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Tor Browser 3.6.6 and Tor 0.2.4.24 are released
by Roger Dingledine 27 Sep '14

27 Sep '14

The sixth pointfix release of the Tor Browser 3.6 series is available from the Tor Browser Project page and also from our distribution directory: https://www.torproject.org/download/download-easy.html https://www.torproject.org/dist/torbrowser/3.6.6/ This release features important security updates to Firefox: https://www.mozilla.org/security/known-vulnerabilities/firefoxESR.html#fire… Here is the complete changelog for 3.6.6: All Platforms Update Tor to tor-0.2.4.24 Update Firefox to 24.8.1esr Update NoScript to 2.6.8.42 Update HTTPS Everywhere to 4.0.1 Bug 12998: Prevent intermediate certs from being written to disk Update Torbutton to 1.6.12.3 Bug 13091: Use "Tor Browser" everywhere Bug 10804: Workaround fix for some cases of startup hang Linux Bug 9150: Make RPATH unavailable on Tor binary. ----------------------------------------------------------------------- Tor 0.2.4.24 fixes a bug that affects consistency and speed when connecting to hidden services, and it updates the location of one of the directory authorities. Changes in version 0.2.4.24 - 2014-09-22 o Major bugfixes: - Clients now send the correct address for their chosen rendezvous point when trying to access a hidden service. They used to send the wrong address, which would still work some of the time because they also sent the identity digest of the rendezvous point, and if the hidden service happened to try connecting to the rendezvous point from a relay that already had a connection open to it, the relay would reuse that connection. Now connections to hidden services should be more robust and faster. Also, this bug meant that clients were leaking to the hidden service whether they were on a little-endian (common) or big-endian (rare) system, which for some users might have reduced their anonymity. Fixes bug 13151; bugfix on 0.2.1.5-alpha. o Directory authority changes: - Change IP address for gabelmoo (v3 directory authority). o Minor features (geoip): - Update geoip and geoip6 to the August 7 2014 Maxmind GeoLite2 Country database.

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Tor security advisory: "relay early" traffic confirmation attack
by Roger Dingledine 30 Jul '14

30 Jul '14

SUMMARY: On July 4 2014 we found a group of relays that we assume were trying to deanonymize users. They appear to have been targeting people who operate or access Tor hidden services. The attack involved modifying Tor protocol headers to do traffic confirmation attacks. The attacking relays joined the network on January 30 2014, and we removed them from the network on July 4. While we don't know when they started doing the attack, users who operated or accessed hidden services from early February through July 4 should assume they were affected. Unfortunately, it's still unclear what "affected" includes. We know the attack looked for users who fetched hidden service descriptors, but the attackers likely were not able to see any application-level traffic (e.g. what pages were loaded or even whether users visited the hidden service they looked up). The attack probably also tried to learn who published hidden service descriptors, which would allow the attackers to learn the location of that hidden service. In theory the attack could also be used to link users to their destinations on normal Tor circuits too, but we found no evidence that the attackers operated any exit relays, making this attack less likely. And finally, we don't know how much data the attackers kept, and due to the way the attack was deployed (more details below), their protocol header modifications might have aided other attackers in deanonymizing users too. Relays should upgrade to a recent Tor release (0.2.4.23 or 0.2.5.6-alpha), to close the particular protocol vulnerability the attackers used -- but remember that preventing traffic confirmation in general remains an open research problem. Clients that upgrade (once new Tor Browser releases are ready) will take another step towards limiting the number of entry guards that are in a position to see their traffic, thus reducing the damage from future attacks like this one. Hidden service operators should consider changing the location of their hidden service. THE TECHNICAL DETAILS: We believe they used a combination of two classes of attacks: a traffic confirmation attack and a Sybil attack. A traffic confirmation attack is possible when the attacker controls or observes the relays on both ends of a Tor circuit and then compares traffic timing, volume, or other characteristics to conclude that the two relays are indeed on the same circuit. If the first relay in the circuit (called the "entry guard") knows the IP address of the user, and the last relay in the circuit knows the resource or destination she is accessing, then together they can deanonymize her. You can read more about traffic confirmation attacks, including pointers to many research papers, at this blog post from 2009: https://blog.torproject.org/blog/one-cell-enough The particular confirmation attack they used was an active attack where the relay on one end injects a signal into the Tor protocol headers, and then the relay on the other end reads the signal. These attacking relays were stable enough to get the HSDir ("suitable for hidden service directory") and Guard ("suitable for being an entry guard") consensus flags: https://gitweb.torproject.org/torspec.git/blob/HEAD:/dir-spec.txt#l1775 Then they injected the signal whenever they were used as a hidden service directory, and looked for an injected signal whenever they were used as an entry guard. The way they injected the signal was by sending sequences of "relay" vs "relay early" commands down the circuit, to encode the message they want to send. For background, Tor has two types of cells: link cells, which are intended for the adjacent relay in the circuit, and relay cells, which are passed to the other end of the circuit. https://gitweb.torproject.org/torspec.git/blob/HEAD:/tor-spec.txt#l364 In 2008 we added a new kind of relay cell, called a "relay early" cell, which is used to prevent people from building very long paths in the Tor network (very long paths can be used to induce congestion and aid in breaking anonymity): http://freehaven.net/anonbib/#congestion-longpaths https://gitweb.torproject.org/torspec.git/blob/HEAD:/proposals/110-avoid-in… But the fix for infinite-length paths introduced a problem with accessing hidden services: https://trac.torproject.org/projects/tor/ticket/1038 and one of the side effects of our fix for bug 1038 was that while we limit the number of outbound (away from the client) "relay early" cells on a circuit, we don't limit the number of inbound (towards the client) relay early cells: https://lists.torproject.org/pipermail/tor-commits/2009-July/014679.html So in summary, when Tor clients contacted an attacking relay in its role as a Hidden Service Directory to publish or retrieve a hidden service descriptor (steps 2 and 3 on https://www.torproject.org/docs/hidden-services), that relay would send the hidden service name (encoded as a pattern of relay and relay-early cells) back down the circuit. Other attacking relays, when they get chosen for the first hop of a circuit, would look for inbound relay-early cells (since nobody else sends them) and would thus learn which clients requested information about a hidden service. There are three important points about this attack: A) The attacker encoded the name of the hidden service in the injected signal (as opposed to, say, sending a random number and keeping a local list mapping random number to hidden service name). The encoded signal is encrypted as it is sent over the TLS channel between relays. However, this signal would be easy to read and interpret by anybody who runs a relay and receives the encoded traffic. And we might also worry about a global adversary (e.g. a large intelligence agency) that records Internet traffic at the entry guards and then tries to break Tor's link encryption. The way this attack was performed weakens Tor's anonymity against these other potential attackers too -- either while it was happening or after the fact if they have traffic logs. So if the attack was a research project (i.e. not intentionally malicious), it was deployed in an irresponsible way because it puts users at risk indefinitely into the future. (This concern is in addition to the general issue that it's probably unwise from a legal perspective for researchers to attack real users by modifying their traffic on one end and wiretapping it on the other. Tools like Shadow are great for testing Tor research ideas out in the lab: http://shadow.github.io/ ) B) This protocol header signal injection attack is actually pretty neat from a research perspective, in that it's a bit different from previous tagging attacks which targeted the application-level payload. Previous tagging attacks modified the payload at the entry guard, and then looked for a modified payload at the exit relay (which can see the decrypted payload). Those attacks don't work in the other direction (from the exit relay back towards the client), because the payload is still encrypted at the entry guard. But because this new approach modifies ("tags") the cell headers rather than the payload, every relay in the path can see the tag. C) We should remind readers that while this particular variant of the traffic confirmation attack allows high-confidence and efficient correlation, the general class of passive (statistical) traffic confirmation attacks remains unsolved and would likely have worked just fine here. So the good news is traffic confirmation attacks aren't new or surprising, but the bad news is that they still work. See https://blog.torproject.org/blog/one-cell-enough for more discussion. Then the second class of attack they used, in conjunction with their traffic confirmation attack, was a standard Sybil attack -- they signed up around 115 fast non-exit relays, all running on 50.7.0.0/16 or 204.45.0.0/16. Together these relays summed to about 6.4% of the Guard capacity in the network. Then, in part because of our current guard rotation parameters: https://blog.torproject.org/blog/improving-tors-anonymity-changing-guard-pa… these relays became entry guards for a significant chunk of users over their five months of operation. We actually noticed these relays when they joined the network, since the DocTor scanner reported them: https://lists.torproject.org/pipermail/tor-consensus-health/2014-January/00… https://gitweb.torproject.org/doctor.git We considered the set of new relays at the time, and made a decision that it wasn't that large a fraction of the network. It's clear there's room for improvement in terms of how to let the Tor network grow while also ensuring we maintain social connections with the operators of all large groups of relays. (In general having a widely diverse set of relay locations and relay operators, yet not allowing any bad relays in, seems like a hard problem; on the other hand our detection scripts did notice them in this case, so there's hope for a better solution here.) In response, we've taken the following short-term steps: 1) Removed the attacking relays from the network. 2) Put out a software update for relays to prevent "relay early" cells from being used this way. 3) Put out a software update that will (once enough clients have upgraded) let us tell clients to move to using one entry guard rather than three, to reduce exposure to relays over time. 4) Clients can tell whether they've received a relay or relay-cell. For expert users, the new Tor version warns you in your logs if a relay on your path injects any relay-early cells: look for the phrase "Received an inbound RELAY_EARLY cell". The following longer-term research areas remain: 5) Further growing the Tor network and diversity of relay operators, which will reduce the impact from an adversary of a given size. 6) Exploring better mechanisms, e.g. social connections, to limit the impact from a malicious set of relays. We've also formed a group to pay more attention to suspicious relays in the network: https://blog.torproject.org/blog/how-report-bad-relays 7) Further reducing exposure to guards over time, perhaps by extending the guard rotation lifetime: https://blog.torproject.org/blog/lifecycle-of-a-new-relay https://blog.torproject.org/blog/improving-tors-anonymity-changing-guard-pa… 8) Better understanding statistical traffic correlation attacks and whether padding or other approaches can mitigate them. 9) Improving the hidden service design, including making it harder for relays serving as hidden service directory points to learn what hidden service address they're handling: https://blog.torproject.org/blog/hidden-services-need-some-love OPEN QUESTIONS: Q1) Was this the Black Hat 2014 talk that got canceled recently? Q2) Did we find all the malicious relays? Q3) Did the malicious relays inject the signal at any points besides the HSDir position? Q4) What data did the attackers keep, and are they going to destroy it? How have they protected the data (if any) while storing it? Great questions. We spent several months trying to extract information from the researchers who were going to give the Black Hat talk, and eventually we did get some hints from them about how "relay early" cells could be used for traffic confirmation attacks, which is how we started looking for the attacks in the wild. They haven't answered our emails lately, so we don't know for sure, but it seems likely that the answer to Q1 is "yes". In fact, we hope they *were* the ones doing the attacks, since otherwise it means somebody else was. We don't yet know the answers to Q2, Q3, or Q4.

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Tor 0.2.4.23 is released
by Roger Dingledine 30 Jul '14

30 Jul '14

Tor 0.2.4.23 brings us a big step closer to slowing down the risk from guard rotation, and also backports several important fixes from the Tor 0.2.5 alpha release series. Changes in version 0.2.4.23 - 2014-07-28 o Major features: - Clients now look at the "usecreatefast" consensus parameter to decide whether to use CREATE_FAST or CREATE cells for the first hop of their circuit. This approach can improve security on connections where Tor's circuit handshake is stronger than the available TLS connection security levels, but the tradeoff is more computational load on guard relays. Implements proposal 221. Resolves ticket 9386. - Make the number of entry guards configurable via a new NumEntryGuards consensus parameter, and the number of directory guards configurable via a new NumDirectoryGuards consensus parameter. Implements ticket 12688. o Major bugfixes: - Fix a bug in the bounds-checking in the 32-bit curve25519-donna implementation that caused incorrect results on 32-bit implementations when certain malformed inputs were used along with a small class of private ntor keys. This bug does not currently appear to allow an attacker to learn private keys or impersonate a Tor server, but it could provide a means to distinguish 32-bit Tor implementations from 64-bit Tor implementations. Fixes bug 12694; bugfix on 0.2.4.8-alpha. Bug found by Robert Ransom; fix from Adam Langley. o Minor bugfixes: - Warn and drop the circuit if we receive an inbound 'relay early' cell. Those used to be normal to receive on hidden service circuits due to bug 1038, but the buggy Tor versions are long gone from the network so we can afford to resume watching for them. Resolves the rest of bug 1038; bugfix on 0.2.1.19. - Correct a confusing error message when trying to extend a circuit via the control protocol but we don't know a descriptor or microdescriptor for one of the specified relays. Fixes bug 12718; bugfix on 0.2.3.1-alpha. - Avoid an illegal read from stack when initializing the TLS module using a version of OpenSSL without all of the ciphers used by the v2 link handshake. Fixes bug 12227; bugfix on 0.2.4.8-alpha. Found by "starlight". o Minor features: - Update geoip and geoip6 to the July 10 2014 Maxmind GeoLite2 Country database.

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[ANN] Tor 0.2.4.22 is released (and so were 0.2.4.20 and 0.2.4.21)
by Nick Mathewson 04 Jun '14

