Re: [PATCH v27 09/12] LRNG - add Jitter RNG fast noise source
From: Randy Dunlap <hidden>
Date: 2020-01-10 00:25:22
Also in:
linux-crypto, lkml
Hi, On 1/9/20 12:34 AM, Stephan Müller wrote:
--- drivers/char/lrng/Kconfig | 11 +++++ drivers/char/lrng/Makefile | 1 + drivers/char/lrng/lrng_jent.c | 87 +++++++++++++++++++++++++++++++++++ 3 files changed, 99 insertions(+) create mode 100644 drivers/char/lrng/lrng_jent.c
quoted hunk ↗ jump to hunk
diff --git a/drivers/char/lrng/lrng_jent.c b/drivers/char/lrng/lrng_jent.c new file mode 100644 index 000000000000..97c0d192e9c8 --- /dev/null +++ b/drivers/char/lrng/lrng_jent.c@@ -0,0 +1,87 @@ +// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause +/* + * LRNG Fast Noise Source: Jitter RNG + * + * Copyright (C) 2016 - 2020, Stephan Mueller <smueller@chronox.de> + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/types.h> +#include <crypto/internal/jitterentropy.h> + +#include "lrng_internal.h" + +/* + * Estimated entropy of data is a 16th of LRNG_DRNG_SECURITY_STRENGTH_BITS. + * Albeit a full entropy assessment is provided for the noise source indicating + * that it provides high entropy rates and considering that it deactivates + * when it detects insufficient hardware, the chosen under estimation of + * entropy is considered to be acceptable to all reviewers. + */ +static u32 jitterrng = LRNG_DRNG_SECURITY_STRENGTH_BITS>>4; +module_param(jitterrng, uint, 0644); +MODULE_PARM_DESC(jitterrng, "Entropy in bits of 256 data bits from Jitter " + "RNG noise source"); + +/** + * Get Jitter RNG entropy + * + * @outbuf buffer to store entropy + * @outbuflen length of buffer + * @return > 0 on success where value provides the added entropy in bits + * 0 if no fast source was available + */
Don't begin the comment block with /** or convert it to Linux kernel-doc notation format.
+static struct rand_data *lrng_jent_state;
+
+u32 lrng_get_jent(u8 *outbuf, unsigned int outbuflen)
+{
+ int ret;
+ u32 ent_bits = jitterrng;
+ unsigned long flags;
+ static DEFINE_SPINLOCK(lrng_jent_lock);
+ static int lrng_jent_initialized = 0;
+
+ spin_lock_irqsave(&lrng_jent_lock, flags);
+
+ if (!ent_bits || (lrng_jent_initialized == -1)) {
+ spin_unlock_irqrestore(&lrng_jent_lock, flags);
+ return 0;
+ }
+
+ if (!lrng_jent_initialized) {
+ lrng_jent_state = jent_lrng_entropy_collector();
+ if (!lrng_jent_state) {
+ jitterrng = 0;
+ lrng_jent_initialized = -1;
+ spin_unlock_irqrestore(&lrng_jent_lock, flags);
+ pr_info("Jitter RNG unusable on current system\n");
+ return 0;
+ }
+ lrng_jent_initialized = 1;
+ pr_debug("Jitter RNG working on current system\n");
+ }
+ ret = jent_read_entropy(lrng_jent_state, outbuf, outbuflen);
+ spin_unlock_irqrestore(&lrng_jent_lock, flags);
+
+ if (ret) {
+ pr_debug("Jitter RNG failed with %d\n", ret);
+ return 0;
+ }
+
+ /* Obtain entropy statement */
+ if (outbuflen != LRNG_DRNG_SECURITY_STRENGTH_BYTES)
+ ent_bits = (ent_bits * outbuflen<<3) /
+ LRNG_DRNG_SECURITY_STRENGTH_BITS;
+ /* Cap entropy to buffer size in bits */
+ ent_bits = min_t(u32, ent_bits, outbuflen<<3);
+ pr_debug("obtained %u bits of entropy from Jitter RNG noise source\n",
+ ent_bits);
+
+ return ent_bits;
+}
+
+u32 lrng_jent_entropylevel(void)
+{
+ return min_t(u32, jitterrng, LRNG_DRNG_SECURITY_STRENGTH_BITS);
+}thanks. -- ~Randy