"Jason A. Donenfeld" <Jason@xxxxxxxxx> writes: > On Thu, Jan 13, 2022 at 2:50 PM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote: >> > Then, at some point down the road, we can talk about removing >> > CONFIG_NET_OBSOLETE_INSECURE_ADDRCONF_HASH too. >> > >> >> What is the point of having CONFIG_OLD_N_CRUSTY if all distros are >> going to enable it indefinitely? > > I think there's probably some combination of > CONFIG_NET_OBSOLETE_INSECURE_ADDRCONF_HASH and CONFIG_OLD_N_CRUSTY and > maybe even a CONFIG_GOD_MURDERS_KITTENS that might be sufficiently > disincentivizing? Or this ties into other general ideas on a gradual > obsolescence->removal flow for things. Making it a compile-time switch doesn't really solve anything, though. It'll need to be a runtime switch for people to be able to opt-in to the new behaviour; otherwise there would still be a flag day when distributions switch on the new config option. I don't think there's any reason to offload this decision on distributions either: there's clearly a "best option" here, absent any backwards compatibility concerns. So it's on us to design a proper transition mechanism. Defaulting to SHA1 when stable_secret is set, as Ard suggested, sounds like a reasonable default; then we only need a single new value for addr_gen_mode to opt-in to using blake2s even when setting the stable_secret. -Toke