04 Jun '14

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello, all! This is a slightly belated announcement for the release of 0.2.4.22. I'm including the release notes for Tor 0.2.4.20 and Tor 0.2.4.21 as well, since apparently they never made it onto this list. I've enlisted help from Colin to make sure that future stable release announcements make it to this list in a more timely manner (ideally, as soon as packages are built). TorBrowser releases will typically lag a little, as they follow their own release schedule. (Alpha releases will still be announced on tor-talk only.) Changes in version 0.2.4.22 - 2014-05-16 Tor 0.2.4.22 backports numerous high-priority fixes from the Tor 0.2.5 alpha release series. These include blocking all authority signing keys that may have been affected by the OpenSSL "heartbleed" bug, choosing a far more secure set of TLS ciphersuites by default, closing a couple of memory leaks that could be used to run a target relay out of RAM, and several others. o Major features (security, backport from 0.2.5.4-alpha): - Block authority signing keys that were used on authorities vulnerable to the "heartbleed" bug in OpenSSL (CVE-2014-0160). (We don't have any evidence that these keys _were_ compromised; we're doing this to be prudent.) Resolves ticket 11464. o Major bugfixes (security, OOM): - Fix a memory leak that could occur if a microdescriptor parse fails during the tokenizing step. This bug could enable a memory exhaustion attack by directory servers. Fixes bug 11649; bugfix on 0.2.2.6-alpha. o Major bugfixes (TLS cipher selection, backport from 0.2.5.4-alpha): - The relay ciphersuite list is now generated automatically based on uniform criteria, and includes all OpenSSL ciphersuites with acceptable strength and forward secrecy. Previously, we had left some perfectly fine ciphersuites unsupported due to omission or typo. Resolves bugs 11513, 11492, 11498, 11499. Bugs reported by 'cypherpunks'. Bugfix on 0.2.4.8-alpha. - Relays now trust themselves to have a better view than clients of which TLS ciphersuites are better than others. (Thanks to bug 11513, the relay list is now well-considered, whereas the client list has been chosen mainly for anti-fingerprinting purposes.) Relays prefer: AES over 3DES; then ECDHE over DHE; then GCM over CBC; then SHA384 over SHA256 over SHA1; and last, AES256 over AES128. Resolves ticket 11528. - Clients now try to advertise the same list of ciphersuites as Firefox 28. This change enables selection of (fast) GCM ciphersuites, disables some strange old ciphers, and stops advertising the ECDH (not to be confused with ECDHE) ciphersuites. Resolves ticket 11438. o Minor bugfixes (configuration, security): - When running a hidden service, do not allow TunneledDirConns 0: trying to set that option together with a hidden service would otherwise prevent the hidden service from running, and also make it publish its descriptors directly over HTTP. Fixes bug 10849; bugfix on 0.2.1.1-alpha. o Minor bugfixes (controller, backport from 0.2.5.4-alpha): - Avoid sending a garbage value to the controller when a circuit is cannibalized. Fixes bug 11519; bugfix on 0.2.3.11-alpha. o Minor bugfixes (exit relay, backport from 0.2.5.4-alpha): - Stop leaking memory when we successfully resolve a PTR record. Fixes bug 11437; bugfix on 0.2.4.7-alpha. o Minor bugfixes (bridge client, backport from 0.2.5.4-alpha): - Avoid 60-second delays in the bootstrapping process when Tor is launching for a second time while using bridges. Fixes bug 9229; bugfix on 0.2.0.3-alpha. o Minor bugfixes (relays and bridges, backport from 0.2.5.4-alpha): - Give the correct URL in the warning message when trying to run a relay on an ancient version of Windows. Fixes bug 9393. o Minor bugfixes (compilation): - Fix a compilation error when compiling with --disable-curve25519. Fixes bug 9700; bugfix on 0.2.4.17-rc. o Minor bugfixes: - Downgrade the warning severity for the the "md was still referenced 1 node(s)" warning. Tor 0.2.5.4-alpha has better code for trying to diagnose this bug, and the current warning in earlier versions of tor achieves nothing useful. Addresses warning from bug 7164. o Minor features (log verbosity, backport from 0.2.5.4-alpha): - When we run out of usable circuit IDs on a channel, log only one warning for the whole channel, and describe how many circuits there were on the channel. Fixes part of ticket 11553. o Minor features (security, backport from 0.2.5.4-alpha): - Decrease the lower limit of MaxMemInCellQueues to 256 MBytes (but leave the default at 8GBytes), to better support Raspberry Pi users. Fixes bug 9686; bugfix on 0.2.4.14-alpha. o Documentation (backport from 0.2.5.4-alpha): - Correctly document that we search for a system torrc file before looking in ~/.torrc. Fixes documentation side of 9213; bugfix on 0.2.3.18-rc. Changes in version 0.2.4.21 - 2014-02-28 Tor 0.2.4.21 further improves security against potential adversaries who find breaking 1024-bit crypto doable, and backports several stability and robustness patches from the 0.2.5 branch. o Major features (client security): - When we choose a path for a 3-hop circuit, make sure it contains at least one relay that supports the NTor circuit extension handshake. Otherwise, there is a chance that we're building a circuit that's worth attacking by an adversary who finds breaking 1024-bit crypto doable, and that chance changes the game theory. Implements ticket 9777. o Major bugfixes: - Do not treat streams that fail with reason END_STREAM_REASON_INTERNAL as indicating a definite circuit failure, since it could also indicate an ENETUNREACH connection error. Fixes part of bug 10777; bugfix on 0.2.4.8-alpha. o Code simplification and refactoring: - Remove data structures which were introduced to implement the CellStatistics option: they are now redundant with the new timestamp field in the regular packed_cell_t data structure, which we did in 0.2.4.18-rc in order to resolve bug 9093. Resolves ticket 10870. o Minor features: - Always clear OpenSSL bignums before freeing them -- even bignums that don't contain secrets. Resolves ticket 10793. Patch by Florent Daigniere. - Build without warnings under clang 3.4. (We have some macros that define static functions only some of which will get used later in the module. Starting with clang 3.4, these give a warning unless the unused attribute is set on them.) Resolves ticket 10904. - Update geoip and geoip6 files to the February 7 2014 Maxmind GeoLite2 Country database. o Minor bugfixes: - Set the listen() backlog limit to the largest actually supported on the system, not to the value in a header file. Fixes bug 9716; bugfix on every released Tor. - Treat ENETUNREACH, EACCES, and EPERM connection failures at an exit node as a NOROUTE error, not an INTERNAL error, since they can apparently happen when trying to connect to the wrong sort of netblocks. Fixes part of bug 10777; bugfix on 0.1.0.1-rc. - Fix build warnings about missing "a2x" comment when building the manpages from scratch on OpenBSD; OpenBSD calls it "a2x.py". Fixes bug 10929; bugfix on 0.2.2.9-alpha. Patch from Dana Koch. - Avoid a segfault on SIGUSR1, where we had freed a connection but did not entirely remove it from the connection lists. Fixes bug 9602; bugfix on 0.2.4.4-alpha. - Fix a segmentation fault in our benchmark code when running with Fedora's OpenSSL package, or any other OpenSSL that provides ECDH but not P224. Fixes bug 10835; bugfix on 0.2.4.8-alpha. - Turn "circuit handshake stats since last time" log messages into a heartbeat message. Fixes bug 10485; bugfix on 0.2.4.17-rc. o Documentation fixes: - Document that all but one DirPort entry must have the NoAdvertise flag set. Fixes bug 10470; bugfix on 0.2.3.3-alpha / 0.2.3.16-alpha. Changes in version 0.2.4.20 - 2013-12-22 Tor 0.2.4.20 fixes potentially poor random number generation for users who 1) use OpenSSL 1.0.0 or later, 2) set "HardwareAccel 1" in their torrc file, 3) have "Sandy Bridge" or "Ivy Bridge" Intel processors, and 4) have no state file in their DataDirectory (as would happen on first start). Users who generated relay or hidden service identity keys in such a situation should discard them and generate new ones. This release also fixes a logic error that caused Tor clients to build many more preemptive circuits than they actually need. o Major bugfixes: - Do not allow OpenSSL engines to replace the PRNG, even when HardwareAccel is set. The only default builtin PRNG engine uses the Intel RDRAND instruction to replace the entire PRNG, and ignores all attempts to seed it with more entropy. That's cryptographically stupid: the right response to a new alleged entropy source is never to discard all previously used entropy sources. Fixes bug 10402; works around behavior introduced in OpenSSL 1.0.0. Diagnosis and investigation thanks to "coderman" and "rl1987". - Fix assertion failure when AutomapHostsOnResolve yields an IPv6 address. Fixes bug 10465; bugfix on 0.2.4.7-alpha. - Avoid launching spurious extra circuits when a stream is pending. This fixes a bug where any circuit that _wasn't_ unusable for new streams would be treated as if it were, causing extra circuits to be launched. Fixes bug 10456; bugfix on 0.2.4.12-alpha. o Minor bugfixes: - Avoid a crash bug when starting with a corrupted microdescriptor cache file. Fixes bug 10406; bugfix on 0.2.2.6-alpha. - If we fail to dump a previously cached microdescriptor to disk, avoid freeing duplicate data later on. Fixes bug 10423; bugfix on 0.2.4.13-alpha. Spotted by "bobnomnom". -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQGVAwUBU45IaJEDl9iNKTGaAQKCvAv8CFVTBvwsHap8IpBT48S/sdybN0uL8L7N 1axQbgAbuTyyyskZaOTv/pp/4FvvOJ0ulCZfyrsXV7jQhsUNm1Ri9phWob2/sEpx 6Io9AVxw9W16mzduqlmxkdiVmvQNN17XTuPaYcjBtN2bbDGyrG6XtYjo03Lu3HUV xgKuaJR7eiked8G44slbccz80V1zmKq75YD4gFJgyBBNoS/0tmjh2zmjaE+7TeBq jEJyedFPVhhGHWg2PruDLeSgfKTIwA8KtJwAmJ7JwKNSX4LTFGz7MZrX77QdnZ3D FRDUuvGMVq6p5QGfsx59B9Uc6o8ox6UfnXYEqtzP9fDKPRvFNU7FqSV7Siu54Bk6 f/aY00IC05etz4X6t2NOtSCKAu7/Abd7zbYRLaW/v67/r6iaR6r/LVAILgJZA8jw acZGBaVov4ta/5sJcWLx/6iCD1VxtGkgk6TH399b1EGn9SFO4Exp5sGMLc4qiLEk 3hP+/YEYNx+yDz1IkupuwZDHa4iQtefh =du7v -----END PGP SIGNATURE-----

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Tor security advisory: OpenSSL flaw
by Roger Dingledine 10 Apr '14

10 Apr '14

A new OpenSSL vulnerability is out this week, which can be used to reveal memory to a connected client or server. Tor uses OpenSSL so all Tor users (clients, relays, etc) are potentially affected. You can read many more details about the Tor impact on our blog post: https://blog.torproject.org/blog/openssl-bug-cve-2014-0160 We have released an updated Tor Browser Bundle: https://blog.torproject.org/blog/tor-browser-354-released --Roger

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Tor 0.2.4.19 is released
by Roger Dingledine 21 Dec '13

