Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1486 insertions, 0 deletions

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
new file mode 100644
index 0000000000..116e300823
--- /dev/null
+++ b/net/mptcp/sockopt.c
@@ -0,0 +1,1486 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Multipath TCP
+ *
+ * Copyright (c) 2021, Red Hat.
+ */
+
+#define pr_fmt(fmt) "MPTCP: " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <net/sock.h>
+#include <net/protocol.h>
+#include <net/tcp.h>
+#include <net/mptcp.h>
+#include "protocol.h"
+
+#define MIN_INFO_OPTLEN_SIZE		16
+#define MIN_FULL_INFO_OPTLEN_SIZE	40
+
+static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk)
+{
+	msk_owned_by_me(msk);
+
+	if (likely(!__mptcp_check_fallback(msk)))
+		return NULL;
+
+	return msk->first;
+}
+
+static u32 sockopt_seq_reset(const struct sock *sk)
+{
+	sock_owned_by_me(sk);
+
+	/* Highbits contain state.  Allows to distinguish sockopt_seq
+	 * of listener and established:
+	 * s0 = new_listener()
+	 * sockopt(s0) - seq is 1
+	 * s1 = accept(s0) - s1 inherits seq 1 if listener sk (s0)
+	 * sockopt(s0) - seq increments to 2 on s0
+	 * sockopt(s1) // seq increments to 2 on s1 (different option)
+	 * new ssk completes join, inherits options from s0 // seq 2
+	 * Needs sync from mptcp join logic, but ssk->seq == msk->seq
+	 *
+	 * Set High order bits to sk_state so ssk->seq == msk->seq test
+	 * will fail.
+	 */
+
+	return (u32)sk->sk_state << 24u;
+}
+
+static void sockopt_seq_inc(struct mptcp_sock *msk)
+{
+	u32 seq = (msk->setsockopt_seq + 1) & 0x00ffffff;
+
+	msk->setsockopt_seq = sockopt_seq_reset((struct sock *)msk) + seq;
+}
+
+static int mptcp_get_int_option(struct mptcp_sock *msk, sockptr_t optval,
+				unsigned int optlen, int *val)
+{
+	if (optlen < sizeof(int))
+		return -EINVAL;
+
+	if (copy_from_sockptr(val, optval, sizeof(*val)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static void mptcp_sol_socket_sync_intval(struct mptcp_sock *msk, int optname, int val)
+{
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+
+	lock_sock(sk);
+	sockopt_seq_inc(msk);
+
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		bool slow = lock_sock_fast(ssk);
+
+		switch (optname) {
+		case SO_DEBUG:
+			sock_valbool_flag(ssk, SOCK_DBG, !!val);
+			break;
+		case SO_KEEPALIVE:
+			if (ssk->sk_prot->keepalive)
+				ssk->sk_prot->keepalive(ssk, !!val);
+			sock_valbool_flag(ssk, SOCK_KEEPOPEN, !!val);
+			break;
+		case SO_PRIORITY:
+			ssk->sk_priority = val;
+			break;
+		case SO_SNDBUF:
+		case SO_SNDBUFFORCE:
+			ssk->sk_userlocks |= SOCK_SNDBUF_LOCK;
+			WRITE_ONCE(ssk->sk_sndbuf, sk->sk_sndbuf);
+			mptcp_subflow_ctx(ssk)->cached_sndbuf = sk->sk_sndbuf;
+			break;
+		case SO_RCVBUF:
+		case SO_RCVBUFFORCE:
+			ssk->sk_userlocks |= SOCK_RCVBUF_LOCK;
+			WRITE_ONCE(ssk->sk_rcvbuf, sk->sk_rcvbuf);
+			break;
+		case SO_MARK:
+			if (READ_ONCE(ssk->sk_mark) != sk->sk_mark) {
+				WRITE_ONCE(ssk->sk_mark, sk->sk_mark);
+				sk_dst_reset(ssk);
+			}
+			break;
+		case SO_INCOMING_CPU:
+			WRITE_ONCE(ssk->sk_incoming_cpu, val);
+			break;
+		}
+
+		subflow->setsockopt_seq = msk->setsockopt_seq;
+		unlock_sock_fast(ssk, slow);
+	}
+
+	release_sock(sk);
+}
+
+static int mptcp_sol_socket_intval(struct mptcp_sock *msk, int optname, int val)
+{
+	sockptr_t optval = KERNEL_SOCKPTR(&val);
+	struct sock *sk = (struct sock *)msk;
+	int ret;
+
+	ret = sock_setsockopt(sk->sk_socket, SOL_SOCKET, optname,
+			      optval, sizeof(val));
+	if (ret)
+		return ret;
+
+	mptcp_sol_socket_sync_intval(msk, optname, val);
+	return 0;
+}
+
+static void mptcp_so_incoming_cpu(struct mptcp_sock *msk, int val)
+{
+	struct sock *sk = (struct sock *)msk;
+
+	WRITE_ONCE(sk->sk_incoming_cpu, val);
+
+	mptcp_sol_socket_sync_intval(msk, SO_INCOMING_CPU, val);
+}
+
+static int mptcp_setsockopt_sol_socket_tstamp(struct mptcp_sock *msk, int optname, int val)
+{
+	sockptr_t optval = KERNEL_SOCKPTR(&val);
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+	int ret;
+
+	ret = sock_setsockopt(sk->sk_socket, SOL_SOCKET, optname,
+			      optval, sizeof(val));
+	if (ret)
+		return ret;
+
+	lock_sock(sk);
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		bool slow = lock_sock_fast(ssk);
+
+		sock_set_timestamp(sk, optname, !!val);
+		unlock_sock_fast(ssk, slow);
+	}
+
+	release_sock(sk);
+	return 0;
+}
+
+static int mptcp_setsockopt_sol_socket_int(struct mptcp_sock *msk, int optname,
+					   sockptr_t optval,
+					   unsigned int optlen)
+{
+	int val, ret;
+
+	ret = mptcp_get_int_option(msk, optval, optlen, &val);
+	if (ret)
+		return ret;
+
+	switch (optname) {
+	case SO_KEEPALIVE:
+		mptcp_sol_socket_sync_intval(msk, optname, val);
+		return 0;
+	case SO_DEBUG:
+	case SO_MARK:
