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Re: [Qemu-devel] [PATCH] seccomp: allow sched_setscheduler() with SCHED_
From: |
Daniel P . Berrangé |
Subject: |
Re: [Qemu-devel] [PATCH] seccomp: allow sched_setscheduler() with SCHED_IDLE policy |
Date: |
Mon, 16 Jul 2018 10:35:32 +0100 |
User-agent: |
Mutt/1.10.0 (2018-05-17) |
On Wed, Jul 11, 2018 at 04:48:55PM +0200, Eduardo Otubo wrote:
> On 10/07/2018 - 16:55:57, Marc-André Lureau wrote:
> > Current and upcoming mesa releases rely on a shader disk cash. It uses
> > a thread job queue with low priority, set with
> > sched_setscheduler(SCHED_IDLE). However, that syscall is rejected by
> > the "resourcecontrol" seccomp qemu filter.
> >
> > Since it should be safe to allow lowering thread priority, let's allow
> > scheduling thread to idle policy.
> >
> > Related to:
> > https://bugzilla.redhat.com/show_bug.cgi?id=1594456
> >
> > Signed-off-by: Marc-André Lureau <address@hidden>
> > ---
> > qemu-seccomp.c | 12 ++++++++++--
> > 1 file changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/qemu-seccomp.c b/qemu-seccomp.c
> > index 148e4c6f24..9cd8eb9499 100644
> > --- a/qemu-seccomp.c
> > +++ b/qemu-seccomp.c
> > @@ -34,6 +34,12 @@
> > struct QemuSeccompSyscall {
> > int32_t num;
> > uint8_t set;
> > + uint8_t narg;
> > + const struct scmp_arg_cmp *arg_cmp;
> > +};
> > +
> > +const struct scmp_arg_cmp sched_setscheduler_arg[] = {
> > + SCMP_A1(SCMP_CMP_NE, SCHED_IDLE)
> > };
> >
> > static const struct QemuSeccompSyscall blacklist[] = {
> > @@ -92,7 +98,8 @@ static const struct QemuSeccompSyscall blacklist[] = {
> > { SCMP_SYS(setpriority), QEMU_SECCOMP_SET_RESOURCECTL },
> > { SCMP_SYS(sched_setparam), QEMU_SECCOMP_SET_RESOURCECTL },
> > { SCMP_SYS(sched_getparam), QEMU_SECCOMP_SET_RESOURCECTL },
> > - { SCMP_SYS(sched_setscheduler), QEMU_SECCOMP_SET_RESOURCECTL },
> > + { SCMP_SYS(sched_setscheduler), QEMU_SECCOMP_SET_RESOURCECTL,
> > + ARRAY_SIZE(sched_setscheduler_arg), sched_setscheduler_arg },
> > { SCMP_SYS(sched_getscheduler), QEMU_SECCOMP_SET_RESOURCECTL },
> > { SCMP_SYS(sched_setaffinity), QEMU_SECCOMP_SET_RESOURCECTL },
> > { SCMP_SYS(sched_getaffinity), QEMU_SECCOMP_SET_RESOURCECTL },
> > @@ -118,7 +125,8 @@ static int seccomp_start(uint32_t seccomp_opts)
> > continue;
> > }
> >
> > - rc = seccomp_rule_add(ctx, SCMP_ACT_KILL, blacklist[i].num, 0);
> > + rc = seccomp_rule_add_array(ctx, SCMP_ACT_KILL, blacklist[i].num,
> > + blacklist[i].narg,
> > blacklist[i].arg_cmp);
> > if (rc < 0) {
> > goto seccomp_return;
> > }
> > --
> > 2.18.0.129.ge3331758f1
> >
>
> Acked-by: Eduardo Otubo <address@hidden>
>
> Patch looks safe enough for me. If everyone else is OK with this I'll send a
> pull-request tomorrow morning.
Reviewed-by: Daniel P. Berrangé <address@hidden>
Regards,
Daniel
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