Episode Details

This week we'll be talking with Ryan Lortie and Baptiste Daroussin about GNOME on BSD. Upstream development is finally treating the BSDs as a first class citizen, so we'll hear about how the recent porting efforts have been since.

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Headlines

OpenBSD presents tame

• Theo de Raadt sent out an email detailing OpenBSD's new "tame" subsystem, written by Nicholas Marriott and himself, for restricting what processes can and can't do
• When using tame, programs will switch to a "restricted-service operating mode," limiting them to only the things they actually need to do
• As for the background: "Generally there are two models of operation. The first model requires a major rewrite of application software for effective use (ie. capsicum). The other model in common use lacks granularity, and allows or denies an operation throughout the entire lifetime of a process. As a result, they lack differentiation between program 'initialization' versus 'main servicing loop.' systrace had the same problem. My observation is that programs need a large variety of calls during initialization, but few in their main loops."
• Some initial categories of operation include: computation, memory management, read-write operations on file descriptors, opening of files and, of course, networking
• Restrictions can also be stacked further into the lifespan of the process, but removed abilities can never be regained (obviously)
• Anything that tries to access resources outside of its in-place limits gets terminated with a SIGKILL or, optionally, a SIGABRT (which can produce useful core dumps for investigation)
• Also included are 29 examples of userland programs that get additional protection with very minimal changes to the source - only 2 or 3 lines needing changed in the case of binaries like cat, ps, dmesg, etc.
• This is an initial work-in-progress version of tame, so there may be more improvements or further control options added before it hits a release (very specific access policies can sometimes backfire, however)
• The man page, also included in the mail, provides some specifics about how to integrate tame properly into your code (which, by design, was made very easy to do - making it simple means third party programs are more likely to actually use it)
• Kernel bits are in the tree now, with userland changes starting to trickle in too
• Combined with a myriad of memory protections, tight privilege separation and (above all else) good coding practices, tame