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> |
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> |
1da177e4 LT |
36 | #include <asm/uaccess.h> |
37 | ||
38 | extern int max_threads; | |
39 | ||
40 | static struct workqueue_struct *khelper_wq; | |
41 | ||
42 | #ifdef CONFIG_KMOD | |
43 | ||
44 | /* | |
45 | modprobe_path is set via /proc/sys. | |
46 | */ | |
47 | char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe"; | |
48 | ||
49 | /** | |
50 | * request_module - try to load a kernel module | |
51 | * @fmt: printf style format string for the name of the module | |
52 | * @varargs: arguements as specified in the format string | |
53 | * | |
54 | * Load a module using the user mode module loader. The function returns | |
55 | * zero on success or a negative errno code on failure. Note that a | |
56 | * successful module load does not mean the module did not then unload | |
57 | * and exit on an error of its own. Callers must check that the service | |
58 | * they requested is now available not blindly invoke it. | |
59 | * | |
60 | * If module auto-loading support is disabled then this function | |
61 | * becomes a no-operation. | |
62 | */ | |
63 | int request_module(const char *fmt, ...) | |
64 | { | |
65 | va_list args; | |
66 | char module_name[MODULE_NAME_LEN]; | |
67 | unsigned int max_modprobes; | |
68 | int ret; | |
69 | char *argv[] = { modprobe_path, "-q", "--", module_name, NULL }; | |
70 | static char *envp[] = { "HOME=/", | |
71 | "TERM=linux", | |
72 | "PATH=/sbin:/usr/sbin:/bin:/usr/bin", | |
73 | NULL }; | |
74 | static atomic_t kmod_concurrent = ATOMIC_INIT(0); | |
75 | #define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */ | |
76 | static int kmod_loop_msg; | |
77 | ||
78 | va_start(args, fmt); | |
79 | ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args); | |
80 | va_end(args); | |
81 | if (ret >= MODULE_NAME_LEN) | |
82 | return -ENAMETOOLONG; | |
83 | ||
84 | /* If modprobe needs a service that is in a module, we get a recursive | |
85 | * loop. Limit the number of running kmod threads to max_threads/2 or | |
86 | * MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method | |
87 | * would be to run the parents of this process, counting how many times | |
88 | * kmod was invoked. That would mean accessing the internals of the | |
89 | * process tables to get the command line, proc_pid_cmdline is static | |
90 | * and it is not worth changing the proc code just to handle this case. | |
91 | * KAO. | |
92 | * | |
93 | * "trace the ppid" is simple, but will fail if someone's | |
94 | * parent exits. I think this is as good as it gets. --RR | |
95 | */ | |
96 | max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT); | |
97 | atomic_inc(&kmod_concurrent); | |
98 | if (atomic_read(&kmod_concurrent) > max_modprobes) { | |
99 | /* We may be blaming an innocent here, but unlikely */ | |
100 | if (kmod_loop_msg++ < 5) | |
101 | printk(KERN_ERR | |
102 | "request_module: runaway loop modprobe %s\n", | |
103 | module_name); | |
104 | atomic_dec(&kmod_concurrent); | |
105 | return -ENOMEM; | |
106 | } | |
107 | ||
108 | ret = call_usermodehelper(modprobe_path, argv, envp, 1); | |
109 | atomic_dec(&kmod_concurrent); | |
110 | return ret; | |
111 | } | |
112 | EXPORT_SYMBOL(request_module); | |
113 | #endif /* CONFIG_KMOD */ | |
114 | ||
115 | struct subprocess_info { | |
65f27f38 | 116 | struct work_struct work; |
1da177e4 LT |
117 | struct completion *complete; |
118 | char *path; | |
119 | char **argv; | |
120 | char **envp; | |
7888e7ff | 121 | struct key *ring; |
86313c48 | 122 | enum umh_wait wait; |
1da177e4 | 123 | int retval; |
e239ca54 | 124 | struct file *stdin; |
0ab4dc92 | 125 | void (*cleanup)(char **argv, char **envp); |
1da177e4 LT |
126 | }; |
127 | ||
128 | /* | |
129 | * This is the task which runs the usermode application | |
130 | */ | |
131 | static int ____call_usermodehelper(void *data) | |
