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From fb1bf29b909f8443aae0171e3b9c8bc369e0a641 Mon Sep 17 00:00:00 2001
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From: Eduardo Otubo <otubo@redhat.com>
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Date: Fri, 28 Sep 2018 07:56:36 +0100
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Subject: [PATCH 2/6] seccomp: use SIGSYS signal instead of killing the thread
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Eduardo Otubo <otubo@redhat.com>
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Message-id: <20180928075639.16746-3-otubo@redhat.com>
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Patchwork-id: 82314
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O-Subject: [RHEL-8 qemu-kvm PATCH 2/5] seccomp: use SIGSYS signal instead of killing the thread
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Bugzilla: 1618356
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RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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RH-Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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From: Marc-André Lureau <marcandre.lureau@redhat.com>
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commit 6f2231e9b0931e1998d9ed0c509adf7aedc02db2
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Author: Marc-André Lureau <marcandre.lureau@redhat.com>
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Date: Wed Aug 22 19:02:47 2018 +0200
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seccomp: use SIGSYS signal instead of killing the thread
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The seccomp action SCMP_ACT_KILL results in immediate termination of
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the thread that made the bad system call. However, qemu being
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multi-threaded, it keeps running. There is no easy way for parent
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process / management layer (libvirt) to know about that situation.
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Instead, the default SIGSYS handler when invoked with SCMP_ACT_TRAP
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will terminate the program and core dump.
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This may not be the most secure solution, but probably better than
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just killing the offending thread. SCMP_ACT_KILL_PROCESS has been
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added in Linux 4.14 to improve the situation, which I propose to use
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by default if available in the next patch.
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Related to:
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https://bugzilla.redhat.com/show_bug.cgi?id=1594456
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Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
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Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
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Acked-by: Eduardo Otubo <otubo@redhat.com>
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Signed-off-by: Eduardo Otubo <otubo@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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qemu-seccomp.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/qemu-seccomp.c b/qemu-seccomp.c
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index 845a333..b88fa05 100644
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--- a/qemu-seccomp.c
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+++ b/qemu-seccomp.c
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@@ -120,7 +120,7 @@ int seccomp_start(uint32_t seccomp_opts)
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continue;
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}
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- rc = seccomp_rule_add_array(ctx, SCMP_ACT_KILL, blacklist[i].num,
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+ rc = seccomp_rule_add_array(ctx, SCMP_ACT_TRAP, blacklist[i].num,
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blacklist[i].narg, blacklist[i].arg_cmp);
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if (rc < 0) {
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goto seccomp_return;
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--
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1.8.3.1
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