net: tun/tap: fixed hw address handling

From: Brian Braunstein <[email protected]>

Fixed tun/tap driver's handling of hw addresses. The hw address is stored in both the net_device.dev_addr and tun.dev_addr fields. These fields were not kept synchronized, and in fact weren't even initialized to the same value. Now during both init and when performing SIOCSIFHWADDR on the tun device these values are both updated. However, if SIOCSIFHWADDR is performed on the net device directly (for instance, setting the hw address using ifconfig), the tun device does not get updated. Perhaps the tun.dev_addr field should be removed completely at some point, as it is redundant and net_device.dev_addr can be used anywhere it is used.

---

Kernel Version: 2.6.20.4

@@ -18,6 +18,10 @@

/*
* Changes:
*
+ * Brian Braunstein <[email protected]> 2007/03/23
+ * Fixed hw address handling. Now net_device.dev_addr is kept consistent
+ * with tun.dev_addr when the address is set by this module.
+ *
* Mike Kershaw <[email protected]> 2005/08/14
* Add TUNSETLINK ioctl to set the link encapsulation
*
@@ -196,7 +200,10 @@ static void tun_net_init(struct net_devi

		dev->set_multicast_list = tun_net_mclist;

		ether_setup(dev);

- random_ether_addr(dev->dev_addr);
+
+ /* random address already created for us by tun_set_iff, use it */
+ memcpy(dev->dev_addr, tun->dev_addr, min(sizeof(tun->dev_addr), sizeof(dev->dev_addr)) );
+

		dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
		break;
	}
@@ -636,6 +643,7 @@ static int tun_chr_ioctl(struct inode *i
		return 0;

	case SIOCGIFHWADDR:
+		/* Note: the actual net device's address may be different */
		memcpy(ifr.ifr_hwaddr.sa_data, tun->dev_addr,
				min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
		if (copy_to_user( argp, &ifr, sizeof ifr))
@@ -643,16 +651,24 @@ static int tun_chr_ioctl(struct inode *i
		return 0;

	case SIOCSIFHWADDR:

- /** Set the character device's hardware address. This is used when
- * filtering packets being sent from the network device to the character
- * device. */
- memcpy(tun->dev_addr, ifr.ifr_hwaddr.sa_data,
- min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
- DBG(KERN_DEBUG "%s: set hardware address: %x:%x:%x:%x:%x:%x\n",
- tun->dev->name,
- tun->dev_addr[0], tun->dev_addr[1], tun->dev_addr[2],
- tun->dev_addr[3], tun->dev_addr[4], tun->dev_addr[5]);
- return 0;
+ {
+ /* try to set the actual net device's hw address */
+ int ret = dev_set_mac_address(tun->dev, &ifr.ifr_hwaddr);
+
+ if (ret == 0) {
+ /** Set the character device's hardware address. This is used when
+ * filtering packets being sent from the network device to the character
+ * device. */
+ memcpy(tun->dev_addr, ifr.ifr_hwaddr.sa_data,
+ min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
+ DBG(KERN_DEBUG "%s: set hardware address: %x:%x:%x:%x:%x:%x\n",
+ tun->dev->name,
+ tun->dev_addr[0], tun->dev_addr[1], tun->dev_addr[2],
+ tun->dev_addr[3], tun->dev_addr[4], tun->dev_addr[5]);
+ }
+
+ return ret;
+ }

	case SIOCADDMULTI:
		/** Add the specified group to the character device's multicast filter

No need for this line. This line is used when you _forward_ another patch from others. Signed-off-by is enough

It's always better to generate the patch against the latest -rc kernel.

Your mailer still wrap the long lines mistakenly as it did in the first version of the patch.

Regards,

Ahmed S. Darwish
http://darwish.07.googlepages.com

It seems a bug in my mutt mail reader (not a feature, it displays other mails long lines without wrapping), sorry.

Ahmed S. Darwish
http://darwish.07.googlepages.com

Patch is hopelessly corrupted:
missing leading space in context lines
<tab> converted to four spaces

Okay, the attached patch applies. Can someone comment on whether it makes sense? (pasted inline for comments)

From: Brian Braunstein <[email protected]>

Fixed tun/tap driver's handling of hw addresses. The hw address is stored in both the net_device.dev_addr and tun.dev_addr fields. These fields were not kept synchronized, and in fact weren't even initialized to the same value. Now during both init and when performing SIOCSIFHWADDR on the tun device these values are both updated. However, if SIOCSIFHWADDR is performed on the net device directly (for instance, setting the hw address using ifconfig), the tun device does not get updated. Perhaps the tun.dev_addr field should be removed completely at some point, as it is redundant and net_device.dev_addr can be used anywhere it is used.

