The <asm/archrandom.h> header is a random.c private detail, not
something to be called by other code. As such, don't make it
automatically available by way of random.h.
Cc: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Most hw_random devices return entropy which is assumed to be of full
quality, but driver authors don't bother setting the quality knob. Some
hw_random devices return less than full quality entropy, and then driver
authors set the quality knob. Therefore, the entropy crediting should be
opt-out rather than opt-in per-driver, to reflect the actual reality on
the ground.
For example, the two Raspberry Pi RNG drivers produce full entropy
randomness, and both EDK2 and U-Boot's drivers for these treat them as
such. The result is that EFI then uses these numbers and passes the to
Linux, and Linux credits them as boot, thereby initializing the RNG.
Yet, in Linux, the quality knob was never set to anything, and so on the
chance that Linux is booted without EFI, nothing is ever credited.
That's annoying.
The same pattern appears to repeat itself throughout various drivers. In
fact, very very few drivers have bothered setting quality=1024.
Looking at the git history of existing drivers and corresponding mailing
list discussion, this conclusion tracks. There's been a decent amount of
discussion about drivers that set quality < 1024 -- somebody read and
interepreted a datasheet, or made some back of the envelope calculation
somehow. But there's been very little, if any, discussion about most
drivers where the quality is just set to 1024 or unset (or set to 1000
when the authors misunderstood the API and assumed it was base-10 rather
than base-2); in both cases the intent was fairly clear of, "this is a
hardware random device; it's fine."
So let's invert this logic. A hw_random struct's quality knob now
controls the maximum quality a driver can produce, or 0 to specify 1024.
Then, the module-wide switch called "default_quality" is changed to
represent the maximum quality of any driver. By default it's 1024, and
the quality of any particular driver is then given by:
min(default_quality, rng->quality ?: 1024);
This way, the user can still turn this off for weird reasons (and we can
replace whatever driver-specific disabling hacks existed in the past),
yet we get proper crediting for relevant RNGs.
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
- Rework copy_oldmem_page() callback to take an iov_iter.
This includes few prerequisite updates and fixes to the
oldmem reading code.
- Rework cpufeature implementation to allow for various CPU feature
indications, which is not only limited to hardware capabilities,
but also allows CPU facilities.
- Use the cpufeature rework to autoload Ultravisor module when CPU
facility 158 is available.
- Add ELF note type for encrypted CPU state of a protected virtual CPU.
The zgetdump tool from s390-tools package will decrypt the CPU state
using a Customer Communication Key and overwrite respective notes to
make the data accessible for crash and other debugging tools.
- Use vzalloc() instead of vmalloc() + memset() in ChaCha20 crypto test.
- Fix incorrect recovery of kretprobe modified return address in stacktrace.
- Switch the NMI handler to use generic irqentry_nmi_enter() and
irqentry_nmi_exit() helper functions.
- Rework the cryptographic Adjunct Processors (AP) pass-through design
to support dynamic changes to the AP matrix of a running guest as well
as to implement more of the AP architecture.
- Minor boot code cleanups.
- Grammar and typo fixes to hmcdrv and tape drivers.
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Merge tag 's390-5.20-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Alexander Gordeev:
- Rework copy_oldmem_page() callback to take an iov_iter.
This includes a few prerequisite updates and fixes to the oldmem
reading code.
- Rework cpufeature implementation to allow for various CPU feature
indications, which is not only limited to hardware capabilities, but
also allows CPU facilities.
- Use the cpufeature rework to autoload Ultravisor module when CPU
facility 158 is available.
- Add ELF note type for encrypted CPU state of a protected virtual CPU.
The zgetdump tool from s390-tools package will decrypt the CPU state
using a Customer Communication Key and overwrite respective notes to
make the data accessible for crash and other debugging tools.
- Use vzalloc() instead of vmalloc() + memset() in ChaCha20 crypto
test.
- Fix incorrect recovery of kretprobe modified return address in
stacktrace.
- Switch the NMI handler to use generic irqentry_nmi_enter() and
irqentry_nmi_exit() helper functions.
- Rework the cryptographic Adjunct Processors (AP) pass-through design
to support dynamic changes to the AP matrix of a running guest as
well as to implement more of the AP architecture.
- Minor boot code cleanups.
- Grammar and typo fixes to hmcdrv and tape drivers.
