[Xen-devel] [PATCH 07/17] flask: unify {get, set}vcpucontext permissions
These permissions were initially split because they were in separate
domctls, but this split is very unlikely to actually provide security
benefits: it would require a carefully contrived situation for a domain
to both need access to one type of CPU register and also need to be
prohibited from accessing another type.
Signed-off-by: Daniel De Graaf
Reviewed-by: Konrad Rzeszutek Wilk
---
tools/flask/policy/modules/dom0.te | 1 -
tools/flask/policy/modules/xen.if | 7 +++
xen/xsm/flask/hooks.c | 20 ++--
xen/xsm/flask/policy/access_vectors | 16 ++--
4 files changed, 15 insertions(+), 29 deletions(-)
diff --git a/tools/flask/policy/modules/dom0.te
b/tools/flask/policy/modules/dom0.te
index ef6a986..d228b24 100644
--- a/tools/flask/policy/modules/dom0.te
+++ b/tools/flask/policy/modules/dom0.te
@@ -34,7 +34,6 @@ allow dom0_t dom0_t:domain {
setvcpucontext max_vcpus setaffinity getaffinity getscheduler
getdomaininfo getvcpuinfo getvcpucontext setdomainmaxmem setdomainhandle
setdebugging hypercall settime setaddrsize getaddrsize trigger
- getextvcpucontext setextvcpucontext getvcpuextstate setvcpuextstate
getpodtarget setpodtarget set_misc_info set_virq_handler
};
allow dom0_t dom0_t:domain2 {
diff --git a/tools/flask/policy/modules/xen.if
b/tools/flask/policy/modules/xen.if
index 00d1bbb..fd96303 100644
--- a/tools/flask/policy/modules/xen.if
+++ b/tools/flask/policy/modules/xen.if
@@ -47,9 +47,8 @@ define(`declare_build_label', `
define(`create_domain_common', `
allow $1 $2:domain { create max_vcpus setdomainmaxmem setaddrsize
- getdomaininfo hypercall setvcpucontext setextvcpucontext
- getscheduler getvcpuinfo getvcpuextstate getaddrsize
- getaffinity setaffinity setvcpuextstate };
+ getdomaininfo hypercall setvcpucontext getscheduler
+ getvcpuinfo getaddrsize getaffinity setaffinity };
allow $1 $2:domain2 { set_cpuid settsc setscheduler setclaim
set_max_evtchn set_vnumainfo get_vnumainfo cacheflush
psr_cmt_op psr_cat_op soft_reset };
@@ -94,7 +93,7 @@ define(`migrate_domain_out', `
allow $1 domxen_t:mmu map_read;
allow $1 $2:hvm { gethvmc getparam irqlevel };
allow $1 $2:mmu { stat pageinfo map_read };
- allow $1 $2:domain { getaddrsize getvcpucontext getextvcpucontext
getvcpuextstate pause destroy };
+ allow $1 $2:domain { getaddrsize getvcpucontext pause destroy };
allow $1 $2:domain2 gettsc;
allow $1 $2:shadow { enable disable logdirty };
')
diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
index 20d46c8..a8d45e7 100644
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -630,10 +630,16 @@ static int flask_domctl(struct domain *d, int cmd)
case XEN_DOMCTL_setdomainhandle:
return current_has_perm(d, SECCLASS_DOMAIN, DOMAIN__SETDOMAINHANDLE);
+case XEN_DOMCTL_set_ext_vcpucontext:
+case XEN_DOMCTL_set_vcpu_msrs:
case XEN_DOMCTL_setvcpucontext:
+case XEN_DOMCTL_setvcpuextstate:
return current_has_perm(d, SECCLASS_DOMAIN, DOMAIN__SETVCPUCONTEXT);
+case XEN_DOMCTL_get_ext_vcpucontext:
+case XEN_DOMCTL_get_vcpu_msrs:
case XEN_DOMCTL_getvcpucontext:
+case XEN_DOMCTL_getvcpuextstate:
return current_has_perm(d, SECCLASS_DOMAIN, DOMAIN__GETVCPUCONTEXT);
case XEN_DOMCTL_getvcpuinfo:
@@ -675,20 +681,6 @@ static int flask_domctl(struct domain *d, int cmd)
case XEN_DOMCTL_pin_mem_cacheattr:
return current_has_perm(d, SECCLASS_HVM, HVM__CACHEATTR);
-case XEN_DOMCTL_set_ext_vcpucontext:
-case XEN_DOMCTL_set_vcpu_msrs:
-return current_has_perm(d, SECCLASS_DOMAIN, DOMAIN__SETEXTVCPUCONTEXT);
-
-case XEN_DOMCTL_get_ext_vcpucontext:
-case XEN_DOMCTL_get_vcpu_msrs:
-return current_has_perm(d, SECCLASS_DOMAIN, DOMAIN__GETEXTVCPUCONTEXT);
-
-case XEN_DOMCTL_setvcpuextstate:
-return current_has_perm(d, SECCLASS_DOMAIN, DOMAIN__SETVCPUEXTSTATE);
-
-case XEN_DOMCTL_getvcpuextstate:
-return current_has_perm(d, SECCLASS_DOMAIN, DOMAIN__GETVCPUEXTSTATE);
-
case XEN_DOMCTL_sendtrigger:
return current_has_perm(d, SECCLASS_DOMAIN, DOMAIN__TRIGGER);
diff --git a/xen/xsm/flask/policy/access_vectors
b/xen/xsm/flask/policy/access_vectors
index 3d29042..7e69ede 100644
--- a/xen/xsm/flask/policy/access_vectors
+++ b/xen/xsm/flask/policy/access_vectors
@@ -111,6 +111,9 @@ class xen2
class domain
{
# XEN_DOMCTL_setvcpucontext
+# XEN_DOMCTL_setvcpuextstate
+# XEN_DOMCTL_set_ext_vcpucontext
+# XEN_DOMCTL_set_vcpu_msrs
setvcpucontext
# XEN_DOMCTL_pausedomain
pause
@@ -142,6 +145,9 @@ class domain
# XEN_DOMCTL_getvcpuinfo
getvcpuinfo
