[PATCH 08/10] lib: random: add hwrng_get_crypto_bytes

[Ahmad Fatoum]

We already have get_crypto_bytes to get access to hardware generated
randomness. barebox as EFI loader would provide a handle for each HWRNG,
so add a hwrng_get_crypto_bytes function that can be used to implement
the load-side protocol.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 include/linux/hw_random.h |  6 +++++-
 include/stdlib.h          |  2 ++
 lib/random.c              | 25 ++++++++++++-------------
 3 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/include/linux/hw_random.h b/include/linux/hw_random.h
index 116afd9721e5..e541abfa176e 100644
--- a/include/linux/hw_random.h
+++ b/include/linux/hw_random.h
@@ -36,12 +36,16 @@ struct hwrng {
 
 /* Register a new Hardware Random Number Generator driver. */
 int hwrng_register(struct device_d *dev, struct hwrng *rng);
-int hwrng_get_data(struct hwrng *rng, void *buffer, size_t size, int wait);
 
 #ifdef CONFIG_HWRNG
 struct hwrng *hwrng_get_first(void);
+int hwrng_get_data(struct hwrng *rng, void *buffer, size_t size, int wait);
 #else
 static inline struct hwrng *hwrng_get_first(void) { return ERR_PTR(-ENODEV); };
+static inline int hwrng_get_data(struct hwrng *rng, void *buffer, size_t size, int wait)
+{
+	return -ENODEV;
+}
 #endif
 
 void hwrng_unregister(struct hwrng *rng);
diff --git a/include/stdlib.h b/include/stdlib.h
index 8eb419e111f0..0305970557df 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -15,6 +15,8 @@ void srand(unsigned int seed);
 /* fill a buffer with pseudo-random data */
 void get_random_bytes(void *buf, int len);
 int get_crypto_bytes(void *buf, int len);
+struct hwrng;
+int hwrng_get_crypto_bytes(struct hwrng *rng, void *buf, int len);
 
 static inline u32 random32(void)
 {
diff --git a/lib/random.c b/lib/random.c
index fb3580f9c086..c6532df55249 100644
--- a/lib/random.c
+++ b/lib/random.c
@@ -34,17 +34,8 @@ void get_random_bytes(void *_buf, int len)
 		*buf++ = rand() % 256;
 }
 
-/**
- * get_crypto_bytes - get random numbers suitable for cryptographic needs.
- */
-static int _get_crypto_bytes(void *buf, int len)
+int hwrng_get_crypto_bytes(struct hwrng *rng, void *buf, int len)
 {
-	struct hwrng *rng;
-
-	rng = hwrng_get_first();
-	if (IS_ERR(rng))
-		return PTR_ERR(rng);
-
 	while (len) {
 		int bytes = hwrng_get_data(rng, buf, len, true);
 		if (!bytes)
@@ -60,13 +51,21 @@ static int _get_crypto_bytes(void *buf, int len)
 	return 0;
 }
 
+/**
+ * get_crypto_bytes - get random numbers suitable for cryptographic needs.
+ */
 int get_crypto_bytes(void *buf, int len)
 {
+	struct hwrng *rng;
 	int err;
 
-	err = _get_crypto_bytes(buf, len);
-	if (!err)
-		return 0;
+	rng = hwrng_get_first();
+	err = PTR_ERR_OR_ZERO(rng);
+	if (!err) {
+		err = hwrng_get_crypto_bytes(rng, buf, len);
+		if (!err)
+			return 0;
+	}
 
 	if (!IS_ENABLED(CONFIG_ALLOW_PRNG_FALLBACK)) {
 		pr_err("error: no HWRNG available!\n");
-- 
2.30.2