Unverified Commit 0e6b7eae authored by Andrey Albershteyn's avatar Andrey Albershteyn Committed by Christian Brauner
Browse files

fs: add FS_XFLAG_VERITY for fs-verity files 



fs-verity introduced inode flag for inodes with enabled fs-verity on
them. This patch adds FS_XFLAG_VERITY file attribute which can be
retrieved with FS_IOC_FSGETXATTR ioctl() and file_getattr() syscall.

This flag is read-only and can not be set with corresponding set ioctl()
and file_setattr(). The FS_IOC_SETFLAGS requires file to be opened for
writing which is not allowed for verity files. The FS_IOC_FSSETXATTR and
file_setattr() clears this flag from the user input.

As this is now common flag for both flag interfaces (flags/xflags) add
it to overlapping flags list to exclude it from overwrite.

Signed-off-by: default avatarAndrey Albershteyn <aalbersh@kernel.org>
Link: https://patch.msgid.link/20260126115658.27656-2-aalbersh@kernel.org


Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 40210c2b

Documentation/filesystems/fsverity.rst

+16 −0
Original line number Diff line number Diff line
@@ -341,6 +341,22 @@ the file has fs-verity enabled. This can perform better than 
FS_IOC_GETFLAGS and FS_IOC_MEASURE_VERITY because it doesn't require

opening the file, and opening verity files can be expensive.



FS_IOC_FSGETXATTR

-----------------



Since Linux v7.0, the FS_IOC_FSGETXATTR ioctl sets FS_XFLAG_VERITY (0x00020000)

in the returned flags when the file has verity enabled. Note that this attribute

cannot be set with FS_IOC_FSSETXATTR as enabling verity requires input

parameters. See FS_IOC_ENABLE_VERITY.



file_getattr

------------



Since Linux v7.0, the file_getattr() syscall sets FS_XFLAG_VERITY (0x00020000)

in the returned flags when the file has verity enabled. Note that this attribute

cannot be set with file_setattr() as enabling verity requires input parameters.

See FS_IOC_ENABLE_VERITY.



.. _accessing_verity_files:



Accessing verity files

fs/file_attr.c

+4 −0
Original line number Diff line number Diff line
@@ -36,6 +36,8 @@ void fileattr_fill_xflags(struct file_kattr *fa, u32 xflags) 
		fa->flags |= FS_DAX_FL;

	if (fa->fsx_xflags & FS_XFLAG_PROJINHERIT)

		fa->flags |= FS_PROJINHERIT_FL;

	if (fa->fsx_xflags & FS_XFLAG_VERITY)

		fa->flags |= FS_VERITY_FL;

}

EXPORT_SYMBOL(fileattr_fill_xflags);
@@ -66,6 +68,8 @@ void fileattr_fill_flags(struct file_kattr *fa, u32 flags) 
		fa->fsx_xflags |= FS_XFLAG_DAX;

	if (fa->flags & FS_PROJINHERIT_FL)

		fa->fsx_xflags |= FS_XFLAG_PROJINHERIT;

	if (fa->flags & FS_VERITY_FL)

		fa->fsx_xflags |= FS_XFLAG_VERITY;

}

EXPORT_SYMBOL(fileattr_fill_flags);

include/linux/fileattr.h

+3 −3
Original line number Diff line number Diff line
@@ -7,16 +7,16 @@ 
#define FS_COMMON_FL \

	(FS_SYNC_FL | FS_IMMUTABLE_FL | FS_APPEND_FL | \

	 FS_NODUMP_FL |	FS_NOATIME_FL | FS_DAX_FL | \

	 FS_PROJINHERIT_FL)

	 FS_PROJINHERIT_FL | FS_VERITY_FL)



#define FS_XFLAG_COMMON \

	(FS_XFLAG_SYNC | FS_XFLAG_IMMUTABLE | FS_XFLAG_APPEND | \

	 FS_XFLAG_NODUMP | FS_XFLAG_NOATIME | FS_XFLAG_DAX | \

	 FS_XFLAG_PROJINHERIT)

	 FS_XFLAG_PROJINHERIT | FS_XFLAG_VERITY)



/* Read-only inode flags */

#define FS_XFLAG_RDONLY_MASK \

	(FS_XFLAG_PREALLOC | FS_XFLAG_HASATTR)

	(FS_XFLAG_PREALLOC | FS_XFLAG_HASATTR | FS_XFLAG_VERITY)



/* Flags to indicate valid value of fsx_ fields */

#define FS_XFLAG_VALUES_MASK \

include/uapi/linux/fs.h

+1 −0
Original line number Diff line number Diff line
@@ -253,6 +253,7 @@ struct file_attr { 
#define FS_XFLAG_FILESTREAM	0x00004000	/* use filestream allocator */

#define FS_XFLAG_DAX		0x00008000	/* use DAX for IO */

#define FS_XFLAG_COWEXTSIZE	0x00010000	/* CoW extent size allocator hint */

#define FS_XFLAG_VERITY		0x00020000	/* fs-verity enabled */

#define FS_XFLAG_HASATTR	0x80000000	/* no DIFLAG for this	*/



/* the read-only stuff doesn't really belong here, but any other place is