Messages in this thread | | | From | pageexec@freemail ... | Date | Mon, 06 Jun 2011 23:53:09 +0200 | Subject | Re: [PATCH v5 9/9] x86-64: Add CONFIG_UNSAFE_VSYSCALLS to feature-removal-schedule |
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On 7 Jun 2011 at 5:40, Linus Torvalds wrote:
> On Tue, Jun 7, 2011 at 3:46 AM, <pageexec@freemail.hu> wrote: > > > >> I'm happy with perhaps moving away from the fixed-address vdso, > > > > it's not about the vdso that has been mmap'ed and randomized for quite some > > time now. it's about the amd64 specific vsyscall page. > > Duh. What do you think that thing is? It's a special fixed-address > vdso.
that we call the vsyscall page and not some random vdso thing, they're quite different, that's why there's this whole patch series, duh.
> What I complain about in the patch series was (specifically) that I > think the naming sucks and (non-specifically) that the whole series is > annoying. > > The config name is misleading and pointlessly scary - the whole thing > is not in itself "unsafe", so calling it that is just wrong.
if it's safe to have the vsyscall page at a fixed address, then you surely wouldn't object to have its replacement at a fixed address as well, would you? yes/no? (if it's a 'yes' then you'd better have some non-security arguments too ;)
> We *definitely* don't want to name it in a way that makes some random > person just turn it off because it's scary, since the random person > *shouldn't* turn it off today. Comprende?
actually you confused yourself and got it backwards. we want everyone sane who cares an iota about security to turn off the legacy/fixed address vsyscall as soon as possible else it's a pointless exercise. capito?
> If we can replace the vsyscall page with a page fault or int3 or > whatever, and it's only used for the 'time()' system call, just do it.
i agree fully, there's no real reason for a config option imho, i never had one in PaX and noone ever complained let alone noticed it (except perhaps for failed exploit attempts but that's by design).
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