| Message ID | 5ac4b7aa-b640-d8a4-1926-cf612fada974@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | admin-guide: extend perf-security with resource control, data categories and privileged users | expand |
On Fri, 1 Feb 2019 10:30:58 +0300 Alexey Budankov <alexey.budankov@linux.intel.com> wrote: > 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 7da7fa459718..fe90f8952be9 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: > + > +:: > + > + # 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 Since we're giving basic sysadmin info here, we should probably say explicitly that this will block access to the perf binary to anybody who is not in the perf_users group. > +2. Assign required capabilities to the Perf tool executable file and enable Assign *the* required > + 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 Why the *emphasis* here? We prefer to minimize this kind of markup whenever possible. Thanks, jon
On 07.02.2019 3:01, Jonathan Corbet wrote: > On Fri, 1 Feb 2019 10:30:58 +0300 > Alexey Budankov <alexey.budankov@linux.intel.com> wrote: > >> 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 7da7fa459718..fe90f8952be9 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 user >> + >> +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: >> + >> +:: >> + >> + # 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 > > Since we're giving basic sysadmin info here, we should probably say > explicitly that this will block access to the perf binary to anybody who > is not in the perf_users group. We already say that above: "limit *access* to the executable for other users in the system". Let's have it this way then: "limit access to the executable for other users in the system who are not in the perf_users group". > >> +2. Assign required capabilities to the Perf tool executable file and enable > > Assign *the* required Accepted. > >> + 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 > > Why the *emphasis* here? We prefer to minimize this kind of markup > whenever possible. Avoided emphasis here and in the other places of this paragraph. > > Thanks, > > jon > Thanks, Alexey
diff --git a/Documentation/admin-guide/perf-security.rst b/Documentation/admin-guide/perf-security.rst index 7da7fa459718..fe90f8952be9 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: + +:: + + # 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 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 ----------------------------------- @@ -156,6 +198,7 @@ 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>`_
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(+)