Hello! I am sending this email a little early (before the website has had a chance to update) because today's releases are security relevant.
If you build Tor from source, the source code is available at https://dist.torproject.org/ . Packages should be available over the coming days.
Before I post the changelogs below, I'll give an overview of the security issues and the more important security fixes.
In brief: * Directory authorities should upgrade. * Relays running 0.3.2.1-alpha through 0.3.2.9 should upgrade. * Relays running 0.3.3.1-alpha should upgrade. * All other relays may wish to upgrade in order to improve their resistance to denial-of-service attacks.
TROVE-2018-001 only affects directory authorities. It is a bug that an attacker can use to cause a remote directory authority to crash. All directory authorities should upgrade to one of the versions released today. It does not affect relays or clients.
TROVE-2018-002 affects relays running all 0.3.2.x, versions, as well as 0.3.3.1-alpha. (Because we have found that it can be remotely triggered, we are backporting it and upgrading its severity.) It is a use-after-free bug in the KIST scheduler code, which an attacker can use to cause a relay to crash. Use-after-free bugs can sometimes be turned into worse attacks: we strongly recommend that all relays running 0.3.2.x (or 0.3.3.1-alpha) should upgrade to one of the versions released today. This issue does not affect other versions, and does not affect clients.
TROVE-2018-003 and TROVE-2018-004 are low-severity; see the changelogs for more information.
These releases also backport our denial-of-service mitigation code, tracked with ticket #24902. If you are running a relay, you might want to backport in order to get those fixes, especially if your relay is overloaded.
Here are the changes in today's releases:
Changes in version 0.3.3.3-alpha - 2018-03-03 Tor 0.3.3.3-alpha is the third alpha release for the 0.3.3.x series. It includes an important security fix for a remote crash attack against directory authorities tracked as TROVE-2018-001.
Additionally, with this release, we are upgrading the severity of a bug fixed in 0.3.3.2-alpha. Bug 24700, which was fixed in 0.3.3.2-alpha, can be remotely triggered in order to crash relays with a use-after-free pattern. As such, we are now tracking that bug as TROVE-2018-002 and CVE-2018-0491. This bug affected versions 0.3.2.1-alpha through 0.3.2.9, as well as 0.3.3.1-alpha.
This release also fixes several minor bugs and annoyances from earlier releases.
Relays running 0.3.2.x should upgrade to one of the versions released today, for the fix to TROVE-2018-002. Directory authorities should also upgrade. (Relays on earlier versions might want to update too for the DoS mitigations.)
o Major bugfixes (denial-of-service, directory authority): - Fix a protocol-list handling bug that could be used to remotely crash directory authorities with a null-pointer exception. Fixes bug 25074; bugfix on 0.2.9.4-alpha. Also tracked as TROVE-2018-001 and CVE-2018-0490.
o Minor features (compatibility, OpenSSL): - Tor will now support TLS1.3 once OpenSSL 1.1.1 is released. Previous versions of Tor would not have worked with OpenSSL 1.1.1, since they neither disabled TLS 1.3 nor enabled any of the ciphersuites it requires. Now we enable the TLS 1.3 ciphersuites. Closes ticket 24978.
o Minor features (logging): - Clarify the log messages produced when getrandom() or a related entropy-generation mechanism gives an error. Closes ticket 25120.
o Minor features (testing): - Add a "make test-rust" target to run the rust tests only. Closes ticket 25071.
o Minor bugfixes (denial-of-service): - Fix a possible crash on malformed consensus. If a consensus had contained an unparseable protocol line, it could have made clients and relays crash with a null-pointer exception. To exploit this issue, however, an attacker would need to be able to subvert the directory authority system. Fixes bug 25251; bugfix on 0.2.9.4-alpha. Also tracked as TROVE-2018-004.
o Minor bugfixes (DoS mitigation): - Add extra safety checks when refilling the circuit creation bucket to ensure we never set a value above the allowed maximum burst. Fixes bug 25202; bugfix on 0.3.3.2-alpha. - When a new consensus arrives, don't update our DoS-mitigation parameters if we aren't a public relay. Fixes bug 25223; bugfix on 0.3.3.2-alpha.