21 Dec '13

The Tor 0.2.4 release series is dedicated to the memory of Aaron Swartz (1986-2013). Aaron worked on diverse projects including helping to guide Creative Commons, playing a key role in stopping SOPA/PIPA, bringing transparency to the U.S. government's PACER documents, and contributing design and development for Tor and Tor2Web. Aaron was one of the latest martyrs in our collective fight for civil liberties and human rights, and his death is all the more painful because he was one of us. Tor 0.2.4.19, the first stable release in the 0.2.4 branch, features a new circuit handshake and link encryption that use ECC to provide better security and efficiency; makes relays better manage circuit creation requests; uses "directory guards" to reduce client enumeration risks; makes bridges collect and report statistics about the pluggable transports they support; cleans up and improves our geoip database; gets much closer to IPv6 support for clients, bridges, and relays; makes directory authorities use measured bandwidths rather than advertised ones when computing flags and thresholds; disables client-side DNS caching to reduce tracking risks; and fixes a big bug in bridge reachability testing. This release introduces two new design abstractions in the code: a new "channel" abstraction between circuits and or_connections to allow for implementing alternate relay-to-relay transports, and a new "circuitmux" abstraction storing the queue of circuits for a channel. The release also includes many stability, security, and privacy fixes. This new Tor release coincides with the new Tor Browser Bundle 3.5, which switches to Firefox 24 and includes many other fixes: https://blog.torproject.org/blog/tor-browser-bundle-35-released https://www.torproject.org/download/download Changes in version 0.2.4.19 - 2013-12-11 o Major features (new circuit handshake): - Tor now supports a new circuit extension handshake designed by Ian Goldberg, Douglas Stebila, and Berkant Ustaoglu. Our original circuit extension handshake, later called "TAP", was a bit slow (especially on the relay side), had a fragile security proof, and used weaker keys than we'd now prefer. The new circuit handshake uses Dan Bernstein's "curve25519" elliptic-curve Diffie-Hellman function, making it significantly more secure than the older handshake, and significantly faster. Tor can use one of two built-in pure-C curve25519-donna implementations by Adam Langley, or it can link against the "nacl" library for a tuned version if present. The built-in version is very fast for 64-bit systems when building with GCC. The built-in 32-bit version is still faster than the old TAP protocol, but using libnacl is better on most such hosts. Implements proposal 216; closes ticket 7202. o Major features (better link encryption): - Relays can now enable the ECDHE TLS ciphersuites when available and appropriate. These ciphersuites let us negotiate forward-secure TLS secret keys more safely and more efficiently than with our previous use of Diffie-Hellman modulo a 1024-bit prime. By default, public relays prefer the (faster) P224 group, and bridges prefer the (more common) P256 group; you can override this with the TLSECGroup option. This feature requires clients running 0.2.3.17-beta or later, and requires both sides to be running OpenSSL 1.0.0 or later with ECC support. OpenSSL 1.0.1, with the compile-time option "enable-ec_nistp_64_gcc_128", is highly recommended. Implements the relay side of proposal 198; closes ticket 7200. - Re-enable TLS 1.1 and 1.2 when built with OpenSSL 1.0.1e or later. Resolves ticket 6055. (OpenSSL before 1.0.1 didn't have TLS 1.1 or 1.2, and OpenSSL from 1.0.1 through 1.0.1d had bugs that prevented renegotiation from working with TLS 1.1 or 1.2, so we had disabled them to solve bug 6033.) o Major features (relay performance): - Instead of limiting the number of queued onionskins (aka circuit create requests) to a fixed, hard-to-configure number, we limit the size of the queue based on how many we expect to be able to process in a given amount of time. We estimate the time it will take to process an onionskin based on average processing time of previous onionskins. Closes ticket 7291. You'll never have to configure MaxOnionsPending again. - Relays process the new "NTor" circuit-level handshake requests with higher priority than the old "TAP" circuit-level handshake requests. We still process some TAP requests to not totally starve 0.2.3 clients when NTor becomes popular. A new consensus parameter "NumNTorsPerTAP" lets us tune the balance later if we need to. Implements ticket 9574. o Major features (client bootstrapping resilience): - Add a new "FallbackDir" torrc option to use when we can't use a directory mirror from the consensus (either because we lack a consensus, or because they're all down). Currently, all authorities are fallbacks by default, and there are no other default fallbacks, but that will change. This option will allow us to give clients a longer list of servers to try to get a consensus from when first connecting to the Tor network, and thereby reduce load on the directory authorities. Implements proposal 206, "Preconfigured directory sources for bootstrapping". We also removed the old "FallbackNetworkstatus" option, since we never got it working well enough to use it. Closes bug 572. - If we have no circuits open, use a relaxed timeout (the 95th-percentile cutoff) until a circuit succeeds. This heuristic should allow Tor to succeed at building circuits even when the network connection drastically changes. Should help with bug 3443. o Major features (use of guards): - Support directory guards (proposal 207): when possible, clients now use their entry guards for non-anonymous directory requests. This can help prevent client enumeration. Note that this behavior only works when we have a usable consensus directory, and when options about what to download are more or less standard. In the future we should re-bootstrap from our guards, rather than re-bootstrapping from the preconfigured list of directory sources that ships with Tor. Resolves ticket 6526. - Raise the default time that a client keeps an entry guard from "1-2 months" to "2-3 months", as suggested by Tariq Elahi's WPES 2012 paper. (We would make it even longer, but we need better client load balancing first.) Also, make the guard lifetime controllable via a new GuardLifetime torrc option and a GuardLifetime consensus parameter. Start of a fix for bug 8240; bugfix on 0.1.1.11-alpha. o Major features (bridges with pluggable transports): - Bridges now report the pluggable transports they support to the bridge authority, so it can pass the supported transports on to bridgedb and/or eventually do reachability testing. Implements ticket 3589. - Automatically forward the TCP ports of pluggable transport proxies using tor-fw-helper if PortForwarding is enabled. Implements ticket 4567. o Major features (geoip database): - Maxmind began labelling Tor relays as being in country "A1", which breaks by-country node selection inside Tor. Now we use a script to replace "A1" ("Anonymous Proxy") entries in our geoip file with real country codes. This script fixes about 90% of "A1" entries automatically and uses manual country code assignments to fix the remaining 10%. See src/config/README.geoip for details. Fixes bug 6266. - Add GeoIP database for IPv6 addresses. The new config option is GeoIPv6File. - Update to the October 2 2013 Maxmind GeoLite Country database. o Major features (IPv6): - Clients who set "ClientUseIPv6 1" may connect to entry nodes over IPv6. Set "ClientPreferIPv6ORPort 1" to make this even more likely to happen. Implements ticket 5535. - All kind of relays, not just bridges, can now advertise an IPv6 OR port. Implements ticket 6362. - Relays can now exit to IPv6 addresses: make sure that you have IPv6 connectivity, then set the IPv6Exit flag to 1. Also make sure your exit policy reads as you would like: the address * applies to all address families, whereas *4 is IPv4 address only, and *6 is IPv6 addresses only. On the client side, you'll need to wait for enough exits to support IPv6, apply the "IPv6Traffic" flag to a SocksPort, and use Socks5. Closes ticket 5547, implements proposal 117 as revised in proposal 208. - Bridge authorities now accept IPv6 bridge addresses and include them in network status documents. Implements ticket 5534. - Directory authorities vote on IPv6 OR ports. Implements ticket 6363. o Major features (directory authorities): - Directory authorities now prefer using measured bandwidths to advertised ones when computing flags and thresholds. Resolves ticket 8273. - Directory authorities that vote measured bandwidths about more than a threshold number of relays now treat relays with unmeasured bandwidths as having bandwidth 0 when computing their flags. Resolves ticket 8435. - Directory authorities now support a new consensus method (17) where they cap the published bandwidth of relays for which insufficient bandwidth measurements exist. Fixes part of bug 2286. - Directory authorities that set "DisableV2DirectoryInfo_ 1" no longer serve any v2 directory information. Now we can test disabling the old deprecated v2 directory format, and see whether doing so has any effect on network load. Begins to fix bug 6783. o Major features (build and portability): - Switch to a nonrecursive Makefile structure. Now instead of each Makefile.am invoking other Makefile.am's, there is a master Makefile.am that includes the others. This change makes our build process slightly more maintainable, and improves parallelism for building with make -j. Original patch by Stewart Smith; various fixes by Jim Meyering. - Where available, we now use automake's "silent" make rules by default, so that warnings are easier to spot. You can get the old behavior with "make V=1". Patch by Stewart Smith for ticket 6522. - Resume building correctly with MSVC and Makefile.nmake. This patch resolves numerous bugs and fixes reported by ultramage, including 7305, 7308, 7309, 7310, 7312, 7313, 7315, 7316, and 7669. o Security features: - Switch to a completely time-invariant approach for picking nodes weighted by bandwidth. Our old approach would run through the part of the loop after it had made its choice slightly slower than it ran through the part of the loop before it had made its choice. Addresses ticket 6538. - Disable the use of Guard nodes when in Tor2WebMode. Guard usage by tor2web clients allows hidden services to identify tor2web clients through their repeated selection of the same rendezvous and introduction point circuit endpoints (their guards). Resolves ticket 6888. o Major bugfixes (relay denial of service): - When we have too much memory queued in circuits (according to a new MaxMemInCellQueues option), close the circuits that have the oldest queued cells, on the theory that those are most responsible for us running low on memory. This prevents us from running out of memory as a relay if circuits fill up faster than they can be drained. Fixes bugs 9063 and 9093; bugfix on the 54th commit of Tor. This bug is a further fix beyond bug 6252, whose fix was merged into 0.2.3.21-rc. - Reject bogus create and relay cells with 0 circuit ID or 0 stream ID: these could be used to create unexpected streams and circuits which would count as "present" to some parts of Tor but "absent" to others, leading to zombie circuits and streams or to a bandwidth denial-of-service. Fixes bug 7889; bugfix on every released version of Tor. Reported by "oftc_must_be_destroyed". - Avoid a bug where our response to TLS renegotiation under certain network conditions could lead to a busy-loop, with 100% CPU consumption. Fixes bug 5650; bugfix on 0.2.0.16-alpha. o Major bugfixes (asserts, crashes, leaks): - Prevent the get_freelists() function from running off the end of the list of freelists if it somehow gets an unrecognized allocation. Fixes bug 8844; bugfix on 0.2.0.16-alpha. Reported by eugenis. - Avoid a memory leak where we would leak a consensus body when we find that a consensus which we couldn't previously verify due to missing certificates is now verifiable. Fixes bug 8719; bugfix on 0.2.0.10-alpha. - If we are unable to save a microdescriptor to the journal, do not drop it from memory and then reattempt downloading it. Fixes bug 9645; bugfix on 0.2.2.6-alpha. - Fix an assertion failure that would occur when disabling the ORPort setting on a running Tor process while accounting was enabled. Fixes bug 6979; bugfix on 0.2.2.18-alpha. - Avoid an assertion failure on OpenBSD (and perhaps other BSDs) when an exit connection with optimistic data succeeds immediately rather than returning EINPROGRESS. Fixes bug 9017; bugfix on 0.2.3.1-alpha. - Fix a memory leak that would occur whenever a configuration option changed. Fixes bug 8718; bugfix on 0.2.3.3-alpha. o Major bugfixes (relay rate limiting): - When a TLS write is partially successful but incomplete, remember that the flushed part has been flushed, and notice that bytes were actually written. Reported and fixed pseudonymously. Fixes bug 7708; bugfix on Tor 0.1.0.5-rc. - Raise the default BandwidthRate/BandwidthBurst values from 5MB/10MB to 1GB/1GB. The previous defaults were intended to be "basically infinite", but it turns out they're now limiting our 100mbit+ relays and bridges. Fixes bug 6605; bugfix on 0.2.0.10-alpha (the last time we raised it). - No longer stop reading or writing on cpuworker connections when our rate limiting buckets go empty. Now we should handle circuit handshake requests more promptly. Resolves bug 9731. o Major bugfixes (client-side privacy): - When we mark a circuit as unusable for new circuits, have it continue to be unusable for new circuits even if MaxCircuitDirtiness is increased too much at the wrong time, or the system clock jumps backwards. Fixes bug 6174; bugfix on 0.0.2pre26. - If ClientDNSRejectInternalAddresses ("do not believe DNS queries which have resolved to internal addresses") is set, apply that rule to IPv6 as well. Fixes bug 8475; bugfix on 0.2.0.7-alpha. - When an exit relay rejects a stream with reason "exit policy", but we only know an exit policy summary (e.g. from the microdesc consensus) for it, do not mark the relay as useless for all exiting. Instead, mark just the circuit as unsuitable for that particular address. Fixes part of bug 7582; bugfix on 0.2.3.2-alpha. o Major bugfixes (stream isolation): - Allow applications to get proper stream isolation with IsolateSOCKSAuth. Many SOCKS5 clients that want to offer username/password authentication also offer "no authentication". Tor had previously preferred "no authentication", so the applications never actually sent Tor their auth details. Now Tor selects username/password authentication if it's offered. You can disable this behavior on a per-SOCKSPort basis via PreferSOCKSNoAuth. Fixes bug 8117; bugfix on 0.2.3.3-alpha. - Follow the socks5 protocol when offering username/password authentication. The fix for bug 8117 exposed this bug, and it turns out real-world applications like Pidgin do care. Bugfix on 0.2.3.2-alpha; fixes bug 8879. o Major bugfixes (client circuit building): - Alter circuit build timeout measurement to start at the point where we begin the CREATE/CREATE_FAST step (as opposed to circuit initialization). This should make our timeout measurements more uniform. Previously, we were sometimes including ORconn setup time in our circuit build time measurements. Should resolve bug 3443. - If the circuit build timeout logic is disabled (via the consensus, or because we are an authority), then don't build testing circuits. Fixes bug 9657; bugfix on 0.2.2.14-alpha. o Major bugfixes (client-side DNS): - Turn off the client-side DNS cache by default. Updating and using the DNS cache is now configurable on a per-client-port level. SOCKSPort, DNSPort, etc lines may now contain {No,}Cache{IPv4,IPv6,}DNS lines to indicate that we shouldn't cache these types of DNS answers when we receive them from an exit node in response to an application request on this port, and {No,}UseCached{IPv4,IPv6,DNS} lines to indicate that if we have cached DNS answers of these types, we shouldn't use them. It's potentially risky to use cached DNS answers at the client, since doing so can indicate to one exit what answers we've gotten for DNS lookups in the past. With IPv6, this becomes especially problematic. Using cached DNS answers for requests on the same circuit would present less linkability risk, since all traffic on a circuit is already linkable, but it would also provide little performance benefit: the exit node caches DNS replies too. Implements a simplified version of Proposal 205. Implements ticket 7570. o Major bugfixes (hidden service privacy): - Limit hidden service descriptors to at most ten introduction points, to slow one kind of guard enumeration. Fixes bug 9002; bugfix on 0.1.1.11-alpha. o Major bugfixes (directory fetching): - If the time to download the next old-style networkstatus is in the future, do not decline to consider whether to download the next microdescriptor networkstatus. Fixes bug 9564; bugfix on 0.2.3.14-alpha. - We used to always request authority certificates by identity digest, meaning we'd get the newest one even when we wanted one with a different signing key. Then we would complain about being given a certificate we already had, and never get the one we really wanted. Now we use the "fp-sk/" resource as well as the "fp/" resource to request the one we want. Fixes bug 5595; bugfix on 0.2.0.8-alpha. o Major bugfixes (bridge reachability): - Bridges now send AUTH_CHALLENGE cells during their v3 handshakes; previously they did not, which prevented them from receiving successful connections from relays for self-test or bandwidth testing. Also, when a relay is extending a circuit to a bridge, it needs to send a NETINFO cell, even when the bridge hasn't sent an AUTH_CHALLENGE cell. Fixes bug 9546; bugfix on 0.2.3.6-alpha. o Major bugfixes (control interface): - When receiving a new configuration file via the control port's LOADCONF command, do not treat the defaults file as absent. Fixes bug 9122; bugfix on 0.2.3.9-alpha. o Major bugfixes (directory authorities): - Stop marking every relay as having been down for one hour every time we restart a directory authority. These artificial downtimes were messing with our Stable and Guard flag calculations. Fixes bug 8218 (introduced by the fix for 1035). Bugfix on 0.2.2.23-alpha. - When computing directory thresholds, ignore any rejected-as-sybil nodes during the computation so that they can't influence Fast, Guard, etc. (We should have done this for proposal 109.) Fixes bug 8146. - When marking a node as a likely sybil, reset its uptime metrics to zero, so that it cannot time towards getting marked as Guard, Stable, or HSDir. (We should have done this for proposal 109.) Fixes bug 8147. - Fix a bug in the voting algorithm that could yield incorrect results when a non-naming authority declared too many flags. Fixes bug 9200; bugfix on 0.2.0.3-alpha. o Internal abstraction features: - Introduce new channel_t abstraction between circuits and or_connection_t to allow for implementing alternate OR-to-OR transports. A channel_t is an abstract object which can either be a cell-bearing channel, which is responsible for authenticating and handshaking with the remote OR and transmitting cells to and from it, or a listening channel, which spawns new cell-bearing channels at the request of remote ORs. Implements part of ticket 6465. - Make a channel_tls_t subclass of channel_t, adapting it to the existing or_connection_t code. The V2/V3 protocol handshaking code which formerly resided in command.c has been moved below the channel_t abstraction layer and may be found in channeltls.c now. Implements the rest of ticket 6465. - Introduce new circuitmux_t storing the queue of circuits for a channel; this encapsulates and abstracts the queue logic and circuit selection policy, and allows the latter to be overridden easily by switching out a policy object. The existing EWMA behavior is now implemented as a circuitmux_policy_t. Resolves ticket 6816. o New build requirements: - Tor now requires OpenSSL 0.9.8 or later. OpenSSL 1.0.0 or later is strongly recommended. - Tor maintainers now require Automake version 1.9 or later to build Tor from the Git repository. (Automake is not required when building from a source distribution.) o Minor features (protocol): - No longer include the "opt" prefix when generating routerinfos or v2 directories: it has been needless since Tor 0.1.2. Closes ticket 5124. - Reject EXTEND cells sent to nonexistent streams. According to the spec, an EXTEND cell sent to _any_ nonzero stream ID is invalid, but we were only checking for stream IDs that were currently in use. Found while hunting for more instances of bug 6271. Bugfix on 0.0.2pre8, which introduced incremental circuit construction. - Tor relays and clients now support a better CREATE/EXTEND cell format, allowing the sender to specify multiple address, identity, and handshake types. Implements Robert Ransom's proposal 200; closes ticket 7199. - Reject as invalid most directory objects containing a NUL. Belt-and-suspender fix for bug 8037. o Minor features (security): - Clear keys and key-derived material left on the stack in rendservice.c and rendclient.c. Check return value of crypto_pk_write_private_key_to_string() in rend_service_load_keys(). These fixes should make us more forward-secure against cold-boot attacks and the like. Fixes bug 2385. - Use our own weak RNG when we need a weak RNG. Windows's rand() and Irix's random() only return 15 bits; Solaris's random() returns more bits but its RAND_MAX says it only returns 15, and so on. Motivated by the fix for bug 7801; bugfix on 0.2.2.20-alpha. o Minor features (control protocol): - Add a "GETINFO signal/names" control port command. Implements ticket 3842. - Provide default values for all options via "GETINFO config/defaults". Implements ticket 4971. - Allow an optional $ before the node identity digest in the controller command GETINFO ns/id/<identity>, for consistency with md/id/<identity> and desc/id/<identity>. Resolves ticket 7059. - Add CACHED keyword to ADDRMAP events in the control protocol to indicate whether a DNS result will be cached or not. Resolves ticket 8596. - Generate bootstrapping status update events correctly when fetching microdescriptors. Fixes bug 9927. o Minor features (path selection): - When deciding whether we have enough descriptors to build circuits, instead of looking at raw relay counts, look at which fraction of (bandwidth-weighted) paths we're able to build. This approach keeps clients from building circuits if their paths are likely to stand out statistically. The default fraction of paths needed is taken from the consensus directory; you can override it with the new PathsNeededToBuildCircuits option. Fixes ticket 5956. - When any country code is listed in ExcludeNodes or ExcludeExitNodes, and we have GeoIP information, also exclude all nodes with unknown countries "??" and "A1". This behavior is controlled by the new GeoIPExcludeUnknown option: you can make such nodes always excluded with "GeoIPExcludeUnknown 1", and disable the feature with "GeoIPExcludeUnknown 0". Setting "GeoIPExcludeUnknown auto" gets you the default behavior. Implements feature 7706. o Minor features (hidden services): - Improve circuit build timeout handling for hidden services. In particular: adjust build timeouts more accurately depending upon the number of hop-RTTs that a particular circuit type undergoes. Additionally, launch intro circuits in parallel if they timeout, and take the first one to reply as valid. - The Tor client now ignores sub-domain components of a .onion address. This change makes HTTP "virtual" hosting possible: http://foo.aaaaaaaaaaaaaaaa.onion/ and http://bar.aaaaaaaaaaaaaaaa.onion/ can be two different websites hosted on the same hidden service. Implements proposal 204. - Enable Tor to read configuration, state, and key information from a FIFO. Previously Tor would only read from files with a positive stat.st_size. Code from meejah; fixes bug 6044. o Minor features (clients): - Teach bridge-using clients to avoid 0.2.2.x bridges when making microdescriptor-related dir requests, and only fall back to normal descriptors if none of their bridges can handle microdescriptors (as opposed to the fix in ticket 4013, which caused them to fall back to normal descriptors if *any* of their bridges preferred them). Resolves ticket 4994. - Tweak tor-fw-helper to accept an arbitrary amount of arbitrary TCP ports to forward. In the past it only accepted two ports: the ORPort and the DirPort. o Minor features (protecting client timestamps): - Clients no longer send timestamps in their NETINFO cells. These were not used for anything, and they provided one small way for clients to be distinguished from each other as they moved from network to network or behind NAT. Implements part of proposal 222. - Clients now round timestamps in INTRODUCE cells down to the nearest 10 minutes. If a new Support022HiddenServices option is set to 0, or if it's set to "auto" and the feature is disabled in the consensus, the timestamp is sent as 0 instead. Implements part of proposal 222. - Stop sending timestamps in AUTHENTICATE cells. This is not such a big deal from a security point of view, but it achieves no actual good purpose, and isn't needed. Implements part of proposal 222. - Reduce down accuracy of timestamps in hidden service descriptors. Implements part of proposal 222. o Minor features (bridges): - Make bridge relays check once a minute for whether their IP address has changed, rather than only every 15 minutes. Resolves bugs 1913 and 1992. - Bridge statistics now count bridge clients connecting over IPv6: bridge statistics files now list "bridge-ip-versions" and extra-info documents list "geoip6-db-digest". The control protocol "CLIENTS_SEEN" and "ip-to-country" queries now support IPv6. Initial implementation by "shkoo", addressing ticket 5055. - Add a new torrc option "ServerTransportListenAddr" to let bridge operators select the address where their pluggable transports will listen for connections. Resolves ticket 7013. - Randomize the lifetime of our SSL link certificate, so censors can't use the static value for filtering Tor flows. Resolves ticket 8443; related to ticket 4014 which was included in 0.2.2.33. o Minor features (relays): - Option OutboundBindAddress can be specified multiple times and accepts IPv6 addresses. Resolves ticket 6876. o Minor features (IPv6, client side): - AutomapHostsOnResolve now supports IPv6 addresses. By default, we prefer to hand out virtual IPv6 addresses, since there are more of them and we can't run out. To override this behavior and make IPv4 addresses preferred, set