Expose the pubkey used for authentication

[nbraud]

Would it be possible to expose the pubkey the user was authenticated with?

I am considering writing a setgid program that authenticates the user (using PAM) before atomically modifying an authorized_keys file (in a location the user cannot otherwise write to) and it would be quite nice to check they aren't removing the key they used to authenticate (and potentially locking themselves out)

The most straightforward way to communicate that information would be through the PAM environment but pam-bindings does not seem to (currently) provide a binding for pam_setenv (and pam_getenv)

[nbraud]

I guess the alternative would be to implement the agent-auth logic within that program, either in an ad-hoc way, or exposing the necessary functionality from pam_rssh and using it as a normal Rust lib.