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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> |
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 | ||
3e63a93b ON |
63 | static int call_modprobe(char *module_name, int wait) |
64 | { | |
65 | static char *envp[] = { | |
66 | "HOME=/", | |
67 | "TERM=linux", | |
68 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
69 | NULL | |
70 | }; | |
71 | ||
72 | char *argv[] = { modprobe_path, "-q", "--", module_name, NULL }; | |
73 | ||
74 | return call_usermodehelper_fns(modprobe_path, argv, envp, | |
75 | wait, NULL, NULL, NULL); | |
76 | } | |
77 | ||
1da177e4 | 78 | /** |
acae0515 AV |
79 | * __request_module - try to load a kernel module |
80 | * @wait: wait (or not) for the operation to complete | |
bd4207c9 RD |
81 | * @fmt: printf style format string for the name of the module |
82 | * @...: arguments as specified in the format string | |
1da177e4 LT |
83 | * |
84 | * Load a module using the user mode module loader. The function returns | |
85 | * zero on success or a negative errno code on failure. Note that a | |
86 | * successful module load does not mean the module did not then unload | |
87 | * and exit on an error of its own. Callers must check that the service | |
88 | * they requested is now available not blindly invoke it. | |
89 | * | |
90 | * If module auto-loading support is disabled then this function | |
91 | * becomes a no-operation. | |
92 | */ | |
acae0515 | 93 | int __request_module(bool wait, const char *fmt, ...) |
1da177e4 LT |
94 | { |
95 | va_list args; | |
96 | char module_name[MODULE_NAME_LEN]; | |
97 | unsigned int max_modprobes; | |
98 | int ret; | |
1da177e4 LT |
99 | static atomic_t kmod_concurrent = ATOMIC_INIT(0); |
100 | #define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */ | |
101 | static int kmod_loop_msg; | |
102 | ||
103 | va_start(args, fmt); | |
104 | ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args); | |
105 | va_end(args); | |
106 | if (ret >= MODULE_NAME_LEN) | |
107 | return -ENAMETOOLONG; | |
108 | ||
dd8dbf2e EP |
109 | ret = security_kernel_module_request(module_name); |
110 | if (ret) | |
111 | return ret; | |
112 | ||
1da177e4 LT |
113 | /* If modprobe needs a service that is in a module, we get a recursive |
114 | * loop. Limit the number of running kmod threads to max_threads/2 or | |
115 | * MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method | |
116 | * would be to run the parents of this process, counting how many times | |
117 | * kmod was invoked. That would mean accessing the internals of the | |
118 | * process tables to get the command line, proc_pid_cmdline is static | |
119 | * and it is not worth changing the proc code just to handle this case. | |
120 | * KAO. | |
121 | * | |
122 | * "trace the ppid" is simple, but will fail if someone's | |
123 | * parent exits. I think this is as good as it gets. --RR | |
124 | */ | |
125 | max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT); | |
126 | atomic_inc(&kmod_concurrent); | |
127 | if (atomic_read(&kmod_concurrent) > max_modprobes) { | |
128 | /* We may be blaming an innocent here, but unlikely */ | |
37252db6 | 129 | if (kmod_loop_msg < 5) { |
1da177e4 LT |
130 | printk(KERN_ERR |
131 | "request_module: runaway loop modprobe %s\n", | |
132 | module_name); | |
37252db6 JK |
133 | kmod_loop_msg++; |
134 | } | |
1da177e4 LT |
