1400139 - Add telemetry for how often window.content is used from untrusted code

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, enhancement, P2)

Description

[Boris Zbarsky [:bzbarsky]]

Specifically, the plan is to do the following:

1) Make the property non-enumerable (needs some codegen changes).
2) Add a counter for how often the window resolve hook is run for a property named
   "content".  This will also trap sets of "content" and "var content", so might
   not turn out to be useful unless it's very very low; it's basically an upper 
   bound on "content" usage.
3) Add a counter for how often the getter is called from untrusted code.

Comment 1

[Andrew Overholt [:overholt]]

Since we need this for removing it (bug 1400140), I guess P2 is appropriate.

Comment 2

[Boris Zbarsky [:bzbarsky]]

Actually, I don't think #2 is at all useful, because we would trigger that resolve hook when setting up the window object itself...  I'm going to do the other pieces, though.

I did try to poke at GitHub searching for "content in window" (yes, I checked that it finds other detection code using a similar search, e.g. "scrollX in window"), and don't obviously see anyone using it for sniffing.

Comment 3

[Boris Zbarsky [:bzbarsky]]

Attachment: part 1. Add infrastructure for marking WebIDL interface members as non-enumerable

MozReview-Commit-ID: 9F0ZNverS63

Comment 4

[Boris Zbarsky [:bzbarsky]]

Attachment: part 2. Make window.content non-enumerable

MozReview-Commit-ID: LQkEkdG8wKf

Comment 5

[Boris Zbarsky [:bzbarsky]]

Attachment: part 3. Add a use counter when the window.content getter is called from untrusted code

MozReview-Commit-ID: LFMK7lxs46Z

Comment 6

[Nika Layzell [:nika] (ni? for response)]

Comment on attachment 8908949 [details] [diff] [review]
part 3.  Add a use counter when the window.content getter is called from untrusted code

Review of attachment 8908949 [details] [diff] [review]:
-----------------------------------------------------------------

This patch adds a warning and, as far as I can tell, no usage counter, so the commit message is a bit confusing :-/

Comment 7

[Boris Zbarsky [:bzbarsky]]

Comment on attachment 8908949 [details] [diff] [review]
part 3.  Add a use counter when the window.content getter is called from untrusted code

> This patch adds a warning and, as far as I can tell, no usage counter

Everything in nsDeprecatedOperationList.h automatically gets a usage counter.  See http://searchfox.org/mozilla-central/rev/6769c4c331c85870ac3e7bf61968db98c16e4777/dom/base/UseCounter.h#29-32 and http://searchfox.org/mozilla-central/rev/6769c4c331c85870ac3e7bf61968db98c16e4777/dom/base/nsDocument.cpp#10543-10546 and so forth.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/6ecbba14b2f3
part 1.  Add infrastructure for marking WebIDL interface members as non-enumerable.  r=qdot
https://hg.mozilla.org/integration/mozilla-inbound/rev/5bc10c68bbf7
part 2.  Make window.content non-enumerable.  r=mystor
https://hg.mozilla.org/integration/mozilla-inbound/rev/df23db5d453e
part 3.  Add a use counter when the window.content getter is called from untrusted code.  r=mystor

Comment 9

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/6ecbba14b2f3
https://hg.mozilla.org/mozilla-central/rev/5bc10c68bbf7
https://hg.mozilla.org/mozilla-central/rev/df23db5d453e