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Random number generator updates for Linux 6.0-rc1. 

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Merge tag 'random-6.0-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull random number generator updates from Jason Donenfeld:
 "Though there's been a decent amount of RNG-related development during
  this last cycle, not all of it is coming through this tree, as this
  cycle saw a shift toward tackling early boot time seeding issues,
  which took place in other trees as well.

  Here's a summary of the various patches:

   - The CONFIG_ARCH_RANDOM .config option and the "nordrand" boot
     option have been removed, as they overlapped with the more widely
     supported and more sensible options, CONFIG_RANDOM_TRUST_CPU and
     "random.trust_cpu". This change allowed simplifying a bit of arch
     code.

   - x86's RDRAND boot time test has been made a bit more robust, with
     RDRAND disabled if it's clearly producing bogus results. This would
     be a tip.git commit, technically, but I took it through random.git
     to avoid a large merge conflict.

   - The RNG has long since mixed in a timestamp very early in boot, on
     the premise that a computer that does the same things, but does so
     starting at different points in wall time, could be made to still
     produce a different RNG state. Unfortunately, the clock isn't set
     early in boot on all systems, so now we mix in that timestamp when
     the time is actually set.

   - User Mode Linux now uses the host OS's getrandom() syscall to
     generate a bootloader RNG seed and later on treats getrandom() as
     the platform's RDRAND-like faculty.

   - The arch_get_random_{seed_,}_long() family of functions is now
     arch_get_random_{seed_,}_longs(), which enables certain platforms,
     such as s390, to exploit considerable performance advantages from
     requesting multiple CPU random numbers at once, while at the same
     time compiling down to the same code as before on platforms like
     x86.

   - A small cleanup changing a cmpxchg() into a try_cmpxchg(), from
     Uros.

   - A comment spelling fix"

More info about other random number changes that come in through various
architecture trees in the full commentary in the pull request:

  https://lore.kernel.org/all/20220731232428.2219258-1-Jason@zx2c4.com/

* tag 'random-6.0-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
  random: correct spelling of "overwrites"
  random: handle archrandom with multiple longs
  um: seed rng using host OS rng
  random: use try_cmpxchg in _credit_init_bits
  timekeeping: contribute wall clock to rng on time change
  x86/rdrand: Remove "nordrand" flag in favor of "random.trust_cpu"
  random: remove CONFIG_ARCH_RANDOM
This commit is contained in:
Linus Torvalds 2022-08-02 17:31:35 -07:00
parent 569bede0cf 7f637be4d4
commit a0b09f2d6f
34 changed files with 204 additions and 300 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
Documentation/admin-guide/kernel-parameters.txt
View File

@ -3741,11 +3741,6 @@
noreplace-smp [X86-32,SMP] Don't replace SMP instructions
with UP alternatives
nordrand [X86] Disable kernel use of the RDRAND and
RDSEED instructions even if they are supported
by the processor. RDRAND and RDSEED are still
available to user space applications.
noresume [SWSUSP] Disables resume and restores original swap
space.

2
arch/arm/include/asm/archrandom.h
View File

@ -7,4 +7,6 @@ static inline bool __init smccc_probe_trng(void)
return false;
}
#include <asm-generic/archrandom.h>
#endif /* _ASM_ARCHRANDOM_H */

8
arch/arm64/Kconfig
View File

@ -1895,14 +1895,6 @@ config ARM64_E0PD
This option enables E0PD for TTBR1 where available.
config ARCH_RANDOM
bool "Enable support for random number generation"
default y
help
Random number generation (part of the ARMv8.5 Extensions)
provides a high bandwidth, cryptographically secure
hardware random number generator.
config ARM64_AS_HAS_MTE
# Initial support for MTE went in binutils 2.32.0, checked with
# ".arch armv8.5-a+memtag" below. However, this was incomplete

