[GitHub/LineageOS/android_kernel_motorola_exynos9610.git] / kernel / kmod.c

/*
	kmod, the new module loader (replaces kerneld)
	Kirk Petersen

	Reorganized not to be a daemon by Adam Richter, with guidance
	from Greg Zornetzer.

	Modified to avoid chroot and file sharing problems.
	Mikael Pettersson

	Limit the concurrent number of kmod modprobes to catch loops from
	"modprobe needs a service that is in a module".
	Keith Owens <kaos@ocs.com.au> December 1999

	Unblock all signals when we exec a usermode process.
	Shuu Yamaguchi <shuu@wondernetworkresources.com> December 2000

	call_usermodehelper wait flag, and remove exec_usermodehelper.
	Rusty Russell <rusty@rustcorp.com.au>  Jan 2003
*/
#define __KERNEL_SYSCALLS__

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/syscalls.h>
#include <linux/unistd.h>
#include <linux/kmod.h>
#include <linux/smp_lock.h>
#include <linux/slab.h>
#include <linux/namespace.h>
#include <linux/completion.h>
#include <linux/file.h>
#include <linux/workqueue.h>
#include <linux/security.h>
#include <linux/mount.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <asm/uaccess.h>

extern int max_threads;

static struct workqueue_struct *khelper_wq;

#ifdef CONFIG_KMOD

/*
	modprobe_path is set via /proc/sys.
*/
char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";

/**
 * request_module - try to load a kernel module
 * @fmt:     printf style format string for the name of the module
 * @varargs: arguements as specified in the format string
 *
 * Load a module using the user mode module loader. The function returns
 * zero on success or a negative errno code on failure. Note that a
 * successful module load does not mean the module did not then unload
 * and exit on an error of its own. Callers must check that the service
 * they requested is now available not blindly invoke it.
 *
 * If module auto-loading support is disabled then this function
 * becomes a no-operation.
 */
int request_module(const char *fmt, ...)
{
	va_list args;
	char module_name[MODULE_NAME_LEN];
	unsigned int max_modprobes;
	int ret;
	char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
	static char *envp[] = { "HOME=/",
				"TERM=linux",
				"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
				NULL };
	static atomic_t kmod_concurrent = ATOMIC_INIT(0);
#define MAX_KMOD_CONCURRENT 50	/* Completely arbitrary value - KAO */
	static int kmod_loop_msg;

	va_start(args, fmt);
	ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
	va_end(args);
	if (ret >= MODULE_NAME_LEN)
		return -ENAMETOOLONG;

	/* If modprobe needs a service that is in a module, we get a recursive
	 * loop.  Limit the number of running kmod threads to max_threads/2 or
	 * MAX_KMOD_CONCURRENT, whichever is the smaller.  A cleaner method
	 * would be to run the parents of this process, counting how many times
	 * kmod was invoked.  That would mean accessing the internals of the
	 * process tables to get the command line, proc_pid_cmdline is static
	 * and it is not worth changing the proc code just to handle this case. 
	 * KAO.
	 *
	 * "trace the ppid" is simple, but will fail if someone's
	 * parent exits.  I think this is as good as it gets. --RR
	 */
	max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
	atomic_inc(&kmod_concurrent);
	if (atomic_read(&kmod_concurrent) > max_modprobes) {
		/* We may be blaming an innocent here, but unlikely */
		if (kmod_loop_msg++ < 5)
			printk(KERN_ERR
			       "request_module: runaway loop modprobe %s\n",
			       module_name);
		atomic_dec(&kmod_concurrent);
		return -ENOMEM;
	}

	ret = call_usermodehelper(modprobe_path, argv, envp, 1);
	atomic_dec(&kmod_concurrent);
	return ret;
}
EXPORT_SYMBOL(request_module);
#endif /* CONFIG_KMOD */

struct subprocess_info {
	struct completion *complete;
	char *path;
	char **argv;
	char **envp;
	struct key *ring;
	int wait;
	int retval;
	struct file *stdin;
};

/*
 * This is the task which runs the usermode application
 */
static int ____call_usermodehelper(void *data)
{
	struct subprocess_info *sub_info = data;
	struct key *new_session, *old_session;
	int retval;

