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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> |
6b3286ed | 27 | #include <linux/mnt_namespace.h> |
1da177e4 LT |
28 | #include <linux/completion.h> |
29 | #include <linux/file.h> | |
30 | #include <linux/workqueue.h> | |
31 | #include <linux/security.h> | |
32 | #include <linux/mount.h> | |
33 | #include <linux/kernel.h> | |
34 | #include <linux/init.h> | |
d025c9db | 35 | #include <linux/resource.h> |
8cdd4936 RW |
36 | #include <linux/notifier.h> |
37 | #include <linux/suspend.h> | |
1da177e4 LT |
38 | #include <asm/uaccess.h> |
39 | ||
40 | extern int max_threads; | |
41 | ||
42 | static struct workqueue_struct *khelper_wq; | |
43 | ||
8cdd4936 RW |
44 | /* |
45 | * If set, both call_usermodehelper_keys() and call_usermodehelper_pipe() exit | |
46 | * immediately returning -EBUSY. Used for preventing user land processes from | |
47 | * being created after the user land has been frozen during a system-wide | |
48 | * hibernation or suspend operation. | |
49 | */ | |
50 | static int usermodehelper_disabled; | |
51 | ||
1da177e4 LT |
52 | #ifdef CONFIG_KMOD |
53 | ||
54 | /* | |
55 | modprobe_path is set via /proc/sys. | |
56 | */ | |
57 | char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe"; | |
58 | ||
59 | /** | |
60 | * request_module - try to load a kernel module | |
61 | * @fmt: printf style format string for the name of the module | |
62 | * @varargs: arguements as specified in the format string | |
63 | * | |
64 | * Load a module using the user mode module loader. The function returns | |
65 | * zero on success or a negative errno code on failure. Note that a | |
66 | * successful module load does not mean the module did not then unload | |
67 | * and exit on an error of its own. Callers must check that the service | |
68 | * they requested is now available not blindly invoke it. | |
69 | * | |
70 | * If module auto-loading support is disabled then this function | |
71 | * becomes a no-operation. | |
72 | */ | |
73 | int request_module(const char *fmt, ...) | |
74 | { | |
75 | va_list args; | |
76 | char module_name[MODULE_NAME_LEN]; | |
77 | unsigned int max_modprobes; | |
78 | int ret; | |
79 | char *argv[] = { modprobe_path, "-q", "--", module_name, NULL }; | |
80 | static char *envp[] = { "HOME=/", | |
81 | "TERM=linux", | |
82 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
83 | NULL }; | |
84 | static atomic_t kmod_concurrent = ATOMIC_INIT(0); | |
85 | #define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */ | |
86 | static int kmod_loop_msg; | |
87 | ||
88 | va_start(args, fmt); | |
89 | ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args); | |
90 | va_end(args); | |
91 | if (ret >= MODULE_NAME_LEN) | |
92 | return -ENAMETOOLONG; | |
93 | ||
94 | /* If modprobe needs a service that is in a module, we get a recursive | |
95 | * loop. Limit the number of running kmod threads to max_threads/2 or | |
96 | * MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method | |
97 | * would be to run the parents of this process, counting how many times | |
98 | * kmod was invoked. That would mean accessing the internals of the | |
99 | * process tables to get the command line, proc_pid_cmdline is static | |
100 | * and it is not worth changing the proc code just to handle this case. | |
101 | * KAO. | |
102 | * | |
