fs/fuse/ioctl.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2017 Red Hat, Inc.
  */

 #include "fuse_i.h"

 #include <linux/uio.h>
 #include <linux/compat.h>
 #include <linux/fileattr.h>

 /*
  * CUSE servers compiled on 32bit broke on 64bit kernels because the
  * ABI was defined to be 'struct iovec' which is different on 32bit
  * and 64bit.  Fortunately we can determine which structure the server
  * used from the size of the reply.
  */
 static int fuse_copy_ioctl_iovec_old(struct iovec *dst, void *src,
 				     size_t transferred, unsigned count,
 				     bool is_compat)
 {
 #ifdef CONFIG_COMPAT
 	if (count * sizeof(struct compat_iovec) == transferred) {
 		struct compat_iovec *ciov = src;
 		unsigned i;

 		/*
 		 * With this interface a 32bit server cannot support
 		 * non-compat (i.e. ones coming from 64bit apps) ioctl
 		 * requests
 		 */
 		if (!is_compat)
 			return -EINVAL;

 		for (i = 0; i < count; i++) {
 			dst[i].iov_base = compat_ptr(ciov[i].iov_base);
 			dst[i].iov_len = ciov[i].iov_len;
 		}
 		return 0;
 	}
 #endif

 	if (count * sizeof(struct iovec) != transferred)
 		return -EIO;

 	memcpy(dst, src, transferred);
 	return 0;
 }

 /* Make sure iov_length() won't overflow */
 static int fuse_verify_ioctl_iov(struct fuse_conn *fc, struct iovec *iov,
 				 size_t count)
 {
 	size_t n;
 	u32 max = fc->max_pages << PAGE_SHIFT;

 	for (n = 0; n < count; n++, iov++) {
 		if (iov->iov_len > (size_t) max)
 			return -ENOMEM;
 		max -= iov->iov_len;
 	}
 	return 0;
 }

 static int fuse_copy_ioctl_iovec(struct fuse_conn *fc, struct iovec *dst,
 				 void *src, size_t transferred, unsigned count,
 				 bool is_compat)
 {
 	unsigned i;
 	struct fuse_ioctl_iovec *fiov = src;

 	if (fc->minor < 16) {
 		return fuse_copy_ioctl_iovec_old(dst, src, transferred,
 						 count, is_compat);
 	}

 	if (count * sizeof(struct fuse_ioctl_iovec) != transferred)
 		return -EIO;

 	for (i = 0; i < count; i++) {
 		/* Did the server supply an inappropriate value? */
 		if (fiov[i].base != (unsigned long) fiov[i].base ||
 		    fiov[i].len != (unsigned long) fiov[i].len)
 			return -EIO;

 		dst[i].iov_base = (void __user *) (unsigned long) fiov[i].base;
 		dst[i].iov_len = (size_t) fiov[i].len;

 #ifdef CONFIG_COMPAT
 		if (is_compat &&
 		    (ptr_to_compat(dst[i].iov_base) != fiov[i].base ||
 		     (compat_size_t) dst[i].iov_len != fiov[i].len))
 			return -EIO;
 #endif
 	}

