[v4] mptcp: MSG_ERRQUEUE support on the parent socket

[PATCH mptcp-next v4 2/4] mptcp: propagate RECVERR sockopts to subflows

Posted by David Carlier 1 month, 2 weeks ago

Propagate IP_RECVERR/IP_RECVERR_RFC4884 and
IPV6_RECVERR/IPV6_RECVERR_RFC4884 from the MPTCP socket to existing
and future subflows. The setsockopt path forwards each option to
every subflow via mptcp_setsockopt_all_sf(); newly-joining subflows
inherit the four RECVERR bits through sync_socket_options() now that
MPTCP_INET_FLAGS_MASK covers them.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Assisted-by: Codex:gpt-5
Signed-off-by: David Carlier <devnexen@gmail.com>
---
 net/mptcp/sockopt.c | 97 ++++++++++++++++++++++++++++++++++++---------
 1 file changed, 79 insertions(+), 18 deletions(-)

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index 41c9dc9cf95e..171e83e66a97 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -8,6 +8,8 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
 #include <net/sock.h>
 #include <net/protocol.h>
 #include <net/tcp.h>
@@ -19,7 +21,11 @@
 #define MPTCP_INET_FLAGS_MASK \
 	(BIT(INET_FLAGS_TRANSPARENT) | \
 	 BIT(INET_FLAGS_FREEBIND) | \
-	 BIT(INET_FLAGS_BIND_ADDRESS_NO_PORT))
+	 BIT(INET_FLAGS_BIND_ADDRESS_NO_PORT) | \
+	 BIT(INET_FLAGS_RECVERR) | \
+	 BIT(INET_FLAGS_RECVERR_RFC4884) | \
+	 BIT(INET_FLAGS_RECVERR6) | \
+	 BIT(INET_FLAGS_RECVERR6_RFC4884))
 
 static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk)
 {
@@ -388,6 +394,41 @@ static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname,
 	return -EOPNOTSUPP;
 }
 
+static int mptcp_setsockopt_all_sf(struct mptcp_sock *msk, int level,
+				   int optname, sockptr_t optval,
+				   unsigned int optlen)
+{
+	struct mptcp_subflow_context *subflow;
+	int ret = 0;
+
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+
+		ret = tcp_setsockopt(ssk, level, optname, optval, optlen);
+		if (ret)
+			break;
+	}
+	return ret;
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+static int mptcp_setsockopt_v6_recverr(struct mptcp_sock *msk, int optname,
+				       sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = (struct sock *)msk;
+	int ret;
+
+	ret = ipv6_setsockopt(sk, SOL_IPV6, optname, optval, optlen);
+	if (ret)
+		return ret;
+
+	lock_sock(sk);
+	ret = mptcp_setsockopt_all_sf(msk, SOL_IPV6, optname, optval, optlen);
+	release_sock(sk);
+	return ret;
+}
+#endif
+
 static int mptcp_setsockopt_v6(struct mptcp_sock *msk, int optname,
 			       sockptr_t optval, unsigned int optlen)
 {
@@ -430,6 +471,12 @@ static int mptcp_setsockopt_v6(struct mptcp_sock *msk, int optname,
 
 		release_sock(sk);
 		break;
+#if IS_ENABLED(CONFIG_IPV6)
+	case IPV6_RECVERR:
+	case IPV6_RECVERR_RFC4884:
+		ret = mptcp_setsockopt_v6_recverr(msk, optname, optval, optlen);
+		break;
+#endif
 	}
 
 	return ret;
@@ -764,6 +811,22 @@ static int mptcp_setsockopt_v4_set_tos(struct mptcp_sock *msk, int optname,
 	return 0;
 }
 
+static int mptcp_setsockopt_v4_recverr(struct mptcp_sock *msk, int optname,
+				       sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = (struct sock *)msk;
+	int ret;
+
+	ret = ip_setsockopt(sk, SOL_IP, optname, optval, optlen);
+	if (ret)
+		return ret;
+
+	lock_sock(sk);
+	ret = mptcp_setsockopt_all_sf(msk, SOL_IP, optname, optval, optlen);
+	release_sock(sk);
+	return ret;
+}
+
 static int mptcp_setsockopt_v4(struct mptcp_sock *msk, int optname,
 			       sockptr_t optval, unsigned int optlen)
 {
@@ -775,6 +838,9 @@ static int mptcp_setsockopt_v4(struct mptcp_sock *msk, int optname,
 		return mptcp_setsockopt_sol_ip_set(msk, optname, optval, optlen);
 	case IP_TOS:
 		return mptcp_setsockopt_v4_set_tos(msk, optname, optval, optlen);
+	case IP_RECVERR:
+	case IP_RECVERR_RFC4884:
+		return mptcp_setsockopt_v4_recverr(msk, optname, optval, optlen);
 	}
 
 	return -EOPNOTSUPP;
@@ -802,23 +868,6 @@ static int mptcp_setsockopt_first_sf_only(struct mptcp_sock *msk, int level, int
 	return ret;
 }
 
