blob: b6e5ca9c758a54cac68805cf1c840ca0b8cd107f [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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*/
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/module.h>
22#include <linux/sched.h>
23#include <linux/syscalls.h>
24#include <linux/unistd.h>
25#include <linux/kmod.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <linux/completion.h>
Eric Paris17f60a72011-04-01 17:07:50 -040028#include <linux/cred.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/file.h>
Al Viro9f3acc32008-04-24 07:44:08 -040030#include <linux/fdtable.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <linux/workqueue.h>
32#include <linux/security.h>
33#include <linux/mount.h>
34#include <linux/kernel.h>
35#include <linux/init.h>
Andi Kleend025c9d2006-09-30 23:29:28 -070036#include <linux/resource.h>
Rafael J. Wysocki8cdd4932007-07-19 01:47:36 -070037#include <linux/notifier.h>
38#include <linux/suspend.h>
Srivatsa S. Bhatb298d282011-12-09 23:36:36 +010039#include <linux/rwsem.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070040#include <asm/uaccess.h>
41
Li Zefan7ead8b82009-08-17 16:56:28 +080042#include <trace/events/module.h>
43
Linus Torvalds1da177e2005-04-16 15:20:36 -070044extern int max_threads;
45
46static struct workqueue_struct *khelper_wq;
47
Tetsuo Handa0f207842012-07-30 14:42:20 -070048/*
49 * kmod_thread_locker is used for deadlock avoidance. There is no explicit
50 * locking to protect this global - it is private to the singleton khelper
51 * thread and should only ever be modified by that thread.
52 */
53static const struct task_struct *kmod_thread_locker;
54
Eric Paris17f60a72011-04-01 17:07:50 -040055#define CAP_BSET (void *)1
56#define CAP_PI (void *)2
57
58static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
59static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
60static DEFINE_SPINLOCK(umh_sysctl_lock);
Srivatsa S. Bhatb298d282011-12-09 23:36:36 +010061static DECLARE_RWSEM(umhelper_sem);
Eric Paris17f60a72011-04-01 17:07:50 -040062
Johannes Berga1ef5ad2008-07-08 19:00:17 +020063#ifdef CONFIG_MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -070064
65/*
66 modprobe_path is set via /proc/sys.
67*/
68char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
69
Oleg Nesterov1cc684a2012-03-23 15:02:50 -070070static void free_modprobe_argv(struct subprocess_info *info)
71{
72 kfree(info->argv[3]); /* check call_modprobe() */
73 kfree(info->argv);
74}
75
Oleg Nesterov3e63a932012-03-23 15:02:49 -070076static int call_modprobe(char *module_name, int wait)
77{
78 static char *envp[] = {
79 "HOME=/",
80 "TERM=linux",
81 "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
82 NULL
83 };
84
Oleg Nesterov1cc684a2012-03-23 15:02:50 -070085 char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL);
86 if (!argv)
87 goto out;
88
89 module_name = kstrdup(module_name, GFP_KERNEL);
90 if (!module_name)
91 goto free_argv;
92
93 argv[0] = modprobe_path;
94 argv[1] = "-q";
95 argv[2] = "--";
96 argv[3] = module_name; /* check free_modprobe_argv() */
97 argv[4] = NULL;
Oleg Nesterov3e63a932012-03-23 15:02:49 -070098
99 return call_usermodehelper_fns(modprobe_path, argv, envp,
Oleg Nesterov1cc684a2012-03-23 15:02:50 -0700100 wait | UMH_KILLABLE, NULL, free_modprobe_argv, NULL);
101free_argv:
102 kfree(argv);
103out:
104 return -ENOMEM;
Oleg Nesterov3e63a932012-03-23 15:02:49 -0700105}
106
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107/**
Arjan van de Venacae0512009-02-08 10:42:01 -0800108 * __request_module - try to load a kernel module
109 * @wait: wait (or not) for the operation to complete
Randy Dunlapbd4207c2009-01-06 14:42:39 -0800110 * @fmt: printf style format string for the name of the module
111 * @...: arguments as specified in the format string
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 *
113 * Load a module using the user mode module loader. The function returns
114 * zero on success or a negative errno code on failure. Note that a
115 * successful module load does not mean the module did not then unload
116 * and exit on an error of its own. Callers must check that the service
117 * they requested is now available not blindly invoke it.
