uml: Add 4.9 kernel patches

[openwrt/openwrt.git] / target / linux / uml / patches-4.9 / 102-pseudo-random-mac.patch

diff --git a/target/linux/uml/patches-4.9/102-pseudo-random-mac.patch b/target/linux/uml/patches-4.9/102-pseudo-random-mac.patch
new file mode 100644 (file)
index 0000000..a31d75f
--- /dev/null
+++ b/target/linux/uml/patches-4.9/102-pseudo-random-mac.patch
@@ -0,0 +1,131 @@
+===============================================================================
+
+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 +25,14 @@
+ #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);
+@@ -295,11 +303,53 @@ 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)
++{
++      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
++
+ 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 +390,26 @@ 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) < 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);