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%include "default.mgp"
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GPL Workshop
How to (not?) use Free Software
%center
%size 4
by
Harald Welte <hwelte@hmw-consulting.de>
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%page
How to (not) use GPL Software
Contents
About the speaker
Ideas / Goals of the GPL
How to (not) use GPL Software
Complete Source Code
Derivative Works
Collective Works
GPL and Embedded Systems
The biggest GPL Myths
Thanks
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
Introduction
Who is speaking to you?
an independent Free Software developer
who earns his living off Free Software since 1997
who is one of the authors of the Linux kernel firewall system called netfilter/iptables
who has started gpl-violations.org to enforce license compliance
who IS NOT A LAWYER
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
Disclaimer
Legal Disclaimer
All information presented here is provided on an as-is basis
There is no warranty for correctness of legal information
The author is not a lawyer
This does not comprise legal advise
The authors' experience is limited to German copyright law
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
Ideas and Goals of the GNU GPL
Free Software
Software that has fundamental freedoms:
to use it for any purpose
to "help your neighbour" (i.e. make copies)
to study it's functionality (reading source code)
to fix it myself (make modifications and run them)
Copyleft
Is the legal idea to
exercising copyright to grant the above freedoms
assure that nobody can take away the freedom
The GNU General Public License
Is a legal instrument to apply they copyleft idea on software
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
The GNU GPL revisited
Revisiting the GNU General Public License
Regulates distribution of copyrighted code, not usage
Allows distribution of source code and modified source code
The license itself is mentioned
A copy of the license accompanies every copy
Allows distribution of binaries or modified binaries, if
The license itself is mentioned
A copy of the license accompanies every copy
The complete source code is either included with the copy (alternatively a written offer to send the source code on request to any 3rd party)
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%page
How to (not) use GPL Software
Complete Source Code
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"... complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable."
For standard C-language programs, this means:
Source Code
Makefiles
compile-time Configuration (such as kernel .config)
General Rule:
Intent of License is to enable user to run modified versions of the program. They need to be enabled to do so.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
Derivative Works
What is a derivative work?
Not dependent on any particular kind of technology (static/dynamic linking, dlopen, whatever)
Even while the modification can itself be a copyrightable work, the combination with GPL-licensed code is subject to GPL.
As soon as code is written for a specific non-standard API (such as the iptables plugin API), there is significant indication for a derivative work
This position has been successfully enforced out-of-court with two Vendors so far (iptables modules/plugins).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
Derivative Works
Binary-only kernel modules
In-kernel proprietary code (binary kernel modules) are hard to claim GPL compliant
Case-by-case analysis required, as the level of integration into the GPL licensed kernel code depends on particular case
IBM is in the process of getting rid of all binary-only kernel modules. There are exceptions, but they are very clear ones (such as a filesystem port to linux, where the filesystem code already existed under another OS)
There is no general acceptance or tolerance to binary-only kernel modules in the Linux (development) community. Not even Linus himself has ever granted an exception for such modules!
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
Derivative Works
Glue Code
Acts as glue layer between GPL licensed code and proprietary code
Some Vendors think they can avoid the GPL by doing so
Is definitely not a bullet-proof legal solution, especially when it is clearly visible that the only purpose of this glue code is to "get rid" of the GPL.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
Derivative Works
Moral Issues
Apart from what is legally possible, there are moral issues
Even if in a particular case there is no legal way to claim a binary-only kernel module is a derivative work, you might still be acting against the authors' wishes
By shipping binary-only kernel modules, you violate the "moral code of conduct" of the Free Software community
But it is the work of this very community that enables you to build your product based on Free Software
Such action might have long-term detrimental effects on the motivation of FOSS developers (dissatisfaction, demotivation, ...)
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%page
How to (not) use GPL Software
Collective Works
%size 3
"... it is not the intent .. to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works ..."
GPL controls "collective works"
%size 3
"... mere aggregation of another work ... with the program on a volume of a storage or distribution medium does not bring the other work und the scope of this license"
GPL allows "mere aggregation"
like a general-porpose GNU/Linux distribution (SuSE, Red Hat, ...)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
GPL And Embedded Systems
Historical background:
The GPL was written for userspace programs running on existing operating systems
Covering a whole OS (and even userspace programs) is not an ideal match, but if you read it carefully it still makes sense
Toolchain:
%size 3
"... the source code distributed need not include anything that is normally
distributed (in either source or binary form) with the major components
(compiler, kernel, and so on) of the operating system on which the executable
runs, unless that component itself accompanies the executable."
Practical case:
You've modified gcc for a specific embedded platform
Therefore, this gcc is not "normally distributed with the operating system" and you have to distribute it together with the source code
gcc itself is covered under GPL, so you need to provide binaries and source code(!)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
GPL And Embedded Systems
The "Scripts"
(scripts to control compilation and installation, see earlier slide)
In case of embedded hardware, the "scripts" include:
Tools for generating the firmware binary from the source (even if they are technically no 'scripts')
Embedded DRM
Intent of License is to enable user to run modified versions of the program. They need to be enabled to do so.
Result: Signing binaries and only accepting signed versions from the bootloader (without providing the signature key or a possibility to set a new key in the bootloader) is not acceptable!
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
Practical Source Code Offer
Some Rules
The "complete corresponding source code" has to be made available
It has to be made available for each and every object-code version that was distributed
If you strip down the source code offer (e.g. remove proprietary source code), try to see whether the result actually compiles
If the product is mixed free / proprietary software, consider including the proprietary parts (as object code) in the "source code package", so the full firmware image can be rebuilt without having to tear apart an existing image and ripping out those proprietary programs from there.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
The biggest myths about the GPL
The biggest myths about the GPL
The GPL is not enforcible
Software licensed under GPL has no copyright
Unmodified distribution does not require source code availability
The vendor can wait for a source code request (without offering it)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
The most common mistakes
The most common mistakes
not even once reading the GPL text and/or the FAQ from the FSF
not including the GPL license text with the product
not including a written offer with the product
not considering that the GPL also applies to software updates
only providing original source code (e.g. vanilla kernel.org kernel)
not including the "scripts to control installation"
only providing off-site hyperlinks to license and/ore source code
not responding to support requests for source code
charging rediculously high fees for physical shipping of source code
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
License Compatibility
There's lots of Free Software available
Different Software uses different Licenses:
Linux: GPL
glibc: LGPL
apache: Apache Software License
Perl: Artistic
ucd-snmp: BSD
If you combine (i.e. link) differently-licensed software,
check license compatibility
in case of doubt, ask legal person and/or contact software authors
authors might give you an exception or consider making licenses compatible
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
How to (not) use GPL Software
Dual Licensing
The copyright holder (often the original author) can provide alternative licensing
Some projects do this as a business model (reiserfs, MySQL)
In some projects it's impossible due to the extremely distributed copyright (e.g. Linux kernel)
However, in smaller projects it never hurts to ask whether there would be interest in providing an alternative (non-copyleft) licensing
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%page
How to (not) use GPL Software
The End
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Further reading:
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The http://gpl-violations.org/ project
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The Free Software Foundation http://www.fsf.org/, http://www.fsf-europe.org/
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The GNU Project http://www.gnu.org/
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The netfilter homepage http://www.netfilter.org/
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