[PATCH 4.9 097/264] random: remove incomplete last_data logic

Greg Kroah-Hartman
2022-06-23T16:56:22Z

From: "Jason A. Donenfeld" <Jason@zx2c4.com>

commit a4bfa9b31802c14ff5847123c12b98d5e36b3985 upstream.

There were a few things added under the "if (fips_enabled)" banner,
which never really got completed, and the FIPS people anyway are
choosing a different direction. Rather than keep around this halfbaked
code, get rid of it so that we can focus on a single design of the RNG
rather than two designs.

Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 40 ++++------------------------------------
1 file changed, 4 insertions(+), 36 deletions(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -337,8 +337,6 @@
#include <linux/spinlock.h>
#include <linux/kthread.h>
#include <linux/percpu.h>
-#include <linux/cryptohash.h>
-#include <linux/fips.h>
#include <linux/ptrace.h>
#include <linux/kmemcheck.h>
#include <linux/workqueue.h>
@@ -519,14 +517,12 @@ struct entropy_store {
u16 add_ptr;
u16 input_rotate;
int entropy_count;
- unsigned int last_data_init:1;
- u8 last_data[EXTRACT_SIZE];
};

static ssize_t extract_entropy(struct entropy_store *r, void *buf,
size_t nbytes, int min, int rsvd);
static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
- size_t nbytes, int fips);
+ size_t nbytes);

static void crng_reseed(struct crng_state *crng, struct entropy_store *r);
static u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy;
@@ -822,7 +818,7 @@ static void crng_initialize_secondary(st

static void __init crng_initialize_primary(struct crng_state *crng)
{
- _extract_entropy(&input_pool, &crng->state[4], sizeof(u32) * 12, 0);
+ _extract_entropy(&input_pool, &crng->state[4], sizeof(u32) * 12);
if (crng_init_try_arch_early(crng) && trust_cpu && crng_init < 2) {
invalidate_batched_entropy();
numa_crng_init();
@@ -1478,22 +1474,13 @@ static void extract_buf(struct entropy_s
}

static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
- size_t nbytes, int fips)
+ size_t nbytes)
{
ssize_t ret = 0, i;
u8 tmp[EXTRACT_SIZE];
- unsigned long flags;

while (nbytes) {
extract_buf(r, tmp);
-
- if (fips) {
- spin_lock_irqsave(&r->lock, flags);
- if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
- panic("Hardware RNG duplicated output!\n");
- memcpy(r->last_data, tmp, EXTRACT_SIZE);
- spin_unlock_irqrestore(&r->lock, flags);
- }
i = min_t(int, nbytes, EXTRACT_SIZE);
memcpy(buf, tmp, i);
nbytes -= i;
@@ -1519,28 +1506,9 @@ static ssize_t _extract_entropy(struct e
static ssize_t extract_entropy(struct entropy_store *r, void *buf,
size_t nbytes, int min, int reserved)
{
- u8 tmp[EXTRACT_SIZE];
- unsigned long flags;
-
- /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
- if (fips_enabled) {
- spin_lock_irqsave(&r->lock, flags);
- if (!r->last_data_init) {
- r->last_data_init = 1;
- spin_unlock_irqrestore(&r->lock, flags);
- trace_extract_entropy(r->name, EXTRACT_SIZE,
- ENTROPY_BITS(r), _RET_IP_);
- extract_buf(r, tmp);
- spin_lock_irqsave(&r->lock, flags);
- memcpy(r->last_data, tmp, EXTRACT_SIZE);
- }
- spin_unlock_irqrestore(&r->lock, flags);
- }
-
trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
nbytes = account(r, nbytes, min, reserved);
-
- return _extract_entropy(r, buf, nbytes, fips_enabled);
+ return _extract_entropy(r, buf, nbytes);
}

#define warn_unseeded_randomness(previous) \