fix: allow unsandboxed renderers to request new privileges

[nornagon]

Description of Change

This used to be set for all processes, but was removed in #15229. This re-enables allow_new_privs but only for unsandboxed renderers. All other child processes will continue to have the default behaviour, which is to prevent new privileges via prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) (see prctl(2)).

Fixes #18521.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• tests are changed or added
• relevant documentation is changed or added
• PR title follows semantic commit guidelines
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Fixed an issue that prevented setuid binaries from being launched from the renderer process on Linux.

[deepak1556]

LGTM given the context from issue.

[nornagon]

Probably should also write a test for this.

[jkleinsc]

Can we add a test before merging?

[nornagon]

@jkleinsc PTAL, test added.

[release-clerk]

Release Notes Persisted

Fixed an issue that prevented setuid binaries from being launched from the renderer process on Linux.

[trop]

I was unable to backport this PR to "5-0-x" cleanly;
you will need to perform this backport manually.

[trop]

I was unable to backport this PR to "6-0-x" cleanly;
you will need to perform this backport manually.

[trop]

I was unable to backport this PR to "7-0-x" cleanly;
you will need to perform this backport manually.

[trop]

A maintainer has manually backported this PR to "7-0-x", please check out #19999

[trop]

A maintainer has manually backported this PR to "6-0-x", please check out #20023

[the-j0k3r]

A maintainer has manually backported this PR to "6-0-x", please check out #20023

Any chance this will be backported to Electron 5.0.13? Seems there is a regression for this see https://github.com/bus-stop/terminus/issues/84

Atom 1.47.0 latest version is using electron 5.0.13 which fails, earlier Atom 1.46.0 with electron 4.2.7 worked.

[trop]

@the-j0k3r has manually backported this PR to "5-0-x", please check out #23881

[the-j0k3r]

Has anyone checked this fix exists in newer electron version greater than 7.x?