On 2021-05-10 18:48, Paul Moore wrote:
On Sun, May 9, 2021 at 2:33 PM Michael Weiß
<michael.weiss(a)aisec.fraunhofer.de> wrote:
>
> Audit subsystem was disabled in total for user namespaces other than
> the initial namespace.
>
> If audit is enabled by kernel command line or audtid in initial namespace,
> it is now possible to allow at least logging of userspace applications
> inside of non-initial namespaces if CAP_AUDIT_WRITE in the corresponding
> namespace is held.
>
> This allows logging of, e.g., PAM or opensshd inside user namespaced
> system containers.
>
> Signed-off-by: Michael Weiß <michael.weiss(a)aisec.fraunhofer.de>
> ---
> kernel/audit.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
I think this needs to wait on the audit container ID patchset to land.
That will interact with this, for sure and others related.
Given that there are non-init namespaces involved that may not be part
of containers, I would prefer to wait until namespaces are also
optionally documentable in audit events before permitting this change.
A patchset exists, but it has been deferred until the audit container
identifier patchset is settled.
(See
https://github.com/linux-audit/audit-kernel/issues/32 )
> diff --git a/kernel/audit.c b/kernel/audit.c
> index 121d37e700a6..b5cc0669c3d7 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -1012,7 +1012,13 @@ static int audit_netlink_ok(struct sk_buff *skb, u16
msg_type)
> * userspace will reject all logins. This should be removed when we
> * support non init namespaces!!
> */
> - if (current_user_ns() != &init_user_ns)
> + /*
> + * If audit is enabled by kernel command line or audtid in the initial
> + * namespace allow at least logging of userspace applications inside of
> + * non-initial namespaces according to CAP_AUDIT_WRITE is held in the
> + * corresponding namespace.
> + */
> + if ((current_user_ns() != &init_user_ns) && !audit_enabled)
> return -ECONNREFUSED;
>
> switch (msg_type) {
> @@ -1043,7 +1049,7 @@ static int audit_netlink_ok(struct sk_buff *skb, u16
msg_type)
> case AUDIT_USER:
> case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
> case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
> - if (!netlink_capable(skb, CAP_AUDIT_WRITE))
> + if (!netlink_ns_capable(skb, current_user_ns(), CAP_AUDIT_WRITE))
> err = -EPERM;
> break;
> default: /* bad msg */
> --
> 2.20.1
--
paul moore
www.paul-moore.com
- RGB
--
Richard Guy Briggs <rgb(a)redhat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635