Messages in this thread | | | From | Andy Lutomirski <> | Date | Sat, 17 Feb 2018 18:12:18 +0000 | Subject | Re: [PATCH 0/2] efivars: reading variables can generate SMIs |
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On Fri, Feb 16, 2018 at 10:03 PM, Matthew Garrett <mjg59@google.com> wrote: > On Fri, Feb 16, 2018 at 2:02 PM Luck, Tony <tony.luck@intel.com> wrote: > >> > If the default is 600 then it makes sense to allow a privileged service > to >> > selectively make certain variables world readable at runtime. > >> As soon as you make one variable world readable you are vulnerable to >> a local user launching a DoS attack by reading that variable over and over >> generating a flood of SMIs. > > I'm not terribly worried about untrusted users on my laptop, but I would > prefer to run as little code as root as possible.
I think that, for the most part, systemwide configuration should not be accessible to non-root. Unprivileged users, in general, have no legitimate reason to know that my default boot is Boot0000* Fedora HD(1,GPT,ee...,0x800,0x64000)/File(\EFI\fedora\shim.efi). Even more so if I'm network booting.
Alternatively, we could call this a distro issue. Distros could easily change the permissions on /sys/firmware/efi/efivars to disallow unprivileged access.
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