[Xen-devel] [PATCH v1 1/4] xsm/libxl/xen_version: Add XSM for some of the xen_version commands.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

The XENVER_[compile_info|changeset|commandline] are now
guarded by an XSM check.

The rest: XENVER_[version|extraversion|capabilities|
parameters|get_features|page_size|guest_handle] behave
as before (no XSM check).

We allow the initial domain to see these while the other
guests are not permitted.

As such we also modify the toolstack such that if we fail
to get any data instead of printing (null) we just print "".

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 tools/flask/policy/policy/modules/xen/xen.te |  2 +-
 tools/libxl/libxl.c                          |  3 +++
 xen/common/kernel.c                          | 11 ++++++++++-
 xen/include/xsm/dummy.h                      | 24 ++++++++++++++++++++++++
 xen/include/xsm/xsm.h                        |  6 ++++++
 xen/xsm/dummy.c                              |  1 +
 xen/xsm/flask/hooks.c                        | 25 +++++++++++++++++++++++++
 xen/xsm/flask/policy/access_vectors          |  2 ++
 8 files changed, 72 insertions(+), 2 deletions(-)

diff --git a/tools/flask/policy/policy/modules/xen/xen.te 
b/tools/flask/policy/policy/modules/xen/xen.te
index d35ae22..d0ad758 100644
--- a/tools/flask/policy/policy/modules/xen/xen.te
+++ b/tools/flask/policy/policy/modules/xen/xen.te
@@ -86,7 +86,7 @@ allow dom0_t dom0_t:domain {
 };
 allow dom0_t dom0_t:domain2 {
        set_cpuid gettsc settsc setscheduler set_max_evtchn set_vnumainfo
-       get_vnumainfo psr_cmt_op psr_cat_op
+       get_vnumainfo psr_cmt_op psr_cat_op version_use
 };
 allow dom0_t dom0_t:resource { add remove };
 
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 22bbc29..efa6462 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -5272,6 +5272,7 @@ const libxl_version_info* 
libxl_get_version_info(libxl_ctx *ctx)
     xc_version(ctx->xch, XENVER_extraversion, &u.xen_extra);
     info->xen_version_extra = strdup(u.xen_extra);
 
+    memset(&u.xen_cc, 0, sizeof(xen_compile_info_t));
     xc_version(ctx->xch, XENVER_compile_info, &u.xen_cc);
     info->compiler = strdup(u.xen_cc.compiler);
     info->compile_by = strdup(u.xen_cc.compile_by);
@@ -5281,6 +5282,7 @@ const libxl_version_info* 
libxl_get_version_info(libxl_ctx *ctx)
     xc_version(ctx->xch, XENVER_capabilities, &u.xen_caps);
     info->capabilities = strdup(u.xen_caps);
 
+    memset(&u.xen_cc, 0, sizeof(xen_changeset_info_t));
     xc_version(ctx->xch, XENVER_changeset, &u.xen_chgset);
     info->changeset = strdup(u.xen_chgset);
 
@@ -5289,6 +5291,7 @@ const libxl_version_info* 
libxl_get_version_info(libxl_ctx *ctx)
 
     info->pagesize = xc_version(ctx->xch, XENVER_pagesize, NULL);
 
+    memset(&u.xen_commandline, 0, sizeof(xen_commandline_t));
     xc_version(ctx->xch, XENVER_commandline, &u.xen_commandline);
     info->commandline = strdup(u.xen_commandline);
 
diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index 6a3196a..210ec99 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -13,6 +13,7 @@
 #include <xen/nmi.h>
 #include <xen/guest_access.h>
 #include <xen/hypercall.h>
+#include <xsm/xsm.h>
 #include <asm/current.h>
 #include <public/nmi.h>
 #include <public/version.h>
@@ -226,9 +227,17 @@ void __init do_initcalls(void)
 /*
  * Simple hypercalls.
  */
-
+#define XENVER_CMD_XSM_CHECK    ( (1U << XENVER_compile_info) | \
+                                  (1U << XENVER_changeset) | \
+                                  (1U << XENVER_commandline) )
 DO(xen_version)(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 {
+    if ( ( 1 << cmd ) & XENVER_CMD_XSM_CHECK )
+    {
+        int rc = xsm_version_op(XSM_PRIV, cmd);
+        if ( rc )
+            return rc;
+    }
     switch ( cmd )
     {
     case XENVER_version:
diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h
index 9fe372c..2ee102e 100644
--- a/xen/include/xsm/dummy.h
+++ b/xen/include/xsm/dummy.h
@@ -720,4 +720,28 @@ static XSM_INLINE int xsm_pmu_op (XSM_DEFAULT_ARG struct 
domain *d, unsigned int
     }
 }
 
