linux-kernel - Re: [RFC PATCH v1 1/1] tracing/kprobe: Add multi-probe support for 'perf

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Message-ID: <20230821102943.758dca19@gandalf.local.home>
Date:   Mon, 21 Aug 2023 10:29:43 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Song Liu <song@...nel.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Francis Laniel <flaniel@...ux.microsoft.com>,
        linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v1 1/1] tracing/kprobe: Add multi-probe support for
 'perf_kprobe' PMU

On Sun, 20 Aug 2023 03:02:18 -0700
Song Liu <song@...nel.org> wrote:

> > For the "unique symbol" + offset, you don't need the kallsyms, but need to
> > access the System.map or vmlinux image. In this case, we don't need to expand
> > the CAP_PERFMON capabilities.  
> 
> I agree this is not needed in this case. But I wonder whether it makes sense
> to give CAP_PERFMON access to /proc/kallsyms. Will this change make
> CAP_PERFMON less secure?

I guess the question is, does CAP_PERFMON allow seeing where the kernel
mapped itself via some other means? If not, then no, I would nack this as
being a security hole.

-- Steve