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[222.152.189.137]) by smtp.gmail.com with ESMTPSA id o1sm994113pfk.152.2021.06.22.22.26.24 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 22 Jun 2021 22:26:32 -0700 (PDT) Subject: Re: Kernel stack read with PTRACE_EVENT_EXIT and io_uring threads To: "Eric W. Biederman" , Linus Torvalds References: <924ec53c-2fd9-2e1c-bbb1-3fda49809be4@gmail.com> <87eed4v2dc.fsf@disp2133> <5929e116-fa61-b211-342a-c706dcb834ca@gmail.com> <87fsxjorgs.fsf@disp2133> <87h7hpbojt.fsf@disp2133> <20c787ec-4a3c-061c-c649-5bc3e7ef0464@gmail.com> Cc: Al Viro , linux-arch , Jens Axboe , Oleg Nesterov , Linux Kernel Mailing List , Richard Henderson , Ivan Kokshaysky , Matt Turner , alpha , Geert Uytterhoeven , linux-m68k , Arnd Bergmann , Tejun Heo , Kees Cook , Tetsuo Handa , John Paul Adrian Glaubitz From: Michael Schmitz Message-ID: <55bdad37-187b-e1f5-a359-c5206b20ff4d@gmail.com> Date: Wed, 23 Jun 2021 17:26:22 +1200 User-Agent: Mozilla/5.0 (X11; Linux ppc; rv:45.0) Gecko/20100101 Icedove/45.4.0 MIME-Version: 1.0 In-Reply-To: <20c787ec-4a3c-061c-c649-5bc3e7ef0464@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Eric, Am 23.06.2021 um 09:48 schrieb Michael Schmitz: >> >> The challenging ones are /proc/pid/syscall and seccomp which want to see >> all of the system call arguments. I think every architecture always >> saves the system call arguments unconditionally, so those cases are >> probably not as interesting. But they certain look like they could be >> trouble. > > Seccomp hasn't yet been implemented on m68k, though I'm working on that > with Adrian. The sole secure_computing() call will happen in > syscall_trace_enter(), so all system call arguments have been saved on > the stack. > > Haven't looked at /proc/pid/syscall yet ... Not supported at present (no HAVE_ARCH_TRACEHOOK for m68k). And the syscall_get_arguments I wrote for seccomp support only copies the first five data registers, which are always saved. Cheers, Michael