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linuxkm/lkcapi_sha_glue.c:

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* in get_drbg(), call local_bh_disable() for the crypto_default_rng, and in put_drbg(), call local_bh_enable() if needed.
* re-gate migrate_disable() and migrate_enable() so they're called for any SMP kernel >= 5.7, regardless of CONFIG_PREEMPT_COUNT.
* in get_drbg_n(), if the caller can't sleep, return immediately if the requested DRBG is busy, to avoid priority inversions and deadlocks.
This commit is contained in:
Daniel Pouzzner
2025-12-10 20:33:48 -06:00
parent b69ce5a568
commit fe33bb9bd9
1 changed files with 13 additions and 12 deletions
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25
linuxkm/lkcapi_sha_glue.c
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@@ -1073,17 +1073,17 @@ static inline struct wc_rng_inst *get_drbg(struct crypto_rng *tfm) {
return NULL;
}
#if defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT_COUNT) && \
(LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0))
if (tfm == crypto_default_rng) {
#if defined(CONFIG_SMP) && (LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0))
migrate_disable(); /* this actually makes irq_count() nonzero, so that
* DISABLE_VECTOR_REGISTERS() is superfluous, but
* don't depend on that.
*/
#endif
local_bh_disable();
new_lock_value = 2;
}
else
#endif
{
new_lock_value = 1;
}
@@ -1104,7 +1104,9 @@ static inline struct wc_rng_inst *get_drbg(struct crypto_rng *tfm) {
}
/* get_drbg_n() is used by bulk seed, mix-in, and reseed operations. It expects
* the caller to be able to wait until the requested DRBG is available.
* the caller to be able to wait until the requested DRBG is available. If the
* caller can't sleep and the requested DRBG is busy, it returns immediately --
* this avoids priority inversions and deadlocks.
*/
static inline struct wc_rng_inst *get_drbg_n(struct wc_linuxkm_drbg_ctx *ctx, int n) {
int can_sleep = (preempt_count() == 0);
@@ -1119,23 +1121,22 @@ static inline struct wc_rng_inst *get_drbg_n(struct wc_linuxkm_drbg_ctx *ctx, in
cond_resched();
}
else
cpu_relax();
return NULL;
}
__builtin_unreachable();
}
static inline void put_drbg(struct wc_rng_inst *drbg) {
#if defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT_COUNT) && \
(LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0))
int migration_disabled = (drbg->lock == 2);
#endif
__atomic_store_n(&(drbg->lock),0,__ATOMIC_RELEASE);
#if defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT_COUNT) && \
(LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0))
if (migration_disabled)
if (migration_disabled) {
local_bh_enable();
#if defined(CONFIG_SMP) && (LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0))
migrate_enable();
#endif
#endif
}
}
static int wc_linuxkm_drbg_generate(struct crypto_rng *tfm,