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Subject: [PATCH v6 10/10] drivers/oprofile: open access for CAP_PERFMON
 privileged process
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>,
        "benh@kernel.crashing.org" <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        "james.bottomley@hansenpartnership.com" 
        <james.bottomley@hansenpartnership.com>,
        Serge Hallyn <serge@hallyn.com>, Will Deacon <will@kernel.org>,
        Robert Richter <rric@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>
Cc:     "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>,
        Jiri Olsa <jolsa@redhat.com>, Andi Kleen <ak@linux.intel.com>,
        Stephane Eranian <eranian@google.com>,
        Igor Lubashev <ilubashe@akamai.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Song Liu <songliubraving@fb.com>,
        Lionel Landwerlin <lionel.g.landwerlin@intel.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "linux-security-module@vger.kernel.org" 
        <linux-security-module@vger.kernel.org>,
        "selinux@vger.kernel.org" <selinux@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
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        "linux-perf-users@vger.kernel.org" <linux-perf-users@vger.kernel.org>,
        oprofile-list@lists.sf.net
References: <74d524ab-ac11-a7b8-1052-eba10f117e09@linux.intel.com>
Organization: Intel Corp.
Message-ID: <eff5e211-7114-f854-f53f-08491f9dcc26@linux.intel.com>
Date:   Tue, 28 Jan 2020 09:14:21 +0300
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Open access to monitoring for CAP_PERFMON privileged process. Providing
the access under CAP_PERFMON capability singly, without the rest of
CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials and
makes operation more secure.

CAP_PERFMON implements the principal of least privilege for performance
monitoring and observability operations (POSIX IEEE 1003.1e 2.2.2.39 principle
of least privilege: A security design principle that states that a process
or program be granted only those privileges (e.g., capabilities) necessary
to accomplish its legitimate function, and only for the time that such
privileges are actually required)

For backward compatibility reasons access to the monitoring remains open
for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage for secure
monitoring is discouraged with respect to CAP_PERFMON capability.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
 drivers/oprofile/event_buffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/oprofile/event_buffer.c b/drivers/oprofile/event_buffer.c
index 12ea4a4ad607..6c9edc8bbc95 100644
--- a/drivers/oprofile/event_buffer.c
+++ b/drivers/oprofile/event_buffer.c
@@ -113,7 +113,7 @@ static int event_buffer_open(struct inode *inode, struct file *file)
 {
 	int err = -EPERM;
 
-	if (!capable(CAP_SYS_ADMIN))
+	if (!perfmon_capable())
 		return -EPERM;
 
 	if (test_and_set_bit_lock(0, &buffer_opened))
-- 
2.20.1