112
arch/arm64/include/asm/archrandom.h
View File

@ -2,8 +2,6 @@
#ifndef _ASM_ARCHRANDOM_H
#define _ASM_ARCHRANDOM_H
#ifdef CONFIG_ARCH_RANDOM
#include <linux/arm-smccc.h>
#include <linux/bug.h>
#include <linux/kernel.h>
@ -60,7 +58,7 @@ static inline bool __arm64_rndrrs(unsigned long *v)
return ok;
}
static inline bool __must_check arch_get_random_long(unsigned long *v)
static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
{
/*
* Only support the generic interface after we have detected
@ -68,27 +66,15 @@ static inline bool __must_check arch_get_random_long(unsigned long *v)
* cpufeature code and with potential scheduling between CPUs
* with and without the feature.
*/
if (cpus_have_const_cap(ARM64_HAS_RNG) && __arm64_rndr(v))
return true;
return false;
if (max_longs && cpus_have_const_cap(ARM64_HAS_RNG) && __arm64_rndr(v))
return 1;
return 0;
}
static inline bool __must_check arch_get_random_int(unsigned int *v)
static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs)
{
if (cpus_have_const_cap(ARM64_HAS_RNG)) {
unsigned long val;
if (__arm64_rndr(&val)) {
*v = val;
return true;
}
}
return false;
}
static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
{
struct arm_smccc_res res;
if (!max_longs)
return 0;
/*
* We prefer the SMCCC call, since its semantics (return actual
@ -97,10 +83,23 @@ static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
* (the output of a pseudo RNG freshly seeded by a TRNG).
*/
if (smccc_trng_available) {
arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, 64, &res);
struct arm_smccc_res res;
max_longs = min_t(size_t, 3, max_longs);
arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, max_longs * 64, &res);
if ((int)res.a0 >= 0) {
*v = res.a3;
return true;
switch (max_longs) {
case 3:
*v++ = res.a1;
fallthrough;
case 2:
*v++ = res.a2;
fallthrough;
case 1:
*v++ = res.a3;
break;
}
return max_longs;
}
}
@ -110,32 +109,9 @@ static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
* enough to implement this API if no other entropy source exists.
*/
if (cpus_have_const_cap(ARM64_HAS_RNG) && __arm64_rndrrs(v))
return true;
return 1;
return false;
}
static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
{
struct arm_smccc_res res;
unsigned long val;
if (smccc_trng_available) {
arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, 32, &res);
if ((int)res.a0 >= 0) {
*v = res.a3 & GENMASK(31, 0);
return true;
}
}
if (cpus_have_const_cap(ARM64_HAS_RNG)) {
if (__arm64_rndrrs(&val)) {
*v = val;
return true;
}
}
return false;
return 0;
}
static inline bool __init __early_cpu_has_rndr(void)
@ -145,34 +121,40 @@ static inline bool __init __early_cpu_has_rndr(void)
return (ftr >> ID_AA64ISAR0_EL1_RNDR_SHIFT) & 0xf;
}
static inline bool __init __must_check
arch_get_random_seed_long_early(unsigned long *v)
static inline size_t __init __must_check
arch_get_random_seed_longs_early(unsigned long *v, size_t max_longs)
{
WARN_ON(system_state != SYSTEM_BOOTING);
if (!max_longs)
return 0;
if (smccc_trng_available) {
struct arm_smccc_res res;
arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, 64, &res);
max_longs = min_t(size_t, 3, max_longs);
arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, max_longs * 64, &res);
if ((int)res.a0 >= 0) {
*v = res.a3;
return true;
switch (max_longs) {
case 3:
*v++ = res.a1;
fallthrough;
case 2:
*v++ = res.a2;
fallthrough;
case 1:
*v++ = res.a3;
break;
}
return max_longs;
}
}
if (__early_cpu_has_rndr() && __arm64_rndr(v))
return true;
return 1;
return false;
return 0;
}
#define arch_get_random_seed_long_early arch_get_random_seed_long_early
#define arch_get_random_seed_longs_early arch_get_random_seed_longs_early
#else /* !CONFIG_ARCH_RANDOM */
static inline bool __init smccc_probe_trng(void)
{
return false;
}
#endif /* CONFIG_ARCH_RANDOM */
#endif /* _ASM_ARCHRANDOM_H */

2
arch/arm64/kernel/cpufeature.c
View File

@ -2502,7 +2502,6 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.cpu_enable = cpu_enable_e0pd,
},
#endif
#ifdef CONFIG_ARCH_RANDOM
{
.desc = "Random Number Generator",
.capability = ARM64_HAS_RNG,
@ -2514,7 +2513,6 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.sign = FTR_UNSIGNED,
.min_field_value = 1,
},
#endif
#ifdef CONFIG_ARM64_BTI
{
.desc = "Branch Target Identification",