-static int mptcp_setsockopt_all_sf(struct mptcp_sock *msk, int level,
-				   int optname, sockptr_t optval,
-				   unsigned int optlen)
-{
-	struct mptcp_subflow_context *subflow;
-	int ret = 0;
-
-	mptcp_for_each_subflow(msk, subflow) {
-		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-
-		ret = tcp_setsockopt(ssk, level, optname, optval, optlen);
-		if (ret)
-			break;
-	}
-	return ret;
-}
-
 static int mptcp_setsockopt_sol_tcp(struct mptcp_sock *msk, int optname,
 				    sockptr_t optval, unsigned int optlen)
 {
@@ -1463,6 +1512,12 @@ static int mptcp_getsockopt_v4(struct mptcp_sock *msk, int optname,
 	case IP_LOCAL_PORT_RANGE:
 		return mptcp_put_int_option(msk, optval, optlen,
 				READ_ONCE(inet_sk(sk)->local_port_range));
+	case IP_RECVERR:
+		return mptcp_put_int_option(msk, optval, optlen,
+				inet_test_bit(RECVERR, sk));
+	case IP_RECVERR_RFC4884:
+		return mptcp_put_int_option(msk, optval, optlen,
+				inet_test_bit(RECVERR_RFC4884, sk));
 	}
 
 	return -EOPNOTSUPP;
@@ -1483,6 +1538,12 @@ static int mptcp_getsockopt_v6(struct mptcp_sock *msk, int optname,
 	case IPV6_FREEBIND:
 		return mptcp_put_int_option(msk, optval, optlen,
 					    inet_test_bit(FREEBIND, sk));
+	case IPV6_RECVERR:
+		return mptcp_put_int_option(msk, optval, optlen,
+					    inet6_test_bit(RECVERR6, sk));
+	case IPV6_RECVERR_RFC4884:
+		return mptcp_put_int_option(msk, optval, optlen,
+					    inet6_test_bit(RECVERR6_RFC4884, sk));
 	}
 
 	return -EOPNOTSUPP;
-- 
2.53.0

Re: [PATCH mptcp-next v4 2/4] mptcp: propagate RECVERR sockopts to subflows

Posted by Matthieu Baerts 1 month, 1 week ago

On 27/04/2026 23:10, David Carlier wrote:
> Propagate IP_RECVERR/IP_RECVERR_RFC4884 and
> IPV6_RECVERR/IPV6_RECVERR_RFC4884 from the MPTCP socket to existing
> and future subflows. The setsockopt path forwards each option to
> every subflow via mptcp_setsockopt_all_sf(); newly-joining subflows
> inherit the four RECVERR bits through sync_socket_options() now that
> MPTCP_INET_FLAGS_MASK covers them.
> 
> Suggested-by: Paolo Abeni <pabeni@redhat.com>
> Assisted-by: Codex:gpt-5
> Signed-off-by: David Carlier <devnexen@gmail.com>
> ---
>  net/mptcp/sockopt.c | 97 ++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 79 insertions(+), 18 deletions(-)
> 
> diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
> index 41c9dc9cf95e..171e83e66a97 100644
> --- a/net/mptcp/sockopt.c
> +++ b/net/mptcp/sockopt.c

(...)

> @@ -388,6 +394,41 @@ static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname,
>  	return -EOPNOTSUPP;
>  }
>  
> +static int mptcp_setsockopt_all_sf(struct mptcp_sock *msk, int level,
> +				   int optname, sockptr_t optval,
> +				   unsigned int optlen)
> +{
> +	struct mptcp_subflow_context *subflow;
> +	int ret = 0;
> +
> +	mptcp_for_each_subflow(msk, subflow) {
> +		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
> +
> +		ret = tcp_setsockopt(ssk, level, optname, optval, optlen);
> +		if (ret)
> +			break;
> +	}
> +	return ret;
> +}
> +
> +#if IS_ENABLED(CONFIG_IPV6)
> +static int mptcp_setsockopt_v6_recverr(struct mptcp_sock *msk, int optname,
> +				       sockptr_t optval, unsigned int optlen)
> +{
> +	struct sock *sk = (struct sock *)msk;
> +	int ret;
> +
> +	ret = ipv6_setsockopt(sk, SOL_IPV6, optname, optval, optlen);
> +	if (ret)
> +		return ret;
> +
> +	lock_sock(sk);
> +	ret = mptcp_setsockopt_all_sf(msk, SOL_IPV6, optname, optval, optlen);
> +	release_sock(sk);
> +	return ret;
> +}
> +#endif

Maybe you could have one generic helper to call xxx_setsockopt() on the
MPTCP socket, and then call mptcp_setsockopt_all_sf(). You can pass the
level, and call the right function.

(...)

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.

[PATCH mptcp-next v4 1/4] mptcp: sockopt: factor inet_flags propagation into a mask
[PATCH mptcp-next v4 2/4] mptcp: propagate RECVERR sockopts to subflows
[PATCH mptcp-next v4 3/4] mptcp: support MSG_ERRQUEUE on the parent socket
[PATCH mptcp-next v4 4/4] selftests: mptcp: cover IP_RECVERR sockopt propagation