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[tor-commits] [tor/master] Add "HiddenServiceMaxStreams" as a per-HS tunable.
commit db7bde08be59398488624bc377d1d5318182ee45
Author: Yawning Angel <yawning@xxxxxxxxxxxxxxx>
Date: Wed May 20 17:33:59 2015 +0000
Add "HiddenServiceMaxStreams" as a per-HS tunable.
When set, this limits the maximum number of simultaneous streams per
rendezvous circuit on the server side of a HS, with further RELAY_BEGIN
cells being silently ignored.
This can be modified via "HiddenServiceMaxStreamsCloseCircuit", which
if set will cause offending rendezvous circuits to be torn down instead.
Addresses part of #16052.
---
changes/feature16052 | 5 +++++
doc/tor.1.txt | 10 +++++++++
src/or/circuituse.c | 27 ++++++++++++++++-------
src/or/config.c | 2 ++
src/or/connection_edge.c | 2 ++
src/or/or.h | 3 +++
src/or/rendservice.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++
7 files changed, 94 insertions(+), 8 deletions(-)
diff --git a/changes/feature16052 b/changes/feature16052
new file mode 100644
index 0000000..cd09b58
--- /dev/null
+++ b/changes/feature16052
@@ -0,0 +1,5 @@
+ o Minor features (hidden service):
+ - Add the new options "HiddenServiceMaxStreams" and
+ "HiddenServiceMaxStreamsCloseCircuit" to allow hidden services to limit
+ the maximum number of simultaneous streams per circuit, and optionally
+ tear down the circuit when the limit is exceeded. Part of ticket 16052.
diff --git a/doc/tor.1.txt b/doc/tor.1.txt
index 2bb5f94..13f2bdd 100644
--- a/doc/tor.1.txt
+++ b/doc/tor.1.txt
@@ -2149,6 +2149,16 @@ The following options are used to configure a hidden service.
not an authorization mechanism; it is instead meant to be a mild
inconvenience to port-scanners.) (Default: 0)
+[[HiddenServiceMaxStreams]] **HiddenServiceMaxStreams** __N__::
+ The maximum number of simultaneous streams (connections) per rendezvous
+ circuit. (Setting this to 0 will allow an unlimited number of simultanous
+ streams.) (Default: 0)
+
+[[HiddenServiceMaxStreamsCloseCircuit]] **HiddenServiceMaxStreamsCloseCircuit** **0**|**1**::
+ If set to 1, then exceeding **HiddenServiceMaxStreams** will cause the
+ offending rendezvous circuit to be torn down, as opposed to stream creation
+ requests that exceed the limit being silently ignored. (Default: 0)
+
[[RendPostPeriod]] **RendPostPeriod** __N__ **seconds**|**minutes**|**hours**|**days**|**weeks**::
Every time the specified period elapses, Tor uploads any rendezvous
service descriptors to the directory servers. This information is also
diff --git a/src/or/circuituse.c b/src/or/circuituse.c
index b54a4d2..a429a7d 100644
--- a/src/or/circuituse.c
+++ b/src/or/circuituse.c
@@ -1189,17 +1189,28 @@ circuit_detach_stream(circuit_t *circ, edge_connection_t *conn)
if (CIRCUIT_IS_ORIGIN(circ)) {
origin_circuit_t *origin_circ = TO_ORIGIN_CIRCUIT(circ);
+ int removed = 0;
if (conn == origin_circ->p_streams) {
origin_circ->p_streams = conn->next_stream;
- return;
+ removed = 1;
+ } else {
+ for (prevconn = origin_circ->p_streams;
+ prevconn && prevconn->next_stream && prevconn->next_stream != conn;
+ prevconn = prevconn->next_stream)
+ ;
+ if (prevconn && prevconn->next_stream) {
+ prevconn->next_stream = conn->next_stream;
+ removed = 1;
+ }
}
-
- for (prevconn = origin_circ->p_streams;
- prevconn && prevconn->next_stream && prevconn->next_stream != conn;
- prevconn = prevconn->next_stream)
- ;
- if (prevconn && prevconn->next_stream) {
- prevconn->next_stream = conn->next_stream;
+ if (removed) {
+ /* If the stream was removed, and it was a rend stream, decrement the
+ * number of streams on the circuit associated with the rend service.