3
arch/powerpc/Kconfig
View File

@ -1257,9 +1257,6 @@ config PHYSICAL_START
default "0x00000000"
endif
config ARCH_RANDOM
def_bool n
config PPC_LIB_RHEAP
bool

33
arch/powerpc/include/asm/archrandom.h
View File

@ -2,41 +2,20 @@
#ifndef _ASM_POWERPC_ARCHRANDOM_H
#define _ASM_POWERPC_ARCHRANDOM_H
#ifdef CONFIG_ARCH_RANDOM
#include <asm/machdep.h>
static inline bool __must_check arch_get_random_long(unsigned long *v)
static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
{
return false;
return 0;
}
static inline bool __must_check arch_get_random_int(unsigned int *v)
static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs)
{
return false;
if (max_longs && ppc_md.get_random_seed && ppc_md.get_random_seed(v))
return 1;
return 0;
}
static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
{
if (ppc_md.get_random_seed)
return ppc_md.get_random_seed(v);
return false;
}
static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
{
unsigned long val;
bool rc;
rc = arch_get_random_seed_long(&val);
if (rc)
*v = val;
return rc;
}
#endif /* CONFIG_ARCH_RANDOM */
#ifdef CONFIG_PPC_POWERNV
int powernv_hwrng_present(void);
int powernv_get_random_long(unsigned long *v);

2
arch/powerpc/include/asm/machdep.h
View File

@ -200,9 +200,7 @@ struct machdep_calls {
ssize_t (*cpu_release)(const char *, size_t);
#endif
#ifdef CONFIG_ARCH_RANDOM
int (*get_random_seed)(unsigned long *v);
#endif
};
extern void e500_idle(void);

2
arch/powerpc/kvm/book3s_hv.c
View File

@ -1207,7 +1207,7 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
break;
#endif
case H_RANDOM:
if (!arch_get_random_seed_long(&vcpu->arch.regs.gpr[4]))
if (!arch_get_random_seed_longs(&vcpu->arch.regs.gpr[4], 1))
ret = H_HARDWARE;
break;
case H_RPT_INVALIDATE:

1
arch/powerpc/platforms/microwatt/Kconfig
View File

@ -6,7 +6,6 @@ config PPC_MICROWATT
select PPC_ICS_NATIVE
select PPC_ICP_NATIVE
select PPC_UDBG_16550
select ARCH_RANDOM
help
This option enables support for FPGA-based Microwatt implementations.

1
arch/powerpc/platforms/powernv/Kconfig
View File

@ -12,7 +12,6 @@ config PPC_POWERNV
select EPAPR_BOOT
select PPC_INDIRECT_PIO
select PPC_UDBG_16550
select ARCH_RANDOM
select CPU_FREQ
select PPC_DOORBELL
select MMU_NOTIFIER

1
arch/powerpc/platforms/pseries/Kconfig
View File

@ -19,7 +19,6 @@ config PPC_PSERIES
select PPC_UDBG_16550
select PPC_DOORBELL
select HOTPLUG_CPU
select ARCH_RANDOM
select FORCE_SMP
select SWIOTLB
default y

15
arch/s390/Kconfig
View File

@ -508,21 +508,6 @@ config KEXEC_SIG
verification for the corresponding kernel image type being
loaded in order for this to work.
config ARCH_RANDOM
def_bool y
prompt "s390 architectural random number generation API"
help
Enable the s390 architectural random number generation API
to provide random data for all consumers within the Linux
kernel.
When enabled the arch_random_* functions declared in linux/random.h
are implemented. The implementation is based on the s390 CPACF
instruction subfunction TRNG which provides a real true random
number generator.
If unsure, say Y.
config KERNEL_NOBP
def_bool n
prompt "Enable modified branch prediction for the kernel by default"

1
arch/s390/configs/zfcpdump_defconfig
View File

@ -15,7 +15,6 @@ CONFIG_TUNE_ZEC12=y
# CONFIG_COMPAT is not set
CONFIG_NR_CPUS=2
CONFIG_HZ_100=y
# CONFIG_ARCH_RANDOM is not set
# CONFIG_RELOCATABLE is not set
# CONFIG_CHSC_SCH is not set
# CONFIG_SCM_BUS is not set

