libvirt/922b7fda-CVE-2013-4311.patch

commit 922b7fda77b094dbf022d625238262ea05335666
Author: Daniel P. Berrange <berrange@redhat.com>
Date:   Wed Aug 28 15:25:40 2013 +0100

    Add support for using 3-arg pkcheck syntax for process (CVE-2013-4311)
    
    With the existing pkcheck (pid, start time) tuple for identifying
    the process, there is a race condition, where a process can make
    a libvirt RPC call and in another thread exec a setuid application,
    causing it to change to effective UID 0. This in turn causes polkit
    to do its permission check based on the wrong UID.
    
    To address this, libvirt must get the UID the caller had at time
    of connect() (from SO_PEERCRED) and pass a (pid, start time, uid)
    triple to the pkcheck program.
    
    This fix requires that libvirt is re-built against a version of
    polkit that has the fix for its CVE-2013-4288, so that libvirt
    can see 'pkg-config --variable pkcheck_supports_uid polkit-gobject-1'
    
    Signed-off-by: Colin Walters <walters@redhat.com>
    Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

Index: libvirt-1.1.2/configure.ac
===================================================================
--- libvirt-1.1.2.orig/configure.ac
+++ libvirt-1.1.2/configure.ac
@@ -1184,6 +1184,14 @@ if test "x$with_polkit" = "xyes" || test
   AC_PATH_PROG([PKCHECK_PATH],[pkcheck], [], [/usr/sbin:$PATH])
   if test "x$PKCHECK_PATH" != "x" ; then
     AC_DEFINE_UNQUOTED([PKCHECK_PATH],["$PKCHECK_PATH"],[Location of pkcheck program])
+    AC_MSG_CHECKING([whether pkcheck supports uid value])
+    pkcheck_supports_uid=`$PKG_CONFIG --variable pkcheck_supports_uid polkit-gobject-1`
+    if test "x$pkcheck_supports_uid" = "xtrue"; then
+      AC_MSG_RESULT([yes])
+      AC_DEFINE_UNQUOTED([PKCHECK_SUPPORTS_UID], 1, [Pass uid to pkcheck])
+    else
+      AC_MSG_RESULT([no])
+    fi
     AC_DEFINE_UNQUOTED([WITH_POLKIT], 1,
         [use PolicyKit for UNIX socket access checks])
     AC_DEFINE_UNQUOTED([WITH_POLKIT1], 1,
Index: libvirt-1.1.2/daemon/remote.c
===================================================================
--- libvirt-1.1.2.orig/daemon/remote.c
+++ libvirt-1.1.2/daemon/remote.c
@@ -2738,10 +2738,12 @@ remoteDispatchAuthPolkit(virNetServerPtr
     int status = -1;
     char *ident = NULL;
     bool authdismissed = 0;
+    bool supportsuid = false;
     char *pkout = NULL;
     struct daemonClientPrivate *priv =
         virNetServerClientGetPrivateData(client);
     virCommandPtr cmd = NULL;
+    static bool polkitInsecureWarned;
 
     virMutexLock(&priv->lock);
     action = virNetServerClientGetReadonly(client) ?
@@ -2763,14 +2765,28 @@ remoteDispatchAuthPolkit(virNetServerPtr
         goto authfail;
     }
 
+    if (timestamp == 0) {
+        VIR_WARN("Failing polkit auth due to missing client (pid=%lld) start time",
+                 (long long)callerPid);
+        goto authfail;
+    }
+
     VIR_INFO("Checking PID %lld running as %d",
              (long long) callerPid, callerUid);
 
