[tor-commits] [tor/master] hs-v3: Parse ESTABLISH_INTRO cell extension
nickm at torproject.org
nickm at torproject.org
Mon Sep 9 16:35:37 UTC 2019
commit 724d9eb84be4c9a8b6cd34f08dc7b5d00f69f09e
Author: David Goulet <dgoulet at torproject.org>
Date: Mon Aug 12 13:34:09 2019 -0400
hs-v3: Parse ESTABLISH_INTRO cell extension
Signed-off-by: David Goulet <dgoulet at torproject.org>
---
src/core/or/or_circuit_st.h | 4 ++
src/feature/hs/hs_intropoint.c | 122 +++++++++++++++++++++++++++++++++++++++--
2 files changed, 121 insertions(+), 5 deletions(-)
diff --git a/src/core/or/or_circuit_st.h b/src/core/or/or_circuit_st.h
index 8f319585a..f3eb86161 100644
--- a/src/core/or/or_circuit_st.h
+++ b/src/core/or/or_circuit_st.h
@@ -72,6 +72,10 @@ struct or_circuit_t {
* buffer stats to disk. */
uint64_t total_cell_waiting_time;
+ /** If set, the DoS defenses are enabled on this circuit meaning that the
+ * introduce2_bucket is initialized and used. */
+ unsigned int introduce2_dos_defense_enabled : 1;
+
/** INTRODUCE2 cell bucket controlling how much can go on this circuit. Only
* used if this is a service introduction circuit at the intro point
* (purpose = CIRCUIT_PURPOSE_INTRO_POINT). */
diff --git a/src/feature/hs/hs_intropoint.c b/src/feature/hs/hs_intropoint.c
index a53ca0d6b..bafd3d1f4 100644
--- a/src/feature/hs/hs_intropoint.c
+++ b/src/feature/hs/hs_intropoint.c
@@ -26,6 +26,7 @@
#include "feature/hs/hs_circuitmap.h"
#include "feature/hs/hs_common.h"
+#include "feature/hs/hs_config.h"
#include "feature/hs/hs_descriptor.h"
#include "feature/hs/hs_dos.h"
#include "feature/hs/hs_intropoint.h"
@@ -181,6 +182,110 @@ hs_intro_send_intro_established_cell,(or_circuit_t *circ))
return ret;
}
+static void
+handle_establish_intro_cell_dos_extension(
+ const trn_cell_extension_field_t *field,
+ or_circuit_t *circ)
+{
+ ssize_t ret;
+ uint64_t intro2_rate_per_sec = 0, intro2_burst_per_sec = 0;
+ trn_cell_extension_dos_t *dos = NULL;
+
+ tor_assert(field);
+ tor_assert(circ);
+
+ ret = trn_cell_extension_dos_parse(&dos,
+ trn_cell_extension_field_getconstarray_field(field),
+ trn_cell_extension_field_getlen_field(field));
+ if (ret < 0) {
+ goto end;
+ }
+
+ for (size_t i = 0; i < trn_cell_extension_dos_get_n_params(dos); i++) {
+ const trn_cell_extension_dos_param_t *param =
+ trn_cell_extension_dos_getconst_params(dos, i);
+ if (BUG(param == NULL)) {
+ goto end;
+ }
+
+ switch (trn_cell_extension_dos_param_get_type(param)) {
+ case TRUNNEL_DOS_PARAM_TYPE_INTRO2_RATE_PER_SEC:
+ intro2_rate_per_sec = trn_cell_extension_dos_param_get_value(param);
+ break;
+ case TRUNNEL_DOS_PARAM_TYPE_INTRO2_BURST_PER_SEC:
+ intro2_burst_per_sec = trn_cell_extension_dos_param_get_value(param);
+ break;
+ default:
+ goto end;
+ }
+ }
+
+ /* Validation. A value of 0 on either of them means the defenses are
+ * disabled so we ignore. */
+ if ((intro2_rate_per_sec > HS_CONFIG_V3_DOS_DEFENSE_BURST_PER_SEC_MAX ||
+ intro2_rate_per_sec <= HS_CONFIG_V3_DOS_DEFENSE_RATE_PER_SEC_MIN) ||
+ (intro2_burst_per_sec > HS_CONFIG_V3_DOS_DEFENSE_RATE_PER_SEC_MAX ||
+ intro2_burst_per_sec <= HS_CONFIG_V3_DOS_DEFENSE_BURST_PER_SEC_MIN) ||
+ (intro2_burst_per_sec < intro2_rate_per_sec)) {
