On 18/11/2022 11:33, Christian Brauner wrote:

On Fri, Nov 18, 2022 at 11:09:20AM +0100, Mickaël Salaün wrote:

quoted

Hi Christian,

We are working on updating the security_inode_*attr LSM hooks to use path
instead of inode [1]. Indeed, this is required for path-based LSMs such as
Landlock, AppArmor and Tomoyo to make sense of attr/xattr accesses. Could
you please update this new ACL API to use struct path instead of struct
dentry?

Hey Michael,

These patches have been sitting in -next since -rc1 and we are at -rc6
this weekend so this request is too late for the coming merge window. We
can't do a fundamental change this late. I would ask you to please do
these changes in a separate series next cycle. And this will need a
separate discussion among the LSM people and VFS reviews anyway.

Of course, I didn't realize this series was in -next. Please take a look 
at my proposal in the other thread. Thanks.

Thanks!
Christian

quoted

[1]
https://lore.kernel.org/all/1373bbe5-16b1-bf0e-5f92-14c31cb94897@huawei.com/ (local)


On 18/10/2022 13:56, Christian Brauner wrote:

quoted

The current way of setting and getting posix acls through the generic
xattr interface is error prone and type unsafe. The vfs needs to
interpret and fixup posix acls before storing or reporting it to
userspace. Various hacks exist to make this work. The code is hard to
understand and difficult to maintain in it's current form. Instead of
making this work by hacking posix acls through xattr handlers we are
building a dedicated posix acl api around the get and set inode
operations. This removes a lot of hackiness and makes the codepaths
easier to maintain. A lot of background can be found in [1].

Since some filesystem rely on the dentry being available to them when
setting posix acls (e.g., 9p and cifs) they cannot rely on set acl inode
operation. But since ->set_acl() is required in order to use the generic
posix acl xattr handlers filesystems that do not implement this inode
operation cannot use the handler and need to implement their own
dedicated posix acl handlers.

Update the ->set_acl() inode method to take a dentry argument. This
allows all filesystems to rely on ->set_acl().

As far as I can tell all codepaths can be switched to rely on the dentry
instead of just the inode. Note that the original motivation for passing
the dentry separate from the inode instead of just the dentry in the
xattr handlers was because of security modules that call
security_d_instantiate(). This hook is called during
d_instantiate_new(), d_add(), __d_instantiate_anon(), and
d_splice_alias() to initialize the inode's security context and possibly
to set security.* xattrs. Since this only affects security.* xattrs this
is completely irrelevant for posix acls.

Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org (local) [1]
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
---

Notes:
      /* v2 */
      Christoph Hellwig [off-list ref]:
      - Split orangefs into a preparatory patch.
      /* v3 */
      unchanged
      /* v4 */
      unchanged
      /* v5 */
      unchanged

   Documentation/filesystems/vfs.rst |  2 +-
   fs/bad_inode.c                    |  2 +-
   fs/btrfs/acl.c                    |  3 ++-
   fs/btrfs/ctree.h                  |  2 +-
   fs/btrfs/inode.c                  |  2 +-
   fs/ceph/acl.c                     |  3 ++-
   fs/ceph/inode.c                   |  2 +-
   fs/ceph/super.h                   |  2 +-
   fs/ext2/acl.c                     |  3 ++-
   fs/ext2/acl.h                     |  2 +-
   fs/ext2/inode.c                   |  2 +-
   fs/ext4/acl.c                     |  3 ++-
   fs/ext4/acl.h                     |  2 +-
   fs/ext4/inode.c                   |  2 +-
   fs/f2fs/acl.c                     |  4 +++-
   fs/f2fs/acl.h                     |  2 +-
   fs/f2fs/file.c                    |  2 +-
   fs/fuse/acl.c                     |  3 ++-
   fs/fuse/fuse_i.h                  |  2 +-
   fs/gfs2/acl.c                     |  3 ++-
   fs/gfs2/acl.h                     |  2 +-
   fs/gfs2/inode.c                   |  2 +-
   fs/jffs2/acl.c                    |  3 ++-
   fs/jffs2/acl.h                    |  2 +-
   fs/jffs2/fs.c                     |  2 +-
   fs/jfs/acl.c                      |  3 ++-
   fs/jfs/file.c                     |  2 +-
   fs/jfs/jfs_acl.h                  |  2 +-
   fs/ksmbd/smb2pdu.c                |  4 ++--
   fs/ksmbd/smbacl.c                 |  4 ++--
   fs/ksmbd/vfs.c                    | 15 ++++++++-------
   fs/ksmbd/vfs.h                    |  4 ++--
   fs/nfs/nfs3_fs.h                  |  2 +-
   fs/nfs/nfs3acl.c                  |  3 ++-
   fs/nfsd/nfs2acl.c                 |  4 ++--
   fs/nfsd/nfs3acl.c                 |  4 ++--
   fs/nfsd/vfs.c                     |  4 ++--
   fs/ntfs3/file.c                   |  2 +-
   fs/ntfs3/ntfs_fs.h                |  4 ++--
   fs/ntfs3/xattr.c                  |  9 +++++----
   fs/ocfs2/acl.c                    |  3 ++-
   fs/ocfs2/acl.h                    |  2 +-
   fs/orangefs/acl.c                 |  5 +++--
   fs/orangefs/inode.c               |  7 ++++---
   fs/orangefs/orangefs-kernel.h     |  4 ++--
   fs/posix_acl.c                    | 18 +++++++++++-------
   fs/reiserfs/acl.h                 |  6 +++---
   fs/reiserfs/inode.c               |  2 +-
   fs/reiserfs/xattr_acl.c           |  9 ++++++---
   fs/xfs/xfs_acl.c                  |  3 ++-
   fs/xfs/xfs_acl.h                  |  2 +-
   fs/xfs/xfs_iops.c                 | 10 ++++++----
   include/linux/fs.h                |  2 +-
   include/linux/posix_acl.h         | 12 ++++++------
   mm/shmem.c                        |  2 +-
   55 files changed, 119 insertions(+), 93 deletions(-)