NoPreferIPv6Automap on whatever SOCKSPort or DNSPort you're using for resolving. Implements ticket 7571. - AutomapHostsOnResolve responses are now randomized, to avoid annoying situations where Tor is restarted and applications connect to the wrong addresses. - Never try more than 1000 times to pick a new virtual address when AutomapHostsOnResolve is set. That's good enough so long as we aren't close to handing out our entire virtual address space; if you're getting there, it's best to switch to IPv6 virtual addresses anyway. o Minor features (IPv6, relay/authority side): - New config option "AuthDirHasIPv6Connectivity 1" that directory authorities should set if they have IPv6 connectivity and want to do reachability tests for IPv6 relays. Implements feature 5974. - A relay with an IPv6 OR port now sends that address in NETINFO cells (in addition to its other address). Implements ticket 6364. o Minor features (directory authorities): - Directory authorities no long accept descriptors for any version of Tor before 0.2.2.35, or for any 0.2.3 release before 0.2.3.10-alpha. These versions are insecure, unsupported, or both. Implements ticket 6789. - When directory authorities are computing thresholds for flags, never let the threshold for the Fast flag fall below 4096 bytes. Also, do not consider nodes with extremely low bandwidths when deciding thresholds for various directory flags. This change should raise our threshold for Fast relays, possibly in turn improving overall network performance; see ticket 1854. Resolves ticket 8145. - Directory authorities now include inside each vote a statement of the performance thresholds they used when assigning flags. Implements ticket 8151. - Add an "ignoring-advertised-bws" boolean to the flag-threshold lines in directory authority votes to describe whether they have enough measured bandwidths to ignore advertised (relay descriptor) bandwidth claims. Resolves ticket 8711. o Minor features (path bias detection): - Path Use Bias: Perform separate accounting for successful circuit use. Keep separate statistics on stream attempt rates versus stream success rates for each guard. Provide configurable thresholds to determine when to emit log messages or disable use of guards that fail too many stream attempts. Resolves ticket 7802. - Create three levels of Path Bias log messages, as opposed to just two. These are configurable via consensus as well as via the torrc options PathBiasNoticeRate, PathBiasWarnRate, PathBiasExtremeRate. The default values are 0.70, 0.50, and 0.30 respectively. - Separate the log message levels from the decision to drop guards, which also is available via torrc option PathBiasDropGuards. PathBiasDropGuards still defaults to 0 (off). - Deprecate PathBiasDisableRate in favor of PathBiasDropGuards in combination with PathBiasExtremeRate. - Increase the default values for PathBiasScaleThreshold and PathBiasCircThreshold from (200, 20) to (300, 150). - Add in circuit usage accounting to path bias. If we try to use a built circuit but fail for any reason, it counts as path bias. Certain classes of circuits where the adversary gets to pick your destination node are exempt from this accounting. Usage accounting can be specifically disabled via consensus parameter or torrc. - Convert all internal path bias state to double-precision floating point, to avoid roundoff error and other issues. - Only record path bias information for circuits that have completed *two* hops. Assuming end-to-end tagging is the attack vector, this makes us more resilient to ambient circuit failure without any detection capability loss. o Minor features (build): - Tor now builds correctly on Bitrig, an OpenBSD fork. Patch from dhill. Resolves ticket 6982. - Compile on win64 using mingw64. Fixes bug 7260; patches from "yayooo". - Work correctly on Unix systems where EAGAIN and EWOULDBLOCK are separate error codes; or at least, don't break for that reason. Fixes bug 7935. Reported by "oftc_must_be_destroyed". o Build improvements (autotools): - Warn if building on a platform with an unsigned time_t: there are too many places where Tor currently assumes that time_t can hold negative values. We'd like to fix them all, but probably some will remain. - Do not report status verbosely from autogen.sh unless the -v flag is specified. Fixes issue 4664. Patch from Onizuka. - Detect and reject attempts to build Tor with threading support when OpenSSL has been compiled without threading support. Fixes bug 6673. - Try to detect if we are ever building on a platform where memset(...,0,...) does not set the value of a double to 0.0. Such platforms are permitted by the C standard, though in practice they're pretty rare (since IEEE 754 is nigh-ubiquitous). We don't currently support them, but it's better to detect them and fail than to perform erroneously. - We no longer warn so much when generating manpages from their asciidoc source. - Use Ville Laurikari's implementation of AX_CHECK_SIGN() to determine the signs of types during autoconf. This is better than our old approach, which didn't work when cross-compiling. o Minor features (log messages, warnings): - Detect when we're running with a version of OpenSSL other than the one we compiled with. This conflict has occasionally given people hard-to-track-down errors. - Warn users who run hidden services on a Tor client with UseEntryGuards disabled that their hidden services will be vulnerable to http://freehaven.net/anonbib/#hs-attack06 (the attack which motivated Tor to support entry guards in the first place). Resolves ticket 6889. - Warn when we are binding low ports when hibernation is enabled; previously we had warned when we were _advertising_ low ports with hibernation enabled. Fixes bug 7285; bugfix on 0.2.3.9-alpha. - Issue a warning when running with the bufferevents backend enabled. It's still not stable, and people should know that they're likely to hit unexpected problems. Closes ticket 9147. o Minor features (log messages, notices): - Refactor resolve_my_address() so it returns the method by which we decided our public IP address (explicitly configured, resolved from explicit hostname, guessed from interfaces, learned by gethostname). Now we can provide more helpful log messages when a relay guesses its IP address incorrectly (e.g. due to unexpected lines in /etc/hosts). Resolves ticket 2267. - Track how many "TAP" and "NTor" circuit handshake requests we get, and how many we complete, and log it every hour to help relay operators follow trends in network load. Addresses ticket 9658. o Minor features (log messages, diagnostics): - If we fail to free a microdescriptor because of bug 7164, log the filename and line number from which we tried to free it. - We compute the overhead from passing onionskins back and forth to cpuworkers, and report it when dumping statistics in response to SIGUSR1. Supports ticket 7291. - Add another diagnostic to the heartbeat message: track and log overhead that TLS is adding to the data we write. If this is high, we are sending too little data to SSL_write at a time. Diagnostic for bug 7707. - Log packaged cell fullness as part of the heartbeat message. Diagnosis to try to determine the extent of bug 7743. - Add more detail to a log message about relaxed timeouts, to help track bug 7799. - When learning a fingerprint for a bridge, log its corresponding transport type. Implements ticket 7896. - Warn more aggressively when flushing microdescriptors to a microdescriptor cache fails, in an attempt to mitigate bug 8031, or at least make it more diagnosable. - Improve the log message when "Bug/attack: unexpected sendme cell from client" occurs, to help us track bug 8093. - Improve debugging output to help track down bug 8185 ("Bug: outgoing relay cell has n_chan==NULL. Dropping.") o Minor features (log messages, quieter bootstrapping): - Log fewer lines at level "notice" about our OpenSSL and Libevent versions and capabilities when everything is going right. Resolves part of ticket 6736. - Omit the first heartbeat log message, because it never has anything useful to say, and it clutters up the bootstrapping messages. Resolves ticket 6758. - Don't log about reloading the microdescriptor cache at startup. Our bootstrap warnings are supposed to tell the user when there's a problem, and our bootstrap notices say when there isn't. Resolves ticket 6759; bugfix on 0.2.2.6-alpha. - Don't log "I learned some more directory information" when we're reading cached directory information. Reserve it for when new directory information arrives in response to a fetch. Resolves ticket 6760. - Don't complain about bootstrapping problems while hibernating. These complaints reflect a general code problem, but not one with any problematic effects (no connections are actually opened). Fixes part of bug 7302; bugfix on 0.2.3.2-alpha. o Minor features (testing): - In our testsuite, create temporary directories with a bit more entropy in their name to make name collisions less likely. Fixes bug 8638. - Add benchmarks for DH (1024-bit multiplicative group) and ECDH (P-256) Diffie-Hellman handshakes to src/or/bench. - Add benchmark functions to test onion handshake performance. o Renamed options: - The DirServer option is now DirAuthority, for consistency with current naming patterns. You can still use the old DirServer form. o Minor bugfixes (protocol): - Fix the handling of a TRUNCATE cell when it arrives while the circuit extension is in progress. Fixes bug 7947; bugfix on 0.0.7.1. - When a Tor client gets a "truncated" relay cell, the first byte of its payload specifies why the circuit was truncated. We were ignoring this 'reason' byte when tearing down the circuit, resulting in the controller not being told why the circuit closed. Now we pass the reason from the truncated cell to the controller. Bugfix on 0.1.2.3-alpha; fixes bug 7039. - Fix a misframing issue when reading the version numbers in a VERSIONS cell. Previously we would recognize [00 01 00 02] as 'version 1, version 2, and version 0x100', when it should have only included versions 1 and 2. Fixes bug 8059; bugfix on 0.2.0.10-alpha. Reported pseudonymously. - Make the format and order of STREAM events for DNS lookups consistent among the various ways to launch DNS lookups. Fixes bug 8203; bugfix on 0.2.0.24-rc. Patch by "Desoxy". o Minor bugfixes (syscalls and disk interaction): - Always check the return values of functions fcntl() and setsockopt(). We don't believe these are ever actually failing in practice, but better safe than sorry. Also, checking these return values should please analysis tools like Coverity. Patch from 'flupzor'. Fixes bug 8206; bugfix on all versions of Tor. - Avoid double-closing the listener socket in our socketpair() replacement (used on Windows) in the case where the addresses on our opened sockets don't match what we expected. Fixes bug 9400; bugfix on 0.0.2pre7. Found by Coverity. - Correctly store microdescriptors and extrainfo descriptors that include an internal NUL byte. Fixes bug 8037; bugfix on 0.2.0.1-alpha. Bug reported by "cypherpunks". - If for some reason we fail to write a microdescriptor while rebuilding the cache, do not let the annotations from that microdescriptor linger in the cache file, and do not let the microdescriptor stay recorded as present in its old location. Fixes bug 9047; bugfix on 0.2.2.6-alpha. - Use direct writes rather than stdio when building microdescriptor caches, in an attempt to mitigate bug 8031, or at least make it less common. o Minor fixes (config options): - Warn and fail if a server is configured not to advertise any ORPorts at all. (We need *something* to put in our descriptor, or we just won't work.) - Behave correctly when the user disables LearnCircuitBuildTimeout but doesn't tell us what they would like the timeout to be. Fixes bug 6304; bugfix on 0.2.2.14-alpha. - Rename the (internal-use-only) UsingTestingNetworkDefaults option to start with a triple-underscore so the controller won't touch it. Patch by Meejah. Fixes bug 3155. Bugfix on 0.2.2.23-alpha. - Rename the (testing-use-only) _UseFilteringSSLBufferevents option so it doesn't start with _. Fixes bug 3155. Bugfix on 0.2.3.1-alpha. - When autodetecting the number of CPUs, use the number of available CPUs in preference to the number of configured CPUs. Inform the user if this reduces the number of available CPUs. Fixes bug 8002; bugfix on 0.2.3.1-alpha. - Command-line option "--version" implies "--quiet". Fixes bug 6997. - Make it an error when you set EntryNodes but disable UseGuardNodes, since it will (surprisingly to some users) ignore EntryNodes. Fixes bug 8180; bugfix on 0.2.3.11-alpha. - Avoid overflows when the user sets MaxCircuitDirtiness to a ridiculously high value, by imposing a (ridiculously high) 30-day maximum on MaxCircuitDirtiness. o Minor bugfixes (control protocol): - Stop sending a stray "(null)" in some cases for the server status "EXTERNAL_ADDRESS" controller event. Resolves bug 8200; bugfix on 0.1.2.6-alpha. - The ADDRMAP command can no longer generate an ill-formed error code on a failed MAPADDRESS. It now says "internal" rather than an English sentence fragment with spaces in the middle. Bugfix on Tor 0.2.0.19-alpha. o Minor bugfixes (clients / edges): - When we receive a RELAY_END cell with the reason DONE, or with no reason, before receiving a RELAY_CONNECTED cell, report the SOCKS status as "connection refused". Previously we reported these cases as success but then immediately closed the connection. Fixes bug 7902; bugfix on 0.1.0.1-rc. Reported by "oftc_must_be_destroyed". - If the guard we choose first doesn't answer, we would try the second guard, but once we connected to the second guard we would abandon it and retry the first one, slowing down bootstrapping. The fix is to treat all our initially chosen guards as acceptable to use. Fixes bug 9946; bugfix on 0.1.1.11-alpha. - When choosing which stream on a formerly stalled circuit to wake first, make better use of the platform's weak RNG. Previously, we had been using the % ("modulo") operator to try to generate a 1/N chance of picking each stream, but this behaves badly with many platforms' choice of weak RNG. Fixes bug 7801; bugfix on 0.2.2.20-alpha. o Minor bugfixes (path bias detection): - If the state file's path bias counts are invalid (presumably from a buggy Tor prior to 0.2.4.10-alpha), make them correct. Also add additional checks and log messages to the scaling of Path Bias counts, in case there still are remaining issues with scaling. Should help resolve bug 8235. - Prevent rounding error in path bias counts when scaling them down, and use the correct scale factor default. Also demote some path bias related log messages down a level and make others less scary sounding. Fixes bug 6647. Bugfix on 0.2.3.17-beta. - Remove a source of rounding error during path bias count scaling; don't count cannibalized circuits as used for path bias until we actually try to use them; and fix a circuit_package_relay_cell() warning message about n_chan==NULL. Fixes bug 7802. - Paste the description for PathBias parameters from the man page into or.h, so the code documents them too. Fixes bug 7982; bugfix on 0.2.3.17-beta. o Minor bugfixes (relays): - Stop trying to resolve our hostname so often (e.g. every time we think about doing a directory fetch). Now we reuse the cached answer in some cases. Fixes bugs 1992 (bugfix on 0.2.0.20-rc) and 2410 (bugfix on 0.1.2.2-alpha). - When examining the list of network interfaces to find our address, do not consider non-running or disabled network interfaces. Fixes bug 9904; bugfix on 0.2.3.11-alpha. Patch from "hantwister". o Minor bugfixes (blocking resistance): - Only disable TLS session ticket support when running as a TLS server. Now clients will blend better with regular Firefox connections. Fixes bug 7189; bugfix on Tor 0.2.3.23-rc. o Minor bugfixes (IPv6): - Use square brackets around IPv6 addresses in numerous places that needed them, including log messages, HTTPS CONNECT proxy requests, TransportProxy statefile entries, and pluggable transport extra-info lines. Fixes bug 7011; patch by David Fifield. o Minor bugfixes (directory authorities): - Reject consensus votes with more than 64 known-flags. We aren't even close to that limit yet, and our code doesn't handle it correctly. Fixes bug 6833; bugfix on 0.2.0.1-alpha. - Correctly handle votes with more than 31 flags. Fixes bug 6853; bugfix on 0.2.0.3-alpha. o Minor bugfixes (memory leaks): - Avoid leaking memory if we fail to compute a consensus signature or we generate a consensus we can't parse. Bugfix on 0.2.0.5-alpha. - Fix a memory leak when receiving headers from an HTTPS proxy. Bugfix on 0.2.1.1-alpha; fixes bug 7816. - Fix a memory leak during safe-cookie controller authentication. Bugfix on 0.2.3.13-alpha; fixes bug 7816. - Free some more still-in-use memory at exit, to make hunting for memory leaks easier. Resolves bug 7029. o Minor bugfixes (code correctness): - Increase the width of the field used to remember a connection's link protocol version to two bytes. Harmless for now, since the only currently recognized versions are one byte long. Reported pseudonymously. Fixes bug 8062; bugfix on 0.2.0.10-alpha. - Fix a crash when debugging unit tests on Windows: deallocate a shared library with FreeLibrary, not CloseHandle. Fixes bug 7306; bugfix on 0.2.2.17-alpha. Reported by "ultramage". - When detecting the largest possible file descriptor (in order to close all file descriptors when launching a new program), actually use _SC_OPEN_MAX. The old code for doing this was very, very broken. Fixes bug 8209; bugfix on 0.2.3.1-alpha. Found by Coverity; this is CID 743383. - Avoid a crash if we fail to generate an extrainfo descriptor. Fixes bug 8208; bugfix on 0.2.3.16-alpha. Found by Coverity; this is CID 718634. - Avoid an off-by-one error when checking buffer boundaries when formatting the exit status of a pluggable transport helper. This is probably not an exploitable bug, but better safe than sorry. Fixes bug 9928; bugfix on 0.2.3.18-rc. Bug found by Pedro Ribeiro. - Get rid of a couple of harmless clang warnings, where we compared enums to ints. These warnings are newly introduced in clang 3.2. o Minor bugfixes (code cleanliness): - Avoid use of reserved identifiers in our C code. The C standard doesn't like us declaring anything that starts with an underscore, so let's knock it off before we get in trouble. Fix for bug 1031; bugfix on the first Tor commit. - Fix round_to_power_of_2() so it doesn't invoke undefined behavior with large values. This situation was untriggered, but nevertheless incorrect. Fixes bug 6831; bugfix on 0.2.0.1-alpha. - Fix an impossible buffer overrun in the AES unit tests. Fixes bug 8845; bugfix on 0.2.0.7-alpha. Found by eugenis. - Fix handling of rendezvous client authorization types over 8. Fixes bug 6861; bugfix on 0.2.1.5-alpha. - Remove a couple of extraneous semicolons that were upsetting the cparser library. Patch by Christian Grothoff. Fixes bug 7115; bugfix on 0.2.2.1-alpha. - When complaining about a client port on a public address, log which address we're complaining about. Fixes bug 4020; bugfix on 0.2.3.3-alpha. Patch by Tom Fitzhenry. o Minor bugfixes (log messages, warnings): - If we encounter a write failure on a SOCKS connection before we finish our SOCKS handshake, don't warn that we closed the connection before we could send a SOCKS reply. Fixes bug 8427; bugfix on 0.1.0.1-rc. - Fix a directory authority warn caused when we have a large amount of badexit bandwidth. Fixes bug 8419; bugfix on 0.2.2.10-alpha. - Downgrade "Failed to hand off onionskin" messages to "debug" severity, since they're typically redundant with the "Your computer is too slow" messages. Fixes bug 7038; bugfix on 0.2.2.16-alpha. - Avoid spurious warnings when configuring multiple client ports of which only some are nonlocal. Previously, we had claimed that some were nonlocal when in fact they weren't. Fixes bug 7836; bugfix on 0.2.3.3-alpha. o Minor bugfixes (log messages, other): - Fix log messages and comments to avoid saying "GMT" when we mean "UTC". Fixes bug 6113. - When rejecting a configuration because we were unable to parse a quoted string, log an actual error message. Fixes bug 7950; bugfix on 0.2.0.16-alpha. - Correctly recognize that [::1] is a loopback address. Fixes bug 8377; bugfix on 0.2.1.3-alpha. - Don't log inappropriate heartbeat messages when hibernating: a hibernating node is _expected_ to drop out of the consensus, decide it isn't bootstrapped, and so forth. Fixes bug 7302; bugfix on 0.2.3.1-alpha. - Eliminate several instances where we use "Nickname=ID" to refer to nodes in logs. Use "Nickname (ID)" instead. (Elsewhere, we still use "$ID=Nickname", which is also acceptable.) Fixes bug 7065. Bugfix on 0.2.3.21-rc. o Minor bugfixes (build): - Fix some bugs in tor-fw-helper-natpmp when trying to build and run it on Windows. More bugs likely remain. Patch from Gisle Vanem. Fixes bug 7280; bugfix on 0.2.3.1-alpha. o Documentation fixes: - Make the torify manpage no longer refer to tsocks; torify hasn't supported tsocks since 0.2.3.14-alpha. - Make the tor manpage no longer reference tsocks. - Fix the GeoIPExcludeUnknown documentation to refer to ExcludeExitNodes rather than the currently nonexistent ExcludeEntryNodes. Spotted by "hamahangi" on tor-talk. - Resolve a typo in torrc.sample.in. Fixes bug 6819; bugfix on 0.2.3.14-alpha. - Say "KBytes" rather than "KB" in the man page (for various values of K), to further reduce confusion about whether Tor counts in units of memory or fractions of units of memory. Resolves ticket 7054. - Update tor-fw-helper.1.txt and tor-fw-helper.c to make option names match. Fixes bug 7768. - Fix the documentation of HeartbeatPeriod to say that the heartbeat message is logged at notice, not at info. - Clarify the usage and risks of setting the ContactInfo torrc line for your relay or bridge. Resolves ticket 9854. - Add anchors to the manpage so we can link to the html version of the documentation for specific options. Resolves ticket 9866. - Replace remaining references to DirServer in man page and log entries. Resolves ticket 10124. o Removed features: - Stop exporting estimates of v2 and v3 directory traffic shares in extrainfo documents. They were unneeded and sometimes inaccurate. Also stop exporting any v2 directory request statistics. Resolves ticket 5823. - Drop support for detecting and warning about versions of Libevent before 1.3e. Nothing reasonable ships with them any longer; warning the user about them shouldn't be needed. Resolves ticket 6826. - Now that all versions before 0.2.2.x are disallowed, we no longer need to work around their missing features. Remove a bunch of compatibility code. o Removed files: - The tor-tsocks.conf is no longer distributed or installed. We recommend that tsocks users use torsocks instead. Resolves ticket 8290. - Remove some of the older contents of doc/ as obsolete; move others to torspec.git. Fixes bug 8965. o Code simplification: - Avoid using character buffers when constructing most directory objects: this approach was unwieldy and error-prone. Instead, build smartlists of strings, and concatenate them when done. - Rename "isin" functions to "contains", for grammar. Resolves ticket 5285. - Rename Tor's logging function log() to tor_log(), to avoid conflicts with the natural logarithm function from the system libm. Resolves ticket 7599. - Start using OpenBSD's implementation of queue.h, so that we don't need to hand-roll our own pointer and list structures whenever we need them. (We can't rely on a sys/queue.h, since some operating systems don't have them, and the ones that do have them don't all present the same extensions.) - Start using OpenBSD's implementation of queue.h (originally by Niels Provos). - Enhance our internal sscanf replacement so that we can eliminate the last remaining uses of the system sscanf. (Though those uses of sscanf were safe, sscanf itself is generally error prone, so we want to eliminate when we can.) Fixes ticket 4195 and Coverity CID 448. - Replace all calls to snprintf() outside of src/ext with tor_snprintf(). Also remove the #define to replace snprintf with _snprintf on Windows; they have different semantics, and all of our callers should be using tor_snprintf() anyway. Fixes bug 7304. o Refactoring: - Add a wrapper function for the common "log a message with a rate-limit" case. - Split the onion.c file into separate modules for the onion queue and the different handshakes it supports. - Move the client-side address-map/virtual-address/DNS-cache code out of connection_edge.c into a new addressmap.c module. - Move the entry node code from circuitbuild.c to its own file. - Move the circuit build timeout tracking code from circuitbuild.c to its own file. - Source files taken from other packages now reside in src/ext; previously they were scattered around the rest of Tor. - Move the generic "config" code into a new file, and have "config.c" hold only torrc- and state-related code. Resolves ticket 6823. - Move the core of our "choose a weighted element at random" logic into its own function, and give it unit tests. Now the logic is testable, and a little less fragile too. - Move ipv6_preferred from routerinfo_t to node_t. Addresses bug 4620. - Move last_reachable and testing_since from routerinfo_t to node_t. Implements ticket 5529. - Add replaycache_t structure, functions and unit tests, then refactor rend_service_introduce() to be more clear to read, improve, debug, and test. Resolves bug 6177. o Removed code: - Remove some now-needless code that tried to aggressively flush OR connections as data was added to them. Since 0.2.0.1-alpha, our cell queue logic has saved us from the failure mode that this code was supposed to prevent. Removing this code will limit the number of baroque control flow paths through Tor's network logic. Reported pseudonymously on IRC. Fixes bug 6468; bugfix on 0.2.0.1-alpha. - Remove unused code for parsing v1 directories and "running routers" documents. Fixes bug 6887. - Remove the marshalling/unmarshalling code for sending requests to cpuworkers over a socket, and instead just send structs. The recipient will always be the same Tor binary as the sender, so any encoding is overkill. - Remove the testing_since field of node_t, which hasn't been used for anything since 0.2.0.9-alpha. - Finally remove support for malloc_good_size and malloc_usable_size. We had hoped that these functions would let us eke a little more memory out of our malloc implementation. Unfortunately, the only implementations that provided these functions are also ones that are already efficient about not overallocation: they never got us more than 7 or so bytes per allocation. Removing them saves us a little code complexity and a nontrivial amount of build complexity.