+	case SO_PRIORITY:
+	case SO_SNDBUF:
+	case SO_SNDBUFFORCE:
+	case SO_RCVBUF:
+	case SO_RCVBUFFORCE:
+		return mptcp_sol_socket_intval(msk, optname, val);
+	case SO_INCOMING_CPU:
+		mptcp_so_incoming_cpu(msk, val);
+		return 0;
+	case SO_TIMESTAMP_OLD:
+	case SO_TIMESTAMP_NEW:
+	case SO_TIMESTAMPNS_OLD:
+	case SO_TIMESTAMPNS_NEW:
+		return mptcp_setsockopt_sol_socket_tstamp(msk, optname, val);
+	}
+
+	return -ENOPROTOOPT;
+}
+
+static int mptcp_setsockopt_sol_socket_timestamping(struct mptcp_sock *msk,
+						    int optname,
+						    sockptr_t optval,
+						    unsigned int optlen)
+{
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+	struct so_timestamping timestamping;
+	int ret;
+
+	if (optlen == sizeof(timestamping)) {
+		if (copy_from_sockptr(&timestamping, optval,
+				      sizeof(timestamping)))
+			return -EFAULT;
+	} else if (optlen == sizeof(int)) {
+		memset(&timestamping, 0, sizeof(timestamping));
+
+		if (copy_from_sockptr(&timestamping.flags, optval, sizeof(int)))
+			return -EFAULT;
+	} else {
+		return -EINVAL;
+	}
+
+	ret = sock_setsockopt(sk->sk_socket, SOL_SOCKET, optname,
+			      KERNEL_SOCKPTR(&timestamping),
+			      sizeof(timestamping));
+	if (ret)
+		return ret;
+
+	lock_sock(sk);
+
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		bool slow = lock_sock_fast(ssk);
+
+		sock_set_timestamping(sk, optname, timestamping);
+		unlock_sock_fast(ssk, slow);
+	}
+
+	release_sock(sk);
+
+	return 0;
+}
+
+static int mptcp_setsockopt_sol_socket_linger(struct mptcp_sock *msk, sockptr_t optval,
+					      unsigned int optlen)
+{
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+	struct linger ling;
+	sockptr_t kopt;
+	int ret;
+
+	if (optlen < sizeof(ling))
+		return -EINVAL;
+
+	if (copy_from_sockptr(&ling, optval, sizeof(ling)))
+		return -EFAULT;
+
+	kopt = KERNEL_SOCKPTR(&ling);
+	ret = sock_setsockopt(sk->sk_socket, SOL_SOCKET, SO_LINGER, kopt, sizeof(ling));
+	if (ret)
+		return ret;
+
+	lock_sock(sk);
+	sockopt_seq_inc(msk);
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		bool slow = lock_sock_fast(ssk);
+
+		if (!ling.l_onoff) {
+			sock_reset_flag(ssk, SOCK_LINGER);
+		} else {
+			ssk->sk_lingertime = sk->sk_lingertime;
+			sock_set_flag(ssk, SOCK_LINGER);
+		}
+
+		subflow->setsockopt_seq = msk->setsockopt_seq;
+		unlock_sock_fast(ssk, slow);
+	}
+
+	release_sock(sk);
+	return 0;
+}
+
+static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname,
+				       sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = (struct sock *)msk;
+	struct sock *ssk;
+	int ret;
+
+	switch (optname) {
+	case SO_REUSEPORT:
+	case SO_REUSEADDR:
+	case SO_BINDTODEVICE:
+	case SO_BINDTOIFINDEX:
+		lock_sock(sk);
+		ssk = __mptcp_nmpc_sk(msk);
+		if (IS_ERR(ssk)) {
+			release_sock(sk);
+			return PTR_ERR(ssk);
+		}
+
+		ret = sk_setsockopt(ssk, SOL_SOCKET, optname, optval, optlen);
+		if (ret == 0) {
+			if (optname == SO_REUSEPORT)
+				sk->sk_reuseport = ssk->sk_reuseport;
+			else if (optname == SO_REUSEADDR)
+				sk->sk_reuse = ssk->sk_reuse;
+			else if (optname == SO_BINDTODEVICE)
+				sk->sk_bound_dev_if = ssk->sk_bound_dev_if;
+			else if (optname == SO_BINDTOIFINDEX)
+				sk->sk_bound_dev_if = ssk->sk_bound_dev_if;
+		}
+		release_sock(sk);
+		return ret;
+	case SO_KEEPALIVE:
+	case SO_PRIORITY:
+	case SO_SNDBUF:
+	case SO_SNDBUFFORCE:
+	case SO_RCVBUF:
+	case SO_RCVBUFFORCE:
+	case SO_MARK:
+	case SO_INCOMING_CPU:
+	case SO_DEBUG:
+	case SO_TIMESTAMP_OLD:
+	case SO_TIMESTAMP_NEW:
+	case SO_TIMESTAMPNS_OLD:
+	case SO_TIMESTAMPNS_NEW:
+		return mptcp_setsockopt_sol_socket_int(msk, optname, optval,
+						       optlen);
+	case SO_TIMESTAMPING_OLD:
+	case SO_TIMESTAMPING_NEW:
+		return mptcp_setsockopt_sol_socket_timestamping(msk, optname,
+								optval, optlen);
+	case SO_LINGER:
+		return mptcp_setsockopt_sol_socket_linger(msk, optval, optlen);
+	case SO_RCVLOWAT:
+	case SO_RCVTIMEO_OLD:
+	case SO_RCVTIMEO_NEW:
+	case SO_SNDTIMEO_OLD:
+	case SO_SNDTIMEO_NEW:
+	case SO_BUSY_POLL:
+	case SO_PREFER_BUSY_POLL:
+	case SO_BUSY_POLL_BUDGET:
+		/* No need to copy: only relevant for msk */
+		return sock_setsockopt(sk->sk_socket, SOL_SOCKET, optname, optval, optlen);
+	case SO_NO_CHECK:
+	case SO_DONTROUTE:
+	case SO_BROADCAST:
+	case SO_BSDCOMPAT:
+	case SO_PASSCRED:
+	case SO_PASSPIDFD:
+	case SO_PASSSEC:
+	case SO_RXQ_OVFL:
+	case SO_WIFI_STATUS:
+	case SO_NOFCS:
+	case SO_SELECT_ERR_QUEUE:
+		return 0;
+	}
+
+	/* SO_OOBINLINE is not supported, let's avoid the related mess
+	 * SO_ATTACH_FILTER, SO_ATTACH_BPF, SO_ATTACH_REUSEPORT_CBPF,
+	 * SO_DETACH_REUSEPORT_BPF, SO_DETACH_FILTER, SO_LOCK_FILTER,
+	 * we must be careful with subflows
+	 *
+	 * SO_ATTACH_REUSEPORT_EBPF is not supported, at it checks
