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[libvirt] PATCH: Mark <seclabel> as dynamic generated, or statically pre-defined



This patch implements the behaviour I was refering to earlier, whereby
the domain XML explicitly says whether the security label is a statically
pre-defined one, or dynamically generated on VM boot by libvirtd

So when creating a new guest, apps like virt-install have 2 options:

 - Leave out the <seclabel> tag completely
    -> If no security driver is active, just works as normal unconfined VM
    -> If a security driver is active, a dynamic seclabel is generated

      <seclabel type='dynamic' model='selinux'>
        <label>system_u:system_r:qemu_t:s0:c424,c719</label>
        <imagelabel>system_u:object_r:virt_image_t:s0:c424,c719</imagelabel>
      </seclabel>

 - Add an explicit <seclabel> tag with type='static' attribute
    -> Security driver uses the defined label & imagelabel

      <seclabel type='static' model='selinux'>
        <label>system_u:system_r:qemu_t:s0:c25,c100</label>
        <imagelabel>system_u:system_r:virt_image_t:s0:c25,c100</imagelabel>
      </seclabel>


A static seclabel is visible in the XML, at all times, whether the VM is
active or inactive. 

A dynamic seclabel is only visible when the VM is running, since it is
auto-generated at VM boot. If you migrate the VM, or save/restore it,
the dynamic seclabel will change on each boot. The seclabel isn't visible
when not running, or if asking for the inactive XML dump

This patch implements parsing of the 'type' attribute, and makes the
seclabel generation key off this attribute.

It also adds the 'imagelabel' XML element, since that was being used
internally, but was not including in the XML output, or parsing
routines, making it impossible to specify a pre-defined image label
or see the dyanmic one

 domain_conf.c      |   65 +++++++++++++++++++++++++++++++++++++++++++----------
 domain_conf.h      |    9 +++++++
 qemu_driver.c      |   13 ++++++++--
 security_selinux.c |    1 
 4 files changed, 73 insertions(+), 15 deletions(-)


Daniel

Index: src/domain_conf.c
===================================================================
RCS file: /data/cvs/libvirt/src/domain_conf.c,v
retrieving revision 1.70
diff -u -p -r1.70 domain_conf.c
--- src/domain_conf.c	3 Mar 2009 09:44:42 -0000	1.70
+++ src/domain_conf.c	3 Mar 2009 15:36:02 -0000
@@ -168,6 +168,10 @@ VIR_ENUM_IMPL(virDomainState, VIR_DOMAIN
               "shutoff",
               "crashed")
 
+VIR_ENUM_IMPL(virDomainSeclabel, VIR_DOMAIN_SECLABEL_LAST,
+              "dynamic",
+              "static")
+
 #define virDomainReportError(conn, code, fmt...)                           \
         virReportErrorHelper(conn, VIR_FROM_DOMAIN, code, __FILE__,        \
                                __FUNCTION__, __LINE__, fmt)
@@ -1847,24 +1851,46 @@ static int virDomainLifecycleParseXML(vi
 static int
 virSecurityLabelDefParseXML(virConnectPtr conn,
                             const virDomainDefPtr def,
-                            xmlXPathContextPtr ctxt)
+                            xmlXPathContextPtr ctxt,
+                            int flags)
 {
     char *p;
 
     if (virXPathNode(conn, "./seclabel", ctxt) == NULL)
         return 0;
 
-    p = virXPathStringLimit(conn, "string(./seclabel/label[1])",
+    p = virXPathStringLimit(conn, "string(./seclabel/@type)",
                             VIR_SECURITY_LABEL_BUFLEN-1, ctxt);
     if (p == NULL)
         goto error;
-    def->seclabel.label = p;
-
-    p = virXPathStringLimit(conn, "string(./seclabel/@model)",
-                            VIR_SECURITY_MODEL_BUFLEN-1, ctxt);
-    if (p == NULL)
+    if ((def->seclabel.type = virDomainSeclabelTypeFromString(p)) < 0)
         goto error;
-    def->seclabel.model = p;
+    VIR_FREE(p);
+
+    /* Only parse details, if using static labels, or
+     * if the 'live' VM XML is requested
+     */
+    if (def->seclabel.type == VIR_DOMAIN_SECLABEL_STATIC ||
+        !(flags & VIR_DOMAIN_XML_INACTIVE)) {
+        p = virXPathStringLimit(conn, "string(./seclabel/@model)",
+                                VIR_SECURITY_MODEL_BUFLEN-1, ctxt);
+        if (p == NULL)
+            goto error;
+        def->seclabel.model = p;
+
+        p = virXPathStringLimit(conn, "string(./seclabel/label[1])",
+                                VIR_SECURITY_LABEL_BUFLEN-1, ctxt);
+        if (p == NULL)
+            goto error;
+        def->seclabel.label = p;
+
+        p = virXPathStringLimit(conn, "string(./seclabel/imagelabel[1])",
+                                VIR_SECURITY_LABEL_BUFLEN-1, ctxt);
+        if (p == NULL)
+            goto error;
+        def->seclabel.imagelabel = p;
+
+    }
 
     return 0;
 
@@ -2458,7 +2484,7 @@ static virDomainDefPtr virDomainDefParse
     VIR_FREE(nodes);
 
