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charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2024-05-08 at 11:44 +0200, Matthieu Baerts (NGI0) wrote: > SO_KEEPALIVE support has been added a while ago, as part of a series > "adding SOL_SOCKET" support. To have a full control of this keep-alive > feature, it is important to also support TCP_KEEP* socket options at the > SOL_TCP level. >=20 > Supporting them on the setsockopt() part is easy, it is just a matter of > remembering each value in the MPTCP sock structure, and calling > tcp_sock_set_keep*() helpers on each subflow. If the value is not > modified (0), calling these helpers will not do anything. For the > getsockopt() part, the corresponding value from the MPTCP sock structure > or the default one is simply returned. >=20 > It looks important for kernels supporting SO_KEEPALIVE, to also support > TCP_KEEP* options as well: some apps seem to (wrongly) consider that if > the former is supported, the latter ones will be supported as well. But > also, not having this simple and isolated change is preventing MPTCP > support in some apps, and libraries like GoLang [1]. This is why this > patch is seen as a fix. >=20 > Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/383 > Fixes: 1b3e7ede1365 ("mptcp: setsockopt: handle SO_KEEPALIVE and SO_PRIOR= ITY") > Link: https://github.com/golang/go/issues/56539 [1] > Signed-off-by: Matthieu Baerts (NGI0) > --- > net/mptcp/protocol.h | 3 +++ > net/mptcp/sockopt.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++= ++++++ > 2 files changed, 60 insertions(+) >=20 > diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h > index c09357e04f23..8c7ab1d50c75 100644 > --- a/net/mptcp/protocol.h > +++ b/net/mptcp/protocol.h > @@ -309,6 +309,9 @@ struct mptcp_sock { > =09=09=09in_accept_queue:1, > =09=09=09free_first:1, > =09=09=09rcvspace_init:1; > +=09u8=09=09keepalive_cnt; > +=09unsigned int=09keepalive_idle; > +=09unsigned int=09keepalive_intvl; It's a bit a pity we have to duplicate such values in all the subflows _and_ in the msk... > =09u32=09=09notsent_lowat; > =09struct work_struct work; > =09struct sk_buff *ooo_last_skb; > diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c > index d9f0d36e24ad..794d8b63024a 100644 > --- a/net/mptcp/sockopt.c > +++ b/net/mptcp/sockopt.c > @@ -622,6 +622,30 @@ static int mptcp_setsockopt_sol_tcp_congestion(struc= t mptcp_sock *msk, sockptr_t > =09return ret; > } > =20 > +static int __mptcp_setsockopt_set_val(struct mptcp_sock *msk, int max, > +=09=09=09=09 int (*set_val)(struct sock *, int), > +=09=09=09=09 unsigned int *msk_val, int val) > +{ > +=09struct mptcp_subflow_context *subflow; > +=09int ret =3D 0; > + > +=09if (val < 1 || val > max) > +=09=09return -EINVAL; I think it would be better just skip this check, to avoid copying more logic from TCP, and do the store and sockopt_seq_inc() only when the operation is successful on all the subflows. > + > +=09*msk_val =3D val; > +=09sockopt_seq_inc(msk); > + > +=09mptcp_for_each_subflow(msk, subflow) { > +=09=09struct sock *ssk =3D mptcp_subflow_tcp_sock(subflow); > + > +=09=09lock_sock(ssk); > +=09=09ret |=3D set_val(ssk, val); the above produces 'reasonable' return code only if all 'set_val' calls will return the same error code. That expectation should be respected by the existing code, but what about keeping the first error code only? e.g: =09int err, ret; =09// ... =09=09ret =3D set_val(ssk, val); =09=09err =3D err ?: ret; =09// ... =09return