[PATCH v5 02/18] crypto: sun8i-ss: Add support for the PRNG

Corentin Labbe
2020-08-21T13:44:40Z

This patch had support for the PRNG present in the SS.
The output was tested with rngtest without any failure.

Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
---
drivers/crypto/allwinner/Kconfig | 8 +
drivers/crypto/allwinner/sun8i-ss/Makefile | 1 +
.../crypto/allwinner/sun8i-ss/sun8i-ss-core.c | 39 ++++
.../crypto/allwinner/sun8i-ss/sun8i-ss-prng.c | 170 ++++++++++++++++++
drivers/crypto/allwinner/sun8i-ss/sun8i-ss.h | 25 +++
5 files changed, 243 insertions(+)
create mode 100644 drivers/crypto/allwinner/sun8i-ss/sun8i-ss-prng.c

diff --git a/drivers/crypto/allwinner/Kconfig b/drivers/crypto/allwinner/Kconfig
index 96fed786ee75..b5f4f1c090ce 100644
--- a/drivers/crypto/allwinner/Kconfig
+++ b/drivers/crypto/allwinner/Kconfig
@@ -104,3 +104,11 @@ config CRYPTO_DEV_SUN8I_SS_DEBUG
Say y to enable sun8i-ss debug stats.
This will create /sys/kernel/debug/sun8i-ss/stats for displaying
the number of requests per flow and per algorithm.
+
+config CRYPTO_DEV_SUN8I_SS_PRNG
+ bool "Support for Allwinner Security System PRNG"
+ depends on CRYPTO_DEV_SUN8I_SS
+ select CRYPTO_RNG
+ help
+ Select this option if you want to provide kernel-side support for
+ the Pseudo-Random Number Generator found in the Security System.
diff --git a/drivers/crypto/allwinner/sun8i-ss/Makefile b/drivers/crypto/allwinner/sun8i-ss/Makefile
index add7b0543fd5..49f2f912c816 100644
--- a/drivers/crypto/allwinner/sun8i-ss/Makefile
+++ b/drivers/crypto/allwinner/sun8i-ss/Makefile
@@ -1,2 +1,3 @@
obj-$(CONFIG_CRYPTO_DEV_SUN8I_SS) += sun8i-ss.o
sun8i-ss-y += sun8i-ss-core.o sun8i-ss-cipher.o
+sun8i-ss-$(CONFIG_CRYPTO_DEV_SUN8I_SS_PRNG) += sun8i-ss-prng.o
diff --git a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-core.c b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-core.c
index 97012128385f..ae8321f9a1db 100644
--- a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-core.c
+++ b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-core.c
@@ -22,6 +22,7 @@
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>
+#include <crypto/internal/rng.h>
#include <crypto/internal/skcipher.h>

#include "sun8i-ss.h"
@@ -264,6 +265,25 @@ static struct sun8i_ss_alg_template ss_algs[] = {
.decrypt = sun8i_ss_skdecrypt,
}
},
+#ifdef CONFIG_CRYPTO_DEV_SUN8I_SS_PRNG
+{
+ .type = CRYPTO_ALG_TYPE_RNG,
+ .alg.rng = {
+ .base = {
+ .cra_name = "stdrng",
+ .cra_driver_name = "sun8i-ss-prng",
+ .cra_priority = 300,
+ .cra_ctxsize = sizeof(struct sun8i_ss_rng_tfm_ctx),
+ .cra_module = THIS_MODULE,
+ .cra_init = sun8i_ss_prng_init,
+ .cra_exit = sun8i_ss_prng_exit,
+ },
+ .generate = sun8i_ss_prng_generate,
+ .seed = sun8i_ss_prng_seed,
+ .seedsize = PRNG_SEED_SIZE,
+ }
+},
+#endif
};

