Messages in this thread | | | Date | Wed, 29 Jul 2020 00:03:32 +0000 | From | Luis Chamberlain <> | Subject | Re: [PATCH] proc/sysctl: make protected_* world readable |
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On Thu, Jul 09, 2020 at 09:31:37PM -0700, Kees Cook wrote: > 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.
If we're going to to do this, can we please document why these are "protected" then?
Luis
> > 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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