118 *
119 * If module auto-loading support is disabled then this function
120 * becomes a no-operation.
121 */
Arjan van de Venacae0512009-02-08 10:42:01 -0800122int __request_module(bool wait, const char *fmt, ...)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123{
124 va_list args;
125 char module_name[MODULE_NAME_LEN];
126 unsigned int max_modprobes;
127 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 static atomic_t kmod_concurrent = ATOMIC_INIT(0);
129#define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */
130 static int kmod_loop_msg;
131
132 va_start(args, fmt);
133 ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
134 va_end(args);
135 if (ret >= MODULE_NAME_LEN)
136 return -ENAMETOOLONG;
137
Eric Parisdd8dbf22009-11-03 16:35:32 +1100138 ret = security_kernel_module_request(module_name);
139 if (ret)
140 return ret;
141
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 /* If modprobe needs a service that is in a module, we get a recursive
143 * loop. Limit the number of running kmod threads to max_threads/2 or
144 * MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method
145 * would be to run the parents of this process, counting how many times
146 * kmod was invoked. That would mean accessing the internals of the
147 * process tables to get the command line, proc_pid_cmdline is static
148 * and it is not worth changing the proc code just to handle this case.
149 * KAO.
150 *
151 * "trace the ppid" is simple, but will fail if someone's
152 * parent exits. I think this is as good as it gets. --RR
153 */
154 max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
155 atomic_inc(&kmod_concurrent);
156 if (atomic_read(&kmod_concurrent) > max_modprobes) {
157 /* We may be blaming an innocent here, but unlikely */
Jiri Kosina37252db2011-10-26 13:10:39 +1030158 if (kmod_loop_msg < 5) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 printk(KERN_ERR
160 "request_module: runaway loop modprobe %s\n",
161 module_name);
Jiri Kosina37252db2011-10-26 13:10:39 +1030162 kmod_loop_msg++;
163 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 atomic_dec(&kmod_concurrent);
165 return -ENOMEM;
166 }
167
Li Zefan7ead8b82009-08-17 16:56:28 +0800168 trace_module_request(module_name, wait, _RET_IP_);
169
Oleg Nesterov3e63a932012-03-23 15:02:49 -0700170 ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
Neil Hormana06a4dc2010-05-26 14:42:58 -0700171
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 atomic_dec(&kmod_concurrent);
173 return ret;
174}
Arjan van de Venacae0512009-02-08 10:42:01 -0800175EXPORT_SYMBOL(__request_module);
Rusty Russell118a9062008-10-17 02:38:36 -0500176#endif /* CONFIG_MODULES */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178/*
179 * This is the task which runs the usermode application
180 */
181static int ____call_usermodehelper(void *data)
182{
183 struct subprocess_info *sub_info = data;
Eric Paris17f60a72011-04-01 17:07:50 -0400184 struct cred *new;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 int retval;
186
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 spin_lock_irq(&current->sighand->siglock);
188 flush_signal_handlers(current, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 spin_unlock_irq(&current->sighand->siglock);
190
191 /* We can run anywhere, unlike our parent keventd(). */
Rusty Russell1a2142a2009-03-30 22:05:10 -0600192 set_cpus_allowed_ptr(current, cpu_all_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193
Jan Engelhardtb73a7e72007-05-08 00:28:24 -0700194 /*
195 * Our parent is keventd, which runs with elevated scheduling priority.
196 * Avoid propagating that into the userspace child.
