Messages in this thread | | | Date | Thu, 9 Jul 2020 21:31:37 -0700 | From | Kees Cook <> | Subject | Re: [PATCH] proc/sysctl: make protected_* world readable |
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On Thu, Jul 09, 2020 at 04:51:15PM -0700, Julius Hemanth Pitti wrote: > protected_* files have 600 permissions which prevents > non-superuser from reading them. > > Container like "AWS greengrass" refuse to launch unless > protected_hardlinks and protected_symlinks are set. When > containers like these run with "userns-remap" or "--user" > mapping container's root to non-superuser on host, they > fail to run due to denied read access to these files. > > As these protections are hardly a secret, and do not > possess any security risk, making them world readable. > > Though above greengrass usecase needs read access to > only protected_hardlinks and protected_symlinks files, > setting all other protected_* files to 644 to keep > consistency. > > Fixes: 800179c9b8a1 ("fs: add link restrictions") > Signed-off-by: Julius Hemanth Pitti <jpitti@cisco.com>
Acked-by: Kees Cook <keescook@chromium.org>
I had originally proposed it as 0644, but Ingo asked that it have a more conservative default value[1]. I figured that given the settings can be discovered easily, it's not worth much. And if there are legit cases where things are improved, I don't have a problem switching this back.
Ingo, any thoughts on this now, 8 years later in the age of containers? :)
(One devil's advocate question: as a workaround, you are able to just change those files to 0644 after mounting /proc, yes? But regardless, why get in people's way for no justifiable reason.)
-Kees
[1] https://lore.kernel.org/lkml/20120105091704.GB3249@elte.hu/
-- Kees Cook
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