linux-kernel - Re: [PATCH v7 03/12] perf/core: open access to probes for CAP

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Message-ID: <alpine.LRH.2.21.2002190622300.10165@namei.org>
Date:   Wed, 19 Feb 2020 06:22:40 +1100 (AEDT)
From:   James Morris <jmorris@...ei.org>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>
cc:     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>,
        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>,
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        <linux-security-module@...r.kernel.org>,
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        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: Re: [PATCH v7 03/12] perf/core: open access to probes for CAP_PERFMON
 privileged process

On Mon, 17 Feb 2020, Alexey Budankov wrote:

> 
> Open access to monitoring via kprobes and uprobes and eBPF tracing 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.
> 
> perf kprobes and uprobes are used by ftrace and eBPF. perf probe uses
> ftrace to define new kprobe events, and those events are treated as
> tracepoint events. eBPF defines new probes via perf_event_open interface
> and then the probes are used in eBPF tracing.
> 
> 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 perf_events subsystem
> remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN
> usage for secure perf_events monitoring is discouraged with respect to
> CAP_PERFMON capability.
> 
> Signed-off-by: Alexey Budankov <alexey.budankov@...ux.intel.com>


Reviewed-by: James Morris <jamorris@...ux.microsoft.com>


-- 
James Morris
<jmorris@...ei.org>