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([2001:df0:0:200c:dd49:18b7:7a1f:8116]) by smtp.gmail.com with ESMTPSA id y189sm342083pfb.135.2020.08.26.17.08.08 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 Aug 2020 17:08:10 -0700 (PDT) Subject: Re: [PATCH] m68k/kernel - wire up syscall_trace_enter/leave for m68k To: Geert Uytterhoeven Cc: John Paul Adrian Glaubitz , Linux/m68k , Andreas Schwab References: <1595823555-11103-1-git-send-email-schmitzmic@gmail.com> From: Michael Schmitz Message-ID: <855486ab-736a-19ad-35c2-174b5eb59898@gmail.com> Date: Thu, 27 Aug 2020 12:08:06 +1200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-m68k-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-m68k@vger.kernel.org Hi Geert, On 26/08/20 11:23 PM, Geert Uytterhoeven wrote: > Hi Michael, > > On Mon, Jul 27, 2020 at 6:19 AM Michael Schmitz wrote: >> m68k (other than Coldfire) uses syscall_trace for both trace entry >> and trace exit. Seccomp support requires separate entry points for >> trace entry and exit which are already provided for Coldfire. >> >> Replace syscall_trace by syscall_trace_enter and syscall_trace_leave >> in preparation for seccomp support. Check return code of >> syscall_trace_enter(), and skip syscall if nonzero. Return code >> will be left at what had been set by by ptrace or seccomp. >> >> No regression seen in testing with strace on ARAnyM. >> >> Signed-off-by: Michael Schmitz > Thanks for your patch! Thanks for looking into it! > >> Changes from RFC v1: >> >> - add return code check in do_trace_entry branch to enable syscall >> filtering (will return -EPERM) >> - change to use testl for return code check (suggested by Andreas Schwab) >> >> Changes from RFC v2: >> >> - don't set return code of filtered syscall - seccomp may want to set >> that for use by calling process. > As your email subject didn't contain "v3", b4[*] insists on picking up > RFC v2, and refuses to pick up the latest version, even when forced Argh - I thought that since the first two were tagged 'RFC', I could just restart with v1. Never heard of b4, sorry. > (msgid not present)... > > The patch itself looks good to me. Does it make sense to apply it before > we have real seccomp support? As far as I understand Adrian, it's needed as a prerequisite (though I admit there needs to be another patch adding the actual seccomp bits as well). With my rather limited test setup, this was all I could test. I've done enough damage with 'I think this is how it should work' patches to add untested stuff. In my not-at-all-humble opinion, the whole issue of whether to trigger a syscall abort on any non-zero return code, or just -1, is quite academic so I'd rather keep the broader non-zero test (unless someone points to a clear-cut reason why this is a Bad Thing). Cheers,     Michael > > [*] https://people.kernel.org/monsieuricon/introducing-b4-and-patch-attestation > > Gr{oetje,eeting}s, > > Geert >