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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | kmod, the new module loader (replaces kerneld) | |
3 | Kirk Petersen | |
4 | ||
5 | Reorganized not to be a daemon by Adam Richter, with guidance | |
6 | from Greg Zornetzer. | |
7 | ||
8 | Modified to avoid chroot and file sharing problems. | |
9 | Mikael Pettersson | |
10 | ||
11 | Limit the concurrent number of kmod modprobes to catch loops from | |
12 | "modprobe needs a service that is in a module". | |
13 | Keith Owens <kaos@ocs.com.au> December 1999 | |
14 | ||
15 | Unblock all signals when we exec a usermode process. | |
16 | Shuu Yamaguchi <shuu@wondernetworkresources.com> December 2000 | |
17 | ||
18 | call_usermodehelper wait flag, and remove exec_usermodehelper. | |
19 | Rusty Russell <rusty@rustcorp.com.au> Jan 2003 | |
20 | */ | |
1da177e4 LT |
21 | #include <linux/module.h> |
22 | #include <linux/sched.h> | |
23 | #include <linux/syscalls.h> | |
24 | #include <linux/unistd.h> | |
25 | #include <linux/kmod.h> | |
1da177e4 | 26 | #include <linux/slab.h> |
1da177e4 | 27 | #include <linux/completion.h> |
17f60a7d | 28 | #include <linux/cred.h> |
1da177e4 | 29 | #include <linux/file.h> |
9f3acc31 | 30 | #include <linux/fdtable.h> |
1da177e4 LT |
31 | #include <linux/workqueue.h> |
32 | #include <linux/security.h> | |
33 | #include <linux/mount.h> | |
34 | #include <linux/kernel.h> | |
35 | #include <linux/init.h> | |
d025c9db | 36 | #include <linux/resource.h> |
8cdd4936 RW |
37 | #include <linux/notifier.h> |
38 | #include <linux/suspend.h> | |
b298d289 | 39 | #include <linux/rwsem.h> |
1da177e4 LT |
40 | #include <asm/uaccess.h> |
41 | ||
7ead8b83 LZ |
42 | #include <trace/events/module.h> |
43 | ||
1da177e4 LT |
44 | extern int max_threads; |
45 | ||
46 | static struct workqueue_struct *khelper_wq; | |
47 | ||
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 | ||
63 | /** | |
acae0515 AV |
64 | * __request_module - try to load a kernel module |
65 | * @wait: wait (or not) for the operation to complete | |
bd4207c9 RD |
66 | * @fmt: printf style format string for the name of the module |
67 | * @...: arguments as specified in the format string | |
1da177e4 LT |
68 | * |
69 | * Load a module using the user mode module loader. The function returns | |
70 | * zero on success or a negative errno code on failure. Note that a | |
71 | * successful module load does not mean the module did not then unload | |
72 | * and exit on an error of its own. Callers must check that the service | |
73 | * they requested is now available not blindly invoke it. | |
74 | * | |
75 | * If module auto-loading support is disabled then this function | |
76 | * becomes a no-operation. | |
77 | */ | |
acae0515 | 78 | int __request_module(bool wait, const char *fmt, ...) |
1da177e4 LT |
79 | { |
80 | va_list args; | |
81 | char module_name[MODULE_NAME_LEN]; | |
82 | unsigned int max_modprobes; | |
83 | int ret; | |
84 | char *argv[] = { modprobe_path, "-q", "--", module_name, NULL }; | |
85 | static char *envp[] = { "HOME=/", | |
86 | "TERM=linux", | |
87 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
88 | NULL }; | |
89 | static atomic_t kmod_concurrent = ATOMIC_INIT(0); | |
90 | #define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */ | |
91 | static int kmod_loop_msg; | |
92 | ||
93 | va_start(args, fmt); | |
94 | ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args); | |
95 | va_end(args); | |
96 | if (ret >= MODULE_NAME_LEN) | |
97 | return -ENAMETOOLONG; | |
98 | ||
dd8dbf2e EP |
99 | ret = security_kernel_module_request(module_name); |
100 | if (ret) | |
101 | return ret; | |
102 | ||
1da177e4 LT |
