[libvirt] [PATCH] Blank out invalid interface names with escaped letters etc.

[Stefan Berger <stefanb@xxxxxxxxxx>]

Hunt interface names through a regular expression matcher to check whether they only contain valid characters.
Valid characters in this code are currently a-z,A-Z,0-9, and '_'.

Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxx>

---
 src/conf/domain_conf.c |   22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

Index: libvirt-acl/src/conf/domain_conf.c
===================================================================
--- libvirt-acl.orig/src/conf/domain_conf.c
+++ libvirt-acl/src/conf/domain_conf.c
@@ -28,6 +28,7 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <dirent.h>
+#include <regex.h>
 
 #include "virterror_internal.h"
 #include "datatypes.h"
@@ -1776,6 +1777,23 @@ cleanup:
 }
 
 
+static bool
+isValidIfname(const char *ifname) {
+    int rc = 1;
+    regex_t regex_ifname;
+
+    if (regcomp(&regex_ifname, "^[a-zA-Z0-9_]+$",
+                REG_NOSUB|REG_EXTENDED) != 0)
+        return 0;
+
+    if (regexec(&regex_ifname, ifname, 0, NULL, 0) != 0)
+        rc = 0;
+
+    regfree(&regex_ifname);
+    return rc;
+}
+
+
 
 /* Parse the XML definition for a network interface
  * @param node XML nodeset to parse for net definition
@@ -1859,8 +1877,10 @@ virDomainNetDefParseXML(virCapsPtr caps,
                        xmlStrEqual(cur->name, BAD_CAST "target")) {
                 ifname = virXMLPropString(cur, "dev");
                 if ((ifname != NULL) &&
-                    (STRPREFIX((const char*)ifname, "vnet"))) {
+                    ((STRPREFIX((const char*)ifname, "vnet")) ||
+                     (!isValidIfname(ifname)))) {
                     /* An auto-generated target name, blank it out */
+                    /* blank out invalid interface names */
                     VIR_FREE(ifname);
                 }
             } else if ((script == NULL) &&

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