]>
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> | |
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); | |
6d7964a7 | 71 | static DECLARE_WAIT_QUEUE_HEAD(kmod_wq); |
1da177e4 LT |
72 | |
73 | /* | |
74 | modprobe_path is set via /proc/sys. | |
75 | */ | |
76 | char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe"; | |
77 | ||
1cc684ab ON |
78 | static void free_modprobe_argv(struct subprocess_info *info) |
79 | { | |
80 | kfree(info->argv[3]); /* check call_modprobe() */ | |
81 | kfree(info->argv); | |
82 | } | |
83 | ||
3e63a93b ON |
84 | static int call_modprobe(char *module_name, int wait) |
85 | { | |
f634460c | 86 | struct subprocess_info *info; |
3e63a93b ON |
87 | static char *envp[] = { |
88 | "HOME=/", | |
89 | "TERM=linux", | |
90 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
91 | NULL | |
92 | }; | |
93 | ||
1cc684ab ON |
94 | char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL); |
95 | if (!argv) | |
96 | goto out; | |
97 | ||
98 | module_name = kstrdup(module_name, GFP_KERNEL); | |
99 | if (!module_name) | |
100 | goto free_argv; | |
101 | ||
102 | argv[0] = modprobe_path; | |
103 | argv[1] = "-q"; | |
104 | argv[2] = "--"; | |
105 | argv[3] = module_name; /* check free_modprobe_argv() */ | |
106 | argv[4] = NULL; | |
3e63a93b | 107 | |
f634460c LDM |
108 | info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL, |
109 | NULL, free_modprobe_argv, NULL); | |
110 | if (!info) | |
111 | goto free_module_name; | |
112 | ||
113 | return call_usermodehelper_exec(info, wait | UMH_KILLABLE); | |
114 | ||
115 | free_module_name: | |
116 | kfree(module_name); | |
1cc684ab ON |
117 | free_argv: |
118 | kfree(argv); | |
119 | out: | |
120 | return -ENOMEM; | |
3e63a93b ON |
121 | } |
122 | ||
1da177e4 | 123 | /** |
acae0515 AV |
124 | * __request_module - try to load a kernel module |
125 | * @wait: wait (or not) for the operation to complete | |
bd4207c9 RD |
126 | * @fmt: printf style format string for the name of the module |
127 | * @...: arguments as specified in the format string | |
1da177e4 LT |
128 | * |
129 | * Load a module using the user mode module loader. The function returns | |
60b61a6f N |
130 | * zero on success or a negative errno code or positive exit code from |
131 | * "modprobe" on failure. Note that a successful module load does not mean | |
132 | * the module did not then unload and exit on an error of its own. Callers | |
133 | * must check that the service they requested is now available not blindly | |
134 | * invoke it. | |
1da177e4 LT |
135 | * |
136 | * If module auto-loading support is disabled then this function | |
137 | * becomes a no-operation. | |
138 | */ | |
acae0515 | 139 | int __request_module(bool wait, const char *fmt, ...) |
1da177e4 LT |
140 | { |
141 | va_list args; | |
142 | char module_name[MODULE_NAME_LEN]; | |
1da177e4 | 143 | int ret; |
1da177e4 | 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) { |
6d7964a7 LR |
167 | pr_warn_ratelimited("request_module: kmod_concurrent_max (%u) close to 0 (max_modprobes: %u), for module %s, throttling...", |
168 | atomic_read(&kmod_concurrent_max), | |
169 | MAX_KMOD_CONCURRENT, module_name); | |
170 | wait_event_interruptible(kmod_wq, | |
171 | atomic_dec_if_positive(&kmod_concurrent_max) >= 0); | |
1da177e4 LT |
172 | } |
173 | ||
7ead8b83 LZ |
174 | trace_module_request(module_name, wait, _RET_IP_); |
175 | ||
3e63a93b | 176 | ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC); |
