linux-kernel - [PATCH v7 06/12] trace/bpf_trace: open access for CAP

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Message-ID: <fc689865-f8ff-1e85-ac0c-b2f1c28b7eb6@linux.intel.com>
Date:   Mon, 17 Feb 2020 11:09:29 +0300
From:   Alexey Budankov <alexey.budankov@...ux.intel.com>
To:     James Morris <jmorris@...ei.org>, Serge Hallyn <serge@...lyn.com>,
        Stephen Smalley <sds@...ho.nsa.gov>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        "joonas.lahtinen@...ux.intel.com" <joonas.lahtinen@...ux.intel.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Will Deacon <will@...nel.org>,
        Paul Mackerras <paulus@...ba.org>,
        Helge Deller <deller@....de>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Andi Kleen <ak@...ux.intel.com>,
        Stephane Eranian <eranian@...gle.com>,
        Igor Lubashev <ilubashe@...mai.com>,
        Jiri Olsa <jolsa@...hat.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "selinux@...r.kernel.org" <selinux@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-parisc@...r.kernel.org" <linux-parisc@...r.kernel.org>,
        oprofile-list@...ts.sf.net,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        linux-man@...r.kernel.org
Subject: [PATCH v7 06/12] trace/bpf_trace: open access for CAP_PERFMON
 privileged process


Open access to bpf_trace 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 bpf_trace monitoring
remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN
usage for secure bpf_trace monitoring is discouraged with respect to
CAP_PERFMON capability.

Signed-off-by: Alexey Budankov <alexey.budankov@...ux.intel.com>
---
 kernel/trace/bpf_trace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 19e793aa441a..70e8249eebe5 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1416,7 +1416,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)
 	u32 *ids, prog_cnt, ids_len;
 	int ret;
 
-	if (!capable(CAP_SYS_ADMIN))
+	if (!perfmon_capable())
 		return -EPERM;
 	if (event->attr.type != PERF_TYPE_TRACEPOINT)
 		return -EINVAL;
-- 
2.20.1