mptcp: netlink: Add MPTCP_PM_CMD_REMOVE

This change adds a MPTCP netlink command for issuing a
REMOVE_ADDR signal for an address over the chosen MPTCP
connection from a userspace path manager.

The command requires the following parameters: {token, loc_id}.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Kishen Maloor <kishen.maloor@intel.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/mptcp.h

@@ -56,6 +56,7 @@ enum {
 	MPTCP_PM_ATTR_RCV_ADD_ADDRS,			/* u32 */
 	MPTCP_PM_ATTR_SUBFLOWS,				/* u32 */
 	MPTCP_PM_ATTR_TOKEN,				/* u32 */
+	MPTCP_PM_ATTR_LOC_ID,				/* u8 */
 
 	__MPTCP_PM_ATTR_MAX
 };
@@ -95,6 +96,7 @@ enum {
 	MPTCP_PM_CMD_GET_LIMITS,
 	MPTCP_PM_CMD_SET_FLAGS,
 	MPTCP_PM_CMD_ANNOUNCE,
+	MPTCP_PM_CMD_REMOVE,
 
 	__MPTCP_PM_CMD_AFTER_LAST
 };

net/mptcp/pm_netlink.c

@@ -1095,6 +1095,7 @@ static const struct nla_policy mptcp_pm_policy[MPTCP_PM_ATTR_MAX + 1] = {
 	[MPTCP_PM_ATTR_RCV_ADD_ADDRS]	= { .type	= NLA_U32,	},
 	[MPTCP_PM_ATTR_SUBFLOWS]	= { .type	= NLA_U32,	},
 	[MPTCP_PM_ATTR_TOKEN]		= { .type	= NLA_U32,	},
+	[MPTCP_PM_ATTR_LOC_ID]		= { .type	= NLA_U8,	},
 };
 
 void mptcp_pm_nl_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk)
@@ -1504,7 +1505,7 @@ static int mptcp_nl_cmd_del_addr(struct sk_buff *skb, struct genl_info *info)
 	return ret;
 }
 
-static void mptcp_pm_remove_addrs_and_subflows(struct mptcp_sock *msk,
+void mptcp_pm_remove_addrs_and_subflows(struct mptcp_sock *msk,
 					struct list_head *rm_list)
 {
 	struct mptcp_rm_list alist = { .nr = 0 }, slist = { .nr = 0 };
@@ -2204,6 +2205,11 @@ static const struct genl_small_ops mptcp_pm_ops[] = {
 		.doit   = mptcp_nl_cmd_announce,
 		.flags  = GENL_ADMIN_PERM,
 	},
+	{
+		.cmd    = MPTCP_PM_CMD_REMOVE,
+		.doit   = mptcp_nl_cmd_remove,
+		.flags  = GENL_ADMIN_PERM,
+	},
 };
 
 static struct genl_family mptcp_genl_family __ro_after_init = {

net/mptcp/pm_userspace.c

@@ -180,3 +180,65 @@ int mptcp_nl_cmd_announce(struct sk_buff *skb, struct genl_info *info)
 	sock_put((struct sock *)msk);
 	return err;
 }
+
+int mptcp_nl_cmd_remove(struct sk_buff *skb, struct genl_info *info)
+{
+	struct nlattr *token = info->attrs[MPTCP_PM_ATTR_TOKEN];
+	struct nlattr *id = info->attrs[MPTCP_PM_ATTR_LOC_ID];
+	struct mptcp_pm_addr_entry *match = NULL;
+	struct mptcp_pm_addr_entry *entry;
+	struct mptcp_sock *msk;
+	LIST_HEAD(free_list);
+	int err = -EINVAL;
+	u32 token_val;
+	u8 id_val;
+
+	if (!id || !token) {
+		GENL_SET_ERR_MSG(info, "missing required inputs");
+		return err;
+	}
+
+	id_val = nla_get_u8(id);
+	token_val = nla_get_u32(token);
+
+	msk = mptcp_token_get_sock(sock_net(skb->sk), token_val);
+	if (!msk) {
+		NL_SET_ERR_MSG_ATTR(info->extack, token, "invalid token");
+		return err;
+	}
+
+	if (!mptcp_pm_is_userspace(msk)) {
+		GENL_SET_ERR_MSG(info, "invalid request; userspace PM not selected");
+		goto remove_err;
+	}
+
+	lock_sock((struct sock *)msk);
+
+	list_for_each_entry(entry, &msk->pm.userspace_pm_local_addr_list, list) {
+		if (entry->addr.id == id_val) {
+			match = entry;
+			break;
+		}
+	}
+
+	if (!match) {
+		GENL_SET_ERR_MSG(info, "address with specified id not found");
+		release_sock((struct sock *)msk);
+		goto remove_err;
+	}
+
+	list_move(&match->list, &free_list);
+
+	mptcp_pm_remove_addrs_and_subflows(msk, &free_list);
+
+	release_sock((struct sock *)msk);
+
+	list_for_each_entry_safe(match, entry, &free_list, list) {
+		sock_kfree_s((struct sock *)msk, match, sizeof(*match));
+	}
+
+	err = 0;
+ remove_err:
+	sock_put((struct sock *)msk);
+	return err;
+}

net/mptcp/protocol.h

@@ -801,10 +801,14 @@ int mptcp_pm_announce_addr(struct mptcp_sock *msk,
 			   bool echo);
 int mptcp_pm_remove_addr(struct mptcp_sock *msk, const struct mptcp_rm_list *rm_list);
 int mptcp_pm_remove_subflow(struct mptcp_sock *msk, const struct mptcp_rm_list *rm_list);
+void mptcp_pm_remove_addrs_and_subflows(struct mptcp_sock *msk,
+					struct list_head *rm_list);
+
 int mptcp_userspace_pm_append_new_local_addr(struct mptcp_sock *msk,
 					     struct mptcp_pm_addr_entry *entry);
 void mptcp_free_local_addr_list(struct mptcp_sock *msk);
 int mptcp_nl_cmd_announce(struct sk_buff *skb, struct genl_info *info);
+int mptcp_nl_cmd_remove(struct sk_buff *skb, struct genl_info *info);
 
 void mptcp_event(enum mptcp_event_type type, const struct mptcp_sock *msk,
 		 const struct sock *ssk, gfp_t gfp);