135 | atomic_dec(&kmod_concurrent); |
136 | return -ENOMEM; | |
137 | } | |
138 | ||
7ead8b83 LZ |
139 | trace_module_request(module_name, wait, _RET_IP_); |
140 | ||
3e63a93b | 141 | ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC); |
a06a4dc3 | 142 | |
1da177e4 LT |
143 | atomic_dec(&kmod_concurrent); |
144 | return ret; | |
145 | } | |
acae0515 | 146 | EXPORT_SYMBOL(__request_module); |
118a9069 | 147 | #endif /* CONFIG_MODULES */ |
1da177e4 | 148 | |
1da177e4 LT |
149 | /* |
150 | * This is the task which runs the usermode application | |
151 | */ | |
152 | static int ____call_usermodehelper(void *data) | |
153 | { | |
154 | struct subprocess_info *sub_info = data; | |
17f60a7d | 155 | struct cred *new; |
1da177e4 LT |
156 | int retval; |
157 | ||
1da177e4 LT |
158 | spin_lock_irq(¤t->sighand->siglock); |
159 | flush_signal_handlers(current, 1); | |
1da177e4 LT |
160 | spin_unlock_irq(¤t->sighand->siglock); |
161 | ||
162 | /* We can run anywhere, unlike our parent keventd(). */ | |
1a2142af | 163 | set_cpus_allowed_ptr(current, cpu_all_mask); |
1da177e4 | 164 | |
b73a7e76 JE |
165 | /* |
166 | * Our parent is keventd, which runs with elevated scheduling priority. | |
167 | * Avoid propagating that into the userspace child. | |
168 | */ | |
169 | set_user_nice(current, 0); | |
170 | ||
17f60a7d EP |
171 | retval = -ENOMEM; |
172 | new = prepare_kernel_cred(current); | |
173 | if (!new) | |
174 | goto fail; | |
175 | ||
176 | spin_lock(&umh_sysctl_lock); | |
177 | new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset); | |
178 | new->cap_inheritable = cap_intersect(usermodehelper_inheritable, | |
179 | new->cap_inheritable); | |
180 | spin_unlock(&umh_sysctl_lock); | |
181 | ||
87966996 DH |
182 | if (sub_info->init) { |
183 | retval = sub_info->init(sub_info, new); | |
184 | if (retval) { | |
185 | abort_creds(new); | |
186 | goto fail; | |
187 | } | |
188 | } | |
189 | ||
17f60a7d EP |
190 | commit_creds(new); |
191 | ||
d7627467 DH |
192 | retval = kernel_execve(sub_info->path, |
193 | (const char *const *)sub_info->argv, | |
194 | (const char *const *)sub_info->envp); | |
1da177e4 LT |
195 | |
196 | /* Exec failed? */ | |
a06a4dc3 | 197 | fail: |
1da177e4 | 198 | sub_info->retval = retval; |
5b9bd473 | 199 | return 0; |
1da177e4 LT |
200 | } |
201 | ||
0ab4dc92 JF |
202 | void call_usermodehelper_freeinfo(struct subprocess_info *info) |
203 | { | |
204 | if (info->cleanup) | |
a06a4dc3 | 205 | (*info->cleanup)(info); |
0ab4dc92 JF |
206 | kfree(info); |
207 | } | |
208 | EXPORT_SYMBOL(call_usermodehelper_freeinfo); | |
209 | ||
b3449922 ON |
210 | static void umh_complete(struct subprocess_info *sub_info) |
211 | { | |
d0bd587a ON |
212 | struct completion *comp = xchg(&sub_info->complete, NULL); |
213 | /* | |
214 | * See call_usermodehelper_exec(). If xchg() returns NULL | |
215 | * we own sub_info, the UMH_KILLABLE caller has gone away. | |
216 | */ | |
217 | if (comp) | |
218 | complete(comp); | |
219 | else | |
220 | call_usermodehelper_freeinfo(sub_info); | |
b3449922 ON |
221 | } |
222 | ||
1da177e4 LT |
223 | /* Keventd can't block, but this (a child) can. */ |
224 | static int wait_for_helper(void *data) | |
225 | { | |
226 | struct subprocess_info *sub_info = data; | |
227 | pid_t pid; | |
1da177e4 | 228 | |
7d642242 ON |
229 | /* If SIGCLD is ignored sys_wait4 won't populate the status. */ |
230 | spin_lock_irq(¤t->sighand->siglock); | |