 	return 0;
 }


 /*
  * For ioctls, there is no generic way to determine how much memory
  * needs to be read and/or written.  Furthermore, ioctls are allowed
  * to dereference the passed pointer, so the parameter requires deep
  * copying but FUSE has no idea whatsoever about what to copy in or
  * out.
  *
  * This is solved by allowing FUSE server to retry ioctl with
  * necessary in/out iovecs.  Let's assume the ioctl implementation
  * needs to read in the following structure.
  *
  * struct a {
  *	char	*buf;
  *	size_t	buflen;
  * }
  *
  * On the first callout to FUSE server, inarg->in_size and
  * inarg->out_size will be NULL; then, the server completes the ioctl
  * with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
  * the actual iov array to
  *
  * { { .iov_base = inarg.arg,	.iov_len = sizeof(struct a) } }
  *
  * which tells FUSE to copy in the requested area and retry the ioctl.
  * On the second round, the server has access to the structure and
  * from that it can tell what to look for next, so on the invocation,
  * it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
  *
  * { { .iov_base = inarg.arg,	.iov_len = sizeof(struct a)	},
  *   { .iov_base = a.buf,	.iov_len = a.buflen		} }
  *
  * FUSE will copy both struct a and the pointed buffer from the
  * process doing the ioctl and retry ioctl with both struct a and the
  * buffer.
  *
  * This time, FUSE server has everything it needs and completes ioctl
  * without FUSE_IOCTL_RETRY which finishes the ioctl call.
  *
  * Copying data out works the same way.
  *
  * Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
  * automatically initializes in and out iovs by decoding @cmd with
  * _IOC_* macros and the server is not allowed to request RETRY.  This
  * limits ioctl data transfers to well-formed ioctls and is the forced
  * behavior for all FUSE servers.
  */
 long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
 		   unsigned int flags)
 {
 	struct fuse_file *ff = file->private_data;
 	struct fuse_mount *fm = ff->fm;
 	struct fuse_ioctl_in inarg = {
 		.fh = ff->fh,
 		.cmd = cmd,
 		.arg = arg,
 		.flags = flags
 	};
 	struct fuse_ioctl_out outarg;
 	struct iovec *iov_page = NULL;
 	struct iovec *in_iov = NULL, *out_iov = NULL;
 	unsigned int in_iovs = 0, out_iovs = 0, max_pages;
 	size_t in_size, out_size, c;
 	ssize_t transferred;
 	int err, i;
 	struct iov_iter ii;
 	struct fuse_args_pages ap = {};

 #if BITS_PER_LONG == 32
 	inarg.flags |= FUSE_IOCTL_32BIT;
 #else
 	if (flags & FUSE_IOCTL_COMPAT) {
 		inarg.flags |= FUSE_IOCTL_32BIT;
 #ifdef CONFIG_X86_X32
 		if (in_x32_syscall())
 			inarg.flags |= FUSE_IOCTL_COMPAT_X32;
 #endif
 	}
 #endif

 	/* assume all the iovs returned by client always fits in a page */
 	BUILD_BUG_ON(sizeof(struct fuse_ioctl_iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);

 	err = -ENOMEM;
 	ap.pages = fuse_pages_alloc(fm->fc->max_pages, GFP_KERNEL, &ap.descs);
 	iov_page = (struct iovec *) __get_free_page(GFP_KERNEL);
 	if (!ap.pages || !iov_page)
 		goto out;

 	fuse_page_descs_length_init(ap.descs, 0, fm->fc->max_pages);

 	/*
 	 * If restricted, initialize IO parameters as encoded in @cmd.
 	 * RETRY from server is not allowed.
 	 */
 	if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
 		struct iovec *iov = iov_page;

 		iov->iov_base = (void __user *)arg;
 		iov->iov_len = _IOC_SIZE(cmd);

 		if (_IOC_DIR(cmd) & _IOC_WRITE) {
 			in_iov = iov;
 			in_iovs = 1;
 		}

 		if (_IOC_DIR(cmd) & _IOC_READ) {
 			out_iov = iov;
 			out_iovs = 1;
 		}
 	}

  retry:
 	inarg.in_size = in_size = iov_length(in_iov, in_iovs);
 	inarg.out_size = out_size = iov_length(out_iov, out_iovs);

 	/*
 	 * Out data can be used either for actual out data or iovs,
 	 * make sure there always is at least one page.
 	 */
 	out_size = max_t(size_t, out_size, PAGE_SIZE);
 	max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);

 	/* make sure there are enough buffer pages and init request with them */
 	err = -ENOMEM;
 	if (max_pages > fm->fc->max_pages)
 		goto out;
 	while (ap.num_pages < max_pages) {
 		ap.pages[ap.num_pages] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
 		if (!ap.pages[ap.num_pages])
 			goto out;
 		ap.num_pages++;
 	}


