コード例 #1
0
/**
 * __request_module - try to load a kernel module
 * @wait: wait (or not) for the operation to complete
 * @fmt: printf style format string for the name of the module
 * @...: arguments 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(bool wait, 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;

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

	ret = security_kernel_module_request(module_name);
	if (ret)
		return ret;

	/* 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;
	}

	trace_module_request(module_name, wait, _RET_IP_);

	ret = call_usermodehelper_fns(modprobe_path, argv, envp,
			wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC,
			NULL, NULL, NULL);

	atomic_dec(&kmod_concurrent);
	return ret;
}
コード例 #2
0
int __request_module(bool wait, 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	
	static int kmod_loop_msg;

	ret = security_kernel_module_request();
	if (ret)
		return ret;

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

	
	max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
	atomic_inc(&kmod_concurrent);
	if (atomic_read(&kmod_concurrent) > max_modprobes) {
		
		if (kmod_loop_msg++ < 5)
			printk(KERN_ERR
			       "request_module: runaway loop modprobe %s\n",
			       module_name);
		atomic_dec(&kmod_concurrent);
		return -ENOMEM;
	}

	trace_module_request(module_name, wait, _RET_IP_);

	ret = call_usermodehelper(modprobe_path, argv, envp,
			wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
	atomic_dec(&kmod_concurrent);
	return ret;
}