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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [RFC 8/9] x86/nested, xsm: add nested_event_channel_op hypercall
Provides proxying to the host hypervisor for these event channel ops:
* EVTCHNOP_alloc_unbound
* EVTCHNOP_bind_vcpu
* EVTCHNOP_close
* EVTCHNOP_send
* EVTCHNOP_unmask
Introduces a new XSM access vector class for policy control applied to this
operation: nested_event.
This is required because the existing 'event' access vector is unsuitable
for repurposing to the nested case: it operates on per-channel security
identifiers that are generated from a combination of the security
identifiers of the two communicating endpoints and data is not available for
the remote endpoint in the nested case.
Signed-off-by: Christopher Clark <christopher.clark@xxxxxxxxxx>
---
tools/flask/policy/modules/dom0.te | 3 +
xen/arch/x86/guest/hypercall_page.S | 1 +
xen/arch/x86/guest/xen-nested.c | 84 +++++++++++++++++++++++++++
xen/arch/x86/hypercall.c | 1 +
xen/arch/x86/pv/hypercall.c | 1 +
xen/include/public/xen.h | 1 +
xen/include/xen/hypercall.h | 4 ++
xen/include/xsm/dummy.h | 8 +++
xen/include/xsm/xsm.h | 8 +++
xen/xsm/dummy.c | 1 +
xen/xsm/flask/hooks.c | 35 +++++++++++
xen/xsm/flask/policy/access_vectors | 20 +++++++
xen/xsm/flask/policy/security_classes | 1 +
13 files changed, 168 insertions(+)
diff --git a/tools/flask/policy/modules/dom0.te
b/tools/flask/policy/modules/dom0.te
index 03c93a3093..ba3c5ad63d 100644
--- a/tools/flask/policy/modules/dom0.te
+++ b/tools/flask/policy/modules/dom0.te
@@ -48,6 +48,9 @@ allow dom0_t nestedxen_t:version { xen_version
xen_get_features };
allow dom0_t nestedxen_t:mmu physmap;
allow dom0_t nestedxen_t:hvm { setparam getparam };
allow dom0_t nestedxen_t:grant query;
+allow dom0_t nestedxen_t:nested_event {
+ alloc_unbound bind_vcpu close send unmask
+};
# These permissions allow using the FLASK security server to compute access
# checks locally, which could be used by a domain or service (such as xenstore)
diff --git a/xen/arch/x86/guest/hypercall_page.S
b/xen/arch/x86/guest/hypercall_page.S
index 33403714ce..64f1885629 100644
--- a/xen/arch/x86/guest/hypercall_page.S
+++ b/xen/arch/x86/guest/hypercall_page.S
@@ -64,6 +64,7 @@ DECLARE_HYPERCALL(nested_xen_version)
DECLARE_HYPERCALL(nested_memory_op)
DECLARE_HYPERCALL(nested_hvm_op)
DECLARE_HYPERCALL(nested_grant_table_op)
+DECLARE_HYPERCALL(nested_event_channel_op)
DECLARE_HYPERCALL(arch_0)
DECLARE_HYPERCALL(arch_1)
diff --git a/xen/arch/x86/guest/xen-nested.c b/xen/arch/x86/guest/xen-nested.c
index a4049e366f..babf4bf783 100644
--- a/xen/arch/x86/guest/xen-nested.c
+++ b/xen/arch/x86/guest/xen-nested.c
@@ -22,6 +22,7 @@
#include <xen/lib.h>
#include <xen/sched.h>
+#include <public/event_channel.h>
#include <public/grant_table.h>
#include <public/hvm/hvm_op.h>
#include <public/memory.h>
@@ -239,3 +240,86 @@ long do_nested_grant_table_op(unsigned int cmd,
return ret;
}
+
+long do_nested_event_channel_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
+{
+ long ret;
+
+ if ( !xen_nested )
+ return -ENOSYS;
+
+ ret = xsm_nested_event_channel_op(XSM_PRIV, current->domain, cmd);
+ if ( ret )
+ return ret;
+
+ switch ( cmd )
+ {
+ case EVTCHNOP_alloc_unbound:
+ {
+ struct evtchn_alloc_unbound alloc_unbound;
+
+ if ( copy_from_guest(&alloc_unbound, arg, 1) )
+ return -EFAULT;
+
+ ret = xen_hypercall_event_channel_op(cmd, &alloc_unbound);
+ if ( !ret && __copy_to_guest(arg, &alloc_unbound, 1) )
+ {
+ struct evtchn_close close;
+
+ ret = -EFAULT;
+ close.port = alloc_unbound.port;
+
+ if ( xen_hypercall_event_channel_op(EVTCHNOP_close, &close) )