 	/* okay, let's send it to the client */
 	ap.args.opcode = FUSE_IOCTL;
 	ap.args.nodeid = ff->nodeid;
 	ap.args.in_numargs = 1;
 	ap.args.in_args[0].size = sizeof(inarg);
 	ap.args.in_args[0].value = &inarg;
 	if (in_size) {
 		ap.args.in_numargs++;
 		ap.args.in_args[1].size = in_size;
 		ap.args.in_pages = true;

 		err = -EFAULT;
 		iov_iter_init(&ii, WRITE, in_iov, in_iovs, in_size);
 		for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
 			c = copy_page_from_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
 			if (c != PAGE_SIZE && iov_iter_count(&ii))
 				goto out;
 		}
 	}

 	ap.args.out_numargs = 2;
 	ap.args.out_args[0].size = sizeof(outarg);
 	ap.args.out_args[0].value = &outarg;
 	ap.args.out_args[1].size = out_size;
 	ap.args.out_pages = true;
 	ap.args.out_argvar = true;

 	transferred = fuse_simple_request(fm, &ap.args);
 	err = transferred;
 	if (transferred < 0)
 		goto out;

 	/* did it ask for retry? */
 	if (outarg.flags & FUSE_IOCTL_RETRY) {
 		void *vaddr;

 		/* no retry if in restricted mode */
 		err = -EIO;
 		if (!(flags & FUSE_IOCTL_UNRESTRICTED))
 			goto out;

 		in_iovs = outarg.in_iovs;
 		out_iovs = outarg.out_iovs;

 		/*
 		 * Make sure things are in boundary, separate checks
 		 * are to protect against overflow.
 		 */
 		err = -ENOMEM;
 		if (in_iovs > FUSE_IOCTL_MAX_IOV ||
 		    out_iovs > FUSE_IOCTL_MAX_IOV ||
 		    in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
 			goto out;

 		vaddr = kmap_atomic(ap.pages[0]);
 		err = fuse_copy_ioctl_iovec(fm->fc, iov_page, vaddr,
 					    transferred, in_iovs + out_iovs,
 					    (flags & FUSE_IOCTL_COMPAT) != 0);
 		kunmap_atomic(vaddr);
 		if (err)
 			goto out;

 		in_iov = iov_page;
 		out_iov = in_iov + in_iovs;

 		err = fuse_verify_ioctl_iov(fm->fc, in_iov, in_iovs);
 		if (err)
 			goto out;

 		err = fuse_verify_ioctl_iov(fm->fc, out_iov, out_iovs);
 		if (err)
 			goto out;

 		goto retry;
 	}

 	err = -EIO;
 	if (transferred > inarg.out_size)
 		goto out;

 	err = -EFAULT;
 	iov_iter_init(&ii, READ, out_iov, out_iovs, transferred);
 	for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
 		c = copy_page_to_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
 		if (c != PAGE_SIZE && iov_iter_count(&ii))
 			goto out;
 	}
 	err = 0;
  out:
 	free_page((unsigned long) iov_page);
 	while (ap.num_pages)
 		__free_page(ap.pages[--ap.num_pages]);
 	kfree(ap.pages);

 	return err ? err : outarg.result;
 }
 EXPORT_SYMBOL_GPL(fuse_do_ioctl);

 long fuse_ioctl_common(struct file *file, unsigned int cmd,
 		       unsigned long arg, unsigned int flags)
 {
 	struct inode *inode = file_inode(file);
 	struct fuse_conn *fc = get_fuse_conn(inode);

 	if (!fuse_allow_current_process(fc))
 		return -EACCES;

 	if (fuse_is_bad(inode))
 		return -EIO;

 	return fuse_do_ioctl(file, cmd, arg, flags);
 }

 long fuse_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
 	return fuse_ioctl_common(file, cmd, arg, 0);
 }

 long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
 			    unsigned long arg)
 {
 	return fuse_ioctl_common(file, cmd, arg, FUSE_IOCTL_COMPAT);
 }

 static int fuse_priv_ioctl(struct inode *inode, struct fuse_file *ff,
 			   unsigned int cmd, void *ptr, size_t size)
 {
 	struct fuse_mount *fm = ff->fm;
 	struct fuse_ioctl_in inarg;
 	struct fuse_ioctl_out outarg;
 	FUSE_ARGS(args);
 	int err;

 	memset(&inarg, 0, sizeof(inarg));
 	inarg.fh = ff->fh;
 	inarg.cmd = cmd;

