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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)
(defun setuid (uid)
#+sbcl (sb-posix:setuid uid)
#-(or sbcl) (foreign-funcall "setuid" :unsigned-int uid :int))
(defun setgid (gid)
#+sbcl (sb-posix:setgid gid)
#-(or sbcl) (foreign-funcall "setgid" :unsigned-int uid :int))
(defclass setuid-connection (rehome-connection fork-connection) ())
(defmethod establish-connection ((type (eql :setuid)) remaining &key to)
(unless (and (lisp-connection-p) (zerop (foreign-funcall "geteuid" :int)))
(error "~&SETUIDing requires a Lisp image running as root"))
(informat 1 "~&SETUIDing to ~A" to)
(multiple-value-bind (match groups)
(re:scan-to-strings #?/uid=([0-9]+).+gid=([0-9]+)/ (run "id" to))
(unless match
(error "Could not determine UID and GID of ~A" to))
(let* ((uid (parse-integer (elt groups 0)))
(gid (parse-integer (elt groups 1)))
(home
;; tilde expansion is POSIX
(ensure-directory-pathname (stripln (run (strcat "echo ~" to)))))
(datadir
(ensure-directory-pathname
(stripln
;; su(1) is not POSIX but very likely to be present
;; TODO however, this use of su(1) uses a non-portable -c argument
(mrun
"su" to "-c"
"echo ${XDG_CACHE_HOME:-$HOME/.cache}/consfigurator/data/")))))
(continue-connection (make-instance 'setuid-connection
:datadir datadir
:connattrs `(:remote-uid ,uid
:remote-gid ,gid
:remote-user ,to
:remote-home ,home))
remaining))))
(defmethod post-fork ((connection setuid-connection))
(let ((uid (connection-connattr connection :remote-uid))
(gid (connection-connattr connection :remote-gid)))
(run-program (list "chown" "-R"
(format nil "~A:~A" uid gid)
(unix-namestring (slot-value connection 'datadir))))
(unless (zerop (setgid gid))
(error "setgid(2) failed!"))
(unless (zerop (setuid uid))
(error "setuid(2) failed!"))
(posix-login-environment
(connection-connattr connection :remote-user)
(connection-connattr connection :remote-home))))
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