132 | { | |
133 | struct subprocess_info *sub_info = data; | |
20e1129a | 134 | struct key *new_session, *old_session; |
1da177e4 LT |
135 | int retval; |
136 | ||
7888e7ff | 137 | /* Unblock all signals and set the session keyring. */ |
20e1129a | 138 | new_session = key_get(sub_info->ring); |
1da177e4 | 139 | spin_lock_irq(¤t->sighand->siglock); |
20e1129a | 140 | old_session = __install_session_keyring(current, new_session); |
1da177e4 LT |
141 | flush_signal_handlers(current, 1); |
142 | sigemptyset(¤t->blocked); | |
143 | recalc_sigpending(); | |
144 | spin_unlock_irq(¤t->sighand->siglock); | |
145 | ||
7888e7ff DH |
146 | key_put(old_session); |
147 | ||
e239ca54 AK |
148 | /* Install input pipe when needed */ |
149 | if (sub_info->stdin) { | |
150 | struct files_struct *f = current->files; | |
151 | struct fdtable *fdt; | |
152 | /* no races because files should be private here */ | |
153 | sys_close(0); | |
154 | fd_install(0, sub_info->stdin); | |
155 | spin_lock(&f->file_lock); | |
156 | fdt = files_fdtable(f); | |
157 | FD_SET(0, fdt->open_fds); | |
158 | FD_CLR(0, fdt->close_on_exec); | |
159 | spin_unlock(&f->file_lock); | |
d025c9db AK |
160 | |
161 | /* and disallow core files too */ | |
162 | current->signal->rlim[RLIMIT_CORE] = (struct rlimit){0, 0}; | |
e239ca54 AK |
163 | } |
164 | ||
1da177e4 LT |
165 | /* We can run anywhere, unlike our parent keventd(). */ |
166 | set_cpus_allowed(current, CPU_MASK_ALL); | |
167 | ||
b73a7e76 JE |
168 | /* |
169 | * Our parent is keventd, which runs with elevated scheduling priority. | |
170 | * Avoid propagating that into the userspace child. | |
171 | */ | |
172 | set_user_nice(current, 0); | |
173 | ||
1da177e4 LT |
174 | retval = -EPERM; |
175 | if (current->fs->root) | |
67608567 AB |
176 | retval = kernel_execve(sub_info->path, |
177 | sub_info->argv, sub_info->envp); | |
1da177e4 LT |
178 | |
179 | /* Exec failed? */ | |
180 | sub_info->retval = retval; | |
181 | do_exit(0); | |
182 | } | |
183 | ||
0ab4dc92 JF |
184 | void call_usermodehelper_freeinfo(struct subprocess_info *info) |
185 | { | |
186 | if (info->cleanup) | |
187 | (*info->cleanup)(info->argv, info->envp); | |
188 | kfree(info); | |
189 | } | |
190 | EXPORT_SYMBOL(call_usermodehelper_freeinfo); | |
191 | ||
1da177e4 LT |
192 | /* Keventd can't block, but this (a child) can. */ |
193 | static int wait_for_helper(void *data) | |
194 | { | |
195 | struct subprocess_info *sub_info = data; | |
196 | pid_t pid; | |
1da177e4 LT |
197 | |
198 | /* Install a handler: if SIGCLD isn't handled sys_wait4 won't | |
199 | * populate the status, but will return -ECHILD. */ | |
1da177e4 LT |
200 | allow_signal(SIGCHLD); |
201 | ||
202 | pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD); | |
203 | if (pid < 0) { | |
204 | sub_info->retval = pid; | |
205 | } else { | |
111dbe0c BS |
206 | int ret; |
207 | ||
1da177e4 LT |
208 | /* |
209 | * Normally it is bogus to call wait4() from in-kernel because | |
210 | * wait4() wants to write the exit code to a userspace address. | |
211 | * But wait_for_helper() always runs as keventd, and put_user() | |
212 | * to a kernel address works OK for kernel threads, due to their | |
213 | * having an mm_segment_t which spans the entire address space. | |
214 | * | |
215 | * Thus the __user pointer cast is valid here. | |
216 | */ | |
111dbe0c BS |
217 | sys_wait4(pid, (int __user *)&ret, 0, NULL); |
218 | ||
219 | /* | |
220 | * If ret is 0, either ____call_usermodehelper failed and the | |
221 | * real error code is already in sub_info->retval or | |
222 | * sub_info->retval is 0 anyway, so don't mess with it then. | |
223 | */ | |
224 | if (ret) | |
225 | sub_info->retval = ret; | |
1da177e4 LT |
226 | } |
227 | ||
86313c48 | 228 | if (sub_info->wait == UMH_NO_WAIT) |
0ab4dc92 | 229 | call_usermodehelper_freeinfo(sub_info); |
a98f0dd3 AK |
230 | else |
