This is a note to let you know that I've just added the patch titled
random: always wake up entropy writers after extraction
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
random-always-wake-up-entropy-writers-after-extraction.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Fri Jun 17 08:58:56 AM CEST 2022
From: "Jason A. Donenfeld" <Jason@xxxxxxxxx>
Date: Sat, 5 Feb 2022 14:00:58 +0100
Subject: random: always wake up entropy writers after extraction
From: "Jason A. Donenfeld" <Jason@xxxxxxxxx>
commit 489c7fc44b5740d377e8cfdbf0851036e493af00 upstream.
Now that POOL_BITS == POOL_MIN_BITS, we must unconditionally wake up
entropy writers after every extraction. Therefore there's no point of
write_wakeup_threshold, so we can move it to the dustbin of unused
compatibility sysctls. While we're at it, we can fix a small comparison
where we were waking up after <= min rather than < min.
Cc: Theodore Ts'o <tytso@xxxxxxx>
Suggested-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Reviewed-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Reviewed-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
Documentation/sysctl/kernel.txt | 44 ++++++++++++++++++++++++++++++++++++++--
drivers/char/random.c | 36 ++++++++++++--------------------
2 files changed, 56 insertions(+), 24 deletions(-)
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -821,9 +821,49 @@ The kernel command line parameter printk
a one-time setting until next reboot: once set, it cannot be changed by
this sysctl interface anymore.
-==============================================================
+pty
+===
-randomize_va_space:
+See Documentation/filesystems/devpts.rst.
+
+
+random
+======
+
+This is a directory, with the following entries:
+
+* ``boot_id``: a UUID generated the first time this is retrieved, and
+ unvarying after that;
+
+* ``entropy_avail``: the pool's entropy count, in bits;
+
+* ``poolsize``: the entropy pool size, in bits;
+
+* ``urandom_min_reseed_secs``: obsolete (used to determine the minimum
+ number of seconds between urandom pool reseeding). This file is
+ writable for compatibility purposes, but writing to it has no effect
+ on any RNG behavior.
+
+* ``uuid``: a UUID generated every time this is retrieved (this can
+ thus be used to generate UUIDs at will);
+
+* ``write_wakeup_threshold``: when the entropy count drops below this
+ (as a number of bits), processes waiting to write to ``/dev/random``
+ are woken up. This file is writable for compatibility purposes, but
+ writing to it has no effect on any RNG behavior.
+
+If ``drivers/char/random.c`` is built with ``ADD_INTERRUPT_BENCH``
+defined, these additional entries are present:
+
+* ``add_interrupt_avg_cycles``: the average number of cycles between
+ interrupts used to feed the pool;
+
+* ``add_interrupt_avg_deviation``: the standard deviation seen on the
+ number of cycles between interrupts used to feed the pool.
+
+
+randomize_va_space
+==================
This option can be used to select the type of process address
space randomization that is used in the system, for architectures
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -296,12 +296,6 @@ enum {
*/
static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
static struct fasync_struct *fasync;
-/*
- * If the entropy count falls under this number of bits, then we
- * should wake up processes which are selecting or polling on write
- * access to /dev/random.
