tor-commits May 2018

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1514 discussions

[tor/master] Avoid unsigned integer underflow on empty input.
by nickm＠torproject.org 08 May '18

08 May '18

commit a17dc0875ad0d434d9cf66d36ed23fbd69286bf3 Author: Nick Mathewson <nickm(a)torproject.org> Date: Mon May 7 13:56:39 2018 -0400 Avoid unsigned integer underflow on empty input. --- src/or/dirserv.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/src/or/dirserv.c b/src/or/dirserv.c index d9a9b8522..e47533759 100644 --- a/src/or/dirserv.c +++ b/src/or/dirserv.c @@ -2641,6 +2641,12 @@ measured_bw_line_parse(measured_bw_line_t *out, const char *orig_line) int got_node_id = 0; char *strtok_state; /* lame sauce d'jour */ + if (strlen(line) == 0) { + log_warn(LD_DIRSERV, "Empty line in bandwidth file"); + tor_free(line); + return -1; + } + /* Remove end of line character, so that is not part of the token */ if (line[strlen(line) - 1] == '\n') { line[strlen(line) - 1] = '\0';

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[tor/master] Merge branch 'bug26004_029_squashed'
by nickm＠torproject.org 08 May '18

08 May '18

commit 3df37d7b6be4f7d6ece0cd12812595d5f91ea72f Merge: 5edc72a45 bed3e8da9 Author: Nick Mathewson <nickm(a)torproject.org> Date: Tue May 8 14:26:05 2018 -0400 Merge branch 'bug26004_029_squashed' changes/ticket26004 | 5 +++++ src/or/dirserv.c | 12 ++++++++++++ src/test/test_dir.c | 7 +++++++ 3 files changed, 24 insertions(+)

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[tor/master] Add a changes file for ticket 26004.
by nickm＠torproject.org 08 May '18

08 May '18

commit bed3e8da9cc291546da06d5a5163a3598650d545 Author: Nick Mathewson <nickm(a)torproject.org> Date: Mon May 7 13:57:14 2018 -0400 Add a changes file for ticket 26004. --- changes/ticket26004 | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/changes/ticket26004 b/changes/ticket26004 new file mode 100644 index 000000000..6b082f145 --- /dev/null +++ b/changes/ticket26004 @@ -0,0 +1,5 @@ + o Minor features (directory authority, forward compatibility): + - Make the lines of the measured bandwidth file able to contain their + entries in any order. Previously, the node_id entry needed to come + first. Closes ticket 26004. +

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[tor/master] Allow bandwidth-file lines to have node_id in the last position
by nickm＠torproject.org 08 May '18

08 May '18

commit dbc80ad19b8a27aab557fe7930e18eef8f415133 Author: juga0 <juga(a)riseup.net> Date: Thu May 3 08:29:57 2018 +0000 Allow bandwidth-file lines to have node_id in the last position Closes ticket 26004. --- src/or/dirserv.c | 6 ++++++ src/test/test_dir.c | 7 +++++++ 2 files changed, 13 insertions(+) diff --git a/src/or/dirserv.c b/src/or/dirserv.c index 41c6bf3dc..d9a9b8522 100644 --- a/src/or/dirserv.c +++ b/src/or/dirserv.c @@ -2640,6 +2640,12 @@ measured_bw_line_parse(measured_bw_line_t *out, const char *orig_line) int got_bw = 0; int got_node_id = 0; char *strtok_state; /* lame sauce d'jour */ + + /* Remove end of line character, so that is not part of the token */ + if (line[strlen(line) - 1] == '\n') { + line[strlen(line) - 1] = '\0'; + } + cp = tor_strtok_r(cp, " \t", &strtok_state); if (!cp) { diff --git a/src/test/test_dir.c b/src/test/test_dir.c index cdc56acb8..b3817a092 100644 --- a/src/test/test_dir.c +++ b/src/test/test_dir.c @@ -1314,6 +1314,13 @@ test_dir_measured_bw_kb(void *arg) "bw=1024 junk=007\n", "misc=junk node_id=$557365204145532d32353620696e73746561642e " "bw=1024 junk=007\n", + /* check whether node_id can be at the end */ + "bw=1024 node_id=$557365204145532d32353620696e73746561642e\n", + /* check whether node_id can be at the end and bw has something in front*/ + "foo=bar bw=1024 node_id=$557365204145532d32353620696e73746561642e\n", + /* check whether node_id can be at the end and something in the + * in the middle of bw and node_id */ + "bw=1024 foo=bar node_id=$557365204145532d32353620696e73746561642e\n", "end" }; const char *lines_fail[] = {