231 | complete(sub_info->complete); | |
1da177e4 LT |
232 | return 0; |
233 | } | |
234 | ||
235 | /* This is run by khelper thread */ | |
65f27f38 | 236 | static void __call_usermodehelper(struct work_struct *work) |
1da177e4 | 237 | { |
65f27f38 DH |
238 | struct subprocess_info *sub_info = |
239 | container_of(work, struct subprocess_info, work); | |
1da177e4 | 240 | pid_t pid; |
86313c48 | 241 | enum umh_wait wait = sub_info->wait; |
1da177e4 LT |
242 | |
243 | /* CLONE_VFORK: wait until the usermode helper has execve'd | |
244 | * successfully We need the data structures to stay around | |
245 | * until that is done. */ | |
86313c48 | 246 | if (wait == UMH_WAIT_PROC || wait == UMH_NO_WAIT) |
1da177e4 LT |
247 | pid = kernel_thread(wait_for_helper, sub_info, |
248 | CLONE_FS | CLONE_FILES | SIGCHLD); | |
249 | else | |
250 | pid = kernel_thread(____call_usermodehelper, sub_info, | |
251 | CLONE_VFORK | SIGCHLD); | |
252 | ||
86313c48 JF |
253 | switch (wait) { |
254 | case UMH_NO_WAIT: | |
255 | break; | |
a98f0dd3 | 256 | |
86313c48 JF |
257 | case UMH_WAIT_PROC: |
258 | if (pid > 0) | |
259 | break; | |
1da177e4 | 260 | sub_info->retval = pid; |
86313c48 JF |
261 | /* FALLTHROUGH */ |
262 | ||
263 | case UMH_WAIT_EXEC: | |
1da177e4 | 264 | complete(sub_info->complete); |
86313c48 | 265 | } |
1da177e4 LT |
266 | } |
267 | ||
268 | /** | |
0ab4dc92 JF |
269 | * call_usermodehelper_setup - prepare to call a usermode helper |
270 | * @path - path to usermode executable | |
271 | * @argv - arg vector for process | |
272 | * @envp - environment for process | |
273 | * | |
274 | * Returns either NULL on allocation failure, or a subprocess_info | |
275 | * structure. This should be passed to call_usermodehelper_exec to | |
276 | * exec the process and free the structure. | |
277 | */ | |
278 | struct subprocess_info *call_usermodehelper_setup(char *path, | |
279 | char **argv, char **envp) | |
280 | { | |
281 | struct subprocess_info *sub_info; | |
282 | sub_info = kzalloc(sizeof(struct subprocess_info), GFP_ATOMIC); | |
283 | if (!sub_info) | |
284 | goto out; | |
285 | ||
286 | INIT_WORK(&sub_info->work, __call_usermodehelper); | |
287 | sub_info->path = path; | |
288 | sub_info->argv = argv; | |
289 | sub_info->envp = envp; | |
290 | ||
291 | out: | |
292 | return sub_info; | |
293 | } | |
294 | EXPORT_SYMBOL(call_usermodehelper_setup); | |
295 | ||
296 | /** | |
297 | * call_usermodehelper_setkeys - set the session keys for usermode helper | |
298 | * @info: a subprocess_info returned by call_usermodehelper_setup | |
299 | * @session_keyring: the session keyring for the process | |
300 | */ | |
301 | void call_usermodehelper_setkeys(struct subprocess_info *info, | |
302 | struct key *session_keyring) | |
303 | { | |
304 | info->ring = session_keyring; | |
305 | } | |
306 | EXPORT_SYMBOL(call_usermodehelper_setkeys); | |
307 | ||
308 | /** | |
309 | * call_usermodehelper_setcleanup - set a cleanup function | |
310 | * @info: a subprocess_info returned by call_usermodehelper_setup | |
311 | * @cleanup: a cleanup function | |
312 | * | |
313 | * The cleanup function is just befor ethe subprocess_info is about to | |
314 | * be freed. This can be used for freeing the argv and envp. The | |
315 | * Function must be runnable in either a process context or the | |
316 | * context in which call_usermodehelper_exec is called. | |
317 | */ | |
318 | void call_usermodehelper_setcleanup(struct subprocess_info *info, | |
319 | void (*cleanup)(char **argv, char **envp)) | |
320 | { | |
321 | info->cleanup = cleanup; | |
322 | } | |
323 | EXPORT_SYMBOL(call_usermodehelper_setcleanup); | |
324 | ||
325 | /** | |
326 | * call_usermodehelper_stdinpipe - set up a pipe to be used for stdin | |
327 | * @sub_info: a subprocess_info returned by call_usermodehelper_setup | |
328 | * @filp: set to the write-end of a pipe | |
329 | * | |
