Unverified Commit 276e136b authored by Amir Goldstein's avatar Amir Goldstein Committed by Christian Brauner
Browse files

fs: prepare for extending file_get/setattr() 

We intend to add support for more xflags to selective filesystems and
We cannot rely on copy_struct_from_user() to detect this extension.

In preparation of extending the API, do not allow setting xflags unknown
by this kernel version.

Also do not pass the read-only flags and read-only field fsx_nextents to
filesystem.

These changes should not affect existing chattr programs that use the
ioctl to get fsxattr before setting the new values.

Link: https://lore.kernel.org/linux-fsdevel/20250216164029.20673-4-pali@kernel.org/


Cc: Pali Rohár <pali@kernel.org>
Cc: Andrey Albershteyn <aalbersh@redhat.com>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarAndrey Albershteyn <aalbersh@kernel.org>
Link: https://lore.kernel.org/20250630-xattrat-syscall-v6-5-c4e3bc35227b@kernel.org


Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 474b155a

fs/file_attr.c

+7 −1
Original line number Diff line number Diff line
@@ -100,9 +100,10 @@ EXPORT_SYMBOL(vfs_fileattr_get); 
int copy_fsxattr_to_user(const struct fileattr *fa, struct fsxattr __user *ufa)

{

	struct fsxattr xfa;

	__u32 mask = FS_XFLAGS_MASK;



	memset(&xfa, 0, sizeof(xfa));

	xfa.fsx_xflags = fa->fsx_xflags;

	xfa.fsx_xflags = fa->fsx_xflags & mask;

	xfa.fsx_extsize = fa->fsx_extsize;

	xfa.fsx_nextents = fa->fsx_nextents;

	xfa.fsx_projid = fa->fsx_projid;
@@ -119,11 +120,16 @@ static int copy_fsxattr_from_user(struct fileattr *fa, 
				  struct fsxattr __user *ufa)

{

	struct fsxattr xfa;

	__u32 mask = FS_XFLAGS_MASK;



	if (copy_from_user(&xfa, ufa, sizeof(xfa)))

		return -EFAULT;



	if (xfa.fsx_xflags & ~mask)

		return -EOPNOTSUPP;



	fileattr_fill_xflags(fa, xfa.fsx_xflags);

	fa->fsx_xflags &= ~FS_XFLAG_RDONLY_MASK;

	fa->fsx_extsize = xfa.fsx_extsize;

	fa->fsx_nextents = xfa.fsx_nextents;

	fa->fsx_projid = xfa.fsx_projid;

include/linux/fileattr.h

+20 −0
Original line number Diff line number Diff line
@@ -14,6 +14,26 @@ 
	 FS_XFLAG_NODUMP | FS_XFLAG_NOATIME | FS_XFLAG_DAX | \

	 FS_XFLAG_PROJINHERIT)



/* Read-only inode flags */

#define FS_XFLAG_RDONLY_MASK \

	(FS_XFLAG_PREALLOC | FS_XFLAG_HASATTR)



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

#define FS_XFLAG_VALUES_MASK \

	(FS_XFLAG_EXTSIZE | FS_XFLAG_COWEXTSIZE)



/* Flags for directories */

#define FS_XFLAG_DIRONLY_MASK \

	(FS_XFLAG_RTINHERIT | FS_XFLAG_NOSYMLINKS | FS_XFLAG_EXTSZINHERIT)



/* Misc settable flags */

#define FS_XFLAG_MISC_MASK \

	(FS_XFLAG_REALTIME | FS_XFLAG_NODEFRAG | FS_XFLAG_FILESTREAM)



#define FS_XFLAGS_MASK \

	(FS_XFLAG_COMMON | FS_XFLAG_RDONLY_MASK | FS_XFLAG_VALUES_MASK | \

	 FS_XFLAG_DIRONLY_MASK | FS_XFLAG_MISC_MASK)



/*

 * Merged interface for miscellaneous file attributes.  'flags' originates from

 * ext* and 'fsx_flags' from xfs.  There's some overlap between the two, which