| Date | Fri, 5 Oct 2018 13:55:14 +0200 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH 00/11 v3] x86: load FPU registers on return to userland |
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On 2018-10-04 12:45:08 [-0400], Rik van Riel wrote: > Wait, so any thread can bypass its memory protection > keys, even if there is a seccomp filter preventing > it from calling the PKRU syscalls?
We have SYS_pkey_alloc +free and SYS_pkey_mprotect. For read/ write of the register value, libc is using and opcodes.
> Is that intended?
Either that or it ended like that because someone failed to attend a meeting where this was discussed. Here is something from pkeys(7):
| Protection keys have the potential to add a layer of security and | reliability to applications. But they have not been primarily designed as a | security feature. For instance, WRPKRU is a completely unprivileged | instruction, so pkeys are useless in any case that an attacker controls the | PKRU register or can execute arbitrary instructions.
Sebastian
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