[PATCH v3 net-next 4/5] geneve: Add dualstack flag to struct geneve_config.

[Kuniyuki Iwashima <kuniyu@google.com>]

When collect metadata mode (IFLA_GENEVE_COLLECT_METADATA) is
enabled, the GENEVE device creates both IPv4 and IPv6 sockets
and bind()s them to wildcard addresses.

The next patch allows creating only one socket bound to a
specific address even when the collect metadata mode is
enabled.

Then, we need a flag to distinguish dualstack GENEVE devices
to detect local address conflict.

Let's add the dualstack flag to struct geneve_config.

IFLA_GENEVE_COLLECT_METADATA processing is moved up in
geneve_nl2info() for the next patch to overwrite dualstack
to false while keeping collect_md true.

Note that IFLA_GENEVE_REMOTE and IFLA_GENEVE_REMOTE6 does not
set cfg->dualstack to false since is_tnl_info_zero() ignores
the wildcard remote address:

  # ip link add geneve0 type geneve external remote 0.0.0.1
  Error: Device is externally controlled, so attributes (VNI, Port, and so on) must not be specified.

  # ip link add geneve0 type geneve external remote 0.0.0.0
  # ss -ua | grep geneve
  UNCONN 0      0            0.0.0.0:geneve      0.0.0.0:*
  UNCONN 0      0                  *:geneve            *:*

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
v2: Don't set cfg->dualstack for IFLA_GENEVE_REMOTE6?
---
 drivers/net/geneve.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index 4f841eced028..3a62d132a8c4 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -73,6 +73,7 @@ struct geneve_dev_node {
 
 struct geneve_config {
 	bool			collect_md;
+	bool			dualstack;
 	bool			use_udp6_rx_checksums;
 	bool			ttl_inherit;
 	bool			gro_hint;
@@ -1108,12 +1109,12 @@ static int geneve_sock_add(struct geneve_dev *geneve, bool ipv6)
 static int geneve_open(struct net_device *dev)
 {
 	struct geneve_dev *geneve = netdev_priv(dev);
-	bool metadata = geneve->cfg.collect_md;
+	bool dualstack = geneve->cfg.dualstack;
 	bool ipv4, ipv6;
 	int ret = 0;
 
-	ipv6 = geneve->cfg.info.mode & IP_TUNNEL_INFO_IPV6 || metadata;
-	ipv4 = !ipv6 || metadata;
+	ipv6 = geneve->cfg.info.mode & IP_TUNNEL_INFO_IPV6 || dualstack;
+	ipv4 = !ipv6 || dualstack;
 #if IS_ENABLED(CONFIG_IPV6)
 	if (ipv6) {
 		ret = geneve_sock_add(geneve, true);
@@ -1906,6 +1907,16 @@ static int geneve_nl2info(struct nlattr *tb[], struct nlattr *data[],
 	struct ip_tunnel_info *info = &cfg->info;
 	int attrtype;
 
+	if (data[IFLA_GENEVE_COLLECT_METADATA]) {
+		if (changelink) {
+			attrtype = IFLA_GENEVE_COLLECT_METADATA;
+			goto change_notsup;
+		}
+
+		cfg->collect_md = true;
+		cfg->dualstack = true;
+	}
+
 	if (data[IFLA_GENEVE_REMOTE] && data[IFLA_GENEVE_REMOTE6]) {
 		NL_SET_ERR_MSG(extack,
 			       "Cannot specify both IPv4 and IPv6 Remote addresses");
@@ -2025,14 +2036,6 @@ static int geneve_nl2info(struct nlattr *tb[], struct nlattr *data[],
 		cfg->port_max = ntohs(p->high);
 	}
 
-	if (data[IFLA_GENEVE_COLLECT_METADATA]) {
-		if (changelink) {
-			attrtype = IFLA_GENEVE_COLLECT_METADATA;
-			goto change_notsup;
-		}
-		cfg->collect_md = true;
-	}
-
 	if (data[IFLA_GENEVE_UDP_CSUM]) {
 		if (changelink) {
 			attrtype = IFLA_GENEVE_UDP_CSUM;
@@ -2153,6 +2156,7 @@ static int geneve_newlink(struct net_device *dev,
 		.use_udp6_rx_checksums = false,
 		.ttl_inherit = false,
 		.collect_md = false,
+		.dualstack = false,
 		.port_min = 1,
 		.port_max = USHRT_MAX,
 	};
@@ -2382,6 +2386,7 @@ struct net_device *geneve_dev_create_fb(struct net *net, const char *name,
 		.use_udp6_rx_checksums = true,
 		.ttl_inherit = false,
 		.collect_md = true,
+		.dualstack = true,
 		.port_min = 1,
 		.port_max = USHRT_MAX,
 	};
-- 
2.54.0.746.g67dd491aae-goog