Can I take BSD licensed code and distribute it under GPL?

Question

Or in more general terms: Can I take code which is licensed under a permissive open source license (like the BSD license) and distribute it under a copyleft free software license (like the GPL)?

Microsoft and Apple seem to be allowed to take BSD (or similar) licensed code and distribute it under a proprietary license.

In addition, the permissive nature of the BSD license has allowed many other operating systems, both free and proprietary, to incorporate BSD code. For example, Microsoft Windows has used BSD-derived code in its implementation of TCP/IP and bundles recompiled versions of BSD's command-line networking tools since Windows 2000. Also Darwin, the system on which Apple's Mac OS X is built, is a derivative of 4.4BSD-Lite2 and FreeBSD. Various commercial Unix operating systems, such as Solaris, also contain varying amounts of BSD code.

^Wikipedia

But then there is this story from 2007 where some BSD people got mighty mad at linux kernel developers who took BSD licensed code and "relicensed" it under GPL.

KernelTrap has an interesting article in which Theo de Raadt discusses the legal implications of the recent relicensing of OpenBSD's BSD licensed Atheros driver under the GPL. De Raadt says, "it has been like pulling teeth since (most) Linux wireless guys and the SFLC do not wish to admit fault. I think that the Linux wireless guys should really think hard about this problem, how they look, and the legal risks they place upon the future of their source code bodies." He stressed that the theory that BSD code can simply be relicensed to the GPL without making significant changes to the code is false, adding, "'in their zeal to get the code under their own license, some of these Linux wireless developers have broken copyright law repeatedly. But to even get to the point where they broke copyright law, they had to bypass a whole series of ethical considerations too."

^{OpenBSD Journal}

I have to admit that I do not fully understand the legal implication of some of the terms. For example: incorporate, derive/derivative, or bundle.

Note that I used the term "distribute" in my question. A term which is not used in both the wikipedia article and the OpenBSD Journal.

Note also that I am not asking whether I can relicense the code. I am asking whether I can redistribute the code under a different license. I understand that I cannot relicense code if it is not my copyright.

What I mean with "distribute" is roughly as follows:

1. Download BSD licensed code.
2. Put GPL license file in root of project and GPL header in every relevant file and add note in README that the code is also licensed under GPL. Note that the BSD license is not removed.
3. Upload the code to some website for everyone to download.
4. ???
5. PROFIT!!1

As far as I understand a downloader now has the option to take the code under the terms of the BSD license or under the terms of the GPL license.

If that is not allowed then please explain what Microsoft and Apple are doing.

Answer 1

If the BSD license in question is the two- or three-clause variant (i.e. without the advertising clause), I think you're technically allowed to do it, but you couldn't really enforce it: anyone who obtained a copy of the code you're distributing could re-use the BSD-licensed code under the provisions of the BSD license only, and the GPL wouldn't apply. (The GPL would apply to anything you hold the copyright for, and to the agregate; i.e. resulting binaries would be GPL. But for that to be meaningful you'd have to add code of your own...)

What Microsoft and Apple are doing is complying with the BSD license.

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

If they don't redistribute source code then that doesn't apply. (Nothing forces them to redistribute source code; that's why the BSD license is called a permissive license.)

Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

You'll find that Microsoft and Apple products which incorporate BSD code do satisfy this, either in the documentation, or typically in the "About" box.

The name of the author may not be used to endorse or promote products derived from this software without specific prior written permission.

Somehow I doubt Microsoft or Apple would be interested in doing this anyway.

The final clause is the lack of warranty, which everyone disclaims anyway, so there's no change there either.

The four-clause BSD license is GPL-incompatible so in that case you wouldn't be able to distribute under the GPL.

Answer 2

First of all: There are three different BSD-licenses. The original BSD-license has four clauses, including a advertisement-clause. This advertisement-clause is incompatible with the GPL, so you cannot redistribute it as GPL, the same as you cannot combine it with GPL-code.