103 | * "trace the ppid" is simple, but will fail if someone's | |
104 | * parent exits. I think this is as good as it gets. --RR | |
105 | */ | |
106 | max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT); | |
107 | atomic_inc(&kmod_concurrent); | |
108 | if (atomic_read(&kmod_concurrent) > max_modprobes) { | |
109 | /* We may be blaming an innocent here, but unlikely */ | |
110 | if (kmod_loop_msg++ < 5) | |
111 | printk(KERN_ERR | |
112 | "request_module: runaway loop modprobe %s\n", | |
113 | module_name); | |
114 | atomic_dec(&kmod_concurrent); | |
115 | return -ENOMEM; | |
116 | } | |
117 | ||
118 | ret = call_usermodehelper(modprobe_path, argv, envp, 1); | |
119 | atomic_dec(&kmod_concurrent); | |
120 | return ret; | |
121 | } | |
122 | EXPORT_SYMBOL(request_module); | |
123 | #endif /* CONFIG_KMOD */ | |
124 | ||
125 | struct subprocess_info { | |
65f27f38 | 126 | struct work_struct work; |
1da177e4 LT |
127 | struct completion *complete; |
128 | char *path; | |
129 | char **argv; | |
130 | char **envp; | |
7888e7ff | 131 | struct key *ring; |
86313c48 | 132 | enum umh_wait wait; |
1da177e4 | 133 | int retval; |
e239ca54 | 134 | struct file *stdin; |
0ab4dc92 | 135 | void (*cleanup)(char **argv, char **envp); |
1da177e4 LT |
136 | }; |
137 | ||
138 | /* | |
139 | * This is the task which runs the usermode application | |
140 | */ | |
141 | static int ____call_usermodehelper(void *data) | |
142 | { | |
143 | struct subprocess_info *sub_info = data; | |
20e1129a | 144 | struct key *new_session, *old_session; |
1da177e4 LT |
145 | int retval; |
146 | ||
7888e7ff | 147 | /* Unblock all signals and set the session keyring. */ |
20e1129a | 148 | new_session = key_get(sub_info->ring); |
1da177e4 | 149 | spin_lock_irq(¤t->sighand->siglock); |
20e1129a | 150 | old_session = __install_session_keyring(current, new_session); |
1da177e4 LT |
151 | flush_signal_handlers(current, 1); |
152 | sigemptyset(¤t->blocked); | |
153 | recalc_sigpending(); | |
154 | spin_unlock_irq(¤t->sighand->siglock); | |
155 | ||
7888e7ff DH |
156 | key_put(old_session); |
157 | ||
e239ca54 AK |
158 | /* Install input pipe when needed */ |
159 | if (sub_info->stdin) { | |
160 | struct files_struct *f = current->files; | |
161 | struct fdtable *fdt; | |
162 | /* no races because files should be private here */ | |
163 | sys_close(0); | |
164 | fd_install(0, sub_info->stdin); | |
165 | spin_lock(&f->file_lock); | |
166 | fdt = files_fdtable(f); | |
167 | FD_SET(0, fdt->open_fds); | |
168 | FD_CLR(0, fdt->close_on_exec); | |
169 | spin_unlock(&f->file_lock); | |
d025c9db AK |
170 | |
171 | /* and disallow core files too */ | |
172 | current->signal->rlim[RLIMIT_CORE] = (struct rlimit){0, 0}; | |
e239ca54 AK |
173 | } |
174 | ||
1da177e4 LT |
175 | /* We can run anywhere, unlike our parent keventd(). */ |
176 | set_cpus_allowed(current, CPU_MASK_ALL); | |
177 | ||
b73a7e76 JE |
178 | /* |
179 | * Our parent is keventd, which runs with elevated scheduling priority. | |
180 | * Avoid propagating that into the userspace child. | |
181 | */ | |
182 | set_user_nice(current, 0); | |
183 | ||
1da177e4 LT |
184 | retval = -EPERM; |
185 | if (current->fs->root) | |
67608567 AB |
186 | retval = kernel_execve(sub_info->path, |
187 | sub_info->argv, sub_info->envp); | |
1da177e4 LT |
188 | |
189 | /* Exec failed? */ | |
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) | |