o Minor bugfixes (man page, SocksPort): - Remove dead code from the old "SocksSocket" option, and rename SocksSocketsGroupWritable to UnixSocksGroupWritable. The old option still works, but is deprecated. Fixes bug 24343; bugfix on 0.2.6.3.
o Minor bugfixes (performance): - Reduce the number of circuits that will be opened at once during the circuit build timeout phase. This is done by increasing the idle timeout to 3 minutes, and lowering the maximum number of concurrent learning circuits to 10. Fixes bug 24769; bugfix on 0.3.1.1-alpha.
o Minor bugfixes (spec conformance): - Forbid "-0" as a protocol version. Fixes part of bug 25249; bugfix on 0.2.9.4-alpha. - Forbid UINT32_MAX as a protocol version. Fixes part of bug 25249; bugfix on 0.2.9.4-alpha.
o Minor bugfixes (spec conformance, rust): - Resolve a denial-of-service issue caused by an infinite loop in the rust protover code. Fixes bug 25250, bugfix on 0.3.3.1-alpha. Also tracked as TROVE-2018-003.
o Code simplification and refactoring: - Update the "rust dependencies" submodule to be a project-level repository, rather than a user repository. Closes ticket 25323.
Changes in version 0.3.2.10 - 2018-03-03 Tor 0.3.2.10 is the second stable release in the 0.3.2 series. It backports a number of bugfixes, including important fixes for security issues.
It includes an important security fix for a remote crash attack against directory authorities, tracked as TROVE-2018-001.
Additionally, it backports a fix for a bug whose severity we have upgraded: Bug 24700, which was fixed in 0.3.3.2-alpha, can be remotely triggered in order to crash relays with a use-after-free pattern. As such, we are now tracking that bug as TROVE-2018-002 and CVE-2018-0491, and backporting it to earlier releases. This bug affected versions 0.3.2.1-alpha through 0.3.2.9, as well as version 0.3.3.1-alpha.
This release also backports our new system for improved resistance to denial-of-service attacks against relays.
This release also fixes several minor bugs and annoyances from earlier releases.
Relays running 0.3.2.x SHOULD upgrade to one of the versions released today, for the fix to TROVE-2018-002. Directory authorities should also upgrade. (Relays on earlier versions might want to update too for the DoS mitigations.)
o Major bugfixes (denial-of-service, directory authority, backport from 0.3.3.3-alpha): - Fix a protocol-list handling bug that could be used to remotely crash directory authorities with a null-pointer exception. Fixes bug 25074; bugfix on 0.2.9.4-alpha. Also tracked as TROVE-2018-001 and CVE-2018-0490.
o Major bugfixes (scheduler, KIST, denial-of-service, backport from 0.3.3.2-alpha): - Avoid adding the same channel twice in the KIST scheduler pending list, which could lead to remote denial-of-service use-after-free attacks against relays. Fixes bug 24700; bugfix on 0.3.2.1-alpha.
o Major features (denial-of-service mitigation, backport from 0.3.3.2-alpha): - Give relays some defenses against the recent network overload. We start with three defenses (default parameters in parentheses). First: if a single client address makes too many concurrent connections (>100), hang up on further connections. Second: if a single client address makes circuits too quickly (more than 3 per second, with an allowed burst of 90) while also having too many connections open (3), refuse new create cells for the next while (1-2 hours). Third: if a client asks to establish a rendezvous point to you directly, ignore the request. These defenses can be manually controlled by new torrc options, but relays will also take guidance from consensus parameters, so there's no need to configure anything manually. Implements ticket 24902.
o Major bugfixes (onion services, retry behavior, backport from 0.3.3.1-alpha): - Fix an "off by 2" error in counting rendezvous failures on the onion service side. While we thought we would stop the rendezvous attempt after one failed circuit, we were actually making three circuit attempts before giving up. Now switch to a default of 2, and allow the consensus parameter "hs_service_max_rdv_failures" to override. Fixes bug 24895; bugfix on 0.0.6. - New-style (v3) onion services now obey the "max rendezvous circuit attempts" logic. Previously they would make as many rendezvous circuit attempts as they could fit in the MAX_REND_TIMEOUT second window before giving up. Fixes bug 24894; bugfix on 0.3.2.1-alpha.
o Major bugfixes (protocol versions, backport from 0.3.3.2-alpha): - Add Link protocol version 5 to the supported protocols list. Fixes bug 25070; bugfix on 0.3.1.1-alpha.
o Major bugfixes (relay, backport from 0.3.3.1-alpha): - Fix a set of false positives where relays would consider connections to other relays as being client-only connections (and thus e.g. deserving different link padding schemes) if those relays fell out of the consensus briefly. Now we look only at the initial handshake and whether the connection authenticated as a relay. Fixes bug 24898; bugfix on 0.3.1.1-alpha.
o Major bugfixes (scheduler, consensus, backport from 0.3.3.2-alpha): - The scheduler subsystem was failing to promptly notice changes in consensus parameters, making it harder to switch schedulers network-wide. Fixes bug 24975; bugfix on 0.3.2.1-alpha.
o Minor features (denial-of-service avoidance, backport from 0.3.3.2-alpha): - Make our OOM handler aware of the geoip client history cache so it doesn't fill up the memory. This check is important for IPv6 and our DoS mitigation subsystem. Closes ticket 25122.
o Minor features (compatibility, OpenSSL, backport from 0.3.3.3-alpha): - Tor will now support TLS1.3 once OpenSSL 1.1.1 is released. Previous versions of Tor would not have worked with OpenSSL 1.1.1, since they neither disabled TLS 1.3 nor enabled any of the ciphersuites it requires. Now we enable the TLS 1.3 ciphersuites. Closes ticket 24978.
o Minor features (geoip): - Update geoip and geoip6 to the February 7 2018 Maxmind GeoLite2 Country database.
o Minor features (logging, diagnostic, backport from 0.3.3.2-alpha): - When logging a failure to check a hidden service's certificate, also log what the problem with the certificate was. Diagnostic for ticket 24972.
o Minor bugfix (channel connection, backport from 0.3.3.2-alpha): - Use the actual observed address of an incoming relay connection, not the canonical address of the relay from its descriptor, when making decisions about how to handle the incoming connection. Fixes bug 24952; bugfix on 0.2.4.11-alpha. Patch by "ffmancera".
o Minor bugfixes (denial-of-service, backport from 0.3.3.3-alpha): - Fix a possible crash on malformed consensus. If a consensus had contained an unparseable protocol line, it could have made clients and relays crash with a null-pointer exception. To exploit this issue, however, an attacker would need to be able to subvert the directory authority system. Fixes bug 25251; bugfix on 0.2.9.4-alpha. Also tracked as TROVE-2018-004.
o Minor bugfix (directory authority, backport from 0.3.3.2-alpha): - Directory authorities, when refusing a descriptor from a rejected relay, now explicitly tell the relay (in its logs) to set a valid ContactInfo address and contact the bad-relays@ mailing list. Fixes bug 25170; bugfix on 0.2.9.1.
o Minor bugfixes (build, rust, backport from 0.3.3.1-alpha): - When building with Rust on OSX, link against libresolv, to work around the issue at https://github.com/rust-lang/rust/issues/46797. Fixes bug 24652; bugfix on 0.3.1.1-alpha.
o Minor bugfixes (onion services, backport from 0.3.3.2-alpha): - Remove a BUG() statement when a client fetches an onion descriptor that has a lower revision counter than the one in its cache. This can happen in normal circumstances due to HSDir desync. Fixes bug 24976; bugfix on 0.3.2.1-alpha.
o Minor bugfixes (logging, backport from 0.3.3.2-alpha): - Don't treat inability to store a cached consensus object as a bug: it can happen normally when we are out of disk space. Fixes bug 24859; bugfix on 0.3.1.1-alpha.
