | } | |
423 | finish_wait(&usermodehelper_disabled_waitq, &wait); | |
424 | return timeout; | |
425 | } | |
426 | EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait); | |
427 | ||
fe2e39d8 | 428 | void usermodehelper_read_unlock(void) |
b298d289 SB |
429 | { |
430 | up_read(&umhelper_sem); | |
431 | } | |
fe2e39d8 | 432 | EXPORT_SYMBOL_GPL(usermodehelper_read_unlock); |
b298d289 | 433 | |
9b78c1da | 434 | /** |
247bc037 | 435 | * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled. |
9b3c98cd | 436 | * @depth: New value to assign to usermodehelper_disabled. |
247bc037 RW |
437 | * |
438 | * Change the value of usermodehelper_disabled (under umhelper_sem locked for | |
439 | * writing) and wakeup tasks waiting for it to change. | |
9b78c1da | 440 | */ |
247bc037 | 441 | void __usermodehelper_set_disable_depth(enum umh_disable_depth depth) |
9b78c1da RW |
442 | { |
443 | down_write(&umhelper_sem); | |
247bc037 | 444 | usermodehelper_disabled = depth; |
9b78c1da RW |
445 | wake_up(&usermodehelper_disabled_waitq); |
446 | up_write(&umhelper_sem); | |
447 | } | |
448 | ||
1bfcf130 | 449 | /** |
247bc037 RW |
450 | * __usermodehelper_disable - Prevent new helpers from being started. |
451 | * @depth: New value to assign to usermodehelper_disabled. | |
452 | * | |
453 | * Set usermodehelper_disabled to @depth and wait for running helpers to exit. | |
1bfcf130 | 454 | */ |
247bc037 | 455 | int __usermodehelper_disable(enum umh_disable_depth depth) |
8cdd4936 | 456 | { |
ccd4b65a RW |
457 | long retval; |
458 | ||
247bc037 RW |
459 | if (!depth) |
460 | return -EINVAL; | |
461 | ||
b298d289 | 462 | down_write(&umhelper_sem); |
247bc037 | 463 | usermodehelper_disabled = depth; |
b298d289 SB |
464 | up_write(&umhelper_sem); |
465 | ||
1bfcf130 RW |
466 | /* |
467 | * From now on call_usermodehelper_exec() won't start any new | |
468 | * helpers, so it is sufficient if running_helpers turns out to | |
469 | * be zero at one point (it may be increased later, but that | |
470 | * doesn't matter). | |
471 | */ | |
472 | retval = wait_event_timeout(running_helpers_waitq, | |
ccd4b65a RW |
473 | atomic_read(&running_helpers) == 0, |
474 | RUNNING_HELPERS_TIMEOUT); | |
1bfcf130 RW |
475 | if (retval) |
476 | return 0; | |
8cdd4936 | 477 | |
247bc037 | 478 | __usermodehelper_set_disable_depth(UMH_ENABLED); |
1bfcf130 RW |
479 | return -EAGAIN; |
480 | } | |
481 | ||
ccd4b65a RW |
482 | static void helper_lock(void) |
483 | { | |
484 | atomic_inc(&running_helpers); | |
4e857c58 | 485 | smp_mb__after_atomic(); |
ccd4b65a RW |
486 | } |
487 | ||
488 | static void helper_unlock(void) | |
489 | { | |
490 | if (atomic_dec_and_test(&running_helpers)) | |
491 | wake_up(&running_helpers_waitq); | |
492 | } | |
ccd4b65a | 493 | |
1da177e4 | 494 | /** |
0ab4dc92 | 495 | * call_usermodehelper_setup - prepare to call a usermode helper |
61df47c8 RD |
496 | * @path: path to usermode executable |
497 | * @argv: arg vector for process | |
498 | * @envp: environment for process | |
ac331d15 | 499 | * @gfp_mask: gfp mask for memory allocation |
938e4b22 LDM |
500 | * @cleanup: a cleanup function |
501 | * @init: an init function | |
502 | * @data: arbitrary context sensitive data | |
0ab4dc92 | 503 | * |
61df47c8 | 504 | * Returns either %NULL on allocation failure, or a subprocess_info |
0ab4dc92 JF |
505 | * structure. This should be passed to call_usermodehelper_exec to |
506 | * exec the process and free the structure. | |
938e4b22 LDM |
507 | * |
508 | * The init function is used to customize the helper process prior to | |
509 | * exec. A non-zero return code causes the process to error out, exit, | |
510 | * and return the failure to the calling process | |
511 | * | |
512 | * The cleanup function is just before ethe subprocess_info is about to | |
513 | * be freed. This can be used for freeing the argv and envp. The | |
514 | * Function must be runnable in either a process context or the | |
