DRM is also known as "Effective Technological Measures" (ETM). Under Article 11 of the WIPO Copyright Treaty adopted on December 20, 1996, WIPO Copyright requires Member States to provide adequate legal protection against the circumvention of ETM.
Anti-circumvention has since been incorporated into the copyright laws of most jurisdictions around the world. Iin the USA, this is part of the DMCA (1998), in the EU, in European Directive 2001/29/EC (2001), etc.
The presence of ETM clearly challenges the very concept of FLOSS since the presence of ETM may first stop you from sharing an unadapted program with others, and also stop you from creating a functioning adapted version (thereby taking away the four freedoms associated with FLOSS).
The fact that there a laws that prevent circumvention means that even if you have the technical means to circumvent, you may not do so legally.
GPLv2 is dated 1991, before ETM became protected by law, so it does not discuss DRM/ETM.
However, DRM/ETM (along with patents), was on the agenda in the work that resulted in GPLv3 (2007).
Early drafts of GPLv3 first tried to deal with DRM by saying that:
DRM is fundamentally incompatible with the purpose of the GPL, which is to protect users' freedom;
This resulted in protests from many developers, and the original creator of the Linux kernel - Linus Torvalds - wrote:
I literally feel that we do not - as software developers - have the moral right to enforce our rules on hardware manufacturers. We are not crusaders, trying to force people to bow to our superior God. We are trying to show others that co-operation and openness works better.
Eventually, this evolved into the following, which is in part 3 of GPLv3:
When you convey a covered work, you waive any legal power to forbid circumvention of technological measures to the extent such circumvention is effected by exercising rights under this License with respect to the covered work, and you disclaim any intention to limit operation or modification of the work as a means of enforcing, against the work's users, your or third parties' legal rights to forbid circumvention of technological measures.
This compromise text does not forbid DRM/ETM in free software, but provides an explicit permission to circumvent, thereby removing the legal protection otherwise given to ETM by the DCMA and similar laws.
A similar permissions to circumvent has been part of Creative Commons version 4.0 license suite. AFAIK, no other licenses deal explicitly with DRM.
It should be noted that since 1998, ETM has become ubiquitous on several important platforms for distrubuting software. If you distribute your software via Apple iStore and Google play, ETM is added to your distro whether you want to or not. So just banning it (as suggested in the early drafts of GPLv3) will effectivelty cut free software developers off from important distribution channels. We may very well ask people not to use those platforms that incorporate DRM/TPM - but I don't think this strategy will win us friends or influence people.
So how do we, as authors of FLOSS deal with it?
In addition to using a license that allow circumvention of the pesky TPM added by Apple and Google, we should always make it clear that the original source is available and can be downloaded from GitHub or similar sites. Then, those who want to enjoy the four freedoms can get it there, and adapt it (for instance for use on platforms the original author do not support).