o Minor bugfixes (performance, fragile-hardening, backport from 0.3.3.1-alpha): - Improve the performance of our consensus-diff application code when Tor is built with the --enable-fragile-hardening option set. Fixes bug 24826; bugfix on 0.3.1.1-alpha.
o Minor bugfixes (OSX, backport from 0.3.3.1-alpha): - Don't exit the Tor process if setrlimit() fails to change the file limit (which can happen sometimes on some versions of OSX). Fixes bug 21074; bugfix on 0.0.9pre5.
o Minor bugfixes (spec conformance, backport from 0.3.3.3-alpha): - Forbid "-0" as a protocol version. Fixes part of bug 25249; bugfix on 0.2.9.4-alpha. - Forbid UINT32_MAX as a protocol version. Fixes part of bug 25249; bugfix on 0.2.9.4-alpha.
o Minor bugfixes (testing, backport from 0.3.3.1-alpha): - Fix a memory leak in the scheduler/loop_kist unit test. Fixes bug 25005; bugfix on 0.3.2.7-rc.
o Minor bugfixes (v3 onion services, backport from 0.3.3.2-alpha): - Look at the "HSRend" protocol version, not the "HSDir" protocol version, when deciding whether a consensus entry can support the v3 onion service protocol as a rendezvous point. Fixes bug 25105; bugfix on 0.3.2.1-alpha.
o Code simplification and refactoring (backport from 0.3.3.3-alpha): - Update the "rust dependencies" submodule to be a project-level repository, rather than a user repository. Closes ticket 25323.
o Documentation (backport from 0.3.3.1-alpha) - Document that operators who run more than one relay or bridge are expected to set MyFamily and ContactInfo correctly. Closes ticket 24526.
Changes in version 0.3.1.10 - 2018-03-03 Tor 0.3.1.10 backports a number of bugfixes, including important fixes for security issues.
It includes an important security fix for a remote crash attack against directory authorities, tracked as TROVE-2018-001.
This release also backports our new system for improved resistance to denial-of-service attacks against relays.
This release also fixes several minor bugs and annoyances from earlier releases.
All directory authorities should upgrade to one of the versions released today. Relays running 0.3.1.x may wish to update to one of the versions released today, for the DoS mitigations.
Please note: according to our release calendar, Tor 0.3.1 will no longer be supported after 1 July 2018. If you will be running Tor after that date, you should make sure to plan to upgrade to the latest stable version, or downgrade to 0.2.9 (which will receive long-term support).
o Major bugfixes (denial-of-service, directory authority, backport from 0.3.3.3-alpha): - Fix a protocol-list handling bug that could be used to remotely crash directory authorities with a null-pointer exception. Fixes bug 25074; bugfix on 0.2.9.4-alpha. Also tracked as TROVE-2018-001 and CVE-2018-0490.
o Major features (denial-of-service mitigation, backport from 0.3.3.2-alpha): - Give relays some defenses against the recent network overload. We start with three defenses (default parameters in parentheses). First: if a single client address makes too many concurrent connections (>100), hang up on further connections. Second: if a single client address makes circuits too quickly (more than 3 per second, with an allowed burst of 90) while also having too many connections open (3), refuse new create cells for the next while (1-2 hours). Third: if a client asks to establish a rendezvous point to you directly, ignore the request. These defenses can be manually controlled by new torrc options, but relays will also take guidance from consensus parameters, so there's no need to configure anything manually. Implements ticket 24902.
o Minor features (linux seccomp2 sandbox, backport from 0.3.2.5-alpha): - Update the sandbox rules so that they should now work correctly with Glibc 2.26. Closes ticket 24315.
o Major bugfixes (onion services, retry behavior, backport from 0.3.3.1-alpha): - Fix an "off by 2" error in counting rendezvous failures on the onion service side. While we thought we would stop the rendezvous attempt after one failed circuit, we were actually making three circuit attempts before giving up. Now switch to a default of 2, and allow the consensus parameter "hs_service_max_rdv_failures" to override. Fixes bug 24895; bugfix on 0.0.6.
