commit afb6ff17390cb13780c6e813ad0535048dbd9d3c Author: Nick Mathewson nickm@torproject.org Date: Thu Aug 6 11:47:01 2020 -0400

Validate ed25519 keys and canonicity from circuit_n_conn_done()

Fixes bug 40080. Bugfix on 0.2.7.2-alpha. --- changes/bug40080 | 6 ++++++ src/core/or/channel.c | 2 +- src/core/or/channel.h | 3 +++ src/core/or/circuitbuild.c | 24 ++++++++++++++++++++---- 4 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/changes/bug40080 b/changes/bug40080 new file mode 100644 index 0000000000..8162466354 --- /dev/null +++ b/changes/bug40080 @@ -0,0 +1,6 @@ + o Minor bugfixes (security): + - When completing a channel, relays now check more thoroughly to make + sure that it matches any pending circuits before attaching those + circuits. Previously, address correctness and Ed25519 identities were not + checked in this case, but only when extending circuits on an existing + channel. Fixes bug 40080; bugfix on 0.2.7.2-alpha. diff --git a/src/core/or/channel.c b/src/core/or/channel.c index 3886906875..3bef6218ef 100644 --- a/src/core/or/channel.c +++ b/src/core/or/channel.c @@ -663,7 +663,7 @@ channel_find_by_global_id(uint64_t global_identifier)

/** Return true iff <b>chan</b> matches <b>rsa_id_digest</b> and <b>ed_id</b>. * as its identity keys. If either is NULL, do not check for a match. */ -static int +int channel_remote_identity_matches(const channel_t *chan, const char *rsa_id_digest, const ed25519_public_key_t *ed_id) diff --git a/src/core/or/channel.h b/src/core/or/channel.h index 97aa000337..4c0c9aeb4c 100644 --- a/src/core/or/channel.h +++ b/src/core/or/channel.h @@ -741,6 +741,9 @@ int channel_is_outgoing(channel_t *chan); void channel_mark_client(channel_t *chan); void channel_clear_client(channel_t *chan); int channel_matches_extend_info(channel_t *chan, extend_info_t *extend_info); +int channel_remote_identity_matches(const channel_t *chan, + const char *rsa_id_digest, + const ed25519_public_key_t *ed_id); int channel_matches_target_addr_for_extend(channel_t *chan, const tor_addr_t *target); unsigned int channel_num_circuits(channel_t *chan); diff --git a/src/core/or/circuitbuild.c b/src/core/or/circuitbuild.c index f3a5791d6c..67b47b38f1 100644 --- a/src/core/or/circuitbuild.c +++ b/src/core/or/circuitbuild.c @@ -623,21 +623,37 @@ circuit_n_chan_done(channel_t *chan, int status, int close_origin_circuits) circ->state != CIRCUIT_STATE_CHAN_WAIT) continue;

- if (tor_digest_is_zero(circ->n_hop->identity_digest)) { + const char *rsa_ident = NULL; + const ed25519_public_key_t *ed_ident = NULL; + if (! tor_digest_is_zero(circ->n_hop->identity_digest)) { + rsa_ident = circ->n_hop->identity_digest; + } + if (! ed25519_public_key_is_zero(&circ->n_hop->ed_identity)) { + ed_ident = &circ->n_hop->ed_identity; + } + + if (rsa_ident == NULL && ed_ident == NULL) { /* Look at addr/port. This is an unkeyed connection. */ if (!channel_matches_extend_info(chan, circ->n_hop)) continue; } else { - /* We expected a key. See if it's the right one. */ - if (tor_memneq(chan->identity_digest, - circ->n_hop->identity_digest, DIGEST_LEN)) + /* We expected a key or keys. See if they matched. */ + if (!channel_remote_identity_matches(chan, rsa_ident, ed_ident)) continue; + + /* If the channel is canonical, great. If not, it needs to match + * the requested address exactly. */ + if (! chan->is_canonical && + ! channel_matches_extend_info(chan, circ->n_hop)) { + continue; + } } if (!status) { /* chan failed; close circ */ log_info(LD_CIRC,"Channel failed; closing circ."); circuit_mark_for_close(circ, END_CIRC_REASON_CHANNEL_CLOSED); continue; } + if (close_origin_circuits && CIRCUIT_IS_ORIGIN(circ)) { log_info(LD_CIRC,"Channel deprecated for origin circs; closing circ."); circuit_mark_for_close(circ, END_CIRC_REASON_CHANNEL_CLOSED);