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Tor security advisory: Old Tor Browser Bundles vulnerable
by Roger Dingledine 05 Aug '13

05 Aug '13

SUMMARY: This is a critical security announcement. An attack that exploits a Firefox vulnerability in JavaScript [1] has been observed in the wild. Specifically, Windows users using the Tor Browser Bundle (which includes Firefox plus privacy patches [2]) appear to have been targeted. This vulnerability was fixed in Firefox 17.0.7 ESR [3]. The following versions of the Tor Browser Bundle include this fixed version: 2.3.25-10 (released June 26 2013) [4] 2.4.15-alpha-1 (released June 26 2013) [4] 2.4.15-beta-1 (released July 8 2013) [5] 3.0alpha2 (released June 30 2013) [6] Tor Browser Bundle users should ensure they're running a recent enough bundle version, and consider taking further security precautions as described below. WHO IS AFFECTED: In principle, all users of all Tor Browser Bundles earlier than the above versions are vulnerable. But in practice, it appears that only Windows users with vulnerable Firefox versions were actually exploitable by this attack. (If you're not sure what version you have, click on "Help -> About Torbrowser" and make sure it says Firefox 17.0.7. Here's a video: [7]) To be clear, while the Firefox vulnerability is cross-platform, the attack code is Windows-specific. It appears that TBB users on Linux and OS X, as well as users of LiveCD systems like Tails, were not exploited by this attack. IMPACT: The vulnerability allows arbitrary code execution, so an attacker could in principle take over the victim's computer. However, the observed version of the attack appears to collect the hostname and MAC address of the victim computer, send that to a remote webserver over a non-Tor connection, and then crash or exit [8]. The attack appears to have been injected into (or by) various Tor hidden services [9], and it's reasonable to conclude that the attacker now has a list of vulnerable Tor users who visited those hidden services. We don't currently believe that the attack modifies anything on the victim computer. WHAT TO DO: First, be sure you're running a recent enough Tor Browser Bundle. That should keep you safe from this attack. Second, be sure to keep up-to-date in the future. Tor Browser Bundle automatically checks whether it's out of date, and notifies you on its homepage when you need to upgrade. Recent versions also add a flashing exclamation point over the Tor onion icon. We also post about new versions on the Tor blog: https://blog.torproject.org/ Third, realize that this wasn't the first Firefox vulnerability, nor will it be the last [10]. Consider disabling JavaScript (click the blue "S" beside the green onion, and select "Forbid Scripts Globally"). Disabling JavaScript will reduce your vulnerability to other attacks like this one, but disabling JavaScript will make some websites not work like you expect. A future version of Tor Browser Bundle will have an easier interface for letting you configure your JavaScript settings [11]. You might also like Request Policy [12]. And you might want to randomize your MAC address, install various firewalls, etc. Fourth, consider switching to a "live system" approach like Tails [13]. Really, switching away from Windows is probably a good security move for many reasons. And finally, be aware that many other vectors remain for vulnerabilities in Firefox. JavaScript is one big vector for attack, but many other big vectors exist, like css, svg, xml, the renderer, etc. We need help improving usability of (and doing more security analysis of) better sandboxing approaches [14] as well as VM-based approaches like Whonix [15] and WiNoN [16]. Please help! [1] https://www.mozilla.org/security/announce/2013/mfsa2013-53.html [2] https://www.torproject.org/projects/torbrowser/design/ [3] https://blog.mozilla.org/security/2013/08/04/investigating-security-vulnera… [4] https://blog.torproject.org/blog/new-tor-browser-bundles-and-tor-02414-alph… [5] https://blog.torproject.org/blog/tor-02415-rc-packages-available [6] https://blog.torproject.org/blog/tor-browser-bundle-30alpha2-released [7] https://media.torproject.org/video/2013-08-05-TBBversion.mp4 [8] http://tsyrklevich.net/tbb_payload.txt [9] https://blog.torproject.org/blog/hidden-services-current-events-and-freedom… [10] https://www.mozilla.org/security/known-vulnerabilities/firefoxESR.html [11] https://trac.torproject.org/projects/tor/ticket/9387 [12] https://www.requestpolicy.com/ [13] https://tails.boum.org/ [14] https://trac.torproject.org/projects/tor/ticket/7680 [15] http://sourceforge.net/projects/whonix/ [16] http://dedis.cs.yale.edu/2010/anon/papers/osdi12.pdf https://trac.torproject.org/projects/tor/ticket/7681

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Tor 0.2.3.25 is released
by Roger Dingledine 01 Mar '13

