From ce3af5dd5948cd9c24fc5b5f70814b38cbca46a9 Mon Sep 17 00:00:00 2001 From: David Goulet Date: Mon, 1 Feb 2021 08:56:27 -0500 Subject: relay: Follow consensus parameter for network reentry Obey the "allow-network-reentry" consensus parameters in order to decide to allow it or not at the Exit. Closes #40268 Signed-off-by: David Goulet --- src/core/or/connection_edge.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/src/core/or/connection_edge.c b/src/core/or/connection_edge.c index f9a9bbdb73..b40fa3e567 100644 --- a/src/core/or/connection_edge.c +++ b/src/core/or/connection_edge.c @@ -4003,6 +4003,15 @@ my_exit_policy_rejects(const tor_addr_t *addr, return 0; } +/** Return true iff the consensus allows network reentry. The default value is + * false if the parameter is not found. */ +static bool +network_reentry_is_allowed(void) +{ + /* Default is false, re-entry is not allowed. */ + return !!networkstatus_get_param(NULL, "allow-network-reentry", 0, 0, 1); +} + /** Connect to conn's specified addr and port. If it worked, conn * has now been added to the connection_array. * @@ -4040,6 +4049,8 @@ connection_exit_connect(edge_connection_t *edge_conn) * infinite-length circuits (see "A Practical Congestion Attack on Tor Using * Long Paths", Usenix Security 2009). See also ticket 2667. * + * Skip this if the network reentry is allowed (known from the consensus). + * * The TORPROTOCOL reason is used instead of EXITPOLICY so client do NOT * attempt to retry connecting onto another circuit that will also fail * bringing considerable more load on the network if so. @@ -4050,6 +4061,7 @@ connection_exit_connect(edge_connection_t *edge_conn) * reason that makes the client retry results in much worst consequences in * case of an attack so this is a small price to pay. */ if (!connection_edge_is_rendezvous_stream(edge_conn) && + !network_reentry_is_allowed() && nodelist_reentry_probably_contains(&conn->addr, conn->port)) { log_info(LD_EXIT, "%s:%d tried to connect back to a known relay address. " "Closing.", escaped_safe_str_client(conn->address), -- cgit v1.2.3-54-g00ecf From 98590621bb49cbecd601085f7e03697f8783ff7b Mon Sep 17 00:00:00 2001 From: David Goulet Date: Mon, 1 Feb 2021 09:04:50 -0500 Subject: relay: Double the size of the relay reentry set This is to minimize false positive and thus deny reentry to Exit connections that were in reality not re-entering. Helps with overall UX. Signed-off-by: David Goulet --- src/feature/nodelist/nodelist.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/src/feature/nodelist/nodelist.c b/src/feature/nodelist/nodelist.c index 9d553ce1f5..22b93762e7 100644 --- a/src/feature/nodelist/nodelist.c +++ b/src/feature/nodelist/nodelist.c @@ -672,8 +672,12 @@ nodelist_set_consensus(networkstatus_t *ns) address_set_free(the_nodelist->node_addrs); addr_port_set_free(the_nodelist->reentry_set); the_nodelist->node_addrs = address_set_new(estimated_addresses); - /* Times two here is for both the ORPort and DirPort. */ - the_nodelist->reentry_set = addr_port_set_new(estimated_addresses * 2); + /* Times two here is for both the ORPort and DirPort. We double it again in + * order to minimize as much as possible the false positive when looking up + * this set. Reason is that Exit streams that are legitimate but end up a + * false positive against this set will thus be considered reentry and be + * rejected which means a bad UX. */ + the_nodelist->reentry_set = addr_port_set_new(estimated_addresses * 2 * 2); SMARTLIST_FOREACH_BEGIN(ns->routerstatus_list, routerstatus_t *, rs) { node_t *node = node_get_or_create(rs->identity_digest); -- cgit v1.2.3-54-g00ecf