Re: [PATCH v4 3/5] xen: add new domctl get_changed_domain

["Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>]

On 12/17/24 06:12, Juergen Gross wrote:
> Add a new domctl sub-function to get data of a domain having changed
> state (this is needed by Xenstore).
>
> The returned state just contains the domid, the domain unique id,
> and some flags (existing, shutdown, dying).
>
> In order to enable Xenstore stubdom being built for multiple Xen
> versions, make this domctl stable.  For stable domctls the
> interface_version is always 0.
>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
> V1:
> - use a domctl subop for the new interface (Jan Beulich)
> V2:
> - fix XSM hooks (Daniel P. Smith)
> - remove versioning of stable sub-ops (Jan Beulich)
> - use domctl.domain for retuning domid of a changed domain (Jan Beulich)
> - simplify locking in get_domain_state() (Jan Beulich)
> - undo stray change in event_channel.c (Jan Beulich)
> V3:
> - have disjunct states "dying" and "dead" (Jan Beulich)
> - check padding fields to be 0 (Jan Beulich)
> - drop memset() (Jan Beulich)
> V4:
> - add locking in get_domain_state() (Jan Beulich)
> - only allow querying domain having changed state by domain receiving
>    VIRQ_DOM_EXC events (Jan Beulich)
> ---
>   tools/flask/policy/modules/dom0.te     |  2 +-
>   tools/flask/policy/modules/xen.if      |  4 +-
>   tools/flask/policy/modules/xenstore.te |  1 +
>   xen/common/domain.c                    | 70 ++++++++++++++++++++++++++
>   xen/common/domctl.c                    | 18 ++++++-
>   xen/common/event_channel.c             |  9 +++-
>   xen/include/public/domctl.h            | 26 ++++++++++
>   xen/include/xen/event.h                |  7 +++
>   xen/include/xen/sched.h                |  2 +
>   xen/include/xsm/dummy.h                |  8 +++
>   xen/include/xsm/xsm.h                  |  6 +++
>   xen/xsm/dummy.c                        |  1 +
>   xen/xsm/flask/hooks.c                  |  7 +++
>   xen/xsm/flask/policy/access_vectors    |  2 +
>   14 files changed, 158 insertions(+), 5 deletions(-)

> diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h
> index f8a3c4b81e..a1a5bb60e9 100644
> --- a/xen/include/xsm/dummy.h
> +++ b/xen/include/xsm/dummy.h
> @@ -173,6 +173,7 @@ static XSM_INLINE int cf_check xsm_domctl(
>       case XEN_DOMCTL_unbind_pt_irq:
>           return xsm_default_action(XSM_DM_PRIV, current->domain, d);
>       case XEN_DOMCTL_getdomaininfo:
> +    case XEN_DOMCTL_get_domain_state:
>           return xsm_default_action(XSM_XS_PRIV, current->domain, d);
>       default:
>           return xsm_default_action(XSM_PRIV, current->domain, d);
> @@ -815,6 +816,13 @@ static XSM_INLINE int cf_check xsm_argo_send(
>   
>   #endif /* CONFIG_ARGO */
>   
> +static XSM_INLINE int cf_check xsm_get_domain_state(
> +    XSM_DEFAULT_ARG struct domain *d)
> +{
> +    XSM_ASSERT_ACTION(XSM_XS_PRIV);
> +    return xsm_default_action(action, current->domain, d);
> +}
> +
>   #include <public/version.h>
>   static XSM_INLINE int cf_check xsm_xen_version(XSM_DEFAULT_ARG uint32_t op)
>   {
> diff --git a/xen/include/xsm/xsm.h b/xen/include/xsm/xsm.h
> index 4dbff9d866..0689bf5c9f 100644
> --- a/xen/include/xsm/xsm.h
> +++ b/xen/include/xsm/xsm.h
> @@ -200,6 +200,7 @@ struct xsm_ops {
>       int (*argo_register_any_source)(const struct domain *d);
>       int (*argo_send)(const struct domain *d, const struct domain *t);
>   #endif
> +    int (*get_domain_state)(struct domain *d);
>   };
>   
>   #ifdef CONFIG_XSM
> @@ -774,6 +775,11 @@ static inline int xsm_argo_send(const struct domain *d, 
> const struct domain *t)
>   
>   #endif /* CONFIG_ARGO */
>   
> +static inline int xsm_get_domain_state(struct domain *d)
> +{
> +    return alternative_call(xsm_ops.get_domain_state, d);
> +}
> +
>   #endif /* XSM_NO_WRAPPERS */
>   
>   #ifdef CONFIG_MULTIBOOT
> diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c
> index e6ffa948f7..ce6fbdc6c5 100644
> --- a/xen/xsm/dummy.c
> +++ b/xen/xsm/dummy.c
> @@ -148,6 +148,7 @@ static const struct xsm_ops __initconst_cf_clobber 
> dummy_ops = {
>       .argo_register_any_source      = xsm_argo_register_any_source,
>       .argo_send                     = xsm_argo_send,
>   #endif
> +    .get_domain_state              = xsm_get_domain_state,
>   };
>   
>   void __init xsm_fixup_ops(struct xsm_ops *ops)
> diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
> index a79474ffe4..e110846ad9 100644
> --- a/xen/xsm/flask/hooks.c
> +++ b/xen/xsm/flask/hooks.c
> @@ -688,6 +688,7 @@ static int cf_check flask_domctl(struct domain *d, unsigned 
> int cmd,
>       case XEN_DOMCTL_memory_mapping:
>       case XEN_DOMCTL_set_target:
>       case XEN_DOMCTL_vm_event_op:
> +    case XEN_DOMCTL_get_domain_state:
>   
>       /* These have individual XSM hooks (arch/../domctl.c) */
>       case XEN_DOMCTL_bind_pt_irq:
> @@ -1856,6 +1857,11 @@ static int cf_check flask_argo_send(
>   
>   #endif
>   
> +static int cf_check flask_get_domain_state(struct domain *d)
> +{
> +    return current_has_perm(d, SECCLASS_DOMAIN2, DOMAIN2__GET_DOMAIN_STATE);
> +}
> +
>   static const struct xsm_ops __initconst_cf_clobber flask_ops = {
>       .set_system_active = flask_set_system_active,
>       .security_domaininfo = flask_security_domaininfo,
> @@ -1992,6 +1998,7 @@ static const struct xsm_ops __initconst_cf_clobber 
> flask_ops = {
>       .argo_register_any_source = flask_argo_register_any_source,
>       .argo_send = flask_argo_send,
>   #endif
> +    .get_domain_state = flask_get_domain_state,
>   };
>   
>   const struct xsm_ops *__init flask_init(
> diff --git a/xen/xsm/flask/policy/access_vectors 
> b/xen/xsm/flask/policy/access_vectors
> index a35e3d4c51..c9a8eeda4e 100644
> --- a/xen/xsm/flask/policy/access_vectors
> +++ b/xen/xsm/flask/policy/access_vectors
> @@ -251,6 +251,8 @@ class domain2
>       resource_map
>   # XEN_DOMCTL_get_cpu_policy
>       get_cpu_policy
> +# XEN_DOMCTL_get_domain_state
> +    get_domain_state
>   }
>   
>   # Similar to class domain, but primarily contains domctls related to HVM domains
Acked-by: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>