[tor-commits] [tor/master] Educate tor on OpenBSD's use of divert-to rules with the pf firewall.
nickm at torproject.org
nickm at torproject.org
Thu Apr 17 03:05:25 UTC 2014
commit f680d0fdd2e42bce109219ed78d0527d16995415
Author: dana koch <dsk at google.com>
Date: Mon Feb 10 21:23:51 2014 +1100
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.
---
doc/tor.1.txt | 17 ++++++++----
src/or/config.c | 8 +++++-
src/or/connection_edge.c | 64 ++++++++++++++++++++++++++++++++++++----------
src/or/or.h | 7 ++++-
4 files changed, 76 insertions(+), 20 deletions(-)
diff --git a/doc/tor.1.txt b/doc/tor.1.txt
index 1a5ced8..d1556a5 100644
--- a/doc/tor.1.txt
+++ b/doc/tor.1.txt
@@ -1196,12 +1196,12 @@ The following options are useful only for clients (that is, if
compatibility, TransListenAddress is only allowed when TransPort is just
a port number.)
-[[TransProxyType]] **TransProxyTYpe** **default**|**TPROXY**|**ipfw**::
+[[TransProxyType]] **TransProxyTYpe** **default**|**TPROXY**|**ipfw**|**pf-divert**::
TransProxyType may only be enabled when there is transparent proxy listener
enabled.
+
- Set this to TPROXY if you wish to be able to use the TPROXY Linux module to
- transparently proxy connections that are configured using the TransPort
+ Set this to "TPROXY" if you wish to be able to use the TPROXY Linux module
+ to transparently proxy connections that are configured using the TransPort
option. This setting lets the listener on the TransPort accept connections
for all addresses, even when the TransListenAddress is configured for an
internal address. Detailed information on how to configure the TPROXY
@@ -1210,8 +1210,15 @@ The following options are useful only for clients (that is, if
+
Set this option to "ipfw" to use the FreeBSD ipfw interface.
+
- Set this option to "default", or leave it unconfigured, to use regular
- IPTables on Linux, or to use pf on the *BSD operating systems.
+ On *BSD operating systems when using pf, set this to "pf-divert" to take
+ advantage of +divert-to+ rules, which do not modify the packets like
+ +rdr-to+ rules do. Detailed information on how to configure pf to use
+ +divert-to+ rules can be found in the pf.conf(5) manual page. On OpenBSD,
+ +divert-to+ is available to use on versions greater than or equal to
+ OpenBSD 4.4.
+ +
+ Set this to "default", or leave it unconfigured, to use regular IPTables
+ on Linux, or to use pf +rdr-to+ rules on *BSD systems.
+
(Default: "default".)
diff --git a/src/or/config.c b/src/or/config.c
index 55a23b1..e22d3b8 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.");
diff --git a/src/or/connection_edge.c b/src/or/connection_edge.c
index 2ece2e4..04e60b9 100644
--- a/src/or/connection_edge.c
+++ b/src/or/connection_edge.c
@@ -1391,35 +1391,43 @@ get_pf_socket(void)
}
#endif
-/** Fetch the original destination address and port from a
- * system-specific interface and put them into a
- * socks_request_t as if they came from a socks request.
- *
- * Return -1 if an error prevents fetching the destination,
- * else return 0.
- */
-static int
-connection_ap_get_original_destination(entry_connection_t *conn,
- socks_request_t *req)
+static int
+destination_from_socket(entry_connection_t *conn, socks_request_t *req)
{
-#ifdef TRANS_NETFILTER
- /* Linux 2.4+ */
struct sockaddr_storage orig_dst;
socklen_t orig_dst_len = sizeof(orig_dst);
tor_addr_t addr;
+#ifdef TRANS_NETFILTER
if (getsockopt(ENTRY_TO_CONN(conn)->s, SOL_IP, SO_ORIGINAL_DST,
(struct sockaddr*)&orig_dst, &orig_dst_len) < 0) {
int e = tor_socket_errno(ENTRY_TO_CONN(conn)->s);
log_warn(LD_NET, "getsockopt() failed: %s", tor_socket_strerror(e));
return -1;
}
+#elif defined(TRANS_PF)
+ if (getsockname(ENTRY_TO_CONN(conn)->s, (struct sockaddr*)&orig_dst,
+ &orig_dst_len) < 0) {
+ int e = tor_socket_errno(ENTRY_TO_CONN(conn)->s);
+ log_warn(LD_NET, "getsockname() failed: %s", tor_socket_strerror(e));
+ return -1;
+ }
+#else
+ (void)conn;
+ (void)req;
+ log_warn(LD_BUG, "Unable to determine destination from socket.");
+ return -1;
+#endif
tor_addr_from_sockaddr(&addr, (struct sockaddr*)&orig_dst, &req->port);
tor_addr_to_str(req->address, &addr, sizeof(req->address), 1);
return 0;
-#elif defined(TRANS_PF)
+}
+
+static int
+destination_from_pf(entry_connection_t *conn, socks_request_t *req)
+{
struct sockaddr_storage proxy_addr;
socklen_t proxy_addr_len = sizeof(proxy_addr);
struct sockaddr *proxy_sa = (struct sockaddr*) &proxy_addr;
@@ -1496,6 +1504,36 @@ connection_ap_get_original_destination(entry_connection_t *conn,
req->port = ntohs(pnl.rdport);
return 0;
+}
+
+
+/** Fetch the original destination address and port from a
+ * system-specific interface and put them into a
+ * socks_request_t as if they came from a socks request.
+ *
+ * Return -1 if an error prevents fetching the destination,
+ * else return 0.
+ */
+static int
+connection_ap_get_original_destination(entry_connection_t *conn,
+ socks_request_t *req)
+{
+#ifdef TRANS_NETFILTER
+ return destination_from_socket(conn, req);
+#elif defined(TRANS_PF)
+ const or_options_t *options = get_options();
+
+ if (options->TransProxyType_parsed == TPT_PF_DIVERT)
+ return destination_from_socket(conn, req);
+
+ if (options->TransProxyType_parsed == TPT_DEFAULT)
+ return destination_from_pf(conn, req);
+
+ (void)conn;
+ (void)req;
+ log_warn(LD_BUG, "Proxy destination determination mechanism %s unknown.",
+ options->TransProxyType);
+ return -1;
#else
(void)conn;
(void)req;
diff --git a/src/or/or.h b/src/or/or.h
index a5e2e70..5510af7 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -3461,7 +3461,12 @@ typedef struct {
const char *TransProxyType; /**< What kind of transparent proxy
* implementation are we using? */
/** Parsed value of TransProxyType. */
- enum { TPT_DEFAULT, TPT_TPROXY, TPT_IPFW } TransProxyType_parsed;
+ enum {
+ TPT_DEFAULT,
+ TPT_PF_DIVERT,
+ TPT_IPFW,
+ TPT_TPROXY,
+ } TransProxyType_parsed;
config_line_t *NATDPort_lines; /**< Ports to listen on for transparent natd
* connections. */
config_line_t *ControlPort_lines; /**< Ports to listen on for control
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