197 */
198 set_user_nice(current, 0);
199
Eric Paris17f60a72011-04-01 17:07:50 -0400200 retval = -ENOMEM;
201 new = prepare_kernel_cred(current);
202 if (!new)
203 goto fail;
204
205 spin_lock(&umh_sysctl_lock);
206 new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
207 new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
208 new->cap_inheritable);
209 spin_unlock(&umh_sysctl_lock);
210
David Howells87966992011-06-17 11:25:59 +0100211 if (sub_info->init) {
212 retval = sub_info->init(sub_info, new);
213 if (retval) {
214 abort_creds(new);
215 goto fail;
216 }
217 }
218
Eric Paris17f60a72011-04-01 17:07:50 -0400219 commit_creds(new);
220
David Howellsd7627462010-08-17 23:52:56 +0100221 retval = kernel_execve(sub_info->path,
222 (const char *const *)sub_info->argv,
223 (const char *const *)sub_info->envp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224
225 /* Exec failed? */
Neil Hormana06a4dc2010-05-26 14:42:58 -0700226fail:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 sub_info->retval = retval;
Al Virofb455502012-10-10 20:09:44 -0400228 do_exit(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229}
230
Tetsuo Handa0f207842012-07-30 14:42:20 -0700231static int call_helper(void *data)
232{
233 /* Worker thread started blocking khelper thread. */
234 kmod_thread_locker = current;
235 return ____call_usermodehelper(data);
236}
237
Boaz Harroshae3cef72012-05-31 16:26:14 -0700238static void call_usermodehelper_freeinfo(struct subprocess_info *info)
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700239{
240 if (info->cleanup)
Neil Hormana06a4dc2010-05-26 14:42:58 -0700241 (*info->cleanup)(info);
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700242 kfree(info);
243}
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700244
Oleg Nesterovb3449922012-03-23 15:02:47 -0700245static void umh_complete(struct subprocess_info *sub_info)
246{
Oleg Nesterovd0bd5872012-03-23 15:02:47 -0700247 struct completion *comp = xchg(&sub_info->complete, NULL);
248 /*
249 * See call_usermodehelper_exec(). If xchg() returns NULL
250 * we own sub_info, the UMH_KILLABLE caller has gone away.
251 */
252 if (comp)
253 complete(comp);
254 else
255 call_usermodehelper_freeinfo(sub_info);
Oleg Nesterovb3449922012-03-23 15:02:47 -0700256}
257
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258/* Keventd can't block, but this (a child) can. */
259static int wait_for_helper(void *data)
260{
261 struct subprocess_info *sub_info = data;
262 pid_t pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263
Oleg Nesterov7d642242010-05-26 14:43:03 -0700264 /* If SIGCLD is ignored sys_wait4 won't populate the status. */
265 spin_lock_irq(&current->sighand->siglock);
266 current->sighand->action[SIGCHLD-1].sa.sa_handler = SIG_DFL;
267 spin_unlock_irq(&current->sighand->siglock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268
269 pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
270 if (pid < 0) {
271 sub_info->retval = pid;
272 } else {
Oleg Nesterov7d642242010-05-26 14:43:03 -0700273 int ret = -ECHILD;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 /*
275 * Normally it is bogus to call wait4() from in-kernel because
276 * wait4() wants to write the exit code to a userspace address.
277 * But wait_for_helper() always runs as keventd, and put_user()
278 * to a kernel address works OK for kernel threads, due to their
279 * having an mm_segment_t which spans the entire address space.
280 *
281 * Thus the __user pointer cast is valid here.
282 */
Björn Steinbrink111dbe02006-09-29 02:00:46 -0700283 sys_wait4(pid, (int __user *)&ret, 0, NULL);
284
285 /*
286 * If ret is 0, either ____call_usermodehelper failed and the
287 * real error code is already in sub_info->retval or
288 * sub_info->retval is 0 anyway, so don't mess with it then.
