Initial commit

target/linux/uml/patches-6.6/102-pseudo-random-mac.patch

@@ -0,0 +1,151 @@
+===============================================================================
+
+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
+@@ -143,6 +143,20 @@ 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 (obsolete)"
+ 	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/sha1.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);
+@@ -274,9 +282,55 @@ static const struct ethtool_ops uml_net_
+ 	.get_ts_info	= ethtool_op_get_ts_info,
+ };
+ 
++#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 = NULL;
++	struct crypto_ahash *tfm = NULL;
++	struct scatterlist sg;
++	char *vmif = NULL;
++	int ret = -ENOMEM;
++
++	vmif = kmalloc(1024, GFP_KERNEL);
++	if (!vmif)
++		goto out;
++
++	strcpy (vmif, umid);
++	strcat (vmif, ifname);
++
++	tfm = crypto_alloc_ahash("sha1", 0, CRYPTO_ALG_ASYNC);
++	if (IS_ERR(tfm))
++		goto out;
++
++	desc = ahash_request_alloc(tfm, GFP_KERNEL);
++	if (!desc)
++		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);
++	ahash_request_free(desc);
++	kfree(vmif);
++
++	return ret;
++}
++
++#endif
++
+ void uml_net_setup_etheraddr(struct net_device *dev, char *str)
+ {
+ 	u8 addr[ETH_ALEN];
++	u8 hash[SHA1_DIGEST_SIZE];
+ 	char *end;
+ 	int i;
+ 
+@@ -320,9 +374,26 @@ 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);
++		eth_random_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);
+--- a/kernel/umh.c
++++ b/kernel/umh.c
+@@ -354,12 +354,12 @@ static void helper_unlock(void)
+ }
+ 
+ int call_usermodehelper_stdoutpipe(struct subprocess_info *sub_info,
+-					struct file **filp)
++				   struct file **filp)
+ {
+ 	struct file *f[2];
+ 
+ 	if (create_pipe_files(f, 0) < 0)
+-		 return PTR_ERR(f);
++		return PTR_ERR(f);
+ 
+ 	sub_info->stdout = f[1];
+ 	*filp = f[0];