a06a4dc3 | 177 | |
165d1cc0 | 178 | atomic_inc(&kmod_concurrent_max); |
6d7964a7 | 179 | wake_up(&kmod_wq); |
165d1cc0 | 180 | |
1da177e4 LT |
181 | return ret; |
182 | } | |
acae0515 | 183 | EXPORT_SYMBOL(__request_module); |
165d1cc0 | 184 | |
118a9069 | 185 | #endif /* CONFIG_MODULES */ |
1da177e4 | 186 | |
0baf2a4d MS |
187 | static void call_usermodehelper_freeinfo(struct subprocess_info *info) |
188 | { | |
189 | if (info->cleanup) | |
190 | (*info->cleanup)(info); | |
191 | kfree(info); | |
192 | } | |
193 | ||
194 | static void umh_complete(struct subprocess_info *sub_info) | |
195 | { | |
196 | struct completion *comp = xchg(&sub_info->complete, NULL); | |
197 | /* | |
198 | * See call_usermodehelper_exec(). If xchg() returns NULL | |
199 | * we own sub_info, the UMH_KILLABLE caller has gone away | |
200 | * or the caller used UMH_NO_WAIT. | |
201 | */ | |
202 | if (comp) | |
203 | complete(comp); | |
204 | else | |
205 | call_usermodehelper_freeinfo(sub_info); | |
206 | } | |
207 | ||
1da177e4 LT |
208 | /* |
209 | * This is the task which runs the usermode application | |
210 | */ | |
b6b50a81 | 211 | static int call_usermodehelper_exec_async(void *data) |
1da177e4 LT |
212 | { |
213 | struct subprocess_info *sub_info = data; | |
17f60a7d | 214 | struct cred *new; |
1da177e4 LT |
215 | int retval; |
216 | ||
1da177e4 LT |
217 | spin_lock_irq(¤t->sighand->siglock); |
218 | flush_signal_handlers(current, 1); | |
1da177e4 LT |
219 | spin_unlock_irq(¤t->sighand->siglock); |
220 | ||
b73a7e76 | 221 | /* |
90f02303 | 222 | * Our parent (unbound workqueue) runs with elevated scheduling |
b639e86b | 223 | * priority. Avoid propagating that into the userspace child. |
b73a7e76 JE |
224 | */ |
225 | set_user_nice(current, 0); | |
226 | ||
17f60a7d EP |
227 | retval = -ENOMEM; |
228 | new = prepare_kernel_cred(current); | |
229 | if (!new) | |
0baf2a4d | 230 | goto out; |
17f60a7d EP |
231 | |
232 | spin_lock(&umh_sysctl_lock); | |
233 | new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset); | |
234 | new->cap_inheritable = cap_intersect(usermodehelper_inheritable, | |
235 | new->cap_inheritable); | |
236 | spin_unlock(&umh_sysctl_lock); | |
237 | ||
87966996 DH |
238 | if (sub_info->init) { |
239 | retval = sub_info->init(sub_info, new); | |
240 | if (retval) { | |
241 | abort_creds(new); | |
0baf2a4d | 242 | goto out; |
87966996 DH |
243 | } |
244 | } | |
245 | ||
17f60a7d EP |
246 | commit_creds(new); |
247 | ||
c4ad8f98 | 248 | retval = do_execve(getname_kernel(sub_info->path), |
ae903caa AV |
249 | (const char __user *const __user *)sub_info->argv, |
250 | (const char __user *const __user *)sub_info->envp); | |
0baf2a4d MS |
251 | out: |
252 | sub_info->retval = retval; | |
b6b50a81 FW |
253 | /* |
254 | * call_usermodehelper_exec_sync() will call umh_complete | |
255 | * if UHM_WAIT_PROC. | |
256 | */ | |
7117bc88 | 257 | if (!(sub_info->wait & UMH_WAIT_PROC)) |
0baf2a4d | 258 | umh_complete(sub_info); |
a74fb73c AV |
259 | if (!retval) |
260 | return 0; | |
fb45550d | 261 | do_exit(0); |
1da177e4 LT |
262 | } |
263 | ||
bb304a5c FW |
264 | /* Handles UMH_WAIT_PROC. */ |
265 | static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info) | |
1da177e4 | 266 | { |
1da177e4 | 267 | pid_t pid; |
1da177e4 | 268 | |
7d642242 | 269 | /* If SIGCLD is ignored sys_wait4 won't populate the status. */ |
76e0a6f4 | 270 | kernel_sigaction(SIGCHLD, SIG_DFL); |