01 Mar '13

The Tor 0.2.3 release series is dedicated to the memory of Len "rabbi" Sassaman (1980-2011), a long-time cypherpunk, anonymity researcher, Mixmaster maintainer, Pynchon Gate co-designer, CodeCon organizer, programmer, and friend. Unstinting in his dedication to the cause of freedom, he inspired and helped many of us as we began our work on anonymity, and inspires us still. Please honor his memory by writing software to protect people's freedoms, and by helping others to do so. Tor 0.2.3.25, the first stable release in the 0.2.3 branch, features significantly reduced directory overhead (via microdescriptors), enormous crypto performance improvements for fast relays on new enough hardware, a new v3 TLS handshake protocol that can better resist fingerprinting, support for protocol obfuscation plugins (aka pluggable transports), better scalability for hidden services, IPv6 support for bridges, performance improvements like allowing clients to skip the first round-trip on the circuit ("optimistic data") and refilling token buckets more often, a new "stream isolation" design to isolate different applications on different circuits, and many stability, security, and privacy fixes. (I apologize for the delay in announcing the release to this list: I was waiting for the Tor Browser Bundles with it to stabilize a bit, but with the new integration to Firefox 17, it's become clear that TBB will be in flux a while more.) https://www.torproject.org/download/download Changes in version 0.2.3.25 - 2012-11-19 Major features (v3 directory protocol): - Clients now use microdescriptors instead of regular descriptors to build circuits. Microdescriptors are authority-generated summaries of regular descriptors' contents, designed to change very rarely (see proposal 158 for details). This feature is designed to save bandwidth, especially for clients on slow internet connections. Use "UseMicrodescriptors 0" to disable it. - Caches now download, cache, and serve microdescriptors, as well as multiple "flavors" of the consensus, including a flavor that describes microdescriptors. o Major features (build hardening): - Enable gcc and ld hardening by default. Resolves ticket 5210. o Major features (relay scaling): - When built to use OpenSSL 1.0.1, and built for an x86 or x86_64 instruction set, take advantage of OpenSSL's AESNI, bitsliced, or vectorized AES implementations as appropriate. These can be much, much faster than other AES implementations. - When using OpenSSL 1.0.0 or later, use OpenSSL's counter mode implementation. It makes AES_CTR about 7% faster than our old one (which was about 10% faster than the one OpenSSL used to provide). Resolves ticket 4526. - Use OpenSSL's EVP interface for AES encryption, so that all AES operations can use hardware acceleration (if present). Resolves ticket 4442. - Unconditionally use OpenSSL's AES implementation instead of our old built-in one. OpenSSL's AES has been better for a while, and relatively few servers should still be on any version of OpenSSL that doesn't have good optimized assembly AES. o Major features (blocking resistance): - Update TLS cipher list to match Firefox 8 and later. Resolves ticket 4744. - Remove support for clients falsely claiming to support standard ciphersuites that they can actually provide. As of modern OpenSSL versions, it's not necessary to fake any standard ciphersuite, and doing so prevents us from using better ciphersuites in the future, since servers can't know whether an advertised ciphersuite is really supported or not. Some hosts -- notably, ones with very old versions of OpenSSL or where OpenSSL has been built with ECC disabled -- will stand out because of this change; TBB users should not be affected. Implements the client side of proposal 198. - Implement a new handshake protocol (v3) for authenticating Tors to each other over TLS. It should be more resistant to fingerprinting than previous protocols, and should require less TLS hacking for future Tor implementations. Implements proposal 176. - Allow variable-length padding cells, to disguise the length of Tor's TLS records. Implements part of proposal 184. - While we're trying to bootstrap, record how many TLS connections fail in each state, and report which states saw the most failures in response to any bootstrap failures. This feature may speed up diagnosis of censorship events. Implements ticket 3116. o Major features (pluggable transports): - Clients and bridges can now be configured to use a separate "transport" proxy. This approach makes the censorship arms race easier by allowing bridges to use protocol obfuscation plugins. Implements proposal 180 (tickets 2841 and 3472). o Major features (DoS resistance): - Now that Tor 0.2.0.x is completely deprecated, enable the final part of "Proposal 110: Avoiding infinite length circuits" by refusing all circuit-extend requests that do not use a relay_early cell. This change helps Tor resist a class of denial-of-service attacks by limiting the maximum circuit length. - Tear down the circuit if we get an unexpected SENDME cell. Clients could use this trick to make their circuits receive cells faster than our flow control would have allowed, or to gum up the network, or possibly to do targeted memory denial-of-service attacks on entry nodes. Fixes bug 6252. Bugfix on the 54th commit on Tor -- from July 2002, before the release of Tor 0.0.0. o Major features (hidden services): - Adjust the number of introduction points that a hidden service will try to maintain based on how long its introduction points remain in use and how many introductions they handle. Fixes part of bug 3825. - Add a "tor2web mode" for clients that want to connect to hidden services non-anonymously (and possibly more quickly). As a safety measure to try to keep users from turning this on without knowing what they are doing, tor2web mode must be explicitly enabled at compile time, and a copy of Tor compiled to run in tor2web mode cannot be used as a normal Tor client. Implements feature 2553. o Major features (IPv6): - Clients can now connect to private bridges over IPv6. Bridges still need at least one IPv4 address in order to connect to other relays. Note that we don't yet handle the case where the user has two bridge lines for the same bridge (one IPv4, one IPv6). Implements parts of proposal 186. o Major features (directory authorities): - Use a more secure consensus parameter voting algorithm. Now at least three directory authorities or a majority of them must vote on a given parameter before it will be included in the consensus. Implements proposal 178. - Remove the artificially low cutoff of 20KB to guarantee the Fast flag. In the past few years the average relay speed has picked up, and while the "top 7/8 of the network get the Fast flag" and "all relays with 20KB or more of capacity get the Fast flag" rules used to have the same result, now the top 7/8 of the network has a capacity more like 32KB. Bugfix on 0.2.1.14-rc. Fixes bug 4489. o Major features (performance): - Exit nodes now accept and queue data on not-yet-connected streams. Previously, the client wasn't allowed to send data until the stream was connected, which slowed down all connections. This change will enable clients to perform a "fast-start" on streams and send data without having to wait for a confirmation that the stream has opened. Patch from Ian Goldberg; implements the server side of Proposal 174. - When using an exit relay running 0.2.3.x, clients can now "optimistically" send data before the exit relay reports that the stream has opened. This saves a round trip when starting connections where the client speaks first (such as web browsing). This behavior is controlled by a consensus parameter (currently disabled). To turn it on or off manually, use the "OptimisticData" torrc option. Implements proposal 181; code by Ian Goldberg. - Add a new TokenBucketRefillInterval option to refill token buckets more frequently than once per second. This should improve network performance, alleviate queueing problems, and make traffic less bursty. Implements proposal 183; closes ticket 3630. Design by Florian Tschorsch and BjÃ¶rn Scheuermann; implementation by Florian Tschorsch. - Raise the threshold of server descriptors needed (75%) and exit server descriptors needed (50%) before we will declare ourselves bootstrapped. This will make clients start building circuits a little later, but makes the initially constructed circuits less skewed and less in conflict with further directory fetches. Fixes ticket 3196. o Major features (relays): - Relays now try regenerating and uploading their descriptor more frequently if they are not listed in the consensus, or if the version of their descriptor listed in the consensus is too old. This fix should prevent situations where a server declines to re-publish itself because it has done so too recently, even though the authorities decided not to list its recent-enough descriptor. Fix for bug 3327. o Major features (stream isolation): - You can now configure Tor so that streams from different applications are isolated on different circuits, to prevent an attacker who sees your streams as they leave an exit node from linking your sessions to one another. To do this, choose some way to distinguish the applications: have them connect to different SocksPorts, or have one of them use SOCKS4 while the other uses SOCKS5, or have them pass different authentication strings to the SOCKS proxy. Then, use the new SocksPort syntax to configure the degree of isolation you need. This implements Proposal 171. - There's a new syntax for specifying multiple client ports (such as SOCKSPort, TransPort, DNSPort, NATDPort): you can now just declare multiple *Port entries with full addr:port syntax on each. The old *ListenAddress format is still supported, but you can't mix it with the new *Port syntax. o Major features (bufferevents): - Tor can now optionally build with the "bufferevents" buffered IO backend provided by Libevent 2. To use this feature, make sure you have the latest possible version of Libevent, and pass the --enable-bufferevents flag to configure when building Tor from source. This feature will make our networking code more flexible, let us stack layers on each other, and let us use more efficient zero-copy transports where available. - Add experimental support for running on Windows with IOCP and no kernel-space socket buffers. This feature is controlled by a new "UserspaceIOCPBuffers" config option (off by default), which has no effect unless Tor has been built with bufferevents enabled, you're running on Windows, and you've set "DisableIOCP 0". In the long run, this may help solve or mitigate bug 98. o Major features (path selection): - The EntryNodes option can now include country codes like {de} or IP addresses or network masks. Previously we had disallowed these options because we didn't have an efficient way to keep the list up to date. Addresses ticket 1982, but see bug 2798 for an unresolved issue here. o Major features (port forwarding): - Add support for automatic port mapping on the many home routers that support NAT-PMP or UPnP. To build the support code, you'll need to have the libnatpnp library and/or the libminiupnpc library, and you'll need to enable the feature specifically by passing "--enable-upnp" and/or "--enable-natpnp" to ./configure. To turn it on, use the new PortForwarding option. o Major features (logging): - Add a new 'Heartbeat' log message type to periodically log a message describing Tor's status at level Notice. This feature is meant for operators who log at notice, and want to make sure that their Tor server is still working. Implementation by George Kadianakis. - Make logging resolution configurable with a new LogTimeGranularity option, and change the default from 1 millisecond to 1 second. Implements enhancement 1668. o Major features (other): - New "DisableNetwork" config option to prevent Tor from launching any connections or accepting any connections except on a control port. Bundles and controllers can set this option before letting Tor talk to the rest of the network, for example to prevent any connections to a non-bridge address. Packages like Orbot can also use this option to instruct Tor to save power when the network is off. - Try to use system facilities for enumerating local interface addresses, before falling back to our old approach (which was binding a UDP socket, and calling getsockname() on it). That approach was scaring OS X users whose draconian firewall software warned about binding to UDP sockets regardless of whether packets were sent. Now we try to use getifaddrs(), SIOCGIFCONF, or GetAdaptersAddresses(), depending on what the system supports. Resolves ticket 1827. - Add experimental support for a "defaults" torrc file to be parsed before the regular torrc. Torrc options override the defaults file's options in the same way that the command line overrides the torrc. The SAVECONF controller command saves only those options which differ between the current configuration and the defaults file. HUP reloads both files. Implements task 4552. o New directory authorities: - Add Faravahar (run by Sina Rabbani) as the ninth v3 directory authority. Closes ticket 5749. o Security/privacy fixes: - Avoid read-from-freed-memory and double-free bugs that could occur when a DNS request fails while launching it. Fixes bug 6480; bugfix on 0.2.0.1-alpha. - Reject any attempt to extend to an internal address. Without this fix, a router could be used to probe addresses on an internal network to see whether they were accepting connections. Fixes bug 6710; bugfix on 0.0.8pre1. - Close any connection that sends unrecognized junk before the TLS handshake. Solves an issue noted in bug 4369. - The advertised platform of a relay now includes only its operating system's name (e.g., "Linux", "Darwin", "Windows 7"), and not its service pack level (for Windows) or its CPU architecture (for Unix). Also drop the "git-XYZ" tag in the version. Packagers can insert an extra string in the platform line by setting the preprocessor variable TOR_BUILD_TAG. Resolves bug 2988. - Disable TLS session tickets. OpenSSL's implementation was giving our TLS session keys the lifetime of our TLS context objects, when perfect forward secrecy would want us to discard anything that could decrypt a link connection as soon as the link connection was closed. Fixes bug 7139; bugfix on all versions of Tor linked against OpenSSL 1.0.0 or later. Found by Florent DaigniÃ¨re. - Tor tries to wipe potentially sensitive data after using it, so that if some subsequent security failure exposes Tor's memory, the damage will be limited. But we had a bug where the compiler was eliminating these wipe operations when it decided that the memory was no longer visible to a (correctly running) program, hence defeating our attempt at defense in depth. We fix that by using OpenSSL's OPENSSL_cleanse() operation, which a compiler is unlikely to optimize away. Future versions of Tor may use a less ridiculously heavy approach for this. Fixes bug 7352. Reported in an article by Andrey Karpov. o Major bugfixes (crashes and asserts): - Avoid a pair of double-free and use-after-mark bugs that can occur with certain timings in canceled and re-received DNS requests. Fixes bug 6472; bugfix on 0.0.7rc1. - Fix a denial of service attack by which any directory authority could crash all the others, or by which a single v2 directory authority could crash everybody downloading v2 directory information. Fixes bug 7191; bugfix on 0.2.0.10-alpha. - Fix an assert that directory authorities could trigger on sighup during some configuration state transitions. We now don't treat it as a fatal error when the new descriptor we just generated in init_keys() isn't accepted. Fixes bug 4438; bugfix on 0.2.1.9-alpha. - Avoid segfault when starting up having run with an extremely old version of Tor and parsing its state file. Fixes bug 6801; bugfix on 0.2.2.23-alpha. o Major bugfixes (clients): - If we are unable to find any exit that supports our predicted ports, stop calling them predicted, so that we don't loop and build hopeless circuits indefinitely. Fixes bug 3296; bugfix on 0.0.9pre6, which introduced predicted ports. - Check at each new consensus whether our entry guards were picked long enough ago that we should rotate them. Previously, we only did this check at startup, which could lead to us holding a guard indefinitely. Fixes bug 5380; bugfix on 0.2.1.14-rc. - When fetching a bridge descriptor from a bridge authority, always do so anonymously, whether we have been able to open circuits or not. Partial fix for bug 1938; bugfix on 0.2.0.7-alpha. This behavior makes it *safer* to use UpdateBridgesFromAuthority, but we'll need to wait for bug 6010 before it's actually usable. o Major bugfixes (directory voting): - Check more thoroughly to prevent a rogue authority from double-voting on any consensus directory parameter. Previously, authorities would crash in this case if the total number of votes for any parameter exceeded the number of active voters, but would let it pass otherwise. Partially fixes bug 5786; bugfix on 0.2.2.2-alpha. - When computing weight parameters, behave more robustly in the presence of a bad bwweightscale value. Previously, the authorities would crash if they agreed on a sufficiently broken weight_scale value; now, they use a reasonable default and carry on. Fixes the rest of bug 5786; bugfix on 0.2.2.17-alpha. - If authorities are unable to get a v2 consensus document from other directory authorities, they no longer fall back to fetching them from regular directory caches. Fixes bug 5635; bugfix on 0.2.2.26-beta, where routers stopped downloading v2 consensus documents entirely. o Major bugfixes (relays): - Fix a bug handling SENDME cells on nonexistent streams that could result in bizarre window values. Report and patch contributed pseudonymously. Fixes part of bug 6271. This bug was introduced before the first Tor release, in svn commit r152. - Don't update the AccountingSoftLimitHitAt state file entry whenever tor gets started. This prevents a wrong average bandwidth estimate, which would cause relays to always start a new accounting interval at the earliest possible moment. Fixes bug 2003; bugfix on 0.2.2.7-alpha. Reported by Bryon Eldridge, who also helped immensely in tracking this bug down. - Fix a possible crash bug when checking for deactivated circuits in connection_or_flush_from_first_active_circuit(). Fixes bug 6341; bugfix on 0.2.2.7-alpha. Bug report and fix received pseudonymously. - Set the SO_REUSEADDR socket option before we call bind() on outgoing connections. This change should allow busy exit relays to stop running out of available sockets as quickly. Fixes bug 4950; bugfix on 0.2.2.26-beta. o Major bugfixes (blocking resistance): - Bridges no longer include their address in NETINFO cells on outgoing OR connections, to allow them to blend in better with clients. Removes another avenue for enumerating bridges. Reported by "troll_un". Fixes bug 4348; bugfix on 0.2.0.10-alpha, when NETINFO cells were introduced. - Warn the user when HTTPProxy, but no other proxy type, is configured. This can cause surprising behavior: it doesn't send all of Tor's traffic over the HTTPProxy -- it sends unencrypted directory traffic only. Resolves ticket 4663. o Major bugfixes (hidden services): - Improve hidden service robustness: when an attempt to connect to a hidden service ends, be willing to refetch its hidden service descriptors from each of the HSDir relays responsible for them immediately. Previously, we would not consider refetching the service's descriptors from each HSDir for 15 minutes after the last fetch, which was inconvenient if the hidden service was not running during the first attempt. Bugfix on 0.2.0.18-alpha; fixes bug 3335. - Hidden services now ignore the timestamps on INTRODUCE2 cells. They used to check that the timestamp was within 30 minutes of their system clock, so they could cap the size of their replay-detection cache, but that approach unnecessarily refused service to clients with wrong clocks. Bugfix on 0.2.1.6-alpha, when the v3 intro-point protocol (the first one which sent a timestamp field in the INTRODUCE2 cell) was introduced; fixes bug 3460. - When one of a hidden service's introduction points appears to be unreachable, stop trying it. Previously, we would keep trying to build circuits to the introduction point until we lost the descriptor, usually because the user gave up and restarted Tor. Fixes part of bug 3825. o Changes to default torrc file: - Stop listing "socksport 9050" in torrc.sample. We open a socks port on 9050 by default anyway, so this should not change anything in practice. - Stop mentioning the deprecated *ListenAddress options in torrc.sample. Fixes bug 5438. - Document unit of bandwidth-related options in sample torrc. Fixes bug 5621. - Fix broken URLs in the sample torrc file, and tell readers about the OutboundBindAddress, ExitPolicyRejectPrivate, and PublishServerDescriptor options. Addresses bug 4652. o Minor features (directory authorities): - Consider new, removed or changed IPv6 OR ports a non-cosmetic change when the authority is deciding whether to accept a newly uploaded descriptor. Implements ticket 6423. - Directory authorities are now a little more lenient at accepting older router descriptors, or newer router descriptors that don't make big changes. This should help ameliorate past and future issues where routers think they have uploaded valid descriptors, but the authorities don't think so. Fix for ticket 2479. - Authority operators can now vote for all relays in a given set of countries to be BadDir/BadExit/Invalid/Rejected. - Provide two consensus parameters (FastFlagMinThreshold and FastFlagMaxThreshold) to control the range of allowable bandwidths for the Fast directory flag. These allow authorities to run experiments on appropriate requirements for being a "Fast" node. The AuthDirFastGuarantee config value still applies. Implements ticket 3946. o Minor features (bridges / bridge authorities): - Make bridge SSL certificates a bit more stealthy by using random serial numbers, in the same fashion as OpenSSL when generating self-signed certificates. Implements ticket 4584. - Tag a bridge's descriptor as "never to be sent unencrypted". This shouldn't matter, since bridges don't open non-anonymous connections to the bridge authority and don't allow unencrypted directory connections from clients, but we might as well make sure. Closes bug 5139. - The Bridge Authority now writes statistics on how many bridge descriptors it gave out in total, and how many unique descriptors it gave out. It also lists how often the most and least commonly fetched descriptors were given out, as well as the median and 25th/75th percentile. Implements tickets 4200 and 4294. o Minor features (IPv6): - Make the code that clients use to detect an address change be IPv6-aware, so that it won't fill clients' logs with error messages when trying to get the IPv4 address of an IPv6 connection. Implements ticket 5537. - Relays now understand an IPv6 address when they get one from a directory server. Resolves ticket 4875. o Minor features (hidden services): - Expire old or over-used hidden service introduction points. Required by fix for bug 3460. - Reduce the lifetime of elements of hidden services' Diffie-Hellman public key replay-detection cache from 60 minutes to 5 minutes. This replay-detection cache is now used only to detect multiple INTRODUCE2 cells specifying the same rendezvous point, so we can avoid launching multiple simultaneous attempts to connect to it. - When a hidden service's introduction point times out, consider trying it again during the next attempt to connect to the HS. Previously, we would not try it again unless a newly fetched descriptor contained it. Required by fixes for bugs 1297 and 3825. o Minor features (relays): - Relays now include a reason for regenerating their descriptors in an HTTP header when uploading to the authorities. This will make it easier to debug descriptor-upload issues in the future. - Turn on directory request statistics by default and include them in extra-info descriptors. Don't break if we have no GeoIP database. - Replace files in stats/ rather than appending to them. Now that we include statistics in extra-info descriptors, it makes no sense to keep old statistics forever. Implements ticket 2930. - Relays that set "ConnDirectionStatistics 1" write statistics on the bidirectional use of connections to disk every 24 hours. - Add a GeoIP file digest to the extra-info descriptor. Implements ticket 1883. o Minor features (new config options): - New config option "DynamicDHGroups" (disabled by default) provides each bridge with a unique prime DH modulus to be used during SSL handshakes. This option attempts to help against censors who might use the Apache DH modulus as a static identifier for bridges. Addresses ticket 4548. - New config option "DisableDebuggerAttachment" (on by default) to prevent basic debugging attachment attempts by other processes. Supports Mac OS X and Gnu/Linux. Resolves ticket 3313. - Ordinarily, Tor does not count traffic from private addresses (like 127.0.0.1 or 10.0.0.1) when calculating rate limits or accounting. There is now a new option, CountPrivateBandwidth, to disable this behavior. Patch from Daniel Cagara. o Minor features (different behavior for old config options): - Allow MapAddress directives to specify matches against super-domains, as in "MapAddress *.torproject.org *.torproject.org.torserver.exit". Implements issue 933. - Don't disable the DirPort when we cannot exceed our AccountingMax limit during this interval because the effective bandwidthrate is low enough. This is useful in a situation where AccountMax is only used as an additional safeguard or to provide statistics. - Add port 6523 (Gobby) to LongLivedPorts. Patch by intrigeri; implements ticket 3439. - When configuring a large set of nodes in EntryNodes, and there are enough of them listed as Guard so that we don't need to consider the non-guard entries, prefer the ones listed with the Guard flag. - If you set the NumCPUs option to 0, Tor will now try to detect how many CPUs you have. This is the new default behavior. - The NodeFamily option -- which let you declare that you want to consider nodes to be part of a family whether they list themselves that way or not -- now allows IP address ranges and country codes. o Minor features (new command-line config behavior): - Slightly change behavior of "list" options (that is, config options that can appear more than once) when they appear both in torrc and on the command line. Previously, the command-line options would be appended to the ones from torrc. Now, the command-line options override the torrc options entirely. This new behavior allows the user to override list options (like exit policies and ports to listen on) from the command line, rather than simply appending to the list. - You can get the old (appending) command-line behavior for "list" options by prefixing the option name with a "+". - You can remove all the values for a "list" option from the command line without adding any new ones by prefixing the option name with a "/". o Minor features (controller, new events): - Extend the control protocol to report flags that control a circuit's path selection in CIRC events and in replies to 'GETINFO circuit-status'. Implements part of ticket 2411. - Extend the control protocol to report the hidden service address and current state of a hidden-service-related circuit in CIRC events and in replies to 'GETINFO circuit-status'. Implements part of ticket 2411. - Include the creation time of a circuit in CIRC and CIRC2 control-port events and the list produced by the 'GETINFO circuit-status' control-port command. - Add a new CONF_CHANGED event so that controllers can be notified of any configuration changes made by other controllers, or by the user. Implements ticket 1692. - Add a new SIGNAL event to the controller interface so that controllers can be notified when Tor handles a signal. Resolves issue 1955. Patch by John Brooks. o Minor features (controller, new getinfo options): - Expose our view of whether we have gone dormant to the controller, via a new "GETINFO dormant" value. Torbutton and other controllers can use this to avoid doing periodic requests through Tor while it's dormant (bug 4718). Resolves ticket 5954. - Add a new GETINFO option to get total bytes read and written. Patch from pipe, revised by atagar. Resolves ticket 2345. - Implement new GETINFO controller fields to provide information about