- */
-static int random_write_wakeup_bits = POOL_MIN_BITS;
static DEFINE_SPINLOCK(random_ready_list_lock);
static LIST_HEAD(random_ready_list);
@@ -739,10 +733,8 @@ static void crng_reseed(struct crng_stat
return;
} while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
extract_entropy(buf.key, sizeof(buf.key));
- if (random_write_wakeup_bits) {
- wake_up_interruptible(&random_write_wait);
- kill_fasync(&fasync, SIGIO, POLL_OUT);
- }
+ wake_up_interruptible(&random_write_wait);
+ kill_fasync(&fasync, SIGIO, POLL_OUT);
} else {
_extract_crng(&primary_crng, buf.block);
_crng_backtrack_protect(&primary_crng, buf.block,
@@ -1471,7 +1463,7 @@ static __poll_t random_poll(struct file
mask = 0;
if (crng_ready())
mask |= EPOLLIN | EPOLLRDNORM;
- if (input_pool.entropy_count < random_write_wakeup_bits)
+ if (input_pool.entropy_count < POOL_MIN_BITS)
mask |= EPOLLOUT | EPOLLWRNORM;
return mask;
}
@@ -1556,7 +1548,10 @@ static long random_ioctl(struct file *f,
*/
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- input_pool.entropy_count = 0;
+ if (xchg(&input_pool.entropy_count, 0)) {
+ wake_up_interruptible(&random_write_wait);
+ kill_fasync(&fasync, SIGIO, POLL_OUT);
+ }
return 0;
case RNDRESEEDCRNG:
if (!capable(CAP_SYS_ADMIN))
@@ -1631,9 +1626,9 @@ SYSCALL_DEFINE3(getrandom, char __user *
#include <linux/sysctl.h>
-static int min_write_thresh;
-static int max_write_thresh = POOL_BITS;
static int random_min_urandom_seed = 60;
+static int random_write_wakeup_bits = POOL_MIN_BITS;
+static int sysctl_poolsize = POOL_BITS;
static char sysctl_bootid[16];
/*
@@ -1672,7 +1667,6 @@ static int proc_do_uuid(struct ctl_table
return proc_dostring(&fake_table, write, buffer, lenp, ppos);
}
-static int sysctl_poolsize = POOL_BITS;
extern struct ctl_table random_table[];
struct ctl_table random_table[] = {
{
@@ -1694,9 +1688,7 @@ struct ctl_table random_table[] = {
.data = &random_write_wakeup_bits,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = &min_write_thresh,
- .extra2 = &max_write_thresh,
+ .proc_handler = proc_dointvec,
},
{
.procname = "urandom_min_reseed_secs",
@@ -1877,13 +1869,13 @@ void add_hwgenerator_randomness(const ch
}
/* Throttle writing if we're above the trickle threshold.
- * We'll be woken up again once below random_write_wakeup_thresh,
- * when the calling thread is about to terminate, or once
- * CRNG_RESEED_INTERVAL has lapsed.
+ * We'll be woken up again once below POOL_MIN_BITS, when
+ * the calling thread is about to terminate, or once
+ * CRNG_RESEED_INTERVAL has elapsed.
*/
wait_event_interruptible_timeout(random_write_wait,
!system_wq || kthread_should_stop() ||
- input_pool.entropy_count <= random_write_wakeup_bits,
+ input_pool.entropy_count < POOL_MIN_BITS,
CRNG_RESEED_INTERVAL);
mix_pool_bytes(buffer, count);
credit_entropy_bits(entropy);
Patches currently in stable-queue which might be from Jason@xxxxxxxxx are
queue-4.19/random-do-not-take-pool-spinlock-at-boot.patch
queue-4.19/random-remove-kernel.random.read_wakeup_threshold.patch
queue-4.19/random-simplify-arithmetic-function-flow-in-account.patch
queue-4.19/random-order-timer-entropy-functions-below-interrupt-functions.patch
queue-4.19/random-introduce-drain_entropy-helper-to-declutter-crng_reseed.patch
queue-4.19/random-fix-locking-in-crng_fast_load.patch
queue-4.19/random-cleanup-uuid-handling.patch
queue-4.19/random-group-userspace-read-write-functions.patch
queue-4.19/random-make-credit_entropy_bits-always-safe.patch
queue-4.19/latent_entropy-avoid-build-error-when-plugin-cflags-are-not-set.patch
queue-4.19/revert-hwrng-core-freeze-khwrng-thread-during-suspend.patch
queue-4.19/drivers-char-random.c-make-primary_crng-static.patch
queue-4.19/random-do-not-re-init-if-crng_reseed-completes-before-primary-init.patch
queue-4.19/random-use-proper-jiffies-comparison-macro.patch
queue-4.19/init-call-time_init-before-rand_initialize.patch
queue-4.19/random-split-primary-secondary-crng-init-paths.patch
queue-4.19/random-pull-add_hwgenerator_randomness-declaration-into-random.h.patch
queue-4.19/random-unify-early-init-crng-load-accounting.patch
queue-4.19/drivers-char-random.c-remove-unused-stuct-poolinfo-poolbits.patch
queue-4.19/random-use-blake2s-instead-of-sha1-in-extraction.patch
queue-4.19/random-convert-to-using-fops-write_iter.patch
queue-4.19/random-initialize-chacha20-constants-with-correct-endianness.patch
queue-4.19/random-remove-incomplete-last_data-logic.patch
queue-4.19/random-group-entropy-extraction-functions.patch
queue-4.19/random-add-proper-spdx-header.patch
queue-4.19/linux-random.h-remove-arch_has_random-arch_has_random_seed.patch
queue-4.19/random-rewrite-header-introductory-comment.patch
queue-4.19/random-make-dev-random-be-almost-like-dev-urandom.patch
queue-4.19/random-remove-ifdef-d-out-interrupt-bench.patch
queue-4.19/um-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/lib-crypto-sha1-re-roll-loops-to-reduce-code-size.patch
queue-4.19/random-tie-batched-entropy-generation-to-base_crng-generation.patch
queue-4.19/sparc-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/random-use-linear-min-entropy-accumulation-crediting.patch
queue-4.19/random-remove-batched-entropy-locking.patch
queue-4.19/xtensa-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/powerpc-remove-arch_has_random-arch_has_random_seed.patch
queue-4.19/fdt-add-support-for-rng-seed.patch
queue-4.19/random-continually-use-hwgenerator-randomness.patch
queue-4.19/random-access-input_pool_data-directly-rather-than-through-pointer.patch
queue-4.19/random-add-arch_get_random_-long_early.patch
queue-4.19/random-inline-leaves-of-rand_initialize.patch
queue-4.19/random-cleanup-poolinfo-abstraction.patch
queue-4.19/random-wire-up-fops-splice_-read-write-_iter.patch
queue-4.19/random-handle-latent-entropy-and-command-line-from-random_init.patch
queue-4.19/random-remove-use_input_pool-parameter-from-crng_reseed.patch
queue-4.19/random-credit-architectural-init-the-exact-amount.patch
queue-4.19/ia64-define-get_cycles-macro-for-arch-override.patch
queue-4.19/random-replace-custom-notifier-chain-with-standard-one.patch
queue-4.19/random-support-freezable-kthreads-in-add_hwgenerator_randomness.patch
queue-4.19/random-document-get_random_int-family.patch
queue-4.19/random-remove-the-blocking-pool.patch
queue-4.19/random-avoid-initializing-twice-in-credit-race.patch
queue-4.19/random-avoid-warnings-for-config_numa-builds.patch
queue-4.19/crypto-drbg-add-fips-140-2-ctrng-for-noise-source.patch
queue-4.19/random-mark-bootloader-randomness-code-as-__init.patch
queue-4.19/random-zero-buffer-after-reading-entropy-from-userspace.patch
queue-4.19/random-remove-whitespace-and-reorder-includes.patch
queue-4.19/random-ignore-grnd_random-in-getentropy-2.patch
queue-4.19/random-clear-fast-pool-crng-and-batches-in-cpuhp-bring-up.patch
queue-4.19/random-document-add_hwgenerator_randomness-with-other-input-functions.patch
queue-4.19/random-fix-typo-in-add_timer_randomness.patch
queue-4.19/random-do-crng-pre-init-loading-in-worker-rather-than-irq.patch
queue-4.19/powerpc-use-bool-in-archrandom.h.patch
queue-4.19/random-do-not-split-fast-init-input-in-add_hwgenerator_randomness.patch
queue-4.19/timekeeping-add-raw-clock-fallback-for-random_get_entropy.patch
queue-4.19/random-early-initialization-of-chacha-constants.patch
queue-4.19/crypto-drbg-prepare-for-more-fine-grained-tracking-of-seeding-state.patch
queue-4.19/random-delete-code-to-pull-data-into-pools.patch
queue-4.19/crypto-drbg-always-try-to-free-jitter-rng-instance.patch