b6b50a81 | 271 | pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD); |
1da177e4 LT |
272 | if (pid < 0) { |
273 | sub_info->retval = pid; | |
274 | } else { | |
7d642242 | 275 | int ret = -ECHILD; |
1da177e4 LT |
276 | /* |
277 | * Normally it is bogus to call wait4() from in-kernel because | |
278 | * wait4() wants to write the exit code to a userspace address. | |
b639e86b | 279 | * But call_usermodehelper_exec_sync() always runs as kernel |
bb304a5c FW |
280 | * thread (workqueue) and put_user() to a kernel address works |
281 | * OK for kernel threads, due to their having an mm_segment_t | |
282 | * which spans the entire address space. | |
1da177e4 LT |
283 | * |
284 | * Thus the __user pointer cast is valid here. | |
285 | */ | |
111dbe0c BS |
286 | sys_wait4(pid, (int __user *)&ret, 0, NULL); |
287 | ||
288 | /* | |
b6b50a81 FW |
289 | * If ret is 0, either call_usermodehelper_exec_async failed and |
290 | * the real error code is already in sub_info->retval or | |
111dbe0c BS |
291 | * sub_info->retval is 0 anyway, so don't mess with it then. |
292 | */ | |
293 | if (ret) | |
294 | sub_info->retval = ret; | |
1da177e4 LT |
295 | } |
296 | ||
bb304a5c FW |
297 | /* Restore default kernel sig handler */ |
298 | kernel_sigaction(SIGCHLD, SIG_IGN); | |
299 | ||
b3449922 | 300 | umh_complete(sub_info); |
1da177e4 LT |
301 | } |
302 | ||
b639e86b | 303 | /* |
bb304a5c | 304 | * We need to create the usermodehelper kernel thread from a task that is affine |
90f02303 FW |
305 | * to an optimized set of CPUs (or nohz housekeeping ones) such that they |
306 | * inherit a widest affinity irrespective of call_usermodehelper() callers with | |
307 | * possibly reduced affinity (eg: per-cpu workqueues). We don't want | |
308 | * usermodehelper targets to contend a busy CPU. | |
309 | * | |
bb304a5c FW |
310 | * Unbound workqueues provide such wide affinity and allow to block on |
311 | * UMH_WAIT_PROC requests without blocking pending request (up to some limit). | |
b639e86b | 312 | * |
90f02303 FW |
313 | * Besides, workqueues provide the privilege level that caller might not have |
314 | * to perform the usermodehelper request. | |
b639e86b FW |
315 | * |
316 | */ | |
b6b50a81 | 317 | static void call_usermodehelper_exec_work(struct work_struct *work) |
1da177e4 | 318 | { |
65f27f38 DH |
319 | struct subprocess_info *sub_info = |
320 | container_of(work, struct subprocess_info, work); | |
1da177e4 | 321 | |
bb304a5c FW |
322 | if (sub_info->wait & UMH_WAIT_PROC) { |
323 | call_usermodehelper_exec_sync(sub_info); | |
324 | } else { | |
325 | pid_t pid; | |
52116139 ON |
326 | /* |
327 | * Use CLONE_PARENT to reparent it to kthreadd; we do not | |
328 | * want to pollute current->children, and we need a parent | |
329 | * that always ignores SIGCHLD to ensure auto-reaping. | |
330 | */ | |
b6b50a81 | 331 | pid = kernel_thread(call_usermodehelper_exec_async, sub_info, |
52116139 | 332 | CLONE_PARENT | 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 | */ |
6d2c5d6c | 515 | struct subprocess_info *call_usermodehelper_setup(const 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); |
64e90a8a GKH |
527 | |
528 | #ifdef CONFIG_STATIC_USERMODEHELPER | |
529 | sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH; | |
530 | #else | |
0ab4dc92 | 531 | sub_info->path = path; |
64e90a8a | 532 | #endif |
0ab4dc92 JF |
533 | sub_info->argv = argv; |
534 | sub_info->envp = envp; | |