the Tor process's pid, euid, username, and resource limits. o Minor features (controller, other): - Allow controllers to request an event notification whenever a circuit is cannibalized or its purpose is changed. Implements part of ticket 3457. - Use absolute path names when reporting the torrc filename in the control protocol, so a controller can more easily find the torrc file. Resolves bug 1101. - When reporting the path to the cookie file to the controller, give an absolute path. Resolves ticket 4881. o Minor features (log messages): - Add more information to a log statement that might help track down bug 4091. If you're seeing "Bug: tor_addr_is_internal() called with a non-IP address" messages (or any Bug messages, for that matter!), please let us know about it. - If EntryNodes are given, but UseEntryGuards is set to 0, warn that EntryNodes will have no effect. Resolves issue 2571. - Try to make the introductory warning message that Tor prints on startup more useful for actually finding help and information. Resolves ticket 2474. - When the system call to create a listener socket fails, log the error message explaining why. This may help diagnose bug 4027. o Minor features (other): - When we fail to initialize Libevent, retry with IOCP disabled so we don't need to turn on multi-threading support in Libevent, which in turn requires a working socketpair(). This is a workaround for bug 4457, which affects Libevent versions from 2.0.1-alpha through 2.0.15-stable. - When starting as root and then changing our UID via the User control option, and we have a ControlSocket configured, make sure that the ControlSocket is owned by the same account that Tor will run under. Implements ticket 3421; fix by JÃ©rÃ©my Bobbio. - Accept attempts to include a password authenticator in the handshake, as supported by SOCKS5. This handles SOCKS clients that don't know how to omit a password when authenticating. Resolves bug 1666. - Check for and recover from inconsistency in the microdescriptor cache. This will make it harder for us to accidentally free a microdescriptor without removing it from the appropriate data structures. Fixes issue 3135; issue noted by "wanoskarnet". - Shorten links in the tor-exit-notice file. Patch by Christian Kujau. o Minor bugfixes (code security): - Prevent a null-pointer dereference when receiving a data cell for a nonexistent stream when the circuit in question has an empty deliver window. We don't believe this is triggerable, since we don't currently allow deliver windows to become empty, but the logic is tricky enough that it's better to make the code robust. Fixes bug 5541; bugfix on 0.0.2pre14. - Fix a (harmless) integer overflow in cell statistics reported by some fast relays. Fixes bug 5849; bugfix on 0.2.2.1-alpha. - Fix our implementation of crypto_random_hostname() so it can't overflow on ridiculously large inputs. (No Tor version has ever provided this kind of bad inputs, but let's be correct in depth.) Fixes bug 4413; bugfix on 0.2.2.9-alpha. Fix by Stephen Palmateer. - Add a (probably redundant) memory clear between iterations of the router status voting loop, to prevent future coding errors where data might leak between iterations of the loop. Resolves ticket 6514. o Minor bugfixes (wrapper functions): - Abort if tor_vasprintf() fails in connection_printf_to_buf() (a utility function used in the control-port code). This shouldn't ever happen unless Tor is completely out of memory, but if it did happen and Tor somehow recovered from it, Tor could have sent a log message to a control port in the middle of a reply to a controller command. Fixes part of bug 3428; bugfix on 0.1.2.3-alpha. - Fix some (not actually triggerable) buffer size checks in usage of tor_inet_ntop(). Fixes bug 4434; bugfix on Tor 0.2.0.1-alpha. Patch by Anders Sundman. - Fix parsing of some corner-cases with tor_inet_pton(). Fixes bug 4515; bugfix on 0.2.0.1-alpha; fix by Anders Sundman. - Enforce correct return behavior of tor_vsscanf() when the '%%' pattern is used. Fixes bug 5558. Bugfix on 0.2.1.13. - Make our replacement implementation of strtok_r() compatible with the standard behavior of strtok_r(). Patch by nils. Fixes bug 5091; bugfix on 0.2.2.1-alpha. - Find more places in the code that should have been testing for invalid sockets using the SOCKET_OK macro. Required for a fix for bug 4533. Bugfix on 0.2.2.28-beta. o Minor bugfixes (code correctness): - Check return value of fputs() when writing authority certificate file. Fixes Coverity issue 709056; bugfix on 0.2.0.1-alpha. - When building Tor on Windows with -DUNICODE (not default), ensure that error messages, filenames, and DNS server names are always NUL-terminated when we convert them to a single-byte encoding. Fixes bug 5909; bugfix on 0.2.2.16-alpha. - Fix a memory leak when trying to launch a DNS request when the nameservers are unconfigurable. Fixes bug 5916; bugfix on Tor 0.1.2.1-alpha. - Correct file sizes when reading binary files on Cygwin, to avoid a bug where Tor would fail to read its state file. Fixes bug 6844; bugfix on 0.1.2.7-alpha. - Make sure to set *socket_error in all error cases in connection_connect(), so it can't produce a warning about errno being zero from errno_to_orconn_end_reason(). Bugfix on 0.2.1.1-alpha; resolves ticket 6028. - Initialize conn->addr to a valid state in spawn_cpuworker(). Fixes bug 4532; found by "troll_un". o Minor bugfixes (clients): - Allow one-hop directory-fetching circuits the full "circuit build timeout" period, rather than just half of it, before failing them and marking the relay down. This fix should help reduce cases where clients declare relays (or worse, bridges) unreachable because the TLS handshake takes a few seconds to complete. Fixes bug 6743; bugfix on 0.2.2.2-alpha, where we changed the timeout from a static 30 seconds. - Ensure we don't cannibalize circuits that are longer than three hops already, so we don't end up making circuits with 5 or more hops. Patch contributed by wanoskarnet. Fixes bug 5231; bugfix on 0.1.0.1-rc which introduced cannibalization. o Minor bugfixes (relays): - Don't publish a new relay descriptor when we reload our onion key, unless the onion key has actually changed. Fixes bug 3263 and resolves another cause of bug 1810. Bugfix on 0.1.1.11-alpha. - When relays refuse a "create" cell because their queue of pending create cells is too big (typically because their cpu can't keep up with the arrival rate), send back reason "resource limit" rather than reason "internal", so network measurement scripts can get a more accurate picture. Bugfix on 0.1.1.11-alpha; fixes bug 7037. - Exit nodes don't need to fetch certificates for authorities that they don't recognize; only directory authorities, bridges, and caches need to do that. Fixes part of bug 2297; bugfix on 0.2.2.11-alpha. o Minor bugfixes (directory authority / mirrors): - Avoid O(n^2) performance characteristics when parsing a large extrainfo cache. Fixes bug 5828; bugfix on 0.2.0.1-alpha. - Authorities no longer include any router in their microdescriptor consensuses for which they couldn't generate or agree on a microdescriptor. Fixes the second piece of bug 6404; fix on 0.2.2.6-alpha. - When checking for requested signatures on the latest consensus before serving it to a client, make sure to check the right consensus flavor. Bugfix on 0.2.2.6-alpha. - Fix an edge case where TestingTorNetwork is set but the authorities and relays all have an uptime of zero, so the private Tor network could briefly lack support for hidden services. Fixes bug 3886; bugfix on 0.2.2.18-alpha. - Directory caches no longer refuse to clean out descriptors because of missing v2 networkstatus documents, unless they're configured to retrieve v2 networkstatus documents. Fixes bug 4838; bugfix on 0.2.2.26-beta. Patch by Daniel Bryg. - Don't serve or accept v2 hidden service descriptors over a relay's DirPort. It's never correct to do so, and disabling it might make it more annoying to exploit any bugs that turn up in the descriptor-parsing code. Fixes bug 7149. o Minor bugfixes (hidden services, client-side): - Assert that hidden-service-related operations are not performed using single-hop circuits. Previously, Tor would assert that client-side streams are not attached to single-hop circuits, but not that other sensitive operations on the client and service side are not performed using single-hop circuits. Fixes bug 3332; bugfix on 0.0.6. - Avoid undefined behaviour when parsing the list of supported rendezvous/introduction protocols in a hidden service descriptor. Previously, Tor would have confused (as-yet-unused) protocol version numbers greater than 32 with lower ones on many platforms. Fixes bug 6827; bugfix on 0.2.0.10-alpha. Found by George Kadianakis. - Don't close hidden service client circuits which have almost finished connecting to their destination when they reach the normal circuit-build timeout. Previously, we would close introduction circuits which are waiting for an acknowledgement from the introduction point, and rendezvous circuits which have been specified in an INTRODUCE1 cell sent to a hidden service, after the normal CBT. Now, we mark them as 'timed out', and launch another rendezvous attempt in parallel. This behavior change can be disabled using the new CloseHSClientCircuitsImmediatelyOnTimeout option. Fixes part of bug 1297; bugfix on 0.2.2.2-alpha. o Minor bugfixes (hidden services, service-side): - Don't close hidden-service-side rendezvous circuits when they reach the normal circuit-build timeout. This behaviour change can be disabled using the new CloseHSServiceRendCircuitsImmediatelyOnTimeout option. Fixes the remaining part of bug 1297; bugfix on 0.2.2.2-alpha. - Don't launch more than 10 service-side introduction-point circuits for a hidden service in five minutes. Previously, we would consider launching more introduction-point circuits if at least one second had passed without any introduction-point circuits failing. Fixes bug 4607; bugfix on 0.0.7pre1. o Minor bugfixes (config option behavior): - If the user tries to set MyFamily on a bridge, refuse to do so, and warn about the security implications. Fixes bug 4657; bugfix on 0.2.0.3-alpha. - The "--quiet" and "--hush" options now apply not only to Tor's behavior before logs are configured, but also to Tor's behavior in the absense of configured logs. Fixes bug 3550; bugfix on 0.2.0.10-alpha. - Change the AllowDotExit rules so they should actually work. We now enforce AllowDotExit only immediately after receiving an address via SOCKS or DNSPort: other sources are free to provide .exit addresses after the resolution occurs. Fixes bug 3940; bugfix on 0.2.2.1-alpha. - Make "LearnCircuitBuildTimeout 0" work more reliably. Specifically, don't depend on the consensus parameters or compute adaptive timeouts when it is disabled. Fixes bug 5049; bugfix on 0.2.2.14-alpha. - After we pick a directory mirror, we would refuse to use it if it's in our ExcludeExitNodes list, resulting in mysterious failures to bootstrap for people who just wanted to avoid exiting from certain locations. Fixes bug 5623; bugfix on 0.2.2.25-alpha. - When told to add a bridge with the same digest as a preexisting bridge but a different addr:port, change the addr:port as requested. Previously we would not notice the change. Fixes half of bug 5603; fix on 0.2.2.26-beta. o Minor bugfixes (controller): - Allow manual 'authenticate' commands to the controller interface from netcat (nc) as well as telnet. We were rejecting them because they didn't come with the expected whitespace at the end of the command. Bugfix on 0.1.1.1-alpha; fixes bug 2893. - Report a real bootstrap problem to the controller on router identity mismatch. Previously we just said "foo", which probably made a lot of sense at the time. Fixes bug 4169; bugfix on 0.2.1.1-alpha. - When we receive a SIGHUP and the controller __ReloadTorrcOnSIGHUP option is set to 0 (which Vidalia version 0.2.16 now does when a SAVECONF attempt fails), perform other actions that SIGHUP usually causes (like reopening the logs). Fixes bug 5095; bugfix on 0.2.1.9-alpha. - Correctly handle checking the permissions on the parent directory of a control socket in the root directory. Bug found by Esteban Manchado VelÃ¡zquez. Fixes bug 5089; bugfix on Tor 0.2.2.26-beta. - End AUTHCHALLENGE error messages (in the control protocol) with a CRLF. Fixes bug 5760; bugfix on 0.2.2.36. o Minor bugfixes (network reading/writing): - Disable writing on marked-for-close connections when they are blocked on bandwidth, to prevent busy-looping in Libevent. Fixes bug 5263; bugfix on 0.0.2pre13, where we first added a special case for flushing marked connections. - Make sure that there are no unhandled pending TLS errors before reading from a TLS stream. We had checks in 0.1.0.3-rc, but lost them in 0.1.0.5-rc when we refactored read_to_buf_tls(). Bugfix on 0.1.0.5-rc; fixes bug 4528. - Detect SSL handshake even when the initial attempt to write the server hello fails. Fixes bug 4592; bugfix on 0.2.0.13-alpha. - If the client fails to set a reasonable set of ciphersuites during its v2 handshake renegotiation, allow the renegotiation to continue nevertheless (i.e. send all the required certificates). Fixes bug 4591; bugfix on 0.2.0.20-rc. o Minor bugfixes (other): - Exit nodes now correctly report EADDRINUSE and EADDRNOTAVAIL as resource exhaustion, so that clients can adjust their load to try other exits. Fixes bug 4710; bugfix on 0.1.0.1-rc, which started using END_STREAM_REASON_RESOURCELIMIT. - Don't check for whether the address we're using for outbound connections has changed until after the outbound connection has completed. On Windows, getsockname() doesn't succeed until the connection is finished. Fixes bug 5374; bugfix on 0.1.1.14-alpha. - Don't hold a Windows file handle open for every file mapping; the file mapping handle is sufficient. Fixes bug 5951; bugfix on 0.1.2.1-alpha. - Fix wrong TCP port range in parse_port_range(). Fixes bug 6218; bugfix on 0.2.1.10-alpha. - If we fail to write a microdescriptor to the disk cache, do not continue replacing the old microdescriptor file. Fixes bug 2954; bugfix on 0.2.2.6-alpha. o Minor bugfixes (log messages, path selection): - Downgrade "set buildtimeout to low value" messages to "info" severity; they were never an actual problem, there was never anything reasonable to do about them, and they tended to spam logs from time to time. Fixes bug 6251; bugfix on 0.2.2.2-alpha. - Rate-limit the "Weighted bandwidth is 0.000000" message, and add more information to it, so that we can track it down in case it returns again. Mitigates bug 5235. - Check CircuitBuildTimeout and LearnCircuitBuildTimeout in options_validate(); warn if LearnCircuitBuildTimeout is disabled and CircuitBuildTimeout is set unreasonably low. Resolves ticket 5452. - Issue a log message if a guard completes less than 40% of your circuits. Threshold is configurable by torrc option PathBiasNoticeRate and consensus parameter pb_noticepct. There is additional, off-by-default code to disable guards which fail too many circuits. Addresses ticket 5458. o Minor bugfixes (log messages, client): - Downgrade "Got a certificate, but we already have it" log messages from warning to info, except when we're a dirauth. Fixes bug 5238; bugfix on 0.2.1.7-alpha. - Fix the log message describing how we work around discovering that our version is the ill-fated OpenSSL 0.9.8l. Fixes bug 4837; bugfix on 0.2.2.9-alpha. - When logging about a disallowed .exit name, do not also call it an "invalid onion address". Fixes bug 3325; bugfix on 0.2.2.9-alpha. - Fix a log message suggesting that people contact a non-existent email address. Fixes bug 3448. - Rephrase the log message emitted if the TestSocks check is successful. Patch from Fabian Keil; fixes bug 4094. - Log (at debug level) whenever a circuit's purpose is changed. - Log SSL state transitions at log level DEBUG, log domain HANDSHAKE. This can be useful for debugging censorship events. Implements ticket 3264. - We now log which torrc file we're using on startup. Implements ticket 2444. - Rate-limit log messages when asked to connect anonymously to a private address. When these hit, they tended to hit fast and often. Also, don't bother trying to connect to addresses that we are sure will resolve to 127.0.0.1: getting 127.0.0.1 in a directory reply makes us think we have been lied to, even when the address the client tried to connect to was "localhost." Resolves ticket 2822. o Minor bugfixes (log messages, non-client): - Downgrade "eventdns rejected address" message to LOG_PROTOCOL_WARN. Fixes bug 5932; bugfix on 0.2.2.7-alpha. - Don't log that we have "decided to publish new relay descriptor" unless we are actually publishing a descriptor. Fixes bug 3942; bugfix on 0.2.2.28-beta. - Log which authority we're missing votes from when we go to fetch them from the other auths. - Replace "Sending publish request" log messages with "Launching upload", so that they no longer confusingly imply that we're sending something to a directory we might not even be connected to yet. Fixes bug 3311; bugfix on 0.2.0.10-alpha. - Warn when Tor is configured to use accounting in a way that can link a hidden service to some other hidden service or public address. Resolves ticket 6490. - Fix a minor formatting issue in one of tor-gencert's error messages. Fixes bug 4574. o Testing: - Update to the latest version of the tinytest unit testing framework. This includes a couple of bugfixes that can be relevant for running forked unit tests on Windows, and removes all reserved identifiers. - Avoid a false positive in the util/threads unit test by increasing the maximum timeout time. Fixes bug 6227; bugfix on 0.2.0.4-alpha. - Make it possible to set the TestingTorNetwork configuration option using AlternateDirAuthority and AlternateBridgeAuthority as an alternative to setting DirServer. Addresses ticket 6377. - Add a unit test for the environment_variable_names_equal() function. - A wide variety of new unit tests by Esteban Manchado VelÃ¡zquez. - Numerous new unit tests for functions in util.c and address.c by Anders Sundman. - The long-disabled benchmark tests are now split into their own ./src/test/bench binary. - The benchmark tests can now use more accurate timers than gettimeofday() when such timers are available. - Use tt_assert(), not tor_assert(), for checking for test failures. This makes the unit tests more able to go on in the event that one of them fails. o Build improvements: - Use the dead_strip option when building Tor on OS X. This reduces binary size by almost 19% when linking openssl and libevent statically, which we do for Tor Browser Bundle. - Provide a better error message about possible OSX Asciidoc failure reasons. Fixes bug 6436. - Detect attempts to build Tor on (as yet hypothetical) versions of Windows where sizeof(intptr_t) != sizeof(SOCKET). Partial fix for bug 4533. Bugfix on 0.2.2.28-beta. - On Windows, we now define the _WIN32_WINNT macros only if they are not already defined. This lets the person building Tor decide, if they want, to require a later version of Windows. - Our autogen.sh script now uses autoreconf to launch autoconf, automake, and so on. This is more robust against some of the failure modes associated with running the autotools pieces on their own. - Running "make version" now displays the version of Tor that we're about to build. Idea from katmagic; resolves issue 4400. - Make 'tor --digests' list hashes of all Tor source files. Bugfix on 0.2.2.4-alpha; fixes bug 3427. - New --enable-static-tor configure option for building Tor as statically as possible. Idea, general hackery and thoughts from Alexei Czeskis, John Gilmore, Jacob Appelbaum. Implements ticket 2702. - Limited, experimental support for building with nmake and MSVC. o Build requirements: - Building Tor with bufferevent support now requires Libevent 2.0.13-stable or later. Previous versions of Libevent had bugs in SSL-related bufferevents and related issues that would make Tor work badly with bufferevents. Requiring 2.0.13-stable also allows Tor with bufferevents to take advantage of Libevent APIs introduced after 2.0.8-rc. - Our build system requires automake 1.6 or later to create the Makefile.in files. Previously, you could have used 1.4. This only affects developers and people building Tor from git; people who build Tor from the source distribution without changing the Makefile.am files should be fine. - Detect when we try to build on a platform that doesn't define AF_UNSPEC to 0. We don't work there, so refuse to compile. o Build fixes (compile/link): - Format more doubles with %f, not %lf. Patch from grarpamp to make Tor build correctly on older BSDs again. Fixes bug 3894; bugfix on Tor 0.2.0.8-alpha. - When building with --enable-static-tor on OpenBSD, do not erroneously attempt to link -lrt. Fixes bug 5103. - Set _WIN32_WINNT to 0x0501 consistently throughout the code, so that IPv6 stuff will compile on MSVC, and compilation issues will be easier to track down. Fixes bug 5861. - Fix build and 64-bit compile warnings from --enable-openbsd-malloc. Fixes bug 6379. Bugfix on 0.2.0.20-rc. - Make Tor build correctly again with -DUNICODE -D_UNICODE defined. Fixes bug 6097; bugfix on 0.2.2.16-alpha. o Build fixes (other): - Use the _WIN32 macro throughout our code to detect Windows. (Previously we had used the obsolete 'WIN32' and the idiosyncratic 'MS_WINDOWS'.) - Properly handle the case where the build-tree is not the same as the source tree when generating src/common/common_sha1.i, src/or/micro-revision.i, and src/or/or_sha1.i. Fixes bug 3953; bugfix on 0.2.0.1-alpha. - During configure, search for library containing cos function as libm lives in libcore on some platforms (BeOS/Haiku). Linking against libm was hard-coded before. Fixes the first part of bug 4727; bugfix on 0.2.2.2-alpha. Patch and analysis by Martin Hebnes Pedersen. - Prevent a false positive from the check-spaces script, by disabling the "whitespace between function name and (" check for functions named 'op()'. o Packaging (RPM) changes: - Update our default RPM spec files to work with mock and rpmbuild on RHEL/Fedora. They have an updated set of dependencies and conflicts, a fix for an ancient typo when creating the "_tor" user, and better instructions. Thanks to Ondrej Mikle for the patch series. Fixes bug 6043. - On OpenSUSE, create the /var/run/tor directory on startup if it is not already created. Patch from Andreas Stieger. Fixes bug 2573. o Code refactoring (safety): - Do not use SMARTLIST_FOREACH for any loop whose body exceeds 10 lines. Also, don't nest them. Doing so in the past has led to hard-to-debug code. The new style is to use the SMARTLIST_FOREACH_{BEGIN,END} pair. Addresses issue 6400. - Use macros to indicate OpenSSL versions, so we don't need to worry about accidental hexadecimal bit shifts. - Use tor_sscanf() in place of scanf() in more places through the code. This makes us a little more locale-independent, and should help shut up code-analysis tools that can't tell a safe sscanf string from a dangerous one. - Convert more instances of tor_snprintf+tor_strdup into tor_asprintf. - Use the smartlist_add_asprintf() alias more consistently. o Code refactoring (consolidate): - A major revision to our internal node-selecting and listing logic. Tor already had at least two major ways to look at the question of "which Tor servers do we know about": a list of router descriptors, and a list of entries in the current consensus. With microdescriptors, we're adding a third. Having so many systems without an abstraction layer over them was hurting the codebase. Now, we have a new "node_t" abstraction that presents a consistent interface to a client's view of a Tor node, and holds (nearly) all of the mutable state formerly in routerinfo_t and routerstatus_t. - Move tor_gettimeofday_cached() into compat_libevent.c, and use Libevent's notion of cached time when possible. - Remove duplicate code for invoking getrlimit() from control.c. - Use OpenSSL's built-in SSL_state_string_long() instead of our own homebrewed ssl_state_to_string() replacement. Patch from Emile Snyder. Fixes bug 4653. - Change the symmetric cipher interface so that creating and initializing a stream cipher are no longer separate functions. o Code refactoring (separate): - Make a new "entry connection" struct as an internal subtype of "edge connection", to simplify the code and make exit connections smaller. - Split connection_about_to_close() into separate functions for each connection type. - Rewrite the listener-selection logic so that parsing which ports we want to listen on is now separate from binding to the ports we want. o Code refactoring (name changes): - Rename a handful of old identifiers, mostly related to crypto structures and crypto functions. By convention, our "create an object" functions are called "type_new()", our "free an object" functions are called "type_free()", and our types indicate that they are types only with a final "_t". But a handful of older types and functions broke these rules, with function names like "type_create" or "subsystem_op_type", or with type names like type_env_t. - Rename Tor functions that turn strings into addresses, so that "parse" indicates that no hostname resolution occurs, and "lookup" indicates that hostname resolution may occur. This should help prevent mistakes in the future. Fixes bug 3512. - Use the name "CERTS" consistently to refer to the new cell type; we were calling it CERT in some places and CERTS in others. - Use a TOR_INVALID_SOCKET macro when initializing a socket to an invalid value, rather than just -1. - Rename the bench_{aes,dmap} functions to test_*, so that tinytest can pick them up when the tests aren't disabled. Bugfix on 0.2.2.4-alpha which introduced tinytest. o Code refactoring (other): - Defensively refactor rend_mid_rendezvous() so that protocol violations and length checks happen in the beginning. Fixes bug 5645. - Remove the pure attribute from all functions that used it previously. In many cases we assigned it incorrectly, because the functions might assert or call impure functions, and we don't have evidence that keeping the pure attribute is worthwhile. Implements changes suggested in ticket 4421. - Move the replay-detection cache for the RSA-encrypted parts of INTRODUCE2 cells to the introduction point data structures. Previously, we would use one replay-detection cache per hidden service. Required by fix for bug 3460. - The helper programs tor-gencert, tor-resolve, and tor-checkkey no longer link against Libevent: they never used it, but our library structure used to force them to link it. o Removed features and files: - Remove all internal support for unpadded RSA. We never used it, and it would be a bad idea to start. - Remove some workaround code for OpenSSL 0.9.6 (which is no longer supported). - Remove some redundant #include directives throughout the code. Patch from Andrea Gelmini. - Remove some old code to remember statistics about which descriptors we've served as a directory mirror. The feature wasn't used and is outdated now that microdescriptors are around. - Remove some old code to work around even older versions of Tor that used forked processes to handle DNS requests. Such versions of Tor are no longer in use as relays. - The "torify" script no longer supports the "tsocks" socksifier tool, since tsocks doesn't support DNS and UDP right for Tor. Everyone should be using torsocks instead. Fixes bugs 3530 and 5180. Based on a patch by "ugh". - Remove the torrc.bridge file: we don't use it for anything, and it had become badly desynchronized from torrc.sample. Resolves bug 5622. o Documentation: - Begin a doc/state-contents.txt file to explain the contents of the Tor state file. Fixes bug 2987. - Clarify the documentation for the Alternate*Authority options. Fixes bug 6387. - Document the --defaults-torrc option, and the new semantics for overriding, extending, and clearing lists of options. Closes bug 4748. - Add missing man page documentation for consensus and microdesc files. Resolves ticket 6732. - Fix some typos in the manpages. Patch from A. Costa. Fixes bug 6500. o Documentation fixes: - Improve the manual's documentation for the NT Service command-line options. Addresses ticket 3964. - Clarify SessionGroup documentation slightly; resolves ticket 5437. - Document the changes to the ORPort and DirPort options, and the fact that {OR/Dir}ListenAddress is now unnecessary (and therefore deprecated). Resolves ticket 5597. - Correct a broken faq link in the INSTALL file. Fixes bug 2307. - Clarify that hidden services are TCP only. Fixes bug 6024.

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Tor 0.2.2.39 is released
by Roger Dingledine 15 Sep '12

15 Sep '12

Tor 0.2.2.39 fixes two more opportunities for remotely triggerable assertions. https://www.torproject.org/download/download Changes in version 0.2.2.39 - 2012-09-11 o Security fixes: - Fix an assertion failure in tor_timegm() that could be triggered by a badly formatted directory object. Bug found by fuzzing with Radamsa. Fixes bug 6811; bugfix on 0.2.0.20-rc. - Do not crash when comparing an address with port value 0 to an address policy. This bug could have been used to cause a remote assertion failure by or against directory authorities, or to allow some applications to crash clients. Fixes bug 6690; bugfix on 0.2.1.10-alpha.

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Tor 0.2.2.38 is released
by Roger Dingledine 19 Aug '12

19 Aug '12

Tor 0.2.2.38 fixes a rare race condition that can crash exit relays; fixes a remotely triggerable crash bug; and fixes a timing attack that could in theory leak path information. https://www.torproject.org/download/download Changes in version 0.2.2.38 - 2012-08-12 o Security fixes: - Avoid read-from-freed-memory and double-free bugs that could occur when a DNS request fails while launching it. Fixes bug 6480; bugfix on 0.2.0.1-alpha. - Avoid an uninitialized memory read when reading a vote or consensus document that has an unrecognized flavor name. This read could lead to a remote crash bug. Fixes bug 6530; bugfix on 0.2.2.6-alpha. - Try to leak less information about what relays a client is choosing to a side-channel attacker. Previously, a Tor client would stop iterating through the list of available relays as soon as it had chosen one, thus finishing a little earlier when it picked a router earlier in the list. If an attacker can recover this timing information (nontrivial but not proven to be impossible), they could learn some coarse-grained information about which relays a client was picking (middle nodes in particular are likelier to be affected than exits). The timing attack might be mitigated by other factors (see bug 6537 for some discussion), but it's best not to take chances. Fixes bug 6537; bugfix on 0.0.8rc1.

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