queue-4.19/random-simplify-entropy-debiting.patch
queue-4.19/random-don-t-reset-crng_init_cnt-on-urandom_read.patch
queue-4.19/random-skip-fast_init-if-hwrng-provides-large-chunk-of-entropy.patch
queue-4.19/random-use-siphash-as-interrupt-entropy-accumulator.patch
queue-4.19/random-avoid-checking-crng_ready-twice-in-random_init.patch
queue-4.19/random-fix-soft-lockup-when-trying-to-read-from-an-uninitialized-blocking-pool.patch
queue-4.19/random-group-sysctl-functions.patch
queue-4.19/random-don-t-let-644-read-only-sysctls-be-written-to.patch
queue-4.19/random-document-crng_fast_key_erasure-destination-possibility.patch
queue-4.19/random-only-wake-up-writers-after-zap-if-threshold-was-passed.patch
queue-4.19/random-use-wait_event_freezable-in-add_hwgenerator_randomness.patch
queue-4.19/random-check-for-signal-and-try-earlier-when-generating-entropy.patch
queue-4.19/random-check-for-signals-every-page_size-chunk-of-dev-random.patch
queue-4.19/arm-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/random-absorb-fast-pool-into-input-pool-after-fast-load.patch
queue-4.19/random-give-sysctl_random_min_urandom_seed-a-more-sensible-value.patch
queue-4.19/crypto-blake2s-generic-c-library-implementation-and-selftest.patch
queue-4.19/random-cleanup-fractional-entropy-shift-constants.patch
queue-4.19/random-use-rdseed-instead-of-rdrand-in-entropy-extraction.patch
queue-4.19/random-move-rand_initialize-earlier.patch
queue-4.19/random-don-t-wake-crng_init_wait-when-crng_init-1.patch
queue-4.19/random-add-a-urandom_read_nowait-for-random-apis-that-don-t-warn.patch
queue-4.19/random-do-not-sign-extend-bytes-for-rotation-when-mixing.patch
queue-4.19/random-move-initialization-functions-out-of-hot-pages.patch
queue-4.19/random-remove-dead-code-left-over-from-blocking-pool.patch
queue-4.19/drivers-char-random.c-constify-poolinfo_table.patch
queue-4.19/crypto-drbg-track-whether-drbg-was-seeded-with-rng_is_initialized.patch
queue-4.19/random-use-computational-hash-for-entropy-extraction.patch
queue-4.19/random-add-and-use-pr_fmt.patch
queue-4.19/random-round-robin-registers-as-ulong-not-u32.patch
queue-4.19/random-always-wake-up-entropy-writers-after-extraction.patch
queue-4.19/s390-remove-arch_has_random-arch_has_random_seed.patch
queue-4.19/random-do-not-xor-rdrand-when-writing-into-dev-random.patch
queue-4.19/crypto-drbg-make-reseeding-from-get_random_bytes-synchronous.patch
queue-4.19/random-convert-to-entropy_bits-for-better-code-readability.patch
queue-4.19/char-random-add-a-newline-at-the-end-of-the-file.patch
queue-4.19/random-move-randomize_page-into-mm-where-it-belongs.patch
queue-4.19/random-only-call-crng_finalize_init-for-primary_crng.patch
queue-4.19/random-cleanup-integer-types.patch
queue-4.19/random-re-add-removed-comment-about-get_random_-u32-u64-reseeding.patch
queue-4.19/random-unify-cycles_t-and-jiffies-usage-and-types.patch
queue-4.19/random-insist-on-random_get_entropy-existing-in-order-to-simplify.patch
queue-4.19/random-group-initialization-wait-functions.patch
queue-4.19/linux-random.h-mark-config_arch_random-functions-__must_check.patch
queue-4.19/random-remove-unused-extract_entropy-reserved-argument.patch
queue-4.19/random-check-for-signal_pending-outside-of-need_resched-check.patch
queue-4.19/random-access-primary_pool-directly-rather-than-through-pointer.patch
queue-4.19/random-fix-sysctl-documentation-nits.patch
queue-4.19/random-remove-unused-tracepoints.patch
queue-4.19/random-only-read-from-dev-random-after-its-pool-has-received-128-bits.patch
queue-4.19/nios2-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/random-treat-bootloader-trust-toggle-the-same-way-as-cpu-trust-toggle.patch
queue-4.19/random-make-consistent-usage-of-crng_ready.patch
