Messages in this thread | | | Subject | Re: [PATCH] net: ipv6: don't generate link-local address in any addr_gen_mode | From | David Ahern <> | Date | Thu, 9 Sep 2021 13:12:37 -0600 |
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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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