Commit c353c3fb authored by Kay Sievers's avatar Kay Sievers Committed by Greg Kroah-Hartman
Browse files

Driver core: let request_module() send a /sys/modules/kmod/-uevent 



On recent systems, calls to /sbin/modprobe are handled by udev depending
on the kind of device the kernel has discovered. This patch creates an
uevent for the kernels internal request_module(), to let udev take control
over the request, instead of forking the binary directly by the kernel.
The direct execution of /sbin/modprobe can be disabled by setting:
  /sys/module/kmod/mod_request_helper (/proc/sys/kernel/modprobe)
to an empty string, the same way /proc/sys/kernel/hotplug is disabled on an
udev system.

Signed-off-by: default avatarKay Sievers <kay.sievers@vrfy.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 89790fd7

include/linux/kmod.h

+2 −0
Original line number Diff line number Diff line
@@ -28,8 +28,10 @@ 
#ifdef CONFIG_KMOD

/* modprobe exit status on success, -ve on error.  Return value

 * usually useless though. */

extern void kmod_sysfs_init(void);

extern int request_module(const char * name, ...) __attribute__ ((format (printf, 1, 2)));

#else

static inline void kmod_sysfs_init(void) {};

static inline int request_module(const char * name, ...) { return -ENOSYS; }

#endif

kernel/kmod.c

+120 −0
Original line number Diff line number Diff line
@@ -36,6 +36,8 @@ 
#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;
@@ -46,6 +48,7 @@ static struct workqueue_struct *khelper_wq; 
	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
@@ -75,6 +78,11 @@ int request_module(const char *fmt, ...) 
	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);
@@ -82,6 +90,12 @@ int request_module(const char *fmt, ...) 
	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
@@ -108,9 +122,115 @@ int request_module(const char *fmt, ...) 


	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 {

kernel/module.c

+16 −10
Original line number Diff line number Diff line
@@ -653,20 +653,11 @@ static void wait_for_zero_refcount(struct module *mod) 
	mutex_lock(&module_mutex);

}



asmlinkage long

sys_delete_module(const char __user *name_user, unsigned int flags)

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

{

	struct module *mod;

	char name[MODULE_NAME_LEN];

	int ret, forced = 0;



	if (!capable(CAP_SYS_MODULE))

		return -EPERM;



	if (strncpy_from_user(name, name_user, MODULE_NAME_LEN-1) < 0)

		return -EFAULT;

	name[MODULE_NAME_LEN-1] = '\0';



	if (mutex_lock_interruptible(&module_mutex) != 0)

		return -EINTR;
@@ -727,6 +718,21 @@ sys_delete_module(const char __user *name_user, unsigned int flags) 
	return ret;

}



asmlinkage long

sys_delete_module(const char __user *name_user, unsigned int flags)

{

	char name[MODULE_NAME_LEN];



	if (!capable(CAP_SYS_MODULE))

		return -EPERM;



	if (strncpy_from_user(name, name_user, MODULE_NAME_LEN-1) < 0)

		return -EFAULT;

	name[MODULE_NAME_LEN-1] = '\0';



	return delete_module(name, flags);

}



static void print_unload_info(struct seq_file *m, struct module *mod)

{

	struct module_use *use;

kernel/params.c

+1 −0
Original line number Diff line number Diff line
@@ -714,6 +714,7 @@ static int __init param_sysfs_init(void) 
	}



	param_sysfs_builtin();

	kmod_sysfs_init();



	return 0;

}

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