o Major bugfixes (protocol versions, backport from 0.3.3.2-alpha): - Add Link protocol version 5 to the supported protocols list. Fixes bug 25070; bugfix on 0.3.1.1-alpha.
o Major bugfixes (relay, backport from 0.3.3.1-alpha): - Fix a set of false positives where relays would consider connections to other relays as being client-only connections (and thus e.g. deserving different link padding schemes) if those relays fell out of the consensus briefly. Now we look only at the initial handshake and whether the connection authenticated as a relay. Fixes bug 24898; bugfix on 0.3.1.1-alpha.
o Minor features (denial-of-service avoidance, backport from 0.3.3.2-alpha): - Make our OOM handler aware of the geoip client history cache so it doesn't fill up the memory. This check is important for IPv6 and our DoS mitigation subsystem. Closes ticket 25122.
o Minor feature (relay statistics, backport from 0.3.2.6-alpha): - Change relay bandwidth reporting stats interval from 4 hours to 24 hours in order to reduce the efficiency of guard discovery attacks. Fixes ticket 23856.
o Minor features (compatibility, OpenSSL, backport from 0.3.3.3-alpha): - Tor will now support TLS1.3 once OpenSSL 1.1.1 is released. Previous versions of Tor would not have worked with OpenSSL 1.1.1, since they neither disabled TLS 1.3 nor enabled any of the ciphersuites it requires. Now we enable the TLS 1.3 ciphersuites. Closes ticket 24978.
o Minor features (fallback directory mirrors, backport from 0.3.2.9): - The fallback directory list has been re-generated based on the current status of the network. Tor uses fallback directories to bootstrap when it doesn't yet have up-to-date directory information. Closes ticket 24801. - Make the default DirAuthorityFallbackRate 0.1, so that clients prefer to bootstrap from fallback directory mirrors. This is a follow-up to 24679, which removed weights from the default fallbacks. Implements ticket 24681.
o Minor features (geoip): - Update geoip and geoip6 to the February 7 2018 Maxmind GeoLite2 Country database.
o Minor bugfix (channel connection, backport from 0.3.3.2-alpha): - Use the actual observed address of an incoming relay connection, not the canonical address of the relay from its descriptor, when making decisions about how to handle the incoming connection. Fixes bug 24952; bugfix on 0.2.4.11-alpha. Patch by "ffmancera".
o Minor bugfix (directory authority, backport from 0.3.3.2-alpha): - Directory authorities, when refusing a descriptor from a rejected relay, now explicitly tell the relay (in its logs) to set a valid ContactInfo address and contact the bad-relays@ mailing list. Fixes bug 25170; bugfix on 0.2.9.1.
o Minor bugfixes (address selection, backport from 0.3.2.9): - When the fascist_firewall_choose_address_ functions don't find a reachable address, set the returned address to the null address and port. This is a precautionary measure, because some callers do not check the return value. Fixes bug 24736; bugfix on 0.2.8.2-alpha.
o Major bugfixes (bootstrapping, backport from 0.3.2.5-alpha): - Fetch descriptors aggressively whenever we lack enough to build circuits, regardless of how many descriptors we are missing. Previously, we would delay launching the fetch when we had fewer than 15 missing descriptors, even if some of those descriptors were blocking circuits from building. Fixes bug 23985; bugfix on 0.1.1.11-alpha. The effects of this bug became worse in 0.3.0.3-alpha, when we began treating missing descriptors from our primary guards as a reason to delay circuits. - 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.
o Minor bugfixes (compilation, backport from 0.3.2.7-rc): - Fix a signed/unsigned comparison warning introduced by our fix to TROVE-2017-009. Fixes bug 24480; bugfix on 0.2.5.16.
o Minor bugfixes (control port, linux seccomp2 sandbox, backport from 0.3.2.5-alpha): - Avoid a crash when attempting to use the seccomp2 sandbox together with the OwningControllerProcess feature. Fixes bug 24198; bugfix on 0.2.5.1-alpha.