 #if BITS_PER_LONG == 32
 	inarg.flags |= FUSE_IOCTL_32BIT;
 #endif
 	if (S_ISDIR(inode->i_mode))
 		inarg.flags |= FUSE_IOCTL_DIR;

 	if (_IOC_DIR(cmd) & _IOC_READ)
 		inarg.out_size = size;
 	if (_IOC_DIR(cmd) & _IOC_WRITE)
 		inarg.in_size = size;

 	args.opcode = FUSE_IOCTL;
 	args.nodeid = ff->nodeid;
 	args.in_numargs = 2;
 	args.in_args[0].size = sizeof(inarg);
 	args.in_args[0].value = &inarg;
 	args.in_args[1].size = inarg.in_size;
 	args.in_args[1].value = ptr;
 	args.out_numargs = 2;
 	args.out_args[0].size = sizeof(outarg);
 	args.out_args[0].value = &outarg;
 	args.out_args[1].size = inarg.out_size;
 	args.out_args[1].value = ptr;

 	err = fuse_simple_request(fm, &args);
 	if (!err && outarg.flags & FUSE_IOCTL_RETRY)
 		err = -EIO;

 	return err;
 }

 static struct fuse_file *fuse_priv_ioctl_prepare(struct inode *inode)
 {
 	struct fuse_mount *fm = get_fuse_mount(inode);
 	bool isdir = S_ISDIR(inode->i_mode);

 	if (!S_ISREG(inode->i_mode) && !isdir)
 		return ERR_PTR(-ENOTTY);

 	return fuse_file_open(fm, get_node_id(inode), O_RDONLY, isdir);
 }

 static void fuse_priv_ioctl_cleanup(struct inode *inode, struct fuse_file *ff)
 {
 	fuse_file_release(inode, ff, O_RDONLY, NULL, S_ISDIR(inode->i_mode));
 }

 int fuse_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 {
 	struct inode *inode = d_inode(dentry);
 	struct fuse_file *ff;
 	unsigned int flags;
 	struct fsxattr xfa;
 	int err;

 	ff = fuse_priv_ioctl_prepare(inode);
 	if (IS_ERR(ff))
 		return PTR_ERR(ff);

 	if (fa->flags_valid) {
 		err = fuse_priv_ioctl(inode, ff, FS_IOC_GETFLAGS,
 				      &flags, sizeof(flags));
 		if (err)
 			goto cleanup;

 		fileattr_fill_flags(fa, flags);
 	} else {
 		err = fuse_priv_ioctl(inode, ff, FS_IOC_FSGETXATTR,
 				      &xfa, sizeof(xfa));
 		if (err)
 			goto cleanup;

 		fileattr_fill_xflags(fa, xfa.fsx_xflags);
 		fa->fsx_extsize = xfa.fsx_extsize;
 		fa->fsx_nextents = xfa.fsx_nextents;
 		fa->fsx_projid = xfa.fsx_projid;
 		fa->fsx_cowextsize = xfa.fsx_cowextsize;
 	}
 cleanup:
 	fuse_priv_ioctl_cleanup(inode, ff);

 	return err;
 }

 int fuse_fileattr_set(struct user_namespace *mnt_userns,
 		      struct dentry *dentry, struct fileattr *fa)
 {
 	struct inode *inode = d_inode(dentry);
 	struct fuse_file *ff;
 	unsigned int flags = fa->flags;
 	struct fsxattr xfa;
 	int err;

 	ff = fuse_priv_ioctl_prepare(inode);
 	if (IS_ERR(ff))
 		return PTR_ERR(ff);

 	if (fa->flags_valid) {
 		err = fuse_priv_ioctl(inode, ff, FS_IOC_SETFLAGS,
 				      &flags, sizeof(flags));
 		if (err)
 			goto cleanup;
 	} else {
 		memset(&xfa, 0, sizeof(xfa));
 		xfa.fsx_xflags = fa->fsx_xflags;
 		xfa.fsx_extsize = fa->fsx_extsize;
 		xfa.fsx_nextents = fa->fsx_nextents;
 		xfa.fsx_projid = fa->fsx_projid;
 		xfa.fsx_cowextsize = fa->fsx_cowextsize;

 		err = fuse_priv_ioctl(inode, ff, FS_IOC_FSSETXATTR,
 				      &xfa, sizeof(xfa));
 	}

 cleanup:
 	fuse_priv_ioctl_cleanup(inode, ff);

 	return err;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (C) 2017 Red Hat, Inc.
	*/

