| Message ID | 1364314072-2474-5-git-send-email-stefanha@redhat.com |
|---|---|
| State | New |
| Headers | show |
Stefan Hajnoczi <stefanha@redhat.com> wrote: > When we receive a file descriptor over a UNIX domain socket the > O_NONBLOCK flag is preserved. Clear the O_NONBLOCK flag and rely on > QEMU file descriptor users like migration, SPICE, VNC, block layer, and > others to set non-blocking only when necessary. > > This change ensures we don't accidentally expose O_NONBLOCK in the QMP > API. QMP clients should not need to get the non-blocking state > "correct". > > A recent real-world example was when libvirt passed a non-blocking TCP > socket for migration where we expected a blocking socket. The source > QEMU produced a corrupted migration stream since its code did not cope > with non-blocking sockets. > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Acked-by: Juan Quintela <quintela@redhat.com>
On 03/26/2013 10:07 AM, Stefan Hajnoczi wrote: > When we receive a file descriptor over a UNIX domain socket the > O_NONBLOCK flag is preserved. Clear the O_NONBLOCK flag and rely on > QEMU file descriptor users like migration, SPICE, VNC, block layer, and > others to set non-blocking only when necessary. > > This change ensures we don't accidentally expose O_NONBLOCK in the QMP > API. QMP clients should not need to get the non-blocking state > "correct". > > A recent real-world example was when libvirt passed a non-blocking TCP > socket for migration where we expected a blocking socket. The source > QEMU produced a corrupted migration stream since its code did not cope > with non-blocking sockets. > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > --- > qemu-char.c | 3 +++ > 1 file changed, 3 insertions(+) Reviewed-by: Eric Blake <eblake@redhat.com> Covers both 'getfd' and 'add-fd' paths.
diff --git a/qemu-char.c b/qemu-char.c index 8fb8340..e50b1b3 100644 --- a/qemu-char.c +++ b/qemu-char.c @@ -2407,6 +2407,9 @@ static void unix_process_msgfd(CharDriverState *chr, struct msghdr *msg) if (fd < 0) continue; + /* O_NONBLOCK is preserved across SCM_RIGHTS so reset it */ + qemu_set_block(fd); + #ifndef MSG_CMSG_CLOEXEC qemu_set_cloexec(fd); #endif
When we receive a file descriptor over a UNIX domain socket the O_NONBLOCK flag is preserved. Clear the O_NONBLOCK flag and rely on QEMU file descriptor users like migration, SPICE, VNC, block layer, and others to set non-blocking only when necessary. This change ensures we don't accidentally expose O_NONBLOCK in the QMP API. QMP clients should not need to get the non-blocking state "correct". A recent real-world example was when libvirt passed a non-blocking TCP socket for migration where we expected a blocking socket. The source QEMU produced a corrupted migration stream since its code did not cope with non-blocking sockets. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- qemu-char.c | 3 +++ 1 file changed, 3 insertions(+)