Re: [PATCH net-next v2] net: add sysctl to disable rfc4862 5.5.3e lifetime handling

[Jiri Pirko <jiri@resnulli.us>]

Tue, Sep 12, 2023 at 03:44:25PM CEST, prohr@google.com wrote:
>This change adds a sysctl to opt-out of RFC4862 section 5.5.3e's valid
>lifetime derivation mechanism.
>
>RFC4862 section 5.5.3e prescribes that the valid lifetime in a Router
>Advertisement PIO shall be ignored if it less than 2 hours and to reset
>the lifetime of the corresponding address to 2 hours. An in-progress
>6man draft (see draft-ietf-6man-slaac-renum-07 section 4.2) is currently
>looking to remove this mechanism. While this draft has not been moving
>particularly quickly for other reasons, there is widespread consensus on
>section 4.2 which updates RFC4862 section 5.5.3e.
>
>Cc: Maciej Żenczykowski <maze@google.com>
>Cc: Lorenzo Colitti <lorenzo@google.com>
>Cc: Jen Linkova <furry@google.com>
>Signed-off-by: Patrick Rohr <prohr@google.com>
>---
> Documentation/networking/ip-sysctl.rst | 11 ++++++++
> include/linux/ipv6.h                   |  1 +
> net/ipv6/addrconf.c                    | 38 +++++++++++++++++---------
> 3 files changed, 37 insertions(+), 13 deletions(-)
>
>diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
>index a66054d0763a..7f21877e3f78 100644
>--- a/Documentation/networking/ip-sysctl.rst
>+++ b/Documentation/networking/ip-sysctl.rst
>@@ -2304,6 +2304,17 @@ accept_ra_pinfo - BOOLEAN
> 		- enabled if accept_ra is enabled.
> 		- disabled if accept_ra is disabled.
> 
>+ra_pinfo_rfc4862_5_5_3e - BOOLEAN

This is very odd sysctl name.


>+	Use RFC4862 Section 5.5.3e to determine the valid lifetime of
>+	an address matching a prefix sent in a Router Advertisement
>+	Prefix Information Option.
>+
>+	- If enabled, RFC4862 section 5.5.3e is used to determine
>+	  the valid lifetime of the address.
>+	- If disabled, the PIO valid lifetime will always be honored.

Can't you reverse the logic and call it something like:
ra_honor_pio_lifetime
?