[Bug 277128] IPV6 public address lost after networking driver reload and attaching a new network interface

From: <bugzilla-noreply_at_freebsd.org>
Date: Sun, 18 Feb 2024 12:36:29 UTC 
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=277128

            Bug ID: 277128
           Summary: IPV6 public address lost after networking driver
                    reload and attaching a new network interface
           Product: Base System
           Version: Unspecified
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Many People
          Priority: ---
         Component: kern
          Assignee: bugs@FreeBSD.org
          Reporter: osamaabb@amazon.com

Issue: IPV6 Public address lost after reloading a network driver OR attaching a
new interface on a running instance
Reproduction:
The issue was reproduced in aws EC2 services, it reproduces over all regions:
Region: us-west-2 (Oregon)
AMI: ami-0e1d8ff3b9c3f2571
Instance: c5.12xlrage

Reproduction steps:
1- Create a subnet that allows ipv6 addresses and make sure to tick "Enable
auto-assign IPv6 address" in the subnet settings

2- Create a new interface in the newly created subnet

3- Attached the interface to the instance - This interface will be seen as ena0
in the upcoming examples

Issue No. 1:
============

At this point you'll see the newly attached interface (ena0) is attached but
does not have a public IPv6 address:

root@freebsd:/home/ec2-user # ifconfig
enas0: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9001
        options=200423<RXCSUM,TXCSUM,JUMBO_MTU,LRO,RXCSUM_IPV6>
        ether 02:da:b6:58:d9:d3
        inet6 fe80::da:b6ff:fe58:d9d3%enas0 prefixlen 64 scopeid 0x1
        inet 172.31.30.153 netmask 0xfffff000 broadcast 172.31.31.255
        media: Ethernet autoselect (Unknown <full-duplex>)
        status: active
        nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
ena0: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9001
        options=200423<RXCSUM,TXCSUM,JUMBO_MTU,LRO,RXCSUM_IPV6>
        ether 02:12:77:45:cf:75
        inet6 fe80::12:77ff:fe45:cf75%ena0 prefixlen 64 scopeid 0x3
        inet 172.31.207.24 netmask 0xfffff000 broadcast 172.31.207.255
        media: Ethernet autoselect (Unknown <full-duplex>)
        status: active
        nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>

Reboot the instance, you'll see that the new interface will get a public IPv6
address:

ec2-user@freebsd:~ $ ifconfig
enas0: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9001
        options=200423<RXCSUM,TXCSUM,JUMBO_MTU,LRO,RXCSUM_IPV6>
        ether 02:da:b6:58:d9:d3
        inet6 fe80::da:b6ff:fe58:d9d3%enas0 prefixlen 64 scopeid 0x1
        inet 172.31.30.153 netmask 0xfffff000 broadcast 172.31.31.255
        media: Ethernet autoselect (Unknown <full-duplex>)
        status: active
        nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
ena0: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9001
        options=200423<RXCSUM,TXCSUM,JUMBO_MTU,LRO,RXCSUM_IPV6>
        ether 02:12:77:45:cf:75
        inet6 fe80::12:77ff:fe45:cf75%ena0 prefixlen 64 scopeid 0x2
        inet6 2600:1f14:c0:8803:618:da09:7da9:310 prefixlen 128
        inet 172.31.207.24 netmask 0xfffff000 broadcast 172.31.207.255
        media: Ethernet autoselect (Unknown <full-duplex>)
        status: active
        nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>


Issue No. 2:
============
Reload the driver by running kldunload if_ena.ko && kldload ./if_ena.ko and
you'll see that the public IPv6 address is lost

ec2-user@freebsd:~ $ ifconfig
enas0: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9001
        options=200423<RXCSUM,TXCSUM,JUMBO_MTU,LRO,RXCSUM_IPV6>
        ether 02:da:b6:58:d9:d3
        inet6 fe80::da:b6ff:fe58:d9d3%enas0 prefixlen 64 scopeid 0x1
        inet 172.31.30.153 netmask 0xfffff000 broadcast 172.31.31.255
        media: Ethernet autoselect (Unknown <full-duplex>)
        status: active
        nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
ena0: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9001
        options=200423<RXCSUM,TXCSUM,JUMBO_MTU,LRO,RXCSUM_IPV6>
        ether 02:12:77:45:cf:75
        inet6 fe80::12:77ff:fe45:cf75%ena0 prefixlen 64 scopeid 0x2
        inet6 2600:1f14:c0:8803:618:da09:7da9:310 prefixlen 128
        inet 172.31.207.24 netmask 0xfffff000 broadcast 172.31.207.255
        media: Ethernet autoselect (Unknown <full-duplex>)
        status: active
        nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>


-------Reboot-------

root@freebsd:/home/ec2-user/fix-flag # ifconfig
enas0: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9001
        options=200423<RXCSUM,TXCSUM,JUMBO_MTU,LRO,RXCSUM_IPV6>
        ether 02:da:b6:58:d9:d3
        inet6 fe80::da:b6ff:fe58:d9d3%enas0 prefixlen 64 scopeid 0x1
        inet 172.31.30.153 netmask 0xfffff000 broadcast 172.31.31.255
        media: Ethernet autoselect (Unknown <full-duplex>)
        status: active
        nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
ena0: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9001
        options=200423<RXCSUM,TXCSUM,JUMBO_MTU,LRO,RXCSUM_IPV6>
        ether 02:12:77:45:cf:75
        inet6 fe80::12:77ff:fe45:cf75%ena0 prefixlen 64 scopeid 0x2
        inet 172.31.207.24 netmask 0xfffff000 broadcast 172.31.207.255
        media: Ethernet autoselect (Unknown <full-duplex>)
        status: active
        nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>



Looked at the tcpdump results and saw no dhcpv6 requests
Tried to restart the router solicitation daemon, saw router advertisement
messages but still no IPV6

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