From: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
To: "Lubashev, Igor" <ilubashe@akamai.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>,
Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jiri Olsa <jolsa@redhat.com>,
Alexey Budankov <alexey.budankov@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
James Morris <jmorris@namei.org>, Leo Yan <leo.yan@linaro.org>
Subject: Re: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
Date: Tue, 20 Aug 2019 14:13:42 -0300 [thread overview]
Message-ID: <20190820171342.GD3929@kernel.org> (raw)
In-Reply-To: <3f70f6be3a464ca5b4cf563433933245@usma1ex-dag1mb6.msg.corp.akamai.com>
Em Mon, Aug 19, 2019 at 10:22:07PM +0000, Lubashev, Igor escreveu:
> On Mon, August 19, 2019 at 12:51 PM Mathieu Poirier <mathieu.poirier@linaro.org> wrote:
> > On Thu, 15 Aug 2019 at 15:42, Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> wrote:
> > Things are working properly on your perf/cap branch. I tested with on both
> > x86 and ARM.
> Mathieu, you are probably testing with euid==0. If you were to test
> with euid!=0 but with CAP_SYSLOG and no libcap (and kptr_restrict=0,
> perf_event_paranoid=2), you would likely hit the bug that you
> identified in __perf_event__synthesize_kermel_mmap().
> See https://lkml.kernel.org/lkml/930a59730c0d495f8c5acf4f99048e8d@usma1ex-dag1mb6.msg.corp.akamai.com for the fix (Option 1 only or Options 1+2).
>
> 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@quaco 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@quaco 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,
Thanks and keep up the good work!
- Arnaldo
> - Igor
>
>
> > > > I am not sure how this can be fixed. I counted a total of 19
> > > > instances where kmap->ref_reloc_sym->XYZ is called, only 2 of wich
> > > > care to check if kmap->ref_reloc_sym is valid before proceeding. As
> > > > such I must hope that in the 17 other cases, kmap->ref_reloc_sym is
> > > > guaranteed to be valid. If I am correct then all we need is to
> > > > check for a valid pointer in _perf_event__synthesize_kernel_mmap().
> > > > Otherwise it will be a little harder.
> > > >
> > > > Mathieu
>
--
- Arnaldo
next prev parent reply other threads:[~2019-08-20 17:13 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 14:44 [PATCH v3 0/4] perf: Use capabilities instead of uid and euid Igor Lubashev
2019-08-07 14:44 ` [PATCH v3 1/4] perf: Add capability-related utilities Igor Lubashev
2019-08-12 19:43 ` Arnaldo Carvalho de Melo
2019-08-15 9:24 ` [tip:perf/core] tools build: Add capability-related feature detection tip-bot for Igor Lubashev
2019-08-15 9:25 ` [tip:perf/core] perf tools: Add helpers to use capabilities if present tip-bot for Igor Lubashev
2019-08-07 14:44 ` [PATCH v3 2/4] perf: Use CAP_SYS_ADMIN with perf_event_paranoid checks Igor Lubashev
2019-08-12 20:01 ` Arnaldo Carvalho de Melo
2019-08-12 20:15 ` Arnaldo Carvalho de Melo
2019-08-12 22:33 ` Lubashev, Igor
2019-08-13 13:20 ` Arnaldo Carvalho de Melo
2019-08-07 14:44 ` [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks Igor Lubashev
2019-08-14 18:04 ` Mathieu Poirier
2019-08-14 18:48 ` Arnaldo Carvalho de Melo
2019-08-14 18:52 ` Arnaldo Carvalho de Melo
2019-08-14 20:02 ` Lubashev, Igor
2019-08-15 15:01 ` Mathieu Poirier
2019-08-15 20:16 ` Mathieu Poirier
2019-08-15 21:42 ` Arnaldo Carvalho de Melo
2019-08-19 16:51 ` Mathieu Poirier
2019-08-19 22:22 ` Lubashev, Igor
2019-08-20 16:57 ` Mathieu Poirier
2019-08-20 17:13 ` Arnaldo Carvalho de Melo [this message]
2019-08-27 1:58 ` Lubashev, Igor
2019-08-15 22:27 ` Lubashev, Igor
2019-08-07 14:44 ` [PATCH v3 4/4] perf: Use CAP_SYS_ADMIN instead of euid==0 with ftrace Igor Lubashev
2019-08-12 20:22 ` Arnaldo Carvalho de Melo
2019-08-12 20:27 ` Arnaldo Carvalho de Melo
2019-08-12 20:29 ` Arnaldo Carvalho de Melo
2019-08-12 21:42 ` Mathieu Poirier
2019-08-13 13:23 ` Arnaldo Carvalho de Melo
2019-08-13 16:35 ` Mathieu Poirier
2019-08-15 9:27 ` [tip:perf/core] perf ftrace: Use CAP_SYS_ADMIN instead of euid==0 tip-bot for Igor Lubashev
2019-08-12 9:13 ` [PATCH v3 0/4] perf: Use capabilities instead of uid and euid Jiri Olsa
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