     virCommandAddArg(cmd, "--process");
-    if (timestamp != 0) {
-        virCommandAddArgFormat(cmd, "%lld,%llu", (long long) callerPid, timestamp);
+# ifdef PKCHECK_SUPPORTS_UID
+    supportsuid = true;
+# endif
+    if (supportsuid) {
+        virCommandAddArgFormat(cmd, "%lld,%llu,%lu",
+                               (long long) callerPid, timestamp, (unsigned long) callerUid);
     } else {
-        virCommandAddArgFormat(cmd, "%lld", (long long) callerPid);
+        if (!polkitInsecureWarned) {
+            VIR_WARN("No support for caller UID with pkcheck. This deployment is known to be insecure.");
+            polkitInsecureWarned = true;
+        }
+        virCommandAddArgFormat(cmd, "%lld,%llu", (long long) callerPid, timestamp);
     }
     virCommandAddArg(cmd, "--allow-user-interaction");
 
Index: libvirt-1.1.2/libvirt.spec.in
===================================================================
--- libvirt-1.1.2.orig/libvirt.spec.in
+++ libvirt-1.1.2/libvirt.spec.in
@@ -508,8 +508,7 @@ BuildRequires: cyrus-sasl-devel
 %endif
 %if %{with_polkit}
     %if 0%{?fedora} >= 12 || 0%{?rhel} >= 6
-# Only need the binary, not -devel
-BuildRequires: polkit >= 0.93
+BuildRequires: polkit-devel >= 0.93
     %else
 BuildRequires: PolicyKit-devel >= 0.6
     %endif
Index: libvirt-1.1.2/src/access/viraccessdriverpolkit.c
===================================================================
--- libvirt-1.1.2.orig/src/access/viraccessdriverpolkit.c
+++ libvirt-1.1.2/src/access/viraccessdriverpolkit.c
@@ -72,8 +72,12 @@ static char *
 virAccessDriverPolkitFormatProcess(const char *actionid)
 {
     virIdentityPtr identity = virIdentityGetCurrent();
-    const char *process = NULL;
+    const char *callerPid = NULL;
+    const char *callerTime = NULL;
+    const char *callerUid = NULL;
     char *ret = NULL;
+    bool supportsuid = false;
+    static bool polkitInsecureWarned;
 
     if (!identity) {
         virAccessError(VIR_ERR_ACCESS_DENIED,
@@ -81,17 +85,43 @@ virAccessDriverPolkitFormatProcess(const
                        actionid);
         return NULL;
     }
-    if (virIdentityGetAttr(identity, VIR_IDENTITY_ATTR_UNIX_PROCESS_ID, &process) < 0)
+    if (virIdentityGetAttr(identity, VIR_IDENTITY_ATTR_UNIX_PROCESS_ID, &callerPid) < 0)
+        goto cleanup;
+    if (virIdentityGetAttr(identity, VIR_IDENTITY_ATTR_UNIX_PROCESS_TIME, &callerTime) < 0)
+        goto cleanup;
+    if (virIdentityGetAttr(identity, VIR_IDENTITY_ATTR_UNIX_USER_ID, &callerUid) < 0)
         goto cleanup;
 
-    if (!process) {
+    if (!callerPid) {
         virAccessError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("No UNIX process ID available"));
         goto cleanup;
     }
-
-    if (VIR_STRDUP(ret, process) < 0)
+    if (!callerTime) {
+        virAccessError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("No UNIX process start time available"));
+        goto cleanup;
+    }
+    if (!callerUid) {
+        virAccessError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("No UNIX caller UID available"));
         goto cleanup;
+    }
+
+#ifdef PKCHECK_SUPPORTS_UID
+    supportsuid = true;
+#endif
+    if (supportsuid) {
+        if (virAsprintf(&ret, "%s,%s,%s", callerPid, callerTime, callerUid) < 0)
+            goto cleanup;
+    } else {
+        if (!polkitInsecureWarned) {
+            VIR_WARN("No support for caller UID with pkcheck. This deployment is known to be insecure.");
+            polkitInsecureWarned = true;
+        }
+        if (virAsprintf(&ret, "%s,%s", callerPid, callerTime) < 0)
+            goto cleanup;
+    }
 
 cleanup:
     virObjectUnref(identity);