	/* Unblock all signals and set the session keyring. */
	new_session = key_get(sub_info->ring);
	flush_signals(current);
	spin_lock_irq(&current->sighand->siglock);
	old_session = __install_session_keyring(current, new_session);
	flush_signal_handlers(current, 1);
	sigemptyset(&current->blocked);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	key_put(old_session);

	/* Install input pipe when needed */
	if (sub_info->stdin) {
		struct files_struct *f = current->files;
		struct fdtable *fdt;
		/* no races because files should be private here */
		sys_close(0);
		fd_install(0, sub_info->stdin);
		spin_lock(&f->file_lock);
		fdt = files_fdtable(f);
		FD_SET(0, fdt->open_fds);
		FD_CLR(0, fdt->close_on_exec);
		spin_unlock(&f->file_lock);
	}

	/* We can run anywhere, unlike our parent keventd(). */
	set_cpus_allowed(current, CPU_MASK_ALL);

	retval = -EPERM;
	if (current->fs->root)
		retval = execve(sub_info->path, sub_info->argv, sub_info->envp);

	/* Exec failed? */
	sub_info->retval = retval;
	do_exit(0);
}

/* Keventd can't block, but this (a child) can. */
static int wait_for_helper(void *data)
{
	struct subprocess_info *sub_info = data;
	pid_t pid;
	struct k_sigaction sa;

	/* Install a handler: if SIGCLD isn't handled sys_wait4 won't
	 * populate the status, but will return -ECHILD. */
	sa.sa.sa_handler = SIG_IGN;
	sa.sa.sa_flags = 0;
	siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
	do_sigaction(SIGCHLD, &sa, NULL);
	allow_signal(SIGCHLD);

	pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
	if (pid < 0) {
		sub_info->retval = pid;
	} else {
		int ret;

		/*
		 * Normally it is bogus to call wait4() from in-kernel because
		 * wait4() wants to write the exit code to a userspace address.
		 * But wait_for_helper() always runs as keventd, and put_user()
		 * to a kernel address works OK for kernel threads, due to their
		 * having an mm_segment_t which spans the entire address space.
		 *
		 * Thus the __user pointer cast is valid here.
		 */
		sys_wait4(pid, (int __user *)&ret, 0, NULL);

		/*
		 * If ret is 0, either ____call_usermodehelper failed and the
		 * real error code is already in sub_info->retval or
		 * sub_info->retval is 0 anyway, so don't mess with it then.
		 */
		if (ret)
			sub_info->retval = ret;
	}

	complete(sub_info->complete);
	return 0;
}

/* This is run by khelper thread  */
static void __call_usermodehelper(void *data)
{
	struct subprocess_info *sub_info = data;
	pid_t pid;
	int wait = sub_info->wait;

	/* CLONE_VFORK: wait until the usermode helper has execve'd
	 * successfully We need the data structures to stay around
	 * until that is done.  */
	if (wait)
		pid = kernel_thread(wait_for_helper, sub_info,
				    CLONE_FS | CLONE_FILES | SIGCHLD);
	else
		pid = kernel_thread(____call_usermodehelper, sub_info,
				    CLONE_VFORK | SIGCHLD);

	if (pid < 0) {
		sub_info->retval = pid;
		complete(sub_info->complete);
	} else if (!wait)
		complete(sub_info->complete);
}

/**
 * call_usermodehelper_keys - start a usermode application
 * @path: pathname for the application
 * @argv: null-terminated argument list
 * @envp: null-terminated environment list
 * @session_keyring: session keyring for process (NULL for an empty keyring)
 * @wait: wait for the application to finish and return status.
 *
 * Runs a user-space application.  The application is started
 * asynchronously if wait is not set, and runs as a child of keventd.
 * (ie. it runs with full root capabilities).
 *
 * Must be called from process context.  Returns a negative error code
 * if program was not execed successfully, or 0.
 */
int call_usermodehelper_keys(char *path, char **argv, char **envp,
			     struct key *session_keyring, int wait)
{
	DECLARE_COMPLETION_ONSTACK(done);
	struct subprocess_info sub_info = {
		.complete	= &done,
		.path		= path,
		.argv		= argv,
		.envp		= envp,
		.ring		= session_keyring,
		.wait		= wait,
		.retval		= 0,
	};
	DECLARE_WORK(work, __call_usermodehelper, &sub_info);