231 | current->sighand->action[SIGCHLD-1].sa.sa_handler = SIG_DFL; | |
232 | spin_unlock_irq(¤t->sighand->siglock); | |
1da177e4 LT |
233 | |
234 | pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD); | |
235 | if (pid < 0) { | |
236 | sub_info->retval = pid; | |
237 | } else { | |
7d642242 | 238 | int ret = -ECHILD; |
1da177e4 LT |
239 | /* |
240 | * Normally it is bogus to call wait4() from in-kernel because | |
241 | * wait4() wants to write the exit code to a userspace address. | |
242 | * But wait_for_helper() always runs as keventd, and put_user() | |
243 | * to a kernel address works OK for kernel threads, due to their | |
244 | * having an mm_segment_t which spans the entire address space. | |
245 | * | |
246 | * Thus the __user pointer cast is valid here. | |
247 | */ | |
111dbe0c BS |
248 | sys_wait4(pid, (int __user *)&ret, 0, NULL); |
249 | ||
250 | /* | |
251 | * If ret is 0, either ____call_usermodehelper failed and the | |
252 | * real error code is already in sub_info->retval or | |
253 | * sub_info->retval is 0 anyway, so don't mess with it then. | |
254 | */ | |
255 | if (ret) | |
256 | sub_info->retval = ret; | |
1da177e4 LT |
257 | } |
258 | ||
b3449922 | 259 | umh_complete(sub_info); |
1da177e4 LT |
260 | return 0; |
261 | } | |
262 | ||
263 | /* This is run by khelper thread */ | |
65f27f38 | 264 | static void __call_usermodehelper(struct work_struct *work) |
1da177e4 | 265 | { |
65f27f38 DH |
266 | struct subprocess_info *sub_info = |
267 | container_of(work, struct subprocess_info, work); | |
9d944ef3 | 268 | int wait = sub_info->wait & ~UMH_KILLABLE; |
d47419cd | 269 | pid_t pid; |
1da177e4 LT |
270 | |
271 | /* CLONE_VFORK: wait until the usermode helper has execve'd | |
272 | * successfully We need the data structures to stay around | |
273 | * until that is done. */ | |
d47419cd | 274 | if (wait == UMH_WAIT_PROC) |
1da177e4 LT |
275 | pid = kernel_thread(wait_for_helper, sub_info, |
276 | CLONE_FS | CLONE_FILES | SIGCHLD); | |
277 | else | |
278 | pid = kernel_thread(____call_usermodehelper, sub_info, | |
279 | CLONE_VFORK | SIGCHLD); | |
280 | ||
86313c48 JF |
281 | switch (wait) { |
282 | case UMH_NO_WAIT: | |
d47419cd | 283 | call_usermodehelper_freeinfo(sub_info); |
86313c48 | 284 | break; |
a98f0dd3 | 285 | |
86313c48 JF |
286 | case UMH_WAIT_PROC: |
287 | if (pid > 0) | |
288 | break; | |
86313c48 | 289 | /* FALLTHROUGH */ |
86313c48 | 290 | case UMH_WAIT_EXEC: |
04b1c384 ON |
291 | if (pid < 0) |
292 | sub_info->retval = pid; | |
b3449922 | 293 | umh_complete(sub_info); |
86313c48 | 294 | } |
1da177e4 LT |
295 | } |
296 | ||
ccd4b65a RW |
297 | /* |
298 | * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY | |
299 | * (used for preventing user land processes from being created after the user | |
300 | * land has been frozen during a system-wide hibernation or suspend operation). | |
b298d289 | 301 | * Should always be manipulated under umhelper_sem acquired for write. |
ccd4b65a | 302 | */ |
288d5abe | 303 | static int usermodehelper_disabled = 1; |
ccd4b65a RW |
304 | |
305 | /* Number of helpers running */ | |
306 | static atomic_t running_helpers = ATOMIC_INIT(0); | |
307 | ||
308 | /* | |
5307427a | 309 | * Wait queue head used by usermodehelper_disable() to wait for all running |
ccd4b65a RW |
310 | * helpers to finish. |
311 | */ | |
312 | static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); | |