	#include "fuse_i.h"

	#include <linux/uio.h>
	#include <linux/compat.h>
	#include <linux/fileattr.h>

	/*
	* CUSE servers compiled on 32bit broke on 64bit kernels because the
	* ABI was defined to be 'struct iovec' which is different on 32bit
	* and 64bit. Fortunately we can determine which structure the server
	* used from the size of the reply.
	*/
	static int fuse_copy_ioctl_iovec_old(struct iovec dst, void src,
	size_t transferred, unsigned count,
	bool is_compat)
	{
	#ifdef CONFIG_COMPAT
	if (count * sizeof(struct compat_iovec) == transferred) {
	struct compat_iovec *ciov = src;
	unsigned i;

	/*
	* With this interface a 32bit server cannot support
	* non-compat (i.e. ones coming from 64bit apps) ioctl
	* requests
	*/
	if (!is_compat)
	return -EINVAL;

	for (i = 0; i < count; i++) {
	dst[i].iov_base = compat_ptr(ciov[i].iov_base);
	dst[i].iov_len = ciov[i].iov_len;
	}
	return 0;
	}
	#endif

	if (count * sizeof(struct iovec) != transferred)
	return -EIO;

	memcpy(dst, src, transferred);
	return 0;
	}

	/* Make sure iov_length() won't overflow */
	static int fuse_verify_ioctl_iov(struct fuse_conn fc, struct iovec iov,
	size_t count)
	{
	size_t n;
	u32 max = fc->max_pages << PAGE_SHIFT;

	for (n = 0; n < count; n++, iov++) {
	if (iov->iov_len > (size_t) max)
	return -ENOMEM;
	max -= iov->iov_len;
	}
	return 0;
	}

	static int fuse_copy_ioctl_iovec(struct fuse_conn fc, struct iovec dst,
	void *src, size_t transferred, unsigned count,
	bool is_compat)
	{
	unsigned i;
	struct fuse_ioctl_iovec *fiov = src;

	if (fc->minor < 16) {
	return fuse_copy_ioctl_iovec_old(dst, src, transferred,
	count, is_compat);
	}

	if (count * sizeof(struct fuse_ioctl_iovec) != transferred)
	return -EIO;

	for (i = 0; i < count; i++) {
	/* Did the server supply an inappropriate value? */
	if (fiov[i].base != (unsigned long) fiov[i].base \|\|
	fiov[i].len != (unsigned long) fiov[i].len)
	return -EIO;

	dst[i].iov_base = (void __user *) (unsigned long) fiov[i].base;
	dst[i].iov_len = (size_t) fiov[i].len;

	#ifdef CONFIG_COMPAT
	if (is_compat &&
	(ptr_to_compat(dst[i].iov_base) != fiov[i].base \|\|
	(compat_size_t) dst[i].iov_len != fiov[i].len))
	return -EIO;
	#endif
	}