289 */
290 if (ret)
291 sub_info->retval = ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 }
293
Oleg Nesterovb3449922012-03-23 15:02:47 -0700294 umh_complete(sub_info);
Al Virofb455502012-10-10 20:09:44 -0400295 do_exit(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296}
297
298/* This is run by khelper thread */
David Howells65f27f32006-11-22 14:55:48 +0000299static void __call_usermodehelper(struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300{
David Howells65f27f32006-11-22 14:55:48 +0000301 struct subprocess_info *sub_info =
302 container_of(work, struct subprocess_info, work);
Oleg Nesterov9d944ef2012-03-23 15:02:48 -0700303 int wait = sub_info->wait & ~UMH_KILLABLE;
Oleg Nesterovd47419c2010-05-26 14:43:04 -0700304 pid_t pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
306 /* CLONE_VFORK: wait until the usermode helper has execve'd
307 * successfully We need the data structures to stay around
308 * until that is done. */
Oleg Nesterovd47419c2010-05-26 14:43:04 -0700309 if (wait == UMH_WAIT_PROC)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 pid = kernel_thread(wait_for_helper, sub_info,
311 CLONE_FS | CLONE_FILES | SIGCHLD);
Tetsuo Handa0f207842012-07-30 14:42:20 -0700312 else {
313 pid = kernel_thread(call_helper, sub_info,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 CLONE_VFORK | SIGCHLD);
Tetsuo Handa0f207842012-07-30 14:42:20 -0700315 /* Worker thread stopped blocking khelper thread. */
316 kmod_thread_locker = NULL;
317 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318
Jeremy Fitzhardinge86313c42007-07-17 18:37:03 -0700319 switch (wait) {
320 case UMH_NO_WAIT:
Oleg Nesterovd47419c2010-05-26 14:43:04 -0700321 call_usermodehelper_freeinfo(sub_info);
Jeremy Fitzhardinge86313c42007-07-17 18:37:03 -0700322 break;
Andi Kleena98f0dd2007-02-13 13:26:23 +0100323
Jeremy Fitzhardinge86313c42007-07-17 18:37:03 -0700324 case UMH_WAIT_PROC:
325 if (pid > 0)
326 break;
Jeremy Fitzhardinge86313c42007-07-17 18:37:03 -0700327 /* FALLTHROUGH */
Jeremy Fitzhardinge86313c42007-07-17 18:37:03 -0700328 case UMH_WAIT_EXEC:
Oleg Nesterov04b1c382010-05-26 14:43:05 -0700329 if (pid < 0)
330 sub_info->retval = pid;
Oleg Nesterovb3449922012-03-23 15:02:47 -0700331 umh_complete(sub_info);
Jeremy Fitzhardinge86313c42007-07-17 18:37:03 -0700332 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333}
334
Rafael J. Wysockiccd4b652007-07-19 01:47:37 -0700335/*
336 * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
337 * (used for preventing user land processes from being created after the user
338 * land has been frozen during a system-wide hibernation or suspend operation).
Srivatsa S. Bhatb298d282011-12-09 23:36:36 +0100339 * Should always be manipulated under umhelper_sem acquired for write.
Rafael J. Wysockiccd4b652007-07-19 01:47:37 -0700340 */
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200341static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
Rafael J. Wysockiccd4b652007-07-19 01:47:37 -0700342
343/* Number of helpers running */
344static atomic_t running_helpers = ATOMIC_INIT(0);
345
346/*
Srivatsa S. Bhat53074272011-11-15 21:59:21 +0100347 * Wait queue head used by usermodehelper_disable() to wait for all running
Rafael J. Wysockiccd4b652007-07-19 01:47:37 -0700348 * helpers to finish.
349 */
350static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
351
352/*
Rafael J. Wysocki9b78c1d2012-03-28 23:30:02 +0200353 * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
354 * to become 'false'.
