| Message ID | 20231121020111.1143180-5-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| State | Superseded |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: > > TCP_LISTEN sockets are not connected to any peer, so having > current_key/rnext_key doesn't make sense. > > The userspace may falter over this issue by setting current or rnext > TCP-AO key before listen() syscall. setsockopt(TCP_AO_DEL_KEY) doesn't > allow removing a key that is in use (in accordance to RFC 5925), so > it might be inconvenient to have keys that can be destroyed only with > listener socket. I think this is the wrong way to solve this issue. listen() should not mess with anything else than socket state. > > Fixes: 4954f17ddefc ("net/tcp: Introduce TCP_AO setsockopt()s") > Signed-off-by: Dmitry Safonov <dima@arista.com> > --- > include/net/tcp_ao.h | 5 +++++ > net/ipv4/af_inet.c | 1 + > net/ipv4/tcp_ao.c | 14 ++++++++++++++ > 3 files changed, 20 insertions(+) > > diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h > index 647781080613..e36057ca5ed8 100644 > --- a/include/net/tcp_ao.h > +++ b/include/net/tcp_ao.h > @@ -270,6 +270,7 @@ int tcp_v6_ao_synack_hash(char *ao_hash, struct tcp_ao_key *ao_key, > void tcp_ao_established(struct sock *sk); > void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb); > void tcp_ao_connect_init(struct sock *sk); > +void tcp_ao_listen(struct sock *sk); > void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb, > struct tcp_request_sock *treq, > unsigned short int family, int l3index); > @@ -330,6 +331,10 @@ static inline void tcp_ao_connect_init(struct sock *sk) > { > } > > +static inline void tcp_ao_listen(struct sock *sk) > +{ > +} > + > static inline int tcp_ao_get_mkts(struct sock *sk, sockptr_t optval, sockptr_t optlen) > { > return -ENOPROTOOPT; > diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c > index fb81de10d332..a08d1266344f 100644 > --- a/net/ipv4/af_inet.c > +++ b/net/ipv4/af_inet.c > @@ -200,6 +200,7 @@ int __inet_listen_sk(struct sock *sk, int backlog) > * we can only allow the backlog to be adjusted. > */ > if (old_state != TCP_LISTEN) { > + tcp_ao_listen(sk); Ouch... Please add your hook in tcp_disconnect() instead of this layering violation. I think you missed the fact that applications can call listen(fd, backlog) multiple times, if they need to dynamically adjust backlog.
On 11/21/23 08:18, Eric Dumazet wrote: > On Tue, Nov 21, 2023 at 3:01 AM Dmitry Safonov <dima@arista.com> wrote: >> >> TCP_LISTEN sockets are not connected to any peer, so having >> current_key/rnext_key doesn't make sense. >> >> The userspace may falter over this issue by setting current or rnext >> TCP-AO key before listen() syscall. setsockopt(TCP_AO_DEL_KEY) doesn't >> allow removing a key that is in use (in accordance to RFC 5925), so >> it might be inconvenient to have keys that can be destroyed only with >> listener socket. > > I think this is the wrong way to solve this issue. listen() should not > mess with anything else than socket state. > >> >> Fixes: 4954f17ddefc ("net/tcp: Introduce TCP_AO setsockopt()s") >> Signed-off-by: Dmitry Safonov <dima@arista.com> [..] >> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c >> index fb81de10d332..a08d1266344f 100644 >> --- a/net/ipv4/af_inet.c >> +++ b/net/ipv4/af_inet.c >> @@ -200,6 +200,7 @@ int __inet_