	return 0;
	}


	/*
	* For ioctls, there is no generic way to determine how much memory
	* needs to be read and/or written. Furthermore, ioctls are allowed
	* to dereference the passed pointer, so the parameter requires deep
	* copying but FUSE has no idea whatsoever about what to copy in or
	* out.
	*
	* This is solved by allowing FUSE server to retry ioctl with
	* necessary in/out iovecs. Let's assume the ioctl implementation
	* needs to read in the following structure.
	*
	* struct a {
	* char *buf;
	* size_t buflen;
	* }
	*
	* On the first callout to FUSE server, inarg->in_size and
	* inarg->out_size will be NULL; then, the server completes the ioctl
	* with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
	* the actual iov array to
	*
	* { { .iov_base = inarg.arg, .iov_len = sizeof(struct a) } }
	*
	* which tells FUSE to copy in the requested area and retry the ioctl.
	* On the second round, the server has access to the structure and
	* from that it can tell what to look for next, so on the invocation,
	* it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
	*
	* { { .iov_base = inarg.arg, .iov_len = sizeof(struct a) },
	* { .iov_base = a.buf, .iov_len = a.buflen } }
	*
	* FUSE will copy both struct a and the pointed buffer from the
	* process doing the ioctl and retry ioctl with both struct a and the
	* buffer.
	*
	* This time, FUSE server has everything it needs and completes ioctl
	* without FUSE_IOCTL_RETRY which finishes the ioctl call.
	*
	* Copying data out works the same way.
	*
	* Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
	* automatically initializes in and out iovs by decoding @cmd with
	* _IOC_* macros and the server is not allowed to request RETRY. This
	* limits ioctl data transfers to well-formed ioctls and is the forced
	* behavior for all FUSE servers.
	*/
	long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
	unsigned int flags)
	{
	struct fuse_file *ff = file->private_data;
	struct fuse_mount *fm = ff->fm;
	struct fuse_ioctl_in inarg = {
	.fh = ff->fh,
	.cmd = cmd,
	.arg = arg,
	.flags = flags
	};
	struct fuse_ioctl_out outarg;
	struct iovec *iov_page = NULL;
	struct iovec in_iov = NULL, out_iov = NULL;
	unsigned int in_iovs = 0, out_iovs = 0, max_pages;
	size_t in_size, out_size, c;
	ssize_t transferred;
	int err, i;
	struct iov_iter ii;
	struct fuse_args_pages ap = {};

	#if BITS_PER_LONG == 32
	inarg.flags \|= FUSE_IOCTL_32BIT;
	#else
	if (flags & FUSE_IOCTL_COMPAT) {
	inarg.flags \|= FUSE_IOCTL_32BIT;
	#ifdef CONFIG_X86_X32
	if (in_x32_syscall())
	inarg.flags \|= FUSE_IOCTL_COMPAT_X32;
	#endif
	}
	#endif

	/* assume all the iovs returned by client always fits in a page */
	BUILD_BUG_ON(sizeof(struct fuse_ioctl_iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);

	err = -ENOMEM;
	ap.pages = fuse_pages_alloc(fm->fc->max_pages, GFP_KERNEL, &ap.descs);
	iov_page = (struct iovec *) __get_free_page(GFP_KERNEL);
	if (!ap.pages \|\| !iov_page)
	goto out;

	fuse_page_descs_length_init(ap.descs, 0, fm->fc->max_pages);

	/*
	* If restricted, initialize IO parameters as encoded in @cmd.
	* RETRY from server is not allowed.
	*/
	if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
	struct iovec *iov = iov_page;

	iov->iov_base = (void __user *)arg;
	iov->iov_len = _IOC_SIZE(cmd);

	if (_IOC_DIR(cmd) & _IOC_WRITE) {
	in_iov = iov;
	in_iovs = 1;
	}

	if (_IOC_DIR(cmd) & _IOC_READ) {
	out_iov = iov;
	out_iovs = 1;
	}
	}

	retry:
	inarg.in_size = in_size = iov_length(in_iov, in_iovs);
	inarg.out_size = out_size = iov_length(out_iov, out_iovs);

	/*
	* Out data can be used either for actual out data or iovs,
	* make sure there always is at least one page.
	*/
	out_size = max_t(size_t, out_size, PAGE_SIZE);
	max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);

	/* make sure there are enough buffer pages and init request with them */
	err = -ENOMEM;
	if (max_pages > fm->fc->max_pages)
	goto out;
	while (ap.num_pages < max_pages) {
	ap.pages[ap.num_pages] = alloc_page(GFP_KERNEL \| __GFP_HIGHMEM);
	if (!ap.pages[ap.num_pages])
	goto out;
	ap.num_pages++;
	}


