// SPDX-License-Identifier: GPL-2.0-only/* * umd - User mode driver support */#include <linux/shmem_fs.h>#include <linux/pipe_fs_i.h>#include <linux/mount.h>#include <linux/fs_struct.h>#include <linux/task_work.h>#include <linux/usermode_driver.h> static struct vfsmount *blob_to_mnt(const void *data, size_t len, const char *name){	struct file_system_type *type;	struct vfsmount *mnt;	struct file *file;	ssize_t written;	loff_t pos = 0; 	type = get_fs_type("tmpfs");	if (!type)		return ERR_PTR(-ENODEV); 	mnt = kern_mount(type);	put_filesystem(type);	if (IS_ERR(mnt))		return mnt; 	file = file_open_root_mnt(mnt, name, O_CREAT | O_WRONLY, 0700);	if (IS_ERR(file)) {		kern_unmount(mnt);		return ERR_CAST(file);	} 	written = kernel_write(file, data, len, &pos);	if (written != len) {		int err = written;		if (err >= 0)			err = -ENOMEM;		filp_close(file, NULL);		kern_unmount(mnt);		return ERR_PTR(err);	} 	fput(file); 	/* Flush delayed fput so exec can open the file read-only */	flush_delayed_fput();	task_work_run();	return mnt;} /** * umd_load_blob - Remember a blob of bytes for fork_usermode_driver * @info: information about usermode driver * @data: a blob of bytes that can be executed as a file * @len:  The lentgh of the blob * */int umd_load_blob(struct umd_info *info, const void *data, size_t len){	struct vfsmount *mnt; 	if (WARN_ON_ONCE(info->wd.dentry || info->wd.mnt))		return -EBUSY; 	mnt = blob_to_mnt(data, len, info->driver_name);	if (IS_ERR(mnt))		return PTR_ERR(mnt); 	info->wd.mnt = mnt;	info->wd.dentry = mnt->mnt_root;	return 0;}EXPORT_SYMBOL_GPL(umd_load_blob); /** * umd_unload_blob - Disassociate @info from a previously loaded blob * @info: information about usermode driver * */int umd_unload_blob(struct umd_info *info){	if (WARN_ON_ONCE(!info->wd.mnt ||			 !info->wd.dentry ||			 info->wd.mnt->mnt_root != info->wd.dentry))		return -EINVAL; 	kern_unmount(info->wd.mnt);	info->wd.mnt = NULL;	info->wd.dentry = NULL;	return 0;}EXPORT_SYMBOL_GPL(umd_unload_blob); static int umd_setup(struct subprocess_info *info, struct cred *new){	struct umd_info *umd_info = info->data;	struct file *from_umh[2];	struct file *to_umh[2];	int err; 	/* create pipe to send data to umh */	err = create_pipe_files(to_umh, 0);	if (err)		return err;	err = replace_fd(0, to_umh[0], 0);	fput(to_umh[0]);	if (err < 0) {		fput(to_umh[1]);		return err;	} 	/* create pipe to receive data from umh */	err = create_pipe_files(from_umh, 0);	if (err) {		fput(to_umh[1]);		replace_fd(0, NULL, 0);		return err;	}	err = replace_fd(1, from_umh[1], 0);	fput(from_umh[1]);	if (err < 0) {		fput(to_umh[1]);		replace_fd(0, NULL, 0);		fput(from_umh[0]);		return err;	} 	set_fs_pwd(current->fs, &umd_info->wd);	umd_info->pipe_to_umh = to_umh[1];	umd_info->pipe_from_umh = from_umh[0];	umd_info->tgid = get_pid(task_tgid(current));	return 0;} static void umd_cleanup(struct subprocess_info *info){	struct umd_info *umd_info = info->data; 	/* cleanup if umh_setup() was successful but exec failed */	if (info->retval)		umd_cleanup_helper(umd_info);} /** * umd_cleanup_helper - release the resources which were allocated in umd_setup * @info: information about usermode driver */void umd_cleanup_helper(struct umd_info *info){	fput(info->pipe_to_umh);	fput(info->pipe_from_umh);	put_pid(info->tgid);	info->tgid = NULL;}EXPORT_SYMBOL_GPL(umd_cleanup_helper); /** * fork_usermode_driver - fork a usermode driver * @info: information about usermode driver (shouldn't be NULL) * * Returns either negative error or zero which indicates success in * executing a usermode driver. In such case 'struct umd_info *info' * is populated with two pipes and a tgid of the process. The caller is * responsible for health check of the user process, killing it via * tgid, and closing the pipes when user process is no longer needed. */int fork_usermode_driver(struct umd_info *info){	struct subprocess_info *sub_info;	const char *argv[] = { info->driver_name, NULL };	int err; 	if (WARN_ON_ONCE(info->tgid))		return -EBUSY; 	err = -ENOMEM;	sub_info = call_usermodehelper_setup(info->driver_name,					     (char **)argv, NULL, GFP_KERNEL,					     umd_setup, umd_cleanup, info);	if (!sub_info)		goto out; 	err = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);out:	return err;}EXPORT_SYMBOL_GPL(fork_usermode_driver);