Failed to mount folders in Linux guest. This is usually because
the "vboxsf" file system is not available. Please verify that
the guest additions are properly installed in the guest and
can work properly. The command attempted was:
mount -t vboxsf -o uid=`id -u vagrant`,gid=`getent group vagrant | cut -d: -f3` vagrant /vagrant
mount -t vboxsf -o uid=`id -u vagrant`,gid=`id -g vagrant` vagrant /vagrant
sudo /etc/init.d/vboxadd setup
/etc/init.d/vboxaddがないのでどうしょもなかった
sudo apt-get update
sudo apt-get install virtualbox-guest-x11
上記実行後にvagrantから再起動してディレクトリ共有できた。