| Message ID | 20231121020111.1143180-7-dima@arista.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [1/7] Documentation/tcp: Fix an obvious typo | expand |
On Tue, Nov 21, 2023 at 3:01 AM Dmitry Safonov <dima@arista.com> wrote: > > SNEs need READ_ONCE()/WRITE_ONCE() for access as they can be written and > read at the same time. > > This is actually a shame: I planned to send it in TCP-AO patches, but > it seems I've chosen a wrong commit to git-commit-fixup some time ago. > It ended up in a commit that adds a selftest. Human factor. > > Fixes: 64382c71a557 ("net/tcp: Add TCP-AO SNE support") > Signed-off-by: Dmitry Safonov <dima@arista.com> > --- > net/ipv4/tcp_ao.c | 4 ++-- > net/ipv4/tcp_input.c | 4 ++-- > 2 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c > index 122ff58168ee..9b7f1970c2e9 100644 > --- a/net/ipv4/tcp_ao.c > +++ b/net/ipv4/tcp_ao.c > @@ -956,8 +956,8 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb, > if (unlikely(th->syn && !th->ack)) > goto verify_hash; > > - sne = tcp_ao_compute_sne(info->rcv_sne, tcp_sk(sk)->rcv_nxt, > - ntohl(th->seq)); > + sne = tcp_ao_compute_sne(READ_ONCE(info->rcv_sne), > + tcp_sk(sk)->rcv_nxt, ntohl(th->seq)); I think this is a wrong fix. Something is definitely fishy here. Update side should only happen for an established socket ? And the read side should have locked the socket before calling tcp_inbound_ao_hash(), otherwise reading other fields (like tcp_sk(sk)->rcv_nxt) would be racy anyway. > /* Established socket, traffic key are cached */ > traffic_key = rcv_other_key(key); > err = tcp_ao_verify_hash(sk, skb, family, info, aoh, key, > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c > index bcb55d98004c..78896c8be0d4 100644 > --- a/net/ipv4/tcp_input.c > +++ b/net/ipv4/tcp_input.c tcp_snd_sne_update() definitely only deals with full sockets (TCP_AO_ESTABLISHED) > @@ -3583,7 +3583,7 @@ static void tcp_snd_sne_update(struct tcp_sock *tp, u32 ack) > ao = rcu_dereference_protected(tp->ao_info, > lockdep_sock_is_held((struct sock *)tp)); > if (ao && ack < tp->snd_una) > - ao->snd_sne++; > + WRITE_ONCE(ao->snd_sne, ao->snd_sne + 1); > #endif > } > > @@ -3609,7 +3609,7 @@ static void tcp_rcv_sne_update(struct tcp_sock *tp, u32 seq) > ao = rcu_dereference_protected(tp->ao_info, > lockdep_sock_is_held((struct sock *)tp)); > if (ao && seq < tp->rcv_nxt) > - ao->rcv_sne++; > + WRITE_ONCE(ao->rcv_sne, ao->rcv_sne + 1); > #endif > } > > -- > 2.42.0 >
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c index 122ff58168ee..9b7f1970c2e9 100644 --- a/net/ipv4/tcp_ao.c +++ b/net/ipv4/tcp_ao.c @@ -956,8 +956,8 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb, if (unlikely(th->syn && !th->ack)) goto verify_hash; - sne = tcp_ao_compute_sne(info->rcv_sne, tcp_sk(sk)->rcv_nxt, - ntohl(th->seq)); + sne = tcp_ao_compute_sne(READ_ONCE(info->rcv_sne), + tcp_sk(sk)->rcv_nxt, ntohl(th->seq)); /* Established socket, traffic key are cached */ traffic_key = rcv_other_key(key); err = tcp_ao_verify_hash(sk, skb, family, info, aoh, key, diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index bcb55d98004c..78896c8be0d4 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3583,7 +3583,7 @@ static void tcp_snd_sne_update(struct tcp_sock *tp, u32 ack) ao = rcu_dereference_protected(tp->ao_info, lockdep_sock_is_held((struct sock *)tp)); if (ao && ack < tp->snd_una) - ao->snd_sne++; + WRITE_ONCE(ao->snd_sne, ao->snd_sne + 1); #endif } @@ -3609,7 +3609,7 @@ static void tcp_rcv_sne_update(struct tcp_sock *tp, u32 seq) ao = rcu_dereference_protected(tp->ao_info, lockdep_sock_is_held((struct sock *)tp)); if (ao && seq < tp->rcv_nxt) - ao->rcv_sne++; + WRITE_ONCE(ao->rcv_sne, ao->rcv_sne + 1); #endif }
SNEs need READ_ONCE()/WRITE_ONCE() for access as they can be written and read at the same time. This is actually a shame: I planned to send it in TCP-AO patches, but it seems I've chosen a wrong commit to git-commit-fixup some time ago. It ended up in a commit that adds a selftest. Human factor. Fixes: 64382c71a557 ("net/tcp: Add TCP-AO SNE support") Signed-off-by: Dmitry Safonov <dima@arista.com> --- net/ipv4/tcp_ao.c | 4 ++-- net/ipv4/tcp_input.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-)