Re: [PATCH v2] security: Return xattr name from security_dentry_init_security()

On Tue, Oct 12, 2021 at 9:23 AM Vivek Goyal [off-list ref] wrote:

Right now security_dentry_init_security() only supports single security
label and is used by SELinux only. There are two users of of this hook,
namely ceph and nfs.

NFS does not care about xattr name. Ceph hardcodes the xattr name to
security.selinux (XATTR_NAME_SELINUX).

I am making changes to fuse/virtiofs to send security label to virtiofsd
and I need to send xattr name as well. I also hardcoded the name of
xattr to security.selinux.

Stephen Smalley suggested that it probably is a good idea to modify
security_dentry_init_security() to also return name of xattr so that
we can avoid this hardcoding in the callers.

This patch adds a new parameter "const char **xattr_name" to
security_dentry_init_security() and LSM puts the name of xattr
too if caller asked for it (xattr_name != NULL).

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
---

Changes since v1:
- Updated comment to make it clear caller does not have to free the
  xattr_name. (Jeff Layton).
- Captured Jeff's Reviewed-by ack.

I have tested this patch with virtiofs and compile tested for ceph and nfs.

NFS changes are trivial. Looking for an ack from NFS maintainers.

---
 fs/ceph/xattr.c               |    3 +--
 fs/nfs/nfs4proc.c             |    3 ++-
 include/linux/lsm_hook_defs.h |    3 ++-
 include/linux/lsm_hooks.h     |    3 +++
 include/linux/security.h      |    6 ++++--
 security/security.c           |    7 ++++---
 security/selinux/hooks.c      |    6 +++++-
 7 files changed, 21 insertions(+), 10 deletions(-)

This looks fine to me and considering the trivial nature of the NFS
changes I'm okay with merging this without an explicit ACK from the
NFS folks.  Similarly, I generally dislike merging new functionality
once we hit -rc6, but this is trivial enough that I think it's okay;
I'm merging this into selinux/next now, thanks everyone.

-- 
paul moore
www.paul-moore.com