515 | * context in which call_usermodehelper_exec is called. | |
0ab4dc92 | 516 | */ |
6d2c5d6c | 517 | struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv, |
938e4b22 LDM |
518 | char **envp, gfp_t gfp_mask, |
519 | int (*init)(struct subprocess_info *info, struct cred *new), | |
520 | void (*cleanup)(struct subprocess_info *info), | |
521 | void *data) | |
0ab4dc92 JF |
522 | { |
523 | struct subprocess_info *sub_info; | |
ac331d15 | 524 | sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask); |
0ab4dc92 JF |
525 | if (!sub_info) |
526 | goto out; | |
527 | ||
b6b50a81 | 528 | INIT_WORK(&sub_info->work, call_usermodehelper_exec_work); |
64e90a8a GKH |
529 | |
530 | #ifdef CONFIG_STATIC_USERMODEHELPER | |
531 | sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH; | |
532 | #else | |
0ab4dc92 | 533 | sub_info->path = path; |
64e90a8a | 534 | #endif |
0ab4dc92 JF |
535 | sub_info->argv = argv; |
536 | sub_info->envp = envp; | |
938e4b22 LDM |
537 | |
538 | sub_info->cleanup = cleanup; | |
539 | sub_info->init = init; | |
540 | sub_info->data = data; | |
0ab4dc92 JF |
541 | out: |
542 | return sub_info; | |
543 | } | |
938e4b22 | 544 | EXPORT_SYMBOL(call_usermodehelper_setup); |
0ab4dc92 | 545 | |
0ab4dc92 JF |
546 | /** |
547 | * call_usermodehelper_exec - start a usermode application | |
548 | * @sub_info: information about the subprocessa | |
1da177e4 | 549 | * @wait: wait for the application to finish and return status. |
66e5b7e1 LDM |
550 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back |
551 | * when the program couldn't be exec'ed. This makes it safe to call | |
a98f0dd3 | 552 | * from interrupt context. |
1da177e4 LT |
553 | * |
554 | * Runs a user-space application. The application is started | |
90f02303 FW |
555 | * asynchronously if wait is not set, and runs as a child of system workqueues. |
556 | * (ie. it runs with full root capabilities and optimized affinity). | |
1da177e4 | 557 | */ |
9d944ef3 | 558 | int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) |
1da177e4 | 559 | { |
60be6b9a | 560 | DECLARE_COMPLETION_ONSTACK(done); |
78468033 | 561 | int retval = 0; |
1da177e4 | 562 | |
4c1c7be9 TH |
563 | if (!sub_info->path) { |
564 | call_usermodehelper_freeinfo(sub_info); | |
565 | return -EINVAL; | |
566 | } | |
ccd4b65a | 567 | helper_lock(); |
90f02303 | 568 | if (usermodehelper_disabled) { |
0ab4dc92 JF |
569 | retval = -EBUSY; |
570 | goto out; | |
571 | } | |
64e90a8a GKH |
572 | |
573 | /* | |
574 | * If there is no binary for us to call, then just return and get out of | |
575 | * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and | |
576 | * disable all call_usermodehelper() calls. | |
577 | */ | |
578 | if (strlen(sub_info->path) == 0) | |
579 | goto out; | |
580 | ||
0baf2a4d MS |
581 | /* |
582 | * Set the completion pointer only if there is a waiter. | |
583 | * This makes it possible to use umh_complete to free | |
584 | * the data structure in case of UMH_NO_WAIT. | |
585 | */ | |
586 | sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done; | |
a98f0dd3 AK |
587 | sub_info->wait = wait; |
588 | ||
90f02303 | 589 | queue_work(system_unbound_wq, &sub_info->work); |
78468033 NC |
590 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ |
591 | goto unlock; | |
d0bd587a ON |
592 | |
593 | if (wait & UMH_KILLABLE) { | |
594 | retval = wait_for_completion_killable(&done); | |
595 | if (!retval) | |
596 | goto wait_done; | |
597 | ||
598 | /* umh_complete() will see NULL and free sub_info */ | |
599 | if (xchg(&sub_info->complete, NULL)) | |
600 | goto unlock; | |
601 | /* fallthrough, umh_complete() was already called */ | |
602 | } | |
603 | ||
1da177e4 | 604 | wait_for_completion(&done); |
d0bd587a | 605 | wait_done: |
a98f0dd3 | 606 | retval = sub_info->retval; |
78468033 | 607 | out: |
0ab4dc92 | 608 | call_usermodehelper_freeinfo(sub_info); |
78468033 | 609 | unlock: |
