Hi Ahmad,
On Mon, Sep 11, 2023 at 05:59:27PM +0200, Ahmad Fatoum wrote:
> From: Ahmad Fatoum <[email protected]>
>
> Especially during development, devices often lack a MAC address. While a
> MAC address can be easily added to the environment:
>
> nv dev.eth0.ethaddr="aa:bb:cc:dd:ee:ff"
>
> It's easily lost when flashing complete new images, e.g. from CI.
> Make the development experience neater by deriving a stable MAC address
> if possible.
>
> Signed-off-by: Ahmad Fatoum <[email protected]>
> ---
> include/net.h | 2 ++
> net/Kconfig | 17 +++++++++++++++++
> net/eth.c | 11 ++++++++++-
> net/net.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++--
> 4 files changed, 76 insertions(+), 3 deletions(-)
>
> diff --git a/include/net.h b/include/net.h
> index a0ef8bee0404..de43c29f74ac 100644
> --- a/include/net.h
> +++ b/include/net.h
> @@ -418,6 +418,8 @@ static inline int is_broadcast_ether_addr(const u8 *addr)
> #define ETH_ALEN 6 /* Octets in an Ethernet address */
> #define ETH_HLEN 14 /* Total octets in header.*/
>
> +int generate_ether_addr(u8 *addr, int ethid);
> +
> /**
> * random_ether_addr - Generate software assigned random Ethernet address
> * @addr: Pointer to a six-byte array containing the Ethernet address
> diff --git a/net/Kconfig b/net/Kconfig
> index 59f14c23cba2..04fcdcbe5bd5 100644
> --- a/net/Kconfig
> +++ b/net/Kconfig
> @@ -6,6 +6,23 @@ menuconfig NET
>
> if NET
>
> +config NET_ETHADDR_FROM_MACHINE_ID
> + bool
> + prompt "generate stable Ethernet address"
> + depends on MACHINE_ID && HAVE_DIGEST_SHA256 && HAVE_DIGEST_HMAC
> + help
> + By default, barebox will generate random Ethernet addresses for
> + interfaces that had no explicit Ethernet address set via
> + either board code or NVMEM properties in device tree.
> +
> + Say y here, to randomize Ethernet addresses only if no machine ID
> + is available. Should barebox have a machine ID, it will be used
> + alonside the hostname to generate MAC addresses that are unlikely
s/alonside/alongside/
> + to change between subsequent runs of barebox.
> +
> + This is not recommended for use in production as it may leak
> + information about the machine ID.
> +
> config NET_NFS
> bool
> prompt "nfs support"
> diff --git a/net/eth.c b/net/eth.c
> index ccac5e2a6488..e74c00e74a9a 100644
> --- a/net/eth.c
> +++ b/net/eth.c
> @@ -10,6 +10,7 @@
> #include <dhcp.h>
> #include <net.h>
> #include <dma.h>
> +#include <machine_id.h>
> #include <of.h>
> #include <of_net.h>
> #include <linux/phy.h>
> @@ -558,6 +559,7 @@ static int of_populate_ethaddr(void)
> {
> char str[sizeof("xx:xx:xx:xx:xx:xx")];
> struct eth_device *edev;
> + bool generated = false;
> int ret;
>
> list_for_each_entry(edev, &netdev_list, list) {
> @@ -566,11 +568,18 @@ static int of_populate_ethaddr(void)
>
> ret = of_get_mac_addr_nvmem(edev->parent->of_node,
> edev->ethaddr);
> + if (ret && IS_ENABLED(CONFIG_NET_ETHADDR_FROM_MACHINE_ID)) {
> + ret = generate_ether_addr(edev->ethaddr, edev->dev.id);
> + generated = true;
> + }
> if (ret)
> continue;
>
> ethaddr_to_string(edev->ethaddr, str);
> - dev_info(&edev->dev, "Got preset MAC address from device tree:
> %s\n", str);
> + if (generated)
> + dev_notice(&edev->dev, "Generated MAC address from
> unique id: %s\n", str);
> + else
> + dev_info(&edev->dev, "Got preset MAC address from
> NVMEM: %s\n", str);
> eth_set_ethaddr(edev, edev->ethaddr);
> }
>
> diff --git a/net/net.c b/net/net.c
> index bf2117ff7ec2..e38179491d7a 100644
> --- a/net/net.c
> +++ b/net/net.c
> @@ -25,6 +25,7 @@
> #include <init.h>
> #include <globalvar.h>
> #include <magicvar.h>
> +#include <machine_id.h>
> #include <linux/ctype.h>
> #include <linux/err.h>
>
> @@ -365,6 +366,43 @@ IPaddr_t net_get_gateway(void)
>
> static LIST_HEAD(connection_list);
>
> +/**
> + * generate_ether_addr - Generates stable software assigned Ethernet address
> + * @addr: Pointer to a six-byte array to contain the Ethernet address
> + * @ethid: index of the Ethernet interface
> + *
> + * Derives an Ethernet address (MAC) from the machine ID, that's stable
> + * per board that is not multicast and has the local assigned bit set.
> + *
> + * Return 0 if an address could be generated or a negative error code
> otherwise.
> + */
> +int generate_ether_addr(u8 *ethaddr, int ethid)
> +{
> + const char *hostname;
> + uuid_t id;
> + int ret;
> +
> + if (!IS_ENABLED(CONFIG_NET_ETHADDR_FROM_MACHINE_ID))
> + return -ENOSYS;
> +
> + hostname = barebox_get_hostname();
> + if (!hostname)
> + return -EINVAL;
> +
> + ret = machine_id_get_app_specific(&id,
> ARRAY_AND_SIZE("barebox-macaddr:"),
> + hostname, strlen(hostname), NULL);
> + if (ret)
> + return ret;
> +
> + memcpy(ethaddr, &id.b, ETH_ALEN);
> + eth_addr_add(ethaddr, ethid);
> +
> + ethaddr[0] &= 0xfe; /* clear multicast bit */
> + ethaddr[0] |= 0x02; /* set local assignment bit (IEEE802) */
> +
> + return 0;
> +}
> +
> static struct net_connection *net_new(struct eth_device *edev, IPaddr_t dest,
> rx_handler_f *handler, void *ctx)
> {
> @@ -381,9 +419,16 @@ static struct net_connection *net_new(struct eth_device
> *edev, IPaddr_t dest,
>
> if (!is_valid_ether_addr(edev->ethaddr)) {
> char str[sizeof("xx:xx:xx:xx:xx:xx")];
> - random_ether_addr(edev->ethaddr);
> +
> + ret = generate_ether_addr(edev->ethaddr, edev->dev.id);
> + if (ret)
> + random_ether_addr(edev->ethaddr);
> +
> ethaddr_to_string(edev->ethaddr, str);
> - dev_warn(&edev->dev, "No MAC address set. Using random address
> %s\n", str);
> +
> + dev_warn(&edev->dev, "No MAC address set. Using %s %s\n",
> + ret == 1 ? "address computed from unique ID" : "random
> address",
> + str);
> eth_set_ethaddr(edev, edev->ethaddr);
> }
>
> --
> 2.39.2
>
>
Regards
Thorsten