103 | /* If modprobe needs a service that is in a module, we get a recursive |
104 | * loop. Limit the number of running kmod threads to max_threads/2 or | |
105 | * MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method | |
106 | * would be to run the parents of this process, counting how many times | |
107 | * kmod was invoked. That would mean accessing the internals of the | |
108 | * process tables to get the command line, proc_pid_cmdline is static | |
109 | * and it is not worth changing the proc code just to handle this case. | |
110 | * KAO. | |
111 | * | |
112 | * "trace the ppid" is simple, but will fail if someone's | |
113 | * parent exits. I think this is as good as it gets. --RR | |
114 | */ | |
115 | max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT); | |
116 | atomic_inc(&kmod_concurrent); | |
117 | if (atomic_read(&kmod_concurrent) > max_modprobes) { | |
118 | /* We may be blaming an innocent here, but unlikely */ | |
37252db6 | 119 | if (kmod_loop_msg < 5) { |
1da177e4 LT |
120 | printk(KERN_ERR |
121 | "request_module: runaway loop modprobe %s\n", | |
122 | module_name); | |
37252db6 JK |
123 | kmod_loop_msg++; |
124 | } | |
1da177e4 LT |
125 | atomic_dec(&kmod_concurrent); |
126 | return -ENOMEM; | |
127 | } | |
128 | ||
7ead8b83 LZ |
129 | trace_module_request(module_name, wait, _RET_IP_); |
130 | ||
a06a4dc3 NH |
131 | ret = call_usermodehelper_fns(modprobe_path, argv, envp, |
132 | wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC, | |
133 | NULL, NULL, NULL); | |
134 | ||
1da177e4 LT |
135 | atomic_dec(&kmod_concurrent); |
136 | return ret; | |
137 | } | |
acae0515 | 138 | EXPORT_SYMBOL(__request_module); |
118a9069 | 139 | #endif /* CONFIG_MODULES */ |
1da177e4 | 140 | |
1da177e4 LT |
141 | /* |
142 | * This is the task which runs the usermode application | |
143 | */ | |
144 | static int ____call_usermodehelper(void *data) | |
145 | { | |
146 | struct subprocess_info *sub_info = data; | |
17f60a7d | 147 | struct cred *new; |
1da177e4 LT |
148 | int retval; |
149 | ||
1da177e4 LT |
150 | spin_lock_irq(¤t->sighand->siglock); |
151 | flush_signal_handlers(current, 1); | |
1da177e4 LT |
152 | spin_unlock_irq(¤t->sighand->siglock); |
153 | ||
154 | /* We can run anywhere, unlike our parent keventd(). */ | |
1a2142af | 155 | set_cpus_allowed_ptr(current, cpu_all_mask); |
1da177e4 | 156 | |
b73a7e76 JE |
157 | /* |
158 | * Our parent is keventd, which runs with elevated scheduling priority. | |
159 | * Avoid propagating that into the userspace child. | |
160 | */ | |
161 | set_user_nice(current, 0); | |
162 | ||
17f60a7d EP |
163 | retval = -ENOMEM; |
164 | new = prepare_kernel_cred(current); | |
165 | if (!new) | |
166 | goto fail; | |
167 | ||
168 | spin_lock(&umh_sysctl_lock); | |
169 | new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset); | |
170 | new->cap_inheritable = cap_intersect(usermodehelper_inheritable, | |
171 | new->cap_inheritable); | |
172 | spin_unlock(&umh_sysctl_lock); | |
173 | ||
87966996 DH |
174 | if (sub_info->init) { |
175 | retval = sub_info->init(sub_info, new); | |
176 | if (retval) { | |
177 | abort_creds(new); | |
178 | goto fail; | |
179 | } | |
180 | } | |
181 | ||
17f60a7d EP |
182 | commit_creds(new); |
183 | ||
d7627467 DH |
184 | retval = kernel_execve(sub_info->path, |
185 | (const char *const *)sub_info->argv, | |
186 | (const char *const *)sub_info->envp); | |
1da177e4 LT |
187 | |
188 | /* Exec failed? */ | |
a06a4dc3 | 189 | fail: |
1da177e4 LT |
190 | sub_info->retval = retval; |
191 | do_exit(0); | |
192 | } | |
193 | ||
0ab4dc92 JF |
194 | void call_usermodehelper_freeinfo(struct subprocess_info *info) |
195 | { | |
196 | if (info->cleanup) | |
