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;;; Consfigurator -- Lisp declarative configuration management system
;;; Copyright (C) 2021 Sean Whitton <spwhitton@spwhitton.name>
;;; This file is free software; you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3, or (at your option)
;;; any later version.
;;; This file is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;; You should have received a copy of the GNU General Public License
;;; along with this program. If not, see <http://www.gnu.org/licenses/>.
(in-package :consfigurator.connection.setuid)
(named-readtables:in-readtable :consfigurator)
(defclass setuid-connection (rehome-connection fork-connection) ())
(defmethod establish-connection ((type (eql :setuid)) remaining &key user)
(unless (and (lisp-connection-p) (zerop (nix:geteuid)))
(error "~&SETUIDing requires a Lisp image running as root"))
(informat 1 "~&SETUIDing to ~A" user)
(let* ((ent
(or (user:user-info user)
(failed-change "~&Could not look up user info for ~A." user)))
(xdg-cache-home
(ensure-directory-pathname
(stripln
;; su(1) is not POSIX but very likely to be present. Note that
;; the -c argument here is to the user's login shell, not the -c
;; argument to su(1) on, e.g., FreeBSD. So should be fairly
;; portable.
(mrun "su" (cdr (assoc :name ent))
"-c" "echo ${XDG_CACHE_HOME:-$HOME/.cache}"))))
(cache (merge-pathnames "consfigurator/" xdg-cache-home))
(datadir (merge-pathnames "data/" cache)))
(dolist (dir (list xdg-cache-home cache datadir))
(unless (directory-exists-p dir)
(nix:chown (ensure-directories-exist dir)
(cdr (assoc :user-id ent)) (cdr (assoc :group-id ent)))))
(continue-connection
(make-instance
'setuid-connection
:rehome-datadir datadir
:connattrs `(:remote-uid ,(cdr (assoc :user-id ent))
:remote-gid ,(cdr (assoc :group-id ent))
:remote-user ,(cdr (assoc :name ent))
:remote-home ,(ensure-directory-pathname
(cdr (assoc :home ent)))
:consfigurator-cache ,cache
:XDG_CACHE_HOME ,xdg-cache-home))
remaining)))
(defmethod post-fork ((connection setuid-connection))
(let ((uid (connection-connattr connection :remote-uid))
(gid (connection-connattr connection :remote-gid))
(user (connection-connattr connection :remote-user)))
(run-program
(list "chown" "-R"
(format nil "~A:~A" uid gid)
(unix-namestring (slot-value connection 'rehome-datadir))))
(posix-login-environment
uid user (connection-connattr connection :remote-home))
;; We are privileged, so this sets the real, effective and saved IDs.
(nix:setgid gid) (nix:initgroups user gid) (nix:setuid uid)))
(defmethod propagate-connattr
((type (eql :no-services)) connattr (connection setuid-connection))
connattr)
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