[PATCH v3 11/15] xsm, argo: XSM control for argo register

[Christopher Clark <christopher.w.clark@gmail.com>]

XSM controls for argo ring registration with two distinct cases, where
the ring being registered is:

1) Single source:  registering a ring for communication to receive messages
                   from a specified single other domain.
   Default policy: allow.

2) Any source:     registering a ring for communication to receive messages
                   from any, or all, other domains (ie. wildcard).
   Default policy: deny, with runtime policy configuration via bootparam.

The existing argo-mac boot parameter indicates administrator preference for
either permissive or strict access control, which will allow or deny
registration of any-sender rings.

This commit modifies the signature of core XSM hook functions in order to
apply 'const' to arguments, needed in order for 'const' to be accepted in
signature of functions that invoke them.

Signed-off-by: Christopher Clark <christopher.clark6@baesystems.com>
---
v2 feedback #9 Jan: refactor to use argo-mac bootparam at point of introduction
v1 feedback Paul: replace use of strncmp with strcmp
v1 feedback #16 Jan: apply const to function signatures
v1 feedback #14 Jan: add blank line before return in parse_argo_mac_param

 xen/common/argo.c                     | 14 ++++++++++----
 xen/include/xsm/dummy.h               | 15 +++++++++++++++
 xen/include/xsm/xsm.h                 | 19 +++++++++++++++++++
 xen/xsm/dummy.c                       |  4 ++++
 xen/xsm/flask/hooks.c                 | 27 ++++++++++++++++++++++++---
 xen/xsm/flask/policy/access_vectors   | 11 +++++++++++
 xen/xsm/flask/policy/security_classes |  1 +
 7 files changed, 84 insertions(+), 7 deletions(-)

diff --git a/xen/common/argo.c b/xen/common/argo.c
index 37eb291..1674f18 100644
--- a/xen/common/argo.c
+++ b/xen/common/argo.c
@@ -26,6 +26,7 @@
 #include <xen/lib.h>
 #include <xen/nospec.h>
 #include <xen/time.h>
+#include <xsm/xsm.h>
 #include <public/argo.h>
 
 #define MAX_RINGS_PER_DOMAIN            128U
@@ -1582,11 +1583,9 @@ register_ring(struct domain *currd,
 
     if ( reg.partner_id == XEN_ARGO_DOMID_ANY )
     {
-        if ( opt_argo_mac_enforcing )
-        {
-            ret = -EPERM;
+        ret = xsm_argo_register_any_source(currd, opt_argo_mac_enforcing);
+        if ( ret )
             goto out_unlock;
-        }
     }
     else
     {
@@ -1598,6 +1597,13 @@ register_ring(struct domain *currd,
             goto out_unlock;
         }
 
+        ret = xsm_argo_register_single_source(currd, dst_d);
+        if ( ret )
+        {
+            put_domain(dst_d);
+            goto out_unlock;
+        }
+
         if ( !dst_d->argo )
         {
             argo_dprintk("!dst_d->argo, ECONNREFUSED\n");
diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h
index a29d1ef..55113c3 100644
--- a/xen/include/xsm/dummy.h
+++ b/xen/include/xsm/dummy.h
@@ -720,6 +720,21 @@ static XSM_INLINE int xsm_dm_op(XSM_DEFAULT_ARG struct domain *d)
 
 #endif /* CONFIG_X86 */
 
+#ifdef CONFIG_ARGO
+static XSM_INLINE int xsm_argo_register_single_source(struct domain *d,
+                                                      struct domain *t)
+{
+    return 0;
+}
+
+static XSM_INLINE int xsm_argo_register_any_source(struct domain *d,
+                                                   bool strict)
+{
+    return strict ? -EPERM : 0;
+}
+
+#endif /* CONFIG_ARGO */
+
 #include <public/version.h>
 static XSM_INLINE int xsm_xen_version (XSM_DEFAULT_ARG uint32_t op)
 {
diff --git a/xen/include/xsm/xsm.h b/xen/include/xsm/xsm.h
index 3b192b5..e775a6d 100644
--- a/xen/include/xsm/xsm.h
+++ b/xen/include/xsm/xsm.h
@@ -181,6 +181,11 @@ struct xsm_operations {
 #endif
     int (*xen_version) (uint32_t cmd);
     int (*domain_resource_map) (struct domain *d);
+#ifdef CONFIG_ARGO
+    int (*argo_register_single_source) (const struct domain *d,
+                                        const struct domain *t);
+    int (*argo_register_any_source) (const struct domain *d);
+#endif
 };
 
 #ifdef CONFIG_XSM
@@ -698,6 +703,20 @@ static inline int xsm_domain_resource_map(xsm_default_t def, struct domain *d)
     return xsm_ops->domain_resource_map(d);
 }
 
