December 2017 - tor-commits - lists.torproject.org

[tor/master] Merge branch 'maint-0.3.1' into maint-0.3.2
by nickm＠torproject.org 11 Dec '17

11 Dec '17

commit dc79d5299d1ffebab06d2e5ea9ef5f9459e0fc9a Merge: acc462c96 d2031f2c6 Author: Nick Mathewson <nickm(a)torproject.org> Date: Mon Dec 11 16:46:00 2017 -0500 Merge branch 'maint-0.3.1' into maint-0.3.2

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[tor/release-0.3.1] Introduce cache for outdated microdesc dirservers.
by nickm＠torproject.org 11 Dec '17

11 Dec '17

commit 7fc64f02a3057405f9e75d70848afd2e9b95da05 Author: George Kadianakis <desnacked(a)riseup.net> Date: Mon Nov 6 14:48:22 2017 +0200 Introduce cache for outdated microdesc dirservers. We gonna use this cache to avoid dirservers without outdated md info. --- src/or/directory.c | 36 +++++++++++------- src/or/directory.h | 7 +++- src/or/microdesc.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++++ src/or/microdesc.h | 6 ++- src/or/networkstatus.c | 3 ++ 5 files changed, 138 insertions(+), 15 deletions(-) diff --git a/src/or/directory.c b/src/or/directory.c index 9494cf02b..129309ae4 100644 --- a/src/or/directory.c +++ b/src/or/directory.c @@ -117,7 +117,8 @@ static void dir_routerdesc_download_failed(smartlist_t *failed, int was_extrainfo, int was_descriptor_digests); static void dir_microdesc_download_failed(smartlist_t *failed, - int status_code); + int status_code, + const char *dir_id); static int client_likes_consensus(const struct consensus_cache_entry_t *ent, const char *want_url); @@ -2178,8 +2179,6 @@ static int handle_response_fetch_detached_signatures(dir_connection_t *, const response_handler_args_t *); static int handle_response_fetch_desc(dir_connection_t *, const response_handler_args_t *); -static int handle_response_fetch_microdesc(dir_connection_t *, - const response_handler_args_t *); static int handle_response_upload_dir(dir_connection_t *, const response_handler_args_t *); static int handle_response_upload_vote(dir_connection_t *, @@ -2839,7 +2838,7 @@ handle_response_fetch_desc(dir_connection_t *conn, * Handler function: processes a response to a request for a group of * microdescriptors **/ -static int +STATIC int handle_response_fetch_microdesc(dir_connection_t *conn, const response_handler_args_t *args) { @@ -2856,6 +2855,7 @@ handle_response_fetch_microdesc(dir_connection_t *conn, conn->base_.port); tor_assert(conn->requested_resource && !strcmpstart(conn->requested_resource, "d/")); + tor_assert_nonfatal(!tor_mem_is_zero(conn->identity_digest, DIGEST_LEN)); which = smartlist_new(); dir_split_resource_into_fingerprints(conn->requested_resource+2, which, NULL, @@ -2866,7 +2866,7 @@ handle_response_fetch_microdesc(dir_connection_t *conn, "soon.", status_code, escaped(reason), conn->base_.address, (int)conn->base_.port, conn->requested_resource); - dir_microdesc_download_failed(which, status_code); + dir_microdesc_download_failed(which, status_code, conn->identity_digest); SMARTLIST_FOREACH(which, char *, cp, tor_free(cp)); smartlist_free(which); return 0; @@ -2878,7 +2878,7 @@ handle_response_fetch_microdesc(dir_connection_t *conn, now, which); if (smartlist_len(which)) { /* Mark remaining ones as failed. */ - dir_microdesc_download_failed(which, status_code); + dir_microdesc_download_failed(which, status_code, conn->identity_digest); } if (mds && smartlist_len(mds)) { control_event_bootstrap(BOOTSTRAP_STATUS_LOADING_DESCRIPTORS, @@ -5546,13 +5546,14 @@ dir_routerdesc_download_failed(smartlist_t *failed, int status_code, * every 10 or 