Re: [PATCH] net: ipv6: don't generate link-local address in any addr_gen_mode
flat view
From: David Ahern <hidden>
Date: 2021-09-09 19:12:42
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linux-mediatek, lkml, netdev
On 9/9/21 12:20 AM, Lorenzo Colitti wrote:
quoted
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. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel