Messages in this thread | | | From | Florian Weimer <> | Subject | Re: [PATCH v11 9/9] x86: Disallow vsyscall emulation when CET is enabled | Date | Tue, 25 Aug 2020 11:14:37 +0200 |
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* Andy Lutomirski:
> On Mon, Aug 24, 2020 at 5:30 PM Yu-cheng Yu <yu-cheng.yu@intel.com> wrote: >> >> From: "H.J. Lu" <hjl.tools@gmail.com> >> >> Emulation of the legacy vsyscall page is required by some programs built >> before 2013. Newer programs after 2013 don't use it. Disallow vsyscall >> emulation when Control-flow Enforcement (CET) is enabled to enhance >> security. > > NAK. > > By all means disable execute emulation if CET-IBT is enabled at the > time emulation is attempted, and maybe even disable the vsyscall page > entirely if you can magically tell that CET-IBT will be enabled when a > process starts, but you don't get to just disable it outright on a > CET-enabled kernel.
Yeah, we definitely would have to revert/avoid this downstream. People definitely want to run glibc-2.12-era workloads on current kernels. Thanks for catching it.
Florian
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