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From: Alexey Budankov <alexey.budankov@linux.intel.com>
To: Jonatan Corbet <corbet@lwn.net>,
	Kees Cook <keescook@chromium.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Cc: Jann Horn <jannh@google.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Andi Kleen <ak@linux.intel.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
	"kernel-hardening@lists.openwall.com"
	<kernel-hardening@lists.openwall.com>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: [PATCH v3 3/4] perf-security: elaborate on perf_events/Perf privileged users
Date: Mon, 11 Feb 2019 16:44:55 +0300	[thread overview]
Message-ID: <52e8b9ee-795c-5e48-661b-0c1dc10ae3e1@linux.intel.com> (raw)
In-Reply-To: <784bbe0d-56c1-bd63-1879-b7db988e40c0@linux.intel.com>


Elaborate on possible perf_event/Perf privileged users groups
and document steps about creating such groups.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
 Documentation/admin-guide/perf-security.rst | 43 +++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/Documentation/admin-guide/perf-security.rst b/Documentation/admin-guide/perf-security.rst
index 8772d44a5912..dccbf2ec0c9e 100644
--- a/Documentation/admin-guide/perf-security.rst
+++ b/Documentation/admin-guide/perf-security.rst
@@ -73,6 +73,48 @@ enable capturing of additional data required for later performance analysis of
 monitored processes or a system. For example, CAP_SYSLOG capability permits
 reading kernel space memory addresses from /proc/kallsyms file.
 
+perf_events/Perf privileged users
+---------------------------------
+
+Mechanisms of capabilities, privileged capability-dumb files [6]_ and file system
+ACLs [10]_ can be used to create a dedicated group of perf_events/Perf privileged
+users who are permitted to execute performance monitoring without scope limits.
+The following steps can be taken to create such a group of privileged Perf users.
+
+1. Create perf_users group of privileged Perf users, assign perf_users group to
+   Perf tool executable and limit access to the executable for other users in the
+   system who are not in the perf_users group:
+
+::
+
+   # groupadd perf_users
+   # ls -alhF
+   -rwxr-xr-x  2 root root  11M Oct 19 15:12 perf
+   # chgrp perf_users perf
+   # ls -alhF
+   -rwxr-xr-x  2 root perf_users  11M Oct 19 15:12 perf
+   # chmod o-rwx perf
+   # ls -alhF
+   -rwxr-x---  2 root perf_users  11M Oct 19 15:12 perf
+
+2. Assign the required capabilities to the Perf tool executable file and enable
+   members of perf_users group with performance monitoring privileges [6]_ :
+
+::
+
+   # setcap "cap_sys_admin,cap_sys_ptrace,cap_syslog=ep" perf
+   # setcap -v "cap_sys_admin,cap_sys_ptrace,cap_syslog=ep" perf
+   perf: OK
+   # getcap perf
+   perf = cap_sys_ptrace,cap_sys_admin,cap_syslog+ep
+
+As a result, members of perf_users group are capable of conducting performance
+monitoring by using functionality of the configured Perf tool executable that,
+when executes, passes perf_events subsystem scope checks.
+
+This specific access control management is only available to superuser or root
+running processes with CAP_SETPCAP, CAP_SETFCAP [6]_ capabilities.
+
 perf_events/Perf unprivileged users
 -----------------------------------
 
@@ -162,6 +204,7 @@ Bibliography
 .. [7] `<http://man7.org/linux/man-pages/man2/ptrace.2.html>`_
 .. [8] `<https://en.wikipedia.org/wiki/Hardware_performance_counter>`_
 .. [9] `<https://en.wikipedia.org/wiki/Model-specific_register>`_
+.. [10] `<http://man7.org/linux/man-pages/man5/acl.5.html>`_
 .. [11] `<http://man7.org/linux/man-pages/man2/getrlimit.2.html>`_
 .. [12] `<http://man7.org/linux/man-pages/man5/limits.conf.5.html>`_

  parent reply	other threads:[~2019-02-11 13:44 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-11 13:32 [PATCH v3 0/3] admin-guide: extend perf-security with resource control, data categories and privileged users Alexey Budankov
2019-02-11 13:42 ` [PATCH v3 1/4] perf-security: document perf_events/Perf resource control Alexey Budankov
2019-02-11 13:43 ` [PATCH v3 2/4] perf-security: document collected perf_events/Perf data categories Alexey Budankov
2019-02-11 13:44 ` Alexey Budankov [this message]
2019-02-11 13:45 ` [PATCH v3 4/4] perf-security: wrap paragraphs on 72 columns Alexey Budankov
2019-02-11 14:58 ` Alexey Budankov
2019-02-17 23:14 ` [PATCH v3 0/3] admin-guide: extend perf-security with resource control, data categories and privileged users Jonathan Corbet
2019-02-18  8:56   ` Alexey Budankov

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