err; > +=09=09release_sock(ssk); > +=09} > + > +=09return ret; > +} > + > static int __mptcp_setsockopt_sol_tcp_cork(struct mptcp_sock *msk, int v= al) > { > =09struct mptcp_subflow_context *subflow; > @@ -818,6 +842,22 @@ static int mptcp_setsockopt_sol_tcp(struct mptcp_soc= k *msk, int optname, > =09case TCP_NODELAY: > =09=09ret =3D __mptcp_setsockopt_sol_tcp_nodelay(msk, val); > =09=09break; > +=09case TCP_KEEPIDLE: > +=09=09ret =3D __mptcp_setsockopt_set_val(msk, MAX_TCP_KEEPIDLE, > +=09=09=09=09=09=09 &tcp_sock_set_keepidle_locked, > +=09=09=09=09=09=09 &msk->keepalive_idle, val); > +=09=09break; > +=09case TCP_KEEPINTVL: > +=09=09ret =3D __mptcp_setsockopt_set_val(msk, MAX_TCP_KEEPINTVL, > +=09=09=09=09=09=09 &tcp_sock_set_keepintvl, > +=09=09=09=09=09=09 &msk->keepalive_intvl, val); > +=09=09break; > +=09case TCP_KEEPCNT: > +=09=09ret =3D __mptcp_setsockopt_set_val(msk, MAX_TCP_KEEPCNT, > +=09=09=09=09=09=09 &tcp_sock_set_keepcnt, > +=09=09=09=09=09=09 (unsigned int *)&msk->keepalive_cnt, keepalive_cnt is 'u8' so the above will be technically a buffer overflow ;) If we keep 'keepalive_cnt' in msk, it has to become an=C2=A0'unsigned int' > +=09=09=09=09=09=09 val); > +=09=09break; > =09default: > =09=09ret =3D -ENOPROTOOPT; > =09} > @@ -1332,6 +1372,8 @@ static int mptcp_put_int_option(struct mptcp_sock *= msk, char __user *optval, > static int mptcp_getsockopt_sol_tcp(struct mptcp_sock *msk, int optname, > =09=09=09=09 char __user *optval, int __user *optlen) > { > +=09struct sock *sk =3D (void *)msk; > + > =09switch (optname) { > =09case TCP_ULP: > =09case TCP_CONGESTION: > @@ -1352,6 +1394,18 @@ static int mptcp_getsockopt_sol_tcp(struct mptcp_s= ock *msk, int optname, > =09=09return mptcp_put_int_option(msk, optval, optlen, msk->nodelay); > =09case TCP_NOTSENT_LOWAT: > =09=09return mptcp_put_int_option(msk, optval, optlen, msk->notsent_lowa= t); > +=09case TCP_KEEPIDLE: > +=09=09return mptcp_put_int_option(msk, optval, optlen, > +=09=09=09=09=09 msk->keepalive_idle ? : > +=09=09=09=09=09 READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_keepalive_tim= e) / HZ); If we force the first subflow to be present/allocated at setsockopt time, then here we could: =09case TCP_KEEPIDLE: =09case TCP_KEEPIDLE: =09case TCP_KEEPCNT: =09=09return do_tcp_getsockopt(msk->first, SOL_TCP, optname,=C2=A0 =09=09=09=09=09USER_SOCKPTR(optval), =09=09=09=09=09USER_SOCKPTR(optlen)); > +=09case TCP_KEEPINTVL: > +=09=09return mptcp_put_int_option(msk, optval, optlen, > +=09=09=09=09=09 msk->keepalive_intvl ? : > +=09=09=09=09=09 READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_keepalive_int= vl) / HZ); > +=09case TCP_KEEPCNT: > +=09=09return mptcp_put_int_option(msk, optval, optlen, > +=09=09=09=09=09 msk->keepalive_cnt ? : > +=09=09=09=09=09 READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_keepalive_pro= bes)); > =09} > =09return -EOPNOTSUPP; > } > @@ -1467,6 +1521,9 @@ static void sync_socket_options(struct mptcp_sock *= msk, struct sock *ssk) > =09=09tcp_set_congestion_control(ssk, msk->ca_name, false, true); > =09__tcp_sock_set_cork(ssk, !!msk->cork); > =09__tcp_sock_set_nodelay(ssk, !!msk->nodelay); > +=09tcp_sock_set_keepidle_locked(ssk, msk->keepalive_idle); > +=09tcp_sock_set_keepintvl(ssk, msk->keepalive_intvl); > +=09tcp_sock_set_keepcnt(ssk, msk->keepalive_cnt); > =20 > =09inet_assign_bit(TRANSPARENT, ssk, inet_test_bit(TRANSPARENT, sk)); > =09inet_assign_bit(FREEBIND, ssk, inet_test_bit(FREEBIND, sk)); >=20