Don't accept unix: connections, etc. in OpenFlow controller discovery.

The controller discovery code has always had the capability to whitelist
only certain types of controller locations.  Until now, we have only taken
advantage of this when SSL is enabled (so that all OpenFlow connections are
authenticated with SSL if SSL is configured).

However, it occurs to me that making the section of connections entirely
unrestricted is too permissive.  An attacker could make the vswitch connect
to an arbitrary Unix domain socket, for example.  I don't have a
description of how this is an exploitable security vulnerability, but it
seems entirely too lax.

So: this commit changes the default to allowing only TCP connections to
controller in the non-SSL case.

diff --git a/secchan/discovery.c b/secchan/discovery.c
index 06de6f0..92d0d92 100644 (file)
--- a/secchan/discovery.c
+++ b/secchan/discovery.c
@@ -168,7 +168,7 @@ discovery_set_accept_controller_re(struct discovery *d, const char *re_)
     int error;
     char *re;
 
-    re = (!re_ ? xstrdup(vconn_ssl_is_configured() ? "^ssl:.*" : ".*")
+    re = (!re_ ? xstrdup(vconn_ssl_is_configured() ? "^ssl:.*" : "^tcp:.*")
           : re_[0] == '^' ? xstrdup(re_) : xasprintf("^%s", re_));
     regex = xmalloc(sizeof *regex);
     error = regcomp(regex, re, REG_NOSUB | REG_EXTENDED);

diff --git a/secchan/main.c b/secchan/main.c
index ca38576..c9cfc64 100644 (file)
--- a/secchan/main.c
+++ b/secchan/main.c
@@ -497,7 +497,8 @@ parse_options(int argc, char *argv[], struct ofsettings *s)
 
     /* Set accept_controller_regex. */
     if (!s->accept_controller_re) {
-        s->accept_controller_re = vconn_ssl_is_configured() ? "^ssl:.*" : ".*";
+        s->accept_controller_re
+            = vconn_ssl_is_configured() ? "^ssl:.*" : "^tcp:.*";
     }
 
     /* Mode of operation. */

diff --git a/secchan/secchan.8.in b/secchan/secchan.8.in
index b40842a..bbab7fb 100644 (file)
--- a/secchan/secchan.8.in
+++ b/secchan/secchan.8.in
@@ -182,8 +182,8 @@ names match the regular expression will be accepted.
 The default regular expression is \fBssl:.*\fR (meaning that only SSL
 controller connections will be accepted) when any of the SSL
 configuration options \fB--private-key\fR, \fB--certificate\fR, or
-\fB--ca-cert\fR is specified.  The default is \fB.*\fR otherwise
-(meaning that any controller will be accepted).
+\fB--ca-cert\fR is specified.  The default is \fB^tcp:.*\fR otherwise
+(meaning that only TCP controller connections will be accepted).
 
 The \fIregex\fR is implicitly anchored at the beginning of the
 controller location string, as if it begins with \fB^\fR.

diff --git a/utilities/ovs-discover.8.in b/utilities/ovs-discover.8.in
index d38ce9e..eb83a5f 100644 (file)
--- a/utilities/ovs-discover.8.in
+++ b/utilities/ovs-discover.8.in
@@ -28,15 +28,16 @@ itself to the background.
 .SH OPTIONS
 .TP
 \fB--accept-vconn=\fIregex\fR
-By default, \fBovs\-discover\fR accepts any controller location
-advertised over DHCP.  With this option, only controllers whose names
-match POSIX extended regular expression \fIregex\fR will be accepted.
-Specifying \fBssl:.*\fR for \fIregex\fR, for example, would cause only
-SSL controller connections to be accepted.
+With this option, only controllers whose names match POSIX extended
+regular expression \fIregex\fR will be accepted.  Specifying
+\fBssl:.*\fR for \fIregex\fR, for example, would cause only SSL
+controller connections to be accepted.
 
 The \fIregex\fR is implicitly anchored at the beginning of the
 controller location string, as if it begins with \fB^\fR.
 
+When this option is not given, the default \fIregex\fR is
+\fBtcp:.*\fR.
 .TP
 \fB--exit-without-bind\fR
 By default, \fBovs\-discover\fR binds the network device that receives

diff --git a/utilities/ovs-discover.c b/utilities/ovs-discover.c
index b664321..f47edc7 100644 (file)
--- a/utilities/ovs-discover.c
+++ b/utilities/ovs-discover.c
@@ -48,7 +48,7 @@ static int n_ifaces;
 
 /* --accept-vconn: Regular expression specifying the class of controller vconns
  * that we will accept during autodiscovery. */
-static const char *accept_controller_re = ".*";
+static const char *accept_controller_re = "tcp:.*";
 static regex_t accept_controller_regex;
 
 /* --exit-without-bind: Exit after discovering the controller, without binding

diff --git a/vswitchd/ovs-vswitchd.conf.5.in b/vswitchd/ovs-vswitchd.conf.5.in
index 81e007f..de0d6ea 100644 (file)
--- a/vswitchd/ovs-vswitchd.conf.5.in
+++ b/vswitchd/ovs-vswitchd.conf.5.in
@@ -410,8 +410,8 @@ the regular expression will be accepted.
 .IP
 The default regular expression is \fBssl:.*\fR, meaning that only SSL
 controller connections will be accepted, when SSL is configured (see
-\fBSSL Configuration\fR), and \fB.*\fR otherwise, meaning that any
-controller will be accepted.
+\fBSSL Configuration\fR), and \fBtcp:.*\fR otherwise, meaning that only
+TCP controller connections will be accepted.
 .IP
 The regular expression is implicitly anchored at the beginning of the
 controller location string, as if it begins with \fB^\fR.