	if (!khelper_wq)
		return -EBUSY;

	if (path[0] == '\0')
		return 0;

	queue_work(khelper_wq, &work);
	wait_for_completion(&done);
	return sub_info.retval;
}
EXPORT_SYMBOL(call_usermodehelper_keys);

int call_usermodehelper_pipe(char *path, char **argv, char **envp,
			     struct file **filp)
{
	DECLARE_COMPLETION(done);
	struct subprocess_info sub_info = {
		.complete	= &done,
		.path		= path,
		.argv		= argv,
		.envp		= envp,
		.retval		= 0,
	};
	struct file *f;
	DECLARE_WORK(work, __call_usermodehelper, &sub_info);

	if (!khelper_wq)
		return -EBUSY;

	if (path[0] == '\0')
		return 0;

	f = create_write_pipe();
	if (!f)
		return -ENOMEM;
	*filp = f;

	f = create_read_pipe(f);
	if (!f) {
		free_write_pipe(*filp);
		return -ENOMEM;
	}
	sub_info.stdin = f;

	queue_work(khelper_wq, &work);
	wait_for_completion(&done);
	return sub_info.retval;
}
EXPORT_SYMBOL(call_usermodehelper_pipe);

void __init usermodehelper_init(void)
{
	khelper_wq = create_singlethread_workqueue("khelper");
	BUG_ON(!khelper_wq);
}
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	*/
	21	#define __KERNEL_SYSCALLS__
	22
1da177e4 LT	23	#include <linux/module.h>
	24	#include <linux/sched.h>
	25	#include <linux/syscalls.h>
	26	#include <linux/unistd.h>
	27	#include <linux/kmod.h>
	28	#include <linux/smp_lock.h>
	29	#include <linux/slab.h>
	30	#include <linux/namespace.h>
	31	#include <linux/completion.h>
	32	#include <linux/file.h>
	33	#include <linux/workqueue.h>
	34	#include <linux/security.h>
	35	#include <linux/mount.h>
	36	#include <linux/kernel.h>
	37	#include <linux/init.h>
	38	#include <asm/uaccess.h>
	39
	40	extern int max_threads;
	41
	42	static struct workqueue_struct *khelper_wq;
	43
	44	#ifdef CONFIG_KMOD
	45
	46	/*
	47	modprobe_path is set via /proc/sys.
	48	*/
	49	char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
	50
	51	/**
	52	* request_module - try to load a kernel module
	53	* @fmt: printf style format string for the name of the module
	54	* @varargs: arguements as specified in the format string
	55	*
	56	* Load a module using the user mode module loader. The function returns
	57	* zero on success or a negative errno code on failure. Note that a
	58	* successful module load does not mean the module did not then unload
	59	* and exit on an error of its own. Callers must check that the service
	60	* they requested is now available not blindly invoke it.
	61	*
	62	* If module auto-loading support is disabled then this function
	63	* becomes a no-operation.
	64	*/
	65	int request_module(const char *fmt, ...)
	66	{
	67	va_list args;
	68	char module_name[MODULE_NAME_LEN];
	69	unsigned int max_modprobes;
	70	int ret;
	71	char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
	72	static char *envp[] = { "HOME=/",
	73	"TERM=linux",
	74	"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
	75	NULL };
	76	static atomic_t kmod_concurrent = ATOMIC_INIT(0);
	77	#define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */
	78	static int kmod_loop_msg;
	79
	80	va_start(args, fmt);
	81	ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
	82	va_end(args);
	83	if (ret >= MODULE_NAME_LEN)
	84	return -ENAMETOOLONG;
	85
	86	/* If modprobe needs a service that is in a module, we get a recursive
87	* loop. Limit the number of running kmod threads to max_threads/2 or
88	* MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method
89	* would be to run the parents of this process, counting how many times
90	* kmod was invoked. That would mean accessing the internals of the
91	* process tables to get the command line, proc_pid_cmdline is static
