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From:   "Lubashev, Igor" <ilubashe@akamai.com>
To:     James Morris <jmorris@namei.org>
CC:     Serge Hallyn <serge@hallyn.com>,
        "linux-security-module@vger.kernel.org" 
        <linux-security-module@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [RFC PATCH 0/1] security: add SECURE_KEEP_FSUID to preserve
 fsuid/fsgid across execve
Thread-Topic: [RFC PATCH 0/1] security: add SECURE_KEEP_FSUID to preserve
 fsuid/fsgid across execve
Thread-Index: AQHVIkp2KrFaTjvuWkqWuYjnYmNLQ6aa7f2AgAD6xpCAAIJWAIAbwq2g
Date:   Wed, 3 Jul 2019 00:58:34 +0000
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> From: James Morris <jmorris@namei.org>  on Friday, June 14, 2019 11:54 PM=
:
> On Sat, 15 Jun 2019, Lubashev, Igor wrote:
>=20
> > Unfortunately, perf is using uid=3D=3D0 and euid=3D=3D0 as a "capabilit=
y bits".
> >
> >
> > In tools/perf/util/evsel.c:
> > 	static bool perf_event_can_profile_kernel(void)
> > 	{
> > 		return geteuid() =3D=3D 0 || perf_event_paranoid() =3D=3D -1;
> > 	}
> >
> > In tools/perf/util/symbol.c:
> > 	static bool symbol__read_kptr_restrict(void)
> > 	{
> > 	...
> > 		value =3D ((geteuid() !=3D 0) || (getuid() !=3D 0)) ?
> > 				(atoi(line) !=3D 0) :
> > 				(atoi(line) =3D=3D 2);
> > 	...
> > 	}
>=20
> These are bugs. They should be checking for CAP_SYS_ADMIN.

Thanks for the suggestion.

Actually, the former one should be checking CAP_SYS_ADMIN, while the latter=
 -- CAP_SYSLOG (see lib/vsprintf.c).

Just posted a patch to perf (http://lists.infradead.org/pipermail/linux-arm=
-kernel/2019-July/664552.html).

Thank you,

- Igor