Bug 42513: Backport MozBug 1501744

Merge Info

Related Issues

• #42513
• mullvad-browser#xxxxx
• tor-browser-build#xxxxx
• Bug 1501744

Backporting

Timeline

• Immediate: patchset needed as soon as possible
• Next Minor Stable Release: patchset that needs to be verified in nightly before backport
• Eventually: patchset that needs to be verified in alpha before backport
• No Backport (preferred): patchset for the next major stable

(Optional) Justification

• Emergency security update: patchset fixes CVEs, 0-days, etc
• Censorship event: patchset enables censorship circumvention
• Critical bug-fix: patchset fixes a bug in core-functionality
• Consistency: patchset which would make development easier if it were in both the alpha and release branches; developer tools, build system changes, etc
• Sponsor required: patchset required for sponsor
• Localization: typos and other localization changes that should be also in the release branch
• Other: please explain

Merging

• Merge to tor-browser - !fixups to tor-browser-specific commits, new features, security backports
• Merge to base-browser - !fixups to base-browser-specific commits, new features to be shared with mullvad-browser, and security backports
  • NOTE: if your changeset includes patches to both base-browser and tor-browser please clearly label in the change description which commits should be cherry-picked to base-browser after merging

Issue Tracking

• Link resolved issues with appropriate Release Prep issue for changelog generation

Review

Request Reviewer

• Request review from an applications developer depending on modified system:
  • NOTE: if the MR modifies multiple areas, please /cc all the relevant reviewers (since gitlab only allows 1 reviewer)
  • accessibility : henry
  • android : clairehurst, dan
  • build system : boklm
  • extensions : ma1
  • firefox internals (XUL/JS/XPCOM) : jwilde, ma1
  • fonts : pierov
  • frontend (implementation) : henry
  • frontend (review) : donuts, richard
  • localization : henry, pierov
  • macOS : clairehurst, dan
  • nightly builds : boklm
  • rebases/release-prep : dan, ma1, pierov, richard
  • security : jwilde, ma1
  • signing : boklm, richard
  • updater : pierov
  • windows : jwilde, richard
  • misc/other : pierov, richard

Change Description

MozBug 1501744 (ffc9d633887208fe4810293c3b8db1f78da0ed61 on gecko-dev) solved several problems with touch/pen inputs on Linux.

For us, it implements the pressure spoofing when RFP is on, that currently doesn't work on Linux.

@dan since you found the drawing tablet, could you please review this one? 🙂. (even though it's a Moz commit, so testing I cherry-picked it successfully should be enough).

How Tested

Important: run export MOZ_USE_XINPUT2=1 on the shell from which you launch Tor Browser, or touch inputs will be ignored and detected as normal mouse inputs.

1. Then go to https://arkenfox.github.io/TZP/tests/pointerevent.html, tap reset and then tap the target area.
2. Before the patch: pressure leaks the actual value (and that you're using a pen input as a consequence).
3. After the patch: pressure is 0.5, and therefore is not distinguishable from a touchscreen (and possibly not even from a mouse).