#ifdef CONFIG_CRYPTO_DEV_SUN8I_SS_DEBUG
@@ -285,6 +305,12 @@ static int sun8i_ss_dbgfs_read(struct seq_file *seq, void *v)
ss_algs[i].alg.skcipher.base.cra_name,
ss_algs[i].stat_req, ss_algs[i].stat_fb);
break;
+ case CRYPTO_ALG_TYPE_RNG:
+ seq_printf(seq, "%s %s %lu %lu\n",
+ ss_algs[i].alg.rng.base.cra_driver_name,
+ ss_algs[i].alg.rng.base.cra_name,
+ ss_algs[i].stat_req, ss_algs[i].stat_bytes);
+ break;
}
}
return 0;
@@ -448,6 +474,14 @@ static int sun8i_ss_register_algs(struct sun8i_ss_dev *ss)
return err;
}
break;
+ case CRYPTO_ALG_TYPE_RNG:
+ err = crypto_register_rng(&ss_algs[i].alg.rng);
+ if (err) {
+ dev_err(ss->dev, "Fail to register %s\n",
+ ss_algs[i].alg.rng.base.cra_name);
+ ss_algs[i].ss = NULL;
+ }
+ break;
default:
ss_algs[i].ss = NULL;
dev_err(ss->dev, "ERROR: tried to register an unknown algo\n");
@@ -469,6 +503,11 @@ static void sun8i_ss_unregister_algs(struct sun8i_ss_dev *ss)
ss_algs[i].alg.skcipher.base.cra_name);
crypto_unregister_skcipher(&ss_algs[i].alg.skcipher);
break;
+ case CRYPTO_ALG_TYPE_RNG:
+ dev_info(ss->dev, "Unregister %d %s\n", i,
+ ss_algs[i].alg.rng.base.cra_name);
+ crypto_unregister_rng(&ss_algs[i].alg.rng);
+ break;
}
}
}
diff --git a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-prng.c b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-prng.c
new file mode 100644
index 000000000000..b5752692991e
--- /dev/null
+++ b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-prng.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * sun8i-ss-prng.c - hardware cryptographic offloader for
+ * Allwinner A80/A83T SoC
+ *
+ * Copyright (C) 2015-2020 Corentin Labbe <clabbe@baylibre.com>
+ *
+ * This file handle the PRNG found in the SS
+ *
+ * You could find a link for the datasheet in Documentation/arm/sunxi.rst
+ */
+#include "sun8i-ss.h"
+#include <linux/pm_runtime.h>
+#include <crypto/internal/rng.h>
+
+int sun8i_ss_prng_seed(struct crypto_rng *tfm, const u8 *seed,
+ unsigned int slen)
+{
+ struct sun8i_ss_rng_tfm_ctx *ctx = crypto_rng_ctx(tfm);
+
+ if (ctx->seed && ctx->slen != slen) {
+ memzero_explicit(ctx->seed, ctx->slen);
+ kfree(ctx->seed);
+ ctx->slen = 0;
+ ctx->seed = NULL;
+ }
+ if (!ctx->seed)
+ ctx->seed = kmalloc(slen, GFP_KERNEL | GFP_DMA);
+ if (!ctx->seed)
+ return -ENOMEM;
+
+ memcpy(ctx->seed, seed, slen);
+ ctx->slen = slen;
+
+ return 0;
+}
+
+int sun8i_ss_prng_init(struct crypto_tfm *tfm)
+{
+ struct sun8i_ss_rng_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
+
+ memset(ctx, 0, sizeof(struct sun8i_ss_rng_tfm_ctx));
+ return 0;
+}
+
+void sun8i_ss_prng_exit(struct crypto_tfm *tfm)
+{
+ struct sun8i_ss_rng_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
+
+ memzero_explicit(ctx->seed, ctx->slen);
+ kfree(ctx->seed);
+ ctx->seed = NULL;
+ ctx->slen = 0;
+}
+
+int sun8i_ss_prng_generate(struct crypto_rng *tfm, const u8 *src,
+ unsigned int slen, u8 *dst, unsigned int dlen)
+{
+ struct sun8i_ss_rng_tfm_ctx *ctx = crypto_rng_ctx(tfm);
+ struct rng_alg *alg = crypto_rng_alg(tfm);
+ struct sun8i_ss_alg_template *algt;
+ struct sun8i_ss_dev *ss;
+ dma_addr_t dma_iv, dma_dst;
+ unsigned int todo;
+ int err = 0;
+ int flow;
+ void *d;
+ u32 v;
+
+ algt = container_of(alg, struct sun8i_ss_alg_template, alg.rng);
+ ss = algt->ss;
+
+ if (ctx->slen == 0) {
+ dev_err(ss->dev, "The PRNG is not seeded\n");
+ return -EINVAL;
+ }
+