938e4b22 LDM |
535 | |
536 | sub_info->cleanup = cleanup; | |
537 | sub_info->init = init; | |
538 | sub_info->data = data; | |
0ab4dc92 JF |
539 | out: |
540 | return sub_info; | |
541 | } | |
938e4b22 | 542 | EXPORT_SYMBOL(call_usermodehelper_setup); |
0ab4dc92 | 543 | |
0ab4dc92 JF |
544 | /** |
545 | * call_usermodehelper_exec - start a usermode application | |
546 | * @sub_info: information about the subprocessa | |
1da177e4 | 547 | * @wait: wait for the application to finish and return status. |
66e5b7e1 LDM |
548 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back |
549 | * when the program couldn't be exec'ed. This makes it safe to call | |
a98f0dd3 | 550 | * from interrupt context. |
1da177e4 LT |
551 | * |
552 | * Runs a user-space application. The application is started | |
90f02303 FW |
553 | * asynchronously if wait is not set, and runs as a child of system workqueues. |
554 | * (ie. it runs with full root capabilities and optimized affinity). | |
1da177e4 | 555 | */ |
9d944ef3 | 556 | int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) |
1da177e4 | 557 | { |
60be6b9a | 558 | DECLARE_COMPLETION_ONSTACK(done); |
78468033 | 559 | int retval = 0; |
1da177e4 | 560 | |
4c1c7be9 TH |
561 | if (!sub_info->path) { |
562 | call_usermodehelper_freeinfo(sub_info); | |
563 | return -EINVAL; | |
564 | } | |
ccd4b65a | 565 | helper_lock(); |
90f02303 | 566 | if (usermodehelper_disabled) { |
0ab4dc92 JF |
567 | retval = -EBUSY; |
568 | goto out; | |
569 | } | |
64e90a8a GKH |
570 | |
571 | /* | |
572 | * If there is no binary for us to call, then just return and get out of | |
573 | * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and | |
574 | * disable all call_usermodehelper() calls. | |
575 | */ | |
576 | if (strlen(sub_info->path) == 0) | |
577 | goto out; | |
578 | ||
0baf2a4d MS |
579 | /* |
580 | * Set the completion pointer only if there is a waiter. | |
581 | * This makes it possible to use umh_complete to free | |
582 | * the data structure in case of UMH_NO_WAIT. | |
583 | */ | |
584 | sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done; | |
a98f0dd3 AK |
585 | sub_info->wait = wait; |
586 | ||
90f02303 | 587 | queue_work(system_unbound_wq, &sub_info->work); |
78468033 NC |
588 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ |
589 | goto unlock; | |
d0bd587a ON |
590 | |
591 | if (wait & UMH_KILLABLE) { | |
592 | retval = wait_for_completion_killable(&done); | |
593 | if (!retval) | |
594 | goto wait_done; | |
595 | ||
596 | /* umh_complete() will see NULL and free sub_info */ | |
597 | if (xchg(&sub_info->complete, NULL)) | |
598 | goto unlock; | |
599 | /* fallthrough, umh_complete() was already called */ | |
600 | } | |
601 | ||
1da177e4 | 602 | wait_for_completion(&done); |
d0bd587a | 603 | wait_done: |
a98f0dd3 | 604 | retval = sub_info->retval; |
78468033 | 605 | out: |
0ab4dc92 | 606 | call_usermodehelper_freeinfo(sub_info); |
78468033 | 607 | unlock: |
ccd4b65a | 608 | helper_unlock(); |
a98f0dd3 | 609 | return retval; |
1da177e4 | 610 | } |
938e4b22 | 611 | EXPORT_SYMBOL(call_usermodehelper_exec); |
785042f2 | 612 | |
66e5b7e1 LDM |
613 | /** |
614 | * call_usermodehelper() - prepare and start a usermode application | |
615 | * @path: path to usermode executable | |
616 | * @argv: arg vector for process | |
617 | * @envp: environment for process | |
618 | * @wait: wait for the application to finish and return status. | |
