[deliverable/linux.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
*/
#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/mnt_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 <linux/resource.h>
#include <asm/uaccess.h>

extern int delete_module(const char *name, unsigned int flags);

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";
struct module_kobject kmod_mk;

/**
 * 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;
	char modalias[16 + MODULE_NAME_LEN] = "MODALIAS=";
	char *uevent_envp[2] = {
		modalias,
		NULL
	};

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

	strcpy(&modalias[strlen("MODALIAS=")], module_name);
	kobject_uevent_env(&kmod_mk.kobj, KOBJ_CHANGE, uevent_envp);

	if (modprobe_path[0] == '\0')
		goto out;

	/* 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);
out:
	return ret;
}
EXPORT_SYMBOL(request_module);

static ssize_t store_mod_request(struct module_attribute *mattr,
				 struct module *mod,
			      const char *buffer, size_t count)
{
	char name[MODULE_NAME_LEN];
	int ret;

	if (count < 1 || count+1 > MODULE_NAME_LEN)
		return -EINVAL;
	memcpy(name, buffer, count);
	name[count] = '\0';
	if (name[count-1] == '\n')
		name[count-1] = '\0';

	ret = request_module(name);
	if (ret < 0)
		return ret;
	return count;
}

static struct module_attribute mod_request = {
	.attr = { .name = "mod_request", .mode = S_IWUSR, .owner = THIS_MODULE },
	.store = store_mod_request,
};

#ifdef CONFIG_MODULE_UNLOAD
static ssize_t store_mod_unload(struct module_attribute *mattr,
			    struct module *mod,
			    const char *buffer, size_t count)
{
	char name[MODULE_NAME_LEN];
	int ret;

	if (count < 1 || count+1 > MODULE_NAME_LEN)
		return -EINVAL;
	memcpy(name, buffer, count);
	name[count] = '\0';
	if (name[count-1] == '\n')
		name[count-1] = '\0';

	ret = delete_module(name, O_NONBLOCK);
	if (ret < 0)
		return ret;
	return count;
}

static struct module_attribute mod_unload = {
	.attr = { .name = "mod_unload", .mode = S_IWUSR, .owner = THIS_MODULE },
	.store = store_mod_unload,
};
#endif

static ssize_t show_mod_request_helper(struct module_attribute *mattr,
				       struct module *mod,
				       char *buffer)
{
	return sprintf(buffer, "%s\n", modprobe_path);
}

static ssize_t store_mod_request_helper(struct module_attribute *mattr,
					struct module *mod,
					const char *buffer, size_t count)
{
	if (count < 1 || count+1 > KMOD_PATH_LEN)
		return -EINVAL;
	memcpy(modprobe_path, buffer, count);
	modprobe_path[count] = '\0';
	if (modprobe_path[count-1] == '\n')
		modprobe_path[count-1] = '\0';
	return count;
}

static struct module_attribute mod_request_helper = {
	.attr = {
		.name = "mod_request_helper",
		.mode = S_IWUSR | S_IRUGO,
		.owner = THIS_MODULE
	},
	.show = show_mod_request_helper,
	.store = store_mod_request_helper,
};

void __init kmod_sysfs_init(void)
{
	int ret;

	kmod_mk.mod = THIS_MODULE;
	kobj_set_kset_s(&kmod_mk, module_subsys);
	kobject_set_name(&kmod_mk.kobj, "kmod");
	kobject_init(&kmod_mk.kobj);
	ret = kobject_add(&kmod_mk.kobj);
	if (ret < 0)
		goto out;

	ret = sysfs_create_file(&kmod_mk.kobj, &mod_request_helper.attr);
	ret = sysfs_create_file(&kmod_mk.kobj, &mod_request.attr);
#ifdef CONFIG_MODULE_UNLOAD
	ret = sysfs_create_file(&kmod_mk.kobj, &mod_unload.attr);
#endif

	kobject_uevent(&kmod_mk.kobj, KOBJ_ADD);
out:
	return;
}
#endif /* CONFIG_KMOD */

struct subprocess_info {
	struct work_struct work;
	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);