a06a4dc3 | 197 | (*info->cleanup)(info); |
0ab4dc92 JF |
198 | kfree(info); |
199 | } | |
200 | EXPORT_SYMBOL(call_usermodehelper_freeinfo); | |
201 | ||
b3449922 ON |
202 | static void umh_complete(struct subprocess_info *sub_info) |
203 | { | |
d0bd587a ON |
204 | struct completion *comp = xchg(&sub_info->complete, NULL); |
205 | /* | |
206 | * See call_usermodehelper_exec(). If xchg() returns NULL | |
207 | * we own sub_info, the UMH_KILLABLE caller has gone away. | |
208 | */ | |
209 | if (comp) | |
210 | complete(comp); | |
211 | else | |
212 | call_usermodehelper_freeinfo(sub_info); | |
b3449922 ON |
213 | } |
214 | ||
1da177e4 LT |
215 | /* Keventd can't block, but this (a child) can. */ |
216 | static int wait_for_helper(void *data) | |
217 | { | |
218 | struct subprocess_info *sub_info = data; | |
219 | pid_t pid; | |
1da177e4 | 220 | |
7d642242 ON |
221 | /* If SIGCLD is ignored sys_wait4 won't populate the status. */ |
222 | spin_lock_irq(¤t->sighand->siglock); | |
223 | current->sighand->action[SIGCHLD-1].sa.sa_handler = SIG_DFL; | |
224 | spin_unlock_irq(¤t->sighand->siglock); | |
1da177e4 LT |
225 | |
226 | pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD); | |
227 | if (pid < 0) { | |
228 | sub_info->retval = pid; | |
229 | } else { | |
7d642242 | 230 | int ret = -ECHILD; |
1da177e4 LT |
231 | /* |
232 | * Normally it is bogus to call wait4() from in-kernel because | |
233 | * wait4() wants to write the exit code to a userspace address. | |
234 | * But wait_for_helper() always runs as keventd, and put_user() | |
235 | * to a kernel address works OK for kernel threads, due to their | |
236 | * having an mm_segment_t which spans the entire address space. | |
237 | * | |
238 | * Thus the __user pointer cast is valid here. | |
239 | */ | |
111dbe0c BS |
240 | sys_wait4(pid, (int __user *)&ret, 0, NULL); |
241 | ||
242 | /* | |
243 | * If ret is 0, either ____call_usermodehelper failed and the | |
244 | * real error code is already in sub_info->retval or | |
245 | * sub_info->retval is 0 anyway, so don't mess with it then. | |
246 | */ | |
247 | if (ret) | |
248 | sub_info->retval = ret; | |
1da177e4 LT |
249 | } |
250 | ||
b3449922 | 251 | umh_complete(sub_info); |
1da177e4 LT |
252 | return 0; |
253 | } | |
254 | ||
255 | /* This is run by khelper thread */ | |
65f27f38 | 256 | static void __call_usermodehelper(struct work_struct *work) |
1da177e4 | 257 | { |
65f27f38 DH |
258 | struct subprocess_info *sub_info = |
259 | container_of(work, struct subprocess_info, work); | |
86313c48 | 260 | enum umh_wait wait = sub_info->wait; |
d47419cd | 261 | pid_t pid; |
1da177e4 | 262 | |
d0bd587a ON |
263 | if (wait != UMH_NO_WAIT) |
264 | wait &= ~UMH_KILLABLE; | |
265 | ||
1da177e4 LT |
266 | /* CLONE_VFORK: wait until the usermode helper has execve'd |
267 | * successfully We need the data structures to stay around | |
268 | * until that is done. */ | |
d47419cd | 269 | if (wait == UMH_WAIT_PROC) |
1da177e4 LT |
270 | pid = kernel_thread(wait_for_helper, sub_info, |
271 | CLONE_FS | CLONE_FILES | SIGCHLD); | |
272 | else | |
273 | pid = kernel_thread(____call_usermodehelper, sub_info, | |
274 | CLONE_VFORK | SIGCHLD); | |
275 | ||
86313c48 JF |
276 | switch (wait) { |
277 | case UMH_NO_WAIT: | |
d47419cd | 278 | call_usermodehelper_freeinfo(sub_info); |
86313c48 | 279 | break; |
a98f0dd3 | 280 | |
86313c48 JF |
281 | case UMH_WAIT_PROC: |
282 | if (pid > 0) | |
283 | break; | |
86313c48 | 284 | /* FALLTHROUGH */ |
86313c48 | 285 | case UMH_WAIT_EXEC: |
04b1c384 ON |
286 | if (pid < 0) |
287 | sub_info->retval = pid; | |
b3449922 | 288 | umh_complete(sub_info); |
86313c48 | 289 | } |
1da177e4 LT |
290 | } |
