[PATCH v4 26/34] HYPERCALL_version_op: Add VERSION_OP_build_id to retrieve build-id.

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

The VERSION_OP hypercall provides the flexibility to expose
the size of the build-id (so the callers can allocate the
proper size before trying to retrieve it). It also allows
in one nice swoop to retrieve the hypervisor build-id in the
provided buffer.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
Cc: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
---
---
 tools/flask/policy/policy/modules/xen/xen.te |  4 ++--
 xen/common/kernel.c                          | 14 ++++++++++++++
 xen/include/public/version.h                 |  3 +++
 xen/xsm/flask/hooks.c                        |  3 +++
 xen/xsm/flask/policy/access_vectors          |  2 ++
 5 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/tools/flask/policy/policy/modules/xen/xen.te b/tools/flask/policy/policy/modules/xen/xen.te
index bac0c9e..e5eb666 100644
--- a/tools/flask/policy/policy/modules/xen/xen.te
+++ b/tools/flask/policy/policy/modules/xen/xen.te
@@ -82,7 +82,7 @@ allow dom0_t xen_t:version {
     xen_changeset xen_platform_parameters xen_get_features xen_pagesize
     xen_guest_handle xen_commandline
     version extraversion capabilities changeset platform_parameters
-    get_features pagesize guest_handle commandline
+    get_features pagesize guest_handle commandline build_id
 };
 
 allow dom0_t xen_t:mmu memorymap;
@@ -150,7 +150,7 @@ if (guest_writeconsole) {
 allow domain_type xen_t:xen2 pmu_use;
 
 # For normal guests all except XENVER_commandline, VERSION_OP_changeset,
-# and VERSION_OP_commandline
+# VERSION_OP_commandline, and VERSION_OP_build_info
 allow domain_type xen_t:version {
     xen_version xen_extraversion xen_compile_info xen_capabilities
     xen_changeset xen_platform_parameters xen_get_features xen_pagesize
diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index f06b3d9..96d08ed 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -390,6 +390,7 @@ DO(xen_version)(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
             return -EFAULT;
         return 0;
     }
+
     }
 
     return -ENOSYS;
@@ -455,6 +456,13 @@ static int size_of_subops_data(unsigned int cmd, ssize_t *sz)
         *sz = ARRAY_SIZE(saved_cmdline);
         break;
 
+    case XEN_VERSION_OP_build_id:
+    {
+        const void *p;
+        rc = xen_build_id(&p, sz);
+        break;
+    }
+
     default:
         rc = -ENOSYS;
     }
@@ -549,6 +557,12 @@ DO(version_op)(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) arg,
         ptr = saved_cmdline;
         break;
 
+    case XEN_VERSION_OP_build_id:
+    {
+        rc = xen_build_id(&ptr, &sz);
+        break;
+    }
+
     default:
         rc = -ENOSYS;
     }
diff --git a/xen/include/public/version.h b/xen/include/public/version.h
index 4ceb97b..ca0ffca 100644
--- a/xen/include/public/version.h
+++ b/xen/include/public/version.h
@@ -157,6 +157,9 @@ DEFINE_XEN_GUEST_HANDLE(xen_version_op_buf_t);
 /* arg = version_op_buf */
 #define XEN_VERSION_OP_commandline 9
 
+/* arg = version_op_buf */
+#define XEN_VERSION_OP_build_id 10
+
 #endif /* __XEN_PUBLIC_VERSION_H__ */
 
 /*
diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
index fb5cc4a..29debc4 100644
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -1701,6 +1701,9 @@ static int flask_version_op (uint32_t op)
     case XEN_VERSION_OP_commandline:
         return avc_has_perm(dsid, SECINITSID_XEN, SECCLASS_VERSION,
                             VERSION__COMMANDLINE, NULL);
+    case XEN_VERSION_OP_build_id:
+        return avc_has_perm(dsid, SECINITSID_XEN, SECCLASS_VERSION,
+                            VERSION__BUILD_ID, NULL);
     default:
         return -EPERM;
     }
diff --git a/xen/xsm/flask/policy/access_vectors b/xen/xsm/flask/policy/access_vectors
index a227f88..5ff47c2 100644
--- a/xen/xsm/flask/policy/access_vectors
+++ b/xen/xsm/flask/policy/access_vectors
@@ -544,4 +544,6 @@ class version
     guest_handle
 # Xen command line.
     commandline
+# Build id of the hypervisor
+    build_id
 }
-- 
2.5.0


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