124 lines
3.4 KiB
Diff
124 lines
3.4 KiB
Diff
===============================================================================
|
|
|
|
This patch makes MAC addresses of network interfaces predictable. In
|
|
particular, it adds a small routine that computes MAC addresses of based on
|
|
a SHA1 hash of the virtual machine name and interface ID.
|
|
|
|
TECHNICAL INFORMATION:
|
|
|
|
Applies to vanilla kernel 3.9.4.
|
|
|
|
===============================================================================
|
|
--- a/arch/um/Kconfig.net
|
|
+++ b/arch/um/Kconfig.net
|
|
@@ -21,6 +21,19 @@ config UML_NET
|
|
enable at least one of the following transport options to actually
|
|
make use of UML networking.
|
|
|
|
+config UML_NET_RANDOM_MAC
|
|
+ bool "Use random MAC addresses for network interfaces"
|
|
+ default n
|
|
+ depends on UML_NET
|
|
+ help
|
|
+ Virtual network devices inside a User-Mode Linux instance must be
|
|
+ assigned a MAC (Ethernet) address. If none is specified on the UML
|
|
+ command line, one must be automatically computed. If this option is
|
|
+ enabled, a randomly generated address is used. Otherwise, if this
|
|
+ option is disabled, the address is generated from a SHA1 hash of
|
|
+ the umid of the UML instance and the interface name. The latter choice
|
|
+ is useful to make MAC addresses predictable.
|
|
+
|
|
config UML_NET_ETHERTAP
|
|
bool "Ethertap transport"
|
|
depends on UML_NET
|
|
--- a/arch/um/drivers/net_kern.c
|
|
+++ b/arch/um/drivers/net_kern.c
|
|
@@ -25,6 +25,13 @@
|
|
#include <net_kern.h>
|
|
#include <net_user.h>
|
|
|
|
+#include <crypto/sha.h>
|
|
+#include <linux/string.h>
|
|
+#include <linux/crypto.h>
|
|
+#include <linux/err.h>
|
|
+#include <linux/scatterlist.h>
|
|
+#include "os.h"
|
|
+
|
|
#define DRIVER_NAME "uml-netdev"
|
|
|
|
static DEFINE_SPINLOCK(opened_lock);
|
|
@@ -295,11 +302,47 @@ static void uml_net_user_timer_expire(un
|
|
#endif
|
|
}
|
|
|
|
+#ifndef CONFIG_UML_NET_RANDOM_MAC
|
|
+
|
|
+/* Compute a SHA1 hash of the UML instance's id and
|
|
+ * * an interface name. */
|
|
+static int compute_hash(const char *umid, const char *ifname, char *hash) {
|
|
+ char vmif[1024];
|
|
+ struct scatterlist sg;
|
|
+ struct crypto_hash *tfm;
|
|
+ struct hash_desc desc;
|
|
+
|
|
+ strcpy (vmif, umid);
|
|
+ strcat (vmif, ifname);
|
|
+
|
|
+ tfm = crypto_alloc_hash("sha1", 0, CRYPTO_ALG_ASYNC);
|
|
+ if (IS_ERR(tfm))
|
|
+ return 1;
|
|
+
|
|
+ desc.tfm = tfm;
|
|
+ desc.flags = 0;
|
|
+
|
|
+ sg_init_table(&sg, 1);
|
|
+ sg_set_buf(&sg, vmif, strlen(vmif));
|
|
+
|
|
+ if (crypto_hash_digest(&desc, &sg, strlen(vmif), hash)) {
|
|
+ crypto_free_hash(tfm);
|
|
+ return 1;
|
|
+ }
|
|
+
|
|
+ crypto_free_hash(tfm);
|
|
+
|
|
+ return 0;
|
|
+}
|
|
+
|
|
+#endif
|
|
+
|
|
static void setup_etheraddr(struct net_device *dev, char *str)
|
|
{
|
|
unsigned char *addr = dev->dev_addr;
|
|
char *end;
|
|
int i;
|
|
+ u8 hash[SHA1_DIGEST_SIZE];
|
|
|
|
if (str == NULL)
|
|
goto random;
|
|
@@ -340,9 +383,26 @@ static void setup_etheraddr(struct net_d
|
|
return;
|
|
|
|
random:
|
|
+#ifdef CONFIG_UML_NET_RANDOM_MAC
|
|
printk(KERN_INFO
|
|
"Choosing a random ethernet address for device %s\n", dev->name);
|
|
eth_hw_addr_random(dev);
|
|
+#else
|
|
+ printk(KERN_INFO
|
|
+ "Computing a digest to use as ethernet address for device %s\n", dev->name);
|
|
+ if (compute_hash(get_umid(), dev->name, hash)) {
|
|
+ printk(KERN_WARNING
|
|
+ "Could not compute digest to use as ethernet address for device %s. "
|
|
+ "Using random address instead.\n", dev->name);
|
|
+ random_ether_addr(addr);
|
|
+ }
|
|
+ else {
|
|
+ for (i=0; i < 6; i++)
|
|
+ addr[i] = (hash[i] + hash[i+6]) % 0x100;
|
|
+ }
|
|
+ addr [0] &= 0xfe; /* clear multicast bit */
|
|
+ addr [0] |= 0x02; /* set local assignment bit (IEEE802) */
|
|
+#endif
|
|
}
|
|
|
|
static DEFINE_SPINLOCK(devices_lock);
|