I am trying to run cryptsetup benchmark in a ubuntu 16.04 container. It works fine if I start the container with the --privileged tag. However, if I start an unprivileged container with --cap-add=SYS_MODULE, cryptsetup benchmark errors out as follows:
$ cryptsetup benchmark
##Tests are approximate using memory only (no storage IO).
PBKDF2-sha1 780190 iterations per second
PBKDF2-sha256 504123 iterations per second
PBKDF2-sha512 378820 iterations per second
PBKDF2-ripemd160 524288 iterations per second
PBKDF2-whirlpool 173375 iterations per second
Required kernel crypto interface not available.
Ensure you have algif_skcipher kernel module loaded.
I have loaded the modules dm_crypt, dm_mod and algif_skcipher with modprobe and confirmed it with lsmod, but the error persists. Any ideas as to what could be the problem?
$ docker -v
Docker version 17.03.1-ce, build c6d412e