	/* okay, let's send it to the client */
	ap.args.opcode = FUSE_IOCTL;
	ap.args.nodeid = ff->nodeid;
	ap.args.in_numargs = 1;
	ap.args.in_args[0].size = sizeof(inarg);
	ap.args.in_args[0].value = &inarg;
	if (in_size) {
	ap.args.in_numargs++;
	ap.args.in_args[1].size = in_size;
	ap.args.in_pages = true;

	err = -EFAULT;
	iov_iter_init(&ii, WRITE, in_iov, in_iovs, in_size);
	for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
	c = copy_page_from_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
	if (c != PAGE_SIZE && iov_iter_count(&ii))
	goto out;
	}
	}

	ap.args.out_numargs = 2;
	ap.args.out_args[0].size = sizeof(outarg);
	ap.args.out_args[0].value = &outarg;
	ap.args.out_args[1].size = out_size;
	ap.args.out_pages = true;
	ap.args.out_argvar = true;

	transferred = fuse_simple_request(fm, &ap.args);
	err = transferred;
	if (transferred < 0)
	goto out;

	/* did it ask for retry? */
	if (outarg.flags & FUSE_IOCTL_RETRY) {
	void *vaddr;

	/* no retry if in restricted mode */
	err = -EIO;
	if (!(flags & FUSE_IOCTL_UNRESTRICTED))
	goto out;

	in_iovs = outarg.in_iovs;
	out_iovs = outarg.out_iovs;

	/*
	* Make sure things are in boundary, separate checks
	* are to protect against overflow.
	*/
	err = -ENOMEM;
	if (in_iovs > FUSE_IOCTL_MAX_IOV \|\|
	out_iovs > FUSE_IOCTL_MAX_IOV \|\|
	in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
	goto out;

	vaddr = kmap_atomic(ap.pages[0]);
	err = fuse_copy_ioctl_iovec(fm->fc, iov_page, vaddr,
	transferred, in_iovs + out_iovs,
	(flags & FUSE_IOCTL_COMPAT) != 0);
	kunmap_atomic(vaddr);
	if (err)
	goto out;

	in_iov = iov_page;
	out_iov = in_iov + in_iovs;

	err = fuse_verify_ioctl_iov(fm->fc, in_iov, in_iovs);
	if (err)
	goto out;

	err = fuse_verify_ioctl_iov(fm->fc, out_iov, out_iovs);
	if (err)
	goto out;

	goto retry;
	}

	err = -EIO;
	if (transferred > inarg.out_size)
	goto out;

	err = -EFAULT;
	iov_iter_init(&ii, READ, out_iov, out_iovs, transferred);
	for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
	c = copy_page_to_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
	if (c != PAGE_SIZE && iov_iter_count(&ii))
	goto out;
	}
	err = 0;
	out:
	free_page((unsigned long) iov_page);
	while (ap.num_pages)
	__free_page(ap.pages[--ap.num_pages]);
	kfree(ap.pages);

	return err ? err : outarg.result;
	}
	EXPORT_SYMBOL_GPL(fuse_do_ioctl);

	long fuse_ioctl_common(struct file *file, unsigned int cmd,
	unsigned long arg, unsigned int flags)
	{
	struct inode *inode = file_inode(file);
	struct fuse_conn *fc = get_fuse_conn(inode);

	if (!fuse_allow_current_process(fc))
	return -EACCES;

	if (fuse_is_bad(inode))
	return -EIO;

	return fuse_do_ioctl(file, cmd, arg, flags);
	}

	long fuse_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
	{
	return fuse_ioctl_common(file, cmd, arg, 0);
	}

	long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
	unsigned long arg)
	{
	return fuse_ioctl_common(file, cmd, arg, FUSE_IOCTL_COMPAT);
	}

	static int fuse_priv_ioctl(struct inode inode, struct fuse_file ff,
	unsigned int cmd, void *ptr, size_t size)
	{
	struct fuse_mount *fm = ff->fm;
	struct fuse_ioctl_in inarg;
	struct fuse_ioctl_out outarg;
	FUSE_ARGS(args);
	int err;

	memset(&inarg, 0, sizeof(inarg));
	inarg.fh = ff->fh;
	inarg.cmd = cmd;