2
arch/s390/crypto/Makefile
View File

@ -15,7 +15,7 @@ obj-$(CONFIG_CRYPTO_CHACHA_S390) += chacha_s390.o
obj-$(CONFIG_S390_PRNG) += prng.o
obj-$(CONFIG_CRYPTO_GHASH_S390) += ghash_s390.o
obj-$(CONFIG_CRYPTO_CRC32_S390) += crc32-vx_s390.o
obj-$(CONFIG_ARCH_RANDOM) += arch_random.o
obj-y += arch_random.o
crc32-vx_s390-y := crc32-vx.o crc32le-vx.o crc32be-vx.o
chacha_s390-y := chacha-glue.o chacha-s390.o

33
arch/s390/include/asm/archrandom.h
View File

@ -11,8 +11,6 @@
#ifndef _ASM_S390_ARCHRANDOM_H
#define _ASM_S390_ARCHRANDOM_H
#ifdef CONFIG_ARCH_RANDOM
#include <linux/static_key.h>
#include <linux/preempt.h>
#include <linux/atomic.h>
@ -21,37 +19,20 @@
DECLARE_STATIC_KEY_FALSE(s390_arch_random_available);
extern atomic64_t s390_arch_random_counter;
static inline bool __must_check arch_get_random_long(unsigned long *v)
static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
{
return false;
return 0;
}
static inline bool __must_check arch_get_random_int(unsigned int *v)
{
return false;
}
static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs)
{
if (static_branch_likely(&s390_arch_random_available) &&
in_task()) {
cpacf_trng(NULL, 0, (u8 *)v, sizeof(*v));
atomic64_add(sizeof(*v), &s390_arch_random_counter);
return true;
cpacf_trng(NULL, 0, (u8 *)v, max_longs * sizeof(*v));
atomic64_add(max_longs * sizeof(*v), &s390_arch_random_counter);
return max_longs;
}
return false;
return 0;
}
static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
{
if (static_branch_likely(&s390_arch_random_available) &&
in_task()) {
cpacf_trng(NULL, 0, (u8 *)v, sizeof(*v));
atomic64_add(sizeof(*v), &s390_arch_random_counter);
return true;
}
return false;
}
#endif /* CONFIG_ARCH_RANDOM */
#endif /* _ASM_S390_ARCHRANDOM_H */

2
arch/s390/kernel/setup.c
View File

@ -876,10 +876,8 @@ static void __init setup_randomness(void)
add_device_randomness(&vmms->vm, sizeof(vmms->vm[0]) * vmms->count);
memblock_free(vmms, PAGE_SIZE);
#ifdef CONFIG_ARCH_RANDOM
if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
static_branch_enable(&s390_arch_random_available);
#endif
}
/*

25
arch/um/include/asm/archrandom.h Normal file
View File

@ -0,0 +1,25 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_UM_ARCHRANDOM_H__
#define __ASM_UM_ARCHRANDOM_H__
#include <linux/types.h>
/* This is from <os.h>, but better not to #include that in a global header here. */
ssize_t os_getrandom(void *buf, size_t len, unsigned int flags);
static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
{
ssize_t ret;
ret = os_getrandom(v, max_longs * sizeof(*v), 0);
if (ret < 0)
return 0;
return ret / sizeof(*v);
}
static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs)
{
return 0;
}
#endif

7
arch/um/include/shared/os.h
View File

@ -11,6 +11,12 @@
#include <irq_user.h>
#include <longjmp.h>
#include <mm_id.h>
/* This is to get size_t */
#ifndef __UM_HOST__
#include <linux/types.h>
#else
#include <sys/types.h>
#endif
#define CATCH_EINTR(expr) while ((errno = 0, ((expr) < 0)) && (errno == EINTR))
@ -243,6 +249,7 @@ extern void stack_protections(unsigned long address);
extern int raw(int fd);
extern void setup_machinename(char *machine_out);
extern void setup_hostinfo(char *buf, int len);
extern ssize_t os_getrandom(void *buf, size_t len, unsigned int flags);
extern void os_dump_core(void) __attribute__ ((noreturn));
extern void um_early_printk(const char *s, unsigned int n);
extern void os_fix_helper_signals(void);

