ieee802154: Give the user the association list

Upon request, we must be able to provide to the user the list of
associations currently in place. Let's add a new netlink command and
attribute for this purpose.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Stefan Schmidt <stefan@datenfreihafen.org>
Acked-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/linux-wpan/20230927181214.129346-12-miquel.raynal@bootlin.com

include/net/nl802154.h

@@ -81,6 +81,7 @@ enum nl802154_commands {
 	NL802154_CMD_ASSOCIATE,
 	NL802154_CMD_DISASSOCIATE,
 	NL802154_CMD_SET_MAX_ASSOCIATIONS,
+	NL802154_CMD_LIST_ASSOCIATIONS,
 
 	/* add new commands above here */
 
@@ -151,6 +152,7 @@ enum nl802154_attrs {
 	NL802154_ATTR_SCAN_DONE_REASON,
 	NL802154_ATTR_BEACON_INTERVAL,
 	NL802154_ATTR_MAX_ASSOCIATIONS,
+	NL802154_ATTR_PEER,
 
 	/* add attributes here, update the policy in nl802154.c */
 
@@ -389,8 +391,6 @@ enum nl802154_supported_bool_states {
 	NL802154_SUPPORTED_BOOL_MAX = __NL802154_SUPPORTED_BOOL_AFTER_LAST - 1
 };
 
-#ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
-
 enum nl802154_dev_addr_modes {
 	NL802154_DEV_ADDR_NONE,
 	__NL802154_DEV_ADDR_INVALID,
@@ -410,12 +410,26 @@ enum nl802154_dev_addr_attrs {
 	NL802154_DEV_ADDR_ATTR_SHORT,
 	NL802154_DEV_ADDR_ATTR_EXTENDED,
 	NL802154_DEV_ADDR_ATTR_PAD,
+	NL802154_DEV_ADDR_ATTR_PEER_TYPE,
 
 	/* keep last */
 	__NL802154_DEV_ADDR_ATTR_AFTER_LAST,
 	NL802154_DEV_ADDR_ATTR_MAX = __NL802154_DEV_ADDR_ATTR_AFTER_LAST - 1
 };
 
+enum nl802154_peer_type {
+	NL802154_PEER_TYPE_UNSPEC,
+
+	NL802154_PEER_TYPE_PARENT,
+	NL802154_PEER_TYPE_CHILD,
+
+	/* keep last */
+	__NL802154_PEER_TYPE_AFTER_LAST,
+	NL802154_PEER_TYPE_MAX = __NL802154_PEER_TYPE_AFTER_LAST - 1
+};
+
+#ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
+
 enum nl802154_key_id_modes {
 	NL802154_KEY_ID_MODE_IMPLICIT,
 	NL802154_KEY_ID_MODE_INDEX,

net/ieee802154/nl802154.c

@@ -235,6 +235,7 @@ static const struct nla_policy nl802154_policy[NL802154_ATTR_MAX+1] = {
 	[NL802154_ATTR_BEACON_INTERVAL] =
 		NLA_POLICY_MAX(NLA_U8, IEEE802154_ACTIVE_SCAN_DURATION),
 	[NL802154_ATTR_MAX_ASSOCIATIONS] = { .type = NLA_U32 },
+	[NL802154_ATTR_PEER] = { .type = NLA_NESTED },
 
 #ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
 	[NL802154_ATTR_SEC_ENABLED] = { .type = NLA_U8, },
@@ -249,7 +250,6 @@ static const struct nla_policy nl802154_policy[NL802154_ATTR_MAX+1] = {
 #endif /* CONFIG_IEEE802154_NL802154_EXPERIMENTAL */
 };
 
-#ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
 static int
 nl802154_prepare_wpan_dev_dump(struct sk_buff *skb,
 			       struct netlink_callback *cb,
@@ -308,7 +308,6 @@ nl802154_finish_wpan_dev_dump(struct cfg802154_registered_device *rdev)
 {
 	rtnl_unlock();
 }
-#endif /* CONFIG_IEEE802154_NL802154_EXPERIMENTAL */
 
 /* message building helper */
 static inline void *nl802154hdr_put(struct sk_buff *skb, u32 portid, u32 seq,
@@ -1717,6 +1716,101 @@ static int nl802154_set_max_associations(struct sk_buff *skb, struct genl_info *
 	return 0;
 }
 
