From fb1bf29b909f8443aae0171e3b9c8bc369e0a641 Mon Sep 17 00:00:00 2001
From: Eduardo Otubo <otubo@redhat.com>
Date: Fri, 28 Sep 2018 07:56:36 +0100
Subject: [PATCH 2/6] seccomp: use SIGSYS signal instead of killing the thread
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RH-Author: Eduardo Otubo <otubo@redhat.com>
Message-id: <20180928075639.16746-3-otubo@redhat.com>
Patchwork-id: 82314
O-Subject: [RHEL-8 qemu-kvm PATCH 2/5] seccomp: use SIGSYS signal instead of killing the thread
Bugzilla: 1618356
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
RH-Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>
From: Marc-André Lureau <marcandre.lureau@redhat.com>
commit 6f2231e9b0931e1998d9ed0c509adf7aedc02db2
Author: Marc-André Lureau <marcandre.lureau@redhat.com>
Date: Wed Aug 22 19:02:47 2018 +0200
seccomp: use SIGSYS signal instead of killing the thread
The seccomp action SCMP_ACT_KILL results in immediate termination of
the thread that made the bad system call. However, qemu being
multi-threaded, it keeps running. There is no easy way for parent
process / management layer (libvirt) to know about that situation.
Instead, the default SIGSYS handler when invoked with SCMP_ACT_TRAP
will terminate the program and core dump.
This may not be the most secure solution, but probably better than
just killing the offending thread. SCMP_ACT_KILL_PROCESS has been
added in Linux 4.14 to improve the situation, which I propose to use
by default if available in the next patch.
Related to:
https://bugzilla.redhat.com/show_bug.cgi?id=1594456
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Eduardo Otubo <otubo@redhat.com>
Signed-off-by: Eduardo Otubo <otubo@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
qemu-seccomp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/qemu-seccomp.c b/qemu-seccomp.c
index 845a333..b88fa05 100644
--- a/qemu-seccomp.c
+++ b/qemu-seccomp.c
@@ -120,7 +120,7 @@ int seccomp_start(uint32_t seccomp_opts)
continue;
}
- rc = seccomp_rule_add_array(ctx, SCMP_ACT_KILL, blacklist[i].num,
+ rc = seccomp_rule_add_array(ctx, SCMP_ACT_TRAP, blacklist[i].num,
blacklist[i].narg, blacklist[i].arg_cmp);
if (rc < 0) {
goto seccomp_return;
--
1.8.3.1