From: Alexey Budankov <alexey.budankov@linux.intel.com>
To: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Alexei Starovoitov <ast@kernel.org>,
Ingo Molnar <mingo@redhat.com>, James Morris <jmorris@namei.org>,
Namhyung Kim <namhyung@kernel.org>,
Serge Hallyn <serge@hallyn.com>, Jiri Olsa <jolsa@redhat.com>,
Song Liu <songliubraving@fb.com>, Andi Kleen <ak@linux.intel.com>,
Stephane Eranian <eranian@google.com>,
Igor Lubashev <ilubashe@akamai.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel <linux-kernel@vger.kernel.org>,
"linux-security-module@vger.kernel.org"
<linux-security-module@vger.kernel.org>,
"selinux@vger.kernel.org" <selinux@vger.kernel.org>,
"intel-gfx@lists.freedesktop.org"
<intel-gfx@lists.freedesktop.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
linux-man@vger.kernel.org
Subject: Re: [PATCH v8 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability
Date: Tue, 7 Apr 2020 20:17:14 +0300 [thread overview]
Message-ID: <ca8dc2ac-5a1d-d1a6-ca04-a4b5d9e9cbef@linux.intel.com> (raw)
In-Reply-To: <20200407164050.GC12003@kernel.org>
On 07.04.2020 19:40, Arnaldo Carvalho de Melo wrote:
> Em Tue, Apr 07, 2020 at 01:36:54PM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Tue, Apr 07, 2020 at 05:54:27PM +0300, Alexey Budankov escreveu:
>>> 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@five ~]$ type perf
>>>>> perf is hashed (/home/perf/bin/perf)
>>>>> [perf@five ~]$ getcap /home/perf/bin/perf
>>>>> /home/perf/bin/perf = cap_sys_ptrace,cap_syslog,38+ep
>>>>> [perf@five ~]$ groups
>>>>> perf perf_users
>>>>> [perf@five ~]$ 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@five ~]$ perf top --stdio
>>>>> Error:
>>>>> Failed to mmap with 1 (Operation not permitted)
>>>>> [perf@five ~]$ 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@five ~]$ perf evlist
>>>>> cycles:u
>>>>> [perf@five ~]$
>>>>
>>>> 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@five ~]$ perf top --stdio -e cycles:u
>>>> Error:
>>>> Failed to mmap with 1 (Operation not permitted)
>>>> [perf@five ~]$ 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@five ~]$
>>>>
>>>> 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;
>>> }
>>
>>
>> That did the trick, I'll update the documentation and include in my
>> "Committer testing" section:
>
> I ammended this to that patch, please check the wording:
>
> - Arnaldo
>
> diff --git a/Documentation/admin-guide/perf-security.rst b/Documentation/admin-guide/perf-security.rst
> index c0ca0c1a6804..ed33682e26b0 100644
> --- a/Documentation/admin-guide/perf-security.rst
> +++ b/Documentation/admin-guide/perf-security.rst
> @@ -127,12 +127,19 @@ taken to create such groups of privileged Perf users.
>
> ::
>
> - # setcap "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" perf
> - # setcap -v "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" perf
> + # setcap "cap_perfmon,cap_ipc_lock,cap_sys_ptrace,cap_syslog=ep" perf
> + # setcap -v "cap_perfmon,cap_ipc_lock,cap_sys_ptrace,cap_syslog=ep" perf
> perf: OK
> # getcap perf
> perf = cap_sys_ptrace,cap_syslog,cap_perfmon+ep
>
> +If the libcap installed doesn't yet support "cap_perfmon", use "38" instead,
> +i.e.:
> +
> +::
> +
> + # setcap "38,cap_ipc_lock,cap_sys_ptrace,cap_syslog=ep" perf
> +
> As a result, members of perf_users group are capable of conducting
> performance monitoring and observability by using functionality of the
> configured Perf tool executable that, when executes, passes perf_events
>
Looks good to me. The paragraph just above should then also be extended to
mention that perf_events subsystem memory limit is ignored due to usage of
CAP_IPC_LOCK:
"As a result, members of perf_users group are capable of conducting
performance monitoring and observability by using functionality of the
configured Perf tool executable that, when executes, passes perf_events
subsystem scope and perf_event_mlock_kb locking limit checks."