		/* and disallow core files too */
		current->signal->rlim[RLIMIT_CORE] = (struct rlimit){0, 0};
	}

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

	retval = -EPERM;
	if (current->fs->root)
		retval = kernel_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;
	}

	if (sub_info->wait < 0)
		kfree(sub_info);
	else
		complete(sub_info->complete);
	return 0;
}

/* This is run by khelper thread  */
static void __call_usermodehelper(struct work_struct *work)
{
	struct subprocess_info *sub_info =
		container_of(work, struct subprocess_info, work);
	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 (wait < 0)
		return;

	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.
 *        when -1 don't wait at all, but you get no useful error back when
 *        the program couldn't be exec'ed. This makes it safe to call
 *        from interrupt context.
 *
 * 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;
	int retval;

	if (!khelper_wq)
		return -EBUSY;

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

	sub_info = kzalloc(sizeof(struct subprocess_info),  GFP_ATOMIC);
	if (!sub_info)
		return -ENOMEM;

	INIT_WORK(&sub_info->work, __call_usermodehelper);
	sub_info->complete = &done;
	sub_info->path = path;
	sub_info->argv = argv;
	sub_info->envp = envp;
	sub_info->ring = session_keyring;
	sub_info->wait = wait;

	queue_work(khelper_wq, &sub_info->work);
	if (wait < 0) /* task has freed sub_info */
		return 0;
	wait_for_completion(&done);
	retval = sub_info->retval;
	kfree(sub_info);
	return 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 = {
		.work		= __WORK_INITIALIZER(sub_info.work,
						     __call_usermodehelper),
		.complete	= &done,
		.path		= path,
		.argv		= argv,
		.envp		= envp,
		.retval		= 0,
	};
	struct file *f;

	if (!khelper_wq)
		return -EBUSY;

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

	f = create_write_pipe();
	if (IS_ERR(f))
		return PTR_ERR(f);
	*filp = f;

	f = create_read_pipe(f);
	if (IS_ERR(f)) {
		free_write_pipe(*filp);
		return PTR_ERR(f);
	}
	sub_info.stdin = f;

