:AS connection type uses :SU not :SUDO

Signed-off-by: Sean Whitton <spwhitton@spwhitton.name>

4 files changed, 51 insertions, 10 deletions

diff --git a/consfigurator.asd b/consfigurator.asd
index 856cb4e..c65813e 100644
--- a/consfigurator.asd
+++ b/consfigurator.asd
@@ -38,6 +38,7 @@
 	       (:file "src/connection/fork")
                (:file "src/connection/ssh")
                (:file "src/connection/sudo")
+               (:file "src/connection/su")
                (:file "src/connection/sbcl")
                (:file "src/connection/chroot")
                (:file "src/connection/chroot/fork")
diff --git a/src/connection/as.lisp b/src/connection/as.lisp
index b5a9f69..6f6edc6 100644
--- a/src/connection/as.lisp
+++ b/src/connection/as.lisp
@@ -24,13 +24,14 @@
   (zerop (foreign-funcall "geteuid" :int)))
 
 (defmethod establish-connection ((type (eql :as)) remaining &key to)
-  "Establish a :SETUID or :SUDO connection to another user account, depending
-on whether it is possible to establish a :SETUID connection.
-
-This connection type does not support sudo with a password -- it is designed
-to be used as root."
-  (if (and (lisp-connection-p)
-           (can-setuid)
-           (can-probably-fork))
-      (establish-connection :setuid remaining :to to)
-      (establish-connection :sudo remaining :user to)))
+  "Establish a :SETUID or :SU connection to another user account, depending on
+whether it is possible to establish a :SETUID connection.
+
+Note that both these connection types require root."
+  ;; An alternative to :SU would be :SUDO or runuser(1), but :SU is more
+  ;; portable.
+  (establish-connection (if (and (lisp-connection-p)
+                                 (can-setuid)
+                                 (can-probably-fork))
+                            :setuid :su)
+                        remaining :to to))
diff --git a/src/connection/su.lisp b/src/connection/su.lisp
new file mode 100644
index 0000000..444ece2
--- /dev/null
+++ b/src/connection/su.lisp
@@ -0,0 +1,34 @@
+;;; 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.su)
+(named-readtables:in-readtable :consfigurator)
+
+(defmethod establish-connection ((type (eql :su)) remaining &key to)
+  (declare (ignore remaining))
+  ;; We don't support using su with a password.  Use :SUDO for that.
+  (assert-euid-root)
+  (informat 1 "~&Switching to user ~A" to)
+  (make-instance 'su-connection :user to))
+
+(defclass su-connection (shell-wrap-connection)
+  ((user :initarg :user)))
+
+(defmethod connection-shell-wrap ((connection su-connection) cmd)
+  (format nil "su ~A -c ~A"
+          (escape-sh-token (slot-value connection 'user))
+          (escape-sh-token cmd)))
diff --git a/src/package.lisp b/src/package.lisp
index 014840b..76d1802 100644
--- a/src/package.lisp
+++ b/src/package.lisp
@@ -322,6 +322,11 @@
         #:alexandria
         #:consfigurator.connection.shell-wrap))
 
+(defpackage :consfigurator.connection.su
+  (:use #:cl
+        #:consfigurator
+        #:consfigurator.connection.shell-wrap))
+
 (defpackage :consfigurator.connection.local
   (:use #:cl #:consfigurator #:alexandria)
   (:export #:local-connection))