[tor-commits] [tor/master] Ignore regular cells in padding circuits.
nickm at torproject.org
nickm at torproject.org
Mon Aug 5 15:11:17 UTC 2019
commit ce477da8a7969964810fb16502073d5f34e58692
Author: George Kadianakis <desnacked at riseup.net>
Date: Tue Jul 23 13:17:37 2019 +0300
Ignore regular cells in padding circuits.
Padding circuits were regular cells that got closed before their padding
machine could finish. This means that they can still receive regular cells from
their past life, but they have no way or reason to answer them anymore. Hence
let's ignore them before they even get to the proper subsystems.
---
scripts/maint/practracker/exceptions.txt | 6 +++---
src/core/or/circuitpadding.c | 37 ++++++++++++++++++++++++++++++++
src/core/or/circuitpadding.h | 4 ++++
src/core/or/relay.c | 25 ++++++---------------
4 files changed, 50 insertions(+), 22 deletions(-)
diff --git a/scripts/maint/practracker/exceptions.txt b/scripts/maint/practracker/exceptions.txt
index 642ae467f..d437726fe 100644
--- a/scripts/maint/practracker/exceptions.txt
+++ b/scripts/maint/practracker/exceptions.txt
@@ -84,7 +84,7 @@ problem function-size /src/core/or/circuitlist.c:circuit_about_to_free() 120
problem function-size /src/core/or/circuitlist.c:circuits_handle_oom() 117
problem function-size /src/core/or/circuitmux.c:circuitmux_set_policy() 109
problem function-size /src/core/or/circuitmux.c:circuitmux_attach_circuit() 113
-problem file-size /src/core/or/circuitpadding.c 3006
+problem file-size /src/core/or/circuitpadding.c 3043
problem function-size /src/core/or/circuitpadding.c:circpad_machine_schedule_padding() 107
problem function-size /src/core/or/circuitpadding_machines.c:circpad_machine_relay_hide_intro_circuits() 103
problem function-size /src/core/or/circuitpadding_machines.c:circpad_machine_client_hide_rend_circuits() 112
@@ -117,12 +117,12 @@ problem function-size /src/core/or/connection_or.c:connection_or_compute_authent
problem file-size /src/core/or/policies.c 3249
problem function-size /src/core/or/policies.c:policy_summarize() 107
problem function-size /src/core/or/protover.c:protover_all_supported() 117
-problem file-size /src/core/or/relay.c 3244
+problem file-size /src/core/or/relay.c 3263
problem function-size /src/core/or/relay.c:circuit_receive_relay_cell() 126
problem function-size /src/core/or/relay.c:relay_send_command_from_edge_() 109
problem function-size /src/core/or/relay.c:connection_ap_process_end_not_open() 192
problem function-size /src/core/or/relay.c:connection_edge_process_relay_cell_not_open() 137
-problem function-size /src/core/or/relay.c:connection_edge_process_relay_cell() 428
+problem function-size /src/core/or/relay.c:handle_relay_cell_command() 369
problem function-size /src/core/or/relay.c:connection_edge_package_raw_inbuf() 128
problem function-size /src/core/or/relay.c:circuit_resume_edge_reading_helper() 146
problem function-size /src/core/or/scheduler_kist.c:kist_scheduler_run() 171
diff --git a/src/core/or/circuitpadding.c b/src/core/or/circuitpadding.c
index 460f72c17..9ccad8744 100644
--- a/src/core/or/circuitpadding.c
+++ b/src/core/or/circuitpadding.c
@@ -1791,6 +1791,43 @@ circpad_cell_event_nonpadding_sent(circuit_t *on_circ)
} FOR_EACH_ACTIVE_CIRCUIT_MACHINE_END;
}
+/** Check if this cell or circuit are related to circuit padding and handle
+ * them if so. Return 0 if the cell was handled in this subsystem and does
+ * not need any other consideration, otherwise return 1.