o Minor bugfixes (denial-of-service, backport from 0.3.3.3-alpha): - Fix a possible crash on malformed consensus. If a consensus had contained an unparseable protocol line, it could have made clients and relays crash with a null-pointer exception. To exploit this issue, however, an attacker would need to be able to subvert the directory authority system. Fixes bug 25251; bugfix on 0.2.9.4-alpha. Also tracked as TROVE-2018-004.
o Minor bugfixes (directory cache, backport from 0.3.2.5-alpha): - Recover better from empty or corrupt files in the consensus cache directory. Fixes bug 24099; bugfix on 0.3.1.1-alpha. - When a consensus diff calculation is only partially successful, only record the successful parts as having succeeded. Partial success can happen if (for example) one compression method fails but the others succeed. Previously we misrecorded all the calculations as having succeeded, which would later cause a nonfatal assertion failure. Fixes bug 24086; bugfix on 0.3.1.1-alpha.
o Minor bugfixes (entry guards, backport from 0.3.2.3-alpha): - Tor now updates its guard state when it reads a consensus regardless of whether it's missing descriptors. That makes tor use its primary guards to fetch descriptors in some edge cases where it would previously have used fallback directories. Fixes bug 23862; bugfix on 0.3.0.1-alpha.
o Minor bugfixes (logging, backport from 0.3.3.2-alpha): - Don't treat inability to store a cached consensus object as a bug: it can happen normally when we are out of disk space. Fixes bug 24859; bugfix on 0.3.1.1-alpha.
o Minor bugfixes (memory usage, backport from 0.3.2.8-rc): - When queuing DESTROY cells on a channel, only queue the circuit-id and reason fields: not the entire 514-byte cell. This fix should help mitigate any bugs or attacks that fill up these queues, and free more RAM for other uses. Fixes bug 24666; bugfix on 0.2.5.1-alpha.
o Minor bugfixes (network layer, backport from 0.3.2.5-alpha): - When closing a connection via close_connection_immediately(), we mark it as "not blocked on bandwidth", to prevent later calls from trying to unblock it, and give it permission to read. This fixes a backtrace warning that can happen on relays under various circumstances. Fixes bug 24167; bugfix on 0.1.0.1-rc.
o Minor bugfixes (path selection, backport from 0.3.2.4-alpha): - When selecting relays by bandwidth, avoid a rounding error that could sometimes cause load to be imbalanced incorrectly. Previously, we would always round upwards; now, we round towards the nearest integer. This had the biggest effect when a relay's weight adjustments should have given it weight 0, but it got weight 1 instead. Fixes bug 23318; bugfix on 0.2.4.3-alpha. - When calculating the fraction of nodes that have descriptors, and all nodes in the network have zero bandwidths, count the number of nodes instead. Fixes bug 23318; bugfix on 0.2.4.10-alpha. - Actually log the total bandwidth in compute_weighted_bandwidths(). Fixes bug 24170; bugfix on 0.2.4.3-alpha.
o Minor bugfixes (performance, fragile-hardening, backport from 0.3.3.1-alpha): - Improve the performance of our consensus-diff application code when Tor is built with the --enable-fragile-hardening option set. Fixes bug 24826; bugfix on 0.3.1.1-alpha.
o Minor bugfixes (OSX, backport from 0.3.3.1-alpha): - Don't exit the Tor process if setrlimit() fails to change the file limit (which can happen sometimes on some versions of OSX). Fixes bug 21074; bugfix on 0.0.9pre5.
o Minor bugfixes (portability, msvc, backport from 0.3.2.9): - Fix a bug in the bit-counting parts of our timing-wheel code on MSVC. (Note that MSVC is still not a supported build platform, due to cyptographic timing channel risks.) Fixes bug 24633; bugfix on 0.2.9.1-alpha.
o Minor bugfixes (relay, partial backport): - Make the internal channel_is_client() function look at what sort of connection handshake the other side used, rather than whether the other side ever sent a create_fast cell to us. Backports part of the fixes from bugs 22805 and 24898.
o Minor bugfixes (spec conformance, backport from 0.3.3.3-alpha): - Forbid "-0" as a protocol version. Fixes part of bug 25249; bugfix on 0.2.9.4-alpha. - Forbid UINT32_MAX as a protocol version. Fixes part of bug 25249; bugfix on 0.2.9.4-alpha.
o Code simplification and refactoring (backport from 0.3.3.3-alpha): - Update the "rust dependencies" submodule to be a project-level repository, rather than a user repository. Closes ticket 25323.