197 | (*info->cleanup)(info->argv, info->envp); | |
198 | kfree(info); | |
199 | } | |
200 | EXPORT_SYMBOL(call_usermodehelper_freeinfo); | |
201 | ||
1da177e4 LT |
202 | /* Keventd can't block, but this (a child) can. */ |
203 | static int wait_for_helper(void *data) | |
204 | { | |
205 | struct subprocess_info *sub_info = data; | |
206 | pid_t pid; | |
1da177e4 LT |
207 | |
208 | /* Install a handler: if SIGCLD isn't handled sys_wait4 won't | |
209 | * populate the status, but will return -ECHILD. */ | |
1da177e4 LT |
210 | allow_signal(SIGCHLD); |
211 | ||
212 | pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD); | |
213 | if (pid < 0) { | |
214 | sub_info->retval = pid; | |
215 | } else { | |
111dbe0c BS |
216 | int ret; |
217 | ||
1da177e4 LT |
218 | /* |
219 | * Normally it is bogus to call wait4() from in-kernel because | |
220 | * wait4() wants to write the exit code to a userspace address. | |
221 | * But wait_for_helper() always runs as keventd, and put_user() | |
222 | * to a kernel address works OK for kernel threads, due to their | |
223 | * having an mm_segment_t which spans the entire address space. | |
224 | * | |
225 | * Thus the __user pointer cast is valid here. | |
226 | */ | |
111dbe0c BS |
227 | sys_wait4(pid, (int __user *)&ret, 0, NULL); |
228 | ||
229 | /* | |
230 | * If ret is 0, either ____call_usermodehelper failed and the | |
231 | * real error code is already in sub_info->retval or | |
232 | * sub_info->retval is 0 anyway, so don't mess with it then. | |
233 | */ | |
234 | if (ret) | |
235 | sub_info->retval = ret; | |
1da177e4 LT |
236 | } |
237 | ||
86313c48 | 238 | if (sub_info->wait == UMH_NO_WAIT) |
0ab4dc92 | 239 | call_usermodehelper_freeinfo(sub_info); |
a98f0dd3 AK |
240 | else |
241 | complete(sub_info->complete); | |
1da177e4 LT |
242 | return 0; |
243 | } | |
244 | ||
245 | /* This is run by khelper thread */ | |
65f27f38 | 246 | static void __call_usermodehelper(struct work_struct *work) |
1da177e4 | 247 | { |
65f27f38 DH |
248 | struct subprocess_info *sub_info = |
249 | container_of(work, struct subprocess_info, work); | |
1da177e4 | 250 | pid_t pid; |
86313c48 | 251 | enum umh_wait wait = sub_info->wait; |
1da177e4 LT |
252 | |
253 | /* CLONE_VFORK: wait until the usermode helper has execve'd | |
254 | * successfully We need the data structures to stay around | |
255 | * until that is done. */ | |
86313c48 | 256 | if (wait == UMH_WAIT_PROC || wait == UMH_NO_WAIT) |
1da177e4 LT |
257 | pid = kernel_thread(wait_for_helper, sub_info, |
258 | CLONE_FS | CLONE_FILES | SIGCHLD); | |
259 | else | |
260 | pid = kernel_thread(____call_usermodehelper, sub_info, | |
261 | CLONE_VFORK | SIGCHLD); | |
262 | ||
86313c48 JF |
263 | switch (wait) { |
264 | case UMH_NO_WAIT: | |
265 | break; | |
a98f0dd3 | 266 | |
86313c48 JF |
267 | case UMH_WAIT_PROC: |
268 | if (pid > 0) | |
269 | break; | |
1da177e4 | 270 | sub_info->retval = pid; |
86313c48 JF |
271 | /* FALLTHROUGH */ |
272 | ||
273 | case UMH_WAIT_EXEC: | |
1da177e4 | 274 | complete(sub_info->complete); |
86313c48 | 275 | } |
1da177e4 LT |
276 | } |
277 | ||
8cdd4936 RW |
278 | static int usermodehelper_pm_callback(struct notifier_block *nfb, |
279 | unsigned long action, | |
280 | void *ignored) | |
281 | { | |
282 | switch (action) { | |
283 | case PM_HIBERNATION_PREPARE: | |
284 | case PM_SUSPEND_PREPARE: | |
285 | usermodehelper_disabled = 1; | |
286 | return NOTIFY_OK; | |