+ gprintk(XENLOG_ERR, "Nested event alloc_unbound failed to
close"
+ " port %u on EFAULT\n",
alloc_unbound.port);
+ }
+ break;
+ }
+
+ case EVTCHNOP_bind_vcpu:
+ {
+ struct evtchn_bind_vcpu bind_vcpu;
+
+ if( copy_from_guest(&bind_vcpu, arg, 1) )
+ return -EFAULT;
+
+ return xen_hypercall_event_channel_op(cmd, &bind_vcpu);
+ }
+
+ case EVTCHNOP_close:
+ {
+ struct evtchn_close close;
+
+ if ( copy_from_guest(&close, arg, 1) )
+ return -EFAULT;
+
+ return xen_hypercall_event_channel_op(cmd, &close);
+ }
+
+ case EVTCHNOP_send:
+ {
+ struct evtchn_send send;
+
+ if ( copy_from_guest(&send, arg, 1) )
+ return -EFAULT;
+
+ return xen_hypercall_event_channel_op(cmd, &send);
+ }
+
+ case EVTCHNOP_unmask:
+ {
+ struct evtchn_unmask unmask;
+
+ if ( copy_from_guest(&unmask, arg, 1) )
+ return -EFAULT;
+
+ return xen_hypercall_event_channel_op(cmd, &unmask);
+ }
+
+ default:
+ gprintk(XENLOG_ERR, "Nested: event hypercall %d not supported.\n",
cmd);
+ return -EOPNOTSUPP;
+ }
+
+ return ret;
+}
diff --git a/xen/arch/x86/hypercall.c b/xen/arch/x86/hypercall.c
index 1b9f4c6050..752955ac81 100644
--- a/xen/arch/x86/hypercall.c
+++ b/xen/arch/x86/hypercall.c
@@ -78,6 +78,7 @@ const hypercall_args_t hypercall_args_table[NR_hypercalls] =
COMP(nested_memory_op, 2, 2),
ARGS(nested_hvm_op, 2),
ARGS(nested_grant_table_op, 3),
+ ARGS(nested_event_channel_op, 2),
#endif
ARGS(mca, 1),
ARGS(arch_1, 1),
diff --git a/xen/arch/x86/pv/hypercall.c b/xen/arch/x86/pv/hypercall.c
index efa1bd0830..6b1ae74d64 100644
--- a/xen/arch/x86/pv/hypercall.c
+++ b/xen/arch/x86/pv/hypercall.c
@@ -89,6 +89,7 @@ const hypercall_table_t pv_hypercall_table[] = {
COMPAT_CALL(nested_memory_op),
HYPERCALL(nested_hvm_op),
HYPERCALL(nested_grant_table_op),
+ HYPERCALL(nested_event_channel_op),
#endif
HYPERCALL(mca),
HYPERCALL(arch_1),
diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
index 000b7fc9d0..5fb322e882 100644
--- a/xen/include/public/xen.h
+++ b/xen/include/public/xen.h
@@ -125,6 +125,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_ulong_t);
#define __HYPERVISOR_nested_memory_op 43
#define __HYPERVISOR_nested_hvm_op 44
#define __HYPERVISOR_nested_grant_table_op 45
+#define __HYPERVISOR_nested_event_channel_op 46
/* Architecture-specific hypercall definitions. */
#define __HYPERVISOR_arch_0 48
diff --git a/xen/include/xen/hypercall.h b/xen/include/xen/hypercall.h
index 102b20fd5f..bd739c2dc7 100644
--- a/xen/include/xen/hypercall.h
+++ b/xen/include/xen/hypercall.h
@@ -167,6 +167,10 @@ extern long do_nested_grant_table_op(
unsigned int cmd,
XEN_GUEST_HANDLE_PARAM(void) uop,
unsigned int count);
+
+extern long do_nested_event_channel_op(
+ int cmd,
+ XEN_GUEST_HANDLE_PARAM(void) arg);
#endif
#ifdef CONFIG_COMPAT
diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h
index f5871ef05a..f8162f3308 100644
--- a/xen/include/xsm/dummy.h
+++ b/xen/include/xsm/dummy.h
@@ -768,6 +768,14 @@ static XSM_INLINE int
xsm_nested_grant_query_size(XSM_DEFAULT_ARG
XSM_ASSERT_ACTION(XSM_PRIV);
return xsm_default_action(action, d, NULL);
}
+
+static XSM_INLINE int xsm_nested_event_channel_op(XSM_DEFAULT_ARG
+ const struct domain *d,
+ unsigned int cmd)
+{
+ XSM_ASSERT_ACTION(XSM_PRIV);
+ return xsm_default_action(action, d, NULL);
+}
#endif
#include <public/version.h>
diff --git a/xen/include/xsm/xsm.h b/xen/include/xsm/xsm.h
index e12001c401..81cb67b89b 100644
--- a/xen/include/xsm/xsm.h
+++ b/xen/include/xsm/xsm.h
@@ -192,6 +192,7 @@ struct xsm_operations {
int (*nested_add_to_physmap) (const struct domain *d);
int (*nested_hvm_op) (const struct domain *d, unsigned int cmd);
int (*nested_grant_query_size) (const struct domain *d);
