diff options
Diffstat (limited to 'target/linux/uml/patches-4.1/102-pseudo-random-mac.patch')
| -rw-r--r-- | target/linux/uml/patches-4.1/102-pseudo-random-mac.patch | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/target/linux/uml/patches-4.1/102-pseudo-random-mac.patch b/target/linux/uml/patches-4.1/102-pseudo-random-mac.patch new file mode 100644 index 0000000..fc54f60 --- /dev/null +++ b/target/linux/uml/patches-4.1/102-pseudo-random-mac.patch @@ -0,0 +1,124 @@ +=============================================================================== + +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); |