8
arch/um/kernel/um_arch.c
View File

@ -16,6 +16,7 @@
#include <linux/sched/task.h>
#include <linux/kmsg_dump.h>
#include <linux/suspend.h>
#include <linux/random.h>
#include <asm/processor.h>
#include <asm/cpufeature.h>
@ -406,6 +407,8 @@ int __init __weak read_initrd(void)
void __init setup_arch(char **cmdline_p)
{
u8 rng_seed[32];
stack_protections((unsigned long) &init_thread_info);
setup_physmem(uml_physmem, uml_reserved, physmem_size, highmem);
mem_total_pages(physmem_size, iomem_size, highmem);
@ -416,6 +419,11 @@ void __init setup_arch(char **cmdline_p)
strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
*cmdline_p = command_line;
setup_hostinfo(host_info, sizeof host_info);
if (os_getrandom(rng_seed, sizeof(rng_seed), 0) == sizeof(rng_seed)) {
add_bootloader_randomness(rng_seed, sizeof(rng_seed));
memzero_explicit(rng_seed, sizeof(rng_seed));
}
}
void __init check_bugs(void)

6
arch/um/os-Linux/util.c
View File

@ -14,6 +14,7 @@
#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/utsname.h>
#include <sys/random.h>
#include <init.h>
#include <os.h>
@ -96,6 +97,11 @@ static inline void __attribute__ ((noreturn)) uml_abort(void)
exit(127);
}
ssize_t os_getrandom(void *buf, size_t len, unsigned int flags)
{
return getrandom(buf, len, flags);
}
/*
* UML helper threads must not handle SIGWINCH/INT/TERM
*/

9
arch/x86/Kconfig
View File

@ -1812,15 +1812,6 @@ config ARCH_USES_PG_UNCACHED
def_bool y
depends on X86_PAT
config ARCH_RANDOM
def_bool y
prompt "x86 architectural random number generator" if EXPERT
help
Enable the x86 architectural RDRAND instruction
(Intel Bull Mountain technology) to generate random numbers.
If supported, this is a high bandwidth, cryptographically
secure hardware random number generator.
config X86_UMIP
def_bool y
prompt "User Mode Instruction Prevention" if EXPERT

55
arch/x86/include/asm/archrandom.h
View File

@ -31,20 +31,6 @@ static inline bool __must_check rdrand_long(unsigned long *v)
return false;
}
static inline bool __must_check rdrand_int(unsigned int *v)
{
bool ok;
unsigned int retry = RDRAND_RETRY_LOOPS;
do {
asm volatile("rdrand %[out]"
CC_SET(c)
: CC_OUT(c) (ok), [out] "=r" (*v));
if (ok)
return true;
} while (--retry);
return false;
}
static inline bool __must_check rdseed_long(unsigned long *v)
{
bool ok;
@ -54,48 +40,23 @@ static inline bool __must_check rdseed_long(unsigned long *v)
return ok;
}
static inline bool __must_check rdseed_int(unsigned int *v)
{
bool ok;
asm volatile("rdseed %[out]"
CC_SET(c)
: CC_OUT(c) (ok), [out] "=r" (*v));
return ok;
}
/*
* These are the generic interfaces; they must not be declared if the
* stubs in <linux/random.h> are to be invoked,
* i.e. CONFIG_ARCH_RANDOM is not defined.
* stubs in <linux/random.h> are to be invoked.
*/
#ifdef CONFIG_ARCH_RANDOM
static inline bool __must_check arch_get_random_long(unsigned long *v)
static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
{
return static_cpu_has(X86_FEATURE_RDRAND) ? rdrand_long(v) : false;
return max_longs && static_cpu_has(X86_FEATURE_RDRAND) && rdrand_long(v) ? 1 : 0;
}
static inline bool __must_check arch_get_random_int(unsigned int *v)
static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs)
{
return static_cpu_has(X86_FEATURE_RDRAND) ? rdrand_int(v) : false;
return max_longs && static_cpu_has(X86_FEATURE_RDSEED) && rdseed_long(v) ? 1 : 0;
}
static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
{
return static_cpu_has(X86_FEATURE_RDSEED) ? rdseed_long(v) : false;
}
static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
{
return static_cpu_has(X86_FEATURE_RDSEED) ? rdseed_int(v) : false;
}
extern void x86_init_rdrand(struct cpuinfo_x86 *c);
#else /* !CONFIG_ARCH_RANDOM */
static inline void x86_init_rdrand(struct cpuinfo_x86 *c) { }
#endif /* !CONFIG_ARCH_RANDOM */
#ifndef CONFIG_UML
void x86_init_rdrand(struct cpuinfo_x86 *c);
#endif
#endif /* ASM_X86_ARCHRANDOM_H */