+ circ->introduce2_dos_defense_enabled = 0;
+ log_info(LD_REND, "Intro point DoS defenses disabled due to bad values");
+ } else {
+ circ->introduce2_dos_defense_enabled = 1;
+
+ /* Initialize the INTRODUCE2 token bucket for the rate limiting. */
+ token_bucket_ctr_init(&circ->introduce2_bucket,
+ (uint32_t) intro2_rate_per_sec,
+ (uint32_t) intro2_burst_per_sec,
+ (uint32_t) approx_time());
+ log_debug(LD_REND, "Intro point DoS defenses enabled. Rate is %" PRIu64
+ " and Burst is %" PRIu64, intro2_rate_per_sec,
+ intro2_burst_per_sec);
+ }
+
+ end:
+ trn_cell_extension_dos_free(dos);
+ return;
+}
+
+static void
+handle_establish_intro_cell_extensions(
+ const trn_cell_establish_intro_t *parsed_cell,
+ or_circuit_t *circ)
+{
+ const trn_cell_extension_t *extensions;
+
+ tor_assert(parsed_cell);
+ tor_assert(circ);
+
+ extensions = trn_cell_establish_intro_getconst_extensions(parsed_cell);
+ if (extensions == NULL) {
+ goto end;
+ }
+
+ /* Go over all extensions. */
+ for (size_t idx = 0; idx < trn_cell_extension_get_num(extensions); idx++) {
+ const trn_cell_extension_field_t *field =
+ trn_cell_extension_getconst_fields(extensions, idx);
+ if (BUG(field == NULL)) {
+ /* The number of extensions should match the number of fields. */
+ break;
+ }
+
+ switch (trn_cell_extension_field_get_field_type(field)) {
+ case TRUNNEL_CELL_EXTENSION_TYPE_DOS:
+ /* After this, the circuit should be set for DoS defenses. */
+ handle_establish_intro_cell_dos_extension(field, circ);
+ break;
+ default:
+ /* Unknown extension. Skip over. */
+ break;
+ }
+ }
+
+ end:
+ return;
+}
+
/** We received an ESTABLISH_INTRO <b>parsed_cell</b> on <b>circ</b>. It's
* well-formed and passed our verifications. Perform appropriate actions to
* establish an intro point. */
@@ -193,6 +298,18 @@ handle_verified_establish_intro_cell(or_circuit_t *circ,
get_auth_key_from_cell(&auth_key, RELAY_COMMAND_ESTABLISH_INTRO,
parsed_cell);
+ /* Initialize the INTRODUCE2 token bucket for the DoS defenses using the
+ * consensus/default values. We might get a cell extension that changes
+ * those but if we don't, the default or consensus parameters are used. */
+ circ->introduce2_dos_defense_enabled = hs_dos_get_intro2_enabled_param();
+ token_bucket_ctr_init(&circ->introduce2_bucket,
+ hs_dos_get_intro2_rate_param(),
+ hs_dos_get_intro2_burst_param(),
+ (uint32_t) approx_time());
+
+ /* Handle cell extension if any. */
+ handle_establish_intro_cell_extensions(parsed_cell, circ);
+
/* Then notify the hidden service that the intro point is established by
sending an INTRO_ESTABLISHED cell */
if (hs_intro_send_intro_established_cell(circ)) {
@@ -204,11 +321,6 @@ handle_verified_establish_intro_cell(or_circuit_t *circ,
hs_circuitmap_register_intro_circ_v3_relay_side(circ, &auth_key);
/* Repurpose this circuit into an intro circuit. */
circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_INTRO_POINT);
- /* Initialize the INTRODUCE2 token bucket for the rate limiting. */
- token_bucket_ctr_init(&circ->introduce2_bucket,
- hs_dos_get_intro2_rate_param(),
- hs_dos_get_intro2_burst_param(),
- (uint32_t) approx_time());
return 0;
}
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