	queue_work(khelper_wq, &sub_info.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	*/
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>
	26	#include <linux/smp_lock.h>
	27	#include <linux/slab.h>
6b3286ed	28	#include <linux/mnt_namespace.h>
1da177e4 LT	29	#include <linux/completion.h>
	30	#include <linux/file.h>
	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>
1da177e4 LT	37	#include <asm/uaccess.h>
1da177e4 LT	38
c353c3fb KS	39	extern int delete_module(const char *name, unsigned int flags);
c353c3fb KS	40
1da177e4 LT	41	extern int max_threads;
	42
	43	static struct workqueue_struct *khelper_wq;
	44
	45	#ifdef CONFIG_KMOD
	46
	47	/*
	48	modprobe_path is set via /proc/sys.
	49	*/
	50	char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
c353c3fb	51	struct module_kobject kmod_mk;
1da177e4 LT	52
	53	/**
	54	* request_module - try to load a kernel module
	55	* @fmt: printf style format string for the name of the module
	56	* @varargs: arguements as specified in the format string
	57	*
	58	* Load a module using the user mode module loader. The function returns
	59	* zero on success or a negative errno code on failure. Note that a
	60	* successful module load does not mean the module did not then unload
	61	* and exit on an error of its own. Callers must check that the service
	62	* they requested is now available not blindly invoke it.
	63	*
	64	* If module auto-loading support is disabled then this function
	65	* becomes a no-operation.
	66	*/
	67	int request_module(const char *fmt, ...)
	68	{
	69	va_list args;
	70	char module_name[MODULE_NAME_LEN];
	71	unsigned int max_modprobes;
	72	int ret;
	73	char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
	74	static char *envp[] = { "HOME=/",
	75	"TERM=linux",
	76	"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
	77	NULL };
	78	static atomic_t kmod_concurrent = ATOMIC_INIT(0);
	79	#define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */
	80	static int kmod_loop_msg;
c353c3fb KS	81	char modalias[16 + MODULE_NAME_LEN] = "MODALIAS=";
	82	char *uevent_envp[2] = {
	83	modalias,
	84	NULL
	85	};
1da177e4 LT	86
	87	va_start(args, fmt);
	88	ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
	89	va_end(args);
	90	if (ret >= MODULE_NAME_LEN)
	91	return -ENAMETOOLONG;
	92
c353c3fb KS	93	strcpy(&modalias[strlen("MODALIAS=")], module_name);
	94	kobject_uevent_env(&kmod_mk.kobj, KOBJ_CHANGE, uevent_envp);
	95
	96	if (modprobe_path[0] == '\0')
	97	goto out;
	98
1da177e4 LT	99	/* If modprobe needs a service that is in a module, we get a recursive
	100	* loop. Limit the number of running kmod threads to max_threads/2 or
	101	* MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method
	102	* would be to run the parents of this process, counting how many times
	103	* kmod was invoked. That would mean accessing the internals of the
	104	* process tables to get the command line, proc_pid_cmdline is static
	105	* and it is not worth changing the proc code just to handle this case.
	106	* KAO.
	107	*
	108	* "trace the ppid" is simple, but will fail if someone's
	109	* parent exits. I think this is as good as it gets. --RR
	110	*/
	111	max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
	112	atomic_inc(&kmod_concurrent);
	113	if (atomic_read(&kmod_concurrent) > max_modprobes) {
	114	/* We may be blaming an innocent here, but unlikely */
	115	if (kmod_loop_msg++ < 5)
	116	printk(KERN_ERR
	117	"request_module: runaway loop modprobe %s\n",
	118	module_name);
	119	atomic_dec(&kmod_concurrent);
	120	return -ENOMEM;
	121	}
	122
	123	ret = call_usermodehelper(modprobe_path, argv, envp, 1);
