Initial commit
This commit is contained in:
		
							
								
								
									
										130
									
								
								target/linux/uml/patches-5.4/102-pseudo-random-mac.patch
									
									
									
									
									
										Normal file
									
								
							
							
						
						
									
										130
									
								
								target/linux/uml/patches-5.4/102-pseudo-random-mac.patch
									
									
									
									
									
										Normal file
									
								
							| @@ -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); | ||||
		Reference in New Issue
	
	Block a user
	 domenico
					domenico