[bug#50347] [RFC PATCH] lint: Warn about kernel modules with a suspect license.

[Maxime Devos <maximedevos@telenet.be>]

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X-Debbugs-CC: guix-devel@gnu.org

[CC'ing guix-devel@gnu.org because a wider audience seems in order?]

Hi guix,

This patch adds a 'suspect-license' linter detecting some suspicious
values in the license fields of linux modules:

gnu/packages/file-systems.scm:1317:13: zfs@2.1.0: license appears incompatible with the Linux kernel
gnu/packages/linux.scm:1185:13: acpi-call-linux-module@1.2.1: license appears incompatible with the Linux kernel
gnu/packages/linux.scm:8205:15: ttyebus-linux-module@1.5-0.fe4332a: license appears incompatible with the Linux kernel

For zfs, the issue is the CDDL license.  For the others, the issue
is the gpl3+ license.  See the article by the SFLC for why this linter
detets ZFS:

<https://sfconservancy.org/blog/2016/feb/25/zfs-and-linux/#footnote-other-ZFS-copyright-holders>.

I wrote a little about the CDDL-GPL incompatibility issue
(most likely a GPL violation?) at <https://issues.guix.gnu.org/45692#43>.

Greetings,
Maxime.

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From 851cf20b7d5aed45c3331781afef8de3961f4bb4 Mon Sep 17 00:00:00 2001
From: Maxime Devos <maximedevos@telenet.be>
Date: Thu, 2 Sep 2021 23:30:15 +0200
Subject: [PATCH] lint: Warn about kernel modules with a suspect license.

* guix/lint.scm
  (check-suspect-license): New linter.
  (%local-checkers)[suspect-license]: Register it.
---
 guix/lint.scm | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/guix/lint.scm b/guix/lint.scm
index ffd3f7007e..3a7f3be327 100644
--- a/guix/lint.scm
+++ b/guix/lint.scm
@@ -34,6 +34,7 @@
   #:use-module (guix store)
   #:autoload   (guix base16) (bytevector->base16-string)
   #:use-module (guix base32)
+  #:use-module (guix build-system)
   #:use-module (guix diagnostics)
   #:use-module (guix download)
   #:use-module (guix ftp-client)
@@ -1347,6 +1348,31 @@ of the propagated inputs it pulls in."
       (make-warning package (G_ "invalid license field")
                     #:field 'license)))))
 
+(define (check-suspect-license package)
+  "Warn about suspicious license combinations in PACKAGE."
+  ;; Use 'build-system-name' instead of comparing the build
+  ;; system directly with 'linux-module-build-system' to avoid
+  ;; loading (guix build-system linux-module) when no Linux modules
+  ;; are linted.
+  (define linux-module?
+    (eq? 'linux-module
+         (build-system-name (package-build-system package))))
+  ;; This has plenty of false negatives and should
+  ;; have very few false positives.
+  (define gpl2-only-incompatible?
+    ;; The Linux kernel is GPL-2-only, so GPL3 and later are out.
+    ;; The GPL and CDDL appear to be incompatible, see
+    ;; <https://sfconservancy.org/blog/2016/feb/25/zfs-and-linux/>
+    ;; and <https://www.fsf.org/licensing/zfs-and-linux>.
+    (memq (package-license package)
+          (list gpl3 gpl3+ cddl1.0)))
+  (if (and linux-module? gpl2-only-incompatible?)
+      (list
+       (make-warning package
+                     (G_ "license appears incompatible with the Linux kernel")
+                     #:field 'license))
+      '()))
+
 (define (current-vulnerabilities*)
   "Like 'current-vulnerabilities', but return the empty list upon networking
 or HTTP errors.  This allows network-less operation and makes problems with
@@ -1762,6 +1788,10 @@ them for PACKAGE."
      (description "Make sure the 'license' field is a <license> \
 or a list thereof")
      (check       check-license))
+   (lint-checker
+     (name        'suspect-license)
+     (description "Detect some suspect combinations of licenses")
+     (check       check-suspect-license))
    (lint-checker
      (name        'optional-tests)
      (description "Make sure tests are only run when requested")
-- 
2.33.0


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