	124	atomic_dec(&kmod_concurrent);
c353c3fb	125	out:
1da177e4 LT	126	return ret;
	127	}
	128	EXPORT_SYMBOL(request_module);
c353c3fb KS	129
	130	static ssize_t store_mod_request(struct module_attribute *mattr,
	131	struct module *mod,
	132	const char *buffer, size_t count)
	133	{
	134	char name[MODULE_NAME_LEN];
	135	int ret;
	136
	137	if (count < 1 \|\| count+1 > MODULE_NAME_LEN)
	138	return -EINVAL;
	139	memcpy(name, buffer, count);
	140	name[count] = '\0';
	141	if (name[count-1] == '\n')
	142	name[count-1] = '\0';
	143
	144	ret = request_module(name);
	145	if (ret < 0)
	146	return ret;
	147	return count;
	148	}
	149
	150	static struct module_attribute mod_request = {
	151	.attr = { .name = "mod_request", .mode = S_IWUSR, .owner = THIS_MODULE },
	152	.store = store_mod_request,
	153	};
	154
	155	#ifdef CONFIG_MODULE_UNLOAD
	156	static ssize_t store_mod_unload(struct module_attribute *mattr,
	157	struct module *mod,
	158	const char *buffer, size_t count)
	159	{
	160	char name[MODULE_NAME_LEN];
	161	int ret;
	162
	163	if (count < 1 \|\| count+1 > MODULE_NAME_LEN)
	164	return -EINVAL;
	165	memcpy(name, buffer, count);
	166	name[count] = '\0';
	167	if (name[count-1] == '\n')
	168	name[count-1] = '\0';
	169
	170	ret = delete_module(name, O_NONBLOCK);
	171	if (ret < 0)
	172	return ret;
	173	return count;
	174	}
	175
	176	static struct module_attribute mod_unload = {
	177	.attr = { .name = "mod_unload", .mode = S_IWUSR, .owner = THIS_MODULE },
	178	.store = store_mod_unload,
	179	};
	180	#endif
	181
	182	static ssize_t show_mod_request_helper(struct module_attribute *mattr,
	183	struct module *mod,
	184	char *buffer)
	185	{
	186	return sprintf(buffer, "%s\n", modprobe_path);
	187	}
	188
	189	static ssize_t store_mod_request_helper(struct module_attribute *mattr,
	190	struct module *mod,
	191	const char *buffer, size_t count)
	192	{
193	if (count < 1 \|\| count+1 > KMOD_PATH_LEN)
194	return -EINVAL;
195	memcpy(modprobe_path, buffer, count);
196	modprobe_path[count] = '\0';
197	if (modprobe_path[count-1] == '\n')
198	modprobe_path[count-1] = '\0';
199	return count;
200	}
201
202	static struct module_attribute mod_request_helper = {
203	.attr = {
204	.name = "mod_request_helper",
205	.mode = S_IWUSR \| S_IRUGO,
206	.owner = THIS_MODULE
207	},
208	.show = show_mod_request_helper,
209	.store = store_mod_request_helper,
210	};
211
212	void __init kmod_sysfs_init(void)
213	{
214	int ret;
215
216	kmod_mk.mod = THIS_MODULE;
217	kobj_set_kset_s(&kmod_mk, module_subsys);
218	kobject_set_name(&kmod_mk.kobj, "kmod");
219	kobject_init(&kmod_mk.kobj);
220	ret = kobject_add(&kmod_mk.kobj);
221	if (ret < 0)
222	goto out;
223
224	ret = sysfs_create_file(&kmod_mk.kobj, &mod_request_helper.attr);
225	ret = sysfs_create_file(&kmod_mk.kobj, &mod_request.attr);
226	#ifdef CONFIG_MODULE_UNLOAD
227	ret = sysfs_create_file(&kmod_mk.kobj, &mod_unload.attr);
228	#endif
229
230	kobject_uevent(&kmod_mk.kobj, KOBJ_ADD);
231	out:
232	return;
233	}
1da177e4 LT	234	#endif /* CONFIG_KMOD */
	235
	236	struct subprocess_info {
65f27f38	237	struct work_struct work;
1da177e4 LT	238	struct completion *complete;
	239	char *path;
	240	char **argv;
	241	char **envp;
7888e7ff	242	struct key *ring;
1da177e4 LT	243	int wait;
1da177e4 LT	244	int retval;
e239ca54	245	struct file *stdin;
1da177e4 LT	246	};
	247
	248	/*
	249	* This is the task which runs the usermode application
	250	*/
	251	static int ____call_usermodehelper(void *data)
	252	{
	253	struct subprocess_info *sub_info = data;
20e1129a	254	struct key new_session, old_session;
1da177e4 LT	255	int retval;
1da177e4 LT	256
