ASR_BASE
Change-Id: Icf3719cc0afe3eeb3edc7fa80a2eb5199ca9dda1
diff --git a/target/linux/uml/patches-5.4/102-pseudo-random-mac.patch b/target/linux/uml/patches-5.4/102-pseudo-random-mac.patch
new file mode 100644
index 0000000..1969636
--- /dev/null
+++ b/target/linux/uml/patches-5.4/102-pseudo-random-mac.patch
@@ -0,0 +1,130 @@
+===============================================================================
+
+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/drivers/Kconfig
++++ b/arch/um/drivers/Kconfig
+@@ -146,6 +146,20 @@ config UML_NET
+ enable at least one of the following transport options to actually
+ make use of UML networking.
+
++config UML_NET_DETERMINISTIC_MAC
++ bool "Use deterministic MAC addresses for network interfaces"
++ default y
++ depends on UML_NET
++ select CRYPTO_SHA1
++ 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 +25,14 @@
+ #include <net_kern.h>
+ #include <net_user.h>
+
++#include <crypto/sha.h>
++#include <crypto/hash.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);
+@@ -286,9 +294,51 @@ static void uml_net_user_timer_expire(st
+ #endif
+ }
+
++#ifdef CONFIG_UML_NET_DETERMINISTIC_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)
++{
++ struct ahash_request *desc;
++ struct crypto_ahash *tfm;
++ struct scatterlist sg;
++ char vmif[1024];
++ int ret;
++
++ strcpy (vmif, umid);
++ strcat (vmif, ifname);
++
++ tfm = crypto_alloc_ahash("sha1", 0, CRYPTO_ALG_ASYNC);
++ if (IS_ERR(tfm))
++ return -ENOMEM;
++
++ desc = ahash_request_alloc(tfm, GFP_KERNEL);
++ if (!desc) {
++ ret = -ENOMEM;
++ goto out;
++ }
++
++ crypto_ahash_clear_flags(tfm, ~0);
++
++ sg_init_table(&sg, 1);
++ sg_set_buf(&sg, vmif, strlen(vmif));
++
++ ahash_request_set_crypt(desc, &sg, hash, strlen(vmif));
++
++ ret = crypto_ahash_digest(desc);
++out:
++ crypto_free_ahash(tfm);
++
++ return ret;
++}
++
++#endif
++
+ void uml_net_setup_etheraddr(struct net_device *dev, char *str)
+ {
+ unsigned char *addr = dev->dev_addr;
++ u8 hash[SHA1_DIGEST_SIZE];
+ char *end;
+ int i;
+
+@@ -331,9 +381,26 @@ void uml_net_setup_etheraddr(struct net_
+ return;
+
+ random:
++#ifndef CONFIG_UML_NET_DETERMINISTIC_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) < 0) {
++ 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);