ccd4b65a | 610 | helper_unlock(); |
a98f0dd3 | 611 | return retval; |
1da177e4 | 612 | } |
938e4b22 | 613 | EXPORT_SYMBOL(call_usermodehelper_exec); |
785042f2 | 614 | |
66e5b7e1 LDM |
615 | /** |
616 | * call_usermodehelper() - prepare and start a usermode application | |
617 | * @path: path to usermode executable | |
618 | * @argv: arg vector for process | |
619 | * @envp: environment for process | |
620 | * @wait: wait for the application to finish and return status. | |
621 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back | |
622 | * when the program couldn't be exec'ed. This makes it safe to call | |
623 | * from interrupt context. | |
624 | * | |
625 | * This function is the equivalent to use call_usermodehelper_setup() and | |
626 | * call_usermodehelper_exec(). | |
79c743dd | 627 | */ |
6d2c5d6c | 628 | int call_usermodehelper(const char *path, char **argv, char **envp, int wait) |
785042f2 BH |
629 | { |
630 | struct subprocess_info *info; | |
631 | gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL; | |
632 | ||
938e4b22 | 633 | info = call_usermodehelper_setup(path, argv, envp, gfp_mask, |
66e5b7e1 | 634 | NULL, NULL, NULL); |
785042f2 BH |
635 | if (info == NULL) |
636 | return -ENOMEM; | |
637 | ||
785042f2 BH |
638 | return call_usermodehelper_exec(info, wait); |
639 | } | |
66e5b7e1 | 640 | EXPORT_SYMBOL(call_usermodehelper); |
1da177e4 | 641 | |
17f60a7d EP |
642 | static int proc_cap_handler(struct ctl_table *table, int write, |
643 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
644 | { | |
645 | struct ctl_table t; | |
646 | unsigned long cap_array[_KERNEL_CAPABILITY_U32S]; | |
647 | kernel_cap_t new_cap; | |
648 | int err, i; | |
649 | ||
650 | if (write && (!capable(CAP_SETPCAP) || | |
651 | !capable(CAP_SYS_MODULE))) | |
652 | return -EPERM; | |
653 | ||
654 | /* | |
655 | * convert from the global kernel_cap_t to the ulong array to print to | |
656 | * userspace if this is a read. | |
657 | */ | |
658 | spin_lock(&umh_sysctl_lock); | |
659 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) { | |
660 | if (table->data == CAP_BSET) | |
661 | cap_array[i] = usermodehelper_bset.cap[i]; | |
662 | else if (table->data == CAP_PI) | |
663 | cap_array[i] = usermodehelper_inheritable.cap[i]; | |
664 | else | |
665 | BUG(); | |
666 | } | |
667 | spin_unlock(&umh_sysctl_lock); | |
668 | ||
669 | t = *table; | |
670 | t.data = &cap_array; | |
671 | ||
672 | /* | |
673 | * actually read or write and array of ulongs from userspace. Remember | |
674 | * these are least significant 32 bits first | |
675 | */ | |
676 | err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); | |
677 | if (err < 0) | |
678 | return err; | |
679 | ||
680 | /* | |
681 | * convert from the sysctl array of ulongs to the kernel_cap_t | |
682 | * internal representation | |
683 | */ | |
684 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) | |
685 | new_cap.cap[i] = cap_array[i]; | |
686 | ||
687 | /* | |
688 | * Drop everything not in the new_cap (but don't add things) | |
689 | */ | |
690 | spin_lock(&umh_sysctl_lock); | |
691 | if (write) { | |
692 | if (table->data == CAP_BSET) | |
693 | usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap); | |
694 | if (table->data == CAP_PI) | |
695 | usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap); | |
696 | } | |
697 | spin_unlock(&umh_sysctl_lock); | |
698 | ||
699 | return 0; | |
700 | } | |
701 | ||
702 | struct ctl_table usermodehelper_table[] = { | |
703 | { | |
704 | .procname = "bset", | |
705 | .data = CAP_BSET, | |
706 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
707 | .mode = 0600, | |
708 | .proc_handler = proc_cap_handler, | |
709 | }, | |
710 | { | |
711 | .procname = "inheritable", | |
712 | .data = CAP_PI, | |
713 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
714 | .mode = 0600, | |
715 | .proc_handler = proc_cap_handler, | |
716 | }, | |
717 | { } | |
718 | }; |