Commit 96e6e8f4 authored by Amir Goldstein's avatar Amir Goldstein Committed by Darrick J. Wong
Browse files

vfs: add missing checks to copy_file_range 



Like the clone and dedupe interfaces we've recently fixed, the
copy_file_range() implementation is missing basic sanity, limits and
boundary condition tests on the parameters that are passed to it
from userspace. Create a new "generic_copy_file_checks()" function
modelled on the generic_remap_checks() function to provide this
missing functionality.

[Amir] Shorten copy length instead of checking pos_in limits
because input file size already abides by the limits.

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent 646955cd

fs/read_write.c

+2 −1
Original line number Diff line number Diff line
@@ -1626,7 +1626,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, 
	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)

		return -EXDEV;



	ret = generic_file_rw_checks(file_in, file_out);

	ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,

				       flags);

	if (unlikely(ret))

		return ret;

include/linux/fs.h

+3 −0
Original line number Diff line number Diff line
@@ -3050,6 +3050,9 @@ extern int generic_remap_checks(struct file *file_in, loff_t pos_in, 
				struct file *file_out, loff_t pos_out,

				loff_t *count, unsigned int remap_flags);

extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);

extern int generic_copy_file_checks(struct file *file_in, loff_t pos_in,

				    struct file *file_out, loff_t pos_out,

				    size_t *count, unsigned int flags);

extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);

extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);

extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);

mm/filemap.c

+53 −0
Original line number Diff line number Diff line
@@ -3056,6 +3056,59 @@ int generic_file_rw_checks(struct file *file_in, struct file *file_out) 
	return 0;

}



/*

 * Performs necessary checks before doing a file copy

 *

 * Can adjust amount of bytes to copy via @req_count argument.

 * Returns appropriate error code that caller should return or

 * zero in case the copy should be allowed.

 */

int generic_copy_file_checks(struct file *file_in, loff_t pos_in,

			     struct file *file_out, loff_t pos_out,

			     size_t *req_count, unsigned int flags)

{

	struct inode *inode_in = file_inode(file_in);

	struct inode *inode_out = file_inode(file_out);

	uint64_t count = *req_count;

	loff_t size_in;

	int ret;



	ret = generic_file_rw_checks(file_in, file_out);

	if (ret)

		return ret;



	/* Don't touch certain kinds of inodes */

	if (IS_IMMUTABLE(inode_out))

		return -EPERM;



	if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))

		return -ETXTBSY;



	/* Ensure offsets don't wrap. */

	if (pos_in + count < pos_in || pos_out + count < pos_out)

		return -EOVERFLOW;



	/* Shorten the copy to EOF */

	size_in = i_size_read(inode_in);

	if (pos_in >= size_in)

		count = 0;

	else

		count = min(count, size_in - (uint64_t)pos_in);



	ret = generic_write_check_limits(file_out, pos_out, &count);

	if (ret)

		return ret;



	/* Don't allow overlapped copying within the same file. */

	if (inode_in == inode_out &&

	    pos_out + count > pos_in &&

	    pos_out < pos_in + count)

		return -EINVAL;



	*req_count = count;

	return 0;

}



int pagecache_write_begin(struct file *file, struct address_space *mapping,

				loff_t pos, unsigned len, unsigned flags,

				struct page **pagep, void **fsdata)

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