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net: add sysctl to disable rfc4862 5.5.3e lifetime handling

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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>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20230925214711.959704-1-prohr@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Patrick Rohr 2023-09-25 14:47:11 -07:00 committed by Jakub Kicinski
parent 8989682a1c
commit 473267a491
3 changed files with 37 additions and 13 deletions
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11
Documentation/networking/ip-sysctl.rst
View File

@ -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.

1
include/linux/ipv6.h
View File

@ -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;
};

38
net/ipv6/addrconf.c
View File

@ -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",