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%include "default.mgp"
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GPL Workshop
How to (not?) use Free Software


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by

Harald Welte <hwelte@hmw-consulting.de>



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How to (not) use GPL Software
Contents

	About the speaker
	Ideas / Goals of the GPL
	The GNU GPL Revisited
	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
The GNU GPL Revisited
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
The GNU GPL Revisited
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)

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
The GNU GPL Revisited
Complete Source Code

%size 3
"... 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
The GNU GPL Revisited
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
The GNU GPL Revisited
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
The GNU GPL Revisited
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
The GNU GPL Revisited
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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The GNU GPL Revisited
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"

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"... 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
The GNU GPL Revisited
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
The GNU GPL Revisited
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!
		

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%page
The GNU GPL Revisited
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
The GNU GPL Revisited
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
The GNU GPL Revisited
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
The GNU GPL Revisited
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
The GNU GPL Revisited
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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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/
%%	http://management.itmanagersjournal.com/management/04/05/31/1733229.shtml?tid=85&tid=4


personal git repositories of Harald Welte. Your mileage may vary