355 */
356static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
357
358/*
Rafael J. Wysockiccd4b652007-07-19 01:47:37 -0700359 * Time to wait for running_helpers to become zero before the setting of
Srivatsa S. Bhat53074272011-11-15 21:59:21 +0100360 * usermodehelper_disabled in usermodehelper_disable() fails
Rafael J. Wysockiccd4b652007-07-19 01:47:37 -0700361 */
362#define RUNNING_HELPERS_TIMEOUT (5 * HZ)
363
Rafael J. Wysockife2e39d82012-03-28 23:29:45 +0200364int usermodehelper_read_trylock(void)
Srivatsa S. Bhatb298d282011-12-09 23:36:36 +0100365{
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200366 DEFINE_WAIT(wait);
Rafael J. Wysockife2e39d82012-03-28 23:29:45 +0200367 int ret = 0;
Srivatsa S. Bhatb298d282011-12-09 23:36:36 +0100368
Rafael J. Wysockife2e39d82012-03-28 23:29:45 +0200369 down_read(&umhelper_sem);
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200370 for (;;) {
371 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
372 TASK_INTERRUPTIBLE);
373 if (!usermodehelper_disabled)
374 break;
375
376 if (usermodehelper_disabled == UMH_DISABLED)
377 ret = -EAGAIN;
378
Rafael J. Wysockife2e39d82012-03-28 23:29:45 +0200379 up_read(&umhelper_sem);
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200380
381 if (ret)
382 break;
383
384 schedule();
385 try_to_freeze();
386
387 down_read(&umhelper_sem);
Rafael J. Wysockife2e39d82012-03-28 23:29:45 +0200388 }
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200389 finish_wait(&usermodehelper_disabled_waitq, &wait);
Rafael J. Wysockife2e39d82012-03-28 23:29:45 +0200390 return ret;
391}
392EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
393
Rafael J. Wysocki9b78c1d2012-03-28 23:30:02 +0200394long usermodehelper_read_lock_wait(long timeout)
395{
396 DEFINE_WAIT(wait);
397
398 if (timeout < 0)
399 return -EINVAL;
400
401 down_read(&umhelper_sem);
402 for (;;) {
403 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
404 TASK_UNINTERRUPTIBLE);
405 if (!usermodehelper_disabled)
406 break;
407
408 up_read(&umhelper_sem);
409
410 timeout = schedule_timeout(timeout);
411 if (!timeout)
412 break;
413
414 down_read(&umhelper_sem);
415 }
416 finish_wait(&usermodehelper_disabled_waitq, &wait);
417 return timeout;
418}
419EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
420
Rafael J. Wysockife2e39d82012-03-28 23:29:45 +0200421void usermodehelper_read_unlock(void)
Srivatsa S. Bhatb298d282011-12-09 23:36:36 +0100422{
423 up_read(&umhelper_sem);
424}
Rafael J. Wysockife2e39d82012-03-28 23:29:45 +0200425EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
Srivatsa S. Bhatb298d282011-12-09 23:36:36 +0100426
Rafael J. Wysocki1bfcf132008-10-15 22:01:21 -0700427/**
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200428 * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
Randy Dunlap9b3c98c2012-05-31 16:26:15 -0700429 * @depth: New value to assign to usermodehelper_disabled.
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200430 *
431 * Change the value of usermodehelper_disabled (under umhelper_sem locked for
432 * writing) and wakeup tasks waiting for it to change.
Rafael J. Wysocki9b78c1d2012-03-28 23:30:02 +0200433 */
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200434void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
Rafael J. Wysocki9b78c1d2012-03-28 23:30:02 +0200435{
436 down_write(&umhelper_sem);
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200437 usermodehelper_disabled = depth;
Rafael J. Wysocki9b78c1d2012-03-28 23:30:02 +0200438 wake_up(&usermodehelper_disabled_waitq);
439 up_write(&umhelper_sem);
440}
441
442/**
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200443 * __usermodehelper_disable - Prevent new helpers from being started.
444 * @depth: New value to assign to usermodehelper_disabled.