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[torspec/master] Mention how HSLayer2Nodes and HSLayer3Nodes alter path restrictions.
by nickm＠torproject.org 08 May '18

08 May '18

commit 2058ddded039f532c61a94cdfcb190f2e8f74b1d Author: Mike Perry <mikeperry-git(a)torproject.org> Date: Tue May 8 16:39:10 2018 +0000 Mention how HSLayer2Nodes and HSLayer3Nodes alter path restrictions. --- path-spec.txt | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/path-spec.txt b/path-spec.txt index 0122dc5..15d9a3b 100644 --- a/path-spec.txt +++ b/path-spec.txt @@ -339,6 +339,11 @@ of their choices. <target>, and the request is only supported by the exit whose nickname or fingerprint is <servername>. + - When set, "HSLayer2Nodes" and "HSLayer3Nodes" relax Tor's path + restrictions to allow nodes in the same /16 and node family to reappear + in the path. They also allow the guard node to be chosen as the RP, IP, + and HSDIR, and as the hop before those positions. + 2.3. Cannibalizing circuits If we need a circuit and have a clean one already established, in

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[tor/master] Merge remote-tracking branch 'mikeperry/bug25870_rebase'
by nickm＠torproject.org 08 May '18

08 May '18

commit 5edc72a45b7479f5fe791054aa19f6b3b478c725 Merge: 2a4439adf e716c9212 Author: Nick Mathewson <nickm(a)torproject.org> Date: Tue May 8 14:12:29 2018 -0400 Merge remote-tracking branch 'mikeperry/bug25870_rebase' changes/bug25870 | 6 ++ doc/tor.1.txt | 16 ++++ src/or/circuitbuild.c | 109 +++++++++++++++++------- src/or/circuitbuild.h | 7 ++ src/or/entrynodes.c | 11 ++- src/or/entrynodes.h | 1 + src/test/test_entrynodes.c | 201 ++++++++++++++++++++++++++++++++++++++++++--- 7 files changed, 307 insertions(+), 44 deletions(-) diff --cc src/test/test_entrynodes.c index 6af18f8f4,c97aced04..cfcb88a66 --- a/src/test/test_entrynodes.c +++ b/src/test/test_entrynodes.c @@@ -14,9 -15,9 +15,10 @@@ #include "bridges.h" #include "circuitlist.h" + #include "circuitbuild.h" #include "config.h" #include "confparse.h" +#include "crypto_rand.h" #include "directory.h" #include "entrynodes.h" #include "nodelist.h"

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[tor/master] Fix memleak found by unittests.
by nickm＠torproject.org 08 May '18

08 May '18

commit e17f436fff541e0c31827f0e99bd345096d276e0 Author: George Kadianakis <desnacked(a)riseup.net> Date: Fri Apr 27 15:27:44 2018 +0300 Fix memleak found by unittests. --- src/or/circuitbuild.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c index 74e607d18..1eb3947ae 100644 --- a/src/or/circuitbuild.c +++ b/src/or/circuitbuild.c @@ -2633,7 +2633,9 @@ choose_good_middle_server(uint8_t purpose, /** If a hidden service circuit wants a specific middle node, pin it. */ if (middle_node_must_be_vanguard(options, purpose, cur_len)) { log_debug(LD_GENERAL, "Picking a sticky node (cur_len = %d)", cur_len); - return pick_vanguard_middle_node(options, flags, cur_len, excluded); + choice = pick_vanguard_middle_node(options, flags, cur_len, excluded); + smartlist_free(excluded); + return choice; } choice = router_choose_random_node(excluded, options->ExcludeNodes, flags);

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[tor/master] Bug 25870: Mention path restriction differences in manpage.
by nickm＠torproject.org 08 May '18

