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Subject: [PATCH v1 1/2] doc/admin-guide: note credentials consolidation under
 CAP_PERFMON
From:   Alexey Budankov <alexey.budankov@linux.intel.com>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>
Cc:     Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "linux-security-module@vger.kernel.org" 
        <linux-security-module@vger.kernel.org>,
        "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
        linux-man@vger.kernel.org
References: <161a51d3-7cdf-f9ee-c438-42bb7404693e@linux.intel.com>
Organization: Intel Corp.
Message-ID: <2b1a92a1-84ce-5c70-837d-8ffe96849588@linux.intel.com>
Date:   Mon, 19 Oct 2020 20:16:49 +0300
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Add note that starting from Linux v5.9 CAP_PERFMON Linux capability
is enough to conduct performance monitoring and observability using
perf_events API.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
 Documentation/admin-guide/perf-security.rst | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/Documentation/admin-guide/perf-security.rst b/Documentation/admin-guide/perf-security.rst
index 1307b5274a0f..57a65e27eeb9 100644
--- a/Documentation/admin-guide/perf-security.rst
+++ b/Documentation/admin-guide/perf-security.rst
@@ -84,11 +84,14 @@ capabilities then providing the process with CAP_PERFMON capability singly
 is recommended as the preferred secure approach to resolve double access
 denial logging related to usage of performance monitoring and observability.
 
-Unprivileged processes using perf_events system call are also subject
-for PTRACE_MODE_READ_REALCREDS ptrace access mode check [7]_ , whose
-outcome determines whether monitoring is permitted. So unprivileged
-processes provided with CAP_SYS_PTRACE capability are effectively
-permitted to pass the check.
+Prior Linux v5.9 unprivileged processes using perf_events system call
+are also subject for PTRACE_MODE_READ_REALCREDS ptrace access mode check
+[7]_ , whose outcome determines whether monitoring is permitted.
+So unprivileged processes provided with CAP_SYS_PTRACE capability are
+effectively permitted to pass the check. Starting from Linux v5.9
+CAP_SYS_PTRACE capability is not required and CAP_PERFMON is enough to
+be provided for processes to make performance monitoring and observability
+operations.
 
 Other capabilities being granted to unprivileged processes can
 effectively enable capturing of additional data required for later
-- 
2.24.1