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: 0f734e6e76 ("hwrng: add per-device entropy derating")
Reported-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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 142a27f0a7
Fixes: 142a27f0a7 ("hwrng: core - Reset user selected rng by...")
Reported-by: Wirz <spam@lukas-wirz.de>
Tested-by: Wirz <spam@lukas-wirz.de>
Signed-off-by: Michael Büsch <m@bues.ch>
Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Commit 142a27f0a7 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: 142a27f0a7 ("hwrng: core - Reset user selected rng by writing "" to rng_current")
Signed-off-by: Gary R Hook <gary.hook@amd.com>
Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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 <prasannatsmkumar@gmail.com>
reviewed-by: Harald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
pr_err() messages should terminated with a new-line to avoid
other messages being concatenated onto the end.
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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 <freude@linux.vnet.ibm.com>
Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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 <freude@linux.vnet.ibm.com>
Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch move the define for hwrng's miscdev minor number to
include/linux/miscdevice.h.
It's better that all minor number are in the same place.
Rename it to HWRNG_MINOR (from RNG_MISCDEV_MINOR) in he process since
no other miscdev define have MISCDEV in their name.
Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch fix the checkpatch warning about asm/uaccess.h.
In the same time, we sort the headers in alphabetical order.
Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
checkpatch have lot of complaint about header.
Furthermore, the header have some offtopic/useless information.
This patch rewrite a proper header.
Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This was entirely automated, using the script by Al:
PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)
to do the replacement at the end of the merge window.
Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The HWRNG core allocates two buffers during initialization which are
used to obtain random data. After that data is processed, it is now
zeroized as it is possible that the HWRNG core will not be asked to
produce more random data for a long time. This prevents leaving such
sensitive data in memory.
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
hw_random carefully avoids using a stack buffer except in
add_early_randomness(). This causes a crash in virtio_rng if
CONFIG_VMAP_STACK=y.
Reported-by: Matt Mullins <mmullins@mmlx.us>
Tested-by: Matt Mullins <mmullins@mmlx.us>
Fixes: d3cc799647 ("hwrng: fetch randomness only after device init")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
In core rng_buffer and rng_fillbuf is allocated in hwrng_register only
once and it is freed during module exit. This patch moves allocating
rng_buffer and rng_fillbuf from hwrng_register to rng core's init. This
avoids checking whether rng_buffer and rng_fillbuf was allocated from
every hwrng_register call. Also moving them to module init makes it
explicit that it is freed in module exit.
Change in v2:
Fix memory leak when register_miscdev fails.
Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
hwrng kthread can be waiting via hwrng_fillfn for some data from a rng
like virtio-rng:
hwrng D ffff880093e17798 0 382 2 0x00000000
...
Call Trace:
[<ffffffff817339c6>] wait_for_completion_killable+0x96/0x210
[<ffffffffa00aa1b7>] virtio_read+0x57/0xf0 [virtio_rng]
[<ffffffff814f4a35>] hwrng_fillfn+0x75/0x130
[<ffffffff810aa243>] kthread+0xf3/0x110
And when some user program tries to read the /dev node in this state,
we get:
rngd D ffff880093e17798 0 762 1 0x00000004
...
Call Trace:
[<ffffffff817351ac>] mutex_lock_nested+0x15c/0x3e0
[<ffffffff814f478e>] rng_dev_read+0x6e/0x240
[<ffffffff81231958>] __vfs_read+0x28/0xe0
[<ffffffff81232393>] vfs_read+0x83/0x130
And this is indeed unkillable. So use mutex_lock_interruptible
instead of mutex_lock in rng_dev_read and exit immediatelly when
interrupted. And possibly return already read data, if any (as POSIX
allows).
v2: use ERESTARTSYS instead of EINTR
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: <linux-crypto@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
If we attempt to use sysfs to change the current RNG in the usual
way i.e. issuing something like:
`echo 8a8a000.rng > /sys/devices/virtual/misc/hw_random/rng_current`
... it will fail because the code doesn't currently take the '\n'
into consideration. Well, now it does.
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The kthread_run() function can return two different error values
but the hwrng core only checks for -ENOMEM. If the other error
value -EINTR is returned it is assigned to hwrng_fill and later
used on a kthread_stop() call which naturally crashes.
Cc: stable@vger.kernel.org
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Pull char/misc driver updates from Greg KH:
"Here's the big char/misc driver patchset for 4.1-rc1.
Lots of different driver subsystem updates here, nothing major, full
details are in the shortlog.
All of this has been in linux-next for a while"
* tag 'char-misc-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (133 commits)
mei: trace: remove unused TRACE_SYSTEM_STRING
DTS: ARM: OMAP3-N900: Add lis3lv02d support
Documentation: DT: lis302: update wakeup binding
lis3lv02d: DT: add wakeup unit 2 and wakeup threshold
lis3lv02d: DT: use s32 to support negative values
Drivers: hv: hv_balloon: correctly handle num_pages>INT_MAX case
Drivers: hv: hv_balloon: correctly handle val.freeram<num_pages case
mei: replace check for connection instead of transitioning
mei: use mei_cl_is_connected consistently
mei: fix mei_poll operation
hv_vmbus: Add gradually increased delay for retries in vmbus_post_msg()
Drivers: hv: hv_balloon: survive ballooning request with num_pages=0
Drivers: hv: hv_balloon: eliminate jumps in piecewiese linear floor function
Drivers: hv: hv_balloon: do not online pages in offline blocks
hv: remove the per-channel workqueue
hv: don't schedule new works in vmbus_onoffer()/vmbus_onoffer_rescind()
hv: run non-blocking message handlers in the dispatch tasklet
coresight: moving to new "hwtracing" directory
coresight-tmc: Adding a status interface to sysfs
coresight: remove the unnecessary configuration coresight-default-sink
...
Use the new group field of struct miscdevice for managing the sysfs
entries instead of manually adding/removing via device_create_file()
and device_remove_file(). This simplifies the code a lot and fixes
the possible races.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Michael S. Tsirkin
Michael Büsch
Gary R Hook
PrasannaKumar Muralidharan
Arvind Yadav
Harald Freudenberger
Ingo Molnar
Linus Torvalds
David Daney
Corentin LABBE
Stephan Mueller
Andrew Lutomirski
Jiri Slaby
Lee Jones
Martin Schwidefsky
Takashi Iwai