60 seconds (FOO_DESCRIPTOR_RETRY_INTERVAL) in main.c. */ } -/** Called when a connection to download microdescriptors has failed in whole - * or in part. failed is a list of every microdesc digest we didn't - * get. status_code is the http status code we received. Reschedule the - * microdesc downloads as appropriate. */ +/** Called when a connection to download microdescriptors from relay with + * dir_id has failed in whole or in part. failed is a list + * of every microdesc digest we didn't get. status_code is the http + * status code we received. Reschedule the microdesc downloads as + * appropriate. */ static void dir_microdesc_download_failed(smartlist_t *failed, - int status_code) + int status_code, const char *dir_id) { networkstatus_t *consensus = networkstatus_get_latest_consensus_by_flavor(FLAV_MICRODESC); @@ -5563,17 +5564,26 @@ dir_microdesc_download_failed(smartlist_t *failed, if (! consensus) return; + + /* We failed to fetch a microdescriptor from 'dir_id', note it down + * so that we don't try the same relay next time... */ + microdesc_note_outdated_dirserver(dir_id); + SMARTLIST_FOREACH_BEGIN(failed, const char *, d) { rs = router_get_mutable_consensus_status_by_descriptor_digest(consensus,d); if (!rs) continue; dls = &rs->dl_status; if (dls->n_download_failures >= - get_options()->TestingMicrodescMaxDownloadTries) + get_options()->TestingMicrodescMaxDownloadTries) { continue; - { + } + + { /* Increment the failure count for this md fetch */ char buf[BASE64_DIGEST256_LEN+1]; digest256_to_base64(buf, d); + log_info(LD_DIR, "Failed to download md %s from %s", + buf, hex_str(dir_id, DIGEST_LEN)); download_status_increment_failure(dls, status_code, buf, server, now); } diff --git a/src/or/directory.h b/src/or/directory.h index 14d5ae9ef..571c30a0f 100644 --- a/src/or/directory.h +++ b/src/or/directory.h @@ -166,7 +166,12 @@ STATIC char *accept_encoding_header(void); STATIC int allowed_anonymous_connection_compression_method(compress_method_t); STATIC void warn_disallowed_anonymous_compression_method(compress_method_t); -#endif +struct response_handler_args_t; + +STATIC int handle_response_fetch_microdesc(dir_connection_t *conn, + const struct response_handler_args_t *args); + +#endif /* defined(DIRECTORY_PRIVATE) */ #ifdef TOR_UNIT_TESTS /* Used only by test_dir.c */ diff --git a/src/or/microdesc.c b/src/or/microdesc.c index a4e6b409c..32242d005 100644 --- a/src/or/microdesc.c +++ b/src/or/microdesc.c @@ -74,6 +74,102 @@ HT_GENERATE2(microdesc_map, microdesc_t, node, microdesc_hash_, microdesc_eq_, 0.6, tor_reallocarray_, tor_free_) +/************************* md fetch fail cache *****************************/ + +/* If we end up with too many outdated dirservers, something probably went + * wrong so clean up the list. */ +#define TOO_MANY_OUTDATED_DIRSERVERS 30 + +/** List of dirservers with outdated microdesc information. The smartlist is + * filled with the hex digests of outdated dirservers. */ +static smartlist_t *outdated_dirserver_list = NULL; + +/** Note that we failed to fetch a microdescriptor from the relay with + * relay_digest (of size DIGEST_LEN). */ +void +microdesc_note_outdated_dirserver(const char *relay_digest) +{ + char relay_hexdigest[HEX_DIGEST_LEN+1]; + + /* Don't register outdated dirservers if we don't have a live consensus, + * since we might be trying to fetch microdescriptors that are not even + * currently active. */ + if (!networkstatus_get_live_consensus(approx_time())) { + return; + } + + if (!outdated_dirserver_list) { + outdated_dirserver_list = smartlist_new(); + } + + tor_assert(outdated_dirserver_list); + + /* If the list grows too big, clean it up */ + if (BUG(smartlist_len(outdated_dirserver_list) > + TOO_MANY_OUTDATED_DIRSERVERS)) { + microdesc_reset_outdated_dirservers_list(); + } + + /* Turn the binary relay digest to a hex since smartlists have better support + * for strings than digests. */ + base16_encode(relay_hexdigest,sizeof(relay_hexdigest), + relay_digest, DIGEST_LEN); + + /* Make sure we don't add a dirauth as an outdated dirserver */ + if (router_get_trusteddirserver_by_digest(relay_digest)) { + log_info(LD_GENERAL, "Auth %s gave us outdated dirinfo.", relay_hexdigest); + return; + } + + /* Don't double-add outdated dirservers */ + if (smartlist_contains_string(outdated_dirserver_list, relay_hexdigest)) { + return; + } + + /* Add it to the list of outdated dirservers */ + smartlist_add_strdup(outdated_dirserver_list, relay_hexdigest); + + log_info(LD_GENERAL, "Noted %s as outdated md dirserver", relay_hexdigest); +} + +/** Return True if the relay with relay_digest (size DIGEST_LEN) is an + * outdated dirserver */ +int +microdesc_relay_is_outdated_dirserver(const char *relay_digest) +{ + char relay_hexdigest[HEX_DIGEST_LEN+1]; + + if (!outdated_dirserver_list) { + return 0; + } + + /* Convert identity digest to hex digest */ + base16_encode(relay_hexdigest, sizeof(relay_hexdigest), + relay_digest, DIGEST_LEN); + + /* Last time we tried to fetch microdescs, was this directory mirror missing + * any mds we asked for? */ + if (smartlist_contains_string(outdated_dirserver_list, relay_hexdigest)) { + return 1; + } + + return 0; +} + +/** Reset the list of outdated dirservers. */ +void +microdesc_reset_outdated_dirservers_list(void) +{ + if (!outdated_dirserver_list) { + return; + } + + SMARTLIST_FOREACH(outdated_dirserver_list, char *, cp, tor_free(cp)); + smartlist_clear(outdated_dirserver_list); +} + +/****************************************************************************/ + /** Write the body of md into f, with appropriate annotations. * On success, return the total number of bytes written, and set * *annotation_len_out to the number of bytes written as @@ -789,6 +885,11 @@ microdesc_free_all(void) tor_free(the_microdesc_cache->journal_fname); tor_free(the_microdesc_cache); } + + if (outdated_dirserver_list) { + SMARTLIST_FOREACH(outdated_dirserver_list, char *, cp, tor_free(cp)); + smartlist_free(outdated_dirserver_list); + } } /** If there is a microdescriptor in cache whose sha256 digest is diff --git a/src/or/microdesc.h b/src/or/microdesc.h index 943873066..1be12156a 100644 --- a/src/or/microdesc.h +++ b/src/or/microdesc.h @@ -50,5 +50,9 @@ int we_fetch_microdescriptors(const or_options_t *options); int we_fetch_router_descriptors(const or_options_t *options); int we_use_microdescriptors_for_circuits(const or_options_t *options); -#endif +void microdesc_note_outdated_dirserver(const char *relay_digest); +int microdesc_relay_is_outdated_dirserver(const char *relay_digest); +void microdesc_reset_outdated_dirservers_list(void); + +#endif /* !defined(TOR_MICRODESC_H) */ diff --git a/src/or/networkstatus.c b/src/or/networkstatus.c index 997280de5..36e62020e 100644 --- a/src/or/networkstatus.c +++ b/src/or/networkstatus.c @@ -2041,6 +2041,9 @@ networkstatus_set_current_consensus(const char *consensus, "CLOCK_SKEW MIN_SKEW=%ld SOURCE=CONSENSUS", delta); } + /* We got a new consesus. Reset our md fetch fail cache */ + microdesc_reset_outdated_dirservers_list(); + router_dir_info_changed(); result = 0;

