commit f9af7e8bd01d4b7a70776a96c649a89cf1717dd1 Author: teor teor2345@gmail.com Date: Wed Mar 1 16:23:02 2017 +1100

Accurately identify client connections by their lack of peer authentication

This means that we bail out earlier if asked to extend to a client.

Follow-up to 21407. Fixes bug 21406; bugfix on 0.2.4.23. --- changes/bug21406 | 5 +++++ src/or/channel.h | 4 ++-- src/or/channeltls.c | 4 ++++ src/or/command.c | 10 ++++++++-- 4 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/changes/bug21406 b/changes/bug21406 new file mode 100644 index 0000000..170e631 --- /dev/null +++ b/changes/bug21406 @@ -0,0 +1,5 @@ + o Minor bugfixes (code correctness): + - Accurately identify client connections using their lack of peer + authentication. This means that we bail out earlier if asked to extend + to a client. Follow-up to 21407. + Fixes bug 21406; bugfix on 0.2.4.23. diff --git a/src/or/channel.h b/src/or/channel.h index 26aa93b..748a099 100644 --- a/src/or/channel.h +++ b/src/or/channel.h @@ -214,8 +214,8 @@ struct channel_s { unsigned int is_bad_for_new_circs:1;

/** True iff we have decided that the other end of this connection - * is a client. Channels with this flag set should never be used - * to satisfy an EXTEND request. */ + * is a client or bridge relay. Connections with this flag set should never + * be used to satisfy an EXTEND request. */ unsigned int is_client:1;

/** Set if the channel was initiated remotely (came from a listener) */ diff --git a/src/or/channeltls.c b/src/or/channeltls.c index dbed95f..e734913 100644 --- a/src/or/channeltls.c +++ b/src/or/channeltls.c @@ -1654,6 +1654,10 @@ channel_tls_process_netinfo_cell(cell_t *cell, channel_tls_t *chan) tor_assert(tor_mem_is_zero( (const char*)(chan->conn->handshake_state-> authenticated_ed25519_peer_id.pubkey), 32)); + /* If the client never authenticated, it's a tor client or bridge + * relay, and we must not use it for EXTEND requests (nor could we, as + * there are no authenticated peer IDs) */ + channel_mark_client(TLS_CHAN_TO_BASE(chan)); channel_set_circid_type(TLS_CHAN_TO_BASE(chan), NULL, chan->conn->link_proto < MIN_LINK_PROTO_FOR_WIDE_CIRC_IDS);

diff --git a/src/or/command.c b/src/or/command.c index 5866c38..4d3830f 100644 --- a/src/or/command.c +++ b/src/or/command.c @@ -344,8 +344,14 @@ command_process_create_cell(cell_t *cell, channel_t *chan) int len; created_cell_t created_cell;

- /* Make sure we never try to use the OR connection on which we - * received this cell to satisfy an EXTEND request, */ + /* If the client used CREATE_FAST, it's probably a tor client or bridge + * relay, and we must not use it for EXTEND requests (in most cases, we + * won't have an authenticated peer ID for the extend). + * Public relays on 0.2.9 and later will use CREATE_FAST if they have no + * ntor onion key for this relay, but that should be a rare occurrence. + * Clients on 0.3.1 and later avoid using CREATE_FAST as much as they can, + * even during bootstrap, so the CREATE_FAST check is most accurate for + * earlier tor client versions. */ channel_mark_client(chan);

memset(&created_cell, 0, sizeof(created_cell));