08 May '18

commit e716c92127f0da2fc5758c091a9e33857cd5e5d5 Author: Mike Perry <mikeperry-git(a)torproject.org> Date: Tue May 8 16:35:20 2018 +0000 Bug 25870: Mention path restriction differences in manpage. --- doc/tor.1.txt | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/doc/tor.1.txt b/doc/tor.1.txt index 05a612d6a..2f74d567e 100644 --- a/doc/tor.1.txt +++ b/doc/tor.1.txt @@ -1574,6 +1574,14 @@ The following options are useful only for clients (that is, if which means that nodes specified in ExcludeNodes will not be picked. + + When either this option or HSLayer3Nodes are set, the /16 subnet + and node family restrictions are removed for hidden service + circuits. Additionally, we allow the guard node to be present + as the Rend, HSDir, and IP node, and as the hop before it. This + is done to prevent the adversary from inferring information + about our guard, layer2, and layer3 node choices at later points + in the path. + + This option is meant to be managed by a Tor controller such as https://github.com/mikeperry-tor/vanguards that selects and updates this set of nodes for you. Hence it does not do load @@ -1619,6 +1627,14 @@ The following options are useful only for clients (that is, if ExcludeNodes have higher priority than HSLayer3Nodes, which means that nodes specified in ExcludeNodes will not be picked. + + + When either this option or HSLayer2Nodes are set, the /16 subnet + and node family restrictions are removed for hidden service + circuits. Additionally, we allow the guard node to be present + as the Rend, HSDir, and IP node, and as the hop before it. This + is done to prevent the adversary from inferring information + about our guard, layer2, and layer3 node choices at later points + in the path. + This option is meant to be managed by a Tor controller such as https://github.com/mikeperry-tor/vanguards that selects and

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[tor/master] Write unittests to check basic vanguard path selection.
by nickm＠torproject.org 08 May '18

