From: Michael Tremer <michael.tremer@ipfire.org>
Date: Sat, 11 Feb 2023 12:01:42 +0000 (+0000)
Subject: networkd: Generate a random Ethernet address for ports
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9a93da54510ec2b49e0890d2b420a097316eaace;p=network.git

networkd: Generate a random Ethernet address for ports

This happens when either no address was set, or it cannot be parsed.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/networkd/address.h b/src/networkd/address.h
index 1d9fbfc9..f875b261 100644
--- a/src/networkd/address.h
+++ b/src/networkd/address.h
@@ -23,6 +23,9 @@
 
 #include <netinet/ether.h>
 #include <string.h>
+#include <sys/random.h>
+
+#include "logging.h"
 
 typedef struct ether_addr nw_address_t;
 
@@ -44,4 +47,26 @@ static inline char* nw_address_to_string(const nw_address_t* addr) {
 	return strdup(buffer);
 }
 
+static inline int nw_address_generate(nw_address_t* addr) {
+	ssize_t bytes = getrandom(addr, sizeof(*addr), 0);
+	if (bytes < 0) {
+		ERROR("getrandom() failed: %m\n");
+		return 1;
+	}
+
+	// Check if we filled the entire buffer
+	if (bytes < (ssize_t)sizeof(*addr)) {
+		ERROR("Could not gather enough randomness\n");
+		return 1;
+	}
+
+	// Clear the multicast bit
+	addr->ether_addr_octet[0] &= 0xfe;
+
+	// Set the software-generated bit
+	addr->ether_addr_octet[1] |= 0x02;
+
+	return 0;
+}
+
 #endif /* NETWORKD_ADDRESS_H */
diff --git a/src/networkd/port.c b/src/networkd/port.c
index aff79a53..4c325924 100644
--- a/src/networkd/port.c
+++ b/src/networkd/port.c
@@ -75,18 +75,28 @@ static int nw_port_setup_address(struct nw_port* port) {
 	const char* s = nw_config_get(port->config, "ADDRESS");
 	if (!s) {
 		ERROR("Port %s: Address isn't set\n", port->name);
-		return 1;
+		goto ERROR;
 	}
 
 	// Parse the address
 	r = nw_address_from_string(&port->address, s);
 	if (r) {
 		ERROR("Port %s: Could not parse address: %m\n", port->name);
-		return r;
+		goto ERROR;
 	}
 
 	// XXX Do we need to check for multicast here?
 
+	return 0;
+
+ERROR:
+	// Generate a random Ethernet address
+	r = nw_address_generate(&port->address);
+	if (r) {
+		ERROR("Could not generate a random Ethernet address: %m\n");
+		return r;
+	}
+
 	return 0;
 }