netdev - Re: net: ipv6: Fix a bug in ndisc_send_ns when netdev only has a global address

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Message-ID: <93c401b9-bf8b-4d49-9c3b-72d09073444e@cn.fujitsu.com>
Date:   Tue, 30 Jul 2019 17:39:10 +0800
From:   Su Yanjun <suyj.fnst@...fujitsu.com>
To:     Mark Smith <markzzzsmith@...il.com>, <netdev@...r.kernel.org>
Subject: Re: net: ipv6: Fix a bug in ndisc_send_ns when netdev only has a
 global address


在 2019/7/30 16:15, Mark Smith 写道:
> Hi,
>
> I'm not subscribed to the Linux netdev mailing list, so I can't
> directly reply to the patch email.
>
> This patch is not the correct solution to this issue.
>
> Per RFC 4291 "IP Version 6 Addressing Architecture", all IPv6
> interfaces are required to have Link-Local addresses, so therefore
> there should always be a link-local address available to use as the
> source address for an ND NS.

In linux implementation, one interface may have no link local address if 
kernel config

*addr_gen_mode* is set to IN6_ADDR_GEN_MODE_NONE. My patch is to fix 
this problem.

And what you say is related to the lo interface.  I'm not sure whether 
the lo interface needs a ll adreess.

IMO the ll address is used to get l2 address by sending ND ns. The lo is 
very special.

Thanks

Su

>
> "2.1. Addressing Model"
>
> ...
>
> "All interfaces are required to have at least one Link-Local unicast
>     address (see Section 2.8 for additional required addresses)."
>
> I have submitted a more specific bug regarding no Link-Local
> address/prefix on the Linux kernel loopback interface through RedHat
> bugzilla as I use Fedora 30, however it doesn't seem to have been
> looked at yet.
>
> "Loopback network interface does not have a Link Local address,
> contrary to RFC 4291"
> https://bugzilla.redhat.com/show_bug.cgi?id=1706709
>
>
> Thanks very much,
> Mark.
>
>