[bug#70341] [PATCH v2] services: tor: Add support for pluggable transports.

[Nigko Yerden <nigko.yerden@gmail.com>]

Pluggable transports are programs that disguise Tor traffic, which
can be useful in cases when Tor is censored.  Pluggable transports
cannot be configured by #:config-file file exclusively because Tor
process is run via 'least-authority-wrapper' and cannot have access
to transport plugin, which is a separate executable (Bug:#70302,
Bug:#70332).

* doc/guix.texi (Networking Services): Document 'transport-plugin' and
'pluggable-transport' options for 'tor-configuration'.
* gnu/services/networking.scm (<tor-configuration>): Add 'transport-plugin'
and 'pluggable-transport' fields.
(tor-configuration->torrc)[transport-plugin]: Add content to 'torrc'
computed-file.
(tor-shepherd-service)[transport-plugin-path]: Add file-system-mapping.

Change-Id: I64e7632729287ea0ab27818bb7322fddae43de48
---
 doc/guix.texi               | 11 ++++++++
 gnu/services/networking.scm | 52 +++++++++++++++++++++++++------------
 2 files changed, 47 insertions(+), 16 deletions(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index 65af136e61..9fbe928484 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -127,6 +127,7 @@
 Copyright @copyright{} 2024 Herman Rimm@*
 Copyright @copyright{} 2024 Matthew Trzcinski@*
 Copyright @copyright{} 2024 Richard Sent@*
+Copyright @copyright{} 2024 Nigko Yerden@*
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3 or
@@ -21849,6 +21850,16 @@ Networking Services
 @file{/var/run/tor/control-sock}, which will be made writable by members of the
 @code{tor} group.
 
+@item @code{transport-plugin} (default: @code{#f})
+This must be either @code{#f}, in which case the pluggable transports are
+not used by Tor, or a ``file-like'' object pointing to the pluggable transport
+plugin executable.  In the latter case the @code{#:config-file} file
+should contain line(s) configuring one or more bridges.
+
+@item @code{pluggable-transport} (default: @code{"obfs4"})
+A string that specifies the type of the pluggable transport in
+case @code{#:transport-plugin} is not @code{#f}.
+
 @end table
 @end deftp
 
diff --git a/gnu/services/networking.scm b/gnu/services/networking.scm
index 8e64e529ab..e47f7ca61a 100644
--- a/gnu/services/networking.scm
+++ b/gnu/services/networking.scm
@@ -22,6 +22,7 @@
 ;;; Copyright © 2023 Declan Tsien <declantsien@riseup.net>
 ;;; Copyright © 2023 Bruno Victal <mirai@makinata.eu>
 ;;; Copyright © 2023 muradm <mail@muradm.net>
+;;; Copyright © 2024 Nigko Yerden <nigko.yerden@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -955,7 +956,11 @@ (define-record-type* <tor-configuration>
   (socks-socket-type tor-configuration-socks-socket-type ; 'tcp or 'unix
                      (default 'tcp))
   (control-socket?  tor-configuration-control-socket-path
-                    (default #f)))
+                    (default #f))
+  (transport-plugin tor-configuration-transport-plugin-path
+                    (default #f))
+  (pluggable-transport tor-configuration-pluggable-transport
+                    (default "obfs4")))
 
 (define %tor-accounts
   ;; User account and groups for Tor.
@@ -988,7 +993,8 @@ (define-configuration/no-serialization tor-onion-service-configuration
 (define (tor-configuration->torrc config)
   "Return a 'torrc' file for CONFIG."
   (match-record config <tor-configuration>
-    (tor config-file hidden-services socks-socket-type control-socket?)
+    (tor config-file hidden-services socks-socket-type control-socket?
+         transport-plugin pluggable-transport)
     (computed-file
      "torrc"
      (with-imported-modules '((guix build utils))
@@ -1027,6 +1033,13 @@ (define (tor-configuration->torrc config)
                                     (cons name mapping)))
                                  hidden-services))
 
+               (when #$transport-plugin
+                 (format port "\
+UseBridges 1
+ClientTransportPlugin ~a exec ~a~%"
+                         #$pluggable-transport
+                         #$transport-plugin))
+
                (display "\
 ### End of automatically generated lines.\n\n" port)
 
@@ -1039,23 +1052,30 @@ (define (tor-configuration->torrc config)
 (define (tor-shepherd-service config)
   "Return a <shepherd-service> running Tor."
   (let* ((torrc (tor-configuration->torrc config))
+         (transport-plugin-path (tor-configuration-transport-plugin-path config))
          (tor   (least-authority-wrapper
                  (file-append (tor-configuration-tor config) "/bin/tor")
                  #:name "tor"
-                 #:mappings (list (file-system-mapping
-                                   (source "/var/lib/tor")
-                                   (target source)
-                                   (writable? #t))
-                                  (file-system-mapping
-                                   (source "/dev/log") ;for syslog
-                                   (target source))
-                                  (file-system-mapping
-                                   (source "/var/run/tor")
-                                   (target source)
-                                   (writable? #t))
-                                  (file-system-mapping
-                                   (source torrc)
-                                   (target source)))
+                 #:mappings (append
+                             (list (file-system-mapping
+                                    (source "/var/lib/tor")
+                                    (target source)
+                                    (writable? #t))
+                                   (file-system-mapping
+                                    (source "/dev/log") ;for syslog
+                                    (target source))
+                                   (file-system-mapping
+                                    (source "/var/run/tor")
+                                    (target source)
+                                    (writable? #t))
+                                   (file-system-mapping
+                                    (source torrc)
+                                    (target source)))
+                             (if transport-plugin-path
+                                 (list (file-system-mapping
+                                        (source transport-plugin-path)
+                                        (target source)))
+                                 '()))
                  #:namespaces (delq 'net %namespaces))))
     (list (shepherd-service
            (provision '(tor))

base-commit: 0f68306268773f0eaa4327e1f6fdcb39442e4a34
-- 
2.41.0