1587418 - Audit usage of nsIDocShellTreeItem in nsContentUtils::ShouldBlockReservedKeys

Status: RESOLVED FIXED

(Core :: DOM: Navigation, defect, P2)

Description

[Kannan Vijayan [:djvj]]

https://searchfox.org/mozilla-central/rev/7cc0f0e89cb40e43bf5c96906f13d44705401042/dom/base/nsContentUtils.cpp#9597

(Move state to BrowsingContext).

This code retrieves the same-type root from the docshell tree, and then checks the following property of the principal for the root document:

IsSitePermDeny(rootPrincipal, "shortcuts").

The callers of this is key-handling code. Does not seem like this method would be called in contexts where only in-process tree fragments are accessed, and that this query may cross process boundaries.

This check is likely done frequently, and not a candidate for IPC or active querying. The result of this query can be cached ahead of time in the BrowsingContext tree and used from there.

Comment 1

[Chris Peterson [:cpeterson]]

Kannan says replacing nsIDocShellTreeItem calls should block enabling Fission in Nightly (M6).

Comment 2

[Chris Peterson [:cpeterson]]

Auditing whether this use of nsIDocShellTreeItem breaks when Fission is enabled blocks Fission Nightly.

Comment 3

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

We can add a WindowContext synced field to the toplevel window context which records a cached permission value for the "shortcuts"_ns permission, much like how we handle the AutoplayPermission: https://searchfox.org/mozilla-central/rev/82c04b9cad5b98bdf682bd477f2b1e3071b004ad/docshell/base/WindowContext.h#49

Comment 4

[Steven MacLeod [:smacleod]]

Attachment: Bug 1587418 - cache shortcuts permission on WindowContext. r?farre

We now cache the shortcuts permission in a synced field on
WindowContext. This will allow checking the permission quickly and
without IPC when Fission is enabled and the top-level document is
in another process.

Comment 5

[Steven MacLeod [:smacleod]]

Attachment: Bug 1587418 - check shortcuts permission using WindowContext. r?farre

We now use the cached value of the shortcuts permission from
WindowContext if we cannot get a Browser. This will now work
when calling from a child where the top-level document is OOP.

Depends on D84182

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7e8123465017
cache shortcuts permission on WindowContext. r=farre
https://hg.mozilla.org/integration/autoland/rev/585e728dd155
check shortcuts permission using WindowContext. r=farre

Comment 7

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/7e8123465017
https://hg.mozilla.org/mozilla-central/rev/585e728dd155