313 | ||
314 | /* | |
315 | * Time to wait for running_helpers to become zero before the setting of | |
5307427a | 316 | * usermodehelper_disabled in usermodehelper_disable() fails |
ccd4b65a RW |
317 | */ |
318 | #define RUNNING_HELPERS_TIMEOUT (5 * HZ) | |
319 | ||
b298d289 SB |
320 | void read_lock_usermodehelper(void) |
321 | { | |
322 | down_read(&umhelper_sem); | |
323 | } | |
324 | EXPORT_SYMBOL_GPL(read_lock_usermodehelper); | |
325 | ||
326 | void read_unlock_usermodehelper(void) | |
327 | { | |
328 | up_read(&umhelper_sem); | |
329 | } | |
330 | EXPORT_SYMBOL_GPL(read_unlock_usermodehelper); | |
331 | ||
1bfcf130 RW |
332 | /** |
333 | * usermodehelper_disable - prevent new helpers from being started | |
334 | */ | |
335 | int usermodehelper_disable(void) | |
8cdd4936 | 336 | { |
ccd4b65a RW |
337 | long retval; |
338 | ||
b298d289 | 339 | down_write(&umhelper_sem); |
1bfcf130 | 340 | usermodehelper_disabled = 1; |
b298d289 SB |
341 | up_write(&umhelper_sem); |
342 | ||
1bfcf130 RW |
343 | /* |
344 | * From now on call_usermodehelper_exec() won't start any new | |
345 | * helpers, so it is sufficient if running_helpers turns out to | |
346 | * be zero at one point (it may be increased later, but that | |
347 | * doesn't matter). | |
348 | */ | |
349 | retval = wait_event_timeout(running_helpers_waitq, | |
ccd4b65a RW |
350 | atomic_read(&running_helpers) == 0, |
351 | RUNNING_HELPERS_TIMEOUT); | |
1bfcf130 RW |
352 | if (retval) |
353 | return 0; | |
8cdd4936 | 354 | |
b298d289 | 355 | down_write(&umhelper_sem); |
1bfcf130 | 356 | usermodehelper_disabled = 0; |
b298d289 | 357 | up_write(&umhelper_sem); |
1bfcf130 RW |
358 | return -EAGAIN; |
359 | } | |
360 | ||
361 | /** | |
362 | * usermodehelper_enable - allow new helpers to be started again | |
363 | */ | |
364 | void usermodehelper_enable(void) | |
365 | { | |
b298d289 | 366 | down_write(&umhelper_sem); |
1bfcf130 | 367 | usermodehelper_disabled = 0; |
b298d289 | 368 | up_write(&umhelper_sem); |
8cdd4936 RW |
369 | } |
370 | ||
a144c6a6 RW |
371 | /** |
372 | * usermodehelper_is_disabled - check if new helpers are allowed to be started | |
373 | */ | |
374 | bool usermodehelper_is_disabled(void) | |
375 | { | |
376 | return usermodehelper_disabled; | |
377 | } | |
378 | EXPORT_SYMBOL_GPL(usermodehelper_is_disabled); | |
379 | ||
ccd4b65a RW |
380 | static void helper_lock(void) |
381 | { | |
382 | atomic_inc(&running_helpers); | |
383 | smp_mb__after_atomic_inc(); | |
384 | } | |
385 | ||
386 | static void helper_unlock(void) | |
387 | { | |
388 | if (atomic_dec_and_test(&running_helpers)) | |
389 | wake_up(&running_helpers_waitq); | |
390 | } | |
ccd4b65a | 391 | |
1da177e4 | 392 | /** |
0ab4dc92 | 393 | * call_usermodehelper_setup - prepare to call a usermode helper |
61df47c8 RD |
394 | * @path: path to usermode executable |
395 | * @argv: arg vector for process | |
396 | * @envp: environment for process | |
ac331d15 | 397 | * @gfp_mask: gfp mask for memory allocation |
0ab4dc92 | 398 | * |
61df47c8 | 399 | * Returns either %NULL on allocation failure, or a subprocess_info |
0ab4dc92 JF |
400 | * structure. This should be passed to call_usermodehelper_exec to |
401 | * exec the process and free the structure. | |
402 | */ | |
ac331d15 KM |
403 | struct subprocess_info *call_usermodehelper_setup(char *path, char **argv, |
404 | char **envp, gfp_t gfp_mask) | |
0ab4dc92 JF |
405 | { |