# XEN_DOMCTL_getvcpucontext
+# XEN_DOMCTL_get_ext_vcpucontext
+# XEN_DOMCTL_getvcpuextstate
+#
Re: [Xen-devel] [PATCH 07/17] flask: unify {get, set}vcpucontext permissions
On 6/20/16 9:04 AM, Daniel De Graaf wrote: > These permissions were initially split because they were in separate > domctls, but this split is very unlikely to actually provide security > benefits: it would require a carefully contrived situation for a domain > to both need access to one type of CPU register and also need to be > prohibited from accessing another type. > > Signed-off-by: Daniel De Graaf > Reviewed-by: Konrad Rzeszutek Wilk I'm a: Reviewed-by: Doug Goldstein But I'd like to see Andrew Cooper's R-b or comments as well. -- Doug Goldstein signature.asc Description: OpenPGP digital signature ___ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
Re: [Xen-devel] [PATCH 07/17] flask: unify {get, set}vcpucontext permissions
On 20/06/16 15:27, Doug Goldstein wrote: > On 6/20/16 9:04 AM, Daniel De Graaf wrote: >> These permissions were initially split because they were in separate >> domctls, but this split is very unlikely to actually provide security >> benefits: it would require a carefully contrived situation for a domain >> to both need access to one type of CPU register and also need to be >> prohibited from accessing another type. >> >> Signed-off-by: Daniel De Graaf >> Reviewed-by: Konrad Rzeszutek Wilk > I'm a: > > Reviewed-by: Doug Goldstein > > But I'd like to see Andrew Cooper's R-b or comments as well. > I agree. I can't see a plausible usecase for an entity being entitled to read vcpu content, but not to modify it. Reviewed-by: Andrew Cooper ___ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
Re: [Xen-devel] [PATCH 07/17] flask: unify {get, set}vcpucontext permissions
On 06/20/2016 10:35 AM, Andrew Cooper wrote: On 20/06/16 15:27, Doug Goldstein wrote: On 6/20/16 9:04 AM, Daniel De Graaf wrote: These permissions were initially split because they were in separate domctls, but this split is very unlikely to actually provide security benefits: it would require a carefully contrived situation for a domain to both need access to one type of CPU register and also need to be prohibited from accessing another type. Signed-off-by: Daniel De Graaf Reviewed-by: Konrad Rzeszutek Wilk I'm a: Reviewed-by: Doug Goldstein But I'd like to see Andrew Cooper's R-b or comments as well. I agree. I can't see a plausible usecase for an entity being entitled to read vcpu content, but not to modify it. Reviewed-by: Andrew Cooper That's not exactly what this patch does: the get and set permissions are still split, but unified across the different types of registers. Where previously there were 6 permissions, now there are 2. A use case where you would be entitled to read but not modify is a monitoring domain (remote virus scanner, for example) which needs read access to scan but does not do remediation itself. -- Daniel De Graaf National Security Agency ___ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
Re: [Xen-devel] [PATCH 07/17] flask: unify {get, set}vcpucontext permissions
On 20/06/16 15:50, Daniel De Graaf wrote: > On 06/20/2016 10:35 AM, Andrew Cooper wrote: >> On 20/06/16 15:27, Doug Goldstein wrote: >>> On 6/20/16 9:04 AM, Daniel De Graaf wrote: These permissions were initially split because they were in separate domctls, but this split is very unlikely to actually provide security benefits: it would require a carefully contrived situation for a domain to both need access to one type of CPU register and also need to be prohibited from accessing another type. Signed-off-by: Daniel De Graaf Reviewed-by: Konrad Rzeszutek Wilk >>> I'm a: >>> >>> Reviewed-by: Doug Goldstein >>> >>> But I'd like to see Andrew Cooper's R-b or comments as well. >>> >> >> I agree. I can't see a plausible usecase for an entity being entitled >> to read vcpu content, but not to modify it. >> >> Reviewed-by: Andrew Cooper > > That's not exactly what this patch does: the get and set permissions > are still split, but unified across the different types of registers. > Where previously there were 6 permissions, now there are 2. The boundaries for those hypercalls were somewhat arbitrary, and definitely awkward to use. Some information is duplicated between them. I plan to make them all disappear, in favour of something more consistent when altering the migration stream semantics. ~Andrew ___ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
