Messages in this thread | | | From | Linus Torvalds <> | Date | Mon, 16 Sep 2019 10:07:27 -0700 | Subject | Re: Linux 5.3-rc8 |
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On Mon, Sep 16, 2019 at 10:00 AM Theodore Y. Ts'o <tytso@mit.edu> wrote: > > How /dev/random blocks is very different from how getrandom(2) blocks. > Getrandom(2) blocks until the CRNG, and then it never blocks again.
Yes and no.
getrandom() very much blocks exactly like /dev/random, when you give it the GRND_RANDOM flag.
Which is completely broken, and was already known to be broken. So that flag is just plain stupid.
And getrandom() does *not* block like /dev/urandom does (ie not at all), which was actually useful, and very widely used.
So you really have the worst of both worlds.
Yes, getrandom(0) does what /dev/random _should_ have done, and what getrandom(GRND_RANDOM) should be but isn't.
But by making the choice it did, we now have three useless flag combinations, and we lack one people _want_ and need.
And this design mistake very much caused the particular bug we are now hitting.
Linus
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