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Message-ID: <10cc74ee-8587-8cdb-f85f-5724b370a2ce@linux.intel.com>
Date: Tue, 7 Apr 2020 17:54:27 +0300
From: Alexey Budankov <alexey.budankov@...ux.intel.com>
To: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
Alexei Starovoitov <ast@...nel.org>,
Ingo Molnar <mingo@...hat.com>,
James Morris <jmorris@...ei.org>,
Namhyung Kim <namhyung@...nel.org>,
Serge Hallyn <serge@...lyn.com>, Jiri Olsa <jolsa@...hat.com>,
Song Liu <songliubraving@...com>,
Andi Kleen <ak@...ux.intel.com>,
Stephane Eranian <eranian@...gle.com>,
Igor Lubashev <ilubashe@...mai.com>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel <linux-kernel@...r.kernel.org>,
"linux-security-module@...r.kernel.org"
<linux-security-module@...r.kernel.org>,
"selinux@...r.kernel.org" <selinux@...r.kernel.org>,
"intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
linux-man@...r.kernel.org
Subject: Re: [PATCH v8 00/12] Introduce CAP_PERFMON to secure system
performance monitoring and observability
On 07.04.2020 17:35, Arnaldo Carvalho de Melo wrote:
> Em Tue, Apr 07, 2020 at 11:30:14AM -0300, Arnaldo Carvalho de Melo escreveu:
>> [perf@...e ~]$ type perf
>> perf is hashed (/home/perf/bin/perf)
>> [perf@...e ~]$ getcap /home/perf/bin/perf
>> /home/perf/bin/perf = cap_sys_ptrace,cap_syslog,38+ep
>> [perf@...e ~]$ groups
>> perf perf_users
>> [perf@...e ~]$ id
>> uid=1002(perf) gid=1002(perf) groups=1002(perf),1003(perf_users) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
>> [perf@...e ~]$ perf top --stdio
>> Error:
>> Failed to mmap with 1 (Operation not permitted)
>> [perf@...e ~]$ perf record -a
>> ^C[ perf record: Woken up 1 times to write data ]
>> [ perf record: Captured and wrote 1.177 MB perf.data (1552 samples) ]
>>
>> [perf@...e ~]$ perf evlist
>> cycles:u
>> [perf@...e ~]$
>
> Humm, perf record falls back to cycles:u after initially trying cycles
> (i.e. kernel and userspace), lemme see trying 'perf top -e cycles:u',
> lemme test, humm not really:
>
> [perf@...e ~]$ perf top --stdio -e cycles:u
> Error:
> Failed to mmap with 1 (Operation not permitted)
> [perf@...e ~]$ perf record -e cycles:u -a sleep 1
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 1.123 MB perf.data (132 samples) ]
> [perf@...e ~]$
>
> Back to debugging this.
Could makes sense adding cap_ipc_lock to the binary to isolate from this:
kernel/events/core.c: 6101
if ((locked > lock_limit) && perf_is_paranoid() &&
!capable(CAP_IPC_LOCK)) {
ret = -EPERM;
goto unlock;
}
~Alexey
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