Changes in version 0.2.9.15 - 2018-03-03 Tor 0.2.9.15 backports important security and stability bugfixes from later Tor releases.
It includes an important security fix for a remote crash attack against directory authorities, tracked as TROVE-2018-001.
This release also backports our new system for improved resistance to denial-of-service attacks against relays.
This release also fixes several minor bugs and annoyances from earlier releases.
All directory authorities should upgrade to one of the versions released today. Relays running 0.2.9.x may wish to update to one of the versions released today, for the DoS mitigations.
o Major bugfixes (denial-of-service, directory authority, backport from 0.3.3.3-alpha): - Fix a protocol-list handling bug that could be used to remotely crash directory authorities with a null-pointer exception. Fixes bug 25074; bugfix on 0.2.9.4-alpha. Also tracked as TROVE-2018-001 and CVE-2018-0490.
o Major features (denial-of-service mitigation): - Give relays some defenses against the recent network overload. We start with three defenses (default parameters in parentheses). First: if a single client address makes too many concurrent connections (>100), hang up on further connections. Second: if a single client address makes circuits too quickly (more than 3 per second, with an allowed burst of 90) while also having too many connections open (3), refuse new create cells for the next while (1-2 hours). Third: if a client asks to establish a rendezvous point to you directly, ignore the request. These defenses can be manually controlled by new torrc options, but relays will also take guidance from consensus parameters, so there's no need to configure anything manually. Implements ticket 24902.
o Major bugfixes (bootstrapping): - Fetch descriptors aggressively whenever we lack enough to build circuits, regardless of how many descriptors we are missing. Previously, we would delay launching the fetch when we had fewer than 15 missing descriptors, even if some of those descriptors were blocking circuits from building. Fixes bug 23985; bugfix on 0.1.1.11-alpha. The effects of this bug became worse in 0.3.0.3-alpha, when we began treating missing descriptors from our primary guards as a reason to delay circuits.
o Major bugfixes (onion services, retry behavior): - Fix an "off by 2" error in counting rendezvous failures on the onion service side. While we thought we would stop the rendezvous attempt after one failed circuit, we were actually making three circuit attempts before giving up. Now switch to a default of 2, and allow the consensus parameter "hs_service_max_rdv_failures" to override. Fixes bug 24895; bugfix on 0.0.6.
o Minor feature (relay statistics): - Change relay bandwidth reporting stats interval from 4 hours to 24 hours in order to reduce the efficiency of guard discovery attacks. Fixes ticket 23856.
o Minor features (compatibility, OpenSSL): - Tor will now support TLS1.3 once OpenSSL 1.1.1 is released. Previous versions of Tor would not have worked with OpenSSL 1.1.1, since they neither disabled TLS 1.3 nor enabled any of the ciphersuites it requires. Now we enable the TLS 1.3 ciphersuites. Closes ticket 24978.
o Minor features (denial-of-service avoidance): - Make our OOM handler aware of the geoip client history cache so it doesn't fill up the memory. This check is important for IPv6 and our DoS mitigation subsystem. Closes ticket 25122.
o Minor features (fallback directory mirrors): - The fallback directory list has been re-generated based on the current status of the network. Tor uses fallback directories to bootstrap when it doesn't yet have up-to-date directory information. Closes ticket 24801. - Make the default DirAuthorityFallbackRate 0.1, so that clients prefer to bootstrap from fallback directory mirrors. This is a follow-up to 24679, which removed weights from the default fallbacks. Implements ticket 24681.
o Minor features (geoip): - Update geoip and geoip6 to the February 7 2018 Maxmind GeoLite2 Country database.
o Minor features (linux seccomp2 sandbox): - Update the sandbox rules so that they should now work correctly with Glibc 2.26. Closes ticket 24315.