+	 * explicitly the sk_protocol field
+	 *
+	 * SO_PEEK_OFF is unsupported, as it is for plain TCP
+	 * SO_MAX_PACING_RATE is unsupported, we must be careful with subflows
+	 * SO_CNX_ADVICE is currently unsupported, could possibly be relevant,
+	 * but likely needs careful design
+	 *
+	 * SO_ZEROCOPY is currently unsupported, TODO in sndmsg
+	 * SO_TXTIME is currently unsupported
+	 */
+
+	return -EOPNOTSUPP;
+}
+
+static int mptcp_setsockopt_v6(struct mptcp_sock *msk, int optname,
+			       sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = (struct sock *)msk;
+	int ret = -EOPNOTSUPP;
+	struct sock *ssk;
+
+	switch (optname) {
+	case IPV6_V6ONLY:
+	case IPV6_TRANSPARENT:
+	case IPV6_FREEBIND:
+		lock_sock(sk);
+		ssk = __mptcp_nmpc_sk(msk);
+		if (IS_ERR(ssk)) {
+			release_sock(sk);
+			return PTR_ERR(ssk);
+		}
+
+		ret = tcp_setsockopt(ssk, SOL_IPV6, optname, optval, optlen);
+		if (ret != 0) {
+			release_sock(sk);
+			return ret;
+		}
+
+		sockopt_seq_inc(msk);
+
+		switch (optname) {
+		case IPV6_V6ONLY:
+			sk->sk_ipv6only = ssk->sk_ipv6only;
+			break;
+		case IPV6_TRANSPARENT:
+			inet_assign_bit(TRANSPARENT, sk,
+					inet_test_bit(TRANSPARENT, ssk));
+			break;
+		case IPV6_FREEBIND:
+			inet_assign_bit(FREEBIND, sk,
+					inet_test_bit(FREEBIND, ssk));
+			break;
+		}
+
+		release_sock(sk);
+		break;
+	}
+
+	return ret;
+}
+
+static bool mptcp_supported_sockopt(int level, int optname)
+{
+	if (level == SOL_IP) {
+		switch (optname) {
+		/* should work fine */
+		case IP_FREEBIND:
+		case IP_TRANSPARENT:
+
+		/* the following are control cmsg related */
+		case IP_PKTINFO:
+		case IP_RECVTTL:
+		case IP_RECVTOS:
+		case IP_RECVOPTS:
+		case IP_RETOPTS:
+		case IP_PASSSEC:
+		case IP_RECVORIGDSTADDR:
+		case IP_CHECKSUM:
+		case IP_RECVFRAGSIZE:
+
+		/* common stuff that need some love */
+		case IP_TOS:
+		case IP_TTL:
+		case IP_BIND_ADDRESS_NO_PORT:
+		case IP_MTU_DISCOVER:
+		case IP_RECVERR:
+
+		/* possibly less common may deserve some love */
+		case IP_MINTTL:
+
+		/* the following is apparently a no-op for plain TCP */
+		case IP_RECVERR_RFC4884:
+			return true;
+		}
+
+		/* IP_OPTIONS is not supported, needs subflow care */
+		/* IP_HDRINCL, IP_NODEFRAG are not supported, RAW specific */
+		/* IP_MULTICAST_TTL, IP_MULTICAST_LOOP, IP_UNICAST_IF,
+		 * IP_ADD_MEMBERSHIP, IP_ADD_SOURCE_MEMBERSHIP, IP_DROP_MEMBERSHIP,
+		 * IP_DROP_SOURCE_MEMBERSHIP, IP_BLOCK_SOURCE, IP_UNBLOCK_SOURCE,
+		 * MCAST_JOIN_GROUP, MCAST_LEAVE_GROUP MCAST_JOIN_SOURCE_GROUP,
+		 * MCAST_LEAVE_SOURCE_GROUP, MCAST_BLOCK_SOURCE, MCAST_UNBLOCK_SOURCE,
+		 * MCAST_MSFILTER, IP_MULTICAST_ALL are not supported, better not deal
+		 * with mcast stuff
+		 */
+		/* IP_IPSEC_POLICY, IP_XFRM_POLICY are nut supported, unrelated here */
+		return false;
+	}
+	if (level == SOL_IPV6) {
+		switch (optname) {
+		case IPV6_V6ONLY:
+
+		/* the following are control cmsg related */
+		case IPV6_RECVPKTINFO:
+		case IPV6_2292PKTINFO:
+		case IPV6_RECVHOPLIMIT:
+		case IPV6_2292HOPLIMIT:
+		case IPV6_RECVRTHDR:
+		case IPV6_2292RTHDR:
+		case IPV6_RECVHOPOPTS:
+		case IPV6_2292HOPOPTS:
+		case IPV6_RECVDSTOPTS:
+		case IPV6_2292DSTOPTS:
+		case IPV6_RECVTCLASS:
+		case IPV6_FLOWINFO:
+		case IPV6_RECVPATHMTU:
+		case IPV6_RECVORIGDSTADDR:
+		case IPV6_RECVFRAGSIZE:
+
+		/* the following ones need some love but are quite common */
+		case IPV6_TCLASS:
+		case IPV6_TRANSPARENT:
+		case IPV6_FREEBIND:
+		case IPV6_PKTINFO:
+		case IPV6_2292PKTOPTIONS:
+		case IPV6_UNICAST_HOPS:
+		case IPV6_MTU_DISCOVER:
+		case IPV6_MTU:
+		case IPV6_RECVERR:
+		case IPV6_FLOWINFO_SEND:
+		case IPV6_FLOWLABEL_MGR:
+		case IPV6_MINHOPCOUNT:
+		case IPV6_DONTFRAG:
+		case IPV6_AUTOFLOWLABEL:
+
+		/* the following one is a no-op for plain TCP */
+		case IPV6_RECVERR_RFC4884:
+			return true;
+		}
+
+		/* IPV6_HOPOPTS, IPV6_RTHDRDSTOPTS, IPV6_RTHDR, IPV6_DSTOPTS are
+		 * not supported
+		 */
+		/* IPV6_MULTICAST_HOPS, IPV6_MULTICAST_LOOP, IPV6_UNICAST_IF,
+		 * IPV6_MULTICAST_IF, IPV6_ADDRFORM,
+		 * IPV6_ADD_MEMBERSHIP, IPV6_DROP_MEMBERSHIP, IPV6_JOIN_ANYCAST,
+		 * IPV6_LEAVE_ANYCAST, IPV6_MULTICAST_ALL, MCAST_JOIN_GROUP, MCAST_LEAVE_GROUP,
+		 * MCAST_JOIN_SOURCE_GROUP, MCAST_LEAVE_SOURCE_GROUP,
+		 * MCAST_BLOCK_SOURCE, MCAST_UNBLOCK_SOURCE, MCAST_MSFILTER
+		 * are not supported better not deal with mcast
+		 */
+		/* IPV6_ROUTER_ALERT, IPV6_ROUTER_ALERT_ISOLATE are not supported, since are evil */
+
+		/* IPV6_IPSEC_POLICY, IPV6_XFRM_POLICY are not supported */
+		/* IPV6_ADDR_PREFERENCES is not supported, we must be careful with subflows */
+		return false;
+	}
+	if (level == SOL_TCP) {
+		switch (optname) {
+		/* the following are no-op or should work just fine */
+		case TCP_THIN_DUPACK:
+		case TCP_DEFER_ACCEPT:
+
+		/* the following need some love */
+		case TCP_MAXSEG:
+		case TCP_NODELAY:
+		case TCP_THIN_LINEAR_TIMEOUTS:
+		case TCP_CONGESTION:
+		case TCP_CORK:
+		case TCP_KEEPIDLE:
+		case TCP_KEEPINTVL:
+		case TCP_KEEPCNT:
+		case TCP_SYNCNT:
+		case TCP_SAVE_SYN:
+		case TCP_LINGER2:
+		case TCP_WINDOW_CLAMP:
+		case TCP_QUICKACK:
+		case TCP_USER_TIMEOUT:
+		case TCP_TIMESTAMP:
+		case TCP_NOTSENT_LOWAT:
+		case TCP_TX_DELAY:
+		case TCP_INQ:
+		case TCP_FASTOPEN:
+		case TCP_FASTOPEN_CONNECT:
+		case TCP_FASTOPEN_KEY:
+		case TCP_FASTOPEN_NO_COOKIE:
+			return true;
+		}
+
+		/* TCP_MD5SIG, TCP_MD5SIG_EXT are not supported, MD5 is not compatible with MPTCP */
+
+		/* TCP_REPAIR, TCP_REPAIR_QUEUE, TCP_QUEUE_SEQ, TCP_REPAIR_OPTIONS,
+		 * TCP_REPAIR_WINDOW are not supported, better avoid this mess
+		 */
+	}
+	return false;
+}
+
+static int mptcp_setsockopt_sol_tcp_congestion(struct mptcp_sock *msk, sockptr_t optval,
+					       unsigned int optlen)
+{
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+	char name[TCP_CA_NAME_MAX];
+	bool cap_net_admin;
+	int ret;
+
+	if (optlen < 1)
+		return -EINVAL;
+
+	ret = strncpy_from_sockptr(name, optval,
+				   min_t(long, TCP_CA_NAME_MAX - 1, optlen));
+	if (ret < 0)
+		return -EFAULT;
+
+	name[ret] = 0;
+
+	cap_net_admin = ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN);
+
+	ret = 0;
+	lock_sock(sk);
+	sockopt_seq_inc(msk);
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		int err;
+
+		lock_sock(ssk);
+		err = tcp_set_congestion_control(ssk, name, true, cap_net_admin);
+		if (err < 0 && ret == 0)
+			ret = err;
+		subflow->setsockopt_seq = msk->setsockopt_seq;
+		release_sock(ssk);
+	}
+
+	if (ret == 0)
+		strcpy(msk->ca_name, name);
+
+	release_sock(sk);
+	return ret;
+}
+
+static int mptcp_setsockopt_sol_tcp_cork(struct mptcp_sock *msk, sockptr_t optval,
+					 unsigned int optlen)
+{
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+	int val;
+
+	if (optlen < sizeof(int))
+		return -EINVAL;
+
+	if (copy_from_sockptr(&val, optval, sizeof(val)))
+		return -EFAULT;
+
+	lock_sock(sk);
+	sockopt_seq_inc(msk);
+	msk->cork = !!val;
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+
+		lock_sock(ssk);
+		__tcp_sock_set_cork(ssk, !!val);
+		release_sock(ssk);
+	}
+	if (!val)
+		mptcp_check_and_set_pending(sk);
+	release_sock(sk);
+
+	return 0;
+}
+
+static int mptcp_setsockopt_sol_tcp_nodelay(struct mptcp_sock *msk, sockptr_t optval,
+					    unsigned int optlen)
+{
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+	int val;
+
+	if (optlen < sizeof(int))
+		return -EINVAL;
+
+	if (copy_from_sockptr(&val, optval, sizeof(val)))
+		return -EFAULT;
+
+	lock_sock(sk);
+	sockopt_seq_inc(msk);
+	msk->nodelay = !!val;
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+
+		lock_sock(ssk);
+		__tcp_sock_set_nodelay(ssk, !!val);
+		release_sock(ssk);
+	}
+	if (val)
+		mptcp_check_and_set_pending(sk);
+	release_sock(sk);
+
+	return 0;
+}
+
+static int mptcp_setsockopt_sol_ip_set_transparent(struct mptcp_sock *msk, int optname,
+						   sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = (struct sock *)msk;
+	struct sock *ssk;
+	int err;
+
+	err = ip_setsockopt(sk, SOL_IP, optname, optval, optlen);
+	if (err != 0)
+		return err;
+
+	lock_sock(sk);
+
+	ssk = __mptcp_nmpc_sk(msk);
+	if (IS_ERR(ssk)) {
+		release_sock(sk);
+		return PTR_ERR(ssk);
+	}
+
+	switch (optname) {
+	case IP_FREEBIND:
+		inet_assign_bit(FREEBIND, ssk, inet_test_bit(FREEBIND, sk));
+		break;
+	case IP_TRANSPARENT:
+		inet_assign_bit(TRANSPARENT, ssk,
+				inet_test_bit(TRANSPARENT, sk));
+		break;
+	default:
+		release_sock(sk);
+		WARN_ON_ONCE(1);
+		return -EOPNOTSUPP;
+	}
+
+	sockopt_seq_inc(msk);
+	release_sock(sk);
+	return 0;
+}
+
+static int mptcp_setsockopt_v4_set_tos(struct mptcp_sock *msk, int optname,
+				       sockptr_t optval, unsigned int optlen)
+{
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+	int err, val;
+
+	err = ip_setsockopt(sk, SOL_IP, optname, optval, optlen);
+
+	if (err != 0)
+		return err;
+
+	lock_sock(sk);
+	sockopt_seq_inc(msk);
+	val = inet_sk(sk)->tos;
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		bool slow;
+
+		slow = lock_sock_fast(ssk);
+		__ip_sock_set_tos(ssk, val);
+		unlock_sock_fast(ssk, slow);
+	}
+	release_sock(sk);
+
+	return 0;
+}
+
+static int mptcp_setsockopt_v4(struct mptcp_sock *msk, int optname,
+			       sockptr_t optval, unsigned int optlen)
+{
+	switch (optname) {
+	case IP_FREEBIND:
+	case IP_TRANSPARENT:
+		return mptcp_setsockopt_sol_ip_set_transparent(msk, optname, optval, optlen);
+	case IP_TOS:
+		return mptcp_setsockopt_v4_set_tos(msk, optname, optval, optlen);