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[tor/master] Merge branch 'maint-0.3.2'
by nickm＠torproject.org 11 Dec '17

11 Dec '17

commit 3b2f4d1391ca3b55c1911f97394ee1cf395ad51a Merge: d5400d50e dc79d5299 Author: Nick Mathewson <nickm(a)torproject.org> Date: Mon Dec 11 16:46:00 2017 -0500 Merge branch 'maint-0.3.2'

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[tor/maint-0.3.1] Check number of usable guards when applying md restrictions.
by nickm＠torproject.org 11 Dec '17

11 Dec '17

commit 69f93f806c4531e9498257578a10935e7859390f Author: George Kadianakis <desnacked(a)riseup.net> Date: Mon Nov 20 18:11:59 2017 +0200 Check number of usable guards when applying md restrictions. We used to check whether we have enough filtered guards (guard set when torrc is applied) but that's not good enough, since that might be bad in some cases where many guards are not reachable (might cause overblocking and hence reacahbility issues). We now check if we have enough reachable filtered guards before applying md restrictions which should prevent overblocking. --- src/or/entrynodes.c | 30 ++++++++++++++---------------- src/or/entrynodes.h | 2 +- 2 files changed, 15 insertions(+), 17 deletions(-) diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c index dc02557b5..d63d9291b 100644 --- a/src/or/entrynodes.c +++ b/src/or/entrynodes.c @@ -966,7 +966,7 @@ entry_guard_learned_bridge_identity(const tor_addr_port_t *addrport, * violate it. */ STATIC int -num_reachable_filtered_guards(guard_selection_t *gs, +num_reachable_filtered_guards(const guard_selection_t *gs, const entry_guard_restriction_t *rst) { int n_reachable_filtered_guards = 0; @@ -1472,30 +1472,28 @@ guard_create_exit_restriction(const uint8_t *exit_id) return rst; } -/** If we have fewer than this many possible guards, don't set - * MD-availability-based restrictions: we might blacklist all of - * them. */ +/** If we have fewer than this many possible usable guards, don't set + * MD-availability-based restrictions: we might blacklist all of them. */ #define MIN_GUARDS_FOR_MD_RESTRICTION 10 /** Return true if we should set md dirserver restrictions. We might not want - * to set those if our network is too restricted, since we don't want to - * blacklist all our nodes. */ + * to set those if our guard options are too restricted, since we don't want + * to blacklist all of them. */ static int should_set_md_dirserver_restriction(void) { const guard_selection_t *gs = get_guard_selection_info(); + int num_usable_guards = num_reachable_filtered_guards(gs, NULL); - /* Compute the number of filtered guards */ - int n_filtered_guards = 0; - SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { - if (guard->is_filtered_guard) { - ++n_filtered_guards; - } - } SMARTLIST_FOREACH_END(guard); + /* Don't set restriction if too few reachable filtered guards. */ + if (num_usable_guards < MIN_GUARDS_FOR_MD_RESTRICTION) { + log_info(LD_GUARD, "Not setting md restriction: only %d" + " usable guards.", num_usable_guards); + return 0; + } - /* Do we have enough filtered guards that we feel okay about blacklisting - * some for MD restriction? */ - return (n_filtered_guards >= MIN_GUARDS_FOR_MD_RESTRICTION); + /* We have enough usable guards: set MD restriction */ + return 1; } /** Allocate and return an outdated md guard restriction. Return NULL if no diff --git a/src/or/entrynodes.h b/src/or/entrynodes.h index 29de627de..39bff1438 100644 --- a/src/or/entrynodes.h +++ b/src/or/entrynodes.h @@ -521,7 +521,7 @@ STATIC void entry_guard_consider_retry(entry_guard_t *guard); STATIC void make_guard_confirmed(guard_selection_t *gs, entry_guard_t *guard); STATIC void entry_guards_update_confirmed(guard_selection_t *gs); STATIC void entry_guards_update_primary(guard_selection_t *gs); -STATIC int num_reachable_filtered_guards(guard_selection_t *gs, +STATIC int num_reachable_filtered_guards(const guard_selection_t *gs, const entry_guard_restriction_t *rst); STATIC void sampled_guards_update_from_consensus(guard_selection_t *gs); /**

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[tor/maint-0.3.1] Skip dirserver restrictions in small networks.
by nickm＠torproject.org 11 Dec '17

11 Dec '17

commit c400ffc2e88dab54b070a856717fb0ee6fe096cb Author: George Kadianakis <desnacked(a)riseup.net> Date: Mon Nov 13 22:26:22 2017 +0200 Skip dirserver restrictions in small networks. --- src/or/entrynodes.c | 42 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 34 insertions(+), 8 deletions(-) diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c index f2ca7aac2..1cc24d8d6 100644 --- a/src/or/entrynodes.c +++ b/src/or/entrynodes.c @@ -1472,12 +1472,45 @@ guard_create_exit_restriction(const uint8_t *exit_id) return rst; } -/** Allocate and return an outdated md guard restriction. */ +/** If we have less than these many configured bridges, don't set dirserver + * restrictions because we might blacklist all of them. */ +#define TOO_FEW_BRIDGES_FOR_RESTRICTION 10 + +/** Return true if we should set md dirserver restrictions. We might not want + * to set those if our network is too restricted, since we don't want to + * blacklist all our nodes. */ +static int +should_set_md_dirserver_restriction(void) +{ + const guard_selection_t *gs = get_guard_selection_info(); + + /* Don't set a restriction if we are on a restricted guard selection */ + if (gs->type == GS_TYPE_RESTRICTED) { + return 0; + } + + /* Don't set restriction if we are using bridges and have too few of those */ + if (gs->type == GS_TYPE_BRIDGE && gs->sampled_entry_guards) { + int num_sampled_guards = smartlist_len(gs->sampled_entry_guards); + if (num_sampled_guards < TOO_FEW_BRIDGES_FOR_RESTRICTION) { + return 0; + } + } + + return 1; +} + +/** Allocate and return an outdated md guard restriction. Return NULL if no + * such restriction is needed. */ STATIC entry_guard_restriction_t * guard_create_dirserver_md_restriction(void) { entry_guard_restriction_t *rst = NULL; + if (!should_set_md_dirserver_restriction()) { + return NULL; + } + rst = tor_malloc_zero(sizeof(entry_guard_restriction_t)); rst->type = RST_OUTDATED_MD_DIRSERVER; @@ -1504,13 +1537,6 @@ guard_obeys_exit_restriction(const entry_guard_t *guard, static int guard_obeys_md_dirserver_restriction(const entry_guard_t *guard) { - /* Don't enforce dirserver restrictions for bridges since we might not have - * many of those. Be willing to try them over and over again for now. */ - /* XXX: Improvement might be possible here */ - if (guard->bridge_addr) { - return 1; - } - /* If this guard is an outdated dirserver, don't use it. */ if (microdesc_relay_is_outdated_dirserver(guard->identity)) { log_info(LD_GENERAL, "Skipping %s dirserver: outdated",

