| Message ID | 20220420210407.18060-2-dpsmith@apertussolutions.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Adds starting the idle domain privileged | expand |
On Wed, Apr 20, 2022 at 1:02 PM Daniel P. Smith <dpsmith@apertussolutions.com> wrote: > > There are now instances where internal hypervisor logic needs to make resource > allocation calls that are protectd by XSM checks. The internal hypervisor logic > is represented a number of system domains which by designed are represented by > non-privileged struct domain instances. To enable these logic blocks to > function correctly but in a controlled manner, this commit changes the idle > domain to be created as a privileged domain under the default policy, which is > inherited by the SILO policy, and demoted before transitioning to running. A > new XSM hook, xsm_transition_running, is introduced to allow each XSM policy > type to demote the idle domain appropriately for that policy type. > > For flask a stub is added to ensure that flask policy system will function > correctly with this patch until flask is extended with support for starting the > idle domain privileged and properly demoting it on the call to > xsm_transtion_running. > > Signed-off-by: Daniel P. Smith <dpsmith@apertussolutions.com> > --- > diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c > index 6f20e17892..72695dcb07 100644 > --- a/xen/arch/x86/setup.c > +++ b/xen/arch/x86/setup.c > @@ -621,6 +621,12 @@ static void noreturn init_done(void) > void *va; > unsigned long start, end; > > + xsm_transition_running(); > + > + /* Ensure idle domain was not left privileged */ > + if ( current->domain->is_privileged ) > + panic("idle domain did not properly transition from setup privilege\n"); Checking immediately after the XSM hook seems redundant, though I guess having a sanity check isn't harmful. > static void cf_check flask_domain_free_security(struct domain *d) > { > struct domain_security_struct *dsec = d->ssid; > @@ -1766,6 +1780,7 @@ static int cf_check flask_argo_send( > #endif > > static const struct xsm_ops __initconst_cf_clobber flask_ops = { > + .transition_running = flask_domain_runtime_security, I'd prefer flask_transition_running. That way grep for the hook name also finds the flask implementation. Regards, Jason
On 4/20/22 14:31, Jason Andryuk wrote: > On Wed, Apr 20, 2022 at 1:02 PM Daniel P. Smith > <dpsmith@apertussolutions.com> wrote: >> >> There are now instances where internal hypervisor logic needs to make resource >> allocation calls that are protectd by XSM checks. The internal hypervisor logic >> is represented a number of system domains which by designed are represented by >> non-privileged struct domain instances. To enable these logic blocks to >> function correctly but in a controlled manner, this commit changes the idle >> domain to be created as a privileged domain under the default policy, which is >> inherited by the SILO policy, and demoted before transitioning to running. A >> new XSM hook, xsm_transition_running, is introduced to allow each XSM policy >> type to demote the idle domain appropriately for that policy type. >> >> For flask a stub is added to ensure that flask policy system will function >> correctly with this patch until flask is extended with support for starting the >> idle domain privileged and properly demoting it on the call to >> xsm_transtion_running. >> >> Signed-off-by: Daniel P. Smith <dpsmith@apertussolutions.com> >> --- > >> diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c >> index 6f20e17892..72695dcb07 100644 >> --- a/xen/arch/x86/setup.c >> +++ b/xen/arch/x86/setup.c >> @@ -621,6 +621,12 @@ static void noreturn init_done(void) >> void *va; >> unsigned long start, end; >> >> + xsm_transition_running(); >> + >> + /* Ensure idle domain was not left privileged */ >> + if ( current->domain->is_privileged ) >> + panic("idle domain did not properly transition from setup privilege\n"); > > Checking immediately after the XSM hook seems redundant, though I > guess having a sanity check isn't harmful. I was back and forth on this, so I threw it in and figured if there was strong opinions against it I could easily remove and respin the series. >> static void cf_check flask_domain_free_security(struct domain *d) >> { >> struct domain_security_struct *dsec = d->ssid; >> @@ -1766,6 +1780,7 @@ static int cf_check flask_argo_send( >> #endif >> >> static const struct xsm_ops __initconst_cf_clobber flask_ops = { >> + .transition_running = flask_domain_runtime_security, > > I'd prefer flask_transition_running. That way grep for the hook name > also finds the flask implementation. Sure. v/r, dps
