commit 0fbd44f0305a01a14bc7439f5ad66b59d9278a2d Author: Yawning Angel yawning@schwanenlied.me Date: Tue Jun 7 19:01:41 2016 +0000

Bug 19206: Include a 128 bit random tag as part of the domain isolator nonce.

When creating a domain isolation nonce, 128 bits of entropy is drawn from a cryptographic source and saved on a per-domain basis. The new circuit behavior is changed to regenerate the nonce, instead of incrementing a counter.

This allows the "right thing" to happen when the same tor instance is used across multiple Tor Browser sessions, for example when using a system wide tor, or a magic anonymity box. --- src/components/domain-isolator.js | 36 ++++++++++++++++++++++++++---------- 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/src/components/domain-isolator.js b/src/components/domain-isolator.js index 6cfd21e..769c47d 100644 --- a/src/components/domain-isolator.js +++ b/src/components/domain-isolator.js @@ -16,6 +16,9 @@ const Cc = Components.classes, Ci = Components.interfaces, Cu = Components.utils let logger = Cc["@torproject.org/torbutton-logger;1"] .getService(Components.interfaces.nsISupports).wrappedJSObject;

+// Import crypto object (FF 37+). +Cu.importGlobalProperties(["crypto"]); + // ## mozilla namespace. // Useful functionality for interacting with Mozilla services. let mozilla = {}; @@ -69,7 +72,7 @@ tor.socksProxyCredentials = function (originalProxy, domain) { // Check if we already have a nonce. If not, create // one for this domain. if (!tor.noncesForDomains.hasOwnProperty(domain)) { - tor.noncesForDomains[domain] = 0; + tor.noncesForDomains[domain] = tor.nonce(); } let proxy = originalProxy.QueryInterface(Ci.nsIProxyInfo); return mozilla.protocolProxyService @@ -77,21 +80,34 @@ tor.socksProxyCredentials = function (originalProxy, domain) { proxy.host, proxy.port, domain, // username - tor.noncesForDomains[domain].toString(), // password + tor.noncesForDomains[domain], // password proxy.flags, proxy.failoverTimeout, proxy.failoverProxy); };

-tor.newCircuitForDomain = function(domain) { - // Check if we already have a nonce. If not, create - // one for this domain. - if (!tor.noncesForDomains.hasOwnProperty(domain)) { - tor.noncesForDomains[domain] = 0; - } else { - tor.noncesForDomains[domain] += 1; +tor.nonce = function() { + // Generate a new 128 bit random tag. Strictly speaking both using a + // cryptographic entropy source and using 128 bits of entropy for the + // tag are likely overkill, as correct behavior only depends on how + // unlikely it is for there to be a collision. + let tag = new Uint8Array(16); + crypto.getRandomValues(tag); + + // Convert the tag to a hex string. + let tagStr = ""; + for (var i = 0; i < tag.length; i++) { + tagStr += (tag[i] >>> 4).toString(16); + tagStr += (tag[i] & 0x0F).toString(16); } - logger.eclog(3, "New domain isolation count " +tor.noncesForDomains[domain] + " for " + domain); + + return tagStr; +} + +tor.newCircuitForDomain = function(domain) { + // Re-generate the nonce for the domain. + tor.noncesForDomains[domain] = tor.nonce(); + logger.eclog(3, "New domain isolation for " + domain + ": " + tor.noncesForDomains[domain]); }

// __tor.isolateCircuitsByDomain()__.