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u-boot/net/net_rand.h
Matthias Brugger ea707dc0aa net: Use NDRNG device in srand_mac()
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>
Reviewed-by: Torsten Duwe <duwe@suse.de>
2021-01-19 09:15:02 -05:00

60 lines
1.1 KiB
C

/*
* Copied from LiMon - BOOTP.
*
* Copyright 1994, 1995, 2000 Neil Russell.
* (See License)
* Copyright 2000 Paolo Scaffardi
*/
#ifndef __NET_RAND_H__
#define __NET_RAND_H__
#include <common.h>
#include <dm/uclass.h>
#include <rng.h>
/*
* Return a seed for the PRNG derived from the eth0 MAC address.
*/
static inline unsigned int seed_mac(void)
{
unsigned char enetaddr[ARP_HLEN];
unsigned int seed;
/* get our mac */
memcpy(enetaddr, eth_get_ethaddr(), ARP_HLEN);
seed = enetaddr[5];
seed ^= enetaddr[4] << 8;
seed ^= enetaddr[3] << 16;
seed ^= enetaddr[2] << 24;
seed ^= enetaddr[1];
seed ^= enetaddr[0] << 8;
return seed;
}
/*
* Seed the random number generator using the eth0 MAC address.
*/
static inline void srand_mac(void)
{
int ret;
struct udevice *devp;
u32 randv = 0;
if (IS_ENABLED(CONFIG_DM_RNG)) {
ret = uclass_get_device(UCLASS_RNG, 0, &devp);
if (ret) {
ret = dm_rng_read(devp, &randv, sizeof(randv));
if (ret < 0)
randv = 0;
}
}
if (randv)
srand(randv);
else
srand(seed_mac());
}
#endif /* __NET_RAND_H__ */