08 May '18

commit 627d2fdbf0903498807fdd21c59a91502d731f7d Author: George Kadianakis <desnacked(a)riseup.net> Date: Fri Apr 27 15:27:17 2018 +0300 Write unittests to check basic vanguard path selection. Adds two unittests: - First checks the path selection of basic Tor circs. - Second checks the path selection of vanguard circs. There is a TODO on the second unittest that we might want to test sooner than later, but it's not trivial to do it right now. To do these unittests we needed the following mods: - Make some functions STATIC. - Add some more fields to the big fake network nodes of test_entrynodes.c - Switch fake node nicknames to base32 (because base64 does not produce valid nicknames). --- src/or/circuitbuild.c | 7 +- src/or/circuitbuild.h | 7 ++ src/test/test_entrynodes.c | 201 ++++++++++++++++++++++++++++++++++++++++++--- 3 files changed, 199 insertions(+), 16 deletions(-) diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c index 68ff964f6..74e607d18 100644 --- a/src/or/circuitbuild.c +++ b/src/or/circuitbuild.c @@ -72,10 +72,7 @@ static channel_t * channel_connect_for_circuit(const tor_addr_t *addr, static int circuit_deliver_create_cell(circuit_t *circ, const create_cell_t *create_cell, int relayed); -static int onion_pick_cpath_exit(origin_circuit_t *circ, extend_info_t *exit, - int is_hs_v3_rp_circuit); static crypt_path_t *onion_next_hop_in_cpath(crypt_path_t *cpath); -static int onion_extend_cpath(origin_circuit_t *circ); STATIC int onion_append_hop(crypt_path_t **head_ptr, extend_info_t *choice); static int circuit_send_first_onion_skin(origin_circuit_t *circ); static int circuit_build_no_more_hops(origin_circuit_t *circ); @@ -2285,7 +2282,7 @@ warn_if_last_router_excluded(origin_circuit_t *circ, * be used as an HS v3 rendezvous point. * * Return 0 if ok, -1 if circuit should be closed. */ -static int +STATIC int onion_pick_cpath_exit(origin_circuit_t *circ, extend_info_t *exit_ei, int is_hs_v3_rp_circuit) { @@ -2719,7 +2716,7 @@ onion_next_hop_in_cpath(crypt_path_t *cpath) * Return 1 if the path is complete, 0 if we successfully added a hop, * and -1 on error. */ -static int +STATIC int onion_extend_cpath(origin_circuit_t *circ) { uint8_t purpose = circ->base_.purpose; diff --git a/src/or/circuitbuild.h b/src/or/circuitbuild.h index bea31ad0d..ae4aef768 100644 --- a/src/or/circuitbuild.h +++ b/src/or/circuitbuild.h @@ -83,6 +83,13 @@ STATIC circid_t get_unique_circ_id_by_chan(channel_t *chan); STATIC int new_route_len(uint8_t purpose, extend_info_t *exit_ei, smartlist_t *nodes); MOCK_DECL(STATIC int, count_acceptable_nodes, (smartlist_t *nodes)); + +STATIC int onion_extend_cpath(origin_circuit_t *circ); + +STATIC int +onion_pick_cpath_exit(origin_circuit_t *circ, extend_info_t *exit_ei, + int is_hs_v3_rp_circuit); + #if defined(ENABLE_TOR2WEB_MODE) || defined(TOR_UNIT_TESTS) STATIC const node_t *pick_tor2web_rendezvous_node(router_crn_flags_t flags, const or_options_t *options); diff --git a/src/test/test_entrynodes.c b/src/test/test_entrynodes.c index 92a860360..c97aced04 100644 --- a/src/test/test_entrynodes.c +++ b/src/test/test_entrynodes.c @@ -4,6 +4,7 @@ #include "orconfig.h" #define CIRCUITLIST_PRIVATE +#define CIRCUITBUILD_PRIVATE #define STATEFILE_PRIVATE #define ENTRYNODES_PRIVATE #define ROUTERLIST_PRIVATE @@ -14,6 +15,7 @@ #include "bridges.h" #include "circuitlist.h" +#include "circuitbuild.h" #include "config.h" #include "confparse.h" #include "directory.h" @@ -74,6 +76,17 @@ bfn_mock_node_get_by_id(const char *id) return NULL; } +/* Helper function to free a test node. */ +static void +test_node_free(node_t *n) +{ + tor_free(n->rs); + tor_free(n->md->onion_curve25519_pkey); + short_policy_free(n->md->exit_policy); + tor_free(n->md); + tor_free(n); +} + /* Unittest cleanup function: Cleanup the fake network. */ static int big_fake_network_cleanup(const struct testcase_t *testcase, void *ptr) @@ -83,9 +96,7 @@ big_fake_network_cleanup(const struct testcase_t *testcase, void *ptr) if (big_fake_net_nodes) { SMARTLIST_FOREACH(big_fake_net_nodes, node_t *, n, { - tor_free(n->rs); - tor_free(n->md); - tor_free(n); + test_node_free(n); }); smartlist_free(big_fake_net_nodes); } @@ -113,9 +124,18 @@ big_fake_network_setup(const struct testcase_t *testcase) big_fake_net_nodes = smartlist_new(); for (i = 0; i < N_NODES; ++i) { + curve25519_secret_key_t curve25519_secret_key; + node_t *n = tor_malloc_zero(sizeof(node_t)); n->md = tor_malloc_zero(sizeof(microdesc_t)); + /* Generate curve25519 key for this node */ + n->md->onion_curve25519_pkey = + tor_malloc_zero(sizeof(curve25519_public_key_t)); + curve25519_secret_key_generate(&curve25519_secret_key, 0); + curve25519_public_key_generate(n->md->onion_curve25519_pkey, + &curve25519_secret_key); + crypto_rand(n->identity, sizeof(n->identity)); n->rs = tor_malloc_zero(sizeof(routerstatus_t)); @@ -135,8 +155,8 @@ big_fake_network_setup(const struct testcase_t *testcase) { char nickname_binary[8]; crypto_rand(nickname_binary, sizeof(nickname_binary)); - base64_encode(n->rs->nickname, sizeof(n->rs->nickname), - nickname_binary, sizeof(nickname_binary), 0); + base32_encode(n->rs->nickname, sizeof(n->rs->nickname), + nickname_binary, sizeof(nickname_binary)); } /* Call half of the nodes a possible guard. */ @@ -144,6 +164,12 @@ big_fake_network_setup(const struct testcase_t *testcase) n->is_possible_guard = 1; n->rs->guardfraction_percentage = 100; n->rs->has_guardfraction = 1; + n->rs->is_possible_guard = 1; + } + + /* Make some of these nodes a possible exit */ + if (i % 7 == 0) { + n->md->exit_policy = parse_short_policy("accept 443"); } smartlist_add(big_fake_net_nodes, n); @@ -1075,9 +1101,7 @@ test_entry_guard_expand_sample_small_net(void *arg) /* Fun corner case: not enough guards to make up our whole sample size. */ SMARTLIST_FOREACH(big_fake_net_nodes, node_t *, n, { if (n_sl_idx >= 15) { - tor_free(n->rs); - tor_free(n->md); - tor_free(n); + test_node_free(n); SMARTLIST_DEL_CURRENT(big_fake_net_nodes, n); } else { n->rs->addr = 0; // make the filter reject this. @@ -1171,9 +1195,7 @@ test_entry_guard_update_from_consensus_status(void *arg) entry_guard_t *g = smartlist_get(gs->sampled_entry_guards, 5); node_t *n = (node_t*) bfn_mock_node_get_by_id(g->identity); smartlist_remove(big_fake_net_nodes, n); - tor_free(n->rs); - tor_free(n->md); - tor_free(n); + test_node_free(n); } update_approx_time(start + 300); sampled_guards_update_from_consensus(gs); @@ -2787,6 +2809,161 @@ test_entry_guard_outdated_dirserver_exclusion(void *arg) } } +/** Test helper to extend the <b>oc</b> circuit path <b>n</b> times and then + * ensure that the circuit is now complete. */ +static void +helper_extend_circuit_path_n_times(origin_circuit_t *oc, int n) +{ + int retval; + int i; + + /* Extend path n times */ + for (i = 0 ; i < n ; i++) { + retval = onion_extend_cpath(oc); + tt_int_op(retval, OP_EQ, 0); + tt_int_op(circuit_get_cpath_len(oc), OP_EQ, i+1); + } + + /* Now do it one last time and see that circ is complete */ + retval = onion_extend_cpath(oc); + tt_int_op(retval, OP_EQ, 1); + + done: + ; +} + +/** Test for basic Tor path selection. Makes sure we build 3-hop circuits. */ +static void +test_entry_guard_basic_path_selection(void *arg) +{ + (void) arg; + + int retval; + + /* Enable entry guards */ + or_options_t *options = get_options_mutable(); + options->UseEntryGuards = 1; + + /* disables /16 check since all nodes have the same addr... */ + options->EnforceDistinctSubnets = 0; + + /* Create our circuit */ + circuit_t *circ = dummy_origin_circuit_new(30); + origin_circuit_t *oc = TO_ORIGIN_CIRCUIT(circ); + oc->build_state = tor_malloc_zero(sizeof(cpath_build_state_t)); + + /* First pick the exit and pin it on the build_state */ + retval = onion_pick_cpath_exit(oc, NULL, 0); + tt_int_op(retval, OP_EQ, 0); + + /* Extend path 3 times. First we pick guard, then middle, then exit. */ + helper_extend_circuit_path_n_times(oc, 3); + + done: + circuit_free_(circ); +} + +/** Test helper to build an L2 and L3 vanguard list. The vanguard lists + * produced should be completely disjoint. */ +static void +helper_setup_vanguard_list(or_options_t *options) +{ + int i = 0; + + /* Add some nodes to the vanguard L2 list */ + options->HSLayer2Nodes = routerset_new(); + for (i = 0; i < 10 ; i += 2) { + node_t *vanguard_node = smartlist_get(big_fake_net_nodes, i); + tt_assert(vanguard_node->is_possible_guard); + routerset_parse(options->HSLayer2Nodes, vanguard_node->rs->nickname, "l2"); + } + /* also add some nodes to vanguard L3 list + * (L2 list and L3 list should be disjoint for this test to work) */ + options->HSLayer3Nodes = routerset_new(); + for (i = 10; i < 20 ; i += 2) { + node_t *vanguard_node = smartlist_get(big_fake_net_nodes, i); + tt_assert(vanguard_node->is_possible_guard); + routerset_parse(options->HSLayer3Nodes, vanguard_node->rs->nickname, "l3"); + } + + done: + ; +} + +/** Test to ensure that vanguard path selection works properly. Ensures that + * default vanguard circuits are 4 hops, and that path selection works + * correctly given the vanguard settings. */ +static void +test_entry_guard_vanguard_path_selection(void *arg) +{ + (void) arg; + + int retval; + + /* Enable entry guards */ + or_options_t *options = get_options_mutable(); + options->UseEntryGuards = 1; + + /* XXX disables /16 check */ + options->EnforceDistinctSubnets = 0; + + /* Setup our vanguard list */ + helper_setup_vanguard_list(options); + + /* Create our circuit */ + circuit_t *circ = dummy_origin_circuit_new(30); + origin_circuit_t *oc = TO_ORIGIN_CIRCUIT(circ); + oc->build_state = tor_malloc_zero(sizeof(cpath_build_state_t)); + oc->build_state->is_internal = 1; + + /* Switch circuit purpose to vanguards */ + circ->purpose = CIRCUIT_PURPOSE_HS_VANGUARDS; + + /* First pick the exit and pin it on the build_state */ + tt_int_op(oc->build_state->desired_path_len, OP_EQ, 0); + retval = onion_pick_cpath_exit(oc, NULL, 0); + tt_int_op(retval, OP_EQ, 0); + + /* Ensure that vanguards make 4-hop circuits by default */ + tt_int_op(oc->build_state->desired_path_len, OP_EQ, 4); + + /* Extend path as many times as needed to have complete circ. */ + helper_extend_circuit_path_n_times(oc, oc->build_state->desired_path_len); + + /* Test that the cpath linked list is set correctly. */ + crypt_path_t *l1_node = oc->cpath; + crypt_path_t *l2_node = l1_node->next; + crypt_path_t *l3_node = l2_node->next; + crypt_path_t *l4_node = l3_node->next; + crypt_path_t *l1_node_again = l4_node->next; + tt_ptr_op(l1_node, OP_EQ, l1_node_again); + + /* Test that L2 is indeed HSLayer2Node */ + retval = routerset_contains_extendinfo(options->HSLayer2Nodes, + l2_node->extend_info); + tt_int_op(retval, OP_EQ, 4); + /* test that L3 node is _not_ contained in HSLayer2Node */ + retval = routerset_contains_extendinfo(options->HSLayer2Nodes, + l3_node->extend_info); + tt_int_op(retval, OP_LT, 4); + + /* Test that L3 is indeed HSLayer3Node */ + retval = routerset_contains_extendinfo(options->HSLayer3Nodes, + l3_node->extend_info); + tt_int_op(retval, OP_EQ, 4); + /* test that L2 node is _not_ contained in HSLayer3Node */ + retval = routerset_contains_extendinfo(options->HSLayer3Nodes, + l2_node->extend_info); + tt_int_op(retval, OP_LT, 4); + + /* TODO: Test that L1 can be the same as exit. To test this we need start + enforcing EnforceDistinctSubnets again, which means that we need to give + each test node a different address which currently breaks some tests. */ + + done: + circuit_free_(circ); +} + static const struct testcase_setup_t big_fake_network = { big_fake_network_setup, big_fake_network_cleanup }; @@ -2848,6 +3025,8 @@ struct testcase_t entrynodes_tests[] = { BFN_TEST(select_and_cancel), BFN_TEST(drop_guards), BFN_TEST(outdated_dirserver_exclusion), + BFN_TEST(basic_path_selection), + BFN_TEST(vanguard_path_selection), UPGRADE_TEST(upgrade_a_circuit, "c1-done c2-done"), UPGRADE_TEST(upgrade_blocked_by_live_primary_guards, "c1-done c2-done"),

