[PATCH] virt-aa-helper should require <uuid> in XML

[Jamie Strandboge <jamie@xxxxxxxxxxxxx>]

When <uuid> is not in the XML, a virUUIDGenerate() ends up being called
which is unnecessary and can lead to crashes if /dev/urandom isn't
available because virRandomInitialize() is not called within
virt-aa-helper. This patch adds verify_xpath_context() and updates
caps_mockup() to use it.

This is https://launchpad.net/bugs/672943

-- 
Jamie Strandboge             | http://www.canonical.com

Author: Jamie Strandboge <jamie@xxxxxxxxxxxxx>
Description: virt-aa-helper should require <uuid> in XML
 When <uuid> is not in the XML, a virUUIDGenerate() ends up being called which
 is unnecessary and can lead to crashes if /dev/urandom isn't available
 because virRandomInitialize() is not called within virt-aa-helper. This patch
 adds verify_xpath_context() and updates caps_mockup() to use it.
Bug-Ubuntu: https://launchpad.net/bugs/672943

diff -Naurp libvirt.orig/src/security/virt-aa-helper.c libvirt/src/security/virt-aa-helper.c
--- libvirt.orig/src/security/virt-aa-helper.c	2010-11-11 12:32:13.000000000 -0600
+++ libvirt/src/security/virt-aa-helper.c	2010-11-11 13:28:10.000000000 -0600
@@ -605,6 +605,37 @@ catchXMLError (void *ctx, const char *ms
     }
 }
 
+static int
+verify_xpath_context(xmlXPathContextPtr ctxt)
+{
+    int rc = -1;
+    char *tmp = NULL;
+
+    if (!ctxt) {
+        vah_warning("Invalid context");
+        goto error;
+    }
+
+    /* check if have <name> */
+    if (!(tmp = virXPathString("string(./name[1])", ctxt))) {
+        vah_warning("Could not find <name>");
+        goto error;
+    }
+    VIR_FREE(tmp);
+
+    /* check if have <uuid> */
+    if (!(tmp = virXPathString("string(./uuid[1])", ctxt))) {
+        vah_warning("Could not find <uuid>");
+        goto error;
+    }
+    VIR_FREE(tmp);
+
+    rc = 0;
+
+  error:
+    return rc;
+}
+
 /*
  * Parse the xml we received to fill in the following:
  * ctl->hvm
@@ -653,6 +684,10 @@ caps_mockup(vahControl * ctl, const char
     }
     ctxt->node = root;
 
+    /* Quick sanity check for some required elements */
+    if (verify_xpath_context(ctxt) != 0)
+        goto cleanup;
+
     ctl->hvm = virXPathString("string(./os/type[1])", ctxt);
     if (!ctl->hvm || STRNEQ(ctl->hvm, "hvm")) {
         vah_error(ctl, 0, "os.type is not 'hvm'");

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