Messages in this thread | | | From | Mark Smith <> | Date | Tue, 14 Sep 2021 01:22:28 +1000 | Subject | Re: [PATCH] net: ipv6: don't generate link-local address in any addr_gen_mode |
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Hi Lorenzo,
On Mon, 13 Sept 2021 at 19:38, Lorenzo Colitti <lorenzo@google.com> wrote: > > On Mon, Sep 13, 2021 at 12:47 AM Mark Smith <markzzzsmith@gmail.com> wrote: > > This is all going in the wrong direction. Link-local addresses are not > > optional on an interface, all IPv6 enabled interfaces are required to > > have one: > > The original patch did indeed disable the generation of the link-local > address, but that patch was rejected. It sounds like the right > approach here is to provide two new addressing modes: > > IN6_ADDR_GEN_MODE_RANDOM_LL_TOKEN > IN6_ADDR_GEN_MODE_STABLE_PRIVACY_LL_TOKEN > > which would form the link-local address from the token passed in via > IFLA_INET6_TOKEN, but would form non-link-local addresses (e.g., > global addresses) via the specified means (either random or stable > privacy). I haven't looked at how to do that yet though.
I think there is a broader issue here.
If RFC7217 is used to generate the Link-Local address, then the likelihood of the Link-Local address being a duplicate with the GGSN is very low, because RFC7217 uses a function such as SHA-1 or SHA-256. RFC7217 also performs DAD just in case, and triggers RFC7217 again if a duplicate does occur.
RFC8064 recommends RFC7217 for all stable IPv6 addresses by default now, which includes Link-Local addresses.
Following RFC8064 by Implementing RFC7217 for all stable IPv6 addresses the Linux kernel generates would solve both the 3GPP's duplicate Link-Local address concern, and also make the Linux kernel compliant with the latest SLAAC recommendation for default IIDs and stable IPv6 addresses.
Regards, Mark.
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