     /* analysis of security label */
-    if (virSecurityLabelDefParseXML(conn, def, ctxt) == -1)
+    if (virSecurityLabelDefParseXML(conn, def, ctxt, flags) == -1)
         goto error;
 
     return def;
@@ -3480,9 +3506,24 @@ char *virDomainDefFormat(virConnectPtr c
     virBufferAddLit(&buf, "  </devices>\n");
 
     if (def->seclabel.model) {
-        virBufferEscapeString(&buf, "  <seclabel model='%s'>\n", def->seclabel.model);
-        virBufferEscapeString(&buf, "    <label>%s</label>\n", def->seclabel.label);
-        virBufferAddLit(&buf, "  </seclabel>\n");
+        const char *sectype = virDomainSeclabelTypeToString(def->seclabel.type);
+        if (!sectype)
+            goto cleanup;
+        if (!def->seclabel.label ||
+            (def->seclabel.type == VIR_DOMAIN_SECLABEL_DYNAMIC &&
+             (flags & VIR_DOMAIN_XML_INACTIVE))) {
+            virBufferVSprintf(&buf, "  <seclabel type='%s' model='%s'/>\n",
+                              sectype, def->seclabel.model);
+        } else {
+            virBufferVSprintf(&buf, "  <seclabel type='%s' model='%s'>\n",
+                                  sectype, def->seclabel.model);
+            virBufferEscapeString(&buf, "    <label>%s</label>\n",
+                                  def->seclabel.label);
+            if (def->seclabel.imagelabel)
+                virBufferEscapeString(&buf, "    <imagelabel>%s</imagelabel>\n",
+                                      def->seclabel.imagelabel);
+            virBufferAddLit(&buf, "  </seclabel>\n");
+        }
     }
 
     virBufferAddLit(&buf, "</domain>\n");
Index: src/domain_conf.h
===================================================================
RCS file: /data/cvs/libvirt/src/domain_conf.h,v
retrieving revision 1.39
diff -u -p -r1.39 domain_conf.h
--- src/domain_conf.h	3 Mar 2009 09:44:42 -0000	1.39
+++ src/domain_conf.h	3 Mar 2009 15:36:02 -0000
@@ -410,6 +410,13 @@ struct _virDomainOSDef {
     char *bootloaderArgs;
 };
 
+enum virDomainSeclabelType {
+    VIR_DOMAIN_SECLABEL_DYNAMIC,
+    VIR_DOMAIN_SECLABEL_STATIC,
+
+    VIR_DOMAIN_SECLABEL_LAST,
+};
+
 /* Security configuration for domain */
 typedef struct _virSecurityLabelDef virSecurityLabelDef;
 typedef virSecurityLabelDef *virSecurityLabelDefPtr;
@@ -417,6 +424,7 @@ struct _virSecurityLabelDef {
     char *model;        /* name of security model */
     char *label;        /* security label string */
     char *imagelabel;   /* security image label string */
+    int type;
 };
 
 #define VIR_DOMAIN_CPUMASK_LEN 1024
@@ -650,5 +658,6 @@ VIR_ENUM_DECL(virDomainInputBus)
 VIR_ENUM_DECL(virDomainGraphics)
 /* from libvirt.h */
 VIR_ENUM_DECL(virDomainState)
+VIR_ENUM_DECL(virDomainSeclabel)
 
 #endif /* __DOMAIN_CONF_H */
Index: src/qemu_driver.c
===================================================================
RCS file: /data/cvs/libvirt/src/qemu_driver.c,v
retrieving revision 1.213
diff -u -p -r1.213 qemu_driver.c
--- src/qemu_driver.c	3 Mar 2009 15:18:24 -0000	1.213
+++ src/qemu_driver.c	3 Mar 2009 15:36:02 -0000
@@ -1314,9 +1314,9 @@ static int qemudStartVMDaemon(virConnect
     hookData.vm = vm;
     hookData.driver = driver;
 
-   /* If you are using a SecurityDriver and there was no security label in
-      database, then generate a security label for isolation */
-    if (vm->def->seclabel.label == NULL &&
+   /* If you are using a SecurityDriver with dynamic labelling, 
+      then generate a security label for isolation */
+    if (vm->def->seclabel.type == VIR_DOMAIN_SECLABEL_DYNAMIC &&
         driver->securityDriver &&
         driver->securityDriver->domainGenSecurityLabel &&
         driver->securityDriver->domainGenSecurityLabel(conn, vm) < 0)
@@ -1525,6 +1525,13 @@ static void qemudShutdownVMDaemon(virCon
     if (driver->securityDriver)
         driver->securityDriver->domainRestoreSecurityLabel(conn, vm);
 
+    /* Clear out dynamically assigned labels */
+    if (vm->def->seclabel.type == VIR_DOMAIN_SECLABEL_DYNAMIC) {
+        VIR_FREE(vm->def->seclabel.model);
+        VIR_FREE(vm->def->seclabel.label);
+        VIR_FREE(vm->def->seclabel.imagelabel);
+    }
+
     if (qemudRemoveDomainStatus(conn, driver, vm) < 0) {
         VIR_WARN(_("Failed to remove domain status for %s"),
                  vm->def->name);
Index: src/security_selinux.c
===================================================================
RCS file: /data/cvs/libvirt/src/security_selinux.c,v
retrieving revision 1.2
diff -u -p -r1.2 security_selinux.c
--- src/security_selinux.c	3 Mar 2009 15:18:24 -0000	1.2
+++ src/security_selinux.c	3 Mar 2009 15:36:02 -0000
@@ -161,6 +161,7 @@ SELinuxGenSecurityLabel(virConnectPtr co
     char *scontext = NULL;
     int c1 = 0;
     int c2 = 0;
+
     if ( ( vm->def->seclabel.label ) ||
          ( vm->def->seclabel.model ) ||
          ( vm->def->seclabel.imagelabel )) {


-- 
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