406 | struct subprocess_info *sub_info; | |
ac331d15 | 407 | sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask); |
0ab4dc92 JF |
408 | if (!sub_info) |
409 | goto out; | |
410 | ||
411 | INIT_WORK(&sub_info->work, __call_usermodehelper); | |
412 | sub_info->path = path; | |
413 | sub_info->argv = argv; | |
414 | sub_info->envp = envp; | |
0ab4dc92 JF |
415 | out: |
416 | return sub_info; | |
417 | } | |
418 | EXPORT_SYMBOL(call_usermodehelper_setup); | |
419 | ||
0ab4dc92 | 420 | /** |
a06a4dc3 | 421 | * call_usermodehelper_setfns - set a cleanup/init function |
0ab4dc92 JF |
422 | * @info: a subprocess_info returned by call_usermodehelper_setup |
423 | * @cleanup: a cleanup function | |
a06a4dc3 NH |
424 | * @init: an init function |
425 | * @data: arbitrary context sensitive data | |
426 | * | |
427 | * The init function is used to customize the helper process prior to | |
428 | * exec. A non-zero return code causes the process to error out, exit, | |
429 | * and return the failure to the calling process | |
0ab4dc92 | 430 | * |
a06a4dc3 | 431 | * The cleanup function is just before ethe subprocess_info is about to |
0ab4dc92 JF |
432 | * be freed. This can be used for freeing the argv and envp. The |
433 | * Function must be runnable in either a process context or the | |
434 | * context in which call_usermodehelper_exec is called. | |
435 | */ | |
a06a4dc3 | 436 | void call_usermodehelper_setfns(struct subprocess_info *info, |
87966996 | 437 | int (*init)(struct subprocess_info *info, struct cred *new), |
a06a4dc3 NH |
438 | void (*cleanup)(struct subprocess_info *info), |
439 | void *data) | |
0ab4dc92 JF |
440 | { |
441 | info->cleanup = cleanup; | |
a06a4dc3 NH |
442 | info->init = init; |
443 | info->data = data; | |
0ab4dc92 | 444 | } |
a06a4dc3 | 445 | EXPORT_SYMBOL(call_usermodehelper_setfns); |
0ab4dc92 | 446 | |
0ab4dc92 JF |
447 | /** |
448 | * call_usermodehelper_exec - start a usermode application | |
449 | * @sub_info: information about the subprocessa | |
1da177e4 | 450 | * @wait: wait for the application to finish and return status. |
a98f0dd3 AK |
451 | * when -1 don't wait at all, but you get no useful error back when |
452 | * the program couldn't be exec'ed. This makes it safe to call | |
453 | * from interrupt context. | |
1da177e4 LT |
454 | * |
455 | * Runs a user-space application. The application is started | |
456 | * asynchronously if wait is not set, and runs as a child of keventd. | |
457 | * (ie. it runs with full root capabilities). | |
1da177e4 | 458 | */ |
9d944ef3 | 459 | int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) |
1da177e4 | 460 | { |
60be6b9a | 461 | DECLARE_COMPLETION_ONSTACK(done); |
78468033 | 462 | int retval = 0; |
1da177e4 | 463 | |
ccd4b65a | 464 | helper_lock(); |
78468033 | 465 | if (sub_info->path[0] == '\0') |
0ab4dc92 | 466 | goto out; |
1da177e4 | 467 | |
8cdd4936 | 468 | if (!khelper_wq || usermodehelper_disabled) { |
0ab4dc92 JF |
469 | retval = -EBUSY; |
470 | goto out; | |
471 | } | |
a98f0dd3 | 472 | |
a98f0dd3 | 473 | sub_info->complete = &done; |
a98f0dd3 AK |
474 | sub_info->wait = wait; |
475 | ||
476 | queue_work(khelper_wq, &sub_info->work); | |
78468033 NC |
477 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ |
478 | goto unlock; | |
d0bd587a ON |
479 | |
480 | if (wait & UMH_KILLABLE) { | |
481 | retval = wait_for_completion_killable(&done); | |
