Commit 6f2231e9 authored by Marc-André Lureau's avatar Marc-André Lureau Committed by Eduardo Otubo
Browse files

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: default avatarMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: default avatarDaniel P. Berrangé <berrange@redhat.com>
Acked-by: default avatarEduardo Otubo <otubo@redhat.com>
parent 3392fbee

qemu-seccomp.c

+1 −1
Original line number Diff line number Diff line
@@ -125,7 +125,7 @@ static 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;