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.

Kay Sievers committed 19 years ago

Commit c353c3f1 parent 89790fd4 files · +139 −10Browse files

Unified · Split

4 files

include/linux/kmod.h +2 −0
kernel/kmod.c +120 −0
kernel/module.c +16 −10
kernel/params.c +1 −0

include/linux/kmod.h+2−0

 #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

@@ -36,6 +36,8 @@ · 35 unmodified lines
36	#include <linux/resource.h>	36	#include <linux/resource.h>
37	#include <asm/uaccess.h>	37	#include <asm/uaccess.h>
38		38
		39	extern int delete_module(const char *name, unsigned int flags);
		40
39	extern int max_threads;	41	extern int max_threads;
40		42
41	static struct workqueue_struct *khelper_wq;	43	static struct workqueue_struct *khelper_wq;
@@ -46,6 +48,7 @@ static struct workqueue_struct *khelper_wq; · 4 unmodified lines
46	modprobe_path is set via /proc/sys.	48	modprobe_path is set via /proc/sys.
47	*/	49	*/
48	char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";	50	char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
		51	struct module_kobject kmod_mk;
49		52
50	/**	53	/**
51	* request_module - try to load a kernel module	54	* request_module - try to load a kernel module
@@ -75,6 +78,11 @@ int request_module(const char *fmt, ...) · 23 unmodified lines
75	static atomic_t kmod_concurrent = ATOMIC_INIT(0);	78	static atomic_t kmod_concurrent = ATOMIC_INIT(0);
76	#define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */	79	#define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */
77	static int kmod_loop_msg;	80	static int kmod_loop_msg;
		81	char modalias[16 + MODULE_NAME_LEN] = "MODALIAS=";
		82	char *uevent_envp[2] = {
		83	modalias,
		84	NULL
		85	};
78		86
79	va_start(args, fmt);	87	va_start(args, fmt);
80	ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);	88	ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
@@ -82,6 +90,12 @@ int request_module(const char *fmt, ...) · 1 unmodified line
82	if (ret >= MODULE_NAME_LEN)	90	if (ret >= MODULE_NAME_LEN)
83	return -ENAMETOOLONG;	91	return -ENAMETOOLONG;
84		92
		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
85	/* If modprobe needs a service that is in a module, we get a recursive	99	/* If modprobe needs a service that is in a module, we get a recursive
86	* loop. Limit the number of running kmod threads to max_threads/2 or	100	* loop. Limit the number of running kmod threads to max_threads/2 or
87	* MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method	101	* MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method
@@ -108,9 +122,115 @@ int request_module(const char *fmt, ...) · 20 unmodified lines
108		122
109	ret = call_usermodehelper(modprobe_path, argv, envp, 1);	123	ret = call_usermodehelper(modprobe_path, argv, envp, 1);
110	atomic_dec(&kmod_concurrent);	124	atomic_dec(&kmod_concurrent);
		125	out:
111	return ret;	126	return ret;
112	}	127	}
113	EXPORT_SYMBOL(request_module);	128	EXPORT_SYMBOL(request_module);
		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	}
114	#endif /* CONFIG_KMOD */	234	#endif /* CONFIG_KMOD */
115		235
116	struct subprocess_info {	236	struct subprocess_info {

kernel/module.c+16−10

 	mutex_lock(&module_mutex);
 }
-asmlinkage long
+int delete_module(const char *name, unsigned int flags)
-sys_delete_module(const char __user *name_user, 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;
 	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

@@ -714,6 +714,7 @@ static int __init param_sysfs_init(void) · 713 unmodified lines
714	}	714	}
715		715
716	param_sysfs_builtin();	716	param_sysfs_builtin();
		717	kmod_sysfs_init();
717		718
718	return 0;	719	return 0;
719	}	720	}