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Subject: [PATCH v1 2/3] perf/core: apply CAP_SYS_PERFMON to CPUs and kernel
 monitoring
From:   Alexey Budankov <alexey.budankov@linux.intel.com>
To:     Peter Zijlstra <peterz@infradead.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Ingo Molnar <mingo@redhat.com>
Cc:     Jiri Olsa <jolsa@redhat.com>, Andi Kleen <ak@linux.intel.com>,
        elena.reshetova@intel.com,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jann Horn <jannh@google.com>,
        Kees Cook <keescook@chromium.org>,
        Stephane Eranian <eranian@google.com>,
        Namhyung Kim <namhyung@kernel.org>,
        linux-security-module@vger.kernel.org, selinux@vger.kernel.org,
        linux-kernel <linux-kernel@vger.kernel.org>
References: <283f09a5-33bd-eac3-bdfd-83d775045bf9@linux.intel.com>
Organization: Intel Corp.
Message-ID: <fdd428a9-1906-410c-99b0-c9568a72f320@linux.intel.com>
Date:   Thu, 5 Dec 2019 19:21:32 +0300
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Enable CAP_SYS_PERFMON privileged process with secure performance monitoring
of available online CPUs, when executing code in kernel and user modes.

For backward compatibility reasons performance monitoring functionality of 
perf_events subsystem remains available under CAP_SYS_ADMIN but its usage for
secure performance monitoring use cases is discouraged with respect to the
introduced CAP_SYS_PERFMON capability.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
 include/linux/perf_event.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 34c7c6910026..e8dc8411de9a 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1285,7 +1285,8 @@ static inline int perf_is_paranoid(void)
 
 static inline int perf_allow_kernel(struct perf_event_attr *attr)
 {
-	if (sysctl_perf_event_paranoid > 1 && !capable(CAP_SYS_ADMIN))
+	if (sysctl_perf_event_paranoid > 1 &&
+	   !(capable(CAP_SYS_PERFMON) || capable(CAP_SYS_ADMIN)))
 		return -EACCES;
 
 	return security_perf_event_open(attr, PERF_SECURITY_KERNEL);
@@ -1293,7 +1294,8 @@ static inline int perf_allow_kernel(struct perf_event_attr *attr)
 
 static inline int perf_allow_cpu(struct perf_event_attr *attr)
 {
-	if (sysctl_perf_event_paranoid > 0 && !capable(CAP_SYS_ADMIN))
+	if (sysctl_perf_event_paranoid > 0 &&
+	    !(capable(CAP_SYS_PERFMON) || capable(CAP_SYS_ADMIN)))
 		return -EACCES;
 
 	return security_perf_event_open(attr, PERF_SECURITY_CPU);
-- 
2.20.1