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static int mptcp_setsockopt_first_sf_only(struct mptcp_sock *msk, int level, int optname,
+					  sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = (struct sock *)msk;
+	struct sock *ssk;
+	int ret;
+
+	/* Limit to first subflow, before the connection establishment */
+	lock_sock(sk);
+	ssk = __mptcp_nmpc_sk(msk);
+	if (IS_ERR(ssk)) {
+		ret = PTR_ERR(ssk);
+		goto unlock;
+	}
+
+	ret = tcp_setsockopt(ssk, level, optname, optval, optlen);
+
+unlock:
+	release_sock(sk);
+	return ret;
+}
+
+static int mptcp_setsockopt_sol_tcp(struct mptcp_sock *msk, int optname,
+				    sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = (void *)msk;
+	int ret, val;
+
+	switch (optname) {
+	case TCP_INQ:
+		ret = mptcp_get_int_option(msk, optval, optlen, &val);
+		if (ret)
+			return ret;
+		if (val < 0 || val > 1)
+			return -EINVAL;
+
+		lock_sock(sk);
+		msk->recvmsg_inq = !!val;
+		release_sock(sk);
+		return 0;
+	case TCP_ULP:
+		return -EOPNOTSUPP;
+	case TCP_CONGESTION:
+		return mptcp_setsockopt_sol_tcp_congestion(msk, optval, optlen);
+	case TCP_CORK:
+		return mptcp_setsockopt_sol_tcp_cork(msk, optval, optlen);
+	case TCP_NODELAY:
+		return mptcp_setsockopt_sol_tcp_nodelay(msk, optval, optlen);
+	case TCP_DEFER_ACCEPT:
+		/* See tcp.c: TCP_DEFER_ACCEPT does not fail */
+		mptcp_setsockopt_first_sf_only(msk, SOL_TCP, optname, optval, optlen);
+		return 0;
+	case TCP_FASTOPEN:
+	case TCP_FASTOPEN_CONNECT:
+	case TCP_FASTOPEN_KEY:
+	case TCP_FASTOPEN_NO_COOKIE:
+		return mptcp_setsockopt_first_sf_only(msk, SOL_TCP, optname,
+						      optval, optlen);
+	}
+
+	return -EOPNOTSUPP;
+}
+
+int mptcp_setsockopt(struct sock *sk, int level, int optname,
+		     sockptr_t optval, unsigned int optlen)
+{
+	struct mptcp_sock *msk = mptcp_sk(sk);
+	struct sock *ssk;
+
+	pr_debug("msk=%p", msk);
+
+	if (level == SOL_SOCKET)
+		return mptcp_setsockopt_sol_socket(msk, optname, optval, optlen);
+
+	if (!mptcp_supported_sockopt(level, optname))
+		return -ENOPROTOOPT;
+
+	/* @@ the meaning of setsockopt() when the socket is connected and
+	 * there are multiple subflows is not yet defined. It is up to the
+	 * MPTCP-level socket to configure the subflows until the subflow
+	 * is in TCP fallback, when TCP socket options are passed through
+	 * to the one remaining subflow.
+	 */
+	lock_sock(sk);
+	ssk = __mptcp_tcp_fallback(msk);
+	release_sock(sk);
+	if (ssk)
+		return tcp_setsockopt(ssk, level, optname, optval, optlen);
+
+	if (level == SOL_IP)
+		return mptcp_setsockopt_v4(msk, optname, optval, optlen);
+
+	if (level == SOL_IPV6)
+		return mptcp_setsockopt_v6(msk, optname, optval, optlen);
+
+	if (level == SOL_TCP)
+		return mptcp_setsockopt_sol_tcp(msk, optname, optval, optlen);
+
+	return -EOPNOTSUPP;
+}
+
+static int mptcp_getsockopt_first_sf_only(struct mptcp_sock *msk, int level, int optname,
+					  char __user *optval, int __user *optlen)
+{
+	struct sock *sk = (struct sock *)msk;
+	struct sock *ssk;
+	int ret;
+
+	lock_sock(sk);
+	ssk = msk->first;
+	if (ssk) {
+		ret = tcp_getsockopt(ssk, level, optname, optval, optlen);
+		goto out;
+	}
+
+	ssk = __mptcp_nmpc_sk(msk);
+	if (IS_ERR(ssk)) {
+		ret = PTR_ERR(ssk);
+		goto out;
+	}
+
+	ret = tcp_getsockopt(ssk, level, optname, optval, optlen);
+
+out:
+	release_sock(sk);
+	return ret;
+}
+
+void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info)
+{
+	struct sock *sk = (struct sock *)msk;
+	u32 flags = 0;
+	bool slow;
+
+	memset(info, 0, sizeof(*info));
+
+	info->mptcpi_subflows = READ_ONCE(msk->pm.subflows);
+	info->mptcpi_add_addr_signal = READ_ONCE(msk->pm.add_addr_signaled);
+	info->mptcpi_add_addr_accepted = READ_ONCE(msk->pm.add_addr_accepted);
+	info->mptcpi_local_addr_used = READ_ONCE(msk->pm.local_addr_used);
+
+	if (inet_sk_state_load(sk) == TCP_LISTEN)
+		return;
+
+	/* The following limits only make sense for the in-kernel PM */
+	if (mptcp_pm_is_kernel(msk)) {
+		info->mptcpi_subflows_max =
+			mptcp_pm_get_subflows_max(msk);
+		info->mptcpi_add_addr_signal_max =
+			mptcp_pm_get_add_addr_signal_max(msk);
+		info->mptcpi_add_addr_accepted_max =
+			mptcp_pm_get_add_addr_accept_max(msk);
+		info->mptcpi_local_addr_max =
+			mptcp_pm_get_local_addr_max(msk);
+	}
+
+	if (test_bit(MPTCP_FALLBACK_DONE, &msk->flags))
+		flags |= MPTCP_INFO_FLAG_FALLBACK;
+	if (READ_ONCE(msk->can_ack))
+		flags |= MPTCP_INFO_FLAG_REMOTE_KEY_RECEIVED;
+	info->mptcpi_flags = flags;
+	mptcp_data_lock(sk);
+	info->mptcpi_snd_una = msk->snd_una;
+	info->mptcpi_rcv_nxt = msk->ack_seq;
+	info->mptcpi_bytes_acked = msk->bytes_acked;
+	mptcp_data_unlock(sk);
+
+	slow = lock_sock_fast(sk);
+	info->mptcpi_csum_enabled = msk->csum_enabled;
+	info->mptcpi_token = msk->token;
+	info->mptcpi_write_seq = msk->write_seq;