2
arch/x86/kernel/cpu/amd.c
View File

@ -808,7 +808,7 @@ static void clear_rdrand_cpuid_bit(struct cpuinfo_x86 *c)
return;
/*
* The nordrand option can clear X86_FEATURE_RDRAND, so check for
* The self-test can clear X86_FEATURE_RDRAND, so check for
* RDRAND support using the CPUID function directly.
*/
if (!(cpuid_ecx(1) & BIT(30)) || rdrand_force)

63
arch/x86/kernel/cpu/rdrand.c
View File

@ -11,56 +11,39 @@
#include <asm/archrandom.h>
#include <asm/sections.h>
static int __init x86_rdrand_setup(char *s)
{
setup_clear_cpu_cap(X86_FEATURE_RDRAND);
setup_clear_cpu_cap(X86_FEATURE_RDSEED);
return 1;
}
__setup("nordrand", x86_rdrand_setup);
/*
* RDRAND has Built-In-Self-Test (BIST) that runs on every invocation.
* Run the instruction a few times as a sanity check.
* If it fails, it is simple to disable RDRAND here.
* Run the instruction a few times as a sanity check. Also make sure
* it's not outputting the same value over and over, which has happened
* as a result of past CPU bugs.
*
* If it fails, it is simple to disable RDRAND and RDSEED here.
*/
#define SANITY_CHECK_LOOPS 8
#ifdef CONFIG_ARCH_RANDOM
void x86_init_rdrand(struct cpuinfo_x86 *c)
{
unsigned int changed = 0;
unsigned long tmp, prev;
int i;
enum { SAMPLES = 8, MIN_CHANGE = 5 };
unsigned long sample, prev;
bool failure = false;
size_t i, changed;
if (!cpu_has(c, X86_FEATURE_RDRAND))
return;
for (i = 0; i < SANITY_CHECK_LOOPS; i++) {
if (!rdrand_long(&tmp)) {
for (changed = 0, i = 0; i < SAMPLES; ++i) {
if (!rdrand_long(&sample)) {
failure = true;
break;
}
changed += i && sample != prev;
prev = sample;
}
if (changed < MIN_CHANGE)
failure = true;
if (failure) {
clear_cpu_cap(c, X86_FEATURE_RDRAND);
pr_warn_once("rdrand: disabled\n");
return;
clear_cpu_cap(c, X86_FEATURE_RDSEED);
pr_emerg("RDRAND is not reliable on this platform; disabling.\n");
}
}
/*
* Stupid sanity-check whether RDRAND does *actually* generate
* some at least random-looking data.
*/
prev = tmp;
for (i = 0; i < SANITY_CHECK_LOOPS; i++) {
if (rdrand_long(&tmp)) {
if (prev != tmp)
changed++;
prev = tmp;
}
}
if (WARN_ON_ONCE(!changed))
pr_emerg(
"RDRAND gives funky smelling output, might consider not using it by booting with \"nordrand\"");
}
#endif

2
arch/x86/kernel/espfix_64.c
View File

@ -100,7 +100,7 @@ static void init_espfix_random(void)
* This is run before the entropy pools are initialized,
* but this is hopefully better than nothing.
*/
if (!arch_get_random_long(&rand)) {
if (!arch_get_random_longs(&rand, 1)) {
/* The constant is an arbitrary large prime */
rand = rdtsc();
rand *= 0xc345c6b72fd16123UL;

1
drivers/char/Kconfig
View File

@ -431,7 +431,6 @@ config ADI
config RANDOM_TRUST_CPU
bool "Initialize RNG using CPU RNG instructions"
default y
depends on ARCH_RANDOM
help
Initialize the RNG using random numbers supplied by the CPU's
RNG instructions (e.g. RDRAND), if supported and available. These