7888e7ff	257	/* Unblock all signals and set the session keyring. */
20e1129a	258	new_session = key_get(sub_info->ring);
1da177e4 LT	259	flush_signals(current);
1da177e4 LT	260	spin_lock_irq(&current->sighand->siglock);
20e1129a	261	old_session = __install_session_keyring(current, new_session);
1da177e4 LT	262	flush_signal_handlers(current, 1);
	263	sigemptyset(&current->blocked);
	264	recalc_sigpending();
	265	spin_unlock_irq(&current->sighand->siglock);
	266
7888e7ff DH	267	key_put(old_session);
7888e7ff DH	268
e239ca54 AK	269	/* Install input pipe when needed */
	270	if (sub_info->stdin) {
	271	struct files_struct *f = current->files;
	272	struct fdtable *fdt;
	273	/* no races because files should be private here */
	274	sys_close(0);
	275	fd_install(0, sub_info->stdin);
	276	spin_lock(&f->file_lock);
	277	fdt = files_fdtable(f);
	278	FD_SET(0, fdt->open_fds);
	279	FD_CLR(0, fdt->close_on_exec);
	280	spin_unlock(&f->file_lock);
d025c9db AK	281
	282	/* and disallow core files too */
	283	current->signal->rlim[RLIMIT_CORE] = (struct rlimit){0, 0};
e239ca54 AK	284	}
e239ca54 AK	285
1da177e4 LT	286	/* We can run anywhere, unlike our parent keventd(). */
	287	set_cpus_allowed(current, CPU_MASK_ALL);
	288
	289	retval = -EPERM;
	290	if (current->fs->root)
67608567 AB	291	retval = kernel_execve(sub_info->path,
67608567 AB	292	sub_info->argv, sub_info->envp);
1da177e4 LT	293
	294	/* Exec failed? */
	295	sub_info->retval = retval;
	296	do_exit(0);
	297	}
	298
	299	/* Keventd can't block, but this (a child) can. */
	300	static int wait_for_helper(void *data)
	301	{
	302	struct subprocess_info *sub_info = data;
	303	pid_t pid;
	304	struct k_sigaction sa;
	305
	306	/* Install a handler: if SIGCLD isn't handled sys_wait4 won't
	307	* populate the status, but will return -ECHILD. */
	308	sa.sa.sa_handler = SIG_IGN;
	309	sa.sa.sa_flags = 0;
	310	siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
8292d633	311	do_sigaction(SIGCHLD, &sa, NULL);
1da177e4 LT	312	allow_signal(SIGCHLD);
	313
	314	pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
	315	if (pid < 0) {
	316	sub_info->retval = pid;
	317	} else {
111dbe0c BS	318	int ret;
111dbe0c BS	319
1da177e4 LT	320	/*
	321	* Normally it is bogus to call wait4() from in-kernel because
	322	* wait4() wants to write the exit code to a userspace address.
	323	* But wait_for_helper() always runs as keventd, and put_user()
	324	* to a kernel address works OK for kernel threads, due to their
	325	* having an mm_segment_t which spans the entire address space.
	326	*
	327	* Thus the __user pointer cast is valid here.
	328	*/
111dbe0c BS	329	sys_wait4(pid, (int __user *)&ret, 0, NULL);
	330
	331	/*
	332	* If ret is 0, either ____call_usermodehelper failed and the
	333	* real error code is already in sub_info->retval or
	334	* sub_info->retval is 0 anyway, so don't mess with it then.
	335	*/
	336	if (ret)
	337	sub_info->retval = ret;
1da177e4 LT	338	}
1da177e4 LT	339
a98f0dd3 AK	340	if (sub_info->wait < 0)
	341	kfree(sub_info);
	342	else
	343	complete(sub_info->complete);
1da177e4 LT	344	return 0;
	345	}
	346
	347	/* This is run by khelper thread */
65f27f38	348	static void __call_usermodehelper(struct work_struct *work)
1da177e4	349	{
65f27f38 DH	350	struct subprocess_info *sub_info =
65f27f38 DH	351	container_of(work, struct subprocess_info, work);
1da177e4	352	pid_t pid;
e4b69aa2	353	int wait = sub_info->wait;
1da177e4 LT	354
	355	/* CLONE_VFORK: wait until the usermode helper has execve'd
	356	* successfully We need the data structures to stay around
	357	* until that is done. */
e4b69aa2	358	if (wait)