+	info->mptcpi_retransmits = inet_csk(sk)->icsk_retransmits;
+	info->mptcpi_bytes_sent = msk->bytes_sent;
+	info->mptcpi_bytes_received = msk->bytes_received;
+	info->mptcpi_bytes_retrans = msk->bytes_retrans;
+	unlock_sock_fast(sk, slow);
+}
+EXPORT_SYMBOL_GPL(mptcp_diag_fill_info);
+
+static int mptcp_getsockopt_info(struct mptcp_sock *msk, char __user *optval, int __user *optlen)
+{
+	struct mptcp_info m_info;
+	int len;
+
+	if (get_user(len, optlen))
+		return -EFAULT;
+
+	len = min_t(unsigned int, len, sizeof(struct mptcp_info));
+
+	mptcp_diag_fill_info(msk, &m_info);
+
+	if (put_user(len, optlen))
+		return -EFAULT;
+
+	if (copy_to_user(optval, &m_info, len))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int mptcp_put_subflow_data(struct mptcp_subflow_data *sfd,
+				  char __user *optval,
+				  u32 copied,
+				  int __user *optlen)
+{
+	u32 copylen = min_t(u32, sfd->size_subflow_data, sizeof(*sfd));
+
+	if (copied)
+		copied += sfd->size_subflow_data;
+	else
+		copied = copylen;
+
+	if (put_user(copied, optlen))
+		return -EFAULT;
+
+	if (copy_to_user(optval, sfd, copylen))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int mptcp_get_subflow_data(struct mptcp_subflow_data *sfd,
+				  char __user *optval,
+				  int __user *optlen)
+{
+	int len, copylen;
+
+	if (get_user(len, optlen))
+		return -EFAULT;
+
+	/* if mptcp_subflow_data size is changed, need to adjust
+	 * this function to deal with programs using old version.
+	 */
+	BUILD_BUG_ON(sizeof(*sfd) != MIN_INFO_OPTLEN_SIZE);
+
+	if (len < MIN_INFO_OPTLEN_SIZE)
+		return -EINVAL;
+
+	memset(sfd, 0, sizeof(*sfd));
+
+	copylen = min_t(unsigned int, len, sizeof(*sfd));
+	if (copy_from_user(sfd, optval, copylen))
+		return -EFAULT;
+
+	/* size_subflow_data is u32, but len is signed */
+	if (sfd->size_subflow_data > INT_MAX ||
+	    sfd->size_user > INT_MAX)
+		return -EINVAL;
+
+	if (sfd->size_subflow_data < MIN_INFO_OPTLEN_SIZE ||
+	    sfd->size_subflow_data > len)
+		return -EINVAL;
+
+	if (sfd->num_subflows || sfd->size_kernel)
+		return -EINVAL;
+
+	return len - sfd->size_subflow_data;
+}
+
+static int mptcp_getsockopt_tcpinfo(struct mptcp_sock *msk, char __user *optval,
+				    int __user *optlen)
+{
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+	unsigned int sfcount = 0, copied = 0;
+	struct mptcp_subflow_data sfd;
+	char __user *infoptr;
+	int len;
+
+	len = mptcp_get_subflow_data(&sfd, optval, optlen);
+	if (len < 0)
+		return len;
+
+	sfd.size_kernel = sizeof(struct tcp_info);
+	sfd.size_user = min_t(unsigned int, sfd.size_user,
+			      sizeof(struct tcp_info));
+
+	infoptr = optval + sfd.size_subflow_data;
+
+	lock_sock(sk);
+
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+
+		++sfcount;
+
+		if (len && len >= sfd.size_user) {
+			struct tcp_info info;
+
+			tcp_get_info(ssk, &info);
+
+			if (copy_to_user(infoptr, &info, sfd.size_user)) {
+				release_sock(sk);
+				return -EFAULT;
+			}
+
+			infoptr += sfd.size_user;
+			copied += sfd.size_user;
+			len -= sfd.size_user;
+		}
+	}
+
+	release_sock(sk);
+
+	sfd.num_subflows = sfcount;
+
+	if (mptcp_put_subflow_data(&sfd, optval, copied, optlen))
+		return -EFAULT;
+
+	return 0;
+}
+
+static void mptcp_get_sub_addrs(const struct sock *sk, struct mptcp_subflow_addrs *a)
+{
+	const struct inet_sock *inet = inet_sk(sk);
+
+	memset(a, 0, sizeof(*a));
+
+	if (sk->sk_family == AF_INET) {
+		a->sin_local.sin_family = AF_INET;
+		a->sin_local.sin_port = inet->inet_sport;
+		a->sin_local.sin_addr.s_addr = inet->inet_rcv_saddr;
+
+		if (!a->sin_local.sin_addr.s_addr)
+			a->sin_local.sin_addr.s_addr = inet->inet_saddr;
+
+		a->sin_remote.sin_family = AF_INET;
+		a->sin_remote.sin_port = inet->inet_dport;
+		a->sin_remote.sin_addr.s_addr = inet->inet_daddr;
+#if IS_ENABLED(CONFIG_IPV6)
+	} else if (sk->sk_family == AF_INET6) {
+		const struct ipv6_pinfo *np = inet6_sk(sk);
+
+		if (WARN_ON_ONCE(!np))
+			return;
+
+		a->sin6_local.sin6_family = AF_INET6;
+		a->sin6_local.sin6_port = inet->inet_sport;
+
+		if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
+			a->sin6_local.sin6_addr = np->saddr;
+		else
+			a->sin6_local.sin6_addr = sk->sk_v6_rcv_saddr;
+
+		a->sin6_remote.sin6_family = AF_INET6;
+		a->sin6_remote.sin6_port = inet->inet_dport;
+		a->sin6_remote.sin6_addr = sk->sk_v6_daddr;
+#endif
+	}
+}
+
+static int mptcp_getsockopt_subflow_addrs(struct mptcp_sock *msk, char __user *optval,
+					  int __user *optlen)
+{
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+	unsigned int sfcount = 0, copied = 0;
+	struct mptcp_subflow_data sfd;
+	char __user *addrptr;
+	int len;
+
+	len = mptcp_get_subflow_data(&sfd, optval, optlen);
+	if (len < 0)
+		return len;
+