+ /* The SS does not give an updated seed, so we need to get a new one.
+ * So we will ask for an extra PRNG_SEED_SIZE data.
+ * We want dlen + seedsize rounded up to a multiple of PRNG_DATA_SIZE
+ */
+ todo = dlen + PRNG_SEED_SIZE + PRNG_DATA_SIZE;
+ todo -= todo % PRNG_DATA_SIZE;
+
+ d = kzalloc(todo, GFP_KERNEL | GFP_DMA);
+ if (!d)
+ return -ENOMEM;
+
+ flow = sun8i_ss_get_engine_number(ss);
+
+#ifdef CONFIG_CRYPTO_DEV_SUN8I_SS_DEBUG
+ algt->stat_req++;
+ algt->stat_bytes += todo;
+#endif
+
+ v = SS_ALG_PRNG | SS_PRNG_CONTINUE | SS_START;
+ if (flow)
+ v |= SS_FLOW1;
+ else
+ v |= SS_FLOW0;
+
+ dma_iv = dma_map_single(ss->dev, ctx->seed, ctx->slen, DMA_TO_DEVICE);
+ if (dma_mapping_error(ss->dev, dma_iv)) {
+ dev_err(ss->dev, "Cannot DMA MAP IV\n");
+ return -EFAULT;
+ }
+
+ dma_dst = dma_map_single(ss->dev, d, todo, DMA_FROM_DEVICE);
+ if (dma_mapping_error(ss->dev, dma_dst)) {
+ dev_err(ss->dev, "Cannot DMA MAP DST\n");
+ err = -EFAULT;
+ goto err_iv;
+ }
+
+ err = pm_runtime_get_sync(ss->dev);
+ if (err < 0)
+ goto err_pm;
+ err = 0;
+
+ mutex_lock(&ss->mlock);
+ writel(dma_iv, ss->base + SS_IV_ADR_REG);
+ /* the PRNG act badly (failing rngtest) without SS_KEY_ADR_REG set */
+ writel(dma_iv, ss->base + SS_KEY_ADR_REG);
+ writel(dma_dst, ss->base + SS_DST_ADR_REG);
+ writel(todo / 4, ss->base + SS_LEN_ADR_REG);
+
+ reinit_completion(&ss->flows[flow].complete);
+ ss->flows[flow].status = 0;
+ /* Be sure all data is written before enabling the task */
+ wmb();
+
+ writel(v, ss->base + SS_CTL_REG);
+
+ wait_for_completion_interruptible_timeout(&ss->flows[flow].complete,
+ msecs_to_jiffies(todo));
+ if (ss->flows[flow].status == 0) {
+ dev_err(ss->dev, "DMA timeout for PRNG (size=%u)\n", todo);
+ err = -EFAULT;
+ }
+ /* Since cipher and hash use the linux/cryptoengine and that we have
+ * a cryptoengine per flow, we are sure that they will issue only one
+ * request per flow.
+ * Since the cryptoengine wait for completion before submitting a new
+ * one, the mlock could be left just after the final writel.
+ * But cryptoengine cannot handle crypto_rng, so we need to be sure
+ * nothing will use our flow.
+ * The easiest way is to grab mlock until the hardware end our requests.
+ * We could have used a per flow lock, but this would increase
+ * complexity.
+ * The drawback is that no request could be handled for the other flow.
+ */
+ mutex_unlock(&ss->mlock);
+
+ pm_runtime_put(ss->dev);
+
+err_pm:
+ dma_unmap_single(ss->dev, dma_dst, todo, DMA_FROM_DEVICE);
+err_iv:
+ dma_unmap_single(ss->dev, dma_iv, ctx->slen, DMA_TO_DEVICE);
+
+ if (!err) {
+ memcpy(dst, d, dlen);
+ /* Update seed */
+ memcpy(ctx->seed, d + dlen, ctx->slen);
+ }
+ memzero_explicit(d, todo);
+ kfree(d);
+
+ return err;
+}
diff --git a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss.h b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss.h
index f3ffaea3a59f..adf2ee2395c1 100644
--- a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss.h
+++ b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss.h
@@ -8,6 +8,7 @@
#include <crypto/aes.h>
#include <crypto/des.h>
#include <crypto/engine.h>
+#include <crypto/rng.h>
#include <crypto/skcipher.h>
#include <linux/atomic.h>
#include <linux/debugfs.h>
@@ -21,6 +22,7 @@
#define SS_ALG_AES 0
#define SS_ALG_DES (1 << 2)
#define SS_ALG_3DES (2 << 2)
+#define SS_ALG_PRNG (4 << 2)

