[PATCH 2/2] net: Use NDRNG device in srand_mac()

[matthias.bgg at kernel.org <matthias.bgg@kernel.org>]

From: Matthias Brugger <mbrugger@suse.com>

When calling srand_mac we use a weak seed dependent on the
mac address. If present, use a RNG device instead to incerase entropy.

Signed-off-by: Matthias Brugger <mbrugger@suse.com>

---

 net/net_rand.h | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/net/net_rand.h b/net/net_rand.h
index 4bf9bd817e..600c3d825e 100644
--- a/net/net_rand.h
+++ b/net/net_rand.h
@@ -10,6 +10,7 @@
 #define __NET_RAND_H__
 
 #include <common.h>
+#include <rng.h>
 
 /*
  * Return a seed for the PRNG derived from the eth0 MAC address.
@@ -37,7 +38,22 @@ static inline unsigned int seed_mac(void)
  */
 static inline void srand_mac(void)
 {
-	srand(seed_mac());
+#if defined(CONFIG_DM_RNG)
+	int ret;
+	struct udevice *devp;
+	u32 randv = 0;
+
+	ret = uclass_get_device(UCLASS_RNG, 0, &devp);
+	if (ret) {
+		ret = dm_rng_read(dev, randv, sizeof(randv));
+		if (ret < 0)
+			randv = 0;
+	}
+	if (randv)
+		srand(randv);
+	else
+#endif
+		srand(seed_mac());
 }
 
 #endif /* __NET_RAND_H__ */
-- 
2.29.2