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[tor/maint-0.3.1] Merge remote-tracking branch 'public/bug23817_031' into maint-0.3.1
by nickm＠torproject.org 11 Dec '17

11 Dec '17

commit d2031f2c602c40c3cc5f96a0fba27435203e83e2 Merge: ae608408e 69f93f806 Author: Nick Mathewson <nickm(a)torproject.org> Date: Mon Dec 11 16:45:54 2017 -0500 Merge remote-tracking branch 'public/bug23817_031' into maint-0.3.1 changes/bug23817 | 3 ++ src/or/directory.c | 40 ++++++++++------ src/or/directory.h | 7 ++- src/or/entrynodes.c | 121 ++++++++++++++++++++++++++++++++++++++++++++----- src/or/entrynodes.h | 39 +++++++++++----- src/or/microdesc.c | 101 +++++++++++++++++++++++++++++++++++++++++ src/or/microdesc.h | 6 ++- src/or/networkstatus.c | 3 ++ 8 files changed, 280 insertions(+), 40 deletions(-)

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[tor/master] Merge remote-tracking branch 'public/bug23817_031' into maint-0.3.1
by nickm＠torproject.org 11 Dec '17

11 Dec '17

commit d2031f2c602c40c3cc5f96a0fba27435203e83e2 Merge: ae608408e 69f93f806 Author: Nick Mathewson <nickm(a)torproject.org> Date: Mon Dec 11 16:45:54 2017 -0500 Merge remote-tracking branch 'public/bug23817_031' into maint-0.3.1 changes/bug23817 | 3 ++ src/or/directory.c | 40 ++++++++++------ src/or/directory.h | 7 ++- src/or/entrynodes.c | 121 ++++++++++++++++++++++++++++++++++++++++++++----- src/or/entrynodes.h | 39 +++++++++++----- src/or/microdesc.c | 101 +++++++++++++++++++++++++++++++++++++++++ src/or/microdesc.h | 6 ++- src/or/networkstatus.c | 3 ++ 8 files changed, 280 insertions(+), 40 deletions(-)

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[tor/release-0.3.1] Introduce new guard restriction and use it to skip outdated dirs.
by nickm＠torproject.org 11 Dec '17