9
drivers/char/hw_random/s390-trng.c
View File

@ -108,7 +108,6 @@ static ssize_t trng_counter_show(struct device *dev,
{
u64 dev_counter = atomic64_read(&trng_dev_counter);
u64 hwrng_counter = atomic64_read(&trng_hwrng_counter);
#if IS_ENABLED(CONFIG_ARCH_RANDOM)
u64 arch_counter = atomic64_read(&s390_arch_random_counter);
return sysfs_emit(buf,
@ -118,14 +117,6 @@ static ssize_t trng_counter_show(struct device *dev,
"total: %llu\n",
dev_counter, hwrng_counter, arch_counter,
dev_counter + hwrng_counter + arch_counter);
#else
return sysfs_emit(buf,
"trng: %llu\n"
"hwrng: %llu\n"
"total: %llu\n",
dev_counter, hwrng_counter,
dev_counter + hwrng_counter);
#endif
}
static DEVICE_ATTR(byte_counter, 0444, trng_counter_show, NULL);

51
drivers/char/random.c
View File

@ -229,7 +229,7 @@ static void crng_reseed(void)
/*
* This generates a ChaCha block using the provided key, and then
* immediately overwites that key with half the block. It returns
* immediately overwrites that key with half the block. It returns
* the resultant ChaCha state to the user, along with the second
* half of the block containing 32 bytes of random data that may
* be used; random_data_len may not be greater than 32.
@ -596,12 +596,20 @@ static void extract_entropy(void *buf, size_t len)
unsigned long rdseed[32 / sizeof(long)];
size_t counter;
} block;
size_t i;
size_t i, longs;
for (i = 0; i < ARRAY_SIZE(block.rdseed); ++i) {
if (!arch_get_random_seed_long(&block.rdseed[i]) &&
!arch_get_random_long(&block.rdseed[i]))
block.rdseed[i] = random_get_entropy();
for (i = 0; i < ARRAY_SIZE(block.rdseed);) {
longs = arch_get_random_seed_longs(&block.rdseed[i], ARRAY_SIZE(block.rdseed) - i);
if (longs) {
i += longs;
continue;
}
longs = arch_get_random_longs(&block.rdseed[i], ARRAY_SIZE(block.rdseed) - i);
if (longs) {
i += longs;
continue;
}
block.rdseed[i++] = random_get_entropy();
}
spin_lock_irqsave(&input_pool.lock, flags);
@ -643,10 +651,10 @@ static void __cold _credit_init_bits(size_t bits)
add = min_t(size_t, bits, POOL_BITS);
do {
orig = READ_ONCE(input_pool.init_bits);
do {
new = min_t(unsigned int, POOL_BITS, orig + add);
} while (cmpxchg(&input_pool.init_bits, orig, new) != orig);
} while (!try_cmpxchg(&input_pool.init_bits, &orig, new));
if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) {
crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */
@ -776,22 +784,31 @@ static struct notifier_block pm_notifier = { .notifier_call = random_pm_notifica
int __init random_init(const char *command_line)
{
ktime_t now = ktime_get_real();
unsigned int i, arch_bits;
unsigned long entropy;
size_t i, longs, arch_bits;
unsigned long entropy[BLAKE2S_BLOCK_SIZE / sizeof(long)];
#if defined(LATENT_ENTROPY_PLUGIN)
static const u8 compiletime_seed[BLAKE2S_BLOCK_SIZE] __initconst __latent_entropy;
_mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed));
#endif
for (i = 0, arch_bits = BLAKE2S_BLOCK_SIZE * 8;
i < BLAKE2S_BLOCK_SIZE; i += sizeof(entropy)) {
if (!arch_get_random_seed_long_early(&entropy) &&
!arch_get_random_long_early(&entropy)) {
entropy = random_get_entropy();
arch_bits -= sizeof(entropy) * 8;
for (i = 0, arch_bits = sizeof(entropy) * 8; i < ARRAY_SIZE(entropy);) {
longs = arch_get_random_seed_longs(entropy, ARRAY_SIZE(entropy) - i);
if (longs) {
_mix_pool_bytes(entropy, sizeof(*entropy) * longs);
i += longs;
continue;
}
_mix_pool_bytes(&entropy, sizeof(entropy));
longs = arch_get_random_longs(entropy, ARRAY_SIZE(entropy) - i);
if (longs) {
_mix_pool_bytes(entropy, sizeof(*entropy) * longs);
i += longs;
continue;
}
entropy[0] = random_get_entropy();
_mix_pool_bytes(entropy, sizeof(*entropy));
arch_bits -= sizeof(*entropy) * 8;
++i;
}
_mix_pool_bytes(&now, sizeof(now));
_mix_pool_bytes(utsname(), sizeof(*(utsname())));

