commit 6ab07419c88e35c6d8610e20fb3cea16e39c8acd Author: David Goulet dgoulet@torproject.org Date: Tue Nov 28 19:02:00 2017 -0500

Use local descriptor object to exclude self in path selection

TROVE-2017-12. Severity: Medium

When choosing a random node for a circuit, directly use our router descriptor to exclude ourself instead of the one in the global descriptor list. That list could be empty because tor could be downloading them which could lead to not excluding ourself.

Closes #21534 --- changes/trove-2017-012-part1 | 6 ++++++ src/or/routerlist.c | 5 ++++- 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/changes/trove-2017-012-part1 b/changes/trove-2017-012-part1 new file mode 100644 index 000000000..9fccc2cf6 --- /dev/null +++ b/changes/trove-2017-012-part1 @@ -0,0 +1,6 @@ + o Major bugfixes (security, relay): + - When running as a relay, make sure that we never build a path through + ourselves, even in the case where we have somehow lost the version of + our descriptor appearing in the consensus. Fixes part of bug 21534; + bugfix on 0.2.0.1-alpha. This issue is also tracked as TROVE-2017-012 + and CVE-2017-8822. diff --git a/src/or/routerlist.c b/src/or/routerlist.c index 07e87724b..3bf1eb895 100644 --- a/src/or/routerlist.c +++ b/src/or/routerlist.c @@ -2411,7 +2411,10 @@ router_choose_random_node(smartlist_t *excludedsmartlist, }); }

- if ((r = routerlist_find_my_routerinfo())) + /* If the node_t is not found we won't be to exclude ourself but we + * won't be able to pick ourself in router_choose_random_node() so + * this is fine to at least try with our routerinfo_t object. */ + if ((r = router_get_my_routerinfo())) routerlist_add_node_and_family(excludednodes, r);

router_add_running_nodes_to_smartlist(sl, allow_invalid,