11 Dec '17

commit f61e3090fb2975ad8c2a5e138b87c62428c5f46b Author: George Kadianakis <desnacked(a)riseup.net> Date: Mon Nov 6 19:38:47 2017 +0200 Introduce new guard restriction and use it to skip outdated dirs. --- changes/bug23817 | 3 ++ src/or/directory.c | 4 +-- src/or/entrynodes.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++------- src/or/entrynodes.h | 37 +++++++++++++++------ 4 files changed, 116 insertions(+), 23 deletions(-) diff --git a/changes/bug23817 b/changes/bug23817 new file mode 100644 index 000000000..474094279 --- /dev/null +++ b/changes/bug23817 @@ -0,0 +1,3 @@ + o Minor bugfixes (descriptors): + - Don't try fetching microdescriptors from relays that have failed to + deliver them in the past. Fixes bug 23817; bugfix on 0.3.0.1-alpha. diff --git a/src/or/directory.c b/src/or/directory.c index 129309ae4..aec8ef5bf 100644 --- a/src/or/directory.c +++ b/src/or/directory.c @@ -464,7 +464,7 @@ directory_pick_generic_dirserver(dirinfo_type_t type, int pds_flags, log_warn(LD_BUG, "Called when we have UseBridges set."); if (should_use_directory_guards(options)) { - const node_t *node = guards_choose_dirguard(guard_state_out); + const node_t *node = guards_choose_dirguard(dir_purpose, guard_state_out); if (node) rs = node->rs; } else { @@ -598,7 +598,7 @@ directory_get_from_dirserver,( * sort of dir fetch we'll be doing, so it won't return a bridge * that can't answer our question. */ - const node_t *node = guards_choose_dirguard(&guard_state); + const node_t *node = guards_choose_dirguard(dir_purpose, &guard_state); if (node && node->ri) { /* every bridge has a routerinfo. */ routerinfo_t *ri = node->ri; diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c index 26f53cbfe..f2ca7aac2 100644 --- a/src/or/entrynodes.c +++ b/src/or/entrynodes.c @@ -1460,6 +1460,70 @@ guard_in_node_family(const entry_guard_t *guard, const node_t *node) } } +/* Allocate and return a new exit guard restriction (where exit_id is of + * size DIGEST_LEN) */ +STATIC entry_guard_restriction_t * +guard_create_exit_restriction(const uint8_t *exit_id) +{ + entry_guard_restriction_t *rst = NULL; + rst = tor_malloc_zero(sizeof(entry_guard_restriction_t)); + rst->type = RST_EXIT_NODE; + memcpy(rst->exclude_id, exit_id, DIGEST_LEN); + return rst; +} + +/** Allocate and return an outdated md guard restriction. */ +STATIC entry_guard_restriction_t * +guard_create_dirserver_md_restriction(void) +{ + entry_guard_restriction_t *rst = NULL; + + rst = tor_malloc_zero(sizeof(entry_guard_restriction_t)); + rst->type = RST_OUTDATED_MD_DIRSERVER; + + return rst; +} + +/* Return True if guard obeys the exit restriction rst. */ +static int +guard_obeys_exit_restriction(const entry_guard_t *guard, + const entry_guard_restriction_t *rst) +{ + tor_assert(rst->type == RST_EXIT_NODE); + + // Exclude the exit ID and all of its family. + const node_t *node = node_get_by_id((const char*)rst->exclude_id); + if (node && guard_in_node_family(guard, node)) + return 0; + + return tor_memneq(guard->identity, rst->exclude_id, DIGEST_LEN); +} + +/** Return True if guard should be used as a dirserver for fetching + * microdescriptors. */ +static int +guard_obeys_md_dirserver_restriction(const entry_guard_t *guard) +{ + /* Don't enforce dirserver restrictions for bridges since we might not have + * many of those. Be willing to try them over and over again for now. */ + /* XXX: Improvement might be possible here */ + if (guard->bridge_addr) { + return 1; + } + + /* If this guard is an outdated dirserver, don't use it. */ + if (microdesc_relay_is_outdated_dirserver(guard->identity)) { + log_info(LD_GENERAL, "Skipping %s dirserver: outdated", + hex_str(guard->identity, DIGEST_LEN)); + return 0; + } + + log_debug(LD_GENERAL, "%s dirserver obeys md restrictions", + hex_str(guard->identity, DIGEST_LEN)); + + return 1; +} + /** * Return true iff guard obeys the restrictions defined in rst. * (If rst is NULL, there are no restrictions.) @@ -1472,13 +1536,14 @@ entry_guard_obeys_restriction(const entry_guard_t *guard, if (! rst) return 1; // No restriction? No problem. - // Only one kind of restriction exists right now: excluding an exit - // ID and all of its family. - const node_t *node = node_get_by_id((const char*)rst->exclude_id); - if (node && guard_in_node_family(guard, node)) - return 