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linuxkm/linuxkm_wc_port.h: in malloc/realloc, use GFP_KERNEL if it's safe to sleep;

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linuxkm/lkcapi_sha_glue.c:

* in wc_linuxkm_drbg_init_tfm(), sleep if it's safe, and observe a wc_linuxkm_drbg_init_tfm_disable_vector_registers flag;

* in wc_crng_reseed(), preemptively execute the reseed if it's safe to sleep;

* in wc_linuxkm_drbg_startup(), in LINUXKM_DRBG_GET_RANDOM_BYTES section, add reseed test sequence if defined(DEBUG_DRBG_RESEEDS).
This commit is contained in:
Daniel Pouzzner
2025-07-02 16:46:27 -05:00
parent 0160af0a0d
commit dd69d56e33
2 changed files with 66 additions and 27 deletions
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6
linuxkm/linuxkm_wc_port.h
View File

@ -1085,14 +1085,14 @@
_alloc_sz; \
})
#ifdef HAVE_KVMALLOC
#define malloc(size) kvmalloc_node(WC_LINUXKM_ROUND_UP_P_OF_2(size), GFP_ATOMIC, NUMA_NO_NODE)
#define malloc(size) kvmalloc_node(WC_LINUXKM_ROUND_UP_P_OF_2(size), (preempt_count() == 0 ? GFP_KERNEL : GFP_ATOMIC), NUMA_NO_NODE)
#define free(ptr) kvfree(ptr)
void *lkm_realloc(void *ptr, size_t newsize);
#define realloc(ptr, newsize) lkm_realloc(ptr, WC_LINUXKM_ROUND_UP_P_OF_2(newsize))
#else
#define malloc(size) kmalloc(WC_LINUXKM_ROUND_UP_P_OF_2(size), GFP_ATOMIC)
#define malloc(size) kmalloc(WC_LINUXKM_ROUND_UP_P_OF_2(size), (preempt_count() == 0 ? GFP_KERNEL : GFP_ATOMIC))
#define free(ptr) kfree(ptr)
#define realloc(ptr, newsize) krealloc(ptr, WC_LINUXKM_ROUND_UP_P_OF_2(newsize), GFP_ATOMIC)
#define realloc(ptr, newsize) krealloc(ptr, WC_LINUXKM_ROUND_UP_P_OF_2(newsize), (preempt_count() == 0 ? GFP_KERNEL : GFP_ATOMIC))
#endif
#ifndef static_assert

87
linuxkm/lkcapi_sha_glue.c
View File

@ -966,11 +966,15 @@ static inline void wc_linuxkm_drbg_ctx_clear(struct wc_linuxkm_drbg_ctx * ctx)
return;
}
static volatile int wc_linuxkm_drbg_init_tfm_disable_vector_registers = 0;
static int wc_linuxkm_drbg_init_tfm(struct crypto_tfm *tfm)
{
struct wc_linuxkm_drbg_ctx *ctx = (struct wc_linuxkm_drbg_ctx *)crypto_tfm_ctx(tfm);
unsigned int i;
int ret;
int need_reenable_vec = 0;
int can_sleep = (preempt_count() == 0);
ctx->rngs = (struct wc_rng_inst *)malloc(sizeof(*ctx->rngs) * nr_cpu_ids);
if (! ctx->rngs)
@ -979,12 +983,18 @@ static int wc_linuxkm_drbg_init_tfm(struct crypto_tfm *tfm)
for (i = 0; i < nr_cpu_ids; ++i) {
ctx->rngs[i].lock = 0;
if (wc_linuxkm_drbg_init_tfm_disable_vector_registers)
need_reenable_vec = (DISABLE_VECTOR_REGISTERS() == 0);
ret = wc_InitRng(&ctx->rngs[i].rng);
if (need_reenable_vec)
REENABLE_VECTOR_REGISTERS();
if (ret != 0) {
pr_warn_once("WARNING: wc_InitRng returned %d\n",ret);
ret = -EINVAL;
break;
}
if (can_sleep)
cond_resched();
}
if (ret != 0) {
@ -1349,7 +1359,7 @@ static ssize_t wc_extract_crng_user(void __user *buf, size_t nbytes) {
ForceZero(block, sizeof(block));
if (total_copied == 0) {
if ((total_copied == 0) && (ret == 0)) {
ret = -ECANCELED;
}
@ -1391,6 +1401,7 @@ static int wc_mix_pool_bytes(const void *buf, size_t len) {
static int wc_crng_reseed(void) {
struct wc_linuxkm_drbg_ctx *ctx = get_default_drbg_ctx();
int n;
int can_sleep = (preempt_count() == 0);
if (! ctx)
return -EFAULT;
@ -1398,11 +1409,17 @@ static int wc_crng_reseed(void) {
for (n = nr_cpu_ids - 1; n >= 0; --n) {
struct wc_rng_inst *drbg = get_drbg_n(ctx, n);
((struct DRBG_internal *)drbg->rng.drbg)->reseedCtr = WC_RESEED_INTERVAL;
/* don't actually reseed now -- running the memory entropy generator for
* all of the DRBGs can take so long that it triggers "rcu: INFO:
* rcu_sched self-detected stall on CPU".
*/
put_drbg(drbg);
if (can_sleep) {
byte scratch[4];
int need_reenable_vec = (DISABLE_VECTOR_REGISTERS() == 0);
int ret = wc_RNG_GenerateBlock(&drbg->rng, scratch, (word32)sizeof(scratch));
if (need_reenable_vec)
REENABLE_VECTOR_REGISTERS();
if (ret != 0)
pr_err("ERROR: wc_crng_reseed() wc_RNG_GenerateBlock() for DRBG #%d returned %d.", n, ret);
put_drbg(drbg);
cond_resched();
}
}
return 0;
@ -1712,22 +1729,19 @@ static int wc_linuxkm_drbg_startup(void)
WOLFKM_INSTALL_NOTICE(wc_linuxkm_drbg);
#ifdef LINUXKM_LKCAPI_REGISTER_HASH_DRBG_DEFAULT
ret = crypto_del_default_rng();
if (ret) {
pr_err("ERROR: crypto_del_default_rng returned %d", ret);
return ret;
}
/* for the default RNG, make sure we don't cache an underlying SHA256
* method that uses vector insns (forbidden from irq handlers).
*/
ret = DISABLE_VECTOR_REGISTERS();
if (ret != 0) {
pr_err("ERROR: DISABLE_VECTOR_REGISTERS() returned %d", ret);
return -EINVAL;
wc_linuxkm_drbg_init_tfm_disable_vector_registers = 1;
ret = crypto_del_default_rng();
if (ret) {
wc_linuxkm_drbg_init_tfm_disable_vector_registers = 0;
pr_err("ERROR: crypto_del_default_rng returned %d", ret);
return ret;
}
ret = crypto_get_default_rng();
REENABLE_VECTOR_REGISTERS();
wc_linuxkm_drbg_init_tfm_disable_vector_registers = 0;
if (ret) {
pr_err("ERROR: crypto_get_default_rng returned %d", ret);
@ -1747,18 +1761,17 @@ static int wc_linuxkm_drbg_startup(void)
return -EINVAL;
}
if (strcmp(crypto_tfm_alg_driver_name(&crypto_default_rng->base), wc_linuxkm_drbg.base.cra_driver_name) == 0) {
crypto_put_default_rng();
wc_linuxkm_drbg_default_instance_registered = 1;
pr_info("%s registered as systemwide default stdrng.", wc_linuxkm_drbg.base.cra_driver_name);
pr_info("libwolfssl: to unload module, first echo 1 > /sys/module/libwolfssl/deinstall_algs");
}
else {
if (crypto_default_rng->base.__crt_alg->cra_init != wc_linuxkm_drbg_init_tfm) {
pr_err("ERROR: %s NOT registered as systemwide default stdrng -- found \"%s\".", wc_linuxkm_drbg.base.cra_driver_name, crypto_tfm_alg_driver_name(&crypto_default_rng->base));
crypto_put_default_rng();
return -EINVAL;
}
crypto_put_default_rng();
wc_linuxkm_drbg_default_instance_registered = 1;
pr_info("%s registered as systemwide default stdrng.", wc_linuxkm_drbg.base.cra_driver_name);
pr_info("libwolfssl: to unload module, first echo 1 > /sys/module/libwolfssl/deinstall_algs");
#ifdef LINUXKM_DRBG_GET_RANDOM_BYTES
#ifdef WOLFSSL_LINUXKM_HAVE_GET_RANDOM_CALLBACKS
@ -1801,6 +1814,32 @@ static int wc_linuxkm_drbg_startup(void)
#error LINUXKM_DRBG_GET_RANDOM_BYTES missing installation calls.
#endif
#ifdef DEBUG_DRBG_RESEEDS
{
byte scratch[4];
ret = wc__get_random_bytes(scratch, sizeof(scratch));
if (ret != 0) {
pr_err("ERROR: wc__get_random_bytes() returned %d", ret);
return -EINVAL;
}
ret = wc_mix_pool_bytes(scratch, sizeof(scratch));
if (ret != 0) {
pr_err("ERROR: wc_mix_pool_bytes() returned %d", ret);
return -EINVAL;
}
ret = wc_crng_reseed();
if (ret != 0) {
pr_err("ERROR: wc_crng_reseed() returned %d", ret);
return -EINVAL;
}
ret = wc__get_random_bytes(scratch, sizeof(scratch));
if (ret != 0) {
pr_err("ERROR: wc__get_random_bytes() returned %d", ret);
return -EINVAL;
}
}
#endif
#endif /* LINUXKM_DRBG_GET_RANDOM_BYTES */
#endif /* LINUXKM_LKCAPI_REGISTER_HASH_DRBG_DEFAULT */