	#if BITS_PER_LONG == 32
	inarg.flags \|= FUSE_IOCTL_32BIT;
	#endif
	if (S_ISDIR(inode->i_mode))
	inarg.flags \|= FUSE_IOCTL_DIR;

	if (_IOC_DIR(cmd) & _IOC_READ)
	inarg.out_size = size;
	if (_IOC_DIR(cmd) & _IOC_WRITE)
	inarg.in_size = size;

	args.opcode = FUSE_IOCTL;
	args.nodeid = ff->nodeid;
	args.in_numargs = 2;
	args.in_args[0].size = sizeof(inarg);
	args.in_args[0].value = &inarg;
	args.in_args[1].size = inarg.in_size;
	args.in_args[1].value = ptr;
	args.out_numargs = 2;
	args.out_args[0].size = sizeof(outarg);
	args.out_args[0].value = &outarg;
	args.out_args[1].size = inarg.out_size;
	args.out_args[1].value = ptr;

	err = fuse_simple_request(fm, &args);
	if (!err && outarg.flags & FUSE_IOCTL_RETRY)
	err = -EIO;

	return err;
	}

	static struct fuse_file fuse_priv_ioctl_prepare(struct inode inode)
	{
	struct fuse_mount *fm = get_fuse_mount(inode);
	bool isdir = S_ISDIR(inode->i_mode);

	if (!S_ISREG(inode->i_mode) && !isdir)
	return ERR_PTR(-ENOTTY);

	return fuse_file_open(fm, get_node_id(inode), O_RDONLY, isdir);
	}

	static void fuse_priv_ioctl_cleanup(struct inode inode, struct fuse_file ff)
	{
	fuse_file_release(inode, ff, O_RDONLY, NULL, S_ISDIR(inode->i_mode));
	}

	int fuse_fileattr_get(struct dentry dentry, struct fileattr fa)
	{
	struct inode *inode = d_inode(dentry);
	struct fuse_file *ff;
	unsigned int flags;
	struct fsxattr xfa;
	int err;

	ff = fuse_priv_ioctl_prepare(inode);
	if (IS_ERR(ff))
	return PTR_ERR(ff);

	if (fa->flags_valid) {
	err = fuse_priv_ioctl(inode, ff, FS_IOC_GETFLAGS,
	&flags, sizeof(flags));
	if (err)
	goto cleanup;

	fileattr_fill_flags(fa, flags);
	} else {
	err = fuse_priv_ioctl(inode, ff, FS_IOC_FSGETXATTR,
	&xfa, sizeof(xfa));
	if (err)
	goto cleanup;

	fileattr_fill_xflags(fa, xfa.fsx_xflags);
	fa->fsx_extsize = xfa.fsx_extsize;
	fa->fsx_nextents = xfa.fsx_nextents;
	fa->fsx_projid = xfa.fsx_projid;
	fa->fsx_cowextsize = xfa.fsx_cowextsize;
	}
	cleanup:
	fuse_priv_ioctl_cleanup(inode, ff);

	return err;
	}

	int fuse_fileattr_set(struct user_namespace *mnt_userns,
	struct dentry dentry, struct fileattr fa)
	{
	struct inode *inode = d_inode(dentry);
	struct fuse_file *ff;
	unsigned int flags = fa->flags;
	struct fsxattr xfa;
	int err;

	ff = fuse_priv_ioctl_prepare(inode);
	if (IS_ERR(ff))
	return PTR_ERR(ff);

	if (fa->flags_valid) {
	err = fuse_priv_ioctl(inode, ff, FS_IOC_SETFLAGS,
	&flags, sizeof(flags));
	if (err)
	goto cleanup;
	} else {
	memset(&xfa, 0, sizeof(xfa));
	xfa.fsx_xflags = fa->fsx_xflags;
	xfa.fsx_extsize = fa->fsx_extsize;
	xfa.fsx_nextents = fa->fsx_nextents;
	xfa.fsx_projid = fa->fsx_projid;
	xfa.fsx_cowextsize = fa->fsx_cowextsize;

	err = fuse_priv_ioctl(inode, ff, FS_IOC_FSSETXATTR,
	&xfa, sizeof(xfa));
	}

	cleanup:
	fuse_priv_ioctl_cleanup(inode, ff);

	return err;
	}