[PATCH] net/tap: Set locally administered bit with a fixed MAC address

[PATCH] net/tap: Set locally administered bit with a fixed MAC address

[David Christensen]

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) of
00:64:74:61:70:<iface_idx>. Since this is a locally generated ID,
the Local bit in the MAC address should be set to 1, resulting in
the new address 02:64:74:61:70:<iface_idx>.

Bugzilla ID: 1198

Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>
---
 doc/guides/nics/tap.rst                  | 8 ++++----
 drivers/net/tap/rte_eth_tap.c            | 4 ++--
 examples/ipsec-secgw/test/common_defs.sh | 2 +-
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/doc/guides/nics/tap.rst b/doc/guides/nics/tap.rst
index 2f7417bddd..07df0d35a2 100644
--- a/doc/guides/nics/tap.rst
+++ b/doc/guides/nics/tap.rst
@@ -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::
diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
index 089ac202fa..bf98f75559 100644
--- a/drivers/net/tap/rte_eth_tap.c
+++ b/drivers/net/tap/rte_eth_tap.c
@@ -2303,8 +2303,8 @@ 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';
diff --git a/examples/ipsec-secgw/test/common_defs.sh b/examples/ipsec-secgw/test/common_defs.sh
index 3ef06bc761..6e04ffc1a6 100644
--- a/examples/ipsec-secgw/test/common_defs.sh
+++ b/examples/ipsec-secgw/test/common_defs.sh
@@ -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
-- 
2.31.1

Re: [PATCH] net/tap: Set locally administered bit with a fixed MAC address

[Stephen Hemminger]

On Tue, 25 Apr 2023 16:58:06 -0400
David Christensen <drc@linux.vnet.ibm.com> wrote:

> 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) of
> 00:64:74:61:70:<iface_idx>. Since this is a locally generated ID,
> the Local bit in the MAC address should be set to 1, resulting in
> the new address 02:64:74:61:70:<iface_idx>.
> 
> Bugzilla ID: 1198
> 
> Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>

Acked-by: Stephen Hemminger <stephen@networkplumber.org>

Re: [PATCH] net/tap: Set locally administered bit with a fixed MAC address

[Ferruh Yigit]

On 4/26/2023 1:39 AM, Stephen Hemminger wrote:
> On Tue, 25 Apr 2023 16:58:06 -0400
> David Christensen <drc@linux.vnet.ibm.com> wrote:
> 
>> 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) of
>> 00:64:74:61:70:<iface_idx>. Since this is a locally generated ID,
>> the Local bit in the MAC address should be set to 1, resulting in
>> the new address 02:64:74:61:70:<iface_idx>.
>>
>> Bugzilla ID: 1198
>>
>> Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>
> 
> Acked-by: Stephen Hemminger <stephen@networkplumber.org>
> 


    Bugzilla ID: 1198
    Fixes: f6921783fee6 ("net/tap: add support for fixed MAC addresses")
    Cc: stable@dpdk.org

Acked-by: Ferruh Yigit <ferruh.yigit@amd.com>

Applied to dpdk-next-net/main, thanks.


Dropped 'examples/ipsec-secgw/test/common_defs.sh' change while merging,
although it is a minor change can you please send a separate patch for it?