445 *
446 * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
Rafael J. Wysocki1bfcf132008-10-15 22:01:21 -0700447 */
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200448int __usermodehelper_disable(enum umh_disable_depth depth)
Rafael J. Wysocki8cdd4932007-07-19 01:47:36 -0700449{
Rafael J. Wysockiccd4b652007-07-19 01:47:37 -0700450 long retval;
451
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200452 if (!depth)
453 return -EINVAL;
454
Srivatsa S. Bhatb298d282011-12-09 23:36:36 +0100455 down_write(&umhelper_sem);
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200456 usermodehelper_disabled = depth;
Srivatsa S. Bhatb298d282011-12-09 23:36:36 +0100457 up_write(&umhelper_sem);
458
Rafael J. Wysocki1bfcf132008-10-15 22:01:21 -0700459 /*
460 * From now on call_usermodehelper_exec() won't start any new
461 * helpers, so it is sufficient if running_helpers turns out to
462 * be zero at one point (it may be increased later, but that
463 * doesn't matter).
464 */
465 retval = wait_event_timeout(running_helpers_waitq,
Rafael J. Wysockiccd4b652007-07-19 01:47:37 -0700466 atomic_read(&running_helpers) == 0,
467 RUNNING_HELPERS_TIMEOUT);
Rafael J. Wysocki1bfcf132008-10-15 22:01:21 -0700468 if (retval)
469 return 0;
Rafael J. Wysocki8cdd4932007-07-19 01:47:36 -0700470
Rafael J. Wysocki247bc032012-03-28 23:30:28 +0200471 __usermodehelper_set_disable_depth(UMH_ENABLED);
Rafael J. Wysocki1bfcf132008-10-15 22:01:21 -0700472 return -EAGAIN;
473}
474
Rafael J. Wysockiccd4b652007-07-19 01:47:37 -0700475static void helper_lock(void)
476{
477 atomic_inc(&running_helpers);
478 smp_mb__after_atomic_inc();
479}
480
481static void helper_unlock(void)
482{
483 if (atomic_dec_and_test(&running_helpers))
484 wake_up(&running_helpers_waitq);
485}
Rafael J. Wysockiccd4b652007-07-19 01:47:37 -0700486
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487/**
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700488 * call_usermodehelper_setup - prepare to call a usermode helper
Randy Dunlap61df47c2007-07-26 10:40:56 -0700489 * @path: path to usermode executable
490 * @argv: arg vector for process
491 * @envp: environment for process
KOSAKI Motohiroac331d12008-07-25 01:45:38 -0700492 * @gfp_mask: gfp mask for memory allocation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 *
Randy Dunlap61df47c2007-07-26 10:40:56 -0700494 * Returns either %NULL on allocation failure, or a subprocess_info
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700495 * structure. This should be passed to call_usermodehelper_exec to
496 * exec the process and free the structure.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497 */
Boaz Harrosh785042f2012-05-31 16:26:15 -0700498static
KOSAKI Motohiroac331d12008-07-25 01:45:38 -0700499struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
500 char **envp, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501{
Andi Kleena98f0dd2007-02-13 13:26:23 +0100502 struct subprocess_info *sub_info;
KOSAKI Motohiroac331d12008-07-25 01:45:38 -0700503 sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
Andi Kleena98f0dd2007-02-13 13:26:23 +0100504 if (!sub_info)
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700505 goto out;
Andi Kleena98f0dd2007-02-13 13:26:23 +0100506
507 INIT_WORK(&sub_info->work, __call_usermodehelper);
Andi Kleena98f0dd2007-02-13 13:26:23 +0100508 sub_info->path = path;
509 sub_info->argv = argv;
510 sub_info->envp = envp;
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700511 out:
512 return sub_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700515/**
Neil Hormana06a4dc2010-05-26 14:42:58 -0700516 * call_usermodehelper_setfns - set a cleanup/init function
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700517 * @info: a subprocess_info returned by call_usermodehelper_setup
518 * @cleanup: a cleanup function
Neil Hormana06a4dc2010-05-26 14:42:58 -0700519 * @init: an init function
520 * @data: arbitrary context sensitive data
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700521 *
Neil Hormana06a4dc2010-05-26 14:42:58 -0700522 * The init function is used to customize the helper process prior to
523 * exec. A non-zero return code causes the process to error out, exit,
524 * and return the failure to the calling process
525 *
526 * The cleanup function is just before ethe subprocess_info is about to
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700527 * be freed. This can be used for freeing the argv and envp. The
528 * Function must be runnable in either a process context or the
529 * context in which call_usermodehelper_exec is called.
530 */
Boaz Harrosh785042f2012-05-31 16:26:15 -0700531static
Neil Hormana06a4dc2010-05-26 14:42:58 -0700532void call_usermodehelper_setfns(struct subprocess_info *info,
David Howells87966992011-06-17 11:25:59 +0100533 int (*init)(struct subprocess_info *info, struct cred *new),
Neil Hormana06a4dc2010-05-26 14:42:58 -0700534 void (*cleanup)(struct subprocess_info *info),
535 void *data)
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700536{
537 info->cleanup = cleanup;
Neil Hormana06a4dc2010-05-26 14:42:58 -0700538 info->init = init;
539 info->data = data;
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700540}
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700541
542/**
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700543 * call_usermodehelper_exec - start a usermode application
544 * @sub_info: information about the subprocessa
545 * @wait: wait for the application to finish and return status.
546 * when -1 don't wait at all, but you get no useful error back when
547 * the program couldn't be exec'ed. This makes it safe to call
548 * from interrupt context.
549 *
550 * Runs a user-space application. The application is started
551 * asynchronously if wait is not set, and runs as a child of keventd.
552 * (ie. it runs with full root capabilities).
553 */
Boaz Harrosh785042f2012-05-31 16:26:15 -0700554static
Oleg Nesterov9d944ef2012-03-23 15:02:48 -0700555int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700556{
557 DECLARE_COMPLETION_ONSTACK(done);
Nigel Cunningham78468032008-01-17 15:21:21 -0800558 int retval = 0;
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700559
Rafael J. Wysockiccd4b652007-07-19 01:47:37 -0700560 helper_lock();
Nigel Cunningham78468032008-01-17 15:21:21 -0800561 if (sub_info->path[0] == '\0')
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700562 goto out;
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700563
Rafael J. Wysocki8cdd4932007-07-19 01:47:36 -0700564 if (!khelper_wq || usermodehelper_disabled) {
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700565 retval = -EBUSY;
566 goto out;
567 }
Tetsuo Handa0f207842012-07-30 14:42:20 -0700568 /*
569 * Worker thread must not wait for khelper thread at below
570 * wait_for_completion() if the thread was created with CLONE_VFORK
571 * flag, for khelper thread is already waiting for the thread at
572 * wait_for_completion() in do_fork().
573 */
574 if (wait != UMH_NO_WAIT && current == kmod_thread_locker) {
575 retval = -EBUSY;
576 goto out;
577 }
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700578
579 sub_info->complete = &done;
580 sub_info->wait = wait;
581
582 queue_work(khelper_wq, &sub_info->work);
Nigel Cunningham78468032008-01-17 15:21:21 -0800583 if (wait == UMH_NO_WAIT) /* task has freed sub_info */
584 goto unlock;
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700585
Oleg Nesterovd0bd5872012-03-23 15:02:47 -0700586 if (wait & UMH_KILLABLE) {
587 retval = wait_for_completion_killable(&done);
588 if (!retval)
589 goto wait_done;
590
591 /* umh_complete() will see NULL and free sub_info */
592 if (xchg(&sub_info->complete, NULL))
593 goto unlock;
594 /* fallthrough, umh_complete() was already called */
595 }
596
597 wait_for_completion(&done);
598wait_done:
599 retval = sub_info->retval;
Nigel Cunningham78468032008-01-17 15:21:21 -0800600out:
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700601 call_usermodehelper_freeinfo(sub_info);
Nigel Cunningham78468032008-01-17 15:21:21 -0800602unlock:
Rafael J. Wysockiccd4b652007-07-19 01:47:37 -0700603 helper_unlock();
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700604 return retval;
605}
Boaz Harrosh785042f2012-05-31 16:26:15 -0700606
Andrew Morton79c743d2012-07-30 14:42:17 -0700607/*
608 * call_usermodehelper_fns() will not run the caller-provided cleanup function
609 * if a memory allocation failure is experienced. So the caller might need to
610 * check the call_usermodehelper_fns() return value: if it is -ENOMEM, perform
611 * the necessaary cleanup within the caller.
