mptcp: netlink: allow userspace-driven subflow establishment

This allows userspace to tell kernel to add a new subflow to an existing
mptcp connection.

Userspace provides the token to identify the mptcp-level connection
that needs a change in active subflows and the local and remote
addresses of the new or the to-be-removed subflow.

MPTCP_PM_CMD_SUBFLOW_CREATE requires the following parameters:
{ token, { loc_id, family, loc_addr4 | loc_addr6 }, { family, rem_addr4 |
rem_addr6, rem_port }

MPTCP_PM_CMD_SUBFLOW_DESTROY requires the following parameters:
{ token, { family, loc_addr4 | loc_addr6, loc_port }, { family, rem_addr4 |
rem_addr6, rem_port }

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

1 files changed, 185 insertions, 0 deletions

diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c
index 3a42c9e66126..f56378e4f597 100644
--- a/net/mptcp/pm_userspace.c
+++ b/net/mptcp/pm_userspace.c
@@ -242,3 +242,188 @@ int mptcp_nl_cmd_remove(struct sk_buff *skb, struct genl_info *info)
 	sock_put((struct sock *)msk);
 	return err;
 }
+
+int mptcp_nl_cmd_sf_create(struct sk_buff *skb, struct genl_info *info)
+{
+	struct nlattr *raddr = info->attrs[MPTCP_PM_ATTR_ADDR_REMOTE];
+	struct nlattr *token = info->attrs[MPTCP_PM_ATTR_TOKEN];
+	struct nlattr *laddr = info->attrs[MPTCP_PM_ATTR_ADDR];
+	struct mptcp_addr_info addr_r;
+	struct mptcp_addr_info addr_l;
+	struct mptcp_sock *msk;
+	int err = -EINVAL;
+	struct sock *sk;
+	u32 token_val;
+
+	if (!laddr || !raddr || !token) {
+		GENL_SET_ERR_MSG(info, "missing required inputs");
+		return err;
+	}
+
+	token_val = nla_get_u32(token);
+
+	msk = mptcp_token_get_sock(genl_info_net(info), 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 create_err;
+	}
+
+	err = mptcp_pm_parse_addr(laddr, info, &addr_l);
+	if (err < 0) {
+		NL_SET_ERR_MSG_ATTR(info->extack, laddr, "error parsing local addr");
+		goto create_err;
+	}
+
+	if (addr_l.id == 0) {
+		NL_SET_ERR_MSG_ATTR(info->extack, laddr, "missing local addr id");
+		goto create_err;
+	}
+
+	err = mptcp_pm_parse_addr(raddr, info, &addr_r);
+	if (err < 0) {
+		NL_SET_ERR_MSG_ATTR(info->extack, raddr, "error parsing remote addr");
+		goto create_err;
+	}
+
+	sk = &msk->sk.icsk_inet.sk;
+	lock_sock(sk);
+
+	err = __mptcp_subflow_connect(sk, &addr_l, &addr_r);
+
+	release_sock(sk);
+
+ create_err:
+	sock_put((struct sock *)msk);
+	return err;
+}
+
+static struct sock *mptcp_nl_find_ssk(struct mptcp_sock *msk,
+				      const struct mptcp_addr_info *local,
+				      const struct mptcp_addr_info *remote)
+{
+	struct sock *sk = &msk->sk.icsk_inet.sk;
+	struct mptcp_subflow_context *subflow;
+	struct sock *found = NULL;
+
+	if (local->family != remote->family)
+		return NULL;
+
+	lock_sock(sk);
+
+	mptcp_for_each_subflow(msk, subflow) {
+		const struct inet_sock *issk;
+		struct sock *ssk;
+
+		ssk = mptcp_subflow_tcp_sock(subflow);
+
+		if (local->family != ssk->sk_family)
+			continue;
+
+		issk = inet_sk(ssk);
+
+		switch (ssk->sk_family) {
+		case AF_INET:
+			if (issk->inet_saddr != local->addr.s_addr ||
+			    issk->inet_daddr != remote->addr.s_addr)
+				continue;
+			break;
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+		case AF_INET6: {
+			const struct ipv6_pinfo *pinfo = inet6_sk(ssk);
+
+			if (!ipv6_addr_equal(&local->addr6, &pinfo->saddr) ||
+			    !ipv6_addr_equal(&remote->addr6, &ssk->sk_v6_daddr))
+				continue;
+			break;
+		}
+#endif
+		default:
+			continue;
+		}
+
+		if (issk->inet_sport == local->port &&
+		    issk->inet_dport == remote->port) {
+			found = ssk;
+			goto found;
+		}
+	}
+
+found:
+	release_sock(sk);
+
+	return found;
+}
+
+int mptcp_nl_cmd_sf_destroy(struct sk_buff *skb, struct genl_info *info)
+{
+	struct nlattr *raddr = info->attrs[MPTCP_PM_ATTR_ADDR_REMOTE];
+	struct nlattr *token = info->attrs[MPTCP_PM_ATTR_TOKEN];
+	struct nlattr *laddr = info->attrs[MPTCP_PM_ATTR_ADDR];
+	struct mptcp_addr_info addr_l;
+	struct mptcp_addr_info addr_r;
+	struct mptcp_sock *msk;
+	struct sock *sk, *ssk;
+	int err = -EINVAL;
+	u32 token_val;
+
+	if (!laddr || !raddr || !token) {
+		GENL_SET_ERR_MSG(info, "missing required inputs");
+		return err;
+	}
+
+	token_val = nla_get_u32(token);
+
+	msk = mptcp_token_get_sock(genl_info_net(info), 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 destroy_err;
+	}
+
+	err = mptcp_pm_parse_addr(laddr, info, &addr_l);
+	if (err < 0) {
+		NL_SET_ERR_MSG_ATTR(info->extack, laddr, "error parsing local addr");
+		goto destroy_err;
+	}
+
+	err = mptcp_pm_parse_addr(raddr, info, &addr_r);
+	if (err < 0) {
+		NL_SET_ERR_MSG_ATTR(info->extack, raddr, "error parsing remote addr");
+		goto destroy_err;
+	}
+
+	if (addr_l.family != addr_r.family) {
+		GENL_SET_ERR_MSG(info, "address families do not match");
+		goto destroy_err;
+	}
+
+	if (!addr_l.port || !addr_r.port) {
+		GENL_SET_ERR_MSG(info, "missing local or remote port");
+		goto destroy_err;
+	}
+
+	sk = &msk->sk.icsk_inet.sk;
+	ssk = mptcp_nl_find_ssk(msk, &addr_l, &addr_r);
+	if (ssk) {
+		struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+
+		mptcp_subflow_shutdown(sk, ssk, RCV_SHUTDOWN | SEND_SHUTDOWN);
+		mptcp_close_ssk(sk, ssk, subflow);
+		err = 0;
+	} else {
+		err = -ESRCH;
+	}
+
+ destroy_err:
+	sock_put((struct sock *)msk);
+	return err;
+}