Messages in this thread | | | From | Lorenzo Colitti <> | Date | Thu, 9 Sep 2021 15:20:51 +0900 | Subject | Re: [PATCH] net: ipv6: don't generate link-local address in any addr_gen_mode |
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David,
sorry for reviving this discussion, but it felt better than starting a new thread about this. We (Android) added a vendor hook for this, but IMO that's the wrong solution and I think we'd still like to see this fixed the right way.
> 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?
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. 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?
Cheers, Lorenzo
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