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[tor/master] Bug 25870: Prevent the creation of A - B - A vanguard sub-paths.
by nickm＠torproject.org 08 May '18

08 May '18

commit e34bf50604903fa54458a2e57271604440c5ad3e Author: Mike Perry <mikeperry-git(a)torproject.org> Date: Tue May 1 00:59:10 2018 +0000 Bug 25870: Prevent the creation of A - B - A vanguard sub-paths. These paths are illegal in Tor and relays will reject them. We do this by using specific nodes in the exclude list (but ignore /16 and family). --- src/or/circuitbuild.c | 81 ++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 57 insertions(+), 24 deletions(-) diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c index 75540e5d3..4bdc8a3ee 100644 --- a/src/or/circuitbuild.c +++ b/src/or/circuitbuild.c @@ -2445,12 +2445,56 @@ cpath_get_n_hops(crypt_path_t **head_ptr) #endif /* defined(TOR_UNIT_TESTS) */ /** + * Build the exclude list for vanguard circuits. + * + * For vanguard circuits we exclude all the already chosen nodes (including + * the exit) from being middle hops. + * + * For vanguard circuits, we don't apply any subnet or family restrictions. + * This is to avoid impossible-to-build circuit paths, or just situations where + * our earlier guards prevent us from using most of our later ones. + * + * The alternative is building the circuit in reverse. Reverse calls to + * onion_extend_cpath() (ie: select outer hops first) would then have the + * property that you don't gain information about inner hops by observing + * outer ones. See https://trac.torproject.org/projects/tor/ticket/24487 + * for this. + * + * (Note further that we still exclude the exit to prevent A - B - A + * at the end of the path. */ +static smartlist_t * +build_vanguard_middle_exclude_list(uint8_t purpose, + cpath_build_state_t *state, + crypt_path_t *head, + int cur_len) +{ + smartlist_t *excluded; + const node_t *r; + crypt_path_t *cpath; + int i; + + (void) purpose; + + excluded = smartlist_new(); + + /* Add the exit to the exclude list (note that the exit/last hop is always + * chosen first in circuit_establish_circuit()). */ + if ((r = build_state_get_exit_node(state))) { + smartlist_add(excluded, (node_t*)r); + } + + for (i = 0, cpath = head; cpath && i < cur_len; ++i, cpath=cpath->next) { + if ((r = node_get_by_id(cpath->extend_info->identity_digest))) { + smartlist_add(excluded, (node_t*)r); + } + } + + return excluded; +} + +/** * Build a list of nodes to exclude from the choice of this middle * hop, based on already chosen nodes. - * - * XXX: At present, this function does not exclude any nodes from - * the vanguard circuits. See - * https://trac.torproject.org/projects/tor/ticket/24487 */ static smartlist_t * build_middle_exclude_list(uint8_t purpose, @@ -2463,32 +2507,21 @@ build_middle_exclude_list(uint8_t purpose, crypt_path_t *cpath; int i; + /** Vanguard circuits have their own path selection rules */ + if (circuit_should_use_vanguards(purpose)) { + return build_vanguard_middle_exclude_list(purpose, state, head, cur_len); + } + excluded = smartlist_new(); - /* Add the exit to the exclude list (note that the exit/last hop is always - * chosen first in circuit_establish_circuit()). */ + /* For non-vanguard circuits, add the exit and its family to the exclude list + * (note that the exit/last hop is always chosen first in + * circuit_establish_circuit()). */ if ((r = build_state_get_exit_node(state))) { nodelist_add_node_and_family(excluded, r); } - /* XXX: We don't apply any other previously selected node restrictions for - * vanguards, and allow nodes to be reused for those hop positions in the - * same circuit. This is because after many rotations, you get to learn - * inner guard nodes through the nodes that are not selected for outer - * hops. - * - * The alternative is building the circuit in reverse. Reverse calls to - * onion_extend_cpath() (ie: select outer hops first) would then have the - * property that you don't gain information about inner hops by observing - * outer ones. See https://trac.torproject.org/projects/tor/ticket/24487 - * for this. - * - * (Note further that we can and do still exclude the exit in the block - * above, because it is chosen first in circuit_establish_circuit()..) */ - if (circuit_should_use_vanguards(purpose)) { - return excluded; - } - + /* also exclude all other already chosen nodes and their family */ for (i = 0, cpath = head; cpath && i < cur_len; ++i, cpath=cpath->next) { if ((r = node_get_by_id(cpath->extend_info->identity_digest))) { nodelist_add_node_and_family(excluded, r);

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