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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-44a981defb3sm19490140f8f.20.2026.05.02.14.20.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 02 May 2026 14:20:14 -0700 (PDT) From: David Carlier To: mptcp@lists.linux.dev Cc: matttbe@kernel.org, martineau@kernel.org, geliang@kernel.org, pabeni@redhat.com, David Carlier Subject: [PATCH mptcp-next v5 2/4] mptcp: propagate RECVERR sockopts to subflows Date: Sat, 2 May 2026 22:19:58 +0100 Message-ID: <072e47482484e10bc8894fda10e9c1e27ba5a27a.1777756707.git.devnexen@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Propagate IP_RECVERR/IP_RECVERR_RFC4884 and IPV6_RECVERR/IPV6_RECVERR_RFC4884 from the MPTCP socket to existing and future subflows. mptcp_setsockopt_recverr() snapshots optval into a local int, applies it to the parent socket via ip_setsockopt() / ipv6_setsockopt(), bumps msk->setsockopt_seq, and forwards to every subflow via mptcp_setsockopt_all_sf(). Newly-joining subflows pick up the four RECVERR bits through sync_socket_options() now that MPTCP_INET_FLAGS_MASK covers them. mptcp_setsockopt_all_sf() skips IPv4 subflows when called with SOL_IPV6 to avoid the -ENOPROTOOPT that ip_setsockopt() returns on level mismatch in AF_INET6 msks carrying IPv4 subflows. Suggested-by: Paolo Abeni Assisted-by: Codex:gpt-5 Signed-off-by: David Carlier --- net/mptcp/sockopt.c | 95 ++++++++++++++++++++++++++++++++++++--------- 1 file changed, 77 insertions(+), 18 deletions(-) diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c index b828cdd9657c..56265b076f6e 100644 --- a/net/mptcp/sockopt.c +++ b/net/mptcp/sockopt.c @@ -8,6 +8,8 @@ =20 #include #include +#include +#include #include #include #include @@ -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)) =20 static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk) { @@ -388,6 +394,57 @@ static int mptcp_setsockopt_sol_socket(struct mptcp_so= ck *msk, int optname, return -EOPNOTSUPP; } =20 +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 =3D 0; + + mptcp_for_each_subflow(msk, subflow) { + struct sock *ssk =3D mptcp_subflow_tcp_sock(subflow); + + if (level =3D=3D SOL_IPV6 && ssk->sk_family !=3D AF_INET6) + continue; + + ret =3D tcp_setsockopt(ssk, level, optname, optval, optlen); + if (ret) + break; + } + return ret; +} + +static int mptcp_setsockopt_recverr(struct mptcp_sock *msk, int level, + int optname, sockptr_t optval, + unsigned int optlen) +{ + struct sock *sk =3D (struct sock *)msk; + int val, ret; + + if (optlen < sizeof(int)) + return -EINVAL; + if (copy_from_sockptr(&val, optval, sizeof(val))) + return -EFAULT; + + if (level =3D=3D SOL_IP) + ret =3D ip_setsockopt(sk, level, optname, KERNEL_SOCKPTR(&val), sizeof(v= al)); + +#if IS_ENABLED(CONFIG_IPV6) + else if (level =3D=3D SOL_IPV6) + ret =3D ipv6_setsockopt(sk, level, optname, KERNEL_SOCKPTR(&val), sizeof= (val)); +#endif + else + return -EOPNOTSUPP; + if (ret) + return ret; + + lock_sock(sk); + sockopt_seq_inc(msk); + ret =3D mptcp_setsockopt_all_sf(msk, level, optname, KERNEL_SOCKPTR(&val)= , sizeof(val)); + release_sock(sk); + return ret; +} + static int mptcp_setsockopt_v6(struct mptcp_sock *msk, int optname, sockptr_t optval, unsigned int optlen) { @@ -430,6 +487,10 @@ static int mptcp_setsockopt_v6(struct mptcp_sock *msk,= int optname, =20 release_sock(sk); break; + case IPV6_RECVERR: + case IPV6_RECVERR_RFC4884: + ret =3D mptcp_setsockopt_recverr(msk, SOL_IPV6, optname, optval, optlen); + break; } =20 return ret; @@ -775,6 +836,9 @@ 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_recverr(msk, SOL_IP, optname, optval, optlen); } =20 return -EOPNOTSUPP; @@ -802,23 +866,6 @@ static int mptcp_setsockopt_first_sf_only(struct mptcp= _sock *msk, int level, int return ret; } =20 -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 =3D 0; - - mptcp_for_each_subflow(msk, subflow) { - struct sock *ssk =3D mptcp_subflow_tcp_sock(subflow); - - ret =3D 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 +1510,12 @@ static int mptcp_getsockopt_v4(struct mptcp_sock *ms= k, 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)); } =20 return -EOPNOTSUPP; @@ -1483,6 +1536,12 @@ static int mptcp_getsockopt_v6(struct mptcp_sock *ms= k, 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)); } =20 return -EOPNOTSUPP; --=20 2.53.0