Tap driver incorrectly uses globally unique ID when "mac=fixed" is specified

https://bugs.dpdk.org/show_bug.cgi?id=1198

Bug ID: 1198
Summary: Tap driver incorrectly uses globally unique ID when
"mac=fixed" is specified
Product: DPDK
Version: 23.03
Hardware: All
OS: All
Status: UNCONFIRMED
Severity: normal
Priority: Normal
Component: core
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---

When the tap driver is loaded and the user selects the optional "mac=fixed" setting, the tap driver incorrectly uses a globally unique EUI-48 identifier (as documented in RFC 7042). Since this is a locally generated ID, the Local bit in the MAC address should be set to 1.

The following change is suggested:

index 2f7417bddd..07df0d35a2 100644
@@ -34,14 +34,14 @@ Using the option ``mac=fixed`` you can create a fixed known

MAC address::

The MAC address will have a fixed value with the last octet incrementing by
one
for each interface string containing ``mac=fixed``. The MAC address is
formatted
-as 00:'d':'t':'a':'p':[00-FF]. Convert the characters to hex and you get the -actual MAC address: ``00:64:74:61:70:[00-FF]``.
+as 02:'d':'t':'a':'p':[00-FF]. Convert the characters to hex and you get the +actual MAC address: ``02:64:74:61:70:[00-FF]``.

- --vdev=net_tap0,mac="00:64:74:61:70:11"
+ --vdev=net_tap0,mac="02:64:74:61:70:11"

The MAC address will have a user value passed as string. The MAC address is in format with delimiter ``:``. The string is byte converted to hex and you get
-the actual MAC address: ``00:64:74:61:70:11``.
+the actual MAC address: ``02:64:74:61:70:11``.

It is possible to specify a remote netdevice to capture packets from by adding ``remote=foo1``, for example::

index 8c50801fd4..02f8066635 100644
@@ -2280,8 +2280,8 @@ set_mac_type(const char *key __rte_unused,
        if (!strncasecmp(ETH_TAP_MAC_FIXED, value, strlen(ETH_TAP_MAC_FIXED)))

{
                static int iface_idx;

-               /* fixed mac = 00:64:74:61:70:<iface_idx> */
-               memcpy((char *)user_mac->addr_bytes, "\0dtap",
+               /* fixed mac = 02:64:74:61:70:<iface_idx> */
+               memcpy((char *)user_mac->addr_bytes, "\002dtap",
                        RTE_ETHER_ADDR_LEN);
                user_mac->addr_bytes[RTE_ETHER_ADDR_LEN - 1] =
                        iface_idx++ + '0';

b/examples/ipsec-secgw/test/common_defs.sh
index 3ef06bc761..6e04ffc1a6 100644

@@ -26,7 +26,7 @@ fi
 
 LOCAL_IFACE=dtap0
 
-LOCAL_MAC="00:64:74:61:70:30"
+LOCAL_MAC="02:64:74:61:70:30"
 
 REMOTE_IPV4=192.168.31.14
 LOCAL_IPV4=192.168.31.92

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