From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34649) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZgrO7-0006xw-Fy for qemu-devel@nongnu.org; Tue, 29 Sep 2015 05:40:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZgrO3-0001aq-3M for qemu-devel@nongnu.org; Tue, 29 Sep 2015 05:39:55 -0400 Received: from mail-wi0-f170.google.com ([209.85.212.170]:35811) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZgrO2-0001aK-Mc for qemu-devel@nongnu.org; Tue, 29 Sep 2015 05:39:50 -0400 Received: by wicge5 with SMTP id ge5so141711842wic.0 for ; Tue, 29 Sep 2015 02:39:49 -0700 (PDT) Date: Tue, 29 Sep 2015 11:39:46 +0200 From: Eduardo Otubo Message-ID: <20150929093946.GA30238@vader> References: <1435756353-4150-1-git-send-email-drjones@redhat.com> <20150924093119.GA11859@vader> <20150924135004.GC3486@hawk.localdomain> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="BOKacYhQ+x31HxR3" Content-Disposition: inline In-Reply-To: <20150924135004.GC3486@hawk.localdomain> Subject: Re: [Qemu-devel] [PATCH] libseccomp: add cacheflush to whitelist List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Andrew Jones Cc: pmoore@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org --BOKacYhQ+x31HxR3 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Sep 24, 2015 at 03=3D50=3D04PM +0200, Andrew Jones wrote: > On Thu, Sep 24, 2015 at 11:31:19AM +0200, Eduardo Otubo wrote: > > On Wed, Jul 01, 2015 at 09=3D12=3D33AM -0400, Andrew Jones wrote: > > > cacheflush is an arm-specific syscall that qemu built for arm > > > uses. Add it to the whitelist. > > >=20 > > > Signed-off-by: Andrew Jones > > >=20 > > > --- > > >=20 > > > I'm not sure about the priority selection. Maybe cacheflush gets > > > used frequently enough that it deserves a higher one? > >=20 > > The frequency is measured using strace and comparing the frequency they > > appear among other syscalls. Can you run this analysis and double check > > if the lowest priority is still accurate? >=20 > Hi Eduardo, >=20 > Short answer: The lowest priority is definitely correct. >=20 > Long answer: >=20 > I ran strace while installing a new guest, of 3.6 million syscalls, > only 5 were cacheflush. Of course the syscalls used (and their frequency) > is host-type, qemu machine-type, config (qemu command line), and guest > workload specific. So, ideally, qemu machine-types would register their > own whitelists, possibly modified by host-type. For example, I ran the > mach-virt machine-type on both a midway and a mustang. In both cases it > was a basic guest config and an install-type workload. For the mustang, > over 55% of the syscalls were ioctl, but, for the midway, ioctls were > 16% and 43% were clock_gettime. I generated a most-used-first list for > each. Neither list really matched up well with seccomp_whitelist (except > for futex). >=20 > Besides allowing machine types to help set priorities, it may also be > nice if both compile-time and run-time configs could further reduce the > whitelist. For example, mlockall is only necessary if '-realtime mlock=3D= on' > is passed on the command line. >=20 > Thanks, > drew >=20 > >=20 > > Thanks for the patch. > >=20 > > >=20 > > > This patch isn't really necessary yet due to ae6e8ef11e6c: "Revert > > > seccomp tests that allow it to be used on non-x86 architectures", > > > which we can't revert until libseccomp has released a fix for > > > arm-specific syscall symbol naming, but when linking to a patched > > > libseccomp and reverting ae6e8ef11e6c, then this patch allows > > > guests to boot with '-sandbox on'. > > >=20 > > > Signed-off-by: Andrew Jones > > > --- > > > qemu-seccomp.c | 3 ++- > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > >=20 > > > diff --git a/qemu-seccomp.c b/qemu-seccomp.c > > > index f9de0d3390feb..33644a4e3c3d3 100644 > > > --- a/qemu-seccomp.c > > > +++ b/qemu-seccomp.c > > > @@ -237,7 +237,8 @@ static const struct QemuSeccompSyscall seccomp_wh= itelist[] =3D { > > > { SCMP_SYS(fadvise64), 240 }, > > > { SCMP_SYS(inotify_init1), 240 }, > > > { SCMP_SYS(inotify_add_watch), 240 }, > > > - { SCMP_SYS(mbind), 240 } > > > + { SCMP_SYS(mbind), 240 }, > > > + { SCMP_SYS(cacheflush), 240 }, > > > }; > > > =20 > > > int seccomp_start(void) > > > --=20 > > > 2.1.0 > > >=20 Acked-by: Eduardo Otubo --=20 Eduardo Otubo ProfitBricks GmbH --BOKacYhQ+x31HxR3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJWClxiAAoJEP0M/1sS+L0v5WQIAIoCkPR0YQ2l3pVeDwwOmB2z GyB491sOUHhbdhVj1Vms0l4D/5puzkKTER5tb9m0GJvHh5/AaOTls6/N+qK1x00r nQyO6d465B+xtKMk+/92ui/8pZCZTjCGNd3JBRQmVaNSJtOxp609N/zXJa6fHCil sJX/JVIaTl/wBLQYCppEDP7fZdk3cq3TkJWF705oFe7e9Ka2CEpLOcaGQRGhCuhg dNY2XiRtoRDw4B8FIRIVJKGLu0s9IDZ+3kPUjebDhhGJcm61OICEf24IB1kjd5At L12lKr+lgG/Z7bbtY8m/L+uoXpE5B1llPUAb0y+gYlhqAnsXb4/8SYKJEaiDp8w= =ueD8 -----END PGP SIGNATURE----- --BOKacYhQ+x31HxR3--