diff mbox series

rockchip: use stable MAC-address for NanoPi R2S

Message ID 20210116134638.10418-1-mail@david-bauer.net
State Accepted
Delegated to: David Bauer
Headers show
Series rockchip: use stable MAC-address for NanoPi R2S | expand

Commit Message

David Bauer Jan. 16, 2021, 1:46 p.m. UTC
The NanoPi R2S does not have a board specific MAC address written inside
e.g. an EEPROM, hence why it is randomly generated on first boot.

The issue with that however is the lack of a driver for the PRNG.
It often results to the same MAC address used on multiple boards by
default, as urngd is not active at this early stage resulting in low
available entropy.

There is however a semi-unique identifier available to us, which is the
CID of the used SD card. It is unique to each SD card, hence we can use
it to generate the MAC address used for LAN and WAN.

Signed-off-by: David Bauer <mail@david-bauer.net>
---
 .../rockchip/armv8/base-files/etc/board.d/02_network     | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

Comments

Adrian Schmutzler Jan. 17, 2021, 12:14 a.m. UTC | #1
> +	local mac_base=$(macaddr_canonicalize "$(echo "${sd_hash}" | dd
> bs=1 count=12 2>/dev/null)")

bs=12 count=1 ?

Best

Adrian
Karl Palsson Jan. 17, 2021, 10:25 a.m. UTC | #2
"Adrian Schmutzler" <mail@adrianschmutzler.de> wrote:
> > +	local mac_base=$(macaddr_canonicalize "$(echo "${sd_hash}" | dd
> > bs=1 count=12 2>/dev/null)")
> 
> bs=12 count=1 ?


Why? unless you're passing other flags to try and magically avoid
the block layer, you're only operating on a 1k block read out
anyway. This sort of suggestion is pointless noise that just
makes things harder to read.

Sincerely,
Karl Palsson
diff mbox series

Patch

diff --git a/target/linux/rockchip/armv8/base-files/etc/board.d/02_network b/target/linux/rockchip/armv8/base-files/etc/board.d/02_network
index e129fd6a67..48133c81a1 100755
--- a/target/linux/rockchip/armv8/base-files/etc/board.d/02_network
+++ b/target/linux/rockchip/armv8/base-files/etc/board.d/02_network
@@ -17,6 +17,13 @@  rockchip_setup_interfaces()
 	esac
 }
 
+nanopi_r2s_generate_mac()
+{
+	local sd_hash=$(sha256sum /sys/devices/platform/ff500000.dwmmc/mmc_host/mmc0/mmc0:*/cid)
+	local mac_base=$(macaddr_canonicalize "$(echo "${sd_hash}" | dd bs=1 count=12 2>/dev/null)")
+	echo "$(macaddr_unsetbit_mc "$(macaddr_setbit_la "${mac_base}")")"
+}
+
 rockchip_setup_macs()
 {
 	local board="$1"
@@ -26,7 +33,7 @@  rockchip_setup_macs()
 
 	case "$board" in
 	friendlyarm,nanopi-r2s)
-		wan_mac=$(macaddr_random)
+		wan_mac=$(nanopi_r2s_generate_mac)
 		lan_mac=$(macaddr_add "$wan_mac" +1)
 		;;
 	esac