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-rw-r--r--guix/least-authority.scm25
1 files changed, 23 insertions, 2 deletions
diff --git a/guix/least-authority.scm b/guix/least-authority.scm
index bfd7275e7c..3465fe9a48 100644
--- a/guix/least-authority.scm
+++ b/guix/least-authority.scm
@@ -1,5 +1,5 @@
;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2022 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2022-2023 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -41,6 +41,8 @@
(define* (least-authority-wrapper program
#:key (name "pola-wrapper")
+ (user #f)
+ (group #f)
(guest-uid 1000)
(guest-gid 1000)
(mappings '())
@@ -55,7 +57,11 @@ symbols; it runs with GUEST-UID and GUEST-GID. MAPPINGS is a list of
<file-system-mapping> records indicating directories mirrored inside the
execution environment of PROGRAM. DIRECTORY is the working directory of the
wrapped process. Each environment listed in PRESERVED-ENVIRONMENT-VARIABLES
-is preserved; other environment variables are erased."
+is preserved; other environment variables are erased.
+
+When USER and GROUP are set and NAMESPACES does not include 'user, change UIDs
+and GIDs to these prior to executing PROGRAM. This usually requires that the
+resulting wrapper be executed as root so it can call setgid(2) and setuid(2)."
(define code
(with-imported-modules (source-module-closure
'((gnu system file-systems)
@@ -113,6 +119,10 @@ is preserved; other environment variables are erased."
#$program signal)
(exit (+ 128 signal))))))
+ (define namespaces '#$namespaces)
+ (define host-group '#$group)
+ (define host-user '#$user)
+
;; Note: 'call-with-container' creates a sub-process that this one
;; waits for. This might seem suboptimal but unshare(2) isn't
;; really applicable: the process would still run in the same PID
@@ -123,6 +133,17 @@ is preserved; other environment variables are erased."
(lambda ()
(chdir #$directory)
(environ variables)
+
+ (unless (memq 'user namespaces)
+ ;; This process lives in its parent user namespace,
+ ;; presumably as root; now is the time to setgid/setuid if
+ ;; asked for it (the 'clone' call would fail with EPERM if we
+ ;; changed UIDs/GIDs beforehand).
+ (when host-group
+ (setgid (group:gid (getgr host-group))))
+ (when host-user
+ (setuid (passwd:uid (getpw host-user)))))
+
(apply execl #$program #$program (cdr (command-line))))
;; Don't assume PROGRAM can behave as an init process.