619 | * when UMH_NO_WAIT don't wait at all, but you get no useful error back | |
620 | * when the program couldn't be exec'ed. This makes it safe to call | |
621 | * from interrupt context. | |
622 | * | |
623 | * This function is the equivalent to use call_usermodehelper_setup() and | |
624 | * call_usermodehelper_exec(). | |
79c743dd | 625 | */ |
6d2c5d6c | 626 | int call_usermodehelper(const char *path, char **argv, char **envp, int wait) |
785042f2 BH |
627 | { |
628 | struct subprocess_info *info; | |
629 | gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL; | |
630 | ||
938e4b22 | 631 | info = call_usermodehelper_setup(path, argv, envp, gfp_mask, |
66e5b7e1 | 632 | NULL, NULL, NULL); |
785042f2 BH |
633 | if (info == NULL) |
634 | return -ENOMEM; | |
635 | ||
785042f2 BH |
636 | return call_usermodehelper_exec(info, wait); |
637 | } | |
66e5b7e1 | 638 | EXPORT_SYMBOL(call_usermodehelper); |
1da177e4 | 639 | |
17f60a7d EP |
640 | static int proc_cap_handler(struct ctl_table *table, int write, |
641 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
642 | { | |
643 | struct ctl_table t; | |
644 | unsigned long cap_array[_KERNEL_CAPABILITY_U32S]; | |
645 | kernel_cap_t new_cap; | |
646 | int err, i; | |
647 | ||
648 | if (write && (!capable(CAP_SETPCAP) || | |
649 | !capable(CAP_SYS_MODULE))) | |
650 | return -EPERM; | |
651 | ||
652 | /* | |
653 | * convert from the global kernel_cap_t to the ulong array to print to | |
654 | * userspace if this is a read. | |
655 | */ | |
656 | spin_lock(&umh_sysctl_lock); | |
657 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) { | |
658 | if (table->data == CAP_BSET) | |
659 | cap_array[i] = usermodehelper_bset.cap[i]; | |
660 | else if (table->data == CAP_PI) | |
661 | cap_array[i] = usermodehelper_inheritable.cap[i]; | |
662 | else | |
663 | BUG(); | |
664 | } | |
665 | spin_unlock(&umh_sysctl_lock); | |
666 | ||
667 | t = *table; | |
668 | t.data = &cap_array; | |
669 | ||
670 | /* | |
671 | * actually read or write and array of ulongs from userspace. Remember | |
672 | * these are least significant 32 bits first | |
673 | */ | |
674 | err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); | |
675 | if (err < 0) | |
676 | return err; | |
677 | ||
678 | /* | |
679 | * convert from the sysctl array of ulongs to the kernel_cap_t | |
680 | * internal representation | |
681 | */ | |
682 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) | |
683 | new_cap.cap[i] = cap_array[i]; | |
684 | ||
685 | /* | |
686 | * Drop everything not in the new_cap (but don't add things) | |
687 | */ | |
688 | spin_lock(&umh_sysctl_lock); | |
689 | if (write) { | |
690 | if (table->data == CAP_BSET) | |
691 | usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap); | |
692 | if (table->data == CAP_PI) | |
693 | usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap); | |
694 | } | |
695 | spin_unlock(&umh_sysctl_lock); | |
696 | ||
697 | return 0; | |
698 | } | |
699 | ||
700 | struct ctl_table usermodehelper_table[] = { | |
701 | { | |
702 | .procname = "bset", | |
703 | .data = CAP_BSET, | |
704 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
705 | .mode = 0600, | |
706 | .proc_handler = proc_cap_handler, | |
707 | }, | |
708 | { | |
709 | .procname = "inheritable", | |
710 | .data = CAP_PI, | |
711 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
712 | .mode = 0600, | |
713 | .proc_handler = proc_cap_handler, | |
714 | }, | |
715 | { } | |
716 | }; |