+	sfd.size_kernel = sizeof(struct mptcp_subflow_addrs);
+	sfd.size_user = min_t(unsigned int, sfd.size_user,
+			      sizeof(struct mptcp_subflow_addrs));
+
+	addrptr = optval + sfd.size_subflow_data;
+
+	lock_sock(sk);
+
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+
+		++sfcount;
+
+		if (len && len >= sfd.size_user) {
+			struct mptcp_subflow_addrs a;
+
+			mptcp_get_sub_addrs(ssk, &a);
+
+			if (copy_to_user(addrptr, &a, sfd.size_user)) {
+				release_sock(sk);
+				return -EFAULT;
+			}
+
+			addrptr += sfd.size_user;
+			copied += sfd.size_user;
+			len -= sfd.size_user;
+		}
+	}
+
+	release_sock(sk);
+
+	sfd.num_subflows = sfcount;
+
+	if (mptcp_put_subflow_data(&sfd, optval, copied, optlen))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int mptcp_get_full_info(struct mptcp_full_info *mfi,
+			       char __user *optval,
+			       int __user *optlen)
+{
+	int len;
+
+	BUILD_BUG_ON(offsetof(struct mptcp_full_info, mptcp_info) !=
+		     MIN_FULL_INFO_OPTLEN_SIZE);
+
+	if (get_user(len, optlen))
+		return -EFAULT;
+
+	if (len < MIN_FULL_INFO_OPTLEN_SIZE)
+		return -EINVAL;
+
+	memset(mfi, 0, sizeof(*mfi));
+	if (copy_from_user(mfi, optval, MIN_FULL_INFO_OPTLEN_SIZE))
+		return -EFAULT;
+
+	if (mfi->size_tcpinfo_kernel ||
+	    mfi->size_sfinfo_kernel ||
+	    mfi->num_subflows)
+		return -EINVAL;
+
+	if (mfi->size_sfinfo_user > INT_MAX ||
+	    mfi->size_tcpinfo_user > INT_MAX)
+		return -EINVAL;
+
+	return len - MIN_FULL_INFO_OPTLEN_SIZE;
+}
+
+static int mptcp_put_full_info(struct mptcp_full_info *mfi,
+			       char __user *optval,
+			       u32 copylen,
+			       int __user *optlen)
+{
+	copylen += MIN_FULL_INFO_OPTLEN_SIZE;
+	if (put_user(copylen, optlen))
+		return -EFAULT;
+
+	if (copy_to_user(optval, mfi, copylen))
+		return -EFAULT;
+	return 0;
+}
+
+static int mptcp_getsockopt_full_info(struct mptcp_sock *msk, char __user *optval,
+				      int __user *optlen)
+{
+	unsigned int sfcount = 0, copylen = 0;
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+	void __user *tcpinfoptr, *sfinfoptr;
+	struct mptcp_full_info mfi;
+	int len;
+
+	len = mptcp_get_full_info(&mfi, optval, optlen);
+	if (len < 0)
+		return len;
+
+	/* don't bother filling the mptcp info if there is not enough
+	 * user-space-provided storage
+	 */
+	if (len > 0) {
+		mptcp_diag_fill_info(msk, &mfi.mptcp_info);
+		copylen += min_t(unsigned int, len, sizeof(struct mptcp_info));
+	}
+
+	mfi.size_tcpinfo_kernel = sizeof(struct tcp_info);
+	mfi.size_tcpinfo_user = min_t(unsigned int, mfi.size_tcpinfo_user,
+				      sizeof(struct tcp_info));
+	sfinfoptr = u64_to_user_ptr(mfi.subflow_info);
+	mfi.size_sfinfo_kernel = sizeof(struct mptcp_subflow_info);
+	mfi.size_sfinfo_user = min_t(unsigned int, mfi.size_sfinfo_user,
+				     sizeof(struct mptcp_subflow_info));
+	tcpinfoptr = u64_to_user_ptr(mfi.tcp_info);
+
+	lock_sock(sk);
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		struct mptcp_subflow_info sfinfo;
+		struct tcp_info tcp_info;
+
+		if (sfcount++ >= mfi.size_arrays_user)
+			continue;
+
+		/* fetch addr/tcp_info only if the user space buffers
+		 * are wide enough
+		 */
+		memset(&sfinfo, 0, sizeof(sfinfo));
+		sfinfo.id = subflow->subflow_id;
+		if (mfi.size_sfinfo_user >
+		    offsetof(struct mptcp_subflow_info, addrs))
+			mptcp_get_sub_addrs(ssk, &sfinfo.addrs);
+		if (copy_to_user(sfinfoptr, &sfinfo, mfi.size_sfinfo_user))
+			goto fail_release;
+
+		if (mfi.size_tcpinfo_user) {
+			tcp_get_info(ssk, &tcp_info);
+			if (copy_to_user(tcpinfoptr, &tcp_info,
+					 mfi.size_tcpinfo_user))
+				goto fail_release;
+		}
+
+		tcpinfoptr += mfi.size_tcpinfo_user;
+		sfinfoptr += mfi.size_sfinfo_user;
+	}
+	release_sock(sk);
+
+	mfi.num_subflows = sfcount;
+	if (mptcp_put_full_info(&mfi, optval, copylen, optlen))
+		return -EFAULT;
+
+	return 0;
+
+fail_release:
+	release_sock(sk);
+	return -EFAULT;
+}
+
+static int mptcp_put_int_option(struct mptcp_sock *msk, char __user *optval,
+				int __user *optlen, int val)
+{
+	int len;
+
+	if (get_user(len, optlen))
+		return -EFAULT;
+	if (len < 0)
+		return -EINVAL;
+
+	if (len < sizeof(int) && len > 0 && val >= 0 && val <= 255) {
+		unsigned char ucval = (unsigned char)val;
+
+		len = 1;
+		if (put_user(len, optlen))
+			return -EFAULT;
+		if (copy_to_user(optval, &ucval, 1))
+			return -EFAULT;
+	} else {
+		len = min_t(unsigned int, len, sizeof(int));
+		if (put_user(len, optlen))
+			return -EFAULT;
+		if (copy_to_user(optval, &val, len))
+			return -EFAULT;
+	}
+
+	return 0;
+}
+
+static int mptcp_getsockopt_sol_tcp(struct mptcp_sock *msk, int optname,
+				    char __user *optval, int __user *optlen)
+{
+	switch (optname) {
+	case TCP_ULP:
+	case TCP_CONGESTION:
+	case TCP_INFO:
+	case TCP_CC_INFO:
+	case TCP_DEFER_ACCEPT:
+	case TCP_FASTOPEN:
+	case TCP_FASTOPEN_CONNECT:
+	case TCP_FASTOPEN_KEY:
+	case TCP_FASTOPEN_NO_COOKIE:
+		return mptcp_getsockopt_first_sf_only(msk, SOL_TCP, optname,
+						      optval, optlen);
+	case TCP_INQ:
+		return mptcp_put_int_option(msk, optval, optlen, msk->recvmsg_inq);
+	case TCP_CORK:
+		return mptcp_put_int_option(msk, optval, optlen, msk->cork);
+	case TCP_NODELAY:
+		return mptcp_put_int_option(msk, optval, optlen, msk->nodelay);
+	}
+	return -EOPNOTSUPP;
+}
+
+static int mptcp_getsockopt_v4(struct mptcp_sock *msk, int optname,
+			       char __user *optval, int __user *optlen)
+{
+	struct sock *sk = (void *)msk;
+
+	switch (optname) {
+	case IP_TOS:
+		return mptcp_put_int_option(msk, optval, optlen, inet_sk(sk)->tos);
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static int mptcp_getsockopt_sol_mptcp(struct mptcp_sock *msk, int optname,
+				      char __user *optval, int __user *optlen)
+{
+	switch (optname) {
+	case MPTCP_INFO:
+		return mptcp_getsockopt_info(msk, optval, optlen);
+	case MPTCP_FULL_INFO:
+		return mptcp_getsockopt_full_info(msk, optval, optlen);
+	case MPTCP_TCPINFO:
+		return mptcp_getsockopt_tcpinfo(msk, optval, optlen);
+	case MPTCP_SUBFLOW_ADDRS:
+		return mptcp_getsockopt_subflow_addrs(msk, optval, optlen);
+	}
+
+	return -EOPNOTSUPP;
+}
+
+int mptcp_getsockopt(struct sock *sk, int level, int optname,
+		     char __user *optval, int __user *option)
+{
+	struct mptcp_sock *msk = mptcp_sk(sk);
+	struct sock *ssk;
+
+	pr_debug("msk=%p", msk);
+
+	/* @@ the meaning of setsockopt() when the socket is connected and
+	 * there are multiple subflows is not yet defined. It is up to the
+	 * MPTCP-level socket to configure the subflows until the subflow
+	 * is in TCP fallback, when socket options are passed through
+	 * to the one remaining subflow.
+	 */
+	lock_sock(sk);
+	ssk = __mptcp_tcp_fallback(msk);
+	release_sock(sk);
+	if (ssk)
+		return tcp_getsockopt(ssk, level, optname, optval, option);
+
+	if (level == SOL_IP)
+		return mptcp_getsockopt_v4(msk, optname, optval, option);
+	if (level == SOL_TCP)
+		return mptcp_getsockopt_sol_tcp(msk, optname, optval, option);
+	if (level == SOL_MPTCP)
+		return mptcp_getsockopt_sol_mptcp(msk, optname, optval, option);
+	return -EOPNOTSUPP;
+}
+
+static void sync_socket_options(struct mptcp_sock *msk, struct sock *ssk)
+{
+	static const unsigned int tx_rx_locks = SOCK_RCVBUF_LOCK | SOCK_SNDBUF_LOCK;
+	struct sock *sk = (struct sock *)msk;
+
+	if (ssk->sk_prot->keepalive) {
+		if (sock_flag(sk, SOCK_KEEPOPEN))
+			ssk->sk_prot->keepalive(ssk, 1);
+		else
+			ssk->sk_prot->keepalive(ssk, 0);
+	}
+
+	ssk->sk_priority = sk->sk_priority;
+	ssk->sk_bound_dev_if = sk->sk_bound_dev_if;
+	ssk->sk_incoming_cpu = sk->sk_incoming_cpu;
+	ssk->sk_ipv6only = sk->sk_ipv6only;
+	__ip_sock_set_tos(ssk, inet_sk(sk)->tos);
+
+	if (sk->sk_userlocks & tx_rx_locks) {
+		ssk->sk_userlocks |= sk->sk_userlocks & tx_rx_locks;
+		if (sk->sk_userlocks & SOCK_SNDBUF_LOCK) {
+			WRITE_ONCE(ssk->sk_sndbuf, sk->sk_sndbuf);
+			mptcp_subflow_ctx(ssk)->cached_sndbuf = sk->sk_sndbuf;
+		}
+		if (sk->sk_userlocks & SOCK_RCVBUF_LOCK)
+			WRITE_ONCE(ssk->sk_rcvbuf, sk->sk_rcvbuf);
+	}
+
+	if (sock_flag(sk, SOCK_LINGER)) {
+		ssk->sk_lingertime = sk->sk_lingertime;
+		sock_set_flag(ssk, SOCK_LINGER);
+	} else {
+		sock_reset_flag(ssk, SOCK_LINGER);
+	}
+
+	if (sk->sk_mark != ssk->sk_mark) {
+		ssk->sk_mark = sk->sk_mark;
+		sk_dst_reset(ssk);
+	}
+
+	sock_valbool_flag(ssk, SOCK_DBG, sock_flag(sk, SOCK_DBG));
+
+	if (inet_csk(sk)->icsk_ca_ops != inet_csk(ssk)->icsk_ca_ops)
+		tcp_set_congestion_control(ssk, msk->ca_name, false, true);
+	__tcp_sock_set_cork(ssk, !!msk->cork);
+	__tcp_sock_set_nodelay(ssk, !!msk->nodelay);
+
+	inet_assign_bit(TRANSPARENT, ssk, inet_test_bit(TRANSPARENT, sk));
+	inet_assign_bit(FREEBIND, ssk, inet_test_bit(FREEBIND, sk));
+}
+
+static void __mptcp_sockopt_sync(struct mptcp_sock *msk, struct sock *ssk)
+{
+	bool slow = lock_sock_fast(ssk);
+
+	sync_socket_options(msk, ssk);
+
+	unlock_sock_fast(ssk, slow);
+}
+
+void mptcp_sockopt_sync(struct mptcp_sock *msk, struct sock *ssk)
+{
+	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+
+	msk_owned_by_me(msk);
+
+	if (READ_ONCE(subflow->setsockopt_seq) != msk->setsockopt_seq) {
+		__mptcp_sockopt_sync(msk, ssk);
+
+		subflow->setsockopt_seq = msk->setsockopt_seq;
+	}
+}
+
+void mptcp_sockopt_sync_locked(struct mptcp_sock *msk, struct sock *ssk)
+{
+	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+
+	msk_owned_by_me(msk);
+
+	if (READ_ONCE(subflow->setsockopt_seq) != msk->setsockopt_seq) {
+		sync_socket_options(msk, ssk);
+
+		subflow->setsockopt_seq = msk->setsockopt_seq;
+	}
+}