287 | case PM_POST_HIBERNATION: | |
288 | case PM_POST_SUSPEND: | |
289 | usermodehelper_disabled = 0; | |
290 | return NOTIFY_OK; | |
291 | } | |
292 | ||
293 | return NOTIFY_DONE; | |
294 | } | |
295 | ||
1da177e4 | 296 | /** |
0ab4dc92 JF |
297 | * call_usermodehelper_setup - prepare to call a usermode helper |
298 | * @path - path to usermode executable | |
299 | * @argv - arg vector for process | |
300 | * @envp - environment for process | |
301 | * | |
302 | * Returns either NULL on allocation failure, or a subprocess_info | |
303 | * structure. This should be passed to call_usermodehelper_exec to | |
304 | * exec the process and free the structure. | |
305 | */ | |
306 | struct subprocess_info *call_usermodehelper_setup(char *path, | |
307 | char **argv, char **envp) | |
308 | { | |
309 | struct subprocess_info *sub_info; | |
310 | sub_info = kzalloc(sizeof(struct subprocess_info), GFP_ATOMIC); | |
311 | if (!sub_info) | |
312 | goto out; | |
313 | ||
314 | INIT_WORK(&sub_info->work, __call_usermodehelper); | |
315 | sub_info->path = path; | |
316 | sub_info->argv = argv; | |
317 | sub_info->envp = envp; | |
318 | ||
319 | out: | |
320 | return sub_info; | |
321 | } | |
322 | EXPORT_SYMBOL(call_usermodehelper_setup); | |
323 | ||
324 | /** | |
325 | * call_usermodehelper_setkeys - set the session keys for usermode helper | |
326 | * @info: a subprocess_info returned by call_usermodehelper_setup | |
327 | * @session_keyring: the session keyring for the process | |
328 | */ | |
329 | void call_usermodehelper_setkeys(struct subprocess_info *info, | |
330 | struct key *session_keyring) | |
331 | { | |
332 | info->ring = session_keyring; | |
333 | } | |
334 | EXPORT_SYMBOL(call_usermodehelper_setkeys); | |
335 | ||
336 | /** | |
337 | * call_usermodehelper_setcleanup - set a cleanup function | |
338 | * @info: a subprocess_info returned by call_usermodehelper_setup | |
339 | * @cleanup: a cleanup function | |
340 | * | |
341 | * The cleanup function is just befor ethe subprocess_info is about to | |
342 | * be freed. This can be used for freeing the argv and envp. The | |
343 | * Function must be runnable in either a process context or the | |
344 | * context in which call_usermodehelper_exec is called. | |
345 | */ | |
346 | void call_usermodehelper_setcleanup(struct subprocess_info *info, | |
347 | void (*cleanup)(char **argv, char **envp)) | |
348 | { | |
349 | info->cleanup = cleanup; | |
350 | } | |
351 | EXPORT_SYMBOL(call_usermodehelper_setcleanup); | |
352 | ||
353 | /** | |
354 | * call_usermodehelper_stdinpipe - set up a pipe to be used for stdin | |
355 | * @sub_info: a subprocess_info returned by call_usermodehelper_setup | |
356 | * @filp: set to the write-end of a pipe | |
357 | * | |
358 | * This constructs a pipe, and sets the read end to be the stdin of the | |
359 | * subprocess, and returns the write-end in *@filp. | |
360 | */ | |
361 | int call_usermodehelper_stdinpipe(struct subprocess_info *sub_info, | |
362 | struct file **filp) | |
363 | { | |
364 | struct file *f; | |
365 | ||
366 | f = create_write_pipe(); | |
367 | if (IS_ERR(f)) | |
368 | return PTR_ERR(f); | |
369 | *filp = f; | |
370 | ||
371 | f = create_read_pipe(f); | |
372 | if (IS_ERR(f)) { | |
373 | free_write_pipe(*filp); | |
374 | return PTR_ERR(f); | |
375 | } | |
376 | sub_info->stdin = f; | |
377 | ||
378 | return 0; | |
379 | } | |