612 */
Boaz Harrosh785042f2012-05-31 16:26:15 -0700613int call_usermodehelper_fns(
614 char *path, char **argv, char **envp, int wait,
615 int (*init)(struct subprocess_info *info, struct cred *new),
616 void (*cleanup)(struct subprocess_info *), void *data)
617{
618 struct subprocess_info *info;
619 gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
620
621 info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
622
623 if (info == NULL)
624 return -ENOMEM;
625
626 call_usermodehelper_setfns(info, init, cleanup, data);
627
628 return call_usermodehelper_exec(info, wait);
629}
630EXPORT_SYMBOL(call_usermodehelper_fns);
Jeremy Fitzhardinge0ab4dc92007-07-17 18:37:02 -0700631
Eric Paris17f60a72011-04-01 17:07:50 -0400632static int proc_cap_handler(struct ctl_table *table, int write,
633 void __user *buffer, size_t *lenp, loff_t *ppos)
634{
635 struct ctl_table t;
636 unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
637 kernel_cap_t new_cap;
638 int err, i;
639
640 if (write && (!capable(CAP_SETPCAP) ||
641 !capable(CAP_SYS_MODULE)))
642 return -EPERM;
643
644 /*
645 * convert from the global kernel_cap_t to the ulong array to print to
646 * userspace if this is a read.
647 */
648 spin_lock(&umh_sysctl_lock);
649 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) {
650 if (table->data == CAP_BSET)
651 cap_array[i] = usermodehelper_bset.cap[i];
652 else if (table->data == CAP_PI)
653 cap_array[i] = usermodehelper_inheritable.cap[i];
654 else
655 BUG();
656 }
657 spin_unlock(&umh_sysctl_lock);
658
659 t = *table;
660 t.data = &cap_array;
661
662 /*
663 * actually read or write and array of ulongs from userspace. Remember
664 * these are least significant 32 bits first
665 */
666 err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
667 if (err < 0)
668 return err;
669
670 /*
671 * convert from the sysctl array of ulongs to the kernel_cap_t
672 * internal representation
673 */
674 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
675 new_cap.cap[i] = cap_array[i];
676
677 /*
678 * Drop everything not in the new_cap (but don't add things)
679 */
680 spin_lock(&umh_sysctl_lock);
681 if (write) {
682 if (table->data == CAP_BSET)
683 usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
684 if (table->data == CAP_PI)
685 usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
686 }
687 spin_unlock(&umh_sysctl_lock);
688
689 return 0;
690}
691
692struct ctl_table usermodehelper_table[] = {
693 {
694 .procname = "bset",
695 .data = CAP_BSET,
696 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
697 .mode = 0600,
698 .proc_handler = proc_cap_handler,
699 },
700 {
701 .procname = "inheritable",
702 .data = CAP_PI,
703 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
704 .mode = 0600,
705 .proc_handler = proc_cap_handler,
706 },
707 { }
708};
709
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710void __init usermodehelper_init(void)
711{
712 khelper_wq = create_singlethread_workqueue("khelper");
713 BUG_ON(!khelper_wq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714}