2026-11-04

Ubuntu’s Rust sudo breaks compatibility with argument wildcards

A concrete sudoers portability trap for administrators moving to sudo-rs: argument wildcard rules accepted by standard sudo may be rejected or interpreted differently, changing what commands a policy actually permits.

Systems Security

Logged at IST: 2026-11-04 10:55 IST

What it is: Chris Siebenmann’s report of a sudoers compatibility difference between standard sudo and Ubuntu 26.04’s sudo-rs.

Gist: A long-standing rule uses -bp[acru] to permit a narrow set of Exim queue options. The author reports that standard sudo treats the bracket expression as a wildcard, while sudo-rs does not support wildcards inside command-line arguments, so the rule no longer permits the intended invocations. Ubuntu’s sudo-rs manpage confirms that argument wildcards are unsupported (with a limited exception for a final *). The practical lesson is to audit and test sudoers policies during migration rather than assuming syntax compatibility means behavioral compatibility.

Source read: https://utcc.utoronto.ca/~cks/space/blog/linux/Ubuntu2604RustSudoNotCompatible

Cross-check: https://manpages.ubuntu.com/manpages/stonking/man5/sudoers-rs.5.html, Ubuntu manpage for sudo-rs 0.2.14-1ubuntu4.1; explicitly documents the argument-wildcard limitation.

Newsletter angle: Rust reimplementations can preserve familiar configuration syntax while changing policy semantics; test real sudoers rules against the exact implementation and version you deploy.