1
include/asm-generic/Kbuild
View File

@ -5,6 +5,7 @@
# asm headers from the host architecutre.)
mandatory-y += atomic.h
mandatory-y += archrandom.h
mandatory-y += barrier.h
mandatory-y += bitops.h
mandatory-y += bug.h

15
include/asm-generic/archrandom.h Normal file
View File

@ -0,0 +1,15 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_GENERIC_ARCHRANDOM_H__
#define __ASM_GENERIC_ARCHRANDOM_H__
static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
{
return 0;
}
static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs)
{
return 0;
}
#endif

21
include/linux/random.h
View File

@ -106,32 +106,25 @@ declare_get_random_var_wait(long, unsigned long)
*/
#include <linux/prandom.h>
#ifdef CONFIG_ARCH_RANDOM
# include <asm/archrandom.h>
#else
static inline bool __must_check arch_get_random_long(unsigned long *v) { return false; }
static inline bool __must_check arch_get_random_int(unsigned int *v) { return false; }
static inline bool __must_check arch_get_random_seed_long(unsigned long *v) { return false; }
static inline bool __must_check arch_get_random_seed_int(unsigned int *v) { return false; }
#endif
#include <asm/archrandom.h>
/*
* Called from the boot CPU during startup; not valid to call once
* secondary CPUs are up and preemption is possible.
*/
#ifndef arch_get_random_seed_long_early
static inline bool __init arch_get_random_seed_long_early(unsigned long *v)
#ifndef arch_get_random_seed_longs_early
static inline size_t __init arch_get_random_seed_longs_early(unsigned long *v, size_t max_longs)
{
WARN_ON(system_state != SYSTEM_BOOTING);
return arch_get_random_seed_long(v);
return arch_get_random_seed_longs(v, max_longs);
}
#endif
#ifndef arch_get_random_long_early
static inline bool __init arch_get_random_long_early(unsigned long *v)
#ifndef arch_get_random_longs_early
static inline bool __init arch_get_random_longs_early(unsigned long *v, size_t max_longs)
{
WARN_ON(system_state != SYSTEM_BOOTING);
return arch_get_random_long(v);
return arch_get_random_longs(v, max_longs);
}
#endif

7
kernel/time/timekeeping.c
View File

@ -23,6 +23,7 @@
#include <linux/pvclock_gtod.h>
#include <linux/compiler.h>
#include <linux/audit.h>
#include <linux/random.h>
#include "tick-internal.h"
#include "ntp_internal.h"
@ -1343,8 +1344,10 @@ out:
/* Signal hrtimers about time change */
clock_was_set(CLOCK_SET_WALL);
if (!ret)
if (!ret) {
audit_tk_injoffset(ts_delta);
add_device_randomness(ts, sizeof(*ts));
}
return ret;
}
@ -2430,6 +2433,7 @@ int do_adjtimex(struct __kernel_timex *txc)
ret = timekeeping_validate_timex(txc);
if (ret)
return ret;
add_device_randomness(txc, sizeof(*txc));
if (txc->modes & ADJ_SETOFFSET) {
struct timespec64 delta;
@ -2447,6 +2451,7 @@ int do_adjtimex(struct __kernel_timex *txc)
audit_ntp_init(&ad);
ktime_get_real_ts64(&ts);
add_device_randomness(&ts, sizeof(ts));
raw_spin_lock_irqsave(&timekeeper_lock, flags);
write_seqcount_begin(&tk_core.seq);

1
tools/testing/selftests/wireguard/qemu/kernel.config
View File

@ -58,7 +58,6 @@ CONFIG_NO_HZ_IDLE=y
CONFIG_NO_HZ_FULL=n
CONFIG_HZ_PERIODIC=n
CONFIG_HIGH_RES_TIMERS=y
CONFIG_ARCH_RANDOM=y
CONFIG_FILE_LOCKING=y
CONFIG_POSIX_TIMERS=y
CONFIG_DEVTMPFS=y