[Pkg-mozext-maintainers] Bug#919557: Bug#919557: Bug#922944: handling symbolic links in webextensions

Ximin Luo infinity0 at debian.org
Sun Apr 26 00:25:06 BST 2020

Dmitry Smirnov:
> On Sunday, 26 April 2020 8:20:28 AM AEST Ximin Luo wrote:
>> As I mentioned on firefox bugzilla [1], I have figured out the exact place
>> in the firefox code responsible for this issue.
>> [1] https://bugzilla.mozilla.org/show_bug.cgi?id=1420286
> Without looking into the proposed fix, I think there are few reasons not to 
> make any alterations:
> As much as I like the idea of symlinking resources from webextensions, 
> incorporating those resources at build-time make packaged addons less 
> fragile. Frequently synlinked Javascript libraries change/break often enough 
> on "apt upgrade" and when it happens maintainer have to resort to bundling of 
> working versions anyway but not before users experience (and report) 
> breakage.
> Diverging from upstream may not be desirable. I'm sure Firefox is difficult 
> enough to maintain without adding specific logic that have to be tested.

The suggested patch is removing 3 lines, and changing 1 line. This is not hard to maintain. I see plenty of other patches in this firefox package already much larger than this, and I maintain larger patches in other similarly complex packages.

> IMHO symlinks sandboxing was done upstream for security reasons. We may not 
> fully understand implication of changing this behaviour.

The source code doesn't mention any particular reason, and one person on the upstream bug report mentions it in such an off-the-cuff and non-explanatory way I can't take it into account as a serious data point. We shouldn't just let a mere mention of "security" scare us into not touching stuff and using our own reasoning to fix bugs.

And I *did* think about the possible security considerations, as I explained in my previous email, and derived my suggested patch based on these considerations. (FWIW, I have done and am doing various types of security work professionally, and I'm confident about this type of reasoning in general.)

> I've already discovered and documented working solution to incorporating 
> resources to webextension packages at build time. Updating packages is easy 
> enough and should be even possible with binNMUs to refresh their bundled 
> resources. That approach might be considered "good enough".

This is static linking, and in Debian we generally avoid doing that. I am not saying you shouldn't do it for your package, but we also shouldn't shy away from fixing infrastructural situations that force us into it.


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