From 473267a4911f2469722c74ca58087d951072f72a Mon Sep 17 00:00:00 2001 From: Patrick Rohr Date: Mon, 25 Sep 2023 14:47:11 -0700 Subject: [PATCH] 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 --- 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 5bfa1837968ce..f7dfde3b09a96 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -2311,6 +2311,17 @@ accept_ra_pinfo - BOOLEAN - enabled if accept_ra is enabled. - disabled if accept_ra is disabled. +ra_honor_pio_life - BOOLEAN + Whether to 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, the PIO valid lifetime will always be honored. + - If disabled, RFC4862 section 5.5.3e is used to determine + the valid lifetime of the address. + + Default: 0 (disabled) + accept_ra_rt_info_min_plen - INTEGER Minimum prefix length of Route Information in RA. diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h index e400ff757f136..5e605e384aac8 100644 --- a/include/linux/ipv6.h +++ b/include/linux/ipv6.h @@ -82,6 +82,7 @@ struct ipv6_devconf { __u32 ioam6_id_wide; __u8 ioam6_enabled; __u8 ndisc_evict_nocarrier; + __u8 ra_honor_pio_life; struct ctl_table_header *sysctl_header; }; diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 0b6ee962c84e2..c2d471ad7922c 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",