291 | ||
ccd4b65a RW |
292 | /* |
293 | * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY | |
294 | * (used for preventing user land processes from being created after the user | |
295 | * land has been frozen during a system-wide hibernation or suspend operation). | |
b298d289 | 296 | * Should always be manipulated under umhelper_sem acquired for write. |
ccd4b65a | 297 | */ |
288d5abe | 298 | static int usermodehelper_disabled = 1; |
ccd4b65a RW |
299 | |
300 | /* Number of helpers running */ | |
301 | static atomic_t running_helpers = ATOMIC_INIT(0); | |
302 | ||
303 | /* | |
5307427a | 304 | * Wait queue head used by usermodehelper_disable() to wait for all running |
ccd4b65a RW |
305 | * helpers to finish. |
306 | */ | |
307 | static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); | |
308 | ||
309 | /* | |
310 | * Time to wait for running_helpers to become zero before the setting of | |
5307427a | 311 | * usermodehelper_disabled in usermodehelper_disable() fails |
ccd4b65a RW |
312 | */ |
313 | #define RUNNING_HELPERS_TIMEOUT (5 * HZ) | |
314 | ||
b298d289 SB |
315 | void read_lock_usermodehelper(void) |
316 | { | |
317 | down_read(&umhelper_sem); | |
318 | } | |
319 | EXPORT_SYMBOL_GPL(read_lock_usermodehelper); | |
320 | ||
321 | void read_unlock_usermodehelper(void) | |
322 | { | |
323 | up_read(&umhelper_sem); | |
324 | } | |
325 | EXPORT_SYMBOL_GPL(read_unlock_usermodehelper); | |
326 | ||
1bfcf130 RW |
327 | /** |
328 | * usermodehelper_disable - prevent new helpers from being started | |
329 | */ | |
330 | int usermodehelper_disable(void) | |
8cdd4936 | 331 | { |
ccd4b65a RW |
332 | long retval; |
333 | ||
b298d289 | 334 | down_write(&umhelper_sem); |
1bfcf130 | 335 | usermodehelper_disabled = 1; |
b298d289 SB |
336 | up_write(&umhelper_sem); |
337 | ||
1bfcf130 RW |
338 | /* |
339 | * From now on call_usermodehelper_exec() won't start any new | |
340 | * helpers, so it is sufficient if running_helpers turns out to | |
341 | * be zero at one point (it may be increased later, but that | |
342 | * doesn't matter). | |
343 | */ | |
344 | retval = wait_event_timeout(running_helpers_waitq, | |
ccd4b65a RW |
345 | atomic_read(&running_helpers) == 0, |
346 | RUNNING_HELPERS_TIMEOUT); | |
1bfcf130 RW |
347 | if (retval) |
348 | return 0; | |
8cdd4936 | 349 | |
b298d289 | 350 | down_write(&umhelper_sem); |
1bfcf130 | 351 | usermodehelper_disabled = 0; |
b298d289 | 352 | up_write(&umhelper_sem); |
1bfcf130 RW |
353 | return -EAGAIN; |
354 | } | |
355 | ||
356 | /** | |
357 | * usermodehelper_enable - allow new helpers to be started again | |
358 | */ | |
359 | void usermodehelper_enable(void) | |
360 | { | |
b298d289 | 361 | down_write(&umhelper_sem); |
1bfcf130 | 362 | usermodehelper_disabled = 0; |
b298d289 | 363 | up_write(&umhelper_sem); |
8cdd4936 RW |
364 | } |
365 | ||
a144c6a6 RW |
366 | /** |
367 | * usermodehelper_is_disabled - check if new helpers are allowed to be started | |
368 | */ | |
369 | bool usermodehelper_is_disabled(void) | |
370 | { | |
371 | return usermodehelper_disabled; | |
372 | } | |
373 | EXPORT_SYMBOL_GPL(usermodehelper_is_disabled); | |
374 | ||
ccd4b65a RW |
375 | static void helper_lock(void) |
376 | { | |
377 | atomic_inc(&running_helpers); | |
378 | smp_mb__after_atomic_inc(); | |
379 | } | |
380 | ||
381 | static void helper_unlock(void) | |
382 | { | |
383 | if (atomic_dec_and_test(&running_helpers)) | |
384 | wake_up(&running_helpers_waitq); | |
385 | } | |
ccd4b65a | 386 | |
1da177e4 | 387 | /** |
0ab4dc92 | 388 | * call_usermodehelper_setup - prepare to call a usermode helper |
61df47c8 RD |
389 | * @path: path to usermode executable |
390 | * @argv: arg vector for process | |
