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authorLinus Torvalds <torvalds@linux-foundation.org>2022-12-13 01:22:22 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2022-12-13 01:22:22 +0100
commit268325bda5299836a6ad4c3952474a2be125da5f (patch)
tree5f7b22109b7a21d0aab68cab8de0ee201426aae1 /arch/arm64/include/asm
parentMerge branch 'for-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/denni... (diff)
parentrandom: include <linux/once.h> in the right header (diff)
downloadlinux-268325bda5299836a6ad4c3952474a2be125da5f.tar.xz
linux-268325bda5299836a6ad4c3952474a2be125da5f.zip
Merge tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random
Pull random number generator updates from Jason Donenfeld: - Replace prandom_u32_max() and various open-coded variants of it, there is now a new family of functions that uses fast rejection sampling to choose properly uniformly random numbers within an interval: get_random_u32_below(ceil) - [0, ceil) get_random_u32_above(floor) - (floor, U32_MAX] get_random_u32_inclusive(floor, ceil) - [floor, ceil] Coccinelle was used to convert all current users of prandom_u32_max(), as well as many open-coded patterns, resulting in improvements throughout the tree. I'll have a "late" 6.1-rc1 pull for you that removes the now unused prandom_u32_max() function, just in case any other trees add a new use case of it that needs to converted. According to linux-next, there may be two trivial cases of prandom_u32_max() reintroductions that are fixable with a 's/.../.../'. So I'll have for you a final conversion patch doing that alongside the removal patch during the second week. This is a treewide change that touches many files throughout. - More consistent use of get_random_canary(). - Updates to comments, documentation, tests, headers, and simplification in configuration. - The arch_get_random*_early() abstraction was only used by arm64 and wasn't entirely useful, so this has been replaced by code that works in all relevant contexts. - The kernel will use and manage random seeds in non-volatile EFI variables, refreshing a variable with a fresh seed when the RNG is initialized. The RNG GUID namespace is then hidden from efivarfs to prevent accidental leakage. These changes are split into random.c infrastructure code used in the EFI subsystem, in this pull request, and related support inside of EFISTUB, in Ard's EFI tree. These are co-dependent for full functionality, but the order of merging doesn't matter. - Part of the infrastructure added for the EFI support is also used for an improvement to the way vsprintf initializes its siphash key, replacing an sleep loop wart. - The hardware RNG framework now always calls its correct random.c input function, add_hwgenerator_randomness(), rather than sometimes going through helpers better suited for other cases. - The add_latent_entropy() function has long been called from the fork handler, but is a no-op when the latent entropy gcc plugin isn't used, which is fine for the purposes of latent entropy. But it was missing out on the cycle counter that was also being mixed in beside the latent entropy variable. So now, if the latent entropy gcc plugin isn't enabled, add_latent_entropy() will expand to a call to add_device_randomness(NULL, 0), which adds a cycle counter, without the absent latent entropy variable. - The RNG is now reseeded from a delayed worker, rather than on demand when used. Always running from a worker allows it to make use of the CPU RNG on platforms like S390x, whose instructions are too slow to do so from interrupts. It also has the effect of adding in new inputs more frequently with more regularity, amounting to a long term transcript of random values. Plus, it helps a bit with the upcoming vDSO implementation (which isn't yet ready for 6.2). - The jitter entropy algorithm now tries to execute on many different CPUs, round-robining, in hopes of hitting even more memory latencies and other unpredictable effects. It also will mix in a cycle counter when the entropy timer fires, in addition to being mixed in from the main loop, to account more explicitly for fluctuations in that timer firing. And the state it touches is now kept within the same cache line, so that it's assured that the different execution contexts will cause latencies. * tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (23 commits) random: include <linux/once.h> in the right header random: align entropy_timer_state to cache line random: mix in cycle counter when jitter timer fires random: spread out jitter callback to different CPUs random: remove extraneous period and add a missing one in comments efi: random: refresh non-volatile random seed when RNG is initialized vsprintf: initialize siphash key using notifier random: add back async readiness notifier random: reseed in delayed work rather than on-demand random: always mix cycle counter in add_latent_entropy() hw_random: use add_hwgenerator_randomness() for early entropy random: modernize documentation comment on get_random_bytes() random: adjust comment to account for removed function random: remove early archrandom abstraction random: use random.trust_{bootloader,cpu} command line option only stackprotector: actually use get_random_canary() stackprotector: move get_random_canary() into stackprotector.h treewide: use get_random_u32_inclusive() when possible treewide: use get_random_u32_{above,below}() instead of manual loop treewide: use get_random_u32_below() instead of deprecated function ...