0; + if (rst->type == RST_EXIT_NODE) { + return guard_obeys_exit_restriction(guard, rst); + } else if (rst->type == RST_OUTDATED_MD_DIRSERVER) { + return guard_obeys_md_dirserver_restriction(guard); + } - return tor_memneq(guard->identity, rst->exclude_id, DIGEST_LEN); + tor_assert_nonfatal_unreached(); + return 0; } /** @@ -2105,7 +2170,7 @@ entry_guard_has_higher_priority(entry_guard_t *a, entry_guard_t *b) } /** Release all storage held in restriction */ -static void +STATIC void entry_guard_restriction_free(entry_guard_restriction_t *rst) { tor_free(rst); @@ -3358,8 +3423,8 @@ guards_choose_guard(cpath_build_state_t *state, /* We're building to a targeted exit node, so that node can't be * chosen as our guard for this circuit. Remember that fact in a * restriction. */ - rst = tor_malloc_zero(sizeof(entry_guard_restriction_t)); - memcpy(rst->exclude_id, exit_id, DIGEST_LEN); + rst = guard_create_exit_restriction(exit_id); + tor_assert(rst); } if (entry_guard_pick_for_circuit(get_guard_selection_info(), GUARD_USAGE_TRAFFIC, @@ -3411,12 +3476,20 @@ remove_all_entry_guards(void) /** Helper: pick a directory guard, with whatever algorithm is used. */ const node_t * -guards_choose_dirguard(circuit_guard_state_t **guard_state_out) +guards_choose_dirguard(uint8_t dir_purpose, + circuit_guard_state_t **guard_state_out) { const node_t *r = NULL; + entry_guard_restriction_t *rst = NULL; + + /* If we are fetching microdescs, don't query outdated dirservers. */ + if (dir_purpose == DIR_PURPOSE_FETCH_MICRODESC) { + rst = guard_create_dirserver_md_restriction(); + } + if (entry_guard_pick_for_circuit(get_guard_selection_info(), GUARD_USAGE_DIRGUARD, - NULL, + rst, &r, guard_state_out) < 0) { tor_assert(r == NULL); diff --git a/src/or/entrynodes.h b/src/or/entrynodes.h index 735c7738b..29de627de 100644 --- a/src/or/entrynodes.h +++ b/src/or/entrynodes.h @@ -272,22 +272,28 @@ struct guard_selection_s { struct entry_guard_handle_t; +/** Types of restrictions we impose when picking guard nodes */ +typedef enum guard_restriction_type_t { + /* Don't pick the same guard node as our exit node (or its family) */ + RST_EXIT_NODE = 0, + /* Don't pick dirguards that have previously shown to be outdated */ + RST_OUTDATED_MD_DIRSERVER = 1 +} guard_restriction_type_t; + /** * A restriction to remember which entry guards are off-limits for a given * circuit. * - * Right now, we only use restrictions to block a single guard and its family - * from being selected; this mechanism is designed to be more extensible in - * the future, however. - * * Note: This mechanism is NOT for recording which guards are never to be * used: only which guards cannot be used on one particular circuit. */ struct entry_guard_restriction_t { - /** - * The guard's RSA identity digest must not equal this; and it must not - * be in the same family as any node with this digest. - */ + /* What type of restriction are we imposing? */ + guard_restriction_type_t type; + + /* In case of restriction type RST_EXIT_NODE, the guard's RSA identity + * digest must not equal this; and it must not be in the same family as any + * node with this digest. */ uint8_t exclude_id[DIGEST_LEN]; }; @@ -316,7 +322,8 @@ struct circuit_guard_state_t { int guards_update_all(void); const node_t *guards_choose_guard(cpath_build_state_t *state, circuit_guard_state_t **guard_state_out); -const node_t *guards_choose_dirguard(circuit_guard_state_t **guard_state_out); +const node_t *guards_choose_dirguard(uint8_t dir_purpose, + circuit_guard_state_t **guard_state_out); #if 1 /* XXXX NM I would prefer that all of this stuff be private to @@ -550,7 +557,17 @@ STATIC unsigned entry_guards_note_guard_success(guard_selection_t *gs, unsigned old_state); STATIC int entry_guard_has_higher_priority(entry_guard_t *a, entry_guard_t *b); STATIC char *getinfo_helper_format_single_entry_guard(const entry_guard_t *e); -#endif + +STATIC entry_guard_restriction_t * +guard_create_exit_restriction(const uint8_t *exit_id); + +STATIC entry_guard_restriction_t * +guard_create_dirserver_md_restriction(void); + +STATIC void +entry_guard_restriction_free(entry_guard_restriction_t *rst); + +#endif /* defined(ENTRYNODES_PRIVATE) */ void remove_all_entry_guards_for_guard_selection(guard_selection_t *gs); void remove_all_entry_guards(void);