+ */
+int
+circpad_check_received_cell(cell_t *cell, circuit_t *circ,
+ crypt_path_t *layer_hint,
+ const relay_header_t *rh)
+{
+ unsigned domain = layer_hint?LD_APP:LD_EXIT;
+
+ /* First handle the padding commands, since we want to ignore any other
+ * commands if this circuit is padding-specific. */
+ switch (rh->command) {
+ case RELAY_COMMAND_DROP:
+ /* Already examined in circpad_deliver_recognized_relay_cell_events */
+ return 0;
+ case RELAY_COMMAND_PADDING_NEGOTIATE:
+ circpad_handle_padding_negotiate(circ, cell);
+ return 0;
+ case RELAY_COMMAND_PADDING_NEGOTIATED:
+ if (circpad_handle_padding_negotiated(circ, cell, layer_hint) == 0)
+ circuit_read_valid_data(TO_ORIGIN_CIRCUIT(circ), rh->length);
+ return 0;
+ }
+
+ /* If this is a padding circuit we don't need to parse any other commands
+ * than the padding ones. Just drop them to the floor. */
+ if (circ->purpose == CIRCUIT_PURPOSE_C_CIRCUIT_PADDING) {
+ log_info(domain, "Ignored cell (%d) that arrived in padding circuit.",
+ rh->command);
+ return 0;
+ }
+
+ return 1;
+}
+
/**
* A "non-padding" cell has been received by this endpoint. React
* according to any padding state machines on the circuit.
diff --git a/src/core/or/circuitpadding.h b/src/core/or/circuitpadding.h
index fc2e595c0..e9eb32c61 100644
--- a/src/core/or/circuitpadding.h
+++ b/src/core/or/circuitpadding.h
@@ -734,6 +734,10 @@ bool circpad_padding_negotiated(struct circuit_t *circ,
circpad_purpose_mask_t circpad_circ_purpose_to_mask(uint8_t circ_purpose);
+int circpad_check_received_cell(cell_t *cell, circuit_t *circ,
+ crypt_path_t *layer_hint,
+ const relay_header_t *rh);
+
MOCK_DECL(circpad_decision_t,
circpad_machine_schedule_padding,(circpad_machine_runtime_t *));
diff --git a/src/core/or/relay.c b/src/core/or/relay.c
index 84fc58787..3b5aa2b66 100644
--- a/src/core/or/relay.c
+++ b/src/core/or/relay.c
@@ -1596,28 +1596,15 @@ handle_relay_command(cell_t *cell, circuit_t *circ,
tor_assert(rh);
- switch (rh->command) {
- case RELAY_COMMAND_DROP:
- /* Already examined in circpad_deliver_recognized_relay_cell_events */
- return 0;
- case RELAY_COMMAND_PADDING_NEGOTIATE:
- circpad_handle_padding_negotiate(circ, cell);
- return 0;
- case RELAY_COMMAND_PADDING_NEGOTIATED:
- if (circpad_handle_padding_negotiated(circ, cell, layer_hint) == 0)
- circuit_read_valid_data(TO_ORIGIN_CIRCUIT(circ), rh->length);
- return 0;
- }
-
- /* If this is a padding circuit we don't need to parse any other commands
- * than the padding ones. Just drop them to the floor. */
- if (circ->purpose == CIRCUIT_PURPOSE_C_CIRCUIT_PADDING) {
- log_info(domain, "Ignored cell (%d) that arrived in padding circuit.",
- rh.command);
+ /* First pass the cell to the circuit padding subsystem, in case it's a
+ * padding cell or circuit that should be handled there. */
+ if (circpad_check_received_cell(cell, circ, layer_hint, rh) == 0) {
+ log_debug(domain, "Cell handled as circuit padding");
return 0;
}
- switch (rh.command) {
+ /* Now handle all the other commands */
+ switch (rh->command) {
case RELAY_COMMAND_BEGIN:
case RELAY_COMMAND_BEGIN_DIR:
if (layer_hint &&
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