[PATCH v7 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.

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>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Tested-by: Chris Patterson <pattersonc@ainfosec.com>
---
v6 Chris: apply const to avc_audit_data sdom and tdom struct members
v6 Chris: apply const to args in dummy.h function signatures
v6 Chris: fix missing return type in xsm.h inline functions
v3 Daniel/Jan: add to the default xsm policy for the register op
v3 hoist opt_argo_mac_permissive check to allow default policy to match non-XSM
v3 was: Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
v3 Add Daniel's Acked-by ; note minor changes required for v4
v3 feedback #07 Roger: use opt_argo_mac_permissive : a boolean opt
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

 tools/flask/policy/modules/guest_features.te |  6 ++++++
 xen/common/argo.c                            | 11 +++++++++--
 xen/include/xsm/dummy.h                      | 14 ++++++++++++++
 xen/include/xsm/xsm.h                        | 19 +++++++++++++++++++
 xen/xsm/dummy.c                              |  4 ++++
 xen/xsm/flask/hooks.c                        | 27 ++++++++++++++++++++++++---
 xen/xsm/flask/include/avc.h                  |  4 ++--
 xen/xsm/flask/policy/access_vectors          | 11 +++++++++++
 xen/xsm/flask/policy/security_classes        |  1 +
 9 files changed, 90 insertions(+), 7 deletions(-)

diff --git a/tools/flask/policy/modules/guest_features.te b/tools/flask/policy/modules/guest_features.te
index 9ac9780..d00769e 100644
--- a/tools/flask/policy/modules/guest_features.te
+++ b/tools/flask/policy/modules/guest_features.te
@@ -5,6 +5,12 @@ allow domain_type xen_t:xen tmem_op;
 # pmu_ctrl is for)
 allow domain_type xen_t:xen2 pmu_use;
 
+# Allow all domains:
+# to register single-sender (unicast) rings to partner with any domain; and
+# to register any-sender (wildcard) rings that can be sent to by any domain.
+allow domain_type xen_t:argo { register_any_source };
+allow domain_type domain_type:argo { register_single_source };
+
 # Allow guest console output to the serial console.  This is used by PV Linux
 # and stub domains for early boot output, so don't audit even when we deny it.
 # Without XSM, this is enabled only if the Xen was compiled in debug mode.
diff --git a/xen/common/argo.c b/xen/common/argo.c
index 78d6f00..5c1e711 100644
--- a/xen/common/argo.c
+++ b/xen/common/argo.c
@@ -26,6 +26,7 @@
 #include <xen/nospec.h>
 #include <xen/sched.h>
 #include <xen/time.h>
+#include <xsm/xsm.h>
 
 #include <public/argo.h>
 
@@ -1676,8 +1677,10 @@ register_ring(struct domain *currd,
 
     if ( reg.partner_id == XEN_ARGO_DOMID_ANY )
     {
-        if ( !opt_argo_mac_permissive )
-            return -EPERM;
+        ret = opt_argo_mac_permissive ? xsm_argo_register_any_source(currd) :
+                                        -EPERM;
+        if ( ret )
+            return ret;
     }
     else
     {
@@ -1688,6 +1691,10 @@ register_ring(struct domain *currd,
             return -ESRCH;
         }
 
+        ret = xsm_argo_register_single_source(currd, dst_d);
+        if ( ret )
+            goto out;
+
         send_info = xzalloc(struct argo_send_info);
         if ( !send_info )
         {
diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h
index a29d1ef..9abfd69 100644
--- a/xen/include/xsm/dummy.h
+++ b/xen/include/xsm/dummy.h
@@ -720,6 +720,20 @@ 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(const struct domain *d,
+                                                      const struct domain *t)
+{
+    return 0;
+}
+
+static XSM_INLINE int xsm_argo_register_any_source(const struct domain *d)
+{
+    return 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..0b40714 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 int xsm_argo_register_single_source(const struct domain *d,
+                                                  const struct domain *t)
+{
+    return xsm_ops->argo_register_single_source(d, t);
+}
+
+static inline int xsm_argo_register_any_source(const struct domain *d)
+{
+    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/include/avc.h b/xen/xsm/flask/include/avc.h
index 4046516..93386bd 100644
--- a/xen/xsm/flask/include/avc.h
+++ b/xen/xsm/flask/include/avc.h
@@ -40,8 +40,8 @@ struct avc_audit_data {
 #define AVC_AUDIT_DATA_RANGE 3
 #define AVC_AUDIT_DATA_MEMORY 4
 #define AVC_AUDIT_DATA_DTDEV 5
-    struct domain *sdom;
-    struct domain *tdom;
+    const struct domain *sdom;
+    const struct domain *tdom;
     union {
         unsigned long device;
         int irq;
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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