482 | if (!retval) | |
483 | goto wait_done; | |
484 | ||
485 | /* umh_complete() will see NULL and free sub_info */ | |
486 | if (xchg(&sub_info->complete, NULL)) | |
487 | goto unlock; | |
488 | /* fallthrough, umh_complete() was already called */ | |
489 | } | |
490 | ||
1da177e4 | 491 | wait_for_completion(&done); |
d0bd587a | 492 | wait_done: |
a98f0dd3 | 493 | retval = sub_info->retval; |
78468033 | 494 | out: |
0ab4dc92 | 495 | call_usermodehelper_freeinfo(sub_info); |
78468033 | 496 | unlock: |
ccd4b65a | 497 | helper_unlock(); |
a98f0dd3 | 498 | return retval; |
1da177e4 | 499 | } |
0ab4dc92 | 500 | EXPORT_SYMBOL(call_usermodehelper_exec); |
1da177e4 | 501 | |
17f60a7d EP |
502 | static int proc_cap_handler(struct ctl_table *table, int write, |
503 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
504 | { | |
505 | struct ctl_table t; | |
506 | unsigned long cap_array[_KERNEL_CAPABILITY_U32S]; | |
507 | kernel_cap_t new_cap; | |
508 | int err, i; | |
509 | ||
510 | if (write && (!capable(CAP_SETPCAP) || | |
511 | !capable(CAP_SYS_MODULE))) | |
512 | return -EPERM; | |
513 | ||
514 | /* | |
515 | * convert from the global kernel_cap_t to the ulong array to print to | |
516 | * userspace if this is a read. | |
517 | */ | |
518 | spin_lock(&umh_sysctl_lock); | |
519 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) { | |
520 | if (table->data == CAP_BSET) | |
521 | cap_array[i] = usermodehelper_bset.cap[i]; | |
522 | else if (table->data == CAP_PI) | |
523 | cap_array[i] = usermodehelper_inheritable.cap[i]; | |
524 | else | |
525 | BUG(); | |
526 | } | |
527 | spin_unlock(&umh_sysctl_lock); | |
528 | ||
529 | t = *table; | |
530 | t.data = &cap_array; | |
531 | ||
532 | /* | |
533 | * actually read or write and array of ulongs from userspace. Remember | |
534 | * these are least significant 32 bits first | |
535 | */ | |
536 | err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); | |
537 | if (err < 0) | |
538 | return err; | |
539 | ||
540 | /* | |
541 | * convert from the sysctl array of ulongs to the kernel_cap_t | |
542 | * internal representation | |
543 | */ | |
544 | for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) | |
545 | new_cap.cap[i] = cap_array[i]; | |
546 | ||
547 | /* | |
548 | * Drop everything not in the new_cap (but don't add things) | |
549 | */ | |
550 | spin_lock(&umh_sysctl_lock); | |
551 | if (write) { | |
552 | if (table->data == CAP_BSET) | |
553 | usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap); | |
554 | if (table->data == CAP_PI) | |
555 | usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap); | |
556 | } | |
557 | spin_unlock(&umh_sysctl_lock); | |
558 | ||
559 | return 0; | |
560 | } | |
561 | ||
562 | struct ctl_table usermodehelper_table[] = { | |
563 | { | |
564 | .procname = "bset", | |
565 | .data = CAP_BSET, | |
566 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
567 | .mode = 0600, | |
568 | .proc_handler = proc_cap_handler, | |
569 | }, | |
570 | { | |
571 | .procname = "inheritable", | |
572 | .data = CAP_PI, | |
573 | .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), | |
574 | .mode = 0600, | |
575 | .proc_handler = proc_cap_handler, | |
576 | }, | |
577 | { } | |
578 | }; | |
579 | ||
1da177e4 LT |
580 | void __init usermodehelper_init(void) |
581 | { | |
582 | khelper_wq = create_singlethread_workqueue("khelper"); | |
583 | BUG_ON(!khelper_wq); | |
584 | } |