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c index d5d0792ed4..763835aeb5 100644 --- a/xen/arch/arm/setup.c +++ b/xen/arch/arm/setup.c @@ -1048,6 +1048,12 @@ void __init start_xen(unsigned long boot_phys_offset, /* Hide UART from DOM0 if we're using it */ serial_endboot(); + xsm_transition_running(); + + /* Ensure idle domain was not left privileged */ + if ( current->domain->is_privileged ) + panic("idle domain did not properly transition from setup privilege\n"); + system_state = SYS_STATE_active; for_each_domain( d ) diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c index 6f20e17892..72695dcb07 100644 --- a/xen/arch/x86/setup.c +++ b/xen/arch/x86/setup.c @@ -621,6 +621,12 @@ static void noreturn init_done(void) void *va; unsigned long start, end; + xsm_transition_running(); + + /* Ensure idle domain was not left privileged */ + if ( current->domain->is_privileged ) + panic("idle domain did not properly transition from setup privilege\n"); + system_state = SYS_STATE_active; domain_unpause_by_systemcontroller(dom0); diff --git a/xen/common/sched/core.c b/xen/common/sched/core.c index 19ab678181..22a619e260 100644 --- a/xen/common/sched/core.c +++ b/xen/common/sched/core.c @@ -3021,7 +3021,12 @@ void __init scheduler_init(void) sched_ratelimit_us = SCHED_DEFAULT_RATELIMIT_US; } - idle_domain = domain_create(DOMID_IDLE, NULL, 0); + /* + * idle dom is created privileged to ensure unrestricted access during + * setup and will be demoted by xsm_transition_running when setup is + * complete + */ + idle_domain = domain_create(DOMID_IDLE, NULL, CDF_privileged); BUG_ON(IS_ERR(idle_domain)); BUG_ON(nr_cpu_ids > ARRAY_SIZE(idle_vcpu)); idle_domain->vcpu = idle_vcpu; diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h index 58afc1d589..b33f0ec672 100644 --- a/xen/include/xsm/dummy.h +++ b/xen/include/xsm/dummy.h @@ -101,6 +101,18 @@ static always_inline int xsm_default_action( } } +static XSM_INLINE void cf_check xsm_transition_running(void) +{ + struct domain *d = current->domain; + + if ( d->domain_id != DOMID_IDLE ) + panic("xsm_transition_running should only be called by idle domain\n"); + + d->is_privileged = false; + + return; +} + static XSM_INLINE void cf_check xsm_security_domaininfo( struct domain *d, struct xen_domctl_getdomaininfo *info) { diff --git a/xen/include/xsm/xsm.h b/xen/include/xsm/xsm.h index 3e2b7fe3db..a5c06804ab 100644 --- a/xen/include/xsm/xsm.h +++ b/xen/include/xsm/xsm.h @@ -52,6 +52,7 @@ typedef enum xsm_default xsm_default_t; * !!! WARNING !!! */ struct xsm_ops { + void (*transition_running)(void); void (*security_domaininfo)(struct domain *d, struct xen_domctl_getdomaininfo *info); int (*domain_create)(struct domain *d, uint32_t ssidref); @@ -208,6 +209,11 @@ extern struct xsm_ops xsm_ops; #ifndef XSM_NO_WRAPPERS +static inline void xsm_transition_running(void) +{ + alternative_vcall(xsm_ops.transition_running); +} + static inline void xsm_security_domaininfo( struct domain *d, struct xen_domctl_getdomaininfo *info) { diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c index 8c044ef615..66f26c6909 100644 --- a/xen/xsm/dummy.c +++ b/xen/xsm/dummy.c @@ -14,6 +14,7 @@ #include <xsm/dummy.h> static const struct xsm_ops __initconst_cf_clobber dummy_ops = { + .transition_running = xsm_transition_running, .security_domaininfo = xsm_security_domaininfo, .domain_create = xsm_domain_create, .getdomaininfo = xsm_getdomaininfo, diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c index 0bf63ffa84..51c896d9f7 100644 --- a/xen/xsm/flask/hooks.c +++ b/xen/xsm/flask/hooks.c @@ -186,6 +186,20 @@ static int cf_check flask_domain_alloc_security(struct domain *d) return 0; } +static void cf_check flask_domain_runtime_security(void) +{ + struct domain *d = current->domain; + + if ( d->domain_id != DOMID_IDLE ) + panic("xsm_transition_running should only be called by idle domain\n"); + + /* + * While is_privileged has no significant meaning under flask, + * set to false for the consistency check(s) in the setup code. + */ + d->is_privileged = false; +} + static void cf_check flask_domain_free_security(struct domain *d) { struct domain_security_struct *dsec = d->ssid; @@ -1766,6 +1780,7 @@ static int cf_check flask_argo_send( #endif static const struct xsm_ops __initconst_cf_clobber flask_ops = { + .transition_running = flask_domain_runtime_security, .security_domaininfo = flask_security_domaininfo, .domain_create = flask_domain_create, .getdomaininfo = flask_getdomaininfo,
There are now instances where internal hypervisor logic needs to make resource allocation calls that are protectd by XSM checks. The internal hypervisor logic is represented a number of system domains which by designed are represented by non-privileged struct domain instances. To enable these logic blocks to function correctly but in a controlled manner, this commit changes the idle domain to be created as a privileged domain under the default policy, which is inherited by the SILO policy, and demoted before transitioning to running. A new XSM hook, xsm_transition_running, is introduced to allow each XSM policy type to demote the idle domain appropriately for that policy type. For flask a stub is added to ensure that flask policy system will function correctly with this patch until flask is extended with support for starting the idle domain privileged and properly demoting it on the call to xsm_transtion_running. Signed-off-by: Daniel P. Smith <dpsmith@apertussolutions.com> --- xen/arch/arm/setup.c | 6 ++++++ xen/arch/x86/setup.c | 6 ++++++ xen/common/sched/core.c | 7 ++++++- xen/include/xsm/dummy.h | 12 ++++++++++++ xen/include/xsm/xsm.h | 6 ++++++ xen/xsm/dummy.c | 1 + xen/xsm/flask/hooks.c | 15 +++++++++++++++ 7 files changed, 52 insertions(+), 1 deletion(-)