+#include <public/version.h>
+static XSM_INLINE int xsm_version_op (XSM_DEFAULT_ARG uint32_t op)
+{
+    XSM_ASSERT_ACTION(XSM_PRIV);
+    switch ( op )
+    {
+    case XENVER_compile_info:
+    case XENVER_changeset:
+    case XENVER_commandline:
+        return xsm_default_action(XSM_PRIV, current->domain, NULL);
+    case XENVER_version:
+    case XENVER_extraversion:
+    case XENVER_capabilities:
+    case XENVER_platform_parameters:
+    case XENVER_get_features:
+    case XENVER_pagesize:
+    case XENVER_guest_handle:
+        /* The should _NEVER_ get here, but just in case. */
+        return xsm_default_action(XSM_HOOK, current->domain, NULL);
+    default:
+        return -EPERM;
+    }
+}
+
 #endif /* CONFIG_X86 */
diff --git a/xen/include/xsm/xsm.h b/xen/include/xsm/xsm.h
index ba3caed..cd3e9b8 100644
--- a/xen/include/xsm/xsm.h
+++ b/xen/include/xsm/xsm.h
@@ -191,6 +191,7 @@ struct xsm_operations {
     int (*ioport_mapping) (struct domain *d, uint32_t s, uint32_t e, uint8_t 
allow);
     int (*pmu_op) (struct domain *d, unsigned int op);
 #endif
+    int (*version_op) (uint32_t cmd);
 };
 
 #ifdef XSM_ENABLE
@@ -727,6 +728,11 @@ static inline int xsm_pmu_op (xsm_default_t def, struct 
domain *d, unsigned int
     return xsm_ops->pmu_op(d, op);
 }
 
+static inline int xsm_version_op (xsm_default_t def, uint32_t op)
+{
+    return xsm_ops->version_op(op);
+}
+
 #endif /* CONFIG_X86 */
 
 #endif /* XSM_NO_WRAPPERS */
diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c
index 72eba40..6105c07 100644
--- a/xen/xsm/dummy.c
+++ b/xen/xsm/dummy.c
@@ -162,4 +162,5 @@ void xsm_fixup_ops (struct xsm_operations *ops)
     set_to_dummy_if_null(ops, ioport_mapping);
     set_to_dummy_if_null(ops, pmu_op);
 #endif
+    set_to_dummy_if_null(ops, version_op);
 }
diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
index 4180f3b..4f1269d 100644
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -26,6 +26,7 @@
 #include <public/xen.h>
 #include <public/physdev.h>
 #include <public/platform.h>
+#include <public/version.h>
 
 #include <public/xsm/flask_op.h>
 
@@ -1621,6 +1622,29 @@ static int flask_pmu_op (struct domain *d, unsigned int 
op)
 }
 #endif /* CONFIG_X86 */
 
+static int flask_version_op (uint32_t op)
+{
+    switch ( op )
+    {
+    case XENVER_compile_info:
+    case XENVER_changeset:
+    case XENVER_commandline:
+        return current_has_perm(current->domain, SECCLASS_DOMAIN2,
+                                DOMAIN2__VERSION_USE);
+    case XENVER_version:
+    case XENVER_extraversion:
+    case XENVER_capabilities:
+    case XENVER_platform_parameters:
+    case XENVER_get_features:
+    case XENVER_pagesize:
+    case XENVER_guest_handle:
+        /* The XSM check is only for a subset of ops. The rest are allowed. */
+        return 0;
+    default:
+        return -EPERM;
+    }
+}
+
 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);
 
@@ -1759,6 +1783,7 @@ static struct xsm_operations flask_ops = {
     .ioport_mapping = flask_ioport_mapping,
     .pmu_op = flask_pmu_op,
 #endif
+    .version_op = flask_version_op,
 };
 
 static __init void flask_init(void)
diff --git a/xen/xsm/flask/policy/access_vectors 
b/xen/xsm/flask/policy/access_vectors
index effb59f..6e2e5d1 100644
--- a/xen/xsm/flask/policy/access_vectors
+++ b/xen/xsm/flask/policy/access_vectors
@@ -242,6 +242,8 @@ class domain2
     mem_sharing
 # XEN_DOMCTL_psr_cat_op
     psr_cat_op
+# XENVER_[compile_info|changeset|commandline] usage. The rest is not checked.
+   version_use
 }
 
 # Similar to class domain, but primarily contains domctls related to HVM 
domains
-- 
2.1.0


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