+ int (*nested_event_channel_op) (const struct domain *d, unsigned int cmd);
#endif
};
@@ -755,6 +756,13 @@ static inline int
xsm_nested_grant_query_size(xsm_default_t def,
return xsm_ops->nested_grant_query_size(d);
}
+static inline int xsm_nested_event_channel_op(xsm_default_t def,
+ const struct domain *d,
+ unsigned int cmd)
+{
+ return xsm_ops->nested_event_channel_op(d, cmd);
+}
+
#endif /* CONFIG_XEN_NESTED */
#endif /* XSM_NO_WRAPPERS */
diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c
index 8c213c258f..91db264ddc 100644
--- a/xen/xsm/dummy.c
+++ b/xen/xsm/dummy.c
@@ -162,5 +162,6 @@ void __init xsm_fixup_ops (struct xsm_operations *ops)
set_to_dummy_if_null(ops, nested_add_to_physmap);
set_to_dummy_if_null(ops, nested_hvm_op);
set_to_dummy_if_null(ops, nested_grant_query_size);
+ set_to_dummy_if_null(ops, nested_event_channel_op);
#endif
}
diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
index 2988df2cd1..27bfa01559 100644
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -1794,6 +1794,40 @@ static int flask_nested_grant_query_size(const struct
domain *d)
return domain_has_nested_perm(d, SECCLASS_GRANT, GRANT__QUERY);
}
+static int flask_nested_event_channel_op(const struct domain *d,
+ unsigned int op)
+{
+ u32 perm;
+
+ switch ( op )
+ {
+ case EVTCHNOP_alloc_unbound:
+ perm = NESTED_EVENT__ALLOC_UNBOUND;
+ break;
+
+ case EVTCHNOP_bind_vcpu:
+ perm = NESTED_EVENT__BIND_VCPU;
+ break;
+
+ case EVTCHNOP_close:
+ perm = NESTED_EVENT__CLOSE;
+ break;
+
+ case EVTCHNOP_send:
+ perm = NESTED_EVENT__SEND;
+ break;
+
+ case EVTCHNOP_unmask:
+ perm = NESTED_EVENT__UNMASK;
+ break;
+
+ default:
+ return avc_unknown_permission("nested event channel op", op);
+ }
+
+ return domain_has_nested_perm(d, SECCLASS_NESTED_EVENT, perm);
+}
+
#endif
long do_flask_op(XEN_GUEST_HANDLE_PARAM(xsm_op_t) u_flask_op);
@@ -1940,6 +1974,7 @@ static struct xsm_operations flask_ops = {
.nested_add_to_physmap = flask_nested_add_to_physmap,
.nested_hvm_op = flask_nested_hvm_op,
.nested_grant_query_size = flask_nested_grant_query_size,
+ .nested_event_channel_op = flask_nested_event_channel_op,
#endif
};
diff --git a/xen/xsm/flask/policy/access_vectors
b/xen/xsm/flask/policy/access_vectors
index 7e0d5aa7bf..87caa36391 100644
--- a/xen/xsm/flask/policy/access_vectors
+++ b/xen/xsm/flask/policy/access_vectors
@@ -316,6 +316,26 @@ class event
reset
}
+# Class nested_event describes event channels to the host hypervisor
+# in a nested Xen-on-Xen system. Policy controls for these differ
+# from the interdomain event channels between guest VMs:
+# the guest hypervisor does not maintain security identifier information about
+# the remote event endpoint managed by the host hypervisor, so nested_event
+# channels do not have their own security label derived from a type transition.
+class nested_event
+{
+ # nested_event_channel_op: EVTCHNOP_alloc_unbound
+ alloc_unbound
+ # nested_event_channel_op: EVTCHNOP_bind_vcpu
+ bind_vcpu
+ # nested_event_channel_op: EVTCHNOP_close
+ close
+ # nested_event_channel_op: EVTCHNOP_send
+ send
+ # nested_event_channel_op: EVTCHNOP_unmask
+ unmask
+}
+
# Class grant describes pages shared by grant mappings. Pages use the security
# label of their owning domain.
class grant
diff --git a/xen/xsm/flask/policy/security_classes
b/xen/xsm/flask/policy/security_classes
index 50ecbabc5c..ce5d00df23 100644
--- a/xen/xsm/flask/policy/security_classes
+++ b/xen/xsm/flask/policy/security_classes
@@ -20,5 +20,6 @@ class grant
class security
class version
class argo
+class nested_event
# FLASK
--
2.17.1
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