o Minor bugfix (channel connection): - Use the actual observed address of an incoming relay connection, not the canonical address of the relay from its descriptor, when making decisions about how to handle the incoming connection. Fixes bug 24952; bugfix on 0.2.4.11-alpha. Patch by "ffmancera".
o Minor bugfix (directory authority): - Directory authorities, when refusing a descriptor from a rejected relay, now explicitly tell the relay (in its logs) to set a valid ContactInfo address and contact the bad-relays@ mailing list. Fixes bug 25170; bugfix on 0.2.9.1.
o Minor bugfixes (address selection): - When the fascist_firewall_choose_address_ functions don't find a reachable address, set the returned address to the null address and port. This is a precautionary measure, because some callers do not check the return value. Fixes bug 24736; bugfix on 0.2.8.2-alpha.
o Minor bugfixes (compilation): - Fix a signed/unsigned comparison warning introduced by our fix to TROVE-2017-009. Fixes bug 24480; bugfix on 0.2.5.16.
o Minor bugfixes (control port, linux seccomp2 sandbox): - Avoid a crash when attempting to use the seccomp2 sandbox together with the OwningControllerProcess feature. Fixes bug 24198; bugfix on 0.2.5.1-alpha.
o Minor bugfixes (denial-of-service, backport from 0.3.3.3-alpha): - Fix a possible crash on malformed consensus. If a consensus had contained an unparseable protocol line, it could have made clients and relays crash with a null-pointer exception. To exploit this issue, however, an attacker would need to be able to subvert the directory authority system. Fixes bug 25251; bugfix on 0.2.9.4-alpha. Also tracked as TROVE-2018-004.
o Minor bugfixes (memory usage): - When queuing DESTROY cells on a channel, only queue the circuit-id and reason fields: not the entire 514-byte cell. This fix should help mitigate any bugs or attacks that fill up these queues, and free more RAM for other uses. Fixes bug 24666; bugfix on 0.2.5.1-alpha.
o Minor bugfixes (network layer): - When closing a connection via close_connection_immediately(), we mark it as "not blocked on bandwidth", to prevent later calls from trying to unblock it, and give it permission to read. This fixes a backtrace warning that can happen on relays under various circumstances. Fixes bug 24167; bugfix on 0.1.0.1-rc.
o Minor bugfixes (OSX): - Don't exit the Tor process if setrlimit() fails to change the file limit (which can happen sometimes on some versions of OSX). Fixes bug 21074; bugfix on 0.0.9pre5.
o Minor bugfixes (path selection): - When selecting relays by bandwidth, avoid a rounding error that could sometimes cause load to be imbalanced incorrectly. Previously, we would always round upwards; now, we round towards the nearest integer. This had the biggest effect when a relay's weight adjustments should have given it weight 0, but it got weight 1 instead. Fixes bug 23318; bugfix on 0.2.4.3-alpha. - When calculating the fraction of nodes that have descriptors, and all nodes in the network have zero bandwidths, count the number of nodes instead. Fixes bug 23318; bugfix on 0.2.4.10-alpha. - Actually log the total bandwidth in compute_weighted_bandwidths(). Fixes bug 24170; bugfix on 0.2.4.3-alpha.
o Minor bugfixes (portability, msvc): - Fix a bug in the bit-counting parts of our timing-wheel code on MSVC. (Note that MSVC is still not a supported build platform, due to cryptographic timing channel risks.) Fixes bug 24633; bugfix on 0.2.9.1-alpha.
o Minor bugfixes (relay): - Make the internal channel_is_client() function look at what sort of connection handshake the other side used, rather than whether the other side ever sent a create_fast cell to us. Backports part of the fixes from bugs 22805 and 24898.
o Minor bugfixes (spec conformance, backport from 0.3.3.3-alpha): - Forbid "-0" as a protocol version. Fixes part of bug 25249; bugfix on 0.2.9.4-alpha. - Forbid UINT32_MAX as a protocol version. Fixes part of bug 25249; bugfix on 0.2.9.4-alpha.