+ */
+ if (circ->purpose == CIRCUIT_PURPOSE_S_REND_JOINED) {
+ tor_assert(origin_circ->rend_data);
+ origin_circ->rend_data->nr_streams--;
+ }
return;
}
} else {
diff --git a/src/or/config.c b/src/or/config.c
index 1030448..1c04578 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -286,6 +286,8 @@ static config_var_t option_vars_[] = {
VAR("HiddenServiceVersion",LINELIST_S, RendConfigLines, NULL),
VAR("HiddenServiceAuthorizeClient",LINELIST_S,RendConfigLines, NULL),
VAR("HiddenServiceAllowUnknownPorts",LINELIST_S, RendConfigLines, NULL),
+ VAR("HiddenServiceMaxStreams",LINELIST_S, RendConfigLines, NULL),
+ VAR("HiddenServiceMaxStreamsCloseCircuit",LINELIST_S, RendConfigLines, NULL),
V(HiddenServiceStatistics, BOOL, "0"),
V(HidServAuth, LINELIST, NULL),
V(CloseHSClientCircuitsImmediatelyOnTimeout, BOOL, "0"),
diff --git a/src/or/connection_edge.c b/src/or/connection_edge.c
index cc6e3d7..c63c350 100644
--- a/src/or/connection_edge.c
+++ b/src/or/connection_edge.c
@@ -2860,6 +2860,8 @@ connection_exit_begin_conn(cell_t *cell, circuit_t *circ)
origin_circ->p_streams = n_stream;
assert_circuit_ok(circ);
+ origin_circ->rend_data->nr_streams++;
+
connection_exit_connect(n_stream);
/* For path bias: This circuit was used successfully */
diff --git a/src/or/or.h b/src/or/or.h
index 5bb080f..af34967 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -818,6 +818,9 @@ typedef struct rend_data_t {
/** List of HSDir fingerprints on which this request has been sent to.
* This contains binary identity digest of the directory. */
smartlist_t *hsdirs_fp;
+
+ /** Number of streams associated with this rendezvous circuit. */
+ int nr_streams;
} rend_data_t;
/** Time interval for tracking replays of DH public keys received in
diff --git a/src/or/rendservice.c b/src/or/rendservice.c
index daca4cc..5d2225e 100644
--- a/src/or/rendservice.c
+++ b/src/or/rendservice.c
@@ -147,6 +147,13 @@ typedef struct rend_service_t {
/** If true, we don't close circuits for making requests to unsupported
* ports. */
int allow_unknown_ports;
+ /** The maximum number of simultanious streams-per-circuit that are allowed
+ * to be established, or 0 if no limit is set.
+ */
+ int max_streams_per_circuit;
+ /** If true, we close circuits that exceed the max_streams_per_circuit
+ * limit. */
+ int max_streams_close_circuit;
} rend_service_t;
/** Returns a escaped string representation of the service, <b>s</b>.
@@ -539,6 +546,33 @@ rend_config_services(const or_options_t *options, int validate_only)
log_info(LD_CONFIG,
"HiddenServiceDirGroupReadable=%d for %s",
service->dir_group_readable, service->directory);
+ } else if (!strcasecmp(line->key, "HiddenServiceMaxStreams")) {
+ service->max_streams_per_circuit = (int)tor_parse_long(line->value,
+ 10, 0, 65535, &ok, NULL);
+ if (!ok) {
+ log_warn(LD_CONFIG,
+ "HiddenServiceMaxStreams should be between 0 and %d, not %s",
+ 65535, line->value);
+ rend_service_free(service);
+ return -1;
+ }
+ log_info(LD_CONFIG,
+ "HiddenServiceMaxStreams=%d for %s",
+ service->max_streams_per_circuit, service->directory);
+ } else if (!strcasecmp(line->key, "HiddenServiceMaxStreamsCloseCircuit")) {
+ service->max_streams_close_circuit = (int)tor_parse_long(line->value,
+ 10, 0, 1, &ok, NULL);
+ if (!ok) {
+ log_warn(LD_CONFIG,
+ "HiddenServiceMaxStreamsCloseCircuit should be 0 or 1, not %s",
+ line->value);
+ rend_service_free(service);
+ return -1;
+ }
+ log_info(LD_CONFIG,
+ "HiddenServiceMaxStreamsCloseCircuit=%d for %s",
+ (int)service->max_streams_close_circuit, service->directory);
+
} else if (!strcasecmp(line->key, "HiddenServiceAuthorizeClient")) {
/* Parse auth type and comma-separated list of client names and add a
* rend_authorized_client_t for each client to the service's list
@@ -3795,6 +3829,25 @@ rend_service_set_connection_addr_port(edge_connection_t *conn,
serviceid, (unsigned)circ->base_.n_circ_id);
return -2;
}
+ if (service->max_streams_per_circuit > 0) {
+ /* Enforce the streams-per-circuit limit, and refuse to provide a
+ * mapping if this circuit will exceed the limit. */
+#define MAX_STREAM_WARN_INTERVAL 600
+ static struct ratelim_t stream_ratelim =
+ RATELIM_INIT(MAX_STREAM_WARN_INTERVAL);
+ if (circ->rend_data->nr_streams >= service->max_streams_per_circuit) {
+ log_fn_ratelim(&stream_ratelim, LOG_WARN, LD_REND,
+ "Maximum streams per circuit limit reached on rendezvous "
+ "circuit %u; %s. Circuit has %d out of %d streams.",
+ (unsigned)circ->base_.n_circ_id,
+ service->max_streams_close_circuit ?
+ "closing circuit" :
+ "ignoring open stream request",
+ circ->rend_data->nr_streams,
+ service->max_streams_per_circuit);
+ return service->max_streams_close_circuit ? -2 : -1;
+ }
+ }
matching_ports = smartlist_new();
SMARTLIST_FOREACH(service->ports, rend_service_port_config_t *, p,
{
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