+static int nl802154_send_peer_info(struct sk_buff *msg,
+				   struct netlink_callback *cb,
+				   u32 seq, int flags,
+				   struct cfg802154_registered_device *rdev,
+				   struct wpan_dev *wpan_dev,
+				   struct ieee802154_pan_device *peer,
+				   enum nl802154_peer_type type)
+{
+	struct nlattr *nla;
+	void *hdr;
+
+	ASSERT_RTNL();
+
+	hdr = nl802154hdr_put(msg, NETLINK_CB(cb->skb).portid, seq, flags,
+			      NL802154_CMD_LIST_ASSOCIATIONS);
+	if (!hdr)
+		return -ENOBUFS;
+
+	genl_dump_check_consistent(cb, hdr);
+
+	nla = nla_nest_start_noflag(msg, NL802154_ATTR_PEER);
+	if (!nla)
+		goto nla_put_failure;
+
+	if (nla_put_u8(msg, NL802154_DEV_ADDR_ATTR_PEER_TYPE, type))
+		goto nla_put_failure;
+
+	if (nla_put_u8(msg, NL802154_DEV_ADDR_ATTR_MODE, peer->mode))
+		goto nla_put_failure;
+
+	if (nla_put(msg, NL802154_DEV_ADDR_ATTR_SHORT,
+		    IEEE802154_SHORT_ADDR_LEN, &peer->short_addr))
+		goto nla_put_failure;
+
+	if (nla_put(msg, NL802154_DEV_ADDR_ATTR_EXTENDED,
+		    IEEE802154_EXTENDED_ADDR_LEN, &peer->extended_addr))
+		goto nla_put_failure;
+
+	nla_nest_end(msg, nla);
+
+	genlmsg_end(msg, hdr);
+
+	return 0;
+
+ nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	return -EMSGSIZE;
+}
+
+static int nl802154_list_associations(struct sk_buff *skb,
+				      struct netlink_callback *cb)
+{
+	struct cfg802154_registered_device *rdev;
+	struct ieee802154_pan_device *child;
+	struct wpan_dev *wpan_dev;
+	int err;
+
+	err = nl802154_prepare_wpan_dev_dump(skb, cb, &rdev, &wpan_dev);
+	if (err)
+		return err;
+
+	mutex_lock(&wpan_dev->association_lock);
+
+	if (cb->args[2])
+		goto out;
+
+	if (wpan_dev->parent) {
+		err = nl802154_send_peer_info(skb, cb, cb->nlh->nlmsg_seq,
+					      NLM_F_MULTI, rdev, wpan_dev,
+					      wpan_dev->parent,
+					      NL802154_PEER_TYPE_PARENT);
+		if (err < 0)
+			goto out_err;
+	}
+
+	list_for_each_entry(child, &wpan_dev->children, node) {
+		err = nl802154_send_peer_info(skb, cb, cb->nlh->nlmsg_seq,
+					      NLM_F_MULTI, rdev, wpan_dev,
+					      child,
+					      NL802154_PEER_TYPE_CHILD);
+		if (err < 0)
+			goto out_err;
+	}
+
+	cb->args[2] = 1;
+out:
+	err = skb->len;
+out_err:
+	mutex_unlock(&wpan_dev->association_lock);
+
+	nl802154_finish_wpan_dev_dump(rdev);
+
+	return err;
+}
+
 #ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
 static const struct nla_policy nl802154_dev_addr_policy[NL802154_DEV_ADDR_ATTR_MAX + 1] = {
 	[NL802154_DEV_ADDR_ATTR_PAN_ID] = { .type = NLA_U16 },
@@ -2861,6 +2955,11 @@ static const struct genl_ops nl802154_ops[] = {
 		.internal_flags = NL802154_FLAG_NEED_NETDEV |
 				  NL802154_FLAG_NEED_RTNL,
 	},
+	{
+		.cmd = NL802154_CMD_LIST_ASSOCIATIONS,
+		.dumpit = nl802154_list_associations,
+		/* can be retrieved by unprivileged users */
+	},
 #ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
 	{
 		.cmd = NL802154_CMD_SET_SEC_PARAMS,