Bug#911043: On starting (and stopping) rngd

[Thorsten Glaser]

Dixi quod…

>among these I (co‑)manage. With “modprobe virtio-rng”, I
>was able to get it on a VM though. Perhaps relevant info:
>
>$ ls -ld /dev/hw*; grep . /sys/devices/virtual/misc/hw_random/*
>crw------- 1 root root 10, 183 Nov 10 17:04 /dev/hwrng
>/sys/devices/virtual/misc/hw_random/dev:10:183
>grep: /sys/devices/virtual/misc/hw_random/power: Is a directory
>/sys/devices/virtual/misc/hw_random/rng_current:none
>/sys/devices/virtual/misc/hw_random/rng_selected:0
>grep: /sys/devices/virtual/misc/hw_random/subsystem: Is a directory
>/sys/devices/virtual/misc/hw_random/uevent:MAJOR=10
>/sys/devices/virtual/misc/hw_random/uevent:MINOR=183
>/sys/devices/virtual/misc/hw_random/uevent:DEVNAME=hwrng

I erred, the host doesn’t provide entropy here:

$ sudo dd if=/dev/hwrng bs=1 count=1 | hd
dd: error reading '/dev/hwrng': No such device

On another VM, this looks better:

$ grep . /sys/devices/virtual/misc/hw_random/*
/sys/devices/virtual/misc/hw_random/dev:10:183
grep: /sys/devices/virtual/misc/hw_random/power: Is a directory
/sys/devices/virtual/misc/hw_random/rng_available:virtio_rng.0
/sys/devices/virtual/misc/hw_random/rng_current:virtio_rng.0
/sys/devices/virtual/misc/hw_random/rng_selected:0
grep: /sys/devices/virtual/misc/hw_random/subsystem: Is a directory
/sys/devices/virtual/misc/hw_random/uevent:MAJOR=10
/sys/devices/virtual/misc/hw_random/uevent:MINOR=183
/sys/devices/virtual/misc/hw_random/uevent:DEVNAME=hwrng
$ sudo dd if=/dev/hwrng bs=1 count=1 | hd
1+0 records in
1+0 records out
1 byte copied, 0.00145788 s, 0.7 kB/s
00000000  a9                                                |.|
00000001

So we additionally have the case where the character device
exists but is not usable… oh my.

bye,
//mirabilos
-- 
[16:04:33] bkix: "veni vidi violini"
[16:04:45] bkix: "ich kam, sah und vergeigte"...