Ansible FreeBSD Jail Connection Plugin: Jail escape via symlink following in put_file (host-side root mv)

Summary

Ansible FreeBSD Jail Connection Plugin is an Ansible connection plugin for FreeBSD Jails via jexec. Through version 1.3.0, the jailexec connection plugin's put_file resolved a transfer's destination to a path on the jail host ( + ) and ran mkdir -p and mv there as root on the host. Those commands follow symbolic links, and the path was operated on outside the jail, so a symlink existing inside the jail was followed by the host-side, root-privileged mv. A party controlling content inside a managed jail (the jail's root, or any process able to create a symlink in a directory an Ansible task later writes to) can therefore cause an arbitrary root-owned write on the host, outside the jail — a full jail escape. Arbitrary root-owned host writes are readily escalated to host compromise (e.g. cron, rc.d, authorized_keys). Preconditions for this vulnerability are that the operator runs a copy/template/fetch-style task (anything using put_file) against the jail, and the attacker can place a symlink inside the jail at or above the task's destination before the transfer runs. This issue has been fixed in version 2.0.0.