Community learning discussion draft #2715

bcyphers · 2020-11-12T23:28:06Z

This is the first stab at adding community learning to Privacy Badger -- giving users the option to share de-identified information about the trackers they collect with EFF. Users can now choose to opt-in to community learning. Then, whenever Privacy Badger observes a new tracker for the first time, it will share the following information:

{
  page_host: full domain of the page that the user is on, 
  tracker_host: full domain of the third-party tracker, 
  tracking_action: type of action that Privacy Badger observed, one of ("cookie", "supercookie", "fingerprint").
}

Other things:

This is strictly opt-in, and no new data will be shared until a user checks the "community learning" box on the options page.
Community learning is separate from local learning: both can be enabled or disabled independently.
Community learning will not occur in incognito windows, even if local learning is enabled in incognito windows.
A random sample of new tracking actions will be reported. The proportion of new trackers reported is controlled by constants.CL_PROBABILITY. Right now it's set to 1.0, meaning every action will be reported.
To reduce network load, tracking actions will be reported after a random delay. The length of this delay is controlled by constants.MAX_CL_WAIT_TIME, currently set to 5 minutes.
Only trackers which are not already blocked or cookieblocked will be reported. Furthermore, only tracker/page pairs that are not already in the snitch map will be reported. If evil.com has a snitch map entry logging it tracking on example.com in the past, but evil.com is not yet blocked, the evil.com/example.com tracking action will not be reported.
To prevent duplicate reports, tracking actions that do get reported will be stored in an in-memory cache, HeuristicBlocker.previouslySharedTrackers. Tracking actions that are already present in the cache will not be reported again. Obviously, when the user restarts their browser, the cache will be cleared, but the goal is just to prevent crazy amounts of dupes. The size of the cache is capped by constants.CL_CACHE_SIZE.

This PR makes requests to "localhost:8080." If you want, you can set up a toy SQL server to test the logging.

On the server side, tracking actions will be stored in a SQL table that looks like this:

+----+---------------------+-----------------------------+-----------------------------+--------------+
| id | time                | page_host                   | tracker_host
| tracker_type |
+----+---------------------+-----------------------------+-----------------------------+--------------+
|  1 | 2020-10-28 10:38:48 | docs.python.org             | www.google.com
| cookie       |
|  2 | 2020-10-28 10:39:12 | docs.python.org             | adservice.google.com
| cookie       |
...

The server side is more up in the air, but for now, IP addresses and other identifying information will not be stored. Before this is deployed, we'll have some kind of privacy policy explaining exactly how logs etc. will be handled. We're still thinking through how best to prevent malicious reporting or other kinds of griefing.

We're thinking that the first version of community learning will be for informational purposes only -- the CL database will not automatically populate any block lists. This should reduce the incentive for bad actors to populate the database with bad data. We want to use the data to identify deficiencies in Badger Sett: what domains are we missing? on which domains do we need to crawl more widely? are there places where trackers don't appear unless a user logs in?

Eventually, it might make sense to auto-generate a community learning list, but for now, we just want to see what kind of data people are generating.

Feedback, criticism, concern are welcome. What do you think?

…is enabled - Create new SettingsMap variable, shareLearning, and default to false - pass tab_id to _recordPrevalence so that it can determine whether learning is enabled on a tab - update isLearningEnabled so that it returns true if either local or community learning is enabled; let _recordPrevalence figure out which kind of learning should be done - Create stub for function to share data with remote server

Since _recordPrevalence now checks for local learning enabled internally, update BadgerStorage.merge() to modify the blocklist directly.

update some comments

ablanathtanalba · 2020-12-03T18:16:38Z

This is great! And much appreciated how thought out it is from the get.
Here are some of my first thoughts while looking through this.

Starting at high level, definitely agreed that this DB for now should be used just for observational purposes, and no blocker lists should be made from it... yet.

ablanathtanalba · 2020-12-03T18:16:45Z

src/_locales/en_US/messages.json

@@ -173,6 +173,14 @@
        "message": "Learn in Private/Incognito windows",
        "description": "Checkbox label on the general settings page"
    },
+    "options_community_learning_setting": {
+        "message": "Enable community learning and share data about trackers",


I think changing this message to "Enable community learning and share data about trackers" would answer some questions that user might have without them having to read the lengthier warning message (which is great and should still be included on top of this)

ablanathtanalba · 2020-12-03T18:19:02Z

src/js/heuristicblocking.js

+    if (Math.random() < constants.CL_PROBABILITY) {
+      // check if we've shared this tracker recently
+      // note that this check comes after checking against the snitch map
+      let tr_str = page_host + '+' + tracker_host + '+' + tracker_type;


Adding some string sanitization and/or sanity checking the input values in this method wouldn't hurt, since they're about to get launched off in a POST

ablanathtanalba · 2020-12-03T18:20:45Z

src/_locales/en_US/messages.json

+        "message": "Enable community learning and share data about trackers",
+        "description": "Checkbox label on the general settings page"
+    },
+    "options_community_learning_warning": {


Should the link that explains what community learning is (and the decision making that led to it) be included in this message or the one above?

ablanathtanalba · 2020-12-03T18:22:19Z

src/js/constants.js

@@ -40,6 +40,17 @@ var exports = {
  TRACKING_THRESHOLD: 3,
  MAX_COOKIE_ENTROPY: 12,

+  // The max amount of time (in milliseconds) that PB will wait before sharing a
+  // tracking action with EFF for community learning
+  MAX_CL_WAIT_TIME: 5 * 60 * 1000, // five minutes


Good call on reducing network load with the reporting timeouts, but I'm curious why 5 minutes?

completely arbitrary!

bcyphers added 9 commits October 13, 2020 20:58

Pass tracker type to _recordPrevalence

7a8de57

Add reporting code to maybeShareTracker, fix syntax errors

c7e0ed3

Remove call to updateTrackerPrevalence from BadgerStorage.merge

d19ab03

Since _recordPrevalence now checks for local learning enabled internally, update BadgerStorage.merge() to modify the blocklist directly.

more local learning code is behind if statement

e55e0a3

Add community learning to options page

c0c1467

send host instead of origin

9d537a6

update some comments

Create in-memory cache to prevent duplicate reports

85bfd6b

Do not do community learning in incognito windows

86432ed

bcyphers added enhancement privacy General privacy issues; stuff that isn't about Privacy Badger's heuristic labels Nov 12, 2020

bcyphers requested review from ghostwords, andresbase and ablanathtanalba November 12, 2020 23:28

ablanathtanalba reviewed Dec 3, 2020

View reviewed changes

FominMax approved these changes Mar 13, 2021

View reviewed changes

ghostwords force-pushed the community-learning-test branch from e9a532f to 86432ed Compare August 3, 2021 22:39

ghostwords force-pushed the master branch from ed896f1 to 728cde2 Compare December 21, 2021 19:44

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Community learning discussion draft #2715

Community learning discussion draft #2715

bcyphers commented Nov 12, 2020

ablanathtanalba commented Dec 3, 2020

ablanathtanalba Dec 3, 2020

ablanathtanalba Dec 3, 2020

ablanathtanalba Dec 3, 2020

ablanathtanalba Dec 3, 2020

bcyphers Dec 11, 2020

Community learning discussion draft #2715

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Community learning discussion draft #2715

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