The modified BSD-licenses drop this clause and make BSD compatible with GPL. This technically means you can redistribute it as GPL, as long as you follow the terms of the original license. That includes to put the text of the BSD-license with your product.

Answer 3

Theo de Raadt is wrong. Plain and simple.

The BSD is a permissive license which allows to incorporate the licensed work under a different license, no matter if permissive, copyleft or proprietary. That's the point of using a permissive license.

When the original authors of OpenBSD didn't want this to happen, they shouldn't have used the BSD license in the first place. When one does not want their work getting taken away from them like this, they are free to publish their work under a copyleft or proprietary license.

Answer 4

You can legally relicense under conditions compatible with the original license (meaning most forms of the BSD license will allow relicensing under the GPL). It just carries very little meaning for an unchanged source since only one of the actual copyright holders has standing to enforce the license. So tell Theo de Raadt that you relicensed under the GPL some program copyrighted by him (in accordance to what the BSD licensing allowed you) and the recipient went ahead and ignored your relicensing, and can he please sue this recipient over breaking the relicensing you did in accordance with what Theo's license allowed you to do?

Good luck with that. Most people license under BSD-like licenses exactly because they don't want to bother with suing people. So you better have some copyrights of your own in the software in question or your relicensing will mostly be meaningless even if there are no other copies available from other sources anymore: it would require entirely unusual circumstances to interest the copyright holders in enforcing your license.

Answer 5

The key here is relicensing. You absolutely can incorporate BSD code to a GPL project as long as you comply with the license (giving credit where credit is due), but under no circumstance can you arbitrarily relicense it without the permission of the original copyright holder like Philipp here is saying. Not only would that be illegal, it most definitely would make you a bit of a knob.

The GPL

From GNU FAQ: What does it mean to be GPL Compatible:

It means that the other license and the GNU GPL are compatible; you can combine code released under the other license with code released under the GNU GPL in one larger program.

BSD-style Licenses

Generally speaking many (perhaps even most) BSD-style licenses are GPL-compatible, thus they may be combined in this way.

• They may not be licensed the other way around!
• The original 4-clause BSD license is not GPL-compatible due to a restriction about advertising, but I don't think many people actually use the original license. See more in the Wikipedia BSD License entry.
• Combining code does not affect their respective license statuses; all this means that BSD-code can be added to GPL code.

Relicensing Without Permission

You should refer to your local copyright law. IANAL, but I would imagine that in most jurisdictions only the copyright-holder (and those authorized by said holder) can decide the conditions their work is distributed under. One does not own code made by someone else even if they obtained the code legally free. While licensing code under BSD gives relatively free hands for public to do what they please with the code itself, it does not relinquish copyright to the code--quite the opposite in fact.

Answer 6

No, you cannot.

A licence is a way for a copyright holder to grant certain rights to others that are otherwise reserved. You don't own any copyrights to any stuff you just download from the internet, unless someone specifically transfers their copyright to you (e.g., what IEEE requires for scientific papers in order to publish them -- the authors must assign their copyright to IEEE).

If you make sufficient changes to the code, then you might be able to choose a different licence for your changes. But should you? The issue with the BSD/Linux controversy in regards to Atheros comes down to the ethical considerations -- the GPL advocates claim that BSD licence allows companies to not release the source code (even though a lot of companies do, since it's cheaper that way, and a lot of diffs get incorporated into all BSDs that originate from these companies like Netflix, Apple and even Oracle), yet instead of playing nice with the BSD guys themselves, Linux guys do the exact opposite than what all of those commercial companies are actually doing -- they (re)licence their changes to GPL, making sure that all such changes are forever barred from going back to the BSD projects. (Specifically, the conflict was fuelled by the fact that such re-licensing has occurred when only trivial and non-copyrightable changes have been performed on the existing code.)

Answer 7

From the BSD license:

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

You absolutely cannot distribute source code or binary w/o retaining the original BSD license with the code or making people aware that the associated binary code is under a BSD license.