330 | * This constructs a pipe, and sets the read end to be the stdin of the | |
331 | * subprocess, and returns the write-end in *@filp. | |
332 | */ | |
333 | int call_usermodehelper_stdinpipe(struct subprocess_info *sub_info, | |
334 | struct file **filp) | |
335 | { | |
336 | struct file *f; | |
337 | ||
338 | f = create_write_pipe(); | |
339 | if (IS_ERR(f)) | |
340 | return PTR_ERR(f); | |
341 | *filp = f; | |
342 | ||
343 | f = create_read_pipe(f); | |
344 | if (IS_ERR(f)) { | |
345 | free_write_pipe(*filp); | |
346 | return PTR_ERR(f); | |
347 | } | |
348 | sub_info->stdin = f; | |
349 | ||
350 | return 0; | |
351 | } | |
352 | EXPORT_SYMBOL(call_usermodehelper_stdinpipe); | |
353 | ||
354 | /** | |
355 | * call_usermodehelper_exec - start a usermode application | |
356 | * @sub_info: information about the subprocessa | |
1da177e4 | 357 | * @wait: wait for the application to finish and return status. |
a98f0dd3 AK |
358 | * when -1 don't wait at all, but you get no useful error back when |
359 | * the program couldn't be exec'ed. This makes it safe to call | |
360 | * from interrupt context. | |
1da177e4 LT |
361 | * |
362 | * Runs a user-space application. The application is started | |
363 | * asynchronously if wait is not set, and runs as a child of keventd. | |
364 | * (ie. it runs with full root capabilities). | |
1da177e4 | 365 | */ |
0ab4dc92 | 366 | int call_usermodehelper_exec(struct subprocess_info *sub_info, |
86313c48 | 367 | enum umh_wait wait) |
1da177e4 | 368 | { |
60be6b9a | 369 | DECLARE_COMPLETION_ONSTACK(done); |
a98f0dd3 | 370 | int retval; |
1da177e4 | 371 | |
0ab4dc92 JF |
372 | if (sub_info->path[0] == '\0') { |
373 | retval = 0; | |
374 | goto out; | |
375 | } | |
1da177e4 | 376 | |
0ab4dc92 JF |
377 | if (!khelper_wq) { |
378 | retval = -EBUSY; | |
379 | goto out; | |
380 | } | |
a98f0dd3 | 381 | |
a98f0dd3 | 382 | sub_info->complete = &done; |
a98f0dd3 AK |
383 | sub_info->wait = wait; |
384 | ||
385 | queue_work(khelper_wq, &sub_info->work); | |
86313c48 | 386 | if (wait == UMH_NO_WAIT) /* task has freed sub_info */ |
a98f0dd3 | 387 | return 0; |
1da177e4 | 388 | wait_for_completion(&done); |
a98f0dd3 | 389 | retval = sub_info->retval; |
0ab4dc92 JF |
390 | |
391 | out: | |
392 | call_usermodehelper_freeinfo(sub_info); | |
a98f0dd3 | 393 | return retval; |
1da177e4 | 394 | } |
0ab4dc92 | 395 | EXPORT_SYMBOL(call_usermodehelper_exec); |
1da177e4 | 396 | |
0ab4dc92 JF |
397 | /** |
398 | * call_usermodehelper_pipe - call a usermode helper process with a pipe stdin | |
399 | * @path: path to usermode executable | |
400 | * @argv: arg vector for process | |
401 | * @envp: environment for process | |
402 | * @filp: set to the write-end of a pipe | |
403 | * | |
404 | * This is a simple wrapper which executes a usermode-helper function | |
405 | * with a pipe as stdin. It is implemented entirely in terms of | |
406 | * lower-level call_usermodehelper_* functions. | |
407 | */ | |
e239ca54 AK |
408 | int call_usermodehelper_pipe(char *path, char **argv, char **envp, |
409 | struct file **filp) | |
410 | { | |
0ab4dc92 JF |
411 | struct subprocess_info *sub_info; |
412 | int ret; | |
e239ca54 | 413 | |
0ab4dc92 JF |
414 | sub_info = call_usermodehelper_setup(path, argv, envp); |
415 | if (sub_info == NULL) | |
416 | return -ENOMEM; | |
e239ca54 | 417 | |
0ab4dc92 JF |
418 | ret = call_usermodehelper_stdinpipe(sub_info, filp); |
419 | if (ret < 0) | |
420 | goto out; | |
e239ca54 | 421 | |
0ab4dc92 | 422 | return call_usermodehelper_exec(sub_info, 1); |
e239ca54 | 423 | |
0ab4dc92 JF |
424 | out: |
425 | call_usermodehelper_freeinfo(sub_info); | |
426 | return ret; | |
e239ca54 AK |
427 | } |
428 | EXPORT_SYMBOL(call_usermodehelper_pipe); | |
429 | ||
1da177e4 LT |
430 | void __init usermodehelper_init(void) |
431 | { | |
432 | khelper_wq = create_singlethread_workqueue("khelper"); | |
433 | BUG_ON(!khelper_wq); | |
434 | } |