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Message-ID: <CANP3RGd1iv12GMVrm+HxhNJcofJGFc96z+Or6kLheV1JeAx2wA@mail.gmail.com>
Date: Mon, 29 Jul 2024 17:06:54 -0700
From: Maciej Żenczykowski <maze@...gle.com>
To: Patrick Rohr <prohr@...gle.com>
Cc: "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Jonathan Corbet <corbet@....net>,
David Ahern <dsahern@...nel.org>, netdev@...r.kernel.org, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, Lorenzo Colitti <lorenzo@...gle.com>,
David Lamparter <equinox@...nsourcerouting.org>, Simon Horman <horms@...nel.org>
Subject: Re: [PATCH net-next v2] Add support for PIO p flag
On Mon, Jul 29, 2024 at 3:01 PM Patrick Rohr <prohr@...gle.com> wrote:
>
> draft-ietf-6man-pio-pflag is adding a new flag to the Prefix Information
> Option to signal that the network can allocate a unique IPv6 prefix per
> client via DHCPv6-PD (see draft-ietf-v6ops-dhcp-pd-per-device).
>
> When ra_honor_pio_pflag is enabled, the presence of a P-flag causes
> SLAAC autoconfiguration to be disabled for that particular PIO.
>
> An automated test has been added in Android (r.android.com/3195335) to
> go along with this change.
>
> Cc: Maciej Żenczykowski <maze@...gle.com>
> Cc: Lorenzo Colitti <lorenzo@...gle.com>
> Cc: David Lamparter <equinox@...nsourcerouting.org>
> Cc: Simon Horman <horms@...nel.org>
> Signed-off-by: Patrick Rohr <prohr@...gle.com>
> ---
> Documentation/networking/ip-sysctl.rst | 14 ++++++++++++++
> include/linux/ipv6.h | 1 +
> include/net/addrconf.h | 10 +++++++---
> net/ipv6/addrconf.c | 15 ++++++++++++++-
> 4 files changed, 36 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
> index 3616389c8c2d..eacf8983e230 100644
> --- a/Documentation/networking/ip-sysctl.rst
> +++ b/Documentation/networking/ip-sysctl.rst
> @@ -2362,6 +2362,20 @@ ra_honor_pio_life - BOOLEAN
>
> Default: 0 (disabled)
>
> +ra_honor_pio_pflag - BOOLEAN
> + The Prefix Information Option P-flag indicates the network can
> + allocate a unique IPv6 prefix per client using DHCPv6-PD.
> + This sysctl can be enabled when a userspace DHCPv6-PD client
> + is running to cause the P-flag to take effect: i.e. the
> + P-flag suppresses any effects of the A-flag within the same
> + PIO. For a given PIO, P=1 and A=1 is treated as A=0.
> +
> + - If disabled, the P-flag is ignored.
> + - If enabled, the P-flag will disable SLAAC autoconfiguration
> + for the given Prefix Information Option.
> +
> + 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 383a0ea2ab91..a6e2aadbb91b 100644
> --- a/include/linux/ipv6.h
> +++ b/include/linux/ipv6.h
> @@ -89,6 +89,7 @@ struct ipv6_devconf {
> __u8 ioam6_enabled;
> __u8 ndisc_evict_nocarrier;
> __u8 ra_honor_pio_life;
> + __u8 ra_honor_pio_pflag;
>
> struct ctl_table_header *sysctl_header;
> };
> diff --git a/include/net/addrconf.h b/include/net/addrconf.h
> index 62a407db1bf5..b18e81f0c9e1 100644
> --- a/include/net/addrconf.h
> +++ b/include/net/addrconf.h
> @@ -37,10 +37,14 @@ struct prefix_info {
> struct __packed {
> #if defined(__BIG_ENDIAN_BITFIELD)
> __u8 onlink : 1,
> - autoconf : 1,
> - reserved : 6;
> + autoconf : 1,
> + routeraddr : 1,
> + preferpd : 1,
> + reserved : 4;
> #elif defined(__LITTLE_ENDIAN_BITFIELD)
> - __u8 reserved : 6,
> + __u8 reserved : 4,
> + preferpd : 1,
> + routeraddr : 1,
> autoconf : 1,
> onlink : 1;
> #else
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index 55a0fd589fc8..4febf679a435 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -239,6 +239,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = {
> .ioam6_id_wide = IOAM6_DEFAULT_IF_ID_WIDE,
> .ndisc_evict_nocarrier = 1,
> .ra_honor_pio_life = 0,
> + .ra_honor_pio_pflag = 0,
> };
>
> static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
> @@ -302,6 +303,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
> .ioam6_id_wide = IOAM6_DEFAULT_IF_ID_WIDE,
> .ndisc_evict_nocarrier = 1,
> .ra_honor_pio_life = 0,
> + .ra_honor_pio_pflag = 0,
> };
>
> /* Check if link is ready: is it up and is a valid qdisc available */
> @@ -2762,6 +2764,7 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
> u32 addr_flags = 0;
> struct inet6_dev *in6_dev;
> struct net *net = dev_net(dev);
> + bool ignore_autoconf = false;
This ' = false' appears to be spurious (as ignore_autoconf is only
read after being written), but is of course harmless.
Reviewed-by: Maciej Żenczykowski <maze@...gle.com>
> pinfo = (struct prefix_info *) opt;
>
> @@ -2864,7 +2867,8 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
>
> /* Try to figure out our local address for this prefix */
>
> - if (pinfo->autoconf && in6_dev->cnf.autoconf) {
> + ignore_autoconf = READ_ONCE(in6_dev->cnf.ra_honor_pio_pflag) && pinfo->preferpd;
> + if (pinfo->autoconf && in6_dev->cnf.autoconf && !ignore_autoconf) {
> struct in6_addr addr;
> bool tokenized = false, dev_addr_generated = false;
>
> @@ -6926,6 +6930,15 @@ static const struct ctl_table addrconf_sysctl[] = {
> .extra1 = SYSCTL_ZERO,
> .extra2 = SYSCTL_ONE,
> },
> + {
> + .procname = "ra_honor_pio_pflag",
> + .data = &ipv6_devconf.ra_honor_pio_pflag,
> + .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",
> --
> 2.46.0.rc1.232.g9752f9e123-goog
>
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