92	* and it is not worth changing the proc code just to handle this case.
93	* KAO.
94	*
95	* "trace the ppid" is simple, but will fail if someone's
96	* parent exits. I think this is as good as it gets. --RR
97	*/
98	max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
99	atomic_inc(&kmod_concurrent);
100	if (atomic_read(&kmod_concurrent) > max_modprobes) {
101	/* We may be blaming an innocent here, but unlikely */
102	if (kmod_loop_msg++ < 5)
103	printk(KERN_ERR
104	"request_module: runaway loop modprobe %s\n",
105	module_name);
106	atomic_dec(&kmod_concurrent);
107	return -ENOMEM;
108	}
109
110	ret = call_usermodehelper(modprobe_path, argv, envp, 1);
111	atomic_dec(&kmod_concurrent);
112	return ret;
113	}
114	EXPORT_SYMBOL(request_module);
115	#endif /* CONFIG_KMOD */
116
117	struct subprocess_info {
118	struct completion *complete;
119	char *path;
120	char **argv;
121	char **envp;
7888e7ff	122	struct key *ring;
1da177e4 LT	123	int wait;
1da177e4 LT	124	int retval;
e239ca54	125	struct file *stdin;
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;
1da177e4 LT	136
7888e7ff	137	/* Unblock all signals and set the session keyring. */
20e1129a	138	new_session = key_get(sub_info->ring);
1da177e4 LT	139	flush_signals(current);
1da177e4 LT	140	spin_lock_irq(&current->sighand->siglock);
20e1129a	141	old_session = __install_session_keyring(current, new_session);
1da177e4 LT	142	flush_signal_handlers(current, 1);
	143	sigemptyset(&current->blocked);
	144	recalc_sigpending();
	145	spin_unlock_irq(&current->sighand->siglock);
	146
7888e7ff DH	147	key_put(old_session);
7888e7ff DH	148
e239ca54 AK	149	/* Install input pipe when needed */
	150	if (sub_info->stdin) {
	151	struct files_struct *f = current->files;
	152	struct fdtable *fdt;
	153	/* no races because files should be private here */
	154	sys_close(0);
	155	fd_install(0, sub_info->stdin);
	156	spin_lock(&f->file_lock);
	157	fdt = files_fdtable(f);
	158	FD_SET(0, fdt->open_fds);
	159	FD_CLR(0, fdt->close_on_exec);
	160	spin_unlock(&f->file_lock);
	161	}
	162
1da177e4 LT	163	/* We can run anywhere, unlike our parent keventd(). */
	164	set_cpus_allowed(current, CPU_MASK_ALL);
	165
	166	retval = -EPERM;
	167	if (current->fs->root)
e239ca54	168	retval = execve(sub_info->path, sub_info->argv, sub_info->envp);
1da177e4 LT	169
	170	/* Exec failed? */
	171	sub_info->retval = retval;
	172	do_exit(0);
	173	}
	174
	175	/* Keventd can't block, but this (a child) can. */
	176	static int wait_for_helper(void *data)
	177	{
	178	struct subprocess_info *sub_info = data;
	179	pid_t pid;
	180	struct k_sigaction sa;
	181
	182	/* Install a handler: if SIGCLD isn't handled sys_wait4 won't
	183	* populate the status, but will return -ECHILD. */
	184	sa.sa.sa_handler = SIG_IGN;
	185	sa.sa.sa_flags = 0;
	186	siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
8292d633	187	do_sigaction(SIGCHLD, &sa, NULL);
1da177e4 LT	188	allow_signal(SIGCHLD);
	189
	190	pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
	191	if (pid < 0) {
	192	sub_info->retval = pid;
	193	} else {
111dbe0c BS	194	int ret;
111dbe0c BS	195
1da177e4 LT	196	/*
	197	* Normally it is bogus to call wait4() from in-kernel because
	198	* wait4() wants to write the exit code to a userspace address.
	199	* But wait_for_helper() always runs as keventd, and put_user()
	200	* to a kernel address works OK for kernel threads, due to their
	201	* having an mm_segment_t which spans the entire address space.
	202	*
	203	* Thus the __user pointer cast is valid here.
	204	*/
111dbe0c BS	205	sys_wait4(pid, (int __user *)&ret, 0, NULL);
	206
