netdev - [PATCH net-next 3/5] net: ipv6: addrconf: Expose IPv6 address labels through netlink

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Date:   Fri, 10 Mar 2023 12:44:56 +0100
From:   Petr Machata <petrm@...dia.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, <netdev@...r.kernel.org>
CC:     David Ahern <dsahern@...nel.org>, Shuah Khan <shuah@...nel.org>,
        "Ido Schimmel" <idosch@...dia.com>,
        Petr Machata <petrm@...dia.com>, <mlxsw@...dia.com>
Subject: [PATCH net-next 3/5] net: ipv6: addrconf: Expose IPv6 address labels through netlink

Support for IPv6 address labels, arbitrary userspace tags associated with
IPv6 addresses, was added in the previous patch. In this patch, expose the
feature through netlink to permit userspace to configure and query address
labels.

An example session with the feature in action:

	# ip address add dev d 2001:db8:1::1/64 label foo
	# ip address show dev d
	4: d: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc [...]
	    link/ether 06:29:74:fd:1f:eb brd ff:ff:ff:ff:ff:ff
	    inet6 2001:db8:1::1/64 scope global foo <--
	    valid_lft forever preferred_lft forever
	    inet6 fe80::429:74ff:fefd:1feb/64 scope link d
	    valid_lft forever preferred_lft forever

	# ip address replace dev d 2001:db8:1::1/64 label bar
	# ip address show dev d
	4: d: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc [...]
	    link/ether 06:29:74:fd:1f:eb brd ff:ff:ff:ff:ff:ff
	    inet6 2001:db8:1::1/64 scope global bar <--
	    valid_lft forever preferred_lft forever
	    inet6 fe80::429:74ff:fefd:1feb/64 scope link d
	    valid_lft forever preferred_lft forever

	# ip address del dev d 2001:db8:1::1/64 label foo
	RTNETLINK answers: Cannot assign requested address
	# ip address del dev d 2001:db8:1::1/64 label bar

Signed-off-by: Petr Machata <petrm@...dia.com>
Reviewed-by: Ido Schimmel <idosch@...dia.com>
---
 net/ipv6/addrconf.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 5f4f16bb6ef0..edd1d08eeadb 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -4671,6 +4671,7 @@ static const struct nla_policy ifa_ipv6_policy[IFA_MAX+1] = {
 	[IFA_RT_PRIORITY]	= { .len = sizeof(u32) },
 	[IFA_TARGET_NETNSID]	= { .type = NLA_S32 },
 	[IFA_PROTO]		= { .type = NLA_U8 },
+	[IFA_LABEL]		= { .type = NLA_STRING, .len = IFNAMSIZ - 1 },
 };
 
 static int
@@ -4681,6 +4682,7 @@ inet6_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
 	struct ifaddrmsg *ifm;
 	struct nlattr *tb[IFA_MAX+1];
 	struct in6_addr *pfx, *peer_pfx;
+	const char *ifa_label;
 	u32 ifa_flags;
 	int err;
 
@@ -4695,11 +4697,12 @@ inet6_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
 		return -EINVAL;
 
 	ifa_flags = tb[IFA_FLAGS] ? nla_get_u32(tb[IFA_FLAGS]) : ifm->ifa_flags;
+	ifa_label = tb[IFA_LABEL] ? nla_data(tb[IFA_LABEL]) : NULL;
 
 	/* We ignore other flags so far. */
 	ifa_flags &= IFA_F_MANAGETEMPADDR;
 
-	return inet6_addr_del(net, ifm->ifa_index, ifa_flags, NULL, pfx,
+	return inet6_addr_del(net, ifm->ifa_index, ifa_flags, ifa_label, pfx,
 			      ifm->ifa_prefixlen);
 }
 
@@ -4915,6 +4918,11 @@ inet6_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
 	else
 		cfg.ifa_flags = ifm->ifa_flags;
 
+	if (tb[IFA_LABEL]) {
+		nla_strscpy(cfg.ifa_label, tb[IFA_LABEL], IFNAMSIZ);
+		cfg.has_ifa_label = true;
+	}
+
 	/* We ignore other flags so far. */
 	cfg.ifa_flags &= IFA_F_NODAD | IFA_F_HOMEADDRESS |
 			 IFA_F_MANAGETEMPADDR | IFA_F_NOPREFIXROUTE |
@@ -4999,7 +5007,9 @@ static inline int inet6_ifaddr_msgsize(void)
 	       + nla_total_size(sizeof(struct ifa_cacheinfo))
 	       + nla_total_size(4)  /* IFA_FLAGS */
 	       + nla_total_size(1)  /* IFA_PROTO */
-	       + nla_total_size(4)  /* IFA_RT_PRIORITY */;
+	       + nla_total_size(4)  /* IFA_RT_PRIORITY */
+	       + nla_total_size(IFNAMSIZ) /* IFA_LABEL */
+	       ;
 }
 
 enum addr_type_t {
@@ -5082,6 +5092,10 @@ static int inet6_fill_ifaddr(struct sk_buff *skb, struct inet6_ifaddr *ifa,
 	    nla_put_u8(skb, IFA_PROTO, ifa->ifa_proto))
 		goto error;
 
+	if (ifa->ifa_label[0] &&
+	    nla_put_string(skb, IFA_LABEL, ifa->ifa_label))
+		goto error;
+
 	nlmsg_end(skb, nlh);
 	return 0;
 
-- 
2.39.0