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: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Kay Sievers 2007-02-02 16:39:12 +01:00 committed by Greg Kroah-Hartman
parent 89790fd789
commit c353c3fb07
4 changed files with 139 additions and 10 deletions

View file

@ -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

View file

@ -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 {

View file

@ -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;

View file

@ -714,6 +714,7 @@ static int __init param_sysfs_init(void)
}
param_sysfs_builtin();
kmod_sysfs_init();
return 0;
}