From fb1bf29b909f8443aae0171e3b9c8bc369e0a641 Mon Sep 17 00:00:00 2001 From: Eduardo Otubo Date: Fri, 28 Sep 2018 07:56:36 +0100 Subject: [PATCH 2/6] seccomp: use SIGSYS signal instead of killing the thread MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Eduardo Otubo 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 RH-Acked-by: Marc-André Lureau RH-Acked-by: Thomas Huth From: Marc-André Lureau commit 6f2231e9b0931e1998d9ed0c509adf7aedc02db2 Author: Marc-André Lureau 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 Reviewed-by: Daniel P. Berrangé Acked-by: Eduardo Otubo Signed-off-by: Eduardo Otubo Signed-off-by: Danilo C. L. de Paula --- 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