[Virtio-fs] [PATCH] virtiofsd: Add clock_gettime() to seccomp white list

[Virtio-fs] [PATCH] virtiofsd: Add clock_gettime() to seccomp white list

[Masayoshi Mizuma]

From: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>

virtiofsd receives SIGSYS signal while qemu is shutting down.

  ]# ./virtiofsd -d -o vhost_user_socket=/tmp/vhostqemu0 \
     -o source=/tmp/share0 -o cache=auto
  ...
  virtio_send_msg: elem 0: with 1 in desc of length 16
  virtio_loop: Got VU event
  fv_queue_set_started: qidx=0 started=0
  fv_queue_thread: kill event on queue 0 - quitting
  fv_remove_watch: TODO! fd=9
  virtio_loop: Waiting for VU event
  Bad system call (core dumped)
  ]#

That is because virtiofsd calls clock_gettime() via glib
function and clock_gettime() isn't in seccomp white list,
so virtiofsd receives SIGSYS.
The glib function is called to manage the pool thread.
The calltrace is like as:

  #0  clock_gettime ()
  #1  g_get_monotonic_time ()
  #2  g_async_queue_timeout_pop ()
  #3  g_thread_pool_wait_for_new_pool ()
  #4  g_thread_pool_thread_proxy ()
  #5  g_thread_proxy ()
  #6  start_thread ()
  #7  clone ()

Add clock_gettime() to seccomp white list.

Signed-off-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
---
 contrib/virtiofsd/seccomp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/contrib/virtiofsd/seccomp.c b/contrib/virtiofsd/seccomp.c
index f815ea5bf9..b78056b13f 100644
--- a/contrib/virtiofsd/seccomp.c
+++ b/contrib/virtiofsd/seccomp.c
@@ -19,6 +19,7 @@ static const int syscall_whitelist[] = {
     SCMP_SYS(brk),
     SCMP_SYS(capget), /* For CAP_FSETID */
     SCMP_SYS(capset),
+    SCMP_SYS(clock_gettime),
     SCMP_SYS(clone),
     SCMP_SYS(close),
     SCMP_SYS(copy_file_range),
-- 
2.18.1

Re: [Virtio-fs] [PATCH] virtiofsd: Add clock_gettime() to seccomp white list

[Dr. David Alan Gilbert]

* Masayoshi Mizuma (msys.mizuma@gmail.com) wrote:
> From: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
> 
> virtiofsd receives SIGSYS signal while qemu is shutting down.
> 
>   ]# ./virtiofsd -d -o vhost_user_socket=/tmp/vhostqemu0 \
>      -o source=/tmp/share0 -o cache=auto
>   ...
>   virtio_send_msg: elem 0: with 1 in desc of length 16
>   virtio_loop: Got VU event
>   fv_queue_set_started: qidx=0 started=0
>   fv_queue_thread: kill event on queue 0 - quitting
>   fv_remove_watch: TODO! fd=9
>   virtio_loop: Waiting for VU event
>   Bad system call (core dumped)
>   ]#
> 
> That is because virtiofsd calls clock_gettime() via glib
> function and clock_gettime() isn't in seccomp white list,
> so virtiofsd receives SIGSYS.
> The glib function is called to manage the pool thread.
> The calltrace is like as:
> 
>   #0  clock_gettime ()
>   #1  g_get_monotonic_time ()
>   #2  g_async_queue_timeout_pop ()
>   #3  g_thread_pool_wait_for_new_pool ()
>   #4  g_thread_pool_thread_proxy ()
>   #5  g_thread_proxy ()
>   #6  start_thread ()
>   #7  clone ()
> 
> Add clock_gettime() to seccomp white list.
> 
> Signed-off-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>

Thanks; merged into the existing whitelist.

(And pushed to -dev - although the -dev world; which is in the middle
of a tidyup)

Dave

> ---
>  contrib/virtiofsd/seccomp.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/contrib/virtiofsd/seccomp.c b/contrib/virtiofsd/seccomp.c
> index f815ea5bf9..b78056b13f 100644
> --- a/contrib/virtiofsd/seccomp.c
> +++ b/contrib/virtiofsd/seccomp.c
> @@ -19,6 +19,7 @@ static const int syscall_whitelist[] = {
>      SCMP_SYS(brk),
>      SCMP_SYS(capget), /* For CAP_FSETID */
>      SCMP_SYS(capset),
> +    SCMP_SYS(clock_gettime),
>      SCMP_SYS(clone),
>      SCMP_SYS(close),
>      SCMP_SYS(copy_file_range),
> -- 
> 2.18.1
> 
> _______________________________________________
> Virtio-fs mailing list
> Virtio-fs@redhat.com
> https://www.redhat.com/mailman/listinfo/virtio-fs
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK