commit ecb053899eb965c2778cf05479c26549d67f7956 Author: Karsten Loesing karsten.loesing@gmx.net Date: Fri Jun 10 13:28:42 2016 +0200

Sanitize TCP ports in bridge descriptors.

Implements #19317. --- CHANGELOG.md | 2 + .../bridgedescs/SanitizedBridgesWriter.java | 81 +++++++++++++++++----- src/main/webapp/index.html | 46 ++++++++++-- 3 files changed, 107 insertions(+), 22 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md index 24206ee..e17abad 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -4,6 +4,8 @@ - Add support for Bifroest's bridge descriptor tarballs. - Use a shutdown hook that gives currently running modules up to 10 minutes to finish properly, rather than killing them immediately. + - Replace TCP ports with hashes in @type bridge-network-status 1.1 + and @type bridge-server-descriptor 1.2.

* Minor changes - Remove quotes around base URL in index.json. diff --git a/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java b/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java index b787f78..b61cd30 100644 --- a/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java +++ b/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java @@ -138,7 +138,8 @@ public class SanitizedBridgesWriter extends CollecTorMain { while ((line = br.readLine()) != null) { String[] parts = line.split(","); if ((line.length() != ("yyyy-MM,".length() + 31 * 2) - && line.length() != ("yyyy-MM,".length() + 50 * 2)) + && line.length() != ("yyyy-MM,".length() + 50 * 2) + && line.length() != ("yyyy-MM,".length() + 83 * 2)) || parts.length != 2) { logger.warn("Invalid line in bridge-ip-secrets file " + "starting with '" + line.substring(0, 7) + "'! " @@ -218,8 +219,10 @@ public class SanitizedBridgesWriter extends CollecTorMain { scrubbedAddressPart = this.scrubIpv4Address(addressPart, fingerprintBytes, published); } + String scrubbedPort = this.scrubTcpPort(portPart, fingerprintBytes, + published); return (scrubbedAddressPart == null ? null : - scrubbedAddressPart + ":" + portPart); + scrubbedAddressPart + ":" + scrubbedPort); }

private String scrubIpv4Address(String address, byte[] fingerprintBytes, @@ -334,14 +337,42 @@ public class SanitizedBridgesWriter extends CollecTorMain { return sb.toString(); }

+ private String scrubTcpPort(String portString, byte[] fingerprintBytes, + String published) throws IOException { + if (portString.equals("0")) { + return "0"; + } else if (this.replaceIpAddressesWithHashes) { + if (this.persistenceProblemWithSecrets) { + /* There's a persistence problem, so we shouldn't scrub more TCP + * ports in this execution. */ + return null; + } + byte[] hashInput = new byte[2 + 20 + 33]; + int portNumber = Integer.parseInt(portString); + hashInput[0] = (byte) (portNumber >> 8); + hashInput[1] = (byte) portNumber; + System.arraycopy(fingerprintBytes, 0, hashInput, 2, 20); + String month = published.substring(0, "yyyy-MM".length()); + byte[] secret = this.getSecretForMonth(month); + System.arraycopy(secret, 50, hashInput, 22, 33); + byte[] hashOutput = DigestUtils.sha256(hashInput); + int hashedPort = ((((hashOutput[0] & 0xFF) << 8) + | (hashOutput[1] & 0xFF)) >> 2) | 0xC000; + return String.valueOf(hashedPort); + } else { + return "1"; + } + } + private byte[] getSecretForMonth(String month) throws IOException { if (!this.secretsForHashingIpAddresses.containsKey(month) - || this.secretsForHashingIpAddresses.get(month).length == 31) { - byte[] secret = new byte[50]; + || this.secretsForHashingIpAddresses.get(month).length < 83) { + byte[] secret = new byte[83]; this.secureRandom.nextBytes(secret); if (this.secretsForHashingIpAddresses.containsKey(month)) { System.arraycopy(this.secretsForHashingIpAddresses.get(month), 0, - secret, 0, 31); + secret, 0, + this.secretsForHashingIpAddresses.get(month).length); } if (month.compareTo( this.bridgeSanitizingCutOffTimestamp) < 0) { @@ -362,8 +393,8 @@ public class SanitizedBridgesWriter extends CollecTorMain { bw.close(); } catch (IOException e) { logger.warn("Could not store new secret " - + "to disk! Not calculating any IP address hashes in " - + "this execution!", e); + + "to disk! Not calculating any IP address or TCP port " + + "hashes in this execution!", e); this.persistenceProblemWithSecrets = true; throw new IOException(e); } @@ -471,11 +502,15 @@ public class SanitizedBridgesWriter extends CollecTorMain { fingerprintBytes, descPublicationTime); String nickname = parts[1]; + String scrubbedOrPort = this.scrubTcpPort(orPort, + fingerprintBytes, descPublicationTime); + String scrubbedDirPort = this.scrubTcpPort(dirPort, + fingerprintBytes, descPublicationTime); scrubbed.append("r " + nickname + " " + hashedBridgeIdentityBase64 + " " + hashedDescriptorIdentifier + " " + descPublicationTime - + " " + scrubbedAddress + " " + orPort + " " + dirPort - + "\n"); + + " " + scrubbedAddress + " " + scrubbedOrPort + " " + + scrubbedDirPort + "\n");

/* Sanitize any addresses in a lines using the fingerprint and * descriptor publication time from the previous r line. */ @@ -555,7 +590,7 @@ public class SanitizedBridgesWriter extends CollecTorMain { outputFile.getParentFile().mkdirs(); BufferedWriter bw = new BufferedWriter(new FileWriter( outputFile)); - bw.write("@type bridge-network-status 1.0\n"); + bw.write("@type bridge-network-status 1.1\n"); bw.write("published " + publicationTime + "\n"); bw.write(header.toString()); for (String scrubbed : scrubbedLines.values()) { @@ -595,6 +630,7 @@ public class SanitizedBridgesWriter extends CollecTorMain { String hashedBridgeIdentity = null; String address = null; String routerLine = null; + String scrubbedRouterLine = null; String scrubbedAddress = null; String masterKeyEd25519 = null; List<String> orAddresses = null; @@ -611,7 +647,12 @@ public class SanitizedBridgesWriter extends CollecTorMain { * the bridge identity fingerprint for replacing the IP address in * the scrubbed version. */ } else if (line.startsWith("router ")) { - address = line.split(" ")[2]; + String[] parts = line.split(" "); + if (parts.length != 6) { + logger.warn("Invalid router line: '" + line + "'. Skipping."); + return; + } + address = parts[2]; routerLine = line;

/* Store or-address parts in a list and sanitize them when we have @@ -671,6 +712,17 @@ public class SanitizedBridgesWriter extends CollecTorMain { } } } + String[] routerLineParts = routerLine.split(" "); + String nickname = routerLineParts[1]; + String scrubbedOrPort = this.scrubTcpPort(routerLineParts[3], + fingerprintBytes, published); + String scrubbedDirPort = this.scrubTcpPort(routerLineParts[4], + fingerprintBytes, published); + String scrubbedSocksPort = this.scrubTcpPort( + routerLineParts[5], fingerprintBytes, published); + scrubbedRouterLine = String.format("router %s %s %s %s %s%n", + nickname, scrubbedAddress, scrubbedOrPort, + scrubbedDirPort, scrubbedSocksPort); } catch (IOException e) { /* There's a persistence problem, so we shouldn't scrub more * IP addresses in this execution. */ @@ -692,10 +744,7 @@ public class SanitizedBridgesWriter extends CollecTorMain { /* When we reach the signature, we're done. Write the sanitized * descriptor to disk below. */ } else if (line.startsWith("router-signature")) { - String[] routerLineParts = routerLine.split(" "); - scrubbedDesc = "router " + routerLineParts[1] + " " - + scrubbedAddress + " " + routerLineParts[3] + " " - + routerLineParts[4] + " " + routerLineParts[5] + "\n"; + scrubbedDesc = scrubbedRouterLine; if (scrubbedOrAddresses != null) { for (String scrubbedOrAddress : scrubbedOrAddresses) { scrubbedDesc = scrubbedDesc += "or-address " @@ -915,7 +964,7 @@ public class SanitizedBridgesWriter extends CollecTorMain { outputFile.getParentFile().mkdirs(); BufferedWriter bw = new BufferedWriter(new FileWriter( outputFile, appendToFile)); - bw.write("@type bridge-server-descriptor 1.1\n"); + bw.write("@type bridge-server-descriptor 1.2\n"); bw.write(scrubbedDesc); if (descriptorDigestSha256Base64 != null) { bw.write("router-digest-sha256 " + descriptorDigestSha256Base64 diff --git a/src/main/webapp/index.html b/src/main/webapp/index.html index ccdeea2..bbc70f2 100644 --- a/src/main/webapp/index.html +++ b/src/main/webapp/index.html @@ -166,14 +166,14 @@ </tr> <tr> <td>Bridge Network Statuses</td> - <td><tt>@type bridge-network-status 1.0</tt></td> + <td><tt>@type bridge-network-status 1.1</tt></td> <td><a href="recent/bridge-descriptors/statuses/" class="btn btn-primary btn-xs">recent</a></td> <td><a href="archive/bridge-descriptors/" class="btn btn-primary btn-xs">archive</a></td> <td><a href="#type-bridge-network-status" class="btn btn-default btn-xs">format</a></td> </tr> <tr> <td>Bridge Server Descriptors</td> - <td><tt>@type bridge-server-descriptor 1.1</tt></td> + <td><tt>@type bridge-server-descriptor 1.2</tt></td> <td><a href="recent/bridge-descriptors/server-descriptors/" class="btn btn-primary btn-xs">recent</a></td> <td><a href="archive/bridge-descriptors/" class="btn btn-primary btn-xs">archive</a></td> <td><a href="#type-bridge-server-descriptor" class="btn btn-default btn-xs">format</a></td> @@ -447,6 +447,28 @@ with <tt>xx:xxxx</tt> being the hex-formatted 3 byte output of a similar hash function as described for IPv4 addresses. The only differences are that the input <tt>IP address</tt> is 16 bytes long and the <tt>secret</tt> is only 19 bytes long.</li></ul> +<li><b>Replace TCP port with TCP port hash:</b> It may be less obvious +that TCP ports need to be sanitized, but an unusual TCP port used by a +high-value bridge might still stand out and provide yet another way to +locate and block the bridge. +Therefore, each non-zero TCP port is replaced with a number in the range +from 49152 to 65535 that is the result of +<tt>H(port | bridge identity | secret)[:2] / 2^2 + 2^15 + 2^14</tt> +written as decimal number. +The input <tt>port</tt> is the 2-byte long binary representation of the +TCP port. +The <tt>bridge identity</tt> is the 20-byte long binary representation of +the bridge's long-term identity fingerprint. +The <tt>secret</tt> is a 33-byte long secure random string that changes +once per month for all descriptors and statuses published in that month. +<tt>H()</tt> is SHA-256. +The <tt>[:2]</tt> operator means that we pick the 2 most significant bytes +of the result. +The subsequent integer division and additions make sure that sanitized +ports are in the range from 49152 to 65535 which is reserved for private +services. +All operations assume inputs to be in network byte order. +TCP ports that are 0 in the original descriptor are left unchanged.</li> <li><b>Replace contact information:</b> If there is contact information in a descriptor, the contact line is changed to <tt>somebody</tt>.</li> @@ -468,7 +490,7 @@ descriptor including all signatures.</li> </ol>

<h3 id="type-bridge-network-status" class="hover">Bridge Network Statuses -<small><tt>@type bridge-network-status 1.0</tt></small> +<small><tt>@type bridge-network-status 1.1</tt></small> <a href="recent/bridge-descriptors/statuses/" class="btn btn-primary btn-xs">recent</a> <a href="archive/bridge-descriptors/" class="btn btn-primary btn-xs">archive</a> <a href="#type-bridge-network-status" class="hover">#</a> @@ -480,10 +502,19 @@ statuses, but with only a <tt>published</tt> line in the header and without any lines in the footer. The bridge descriptor archive tarballs contain all bridge descriptors of a given month, not just network statuses. +The format has changed over time to accomodate changes to the sanitizing +process, with earlier versions being: </p>

+<ul> +<li><font color="#666"><tt>@type bridge-network-status 1.0</tt> was the +first version.</font></li> +<li><tt>@type bridge-network-status 1.1</tt> introduced sanitized TCP +ports.</li> +</ul> + <h3 id="type-bridge-server-descriptor" class="hover">Bridge Server descriptors -<small><tt>@type bridge-server-descriptor 1.1</tt></small> +<small><tt>@type bridge-server-descriptor 1.2</tt></small> <a href="recent/bridge-descriptors/server-descriptors/" class="btn btn-primary btn-xs">recent</a> <a href="archive/bridge-descriptors/" class="btn btn-primary btn-xs">archive</a> <a href="#type-bridge-server-descriptor" class="hover">#</a> @@ -511,9 +542,12 @@ number of sanitized bridge extra-info descriptors was raised. As a result, there may be sanitized bridge server descriptors with version <tt>@type bridge-server-descriptor 1.0</tt> with and without those lines.</font></li> -<li><tt>@type bridge-server-descriptor 1.1</tt> added +<li><font color="#666"><tt>@type bridge-server-descriptor 1.1</tt> added <tt>master-key-ed25519</tt> lines and <tt>router-digest-sha256</tt> to -server descriptors published by bridges using an Ed25519 master key.</li> +server descriptors published by bridges using an Ed25519 master +key.</font></li> +<li><tt>@type bridge-server-descriptor 1.2</tt> introduced sanitized TCP +ports.</li> </ul>

<h3 id="type-bridge-extra-info" class="hover">Bridge Extra-info Descriptors