Re: [PATCH 2/2] posix: Improve randomness on try_tempname_len

[Paul Eggert]

On 1/4/21 9:03 AM, Adhemerval Zanella wrote:
> For __GT_NOCREATE (mktemp, tempnam, tmpnam) getrandom is also used
> on first try, otherwise randomness is obtained using the clock plus
> a linear congruential generator.

Why not use getrandom in the first try also for __GT_DIR (mkdtemp) and 
__GT_FILE (mkostemp, mkostemps, mkstemp, mkstemps, tmpfile)? That is 
what Gnulib tempname.c is doing now. This not only simplifies the code, 
it improves resistance to some (admittedly less-likely) attacks.

> Also for getrandom GRND_NONBLOCK is used to avoid blocking indefinitely
> on some older kernels.

Thanks, I installed that part of the proposal into Gnulib by installing 
the attached. The idea is for tempname.c to be identical after we get 
the abovementioned issue worked out.

0001-tempname-don-t-block-for-minutes.patch
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