Seems the attachment was stripped, probably an anti spam measure. So,
I'll just put the text here.
>From 8be9a727727b2a264e55abe8faefb0e5d29b6fd6 Mon Sep 17 00:00:00 2001
From: Fedora Kernel Team <kernel-team@xxxxxxxxxxxxxxxxx>
Date: Sun, 20 Aug 2017 12:16:14 -0700
Subject: [PATCH] use input entropy to reseed crng based on timer and
input entropy pool level
---
drivers/char/random.c | 62
++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 52
insertions(+), 10 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 8ad9270..07da211 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -315,6 +315,13 @@ static int random_read_wakeup_bits = 64;
static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS;
/*
+ * The minimum number of seconds between urandom pool reseeding. We
+ * do this to limit the amount of entropy that can be drained from the
+ * input pool even if there are heavy demands on /dev/urandom.
+ */
+static int random_min_urandom_seed = 60;
+
+/*
* Originally, we used a primitive polynomial of degree .poolwords
* over GF(2). The taps for various sizes are defined below. They
* were chosen to be evenly spaced except for the last tap, which is 1
@@ -399,6 +406,8 @@ static struct poolinfo {
#endif
};
+#define CRNG_RESEED_INTERVAL (random_min_urandom_seed*HZ)
+
/*
* Static global variables
*/
@@ -472,6 +481,7 @@ static ssize_t _extract_entropy(struct
entropy_store *r, void *buf, size_t nbytes, int fips);
static void crng_reseed(struct crng_state *crng, struct entropy_store
*r); +static void crng_entropy_reseed(struct crng_state *crng, struct
entropy_store *r); static void push_to_pool(struct work_struct *work);
static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy;
static __u32 blocking_pool_data[OUTPUT_POOL_WORDS] __latent_entropy;
@@ -702,13 +712,23 @@ static void credit_entropy_bits(struct
entropy_store *r, int nbits) r->entropy_total, _RET_IP_);
if (r == &input_pool) {
- int entropy_bits = entropy_count >> ENTROPY_SHIFT;
-
- if (crng_init < 2 && entropy_bits >= 128) {
- crng_reseed(&primary_crng, r);
- entropy_bits = r->entropy_count >>
ENTROPY_SHIFT;
+ int entropy_bits;
+ if (crng_init < 2)
+ { entropy_bits = entropy_count >> ENTROPY_SHIFT;
+ if (entropy_bits >= 128)
+ { crng_reseed(&primary_crng, r);
+ entropy_bits = r->entropy_count >> ENTROPY_SHIFT;
+ }
+ }
+ else if (crng_init == 2)
+ { if (r->entropy_count >= 4000)
+ { struct crng_state *crng = &primary_crng;
+ if (time_after(jiffies, crng->init_time +
CRNG_RESEED_INTERVAL))
+ { crng_entropy_reseed(crng, r);
+ entropy_bits = r->entropy_count - 256;
+ }
+ }
}
-
/* should we wake readers? */
if (entropy_bits >= random_read_wakeup_bits) {
wake_up_interruptible(&random_read_wait);
@@ -721,7 +741,6 @@ static void credit_entropy_bits(struct
entropy_store *r, int nbits) r->initialized &&
r->entropy_total >= 2*random_read_wakeup_bits) {
struct entropy_store *other = &blocking_pool;
-
if (other->entropy_count <=
3 * other->poolinfo->poolfracbits / 4) {
schedule_work(&other->push_work);
@@ -751,8 +770,6 @@ static int credit_entropy_bits_safe(struct
entropy_store *r, int nbits) *
*********************************************************************/
-#define CRNG_RESEED_INTERVAL (300*HZ)
-
static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
#ifdef CONFIG_NUMA
@@ -851,6 +868,32 @@ static void crng_reseed(struct crng_state *crng,
struct entropy_store *r) }
}
+static void crng_entropy_reseed(struct crng_state *crng, struct
entropy_store *r) +{
+ unsigned long flags;
+ int i, num;
+ union {
+ __u8 block[CHACHA20_BLOCK_SIZE];
+ __u32 key[8];
+ } buf;
+
+ if (r) {
+ num = extract_entropy(r, &buf, 32, 16, 0);
+ if (num == 0)
+ return;
+ }
+ spin_lock_irqsave(&primary_crng.lock, flags);
+ for (i = 0; i < 8; i++) {
+ crng->state[i+4] ^= buf.key[i];
+ }
+ memzero_explicit(&buf, sizeof(buf));
+ crng->init_time = jiffies;
+ spin_unlock_irqrestore(&primary_crng.lock, flags);
+ if (crng == &primary_crng && crng_init == 2) {
+ pr_notice("random: crng entropy reseed done\n");
+ }
+}
+
static void _extract_crng(struct crng_state *crng,
__u8 out[CHACHA20_BLOCK_SIZE])
{
@@ -1942,7 +1985,6 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf,
size_t, count, static int min_read_thresh = 8, min_write_thresh;
static int max_read_thresh = OUTPUT_POOL_WORDS * 32;
static int max_write_thresh = INPUT_POOL_WORDS * 32;
-static int random_min_urandom_seed = 60;
static char sysctl_bootid[16];
/*
--
2.9.5
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