diff options
| -rw-r--r-- | Documentation/process/license-rules.rst | 62 | ||||
| -rw-r--r-- | include/linux/module.h | 18 |
2 files changed, 79 insertions, 1 deletions
diff --git a/Documentation/process/license-rules.rst b/Documentation/process/license-rules.rst index 2bb8c0fc2238..43b6a1ee0193 100644 --- a/Documentation/process/license-rules.rst +++ b/Documentation/process/license-rules.rst @@ -372,3 +372,65 @@ in the LICENSE subdirectories. This is required to allow tool verification (e.g. checkpatch.pl) and to have the licenses ready to read and extract right from the source, which is recommended by various FOSS organizations, e.g. the `FSFE REUSE initiative <https://reuse.software/>`_. + +_`MODULE_LICENSE` +----------------- + + Loadable kernel modules also require a MODULE_LICENSE() tag. This tag is + neither a replacement for proper source code license information + (SPDX-License-Identifier) nor in any way relevant for expressing or + determining the exact license under which the source code of the module + is provided. + + The sole purpose of this tag is to provide sufficient information + whether the module is free software or proprietary for the kernel + module loader and for user space tools. + + The valid license strings for MODULE_LICENSE() are: + + ============================= ============================================= + "GPL" Module is licensed under GPL version 2. This + does not express any distinction between + GPL-2.0-only or GPL-2.0-or-later. The exact + license information can only be determined + via the license information in the + corresponding source files. + + "GPL v2" Same as "GPL". It exists for historic + reasons. + + "GPL and additional rights" Historical variant of expressing that the + module source is dual licensed under a + GPL v2 variant and MIT license. Please do + not use in new code. + + "Dual MIT/GPL" The correct way of expressing that the + module is dual licensed under a GPL v2 + variant or MIT license choice. + + "Dual BSD/GPL" The module is dual licensed under a GPL v2 + variant or BSD license choice. The exact + variant of the BSD license can only be + determined via the license information + in the corresponding source files. + + "Dual MPL/GPL" The module is dual licensed under a GPL v2 + variant or Mozilla Public License (MPL) + choice. The exact variant of the MPL + license can only be determined via the + license information in the corresponding + source files. + + "Proprietary" The module is under a proprietary license. + This string is solely for proprietary third + party modules and cannot be used for modules + which have their source code in the kernel + tree. Modules tagged that way are tainting + the kernel with the 'P' flag when loaded and + the kernel module loader refuses to link such + modules against symbols which are exported + with EXPORT_SYMBOL_GPL(). + ============================= ============================================= + + + diff --git a/include/linux/module.h b/include/linux/module.h index 9a21fe3509af..3a2402b8d790 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -172,7 +172,7 @@ extern void cleanup_module(void); * The following license idents are currently accepted as indicating free * software modules * - * "GPL" [GNU Public License v2 or later] + * "GPL" [GNU Public License v2] * "GPL v2" [GNU Public License v2] * "GPL and additional rights" [GNU Public License v2 rights and more] * "Dual BSD/GPL" [GNU Public License v2 @@ -186,6 +186,22 @@ extern void cleanup_module(void); * * "Proprietary" [Non free products] * + * Both "GPL v2" and "GPL" (the latter also in dual licensed strings) are + * merely stating that the module is licensed under the GPL v2, but are not + * telling whether "GPL v2 only" or "GPL v2 or later". The reason why there + * are two variants is a historic and failed attempt to convey more + * information in the MODULE_LICENSE string. For module loading the + * "only/or later" distinction is completely irrelevant and does neither + * replace the proper license identifiers in the corresponding source file + * nor amends them in any way. The sole purpose is to make the + * 'Proprietary' flagging work and to refuse to bind symbols which are + * exported with EXPORT_SYMBOL_GPL when a non free module is loaded. + * + * In the same way "BSD" is not a clear license information. It merely + * states, that the module is licensed under one of the compatible BSD + * license variants. The detailed and correct license information is again + * to be found in the corresponding source files. + * * There are dual licensed components, but when running with Linux it is the * GPL that is relevant so this is a non issue. Similarly LGPL linked with GPL * is a GPL combined work. |