Re: [PATCH v8 12/12] doc/admin-guide: update kernel.rst with CAP_PERFMON information

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 12/12] doc/admin-guide: update kernel.rst with CAP_PERFMON information
Date: Sun, 5 Apr 2020 17:54:37 +0300	[thread overview]
Message-ID: <966244a1-2a2d-8e47-b805-2effa46fe8cd@linux.intel.com> (raw)
In-Reply-To: <eb7fd0bd-4043-b51c-9b19-ee0a1d1849e9@linux.intel.com>


On 05.04.2020 17:41, Alexey Budankov wrote:
> 
> On 05.04.2020 17:10, Arnaldo Carvalho de Melo wrote:
>> Em Thu, Apr 02, 2020 at 11:54:39AM +0300, Alexey Budankov escreveu:
>>>
>>> Update kernel.rst documentation file with the information
>>> related to usage of CAP_PERFMON capability to secure performance
>>> monitoring and observability operations in system.
>>
>> This one is failing in my perf/core branch, please take a look. I'm

Please try applying this:

---
 Documentation/admin-guide/sysctl/kernel.rst | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 335696d3360d..aaa5bbcd1e33 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -709,7 +709,13 @@ perf_event_paranoid
 ===================
 
 Controls use of the performance events system by unprivileged
-users (without CAP_SYS_ADMIN).  The default value is 2.
+users (without CAP_PERFMON).  The default value is 2.
+
+For backward compatibility reasons access to system performance
+monitoring and observability remains open for CAP_SYS_ADMIN
+privileged processes but CAP_SYS_ADMIN usage for secure system
+performance monitoring and observability operations is discouraged
+with respect to CAP_PERFMON use cases.
 
 ===  ==================================================================
  -1  Allow use of (almost) all events by all users.
@@ -718,13 +724,13 @@ users (without CAP_SYS_ADMIN).  The default value is 2.
      ``CAP_IPC_LOCK``.
 
 >=0  Disallow ftrace function tracepoint by users without
-     ``CAP_SYS_ADMIN``.
+     ``CAP_PERFMON``.
 
-     Disallow raw tracepoint access by users without ``CAP_SYS_ADMIN``.
+     Disallow raw tracepoint access by users without ``CAP_PERFMON``.
 
->=1  Disallow CPU event access by users without ``CAP_SYS_ADMIN``.
+>=1  Disallow CPU event access by users without ``CAP_PERFMON``.
 
->=2  Disallow kernel profiling by users without ``CAP_SYS_ADMIN``.
+>=2  Disallow kernel profiling by users without ``CAP_PERFMON``.
 ===  ==================================================================
 
---

Thanks,
Alexey

> 
> Trying to reproduce right now. What kind of failure do you see?
> Please share some specifics so I could follow up properly.
> 
> Thanks,
> Alexey
> 
>> pushing my perf/core branch with this series applied, please check that
>> everything is ok, I'll do some testing now, but it all seems ok.
>>
>> Thanks,
>>
>> - Arnaldo
>>  
>>> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
>>> ---
>>>  Documentation/admin-guide/sysctl/kernel.rst | 16 +++++++++++-----
>>>  1 file changed, 11 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
>>> index def074807cee..b06ae9389809 100644
>>> --- a/Documentation/admin-guide/sysctl/kernel.rst
>>> +++ b/Documentation/admin-guide/sysctl/kernel.rst
>>> @@ -720,20 +720,26 @@ perf_event_paranoid:
>>>  ====================
>>>  
>>>  Controls use of the performance events system by unprivileged
>>> -users (without CAP_SYS_ADMIN).  The default value is 2.
>>> +users (without CAP_PERFMON). The default value is 2.
>>> +
>>> +For backward compatibility reasons access to system performance
>>> +monitoring and observability remains open for CAP_SYS_ADMIN
>>> +privileged processes but CAP_SYS_ADMIN usage for secure system
>>> +performance monitoring and observability operations is discouraged
>>> +with respect to CAP_PERFMON use cases.
>>>  
>>>  ===  ==================================================================
>>>   -1  Allow use of (almost) all events by all users
>>>  
>>>       Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
>>>  
>>> ->=0  Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN
>>> +>=0  Disallow ftrace function tracepoint by users without CAP_PERFMON
>>>  
>>> -     Disallow raw tracepoint access by users without CAP_SYS_ADMIN
>>> +     Disallow raw tracepoint access by users without CAP_PERFMON
>>>  
>>> ->=1  Disallow CPU event access by users without CAP_SYS_ADMIN
>>> +>=1  Disallow CPU event access by users without CAP_PERFMON
>>>  
>>> ->=2  Disallow kernel profiling by users without CAP_SYS_ADMIN
>>> +>=2  Disallow kernel profiling by users without CAP_PERFMON
>>>  ===  ==================================================================
>>>  
>>>  
>>> -- 
>>> 2.24.1
>>>
>>