380 | EXPORT_SYMBOL(call_usermodehelper_stdinpipe); | |
381 | ||
382 | /** | |
383 | * call_usermodehelper_exec - start a usermode application | |
384 | * @sub_info: information about the subprocessa | |
1da177e4 | 385 | * @wait: wait for the application to finish and return status. |
a98f0dd3 AK |
386 | * when -1 don't wait at all, but you get no useful error back when |
387 | * the program couldn't be exec'ed. This makes it safe to call | |
388 | * from interrupt context. | |
1da177e4 LT |
389 | * |
390 | * Runs a user-space application. The application is started | |
391 | * asynchronously if wait is not set, and runs as a child of keventd. | |
392 | * (ie. it runs with full root capabilities). | |
1da177e4 | 393 | */ |
0ab4dc92 | 394 | int call_usermodehelper_exec(struct subprocess_info *sub_info, |
86313c48 | 395 | enum umh_wait wait) |
1da177e4 | 396 | { |
60be6b9a | 397 | DECLARE_COMPLETION_ONSTACK(done); |
a98f0dd3 | 398 | int retval; |
1da177e4 | 399 | |
0ab4dc92 JF |
400 | if (sub_info->path[0] == '\0') { |
401 | retval = 0; | |
402 | goto out; | |
403 | } | |
1da177e4 | 404 | |
8cdd4936 | 405 | if (!khelper_wq || usermodehelper_disabled) { |
0ab4dc92 JF |
406 | retval = -EBUSY; |
407 | goto out; | |
408 | } | |
a98f0dd3 | 409 | |
a98f0dd3 | 410 | sub_info->complete = &done; |
a98f0dd3 AK |
411 | sub_info->wait = wait; |
412 | ||
413 | queue_work(khelper_wq, &sub_info->work); | |
86313c48 | 414 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ |
a98f0dd3 | 415 | return 0; |
1da177e4 | 416 | wait_for_completion(&done); |
a98f0dd3 | 417 | retval = sub_info->retval; |
0ab4dc92 JF |
418 | |
419 | out: | |
420 | call_usermodehelper_freeinfo(sub_info); | |
a98f0dd3 | 421 | return retval; |
1da177e4 | 422 | } |
0ab4dc92 | 423 | EXPORT_SYMBOL(call_usermodehelper_exec); |
1da177e4 | 424 | |
0ab4dc92 JF |
425 | /** |
426 | * call_usermodehelper_pipe - call a usermode helper process with a pipe stdin | |
427 | * @path: path to usermode executable | |
428 | * @argv: arg vector for process | |
429 | * @envp: environment for process | |
430 | * @filp: set to the write-end of a pipe | |
431 | * | |
432 | * This is a simple wrapper which executes a usermode-helper function | |
433 | * with a pipe as stdin. It is implemented entirely in terms of | |
434 | * lower-level call_usermodehelper_* functions. | |
435 | */ | |
e239ca54 AK |
436 | int call_usermodehelper_pipe(char *path, char **argv, char **envp, |
437 | struct file **filp) | |
438 | { | |
0ab4dc92 JF |
439 | struct subprocess_info *sub_info; |
440 | int ret; | |
e239ca54 | 441 | |
0ab4dc92 JF |
442 | sub_info = call_usermodehelper_setup(path, argv, envp); |
443 | if (sub_info == NULL) | |
444 | return -ENOMEM; | |
e239ca54 | 445 | |
0ab4dc92 JF |
446 | ret = call_usermodehelper_stdinpipe(sub_info, filp); |
447 | if (ret < 0) | |
448 | goto out; | |
e239ca54 | 449 | |
0ab4dc92 | 450 | return call_usermodehelper_exec(sub_info, 1); |
e239ca54 | 451 | |
0ab4dc92 JF |
452 | out: |
453 | call_usermodehelper_freeinfo(sub_info); | |
454 | return ret; | |
e239ca54 AK |
455 | } |
456 | EXPORT_SYMBOL(call_usermodehelper_pipe); | |
457 | ||
1da177e4 LT |
458 | void __init usermodehelper_init(void) |
459 | { | |
460 | khelper_wq = create_singlethread_workqueue("khelper"); | |
461 | BUG_ON(!khelper_wq); | |
8cdd4936 | 462 | pm_notifier(usermodehelper_pm_callback, 0); |
1da177e4 | 463 | } |