Messages in this thread | | | From | Mark Smith <> | Date | Mon, 13 Sep 2021 01:47:30 +1000 | Subject | Re: [PATCH] net: ipv6: don't generate link-local address in any addr_gen_mode |
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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:
RFC4291, "IP Version 6 Addressing Architecture"
"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)."
Regards, Mark.
On Fri, 10 Sept 2021 at 05:13, David Ahern <dsahern@gmail.com> wrote: > > On 9/9/21 12:20 AM, Lorenzo Colitti wrote: > >> I think another addr_gen_mode is better than a separate sysctl. It looks > >> like IN6_ADDR_GEN_MODE_STABLE_PRIVACY and IN6_ADDR_GEN_MODE_RANDOM are > >> the ones used for RAs, so add something like: > >> > >> IN6_ADDR_GEN_MODE_STABLE_PRIVACY_NO_LLA, > >> IN6_ADDR_GEN_MODE_RANDOM_NO_LLA, > > > > I think the real requirement here (which wasn't clear in this thread) > > is that the network needs to control the interface ID (i.e., the > > bottom 64 bits) of the link-local address, but the device is free to > > use whatever interface IDs to form global addresses. See: > > https://www.etsi.org/deliver/etsi_ts/129000_129099/129061/15.03.00_60/ts_129061v150300p.pdf > > > > How do you think that would best be implemented? > > There is an established paradigm for configuring how an IPv6 address is > created or whether it is created at all - the IFLA_INET6_ADDR_GEN_MODE > attribute. > > > > > 1. The actual interface ID could be passed in using IFLA_INET6_TOKEN, > > but there is only one token, so that would cause all future addresses > > to use the token, disabling things like privacy addresses (bad). > > 2. We could add new IN6_ADDR_GEN_MODE_STABLE_PRIVACY_LL_TOKEN, > > IN6_ADDR_GEN_MODE_RANDOM_LL_TOKEN, etc., but we'd need to add one such > > mode for every new mode we add. > > 3. We could add a separate sysctl for the link-local address, but you > > said that per-device sysctls aren't free. > > per-device sysctl's are one of primary causes of per netdev memory usage. > > Besides that there is no reason to add complexity by having a link > attribute and a sysctl for this feature. > > > 4. We could change the behaviour so that if the user configures a > > token and then sets IN6_ADDR_GEN_MODE_*, then we use the token only > > for the link-local address. But that would impact backwards > > compatibility. > > > > Thoughts? > > We can have up to 255 ADDR_GEN_MODEs (GEN_MODE is a u8). There is > established code for handling the attribute and changes to it. Let's > reuse it.
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