1da177e4 LT	359	pid = kernel_thread(wait_for_helper, sub_info,
	360	CLONE_FS \| CLONE_FILES \| SIGCHLD);
	361	else
	362	pid = kernel_thread(____call_usermodehelper, sub_info,
	363	CLONE_VFORK \| SIGCHLD);
	364
a98f0dd3 AK	365	if (wait < 0)
	366	return;
	367
1da177e4 LT	368	if (pid < 0) {
	369	sub_info->retval = pid;
	370	complete(sub_info->complete);
e4b69aa2	371	} else if (!wait)
1da177e4 LT	372	complete(sub_info->complete);
	373	}
	374
	375	/**
7888e7ff	376	* call_usermodehelper_keys - start a usermode application
1da177e4 LT	377	* @path: pathname for the application
	378	* @argv: null-terminated argument list
	379	* @envp: null-terminated environment list
7888e7ff	380	* @session_keyring: session keyring for process (NULL for an empty keyring)
1da177e4	381	* @wait: wait for the application to finish and return status.
a98f0dd3 AK	382	* when -1 don't wait at all, but you get no useful error back when
	383	* the program couldn't be exec'ed. This makes it safe to call
	384	* from interrupt context.
1da177e4 LT	385	*
	386	* Runs a user-space application. The application is started
	387	* asynchronously if wait is not set, and runs as a child of keventd.
	388	* (ie. it runs with full root capabilities).
	389	*
	390	* Must be called from process context. Returns a negative error code
	391	* if program was not execed successfully, or 0.
	392	*/
7888e7ff DH	393	int call_usermodehelper_keys(char path, char argv, char *envp,
7888e7ff DH	394	struct key *session_keyring, int wait)
1da177e4	395	{
60be6b9a	396	DECLARE_COMPLETION_ONSTACK(done);
a98f0dd3 AK	397	struct subprocess_info *sub_info;
a98f0dd3 AK	398	int retval;
1da177e4 LT	399
	400	if (!khelper_wq)
	401	return -EBUSY;
	402
	403	if (path[0] == '\0')
	404	return 0;
	405
a98f0dd3 AK	406	sub_info = kzalloc(sizeof(struct subprocess_info), GFP_ATOMIC);
	407	if (!sub_info)
	408	return -ENOMEM;
	409
	410	INIT_WORK(&sub_info->work, __call_usermodehelper);
	411	sub_info->complete = &done;
	412	sub_info->path = path;
	413	sub_info->argv = argv;
	414	sub_info->envp = envp;
	415	sub_info->ring = session_keyring;
	416	sub_info->wait = wait;
	417
	418	queue_work(khelper_wq, &sub_info->work);
	419	if (wait < 0) /* task has freed sub_info */
	420	return 0;
1da177e4	421	wait_for_completion(&done);
a98f0dd3 AK	422	retval = sub_info->retval;
	423	kfree(sub_info);
	424	return retval;
1da177e4	425	}
7888e7ff	426	EXPORT_SYMBOL(call_usermodehelper_keys);
1da177e4	427
e239ca54 AK	428	int call_usermodehelper_pipe(char path, char argv, char *envp,
	429	struct file **filp)
	430	{
	431	DECLARE_COMPLETION(done);
	432	struct subprocess_info sub_info = {
65f27f38 DH	433	.work = __WORK_INITIALIZER(sub_info.work,
65f27f38 DH	434	__call_usermodehelper),
e239ca54 AK	435	.complete = &done,
	436	.path = path,
	437	.argv = argv,
	438	.envp = envp,
	439	.retval = 0,
	440	};
	441	struct file *f;
e239ca54 AK	442
	443	if (!khelper_wq)
	444	return -EBUSY;
	445
	446	if (path[0] == '\0')
	447	return 0;
	448
	449	f = create_write_pipe();
3cce4856 AM	450	if (IS_ERR(f))
3cce4856 AM	451	return PTR_ERR(f);
e239ca54 AK	452	*filp = f;
	453
	454	f = create_read_pipe(f);
3cce4856	455	if (IS_ERR(f)) {
e239ca54	456	free_write_pipe(*filp);
3cce4856	457	return PTR_ERR(f);
e239ca54 AK	458	}
	459	sub_info.stdin = f;
	460
65f27f38	461	queue_work(khelper_wq, &sub_info.work);
e239ca54 AK	462	wait_for_completion(&done);
	463	return sub_info.retval;
	464	}
	465	EXPORT_SYMBOL(call_usermodehelper_pipe);
	466
1da177e4 LT	467	void __init usermodehelper_init(void)
	468	{
	469	khelper_wq = create_singlethread_workqueue("khelper");
	470	BUG_ON(!khelper_wq);
	471	}