Support for /dev/*random in OpenSSL 1.1.1

Michael Brunnbauer brunni at
Wed Sep 11 15:48:01 UTC 2019

hi all,

I have glibc 2.30 with Kernel 4.9.191 but unfortunately I compiled glibc with
old Kernel headers from Linux 3.16.46. It seems that as a result of this, my 
getrandom() and getentropy() are stubs that always fail with ENOSYS. This 
leads to:

./util/ apps/openssl rand -hex 10
4145686272:error:2406C06E:random number generator:RAND_DRBG_instantiate:error retrieving entropy:crypto/rand/drbg_lib.c:342:

Fine I thought, supply --with-rand-seed=devrandom to Configure and be done
with it until you can fix your glibc. Nope - same result.

Now I see this in e_os.h:

 * Linux kernels 4.8 and later changes how their random device works and there
 * is no reliable way to tell that /dev/urandom has been seeded -- getentropy(2)
 * should be used instead.
#    define DEVRANDOM_SAFE_KERNEL        4, 8
#   endif

So openSSL 1.1.1 will not support /dev/*random with Kernels > 4.8 ?

I can fix the kernel headers before compiling the next release of glibc but
this is some months away.

Is there anything I can do now? I don't like the idea to recompile glibc - 
Version upgrades are much easier to deploy than replacing the current version.


Michael Brunnbauer

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