[libvirt] [PATCH] fix parsing security labels from virt-aa-helper

[Christian Ehrhardt]

When parsing labels virt-aa-helper does no more pass
VIR_DOMAIN_DEF_PARSE_INACTIVE due to dfbc9a83 that tried to mitigate the
changes of a89f05ba. For those it had to switch from
VIR_DOMAIN_DEF_PARSE_INACTIVE to active since we need the domain id
(ctl->def->id) as it is part of the socket path now which is needed for the
aa profile.

But that turned out to break non apparmor seclabels as well as apparmor
seclabels in xmls without labels.
In those cases due to VIR_DOMAIN_DEF_PARSE_INACTIVE now not set anymore
virSecurityLabelDefParseXML insists on finding labels. Cases:
- non-apparmor seclabel - virt-aa-helper breaks
- apparmor seclabel without labels on a defined domain - virt-aa-helper breaks
This was not spotted due to labels getting dynamically created on definition.
So "define, start, stop" works. But "define, edit (add label), start" does not.

Now turning back on VIR_DOMAIN_DEF_PARSE_INACTIVE would cause the old bug, so
we have to differ those more fine grained. This is done by the new flag
VIR_DOMAIN_DEF_PARSE_SKIP_ACTIVE_LABEL which is like
VIR_DOMAIN_DEF_PARSE_INACTIVE but only for the security labels.
So far only set by virt-aa-helper.

Testcase with virt-aa-helper on xml file:
 virt-aa-helper -d -r -p 0 -u libvirt-<uuid> < your-guest.xml
   virt-aa-helper: error: could not parse XML
   virt-aa-helper: error: could not get VM definition
(That should have printed a valid apparmor profile)

Signed-off-by: Christian Ehrhardt <christian.ehrhardt at canonical.com>
---
 src/conf/domain_conf.c        | 6 ++++--
 src/conf/domain_conf.h        | 3 +++
 src/security/virt-aa-helper.c | 1 +
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 03506cb..9eb7883 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -6626,7 +6626,8 @@ virSecurityLabelDefParseXML(xmlXPathContextPtr ctxt,
      * if the 'live' VM XML is requested
      */
     if (seclabel->type == VIR_DOMAIN_SECLABEL_STATIC ||
-        (!(flags & VIR_DOMAIN_DEF_PARSE_INACTIVE) &&
+        (!(flags & (VIR_DOMAIN_DEF_PARSE_SKIP_ACTIVE_LABEL |
+                    VIR_DOMAIN_DEF_PARSE_INACTIVE)) &&
          seclabel->type != VIR_DOMAIN_SECLABEL_NONE)) {
         p = virXPathStringLimit("string(./label[1])",
                                 VIR_SECURITY_LABEL_BUFLEN-1, ctxt);
@@ -6642,7 +6643,8 @@ virSecurityLabelDefParseXML(xmlXPathContextPtr ctxt,
 
     /* Only parse imagelabel, if requested live XML with relabeling */
     if (seclabel->relabel &&
-        (!(flags & VIR_DOMAIN_DEF_PARSE_INACTIVE) &&
+        (!(flags & (VIR_DOMAIN_DEF_PARSE_SKIP_ACTIVE_LABEL |
+                    VIR_DOMAIN_DEF_PARSE_INACTIVE)) &&
          seclabel->type != VIR_DOMAIN_SECLABEL_NONE)) {
         p = virXPathStringLimit("string(./imagelabel[1])",
                                 VIR_SECURITY_LABEL_BUFLEN-1, ctxt);
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 24aa79c..90693c6 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -2657,6 +2657,9 @@ typedef enum {
     VIR_DOMAIN_DEF_PARSE_ABI_UPDATE = 1 << 9,
     /* skip definition validation checks meant to be executed on define time only */
     VIR_DOMAIN_DEF_PARSE_SKIP_VALIDATE = 1 << 10,
+    /* in regard to security labels, skip parts of the XML that would only be
+     * present in an active libvirt XML. */
+    VIR_DOMAIN_DEF_PARSE_SKIP_ACTIVE_LABEL        = 1 << 11,
 } virDomainDefParseFlags;
 
 typedef enum {
diff --git a/src/security/virt-aa-helper.c b/src/security/virt-aa-helper.c
index 77eeaff..0ca4c83 100644
--- a/src/security/virt-aa-helper.c
+++ b/src/security/virt-aa-helper.c
@@ -705,6 +705,7 @@ get_definition(vahControl * ctl, const char *xmlStr)
 
     ctl->def = virDomainDefParseString(xmlStr,
                                        ctl->caps, ctl->xmlopt, NULL,
+                                       VIR_DOMAIN_DEF_PARSE_SKIP_ACTIVE_LABEL |
                                        VIR_DOMAIN_DEF_PARSE_SKIP_VALIDATE);
 
     if (ctl->def == NULL) {
-- 
2.7.4