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 + 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
