Public bug reported: SRU Justification
[Impact] GKE made an inquiry about the source of entropy for /dev/hwrng. Their public documentation (https://cloud.google.com/compute/docs/instances/enabling-virtio-rng) specifies that virtio_rng is the default, but they observed that the TPM's RNG is used instead on current GKE images. Besides aligning with their public docs, using virtio_rng means that the host is responsible for providing the most secure hardware entropy source, which is a better default than assuming that the most secure source on that particular machine is the TPM (or RDRAND instructions, etc). [Fix] Configure CONFIG_HW_RANDOM_VIRTIO=y for all targeted kernels. [Test Plan] Executing $ cat /sys/devices/virtual/misc/hw_random/rng_current Should return "virtio_rng.0" [Regression potential] There should be a very low chance of regression. Hardware RNG entropy sources in theory are identical in behavior, and the test plan above can determine what the active source of entropy is. ** Affects: linux-gke (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-gke in Ubuntu. https://bugs.launchpad.net/bugs/2106782 Title: virtio_rng should be the source of hardware entropy Status in linux-gke package in Ubuntu: New Bug description: SRU Justification [Impact] GKE made an inquiry about the source of entropy for /dev/hwrng. Their public documentation (https://cloud.google.com/compute/docs/instances/enabling-virtio-rng) specifies that virtio_rng is the default, but they observed that the TPM's RNG is used instead on current GKE images. Besides aligning with their public docs, using virtio_rng means that the host is responsible for providing the most secure hardware entropy source, which is a better default than assuming that the most secure source on that particular machine is the TPM (or RDRAND instructions, etc). [Fix] Configure CONFIG_HW_RANDOM_VIRTIO=y for all targeted kernels. [Test Plan] Executing $ cat /sys/devices/virtual/misc/hw_random/rng_current Should return "virtio_rng.0" [Regression potential] There should be a very low chance of regression. Hardware RNG entropy sources in theory are identical in behavior, and the test plan above can determine what the active source of entropy is. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-gke/+bug/2106782/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
