linux-kernel - RE: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr

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Message-ID: <c647400a6c164bdab2cadfb7c0f1b519@usma1ex-dag1mb6.msg.corp.akamai.com>
Date:   Tue, 27 Aug 2019 01:58:35 +0000
From:   "Lubashev, Igor" <ilubashe@...mai.com>
To:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>
CC:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jiri Olsa <jolsa@...hat.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>,
        "Peter Zijlstra" <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        "Alexander Shishkin" <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Leo Yan <leo.yan@...aro.org>
Subject: RE: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks

On Tue, August 20, 2019 at 1:14 PM Arnaldo Carvalho de Melo <arnaldo.melo@...il.com> wrote:
> > Arnaldo, once we decide what the right fix is, I am happy to post the
> update (options 1, 1+2) as a patch series.
> 
> I think you should get the checks for ref_reloc_sym in place so as to make the
> code overall more robust, and also go on continuing to make the checks in
> tools/perf/ to match what is checked on the other side of the mirror, i.e. by
> the kernel, so from a quick read, please put first the robustness patches
> (check ref_reloc_sym) do your other suggestions and update the warnings,
> then refresh the two patches that still are not in my perf/core branch:
> 
> [acme@...co perf]$ git rebase perf/core
> First, rewinding head to replay your work on top of it...
> Applying: perf tools: Use CAP_SYS_ADMIN with perf_event_paranoid checks
> Applying: perf symbols: Use CAP_SYSLOG with kptr_restrict checks
> [acme@...co perf]$
> 
> I've pushed out perf/cap, so you can go from there as it is rebased on my
> current perf/core.
> 
> Then test all these cases: with/without libcap, with euid==0 and different
> than zero, with capabilities, etc, patch by patch so that we don't break
> bisection nor regress,

All done.  I've posted the update as a new follow-up series: https://lkml.kernel.org/lkml/1566869956-7154-1-git-send-email-ilubashe@akamai.com/ rebased on your perf/core.

I've tested 336 permutations (see the new cover).  In particular, I was able to reproduce the crash on perf/cap and confirm that no permutation can cause such crashes for any of the patches in the series.

> Thanks and keep up the good work!
> 
> - Arnaldo

- Igor