391 | * @envp: environment for process | |
ac331d15 | 392 | * @gfp_mask: gfp mask for memory allocation |
0ab4dc92 | 393 | * |
61df47c8 | 394 | * Returns either %NULL on allocation failure, or a subprocess_info |
0ab4dc92 JF |
395 | * structure. This should be passed to call_usermodehelper_exec to |
396 | * exec the process and free the structure. | |
397 | */ | |
ac331d15 KM |
398 | struct subprocess_info *call_usermodehelper_setup(char *path, char **argv, |
399 | char **envp, gfp_t gfp_mask) | |
0ab4dc92 JF |
400 | { |
401 | struct subprocess_info *sub_info; | |
ac331d15 | 402 | sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask); |
0ab4dc92 JF |
403 | if (!sub_info) |
404 | goto out; | |
405 | ||
406 | INIT_WORK(&sub_info->work, __call_usermodehelper); | |
407 | sub_info->path = path; | |
408 | sub_info->argv = argv; | |
409 | sub_info->envp = envp; | |
0ab4dc92 JF |
410 | out: |
411 | return sub_info; | |
412 | } | |
413 | EXPORT_SYMBOL(call_usermodehelper_setup); | |
414 | ||
0ab4dc92 | 415 | /** |
a06a4dc3 | 416 | * call_usermodehelper_setfns - set a cleanup/init function |
0ab4dc92 JF |
417 | * @info: a subprocess_info returned by call_usermodehelper_setup |
418 | * @cleanup: a cleanup function | |
a06a4dc3 NH |
419 | * @init: an init function |
420 | * @data: arbitrary context sensitive data | |
421 | * | |
422 | * The init function is used to customize the helper process prior to | |
423 | * exec. A non-zero return code causes the process to error out, exit, | |
424 | * and return the failure to the calling process | |
0ab4dc92 | 425 | * |
a06a4dc3 | 426 | * The cleanup function is just before ethe subprocess_info is about to |
0ab4dc92 JF |
427 | * be freed. This can be used for freeing the argv and envp. The |
428 | * Function must be runnable in either a process context or the | |
429 | * context in which call_usermodehelper_exec is called. | |
430 | */ | |
a06a4dc3 | 431 | void call_usermodehelper_setfns(struct subprocess_info *info, |
87966996 | 432 | int (*init)(struct subprocess_info *info, struct cred *new), |
a06a4dc3 NH |
433 | void (*cleanup)(struct subprocess_info *info), |
434 | void *data) | |
0ab4dc92 JF |
435 | { |
436 | info->cleanup = cleanup; | |
a06a4dc3 NH |
437 | info->init = init; |
438 | info->data = data; | |
0ab4dc92 | 439 | } |
a06a4dc3 | 440 | EXPORT_SYMBOL(call_usermodehelper_setfns); |
0ab4dc92 | 441 | |
0ab4dc92 JF |
442 | /** |
443 | * call_usermodehelper_exec - start a usermode application | |
444 | * @sub_info: information about the subprocessa | |
1da177e4 | 445 | * @wait: wait for the application to finish and return status. |
a98f0dd3 AK |
446 | * when -1 don't wait at all, but you get no useful error back when |
447 | * the program couldn't be exec'ed. This makes it safe to call | |
448 | * from interrupt context. | |
1da177e4 LT |
449 | * |
450 | * Runs a user-space application. The application is started | |
451 | * asynchronously if wait is not set, and runs as a child of keventd. | |
452 | * (ie. it runs with full root capabilities). | |
1da177e4 | 453 | */ |
0ab4dc92 | 454 | int call_usermodehelper_exec(struct subprocess_info *sub_info, |
86313c48 | 455 | enum umh_wait wait) |
1da177e4 | 456 | { |
60be6b9a | 457 | DECLARE_COMPLETION_ONSTACK(done); |
78468033 | 458 | int retval = 0; |
1da177e4 | 459 | |
ccd4b65a | 460 | helper_lock(); |
78468033 | 461 | if (sub_info->path[0] == '\0') |
0ab4dc92 | 462 | goto out; |
1da177e4 | 463 | |
8cdd4936 | 464 | if (!khelper_wq || usermodehelper_disabled) { |
0ab4dc92 JF |
465 | retval = -EBUSY; |
466 | goto out; | |
467 | } | |
a98f0dd3 | 468 | |
a98f0dd3 | 469 | sub_info->complete = &done; |
a98f0dd3 AK |
470 | sub_info->wait = wait; |
