A small Rust implementation of pam_motd, with support for overlays and dropins.
This shows how to write a simple pure-Rust PAM module to display a
"message of the day" (motd).
At the same time, this enhances pam_motd to support looking up
paths with different priorities and merging multiple snippets.
By default, the following paths are sourced in this order:
/etc/motd(file)/run/motd(file)/usr/lib/motd(file)/etc/motd.d/(snippets)/run/motd.d/(snippets)/usr/lib/motd.d/(snippets)
This project follows the systemd-style approach of overlaying
files and dropin snippets from multiple hierarchies (i.e. /usr/lib,
/run, and /etc).
It does not have any additional non-Rust runtime dependency, that is
it does not link against libpam.so on the target host.
This crate produces a shared object (librpam_motd.so) which can be
directly installed as a PAM module, as follows:
$ cargo build --release
$ sudo install -o root -g root -m 0644 -D -s -Z target/release/librpam_motd.so /lib/x86_64-linux-gnu/security/rpam_motd.so
Please note that PAM modules path differs across distribution, so the
/lib/x86_64-linux-gnu/security/ above may need to be adjusted to
match host setup.
Default configuration for this PAM module is available under config/rpam-sample.
A live-action demo of that is in the following asciinema recording:
This project is an early proof-of-concept, and it may expose some raw edges or unexpected behavior.