#define SS_CTL_REG 0x00
#define SS_INT_CTL_REG 0x04
@@ -52,6 +54,8 @@
#define SS_FLOW0 BIT(30)
#define SS_FLOW1 BIT(31)

+#define SS_PRNG_CONTINUE BIT(18)
+
#define MAX_SG 8

#define MAXFLOW 2
@@ -61,6 +65,9 @@
#define SS_DIE_ID_SHIFT 20
#define SS_DIE_ID_MASK 0x07

+#define PRNG_DATA_SIZE (160 / 8)
+#define PRNG_SEED_SIZE DIV_ROUND_UP(175, 8)
+
/*
* struct ss_clock - Describe clocks used by sun8i-ss
* @name: Name of clock needed by this variant
@@ -181,6 +188,16 @@ struct sun8i_cipher_tfm_ctx {
struct crypto_skcipher *fallback_tfm;
};

+/*
+ * struct sun8i_ss_prng_ctx - context for PRNG TFM
+ * @seed: The seed to use
+ * @slen: The size of the seed
+ */
+struct sun8i_ss_rng_tfm_ctx {
+ void *seed;
+ unsigned int slen;
+};
+
/*
* struct sun8i_ss_alg_template - crypto_alg template
* @type: the CRYPTO_ALG_TYPE for this template
@@ -191,6 +208,7 @@ struct sun8i_cipher_tfm_ctx {
* @alg: one of sub struct must be used
* @stat_req: number of request done on this template
* @stat_fb: number of request which has fallbacked
+ * @stat_bytes: total data size done by this template
*/
struct sun8i_ss_alg_template {
u32 type;
@@ -199,10 +217,12 @@ struct sun8i_ss_alg_template {
struct sun8i_ss_dev *ss;
union {
struct skcipher_alg skcipher;
+ struct rng_alg rng;
} alg;
#ifdef CONFIG_CRYPTO_DEV_SUN8I_SS_DEBUG
unsigned long stat_req;
unsigned long stat_fb;
+ unsigned long stat_bytes;
#endif
};

@@ -220,3 +240,8 @@ int sun8i_ss_skencrypt(struct skcipher_request *areq);
int sun8i_ss_get_engine_number(struct sun8i_ss_dev *ss);

int sun8i_ss_run_task(struct sun8i_ss_dev *ss, struct sun8i_cipher_req_ctx *rctx, const char *name);
+int sun8i_ss_prng_generate(struct crypto_rng *tfm, const u8 *src,
+ unsigned int slen, u8 *dst, unsigned int dlen);
+int sun8i_ss_prng_seed(struct crypto_rng *tfm, const u8 *seed, unsigned int slen);
+int sun8i_ss_prng_init(struct crypto_tfm *tfm);
+void sun8i_ss_prng_exit(struct crypto_tfm *tfm);
--
2.26.2