From 6fcae8e0d080d7d0875eab4a0118e8fdaf5e832c Mon Sep 17 00:00:00 2001 From: David Goulet Date: Tue, 2 Aug 2022 15:49:03 -0400 Subject: relay: Don't send DESTROY remote reason backward or forward Fixes #40649 Signed-off-by: David Goulet --- src/core/or/command.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'src/core') diff --git a/src/core/or/command.c b/src/core/or/command.c index 65853f7844..a8b93dc9a0 100644 --- a/src/core/or/command.c +++ b/src/core/or/command.c @@ -629,9 +629,11 @@ command_process_destroy_cell(cell_t *cell, channel_t *chan) if (!CIRCUIT_IS_ORIGIN(circ) && chan == TO_OR_CIRCUIT(circ)->p_chan && cell->circ_id == TO_OR_CIRCUIT(circ)->p_circ_id) { - /* the destroy came from behind */ + /* The destroy came from behind so nullify its p_chan. Close the circuit + * with a DESTROYED reason so we don't propagate along the path forward the + * reason which could be used as a side channel. */ circuit_set_p_circid_chan(TO_OR_CIRCUIT(circ), 0, NULL); - circuit_mark_for_close(circ, reason|END_CIRC_REASON_FLAG_REMOTE); + circuit_mark_for_close(circ, END_CIRC_REASON_DESTROYED); } else { /* the destroy came from ahead */ circuit_set_n_circid_chan(circ, 0, NULL); if (CIRCUIT_IS_ORIGIN(circ)) { @@ -639,9 +641,10 @@ command_process_destroy_cell(cell_t *cell, channel_t *chan) } else { /* Close the circuit so we stop queuing cells for it and propagate the * DESTROY cell down the circuit so relays can stop queuing in-flight - * cells for this circuit which helps with memory pressure. */ + * cells for this circuit which helps with memory pressure. We do NOT + * propagate the remote reason so not to create a side channel. */ log_debug(LD_OR, "Received DESTROY cell from n_chan, closing circuit."); - circuit_mark_for_close(circ, reason | END_CIRC_REASON_FLAG_REMOTE); + circuit_mark_for_close(circ, END_CIRC_REASON_DESTROYED); } } } -- cgit v1.2.3-54-g00ecf