linux-kernel - Re: arm64: Register modification during syscall entry/exit stop

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sun, 31 May 2020 12:20:51 -0400
From:   Keno Fischer <keno@...iacomputing.com>
To:     Dave Martin <Dave.Martin@....com>
Cc:     Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Kyle Huey <khuey@...nos.co>, Oleg Nesterov <oleg@...hat.com>,
        linux-arm-kernel@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: arm64: Register modification during syscall entry/exit stop

> Can't PTRACE_SYSEMU be emulated by using PTRACE_SYSCALL, cancelling the
> syscall at the syscall enter stop, then modifying the regs at the
> syscall exit stop?

Yes, it can. The idea behind SYSEMU is to be able to save half the
ptrace traps that would require, in theory making the ptracer
a decent amount faster. That said, the x7 issue is orthogonal to
SYSEMU, you'd have the same issues if you used PTRACE_SYSCALL.


Keno