Add support for PIO p flag

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@google.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Cc: David Lamparter <equinox@opensourcerouting.org>
Cc: Simon Horman <horms@kernel.org>
Signed-off-by: Patrick Rohr <prohr@google.com>
Reviewed-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 3616389c8c2df233cd6176f3f94cfd44921f5c43..eacf8983e2307476895a8def7363375f2af36d9d 100644 (file)
--- 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 383a0ea2ab9131e685822e5df506582802642e84..a6e2aadbb91bd3bc788b5df5e4df34c859352167 100644 (file)
--- 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 62a407db1bf5ff6dd3298077e05e636ccc2ff97b..b18e81f0c9e1a9c07bfee9d13c295e83d3f6bf2b 100644 (file)
--- 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 f70d8757af1a42f58d08c790610cdb057e052727..c87d008aefa4cc4dfeaf9269034efb840d4222e9 100644 (file)
--- 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;
 
        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",