Educate tor on OpenBSD's use of divert-to rules with the pf firewall.

This means that tor can run without needing to communicate with ioctls
to the firewall, and therefore doesn't need to run with privileges to
open the /dev/pf device node.

A new TransProxyType is added for this purpose, "pf-divert"; if the user
specifies this TransProxyType in their torrc, then the pf device node is
never opened and the connection destination is determined with getsockname
(as per pf(4)). The default behaviour (ie., when TransProxyType is "default"
when using the pf firewall) is still to assume that pf is configured with
rdr-to rules.

1 files changed, 7 insertions, 1 deletions

diff --git a/src/or/config.c b/src/or/config.c
index 55a23b1ce3..e22d3b86e0 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -1089,7 +1089,7 @@ options_act_reversible(const or_options_t *old_options, char **msg)
 
 #if defined(HAVE_NET_IF_H) && defined(HAVE_NET_PFVAR_H)
   /* Open /dev/pf before dropping privileges. */
-  if (options->TransPort_set && options->TransProxyType_parsed != TPT_IPFW) {
+  if (options->TransPort_set && options->TransProxyType_parsed == TPT_DEFAULT) {
     if (get_pf_socket() < 0) {
       *msg = tor_strdup("Unable to open /dev/pf for transparent proxy.");
       goto rollback;
@@ -2553,6 +2553,12 @@ options_validate(or_options_t *old_options, or_options_t *options,
   if (options->TransProxyType) {
     if (!strcasecmp(options->TransProxyType, "default")) {
       options->TransProxyType_parsed = TPT_DEFAULT;
+    } else if (!strcasecmp(options->TransProxyType, "pf-divert")) {
+#ifdef __linux__
+      REJECT("pf is a BSD-specific feature.");
+#else
+      options->TransProxyType_parsed = TPT_PF_DIVERT;
+#endif
     } else if (!strcasecmp(options->TransProxyType, "tproxy")) {
 #ifndef __linux__
       REJECT("TPROXY is a Linux-specific feature.");