Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH v6 01/10] capabilities: introduce CAP_PERFMON to kernel
 and user space
To:     Stephen Smalley <sds@tycho.nsa.gov>,
        James Morris <jmorris@namei.org>,
        Serge Hallyn <serge@hallyn.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Ingo Molnar <mingo@redhat.com>,
        "joonas.lahtinen@linux.intel.com" <joonas.lahtinen@linux.intel.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Will Deacon <will@kernel.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>
Cc:     Andi Kleen <ak@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Stephane Eranian <eranian@google.com>,
        Igor Lubashev <ilubashe@akamai.com>,
        Jiri Olsa <jolsa@redhat.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>,
        "linux-security-module@vger.kernel.org" 
        <linux-security-module@vger.kernel.org>,
        "selinux@vger.kernel.org" <selinux@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        "linux-parisc@vger.kernel.org" <linux-parisc@vger.kernel.org>,
        oprofile-list@lists.sf.net
References: <576a6141-36d4-14c0-b395-8d195892b916@linux.intel.com>
 <a4c5da70-b6d1-b133-9b64-34e164834b03@linux.intel.com>
 <5be0f67c-17e2-7861-37f3-a0f8a82be8f0@tycho.nsa.gov>
 <1bcb4cb1-98c4-cc1a-b8e3-fd8a0e1e606f@linux.intel.com>
 <06cdca0e-65f2-b58d-a84e-5a1907aa9eb5@tycho.nsa.gov>
From:   Alexey Budankov <alexey.budankov@linux.intel.com>
Organization: Intel Corp.
Message-ID: <e5d8dc64-6573-21f5-80dd-64cfbf72e13f@linux.intel.com>
Date:   Thu, 6 Feb 2020 21:38:14 +0300
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101
 Thunderbird/68.4.2
MIME-Version: 1.0
In-Reply-To: <06cdca0e-65f2-b58d-a84e-5a1907aa9eb5@tycho.nsa.gov>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 06.02.2020 21:30, Stephen Smalley wrote:
> On 2/6/20 1:26 PM, Alexey Budankov wrote:
>>
>> On 06.02.2020 21:23, Stephen Smalley wrote:
>>> On 2/5/20 12:30 PM, Alexey Budankov wrote:
>>>>
>>>> Introduce CAP_PERFMON capability designed to secure system performance
>>>> monitoring and observability operations so that CAP_PERFMON would assist
>>>> CAP_SYS_ADMIN capability in its governing role for performance monitoring
>>>> and observability subsystems.
>>>>
>>>> CAP_PERFMON hardens system security and integrity during performance
>>>> monitoring and observability operations by decreasing attack surface that
>>>> is available to a CAP_SYS_ADMIN privileged process [2]. Providing the access
>>>> to system performance monitoring and observability operations under CAP_PERFMON
>>>> capability singly, without the rest of CAP_SYS_ADMIN credentials, excludes
>>>> chances to misuse the credentials and makes the operation more secure.
>>>> Thus, CAP_PERFMON implements the principal of least privilege for performance
>>>> monitoring and observability operations (POSIX IEEE 1003.1e: 2.2.2.39 principle
>>>> of least privilege: A security design principle that states that a process
>>>> or program be granted only those privileges (e.g., capabilities) necessary
>>>> to accomplish its legitimate function, and only for the time that such
>>>> privileges are actually required)
>>>>
>>>> CAP_PERFMON meets the demand to secure system performance monitoring and
>>>> observability operations for adoption in security sensitive, restricted,
>>>> multiuser production environments (e.g. HPC clusters, cloud and virtual compute
>>>> environments), where root or CAP_SYS_ADMIN credentials are not available to
>>>> mass users of a system, and securely unblocks accessibility of system performance monitoring and observability operations beyond root and CAP_SYS_ADMIN use cases.
>>>>
>>>> CAP_PERFMON takes over CAP_SYS_ADMIN credentials related to system performance
>>>> monitoring and observability operations and balances amount of CAP_SYS_ADMIN
>>>> credentials following the recommendations in the capabilities man page [1]
>>>> for CAP_SYS_ADMIN: "Note: this capability is overloaded; see Notes to kernel
>>>> developers, below." For backward compatibility reasons access to system
>>>> performance monitoring and observability subsystems of the kernel remains
>>>> open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN capability
>>>> usage for secure system performance monitoring and observability operations
>>>> is discouraged with respect to the designed CAP_PERFMON capability.
>>>>
>>>> Although the software running under CAP_PERFMON can not ensure avoidance
>>>> of related hardware issues, the software can still mitigate these issues
>>>> following the official hardware issues mitigation procedure [2]. The bugs
>>>> in the software itself can be fixed following the standard kernel development
>>>> process [3] to maintain and harden security of system performance monitoring
>>>> and observability operations.
>>>>
>>>> [1] http://man7.org/linux/man-pages/man7/capabilities.7.html
>>>> [2] https://www.kernel.org/doc/html/latest/process/embargoed-hardware-issues.html
>>>> [3] https://www.kernel.org/doc/html/latest/admin-guide/security-bugs.html
>>>>
>>>> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
>>>
>>> This will require a small update to the selinux-testsuite to correctly reflect the new capability requirements, but that's easy enough.
>>
>> Is the suite a part of the kernel sources or something else?
> 
> It is external,
> https://github.com/SELinuxProject/selinux-testsuite
> 
> I wasn't suggesting that your patch be blocked on updating the testsuite, just noting that it will need to be done.

Ok. Thanks!

~Alexey