~Alexey
next prev parent reply other threads:[~2020-04-07 17:17 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-02 8:42 [PATCH v8 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability Alexey Budankov
2020-04-02 8:45 ` [PATCH v8 01/12] capabilities: introduce CAP_PERFMON to kernel and user space Alexey Budankov
2020-04-22 12:17 ` [tip: perf/core] capabilities: Introduce " tip-bot2 for Alexey Budankov
2020-04-02 8:46 ` [PATCH v8 02/12] perf/core: open access to the core for CAP_PERFMON privileged process Alexey Budankov
2020-04-22 12:17 ` [tip: perf/core] perf/core: Open " tip-bot2 for Alexey Budankov
2020-04-02 8:47 ` [PATCH v8 03/12] perf/core: open access to probes " Alexey Budankov
2020-04-22 12:17 ` [tip: perf/core] " tip-bot2 for Alexey Budankov
2020-04-02 8:47 ` [PATCH v8 04/12] perf tool: extend Perf tool with CAP_PERFMON capability support Alexey Budankov
2020-04-03 11:08 ` Jiri Olsa
2020-04-03 13:08 ` Alexey Budankov
2020-04-04 2:18 ` Namhyung Kim
2020-04-04 8:18 ` Alexey Budankov
2020-04-22 12:17 ` [tip: perf/core] perf tools: Support CAP_PERFMON capability tip-bot2 for Alexey Budankov
2020-04-02 8:48 ` [PATCH v8 05/12] drm/i915/perf: open access for CAP_PERFMON privileged process Alexey Budankov
2020-04-22 12:17 ` [tip: perf/core] drm/i915/perf: Open " tip-bot2 for Alexey Budankov
2020-04-02 8:48 ` [PATCH v8 06/12] trace/bpf_trace: open " Alexey Budankov
2020-04-22 12:17 ` [tip: perf/core] trace/bpf_trace: Open " tip-bot2 for Alexey Budankov
2020-04-02 8:49 ` [PATCH v8 07/12] powerpc/perf: open " Alexey Budankov
2020-04-22 12:17 ` [tip: perf/core] " tip-bot2 for Alexey Budankov
2020-04-02 8:50 ` [PATCH v8 08/12] parisc/perf: " Alexey Budankov
2020-04-22 12:17 ` [tip: perf/core] " tip-bot2 for Alexey Budankov
2020-04-02 8:51 ` [PATCH v8 09/12] drivers/perf: " Alexey Budankov
2020-04-22 12:17 ` [tip: perf/core] drivers/perf: Open " tip-bot2 for Alexey Budankov
2020-04-02 8:53 ` [PATCH v8 10/12] drivers/oprofile: open " Alexey Budankov
2020-04-22 12:17 ` [tip: perf/core] drivers/oprofile: Open " tip-bot2 for Alexey Budankov
2020-04-02 8:54 ` [PATCH v8 11/12] doc/admin-guide: update perf-security.rst with CAP_PERFMON information Alexey Budankov
2020-04-22 12:17 ` [tip: perf/core] doc/admin-guide: Update " tip-bot2 for Alexey Budankov
2020-04-02 8:54 ` [PATCH v8 12/12] doc/admin-guide: update kernel.rst " Alexey Budankov
2020-04-05 14:10 ` Arnaldo Carvalho de Melo
2020-04-05 14:41 ` Alexey Budankov
2020-04-05 14:54 ` Alexey Budankov
2020-04-05 15:05 ` Arnaldo Carvalho de Melo
2020-04-05 15:51 ` Alexey Budankov
2020-04-22 12:17 ` [tip: perf/core] " tip-bot2 for Alexey Budankov
2020-04-07 14:30 ` [PATCH v8 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability Arnaldo Carvalho de Melo
2020-04-07 14:35 ` Arnaldo Carvalho de Melo
2020-04-07 14:54 ` Alexey Budankov
2020-04-07 16:36 ` Arnaldo Carvalho de Melo
2020-04-07 16:40 ` Arnaldo Carvalho de Melo
2020-04-07 17:17 ` Alexey Budankov [this message]
2020-04-07 16:52 ` Alexey Budankov
2020-04-07 17:02 ` Arnaldo Carvalho de Melo
2020-04-07 17:32 ` Alexey Budankov
2020-04-07 16:56 ` Arnaldo Carvalho de Melo
2020-04-07 17:23 ` Arnaldo Carvalho de Melo
2020-07-10 13:31 ` Ravi Bangoria
2020-07-10 14:30 ` Alexey Budankov
2020-07-10 17:09 ` Arnaldo Carvalho de Melo
2020-07-13 9:48 ` Alexey Budankov
2020-07-13 12:17 ` Arnaldo Carvalho de Melo
2020-07-13 12:37 ` Alexey Budankov
2020-07-13 18:51 ` Arnaldo Carvalho de Melo
2020-07-14 10:59 ` Peter Zijlstra
2020-07-14 15:27 ` Arnaldo Carvalho de Melo
2020-07-21 13:06 ` Alexey Budankov
2020-07-22 11:30 ` Arnaldo Carvalho de Melo
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