@@ -196,7 +196,10 @@ static void tun_net_init(struct net_devi
                dev->set_multicast_list = tun_net_mclist;
 
                ether_setup(dev);
-               random_ether_addr(dev->dev_addr);
+
+               /* random address already created for us by tun_set_iff, use it */
+               memcpy(dev->dev_addr, tun->dev_addr, min(sizeof(tun->dev_addr), sizeof(dev->dev_addr)) );
+
                dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
                break;
        }

@@ -636,6 +639,7 @@ static int tun_chr_ioctl(struct inode *i
                return 0;
 
        case SIOCGIFHWADDR:
+               /* Note: the actual net device's address may be different */
                memcpy(ifr.ifr_hwaddr.sa_data, tun->dev_addr,
                                min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
                if (copy_to_user( argp, &ifr, sizeof ifr))

@@ -643,16 +647,22 @@ static int tun_chr_ioctl(struct inode *i
                return 0;
 
        case SIOCSIFHWADDR:
-               /** Set the character device's hardware address. This is used when
-                * filtering packets being sent from the network device to the character
-                * device. */
-               memcpy(tun->dev_addr, ifr.ifr_hwaddr.sa_data,
-                               min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
-               DBG(KERN_DEBUG "%s: set hardware address: %x:%x:%x:%x:%x:%x\n",
-                               tun->dev->name,
-                               tun->dev_addr[0], tun->dev_addr[1], tun->dev_addr[2],
-                               tun->dev_addr[3], tun->dev_addr[4], tun->dev_addr[5]);
-               return 0;
+               /* try to set the actual net device's hw address */
+               int ret = dev_set_mac_address(tun->dev, &ifr.ifr_hwaddr);
+
+               if (ret == 0) {
+                       /** Set the character device's hardware address. This is used when
+                        * filtering packets being sent from the network device to the character
+                        * device. */
+                       memcpy(tun->dev_addr, ifr.ifr_hwaddr.sa_data,
+                                       min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
+                       DBG(KERN_DEBUG "%s: set hardware address: %x:%x:%x:%x:%x:%x\n",
+                                       tun->dev->name,
+                                       tun->dev_addr[0], tun->dev_addr[1], tun->dev_addr[2],
+                                       tun->dev_addr[3], tun->dev_addr[4], tun->dev_addr[5]);
+               }
+
+               return  ret;
 
        case SIOCADDMULTI:
                /** Add the specified group to the character device's multicast filter

From: Brian Braunstein <[email protected]>

Fixed tun/tap driver's handling of hw addresses. The hw address is stored in both the net_device.dev_addr and tun.dev_addr fields. These fields were not kept synchronized, and in fact weren't even initialized to the same value. Now during both init and when performing SIOCSIFHWADDR on the tun device these values are both updated. However, if SIOCSIFHWADDR is performed on the net device directly (for instance, setting the hw address using ifconfig), the tun device does not get updated. Perhaps the tun.dev_addr field should be removed completely at some point, as it is redundant and net_device.dev_addr can be used anywhere it is used.

@@ -196,7 +196,10 @@ static void tun_net_init(struct net_devi
 		dev->set_multicast_list = tun_net_mclist;
 
 		ether_setup(dev);
-		random_ether_addr(dev->dev_addr);
+
+		/* random address already created for us by tun_set_iff, use it */
+		memcpy(dev->dev_addr, tun->dev_addr, min(sizeof(tun->dev_addr), sizeof(dev->dev_addr)) );
+
 		dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
 		break;
 	}

@@ -636,6 +639,7 @@ static int tun_chr_ioctl(struct inode *i
 		return 0;
 
 	case SIOCGIFHWADDR:
+		/* Note: the actual net device's address may be different */
 		memcpy(ifr.ifr_hwaddr.sa_data, tun->dev_addr,
 				min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
 		if (copy_to_user( argp, &ifr, sizeof ifr))

@@ -643,16 +647,22 @@ static int tun_chr_ioctl(struct inode *i
 		return 0;
 
 	case SIOCSIFHWADDR:
-		/** Set the character device's hardware address. This is used when
-		 * filtering packets being sent from the network device to the character
-		 * device. */
-		memcpy(tun->dev_addr, ifr.ifr_hwaddr.sa_data,
-				min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
-		DBG(KERN_DEBUG "%s: set hardware address: %x:%x:%x:%x:%x:%x\n",
-				tun->dev->name,
-				tun->dev_addr[0], tun->dev_addr[1], tun->dev_addr[2],
-				tun->dev_addr[3], tun->dev_addr[4], tun->dev_addr[5]);
-		return 0;
+		/* try to set the actual net device's hw address */
+		int ret = dev_set_mac_address(tun->dev, &ifr.ifr_hwaddr);
+
+		if (ret == 0) {
+			/** Set the character device's hardware address. This is used when
+			 * filtering packets being sent from the network device to the character
+			 * device. */
+			memcpy(tun->dev_addr, ifr.ifr_hwaddr.sa_data,
+					min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
+			DBG(KERN_DEBUG "%s: set hardware address: %x:%x:%x:%x:%x:%x\n",
+					tun->dev->name,
+					tun->dev_addr[0], tun->dev_addr[1], tun->dev_addr[2],
+					tun->dev_addr[3], tun->dev_addr[4], tun->dev_addr[5]);
+		}
+
+		return  ret;
 
 	case SIOCADDMULTI:
 		/** Add the specified group to the character device's multicast filter