471 | ||
472 | queue_work(khelper_wq, &sub_info->work); | |
78468033 NC |
473 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ |
474 | goto unlock; | |
d0bd587a ON |
475 | |
476 | if (wait & UMH_KILLABLE) { | |
477 | retval = wait_for_completion_killable(&done); | |
478 | if (!retval) | |
479 | goto wait_done; | |
480 | ||
481 | /* umh_complete() will see NULL and free sub_info */ | |
482 | if (xchg(&sub_info->complete, NULL)) | |
483 | goto unlock; | |
484 | /* fallthrough, umh_complete() was already called */ | |
485 | } | |
486 | ||
1da177e4 | 487 | wait_for_completion(&done); |
d0bd587a | 488 | wait_done: |
a98f0dd3 | 489 | retval = sub_info->retval; |
78468033 | 490 | out: |
0ab4dc92 | 491 | call_usermodehelper_freeinfo(sub_info); |
78468033 | 492 | unlock: |
ccd4b65a | 493 | helper_unlock(); |
a98f0dd3 | 494 | return retval; |
1da177e4 | 495 | } |
0ab4dc92 | 496 | EXPORT_SYMBOL(call_usermodehelper_exec); |
1da177e4 | 497 | |
17f60a7d EP |
498 | static int proc_cap_handler(struct ctl_table *table, int write, |
499 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
500 | { | |
501 | struct ctl_table t; | |
502 | unsigned long cap_array[_KERNEL_CAPABILITY_U32S]; | |
503 | kernel_cap_t new_cap; | |
504 | int err, i; | |
505 | ||
506 | if (write && (!capable(CAP_SETPCAP) || | |
507 | !capable(CAP_SYS_MODULE))) | |
508 | return -EPERM; | |
509 | ||
510 | /* | |
511 | * convert from the global kernel_cap_t to the ulong array to print to | |
512 | * userspace if this is a read. | |
513 | */ | |
514 | spin_lock(&umh_sysctl_lock); | |
515 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) { | |
516 | if (table->data == CAP_BSET) | |
517 | cap_array[i] = usermodehelper_bset.cap[i]; | |
518 | else if (table->data == CAP_PI) | |
519 | cap_array[i] = usermodehelper_inheritable.cap[i]; | |
520 | else | |
521 | BUG(); | |
522 | } | |
523 | spin_unlock(&umh_sysctl_lock); | |
524 | ||
525 | t = *table; | |
526 | t.data = &cap_array; | |
527 | ||
528 | /* | |
529 | * actually read or write and array of ulongs from userspace. Remember | |
530 | * these are least significant 32 bits first | |
531 | */ | |
532 | err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); | |
533 | if (err < 0) | |
534 | return err; | |
535 | ||
536 | /* | |
537 | * convert from the sysctl array of ulongs to the kernel_cap_t | |
538 | * internal representation | |
539 | */ | |
540 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) | |
541 | new_cap.cap[i] = cap_array[i]; | |
542 | ||
543 | /* | |
544 | * Drop everything not in the new_cap (but don't add things) | |
545 | */ | |
546 | spin_lock(&umh_sysctl_lock); | |
547 | if (write) { | |
548 | if (table->data == CAP_BSET) | |
549 | usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap); | |
550 | if (table->data == CAP_PI) | |
551 | usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap); | |
552 | } | |
553 | spin_unlock(&umh_sysctl_lock); | |
554 | ||
555 | return 0; | |
556 | } | |
557 | ||
558 | struct ctl_table usermodehelper_table[] = { | |
559 | { | |
560 | .procname = "bset", | |
561 | .data = CAP_BSET, | |
562 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
563 | .mode = 0600, | |
564 | .proc_handler = proc_cap_handler, | |
565 | }, | |
566 | { | |
567 | .procname = "inheritable", | |
568 | .data = CAP_PI, | |
569 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
570 | .mode = 0600, | |
571 | .proc_handler = proc_cap_handler, | |
572 | }, | |
573 | { } | |
574 | }; | |
575 | ||
1da177e4 LT |
576 | void __init usermodehelper_init(void) |
577 | { | |
578 | khelper_wq = create_singlethread_workqueue("khelper"); | |
579 | BUG_ON(!khelper_wq); | |
580 | } |