From: Ahmad Fatoum <ahmad@xxxxxx>
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 <a.fatoum@xxxxxxxxxxxxxx>
---
include/net.h | 2 ++
net/Kconfig | 17 +++++++++++++++++
net/eth.c | 15 ++++++++++++---
net/net.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++--
4 files changed, 78 insertions(+), 5 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..07e623670e22 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
+ alongside 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..d1474ec57df3 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>
@@ -554,10 +555,11 @@ void eth_open_all(void)
}
}
-static int of_populate_ethaddr(void)
+static int 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) {
@@ -566,14 +568,21 @@ static int of_populate_ethaddr(void)
ret = of_get_mac_addr_nvmem(edev->parent->of_node,
edev->ethaddr);
+ if (IS_ENABLED(CONFIG_NET_ETHADDR_FROM_MACHINE_ID) && ret) {
+ 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);
}
return 0;
}
-postenvironment_initcall(of_populate_ethaddr);
+postenvironment_initcall(populate_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);
}
--
2.42.0
