Date: Mon, 26 Nov 2018 13:28:33 -0700 From: Jonathan Corbet <corbet@....net> To: Alexey Budankov <alexey.budankov@...ux.intel.com> Cc: Thomas Gleixner <tglx@...utronix.de>, Kees Cook <keescook@...omium.org>, Jann Horn <jannh@...gle.com>, Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, Arnaldo Carvalho de Melo <acme@...nel.org>, Andi Kleen <ak@...ux.intel.com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>, Tvrtko Ursulin <tursulin@...ulin.net>, linux-kernel <linux-kernel@...r.kernel.org>, "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org> Subject: Re: [PATCH v2 1/2] Documentation/admin-guide: introduce perf-security.rst file On Mon, 26 Nov 2018 11:57:21 +0300 Alexey Budankov <alexey.budankov@...ux.intel.com> wrote: > >> +For the purpose of performing security checks Linux implementation splits > >> +processes into two categories _ : a) privileged processes (whose effective > >> +user ID is 0, referred to as superuser or root), and b) unprivileged processes > >> +(whose effective UID is nonzero). > > > > Is that really what's going on here? If I understand things correctly, > > it's looking for CAP_SYS_PTRACE rather than a specific UID; am I missing > > something here? > > You are right regarding CAP_SYS_PTRACE but this capability is not the only > one which is used by perf_events for security checks, so the capabilities > clarification is kept aside of these patches, because patches initial intention > is to clarify security specifics of sysctl_perf_even_paranoid settings. > > I agree that the document can be extended with details clarifying capabilities > used by perf_events for security checks. I don't really like the idea of adding a document that we know doesn't really describe how the security decision is made. Even a one-line parenthetical saying that things are more complicated and giving a pointer to a place to look for details would help, IMO. Either way, I can merge this, but I'd like to have an ack from the perf folks first. Thanks, jon
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