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[tor/release-0.3.1] Check number of usable guards when applying md restrictions.
by nickm＠torproject.org 11 Dec '17

11 Dec '17

commit 69f93f806c4531e9498257578a10935e7859390f Author: George Kadianakis <desnacked(a)riseup.net> Date: Mon Nov 20 18:11:59 2017 +0200 Check number of usable guards when applying md restrictions. We used to check whether we have enough filtered guards (guard set when torrc is applied) but that's not good enough, since that might be bad in some cases where many guards are not reachable (might cause overblocking and hence reacahbility issues). We now check if we have enough reachable filtered guards before applying md restrictions which should prevent overblocking. --- src/or/entrynodes.c | 30 ++++++++++++++---------------- src/or/entrynodes.h | 2 +- 2 files changed, 15 insertions(+), 17 deletions(-) diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c index dc02557b5..d63d9291b 100644 --- a/src/or/entrynodes.c +++ b/src/or/entrynodes.c @@ -966,7 +966,7 @@ entry_guard_learned_bridge_identity(const tor_addr_port_t *addrport, * violate it. */ STATIC int -num_reachable_filtered_guards(guard_selection_t *gs, +num_reachable_filtered_guards(const guard_selection_t *gs, const entry_guard_restriction_t *rst) { int n_reachable_filtered_guards = 0; @@ -1472,30 +1472,28 @@ guard_create_exit_restriction(const uint8_t *exit_id) return rst; } -/** If we have fewer than this many possible guards, don't set - * MD-availability-based restrictions: we might blacklist all of - * them. */ +/** If we have fewer than this many possible usable guards, don't set + * MD-availability-based restrictions: we might blacklist all of them. */ #define MIN_GUARDS_FOR_MD_RESTRICTION 10 /** Return true if we should set md dirserver restrictions. We might not want - * to set those if our network is too restricted, since we don't want to - * blacklist all our nodes. */ + * to set those if our guard options are too restricted, since we don't want + * to blacklist all of them. */ static int should_set_md_dirserver_restriction(void) { const guard_selection_t *gs = get_guard_selection_info(); + int num_usable_guards = num_reachable_filtered_guards(gs, NULL); - /* Compute the number of filtered guards */ - int n_filtered_guards = 0; - SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { - if (guard->is_filtered_guard) { - ++n_filtered_guards; - } - } SMARTLIST_FOREACH_END(guard); + /* Don't set restriction if too few reachable filtered guards. */ + if (num_usable_guards < MIN_GUARDS_FOR_MD_RESTRICTION) { + log_info(LD_GUARD, "Not setting md restriction: only %d" + " usable guards.", num_usable_guards); + return 0; + } - /* Do we have enough filtered guards that we feel okay about blacklisting - * some for MD restriction? */ - return (n_filtered_guards >= MIN_GUARDS_FOR_MD_RESTRICTION); + /* We have enough usable guards: set MD restriction */ + return 1; } /** Allocate and return an outdated md guard restriction. Return NULL if no diff --git a/src/or/entrynodes.h b/src/or/entrynodes.h index 29de627de..39bff1438 100644 --- a/src/or/entrynodes.h +++ b/src/or/entrynodes.h @@ -521,7 +521,7 @@ STATIC void entry_guard_consider_retry(entry_guard_t *guard); STATIC void make_guard_confirmed(guard_selection_t *gs, entry_guard_t *guard); STATIC void entry_guards_update_confirmed(guard_selection_t *gs); STATIC void entry_guards_update_primary(guard_selection_t *gs); -STATIC int num_reachable_filtered_guards(guard_selection_t *gs, +STATIC int num_reachable_filtered_guards(const guard_selection_t *gs, const entry_guard_restriction_t *rst); STATIC void sampled_guards_update_from_consensus(guard_selection_t *gs); /**

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[tor/release-0.3.1] Skip dirserver restrictions in small networks.
by nickm＠torproject.org 11 Dec '17

11 Dec '17

commit c400ffc2e88dab54b070a856717fb0ee6fe096cb Author: George Kadianakis <desnacked(a)riseup.net> Date: Mon Nov 13 22:26:22 2017 +0200 Skip dirserver restrictions in small networks. --- src/or/entrynodes.c | 42 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 34 insertions(+), 8 deletions(-) diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c index f2ca7aac2..1cc24d8d6 100644 --- a/src/or/entrynodes.c +++ b/src/or/entrynodes.c @@ -1472,12 +1472,45 @@ guard_create_exit_restriction(const uint8_t *exit_id) return rst; } -/** Allocate and return an outdated md guard restriction. */ +/** If we have less than these many configured bridges, don't set dirserver + * restrictions because we might blacklist all of them. */ +#define TOO_FEW_BRIDGES_FOR_RESTRICTION 10 + +/** Return true if we should set md dirserver restrictions. We might not want + * to set those if our network is too restricted, since we don't want to + * blacklist all our nodes. */ +static int +should_set_md_dirserver_restriction(void) +{ + const guard_selection_t *gs = get_guard_selection_info(); + + /* Don't set a restriction if we are on a restricted guard selection */ + if (gs->type == GS_TYPE_RESTRICTED) { + return 0; + } + + /* Don't set restriction if we are using bridges and have too few of those */ + if (gs->type == GS_TYPE_BRIDGE && gs->sampled_entry_guards) { + int num_sampled_guards = smartlist_len(gs->sampled_entry_guards); + if (num_sampled_guards < TOO_FEW_BRIDGES_FOR_RESTRICTION) { + return 0; + } + } + + return 1; +} + +/** Allocate and return an outdated md guard restriction. Return NULL if no + * such restriction is needed. */ STATIC entry_guard_restriction_t * guard_create_dirserver_md_restriction(void) { entry_guard_restriction_t *rst = NULL; + if (!should_set_md_dirserver_restriction()) { + return NULL; + } + rst = tor_malloc_zero(sizeof(entry_guard_restriction_t)); rst->type = RST_OUTDATED_MD_DIRSERVER; @@ -1504,13 +1537,6 @@ guard_obeys_exit_restriction(const entry_guard_t *guard, static int guard_obeys_md_dirserver_restriction(const entry_guard_t *guard) { - /* Don't enforce dirserver restrictions for bridges since we might not have - * many of those. Be willing to try them over and over again for now. */ - /* XXX: Improvement might be possible here */ - if (guard->bridge_addr) { - return 1; - } - /* If this guard is an outdated dirserver, don't use it. */ if (microdesc_relay_is_outdated_dirserver(guard->identity)) { log_info(LD_GENERAL, "Skipping %s dirserver: outdated",

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