From 473267a4911f2469722c74ca58087d951072f72a Mon Sep 17 00:00:00 2001 From: Patrick Rohr Date: Mon, 25 Sep 2023 14:47:11 -0700 Subject: net: add sysctl to disable rfc4862 5.5.3e lifetime handling MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Cc: Lorenzo Colitti Cc: Jen Linkova Signed-off-by: Patrick Rohr Reviewed-by: Jiri Pirko Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20230925214711.959704-1-prohr@google.com Signed-off-by: Jakub Kicinski --- net/ipv6/addrconf.c | 38 +++++++++++++++++++++++++------------- 1 file changed, 25 insertions(+), 13 deletions(-) (limited to 'net/ipv6') diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 0b6ee962c84e..c2d471ad7922 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -236,6 +236,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = { .ioam6_id = IOAM6_DEFAULT_IF_ID, .ioam6_id_wide = IOAM6_DEFAULT_IF_ID_WIDE, .ndisc_evict_nocarrier = 1, + .ra_honor_pio_life = 0, }; static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { @@ -297,6 +298,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { .ioam6_id = IOAM6_DEFAULT_IF_ID, .ioam6_id_wide = IOAM6_DEFAULT_IF_ID_WIDE, .ndisc_evict_nocarrier = 1, + .ra_honor_pio_life = 0, }; /* Check if link is ready: is it up and is a valid qdisc available */ @@ -2657,22 +2659,23 @@ int addrconf_prefix_rcv_add_addr(struct net *net, struct net_device *dev, stored_lft = ifp->valid_lft - (now - ifp->tstamp) / HZ; else stored_lft = 0; - if (!create && stored_lft) { + + /* RFC4862 Section 5.5.3e: + * "Note that the preferred lifetime of the + * corresponding address is always reset to + * the Preferred Lifetime in the received + * Prefix Information option, regardless of + * whether the valid lifetime is also reset or + * ignored." + * + * So we should always update prefered_lft here. + */ + update_lft = !create && stored_lft; + + if (update_lft && !in6_dev->cnf.ra_honor_pio_life) { const u32 minimum_lft = min_t(u32, stored_lft, MIN_VALID_LIFETIME); valid_lft = max(valid_lft, minimum_lft); - - /* RFC4862 Section 5.5.3e: - * "Note that the preferred lifetime of the - * corresponding address is always reset to - * the Preferred Lifetime in the received - * Prefix Information option, regardless of - * whether the valid lifetime is also reset or - * ignored." - * - * So we should always update prefered_lft here. - */ - update_lft = 1; } if (update_lft) { @@ -6846,6 +6849,15 @@ static const struct ctl_table addrconf_sysctl[] = { .mode = 0644, .proc_handler = proc_dointvec, }, + { + .procname = "ra_honor_pio_life", + .data = &ipv6_devconf.ra_honor_pio_life, + .maxlen = sizeof(u8), + .mode = 0644, + .proc_handler = proc_dou8vec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, #ifdef CONFIG_IPV6_ROUTER_PREF { .procname = "accept_ra_rtr_pref", -- cgit v1.2.3