Commit e9734653 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Eric Biggers
Browse files

fs,fsverity: reject size changes on fsverity files in setattr_prepare 



Add the check to reject truncates of fsverity files directly to
setattr_prepare instead of requiring the file system to handle it.
Besides removing boilerplate code, this also fixes the complete lack of
such check in btrfs.

Fixes: 14605409 ("btrfs: initial fsverity support")
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatar"Darrick J. Wong" <djwong@kernel.org>
Link: https://lore.kernel.org/r/20260128152630.627409-2-hch@lst.de


Signed-off-by: default avatarEric Biggers <ebiggers@kernel.org>
parent 63804fed

fs/attr.c

+11 −1
Original line number Diff line number Diff line
@@ -169,7 +169,17 @@ int setattr_prepare(struct mnt_idmap *idmap, struct dentry *dentry, 
	 * ATTR_FORCE.

	 */

	if (ia_valid & ATTR_SIZE) {

		int error = inode_newsize_ok(inode, attr->ia_size);

		int error;



		/*

		 * Verity files are immutable, so deny truncates.  This isn't

		 * covered by the open-time check because sys_truncate() takes a

		 * path, not an open file.

		 */

		if (IS_ENABLED(CONFIG_FS_VERITY) && IS_VERITY(inode))

			return -EPERM;



		error = inode_newsize_ok(inode, attr->ia_size);

		if (error)

			return error;

	}

fs/ext4/inode.c

+0 −4
Original line number Diff line number Diff line
@@ -5835,10 +5835,6 @@ int ext4_setattr(struct mnt_idmap *idmap, struct dentry *dentry, 
	if (error)

		return error;



	error = fsverity_prepare_setattr(dentry, attr);

	if (error)

		return error;



	if (is_quota_modification(idmap, inode, attr)) {

		error = dquot_initialize(inode);

		if (error)

fs/f2fs/file.c

+0 −4
Original line number Diff line number Diff line
@@ -1074,10 +1074,6 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry, 
	if (err)

		return err;



	err = fsverity_prepare_setattr(dentry, attr);

	if (err)

		return err;



	if (unlikely(IS_IMMUTABLE(inode)))

		return -EPERM;

fs/verity/open.c

+0 −8
Original line number Diff line number Diff line
@@ -384,14 +384,6 @@ int __fsverity_file_open(struct inode *inode, struct file *filp) 
}

EXPORT_SYMBOL_GPL(__fsverity_file_open);



int __fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr)

{

	if (attr->ia_valid & ATTR_SIZE)

		return -EPERM;

	return 0;

}

EXPORT_SYMBOL_GPL(__fsverity_prepare_setattr);



void __fsverity_cleanup_inode(struct inode *inode)

{

	struct fsverity_info **vi_addr = fsverity_info_addr(inode);

include/linux/fsverity.h

+0 −25
Original line number Diff line number Diff line
@@ -179,7 +179,6 @@ int fsverity_get_digest(struct inode *inode, 
/* open.c */



int __fsverity_file_open(struct inode *inode, struct file *filp);

int __fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr);

void __fsverity_cleanup_inode(struct inode *inode);



/**
@@ -251,12 +250,6 @@ static inline int __fsverity_file_open(struct inode *inode, struct file *filp) 
	return -EOPNOTSUPP;

}



static inline int __fsverity_prepare_setattr(struct dentry *dentry,

					     struct iattr *attr)

{

	return -EOPNOTSUPP;

}



static inline void fsverity_cleanup_inode(struct inode *inode)

{

}
@@ -338,22 +331,4 @@ static inline int fsverity_file_open(struct inode *inode, struct file *filp) 
	return 0;

}



/**

 * fsverity_prepare_setattr() - prepare to change a verity inode's attributes

 * @dentry: dentry through which the inode is being changed

 * @attr: attributes to change

 *

 * Verity files are immutable, so deny truncates.  This isn't covered by the

 * open-time check because sys_truncate() takes a path, not a file descriptor.

 *

 * Return: 0 on success, -errno on failure

 */

static inline int fsverity_prepare_setattr(struct dentry *dentry,

					   struct iattr *attr)

{

	if (IS_VERITY(d_inode(dentry)))

		return __fsverity_prepare_setattr(dentry, attr);

	return 0;

}



#endif	/* _LINUX_FSVERITY_H */