kernel.git/drivers/char/hw_random/core.c, branch linux-5.3.y

hwrng: core - don't wait on add_early_randomness()

2019-10-05T13:12:36Z

commit 78887832e76541f77169a24ac238fccb51059b63 upstream. add_early_randomness() is called by hwrng_register() when the hardware is added. If this hardware and its module are present at boot, and if there is no data available the boot hangs until data are available and can't be interrupted. For instance, in the case of virtio-rng, in some cases the host can be not able to provide enough entropy for all the guests. We can have two easy ways to reproduce the problem but they rely on misconfiguration of the hypervisor or the egd daemon: - if virtio-rng device is configured to connect to the egd daemon of the host but when the virtio-rng driver asks for data the daemon is not connected, - if virtio-rng device is configured to connect to the egd daemon of the host but the egd daemon doesn't provide data. The guest kernel will hang at boot until the virtio-rng driver provides enough data. To avoid that, call rng_get_data() in non-blocking mode (wait=0) from add_early_randomness(). Signed-off-by: Laurent Vivier Fixes: d9e797261933 ("hwrng: add randomness to system from rng...") Cc: Reviewed-by: Theodore Ts'o Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

docs: admin-guide: add a series of orphaned documents

2019-07-15T14:03:02Z

There are lots of documents that belong to the admin-guide but are on random places (most under Documentation root dir). Move them to the admin guide. Signed-off-by: Mauro Carvalho Chehab Acked-by: Alexandre Belloni Acked-by: Bartlomiej Zolnierkiewicz

hwrng: core - document the quality field

2018-10-05T02:16:56Z

quality field is currently documented as being 'per mill'. In fact the math involved is: add_hwgenerator_randomness((void *)rng_fillbuf, rc, rc * current_quality * 8 >> 10); thus the actual definition is "bits of entropy per 1024 bits of input". The current documentation seems to have confused multiple people in the past, let's fix the documentation to match code. An alternative is to change core to match driver expectations, replacing rc * current_quality * 8 >> 10 with rc * current_quality / 1000 but that has performance costs, so probably isn't a good option. Fixes: 0f734e6e768 ("hwrng: add per-device entropy derating") Reported-by: "Dr. David Alan Gilbert" Signed-off-by: Michael S. Tsirkin Signed-off-by: Herbert Xu

hwrng: core - Always drop the RNG in hwrng_unregister()

2018-06-15T15:06:49Z

enable_best_rng() is used in hwrng_unregister() to switch away from the currently active RNG, if that is the one currently being removed. However enable_best_rng() might fail, if the next RNG's init routine fails. In that case enable_best_rng() will return an error code and the currently active RNG will remain active. After unregistering this might lead to crashes due to use-after-free. Fix this by dropping the currently active RNG, if enable_best_rng() failed. This will result in no RNG to be active, if the next-best one failed to initialize. This problem was introduced by 142a27f0a731ddcf467546960a5585970ca98e21 Fixes: 142a27f0a731 ("hwrng: core - Reset user selected rng by...") Reported-by: Wirz Tested-by: Wirz Signed-off-by: Michael Büsch Cc: stable@vger.kernel.org Signed-off-by: Herbert Xu

hwrng: core - Clean up RNG list when last hwrng is unregistered

2017-12-22T09:03:36Z

Commit 142a27f0a731 added support for a "best" RNG, and in doing so introduced a hang from rmmod/modprobe -r when the last RNG on the list was unloaded. When the hwrng list is depleted, return the global variables to their original state and decrement all references to the object. Fixes: 142a27f0a731 ("hwrng: core - Reset user selected rng by writing "" to rng_current") Signed-off-by: Gary R Hook Reviewed-by: PrasannaKumar Muralidharan Signed-off-by: Herbert Xu

hwrng: core - Reset user selected rng by writing "" to rng_current

2017-11-03T14:11:25Z

User is able to select a chosen rng by writing its name to rng_current but there is no way to reset it without unbinding the rng. Let user write "" to rng_current and delesect the chosen rng. Signed-off-by: PrasannaKumar Muralidharan reviewed-by: Harald Freudenberger Signed-off-by: Herbert Xu

hwrng: core - pr_err() strings should end with newlines

2017-10-12T14:54:49Z

pr_err() messages should terminated with a new-line to avoid other messages being concatenated onto the end. Signed-off-by: Arvind Yadav Signed-off-by: Herbert Xu

hwrng: remember rng chosen by user

2017-07-18T10:16:09Z

When a user chooses a rng source via sysfs attribute this rng should be sticky, even when other sources with better quality to register. This patch introduces a simple way to remember the user's choice. This is reflected by a new sysfs attribute file 'rng_selected' which shows if the current rng has been chosen by userspace. The new attribute file shows '1' for user selected rng and '0' otherwise. Signed-off-by: Harald Freudenberger Reviewed-by: PrasannaKumar Muralidharan Signed-off-by: Herbert Xu

hwrng: use rng source with best quality

2017-07-18T10:16:08Z

This patch rewoks the hwrng to always use the rng source with best entropy quality. On registation and unregistration the hwrng now tries to choose the best (= highest quality value) rng source. The handling of the internal list of registered rng sources is now always sorted by quality and the top most rng chosen. Signed-off-by: Harald Freudenberger Reviewed-by: PrasannaKumar Muralidharan Signed-off-by: Herbert Xu

sched/headers: Prepare to move signal wakeup & sigpending methods from into

2017-03-02T07:42:32Z

Fix up affected files that include this signal functionality via sched.h. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar