Messages in this thread | | | From | Hannes Frederic Sowa <> | Subject | Re: [PATCH, RFC] random: introduce getrandom(2) system call | Date | Wed, 23 Jul 2014 14:10:16 +0200 |
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On Wed, Jul 23, 2014, at 13:52, George Spelvin wrote: > I keep wishing for a more general solution. For example, some way to > have a "spare" extra fd that could be accessed with a special O_NOFAIL > flag. > > That would allow any number of library functions to not fail, such as > logging from nasty corner cases. > > But you'd have to provide one per thread, and block non-fatal signals > while it was open, so you don't get reentrancy problems. Ick. > > > This overly-specialized system call (and worse yet, a blocking > system call that you can't put into a poll() loop) just feels ugly > to me. Is it *absolutely* necessary?
One point that often came up besides fd exhaustion is missing /dev/u?random device nodes in chroot environments.
I also thought about a more general interface, like e.g. an opennod(dev_t device, int flags) call but all those ideas ended up being very complex changes besides having design issues. getrandom is simple and solves a real problem.
The only problem I see, that we allow access to /dev/random without checking any permission bits like we did on opening /dev/random before and we cannot restrict applications to deplete the whole entropy pool.
> For example, how about simply making getentropy() a library function that > aborts if it can't open /dev/urandom? If you're suffering fd exhaustion, > you're being DoSed already.
Maybe applications want to mitigate fd exhaustion.
Bye, Hannes
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