[Bug 1681832] Re: Wrong /dev/hwrng for non-existing generator

[Dan Streetman]

** Changed in: systemd (Ubuntu)
       Status: New => Won't Fix

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Title:
  Wrong /dev/hwrng for non-existing generator

Status in systemd package in Ubuntu:
  Won't Fix

Bug description:
  Hi,

  just ran into a problem:

  I have some software dealing with openssl and some crypto stuff. I
  recently extended it to read bytes from /dev/hwrng if it exists,
  because the software should run on a Raspberry Pi as well. The Raspi
  does not have a clock and usually no user input, thus lack of
  randomness, but a hardware random number generator, so it is necessary
  to use /dev/hwrng if it exists.

  But now the software aborts on regular (intel) PCs, since my regular
  Ubuntu PCs get a /dev/hwrng entry as well, which just throws a „no
  such device“ error when trying to read.

  For some strange reason there is this device entry even if the device
  is not present, causing trouble.

  
  /dev/hwrng should exist only if there is really some hardware generator.

  ProblemType: Bug
  DistroRelease: Ubuntu 16.10
  Package: udev 231-9ubuntu3
  ProcVersionSignature: Ubuntu 4.8.0-45.48-generic 4.8.17
  Uname: Linux 4.8.0-45-generic x86_64
  NonfreeKernelModules: zfs zunicode zcommon znvpair zavl
  ApportVersion: 2.20.3-0ubuntu8.2
  Architecture: amd64
  CurrentDesktop: XFCE
  CustomUdevRuleFiles: 50-usb-hbox.rules 50-net-hbox.rules 70-snap.core.rules
  Date: Tue Apr 11 14:17:28 2017
  InstallationDate: Installed on 2016-04-22 (353 days ago)
  InstallationMedia: Lubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420)
  Lsusb:
   Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
   Bus 001 Device 004: ID 0bda:0821 Realtek Semiconductor Corp. 
   Bus 001 Device 003: ID 046d:c31d Logitech, Inc. Media Keyboard K200
   Bus 001 Device 002: ID 046d:c05b Logitech, Inc. M-U0004 810-001317 [B110 Optical USB Mouse]
   Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
  MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M.
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.8.0-45-generic root=UUID=d0b47754-d5ca-49ec-8190-92a24e58e373 ro rootflags=subvol=@ nosplash noplymouth nomodeset text
  SourcePackage: systemd
  UpgradeStatus: Upgraded to yakkety on 2016-10-17 (176 days ago)
  dmi.bios.date: 03/16/2016
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: P1.50
  dmi.board.name: N3150-NUC
  dmi.board.vendor: ASRock
  dmi.chassis.asset.tag: To Be Filled By O.E.M.
  dmi.chassis.type: 3
  dmi.chassis.vendor: To Be Filled By O.E.M.
  dmi.chassis.version: To Be Filled By O.E.M.
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP1.50:bd03/16/2016:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rnN3150-NUC:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
  dmi.product.name: To Be Filled By O.E.M.
  dmi.product.version: To Be Filled By O.E.M.
  dmi.sys.vendor: To Be Filled By O.E.M.

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