[PATCH 02/10] Driver core: let request_module() send a /sys/modules/kmod/-uevent

Greg Kroah-Hartman
2007-02-16T23:39:08Z

From: Kay Sievers <kay.sievers@vrfy.org>

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>
---
include/linux/kmod.h | 2 +
kernel/kmod.c | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++
kernel/module.c | 26 +++++++----
kernel/params.c | 1 +
4 files changed, 139 insertions(+), 10 deletions(-)

diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index 10f505c..cc8e674 100644
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -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

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 7962761..9f923f8 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -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 {
diff --git a/kernel/module.c b/kernel/module.c
index 8a94e05..225501f 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -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;
diff --git a/kernel/params.c b/kernel/params.c
index 553cf7d..7d231c6 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -714,6 +714,7 @@ static int __init param_sysfs_init(void)
}

param_sysfs_builtin();
+ kmod_sysfs_init();

return 0;
}
--
1.5.0