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

[Paul Moore]

On Tue, Oct 12, 2021 at 9:23 AM Vivek Goyal <vgoyal at redhat.com> 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 at redhat.com>
> Reviewed-by: Jeff Layton <jlayton at 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