perf-security: elaborate on perf_events/Perf privileged users (e152c7b7) · Commits · 戴 / test

Documentation/admin-guide/perf-security.rst

+43 −0

Original line number	Diff line number	Diff line
		@@ -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>`_

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