Diffstat (limited to 'arch/arm64/include/asm')
-rw-r--r--arch/arm64/include/asm/archrandom.h48
-rw-r--r--arch/arm64/include/asm/stackprotector.h9
2 files changed, 11 insertions, 46 deletions
diff --git a/arch/arm64/include/asm/archrandom.h b/arch/arm64/include/asm/archrandom.h
index 109e2a4454be..2f5f3da34782 100644
--- a/arch/arm64/include/asm/archrandom.h
+++ b/arch/arm64/include/asm/archrandom.h
@@ -5,6 +5,7 @@
#include <linux/arm-smccc.h>
#include <linux/bug.h>
#include <linux/kernel.h>
+#include <linux/irqflags.h>
#include <asm/cpufeature.h>
#define ARM_SMCCC_TRNG_MIN_VERSION 0x10000UL
@@ -58,6 +59,13 @@ static inline bool __arm64_rndrrs(unsigned long *v)
return ok;
}
+static __always_inline bool __cpu_has_rng(void)
+{
+ if (unlikely(!system_capabilities_finalized() && !preemptible()))
+ return this_cpu_has_cap(ARM64_HAS_RNG);
+ return cpus_have_const_cap(ARM64_HAS_RNG);
+}
+
static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
{
/*
@@ -66,7 +74,7 @@ static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t
* cpufeature code and with potential scheduling between CPUs
* with and without the feature.
*/
- if (max_longs && cpus_have_const_cap(ARM64_HAS_RNG) && __arm64_rndr(v))
+ if (max_longs && __cpu_has_rng() && __arm64_rndr(v))
return 1;
return 0;
}
@@ -108,7 +116,7 @@ static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, s
* reseeded after each invocation. This is not a 100% fit but good
* enough to implement this API if no other entropy source exists.
*/
- if (cpus_have_const_cap(ARM64_HAS_RNG) && __arm64_rndrrs(v))
+ if (__cpu_has_rng() && __arm64_rndrrs(v))
return 1;
return 0;
@@ -121,40 +129,4 @@ static inline bool __init __early_cpu_has_rndr(void)
return (ftr >> ID_AA64ISAR0_EL1_RNDR_SHIFT) & 0xf;
}
-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;
-
- 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) {
- 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 1;
-
- return 0;
-}
-#define arch_get_random_seed_longs_early arch_get_random_seed_longs_early
-
#endif /* _ASM_ARCHRANDOM_H */
diff --git a/arch/arm64/include/asm/stackprotector.h b/arch/arm64/include/asm/stackprotector.h
index 33f1bb453150..ae3ad80f51fe 100644
--- a/arch/arm64/include/asm/stackprotector.h
+++ b/arch/arm64/include/asm/stackprotector.h
@@ -13,8 +13,6 @@
#ifndef __ASM_STACKPROTECTOR_H
#define __ASM_STACKPROTECTOR_H
-#include <linux/random.h>
-#include <linux/version.h>
#include <asm/pointer_auth.h>
extern unsigned long __stack_chk_guard;
@@ -28,12 +26,7 @@ extern unsigned long __stack_chk_guard;
static __always_inline void boot_init_stack_canary(void)
{
#if defined(CONFIG_STACKPROTECTOR)
- unsigned long canary;
-
- /* Try to get a semi random initial value. */
- get_random_bytes(&canary, sizeof(canary));
- canary ^= LINUX_VERSION_CODE;
- canary &= CANARY_MASK;
+ unsigned long canary = get_random_canary();
current->stack_canary = canary;
if (!IS_ENABLED(CONFIG_STACKPROTECTOR_PER_TASK))