queue-4.19/lib-crypto-blake2s-move-hmac-construction-into-wireguard.patch
queue-4.19/parisc-define-get_cycles-macro-for-arch-override.patch
queue-4.19/x86-tsc-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/random-add-grnd_insecure-to-return-best-effort-non-cryptographic-bytes.patch
queue-4.19/crypto-drbg-move-dynamic-reseed_threshold-adjustments-to-__drbg_seed.patch
queue-4.19/random-check-for-signals-after-page-of-pool-writes.patch
queue-4.19/random-make-random_get_entropy-return-an-unsigned-long.patch
queue-4.19/random-check-for-crng_init-0-in-add_device_randomness.patch
queue-4.19/random-remove-unnecessary-unlikely.patch
queue-4.19/random-defer-fast-pool-mixing-to-worker.patch
queue-4.19/random-harmonize-crng-init-done-messages.patch
queue-4.19/crypto-blake2s-include-linux-bug.h-instead-of-asm-bug.h.patch
queue-4.19/random-use-static-branch-for-crng_ready.patch
queue-4.19/random-rather-than-entropy_store-abstraction-use-global.patch
queue-4.19/random-remove-extern-from-functions-in-header.patch
queue-4.19/siphash-use-one-source-of-truth-for-siphash-permutations.patch
queue-4.19/random-group-entropy-collection-functions.patch
queue-4.19/random-de-duplicate-input_pool-constants.patch
queue-4.19/random-mix-build-time-latent-entropy-into-pool-at-init.patch
queue-4.19/random-remove-useless-header-comment.patch
queue-4.19/linux-random.h-use-false-with-bool.patch
queue-4.19/maintainers-co-maintain-random.c.patch
queue-4.19/random-remove-outdated-int_max-6-check-in-urandom_read.patch
queue-4.19/m68k-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/alpha-define-get_cycles-macro-for-arch-override.patch
queue-4.19/random-mix-bootloader-randomness-into-pool.patch
queue-4.19/random-remove-some-dead-code-of-poolinfo.patch
queue-4.19/random-do-not-use-batches-when-crng_ready.patch
queue-4.19/crypto-drbg-always-seeded-with-sp800-90b-compliant-noise-source.patch
queue-4.19/s390-define-get_cycles-macro-for-arch-override.patch
queue-4.19/random-do-not-pretend-to-handle-premature-next-security-model.patch
queue-4.19/random-avoid-arch_get_random_seed_long-when-collecting-irq-randomness.patch
queue-4.19/random-use-is_enabled-config_numa-instead-of-ifdefs.patch
queue-4.19/random-avoid-superfluous-call-to-rdrand-in-crng-extraction.patch
queue-4.19/random-use-symbolic-constants-for-crng_init-states.patch
queue-4.19/random-reseed-more-often-immediately-after-booting.patch
queue-4.19/random-ensure-early-rdseed-goes-through-mixer-on-init.patch
queue-4.19/random-deobfuscate-irq-u32-u64-contributions.patch
queue-4.19/random-do-not-use-input-pool-from-hard-irqs.patch
queue-4.19/random-help-compiler-out-with-fast_mix-by-using-simpler-arguments.patch
queue-4.19/revert-random-use-static-branch-for-crng_ready.patch
queue-4.19/random-fix-crash-on-multiple-early-calls-to-add_bootloader_randomness.patch
queue-4.19/random-account-for-arch-randomness-in-bits.patch
queue-4.19/crypto-blake2s-adjust-include-guard-naming.patch
queue-4.19/random-do-not-allow-user-to-keep-crng-key-around-on-stack.patch
queue-4.19/x86-remove-arch_has_random-arch_has_random_seed.patch
queue-4.19/random-remove-ratelimiting-for-in-kernel-unseeded-randomness.patch
queue-4.19/random-remove-unused-irq_flags-argument-from-add_interrupt_randomness.patch
queue-4.19/random-prepend-remaining-pool-constants-with-pool_.patch
queue-4.19/powerpc-define-get_cycles-macro-for-arch-override.patch
queue-4.19/random-remove-unused-output_pool-constants.patch
queue-4.19/mips-use-fallback-for-random_get_entropy-instead-of-just-c0-random.patch
queue-4.19/random-use-hash-function-for-crng_slow_load.patch
queue-4.19/random-fix-typo-in-comments.patch
queue-4.19/random-use-proper-return-types-on-get_random_-int-long-_wait.patch
