From 7b223e38603de3a75602e14914d26f9d4baf52eb Mon Sep 17 00:00:00 2001 From: Christian Ehrhardt Date: Wed, 9 Feb 2022 12:14:56 +0100 Subject: [PATCH 1/2] tools/virtiofsd: Add rseq syscall to the seccomp allowlist The virtiofsd currently crashes when used with glibc 2.35. That is due to the rseq system call being added to every thread creation [1][2]. [1]: https://www.efficios.com/blog/2019/02/08/linux-restartable-sequences/ [2]: https://sourceware.org/pipermail/libc-alpha/2022-February/136040.html This happens not at daemon start, but when a guest connects /usr/lib/qemu/virtiofsd -f --socket-path=/tmp/testvfsd -o sandbox=chroot \ -o source=/var/guests/j-virtiofs --socket-group=kvm virtio_session_mount: Waiting for vhost-user socket connection... # start ok, now guest will connect virtio_session_mount: Received vhost-user socket connection virtio_loop: Entry fv_queue_set_started: qidx=0 started=1 fv_queue_set_started: qidx=1 started=1 Bad system call (core dumped) We have to put rseq on the seccomp allowlist to avoid that the daemon is crashing in this case. Reported-by: Michael Hudson-Doyle Signed-off-by: Christian Ehrhardt Reviewed-by: Dr. David Alan Gilbert Message-id: 20220209111456.3328420-1-christian.ehrhardt@canonical.com [Moved rseq to its alphabetically ordered position in the seccomp allowlist. --Stefan] Signed-off-by: Stefan Hajnoczi --- tools/virtiofsd/passthrough_seccomp.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/virtiofsd/passthrough_seccomp.c b/tools/virtiofsd/passthrough_seccomp.c index a3ce9f898d..2bc0127b69 100644 --- a/tools/virtiofsd/passthrough_seccomp.c +++ b/tools/virtiofsd/passthrough_seccomp.c @@ -91,6 +91,9 @@ static const int syscall_allowlist[] = { SCMP_SYS(renameat2), SCMP_SYS(removexattr), SCMP_SYS(restart_syscall), +#ifdef __NR_rseq + SCMP_SYS(rseq), /* required since glibc 2.35 */ +#endif SCMP_SYS(rt_sigaction), SCMP_SYS(rt_sigprocmask), SCMP_SYS(rt_sigreturn), -- 2.35.1