Re: [PATCH v3 2/3] perf tool: make Perf tool aware of SELinux access control

[Alexey Budankov]

On 18.05.2020 19:43, Alexey Budankov wrote:
> 
> On 18.05.2020 18:58, Arnaldo Carvalho de Melo wrote:
>> Em Thu, Apr 30, 2020 at 10:15:57AM +0300, Alexey Budankov escreveu:
>>>
>>> Implement selinux sysfs check to see the system is in enforcing
>>> mode and print warning message with pointer to check audit logs.
>>
>> There were some changes in this area meanwhile, so I had to apply the
>> evsel.c by hand, when I push this please double check everything is ok,
> 
> Will do. I appreciate your integrating effort.

Checked at tmp.perf/core branch. The message looks like this:

[root@nntvtune39 acme.tmp]# tools/perf/perf stat
Error:
Access to performance monitoring and observability operations is limited.
Enforced MAC policy settings (SELinux) can limit access to performance
monitoring and observability operations. Inspect system audit records for
more perf_event access control information and adjusting the policy.
Consider adjusting /proc/sys/kernel/perf_event_paranoid setting to open
access to performance monitoring and observability operations for users
without CAP_PERFMON or CAP_SYS_ADMIN Linux capability.
perf_event_paranoid setting is 2:
  -1: Allow use of (almost) all events by all users
      Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
>= 0: Disallow raw and ftrace function tracepoint access
>= 1: Disallow CPU event access
>= 2: Disallow kernel profiling
To make the adjusted perf_event_paranoid setting permanent preserve it
in /etc/sysctl.conf (e.g. kernel.perf_event_paranoid = <setting>)

Edited patch at security.txt didn't apply cleanly. It requires white space
prior tab in the first block for wake_alarm etc till perfmon:

---8<---
diff -Nura a/policy/flask/access_vectors b/policy/flask/access_vectors
--- a/policy/flask/access_vectors	2020-02-04 18:19:53.000000000 +0300
+++ b/policy/flask/access_vectors	2020-02-28 23:37:25.000000000 +0300
@@ -174,6 +174,7 @@
 	wake_alarm
 	block_suspend
 	audit_read
+	perfmon
 }

 #
@@ -1099,3 +1100,15 @@

 class xdp_socket
 inherits socket
+
+class perf_event
+{
+	open
+	cpu
+	kernel
+	tracepoint
+	read
+	write
+}
+
+
diff -Nura a/policy/flask/security_classes b/policy/flask/security_classes
--- a/policy/flask/security_classes	2020-02-04 18:19:53.000000000 +0300
+++ b/policy/flask/security_classes	2020-02-28 21:35:17.000000000 +0300
@@ -200,4 +200,6 @@

 class xdp_socket

+class perf_event
+
 # FLASK

---8<---

~Alexey