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

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Date:   Mon, 21 Aug 2023 11:28:26 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc:     Song Liu <song@...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 Tue, 22 Aug 2023 00:19:55 +0900
Masami Hiramatsu (Google) <mhiramat@...nel.org> wrote:

> > 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.  
> 
> As Song said, CAP_PERFMON allows user to put a kprobe anywhere user specified,
> and it can run BPF program on it. This means it can access raw address
> information via registers. if so, CAP_PERFMON allows seeing the kernel map or
> equivalent information at this point.

I still don't like just giving it full kallsyms access.

I really do hate capabilities.

-- Steve