* tag 's390-5.20-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (46 commits)
Revert "s390/smp: enforce lowcore protection on CPU restart"
Revert "s390/smp: rework absolute lowcore access"
Revert "s390/smp,ptdump: add absolute lowcore markers"
s390/unwind: fix fgraph return address recovery
s390/nmi: use irqentry_nmi_enter()/irqentry_nmi_exit()
s390: add ELF note type for encrypted CPU state of a PV VCPU
s390/smp,ptdump: add absolute lowcore markers
s390/smp: rework absolute lowcore access
s390/setup: rearrange absolute lowcore initialization
s390/boot: cleanup adjust_to_uv_max() function
s390/smp: enforce lowcore protection on CPU restart
s390/tape: fix comment typo
s390/hmcdrv: fix Kconfig "its" grammar
s390/docs: fix warnings for vfio_ap driver doc
s390/docs: fix warnings for vfio_ap driver lock usage doc
s390/crash: support multi-segment iterators
s390/crash: use static swap buffer for copy_to_user_real()
s390/crash: move copy_to_user_real() to crash_dump.c
s390/zcore: fix race when reading from hardware system area
s390/crash: fix incorrect number of bytes to copy to user space
...
Rework cpufeature implementation to allow for various cpu feature
indications, which is not only limited to hwcap bits. This is achieved
by adding a sequential list of cpu feature numbers, where each of them
is mapped to an entry which indicates what this number is about.
Each entry contains a type member, which indicates what feature
name space to look into (e.g. hwcap, or cpu facility). If wanted this
allows also to automatically load modules only in e.g. z/VM
configurations.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Link: https://lore.kernel.org/r/20220713125644.16121-2-seiden@linux.ibm.com
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
When RDRAND was introduced, there was much discussion on whether it
should be trusted and how the kernel should handle that. Initially, two
mechanisms cropped up, CONFIG_ARCH_RANDOM, a compile time switch, and
"nordrand", a boot-time switch.
Later the thinking evolved. With a properly designed RNG, using RDRAND
values alone won't harm anything, even if the outputs are malicious.
Rather, the issue is whether those values are being *trusted* to be good
or not. And so a new set of options were introduced as the real
ones that people use -- CONFIG_RANDOM_TRUST_CPU and "random.trust_cpu".
With these options, RDRAND is used, but it's not always credited. So in
the worst case, it does nothing, and in the best case, maybe it helps.
Along the way, CONFIG_ARCH_RANDOM's meaning got sort of pulled into the
center and became something certain platforms force-select.
The old options don't really help with much, and it's a bit odd to have
special handling for these instructions when the kernel can deal fine
with the existence or untrusted existence or broken existence or
non-existence of that CPU capability.
Simplify the situation by removing CONFIG_ARCH_RANDOM and using the
ordinary asm-generic fallback pattern instead, keeping the two options
that are actually used. For now it leaves "nordrand" for now, as the
removal of that will take a different route.
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
coccicheck complains about the use of snprintf() in sysfs show functions.
Fix the following coccicheck warning:
drivers/char/hw_random/s390-trng.c:114:8-16: WARNING: use scnprintf or sprintf.
drivers/char/hw_random/s390-trng.c:122:8-16: WARNING: use scnprintf or sprintf.
Use sysfs_emit instead of scnprintf or sprintf makes more sense.
Signed-off-by: Qing Wang <wangqing@vivo.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The s390-trng does provide 100% entropy. The quality value is supported
to be between 1 and 1024 and not 1..1000. Use 1024 to make this driver
the preferred one. If we ever have a better driver that has the same
quality but is faster we can change this again when merging the new
driver. No need to be conservative.
This makes sure that the hw variant is preferred over things like
virtio-rng, where the hypervisor has a potential to be misconfigured
and thus should have a slightly lower confidence.
Cc: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 only
as published by the free software foundation
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531081036.798138318@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch introduces a new device driver s390-trng for the
s390 platform which exploits the new PRNO TRNG cpacf
subfunction. The true-random-number-generator is accessible
from userspace, by default visible as /dev/trng. The driver
also registers at the kernel build-in hwrng API to feed the
hwrng with fresh entropy data. This generic device driver
for hardware random data is visible from userspace as
/dev/hwrng.
Signed-off-by: Harald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
