Re: [PATCH v9 23/42] Documentation/x86: Add CET shadow stack description

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



* szabolcs:

>> alt shadow stack cannot be transparent to existing software anyway, it
>
> maybe not in glibc, but a libc can internally use alt shadow stack
> in sigaltstack instead of exposing a separate sigaltshadowstack api.
> (this is what a strict posix conform implementation has to do to
> support shadow stacks), leaking shadow stacks is not a correctness
> issue unless it prevents the program working (the shadow stack for
> the main thread likely wastes more memory than all the alt stack
> leaks. if the leaks become dominant in a thread the sigaltstack
> libc api can just fail).

It should be possible in theory to carve out pages from sigaltstack and
push a shadow stack page and a guard page as part of the signal frame.
As far as I understand it, the signal frame layout is not ABI, so it's
possible to hide arbitrary stuff in it.  I'm just saying that it looks
possible, not that it's a good idea.

Perhaps that's not realistic with 64K pages, though.

Thanks,
Florian




[Index of Archives]     [Linux Kernel]     [Kernel Newbies]     [x86 Platform Driver]     [Netdev]     [Linux Wireless]     [Netfilter]     [Bugtraq]     [Linux Filesystems]     [Yosemite Discussion]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Device Mapper]

  Powered by Linux