+#ifdef CONFIG_ARGO
+static inline xsm_argo_register_single_source(const struct domain *d,
+                                              const struct domain *t)
+{
+    return xsm_ops->argo_register_single_source(d, t);
+}
+
+static inline xsm_argo_register_any_source(const struct domain *d, bool strict)
+{
+    return xsm_ops->argo_register_any_source(d);
+}
+
+#endif /* CONFIG_ARGO */
+
 #endif /* XSM_NO_WRAPPERS */
 
 #ifdef CONFIG_MULTIBOOT
diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c
index 5701047..ed236b0 100644
--- a/xen/xsm/dummy.c
+++ b/xen/xsm/dummy.c
@@ -152,4 +152,8 @@ void __init xsm_fixup_ops (struct xsm_operations *ops)
 #endif
     set_to_dummy_if_null(ops, xen_version);
     set_to_dummy_if_null(ops, domain_resource_map);
+#ifdef CONFIG_ARGO
+    set_to_dummy_if_null(ops, argo_register_single_source);
+    set_to_dummy_if_null(ops, argo_register_any_source);
+#endif
 }
diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
index 96d31aa..fcb7487 100644
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -36,13 +36,14 @@
 #include <objsec.h>
 #include <conditional.h>
 
-static u32 domain_sid(struct domain *dom)
+static u32 domain_sid(const struct domain *dom)
 {
     struct domain_security_struct *dsec = dom->ssid;
     return dsec->sid;
 }
 
-static u32 domain_target_sid(struct domain *src, struct domain *dst)
+static u32 domain_target_sid(const struct domain *src,
+                             const struct domain *dst)
 {
     struct domain_security_struct *ssec = src->ssid;
     struct domain_security_struct *dsec = dst->ssid;
@@ -58,7 +59,8 @@ static u32 evtchn_sid(const struct evtchn *chn)
     return chn->ssid.flask_sid;
 }
 
-static int domain_has_perm(struct domain *dom1, struct domain *dom2, 
+static int domain_has_perm(const struct domain *dom1,
+                           const struct domain *dom2,
                            u16 class, u32 perms)
 {
     u32 ssid, tsid;
@@ -1717,6 +1719,21 @@ static int flask_domain_resource_map(struct domain *d)
     return current_has_perm(d, SECCLASS_DOMAIN2, DOMAIN2__RESOURCE_MAP);
 }
 
+#ifdef CONFIG_ARGO
+static int flask_argo_register_single_source(const struct domain *d,
+                                             const struct domain *t)
+{
+    return domain_has_perm(d, t, SECCLASS_ARGO,
+                           ARGO__REGISTER_SINGLE_SOURCE);
+}
+
+static int flask_argo_register_any_source(const struct domain *d)
+{
+    return avc_has_perm(domain_sid(d), SECINITSID_XEN, SECCLASS_ARGO,
+                        ARGO__REGISTER_ANY_SOURCE, NULL);
+}
+#endif
+
 long do_flask_op(XEN_GUEST_HANDLE_PARAM(xsm_op_t) u_flask_op);
 int compat_flask_op(XEN_GUEST_HANDLE_PARAM(xsm_op_t) u_flask_op);
 
@@ -1851,6 +1868,10 @@ static struct xsm_operations flask_ops = {
 #endif
     .xen_version = flask_xen_version,
     .domain_resource_map = flask_domain_resource_map,
+#ifdef CONFIG_ARGO
+    .argo_register_single_source = flask_argo_register_single_source,
+    .argo_register_any_source = flask_argo_register_any_source,
+#endif
 };
 
 void __init flask_init(const void *policy_buffer, size_t policy_size)
diff --git a/xen/xsm/flask/policy/access_vectors b/xen/xsm/flask/policy/access_vectors
index 6fecfda..fb95c97 100644
--- a/xen/xsm/flask/policy/access_vectors
+++ b/xen/xsm/flask/policy/access_vectors
@@ -531,3 +531,14 @@ class version
 # Xen build id
     xen_build_id
 }
+
+# Class argo is used to describe the Argo interdomain communication system.
+class argo
+{
+    # Domain requesting registration of a communication ring
+    # to receive messages from a specific other domain.
+    register_single_source
+    # Domain requesting registration of a communication ring
+    # to receive messages from any other domain.
+    register_any_source
+}
diff --git a/xen/xsm/flask/policy/security_classes b/xen/xsm/flask/policy/security_classes
index cde4e1a..50ecbab 100644
--- a/xen/xsm/flask/policy/security_classes
+++ b/xen/xsm/flask/policy/security_classes
@@ -19,5 +19,6 @@ class event
 class grant
 class security
 class version
+class argo
 
 # FLASK
-- 
2.7.4


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