	207	/*
	208	* If ret is 0, either ____call_usermodehelper failed and the
	209	* real error code is already in sub_info->retval or
	210	* sub_info->retval is 0 anyway, so don't mess with it then.
	211	*/
	212	if (ret)
	213	sub_info->retval = ret;
1da177e4 LT	214	}
	215
	216	complete(sub_info->complete);
	217	return 0;
	218	}
	219
	220	/* This is run by khelper thread */
	221	static void __call_usermodehelper(void *data)
	222	{
	223	struct subprocess_info *sub_info = data;
	224	pid_t pid;
e4b69aa2	225	int wait = sub_info->wait;
1da177e4 LT	226
	227	/* CLONE_VFORK: wait until the usermode helper has execve'd
	228	* successfully We need the data structures to stay around
	229	* until that is done. */
e4b69aa2	230	if (wait)
1da177e4 LT	231	pid = kernel_thread(wait_for_helper, sub_info,
	232	CLONE_FS \| CLONE_FILES \| SIGCHLD);
	233	else
	234	pid = kernel_thread(____call_usermodehelper, sub_info,
	235	CLONE_VFORK \| SIGCHLD);
	236
	237	if (pid < 0) {
	238	sub_info->retval = pid;
	239	complete(sub_info->complete);
e4b69aa2	240	} else if (!wait)
1da177e4 LT	241	complete(sub_info->complete);
	242	}
	243
	244	/**
7888e7ff	245	* call_usermodehelper_keys - start a usermode application
1da177e4 LT	246	* @path: pathname for the application
	247	* @argv: null-terminated argument list
	248	* @envp: null-terminated environment list
7888e7ff	249	* @session_keyring: session keyring for process (NULL for an empty keyring)
1da177e4 LT	250	* @wait: wait for the application to finish and return status.
	251	*
	252	* Runs a user-space application. The application is started
	253	* asynchronously if wait is not set, and runs as a child of keventd.
	254	* (ie. it runs with full root capabilities).
	255	*
	256	* Must be called from process context. Returns a negative error code
	257	* if program was not execed successfully, or 0.
	258	*/
7888e7ff DH	259	int call_usermodehelper_keys(char path, char argv, char *envp,
7888e7ff DH	260	struct key *session_keyring, int wait)
1da177e4	261	{
60be6b9a	262	DECLARE_COMPLETION_ONSTACK(done);
1da177e4 LT	263	struct subprocess_info sub_info = {
	264	.complete = &done,
	265	.path = path,
	266	.argv = argv,
	267	.envp = envp,
7888e7ff	268	.ring = session_keyring,
1da177e4 LT	269	.wait = wait,
	270	.retval = 0,
	271	};
	272	DECLARE_WORK(work, __call_usermodehelper, &sub_info);
	273
	274	if (!khelper_wq)
	275	return -EBUSY;
	276
	277	if (path[0] == '\0')
	278	return 0;
	279
	280	queue_work(khelper_wq, &work);
	281	wait_for_completion(&done);
	282	return sub_info.retval;
	283	}
7888e7ff	284	EXPORT_SYMBOL(call_usermodehelper_keys);
1da177e4	285
e239ca54 AK	286	int call_usermodehelper_pipe(char path, char argv, char *envp,
	287	struct file **filp)
	288	{
	289	DECLARE_COMPLETION(done);
	290	struct subprocess_info sub_info = {
	291	.complete = &done,
	292	.path = path,
	293	.argv = argv,
	294	.envp = envp,
	295	.retval = 0,
	296	};
	297	struct file *f;
	298	DECLARE_WORK(work, __call_usermodehelper, &sub_info);
	299
	300	if (!khelper_wq)
	301	return -EBUSY;
	302
	303	if (path[0] == '\0')
	304	return 0;
	305
	306	f = create_write_pipe();
	307	if (!f)
	308	return -ENOMEM;
	309	*filp = f;
	310
	311	f = create_read_pipe(f);
	312	if (!f) {
	313	free_write_pipe(*filp);
	314	return -ENOMEM;
	315	}
	316	sub_info.stdin = f;
	317
	318	queue_work(khelper_wq, &work);
	319	wait_for_completion(&done);
	320	return sub_info.retval;
	321	}
	322	EXPORT_SYMBOL(call_usermodehelper_pipe);
	323
1da177e4 LT	324	void __init usermodehelper_init(void)
	325	{
	326	khelper_wq = create_singlethread_workqueue("khelper");
	327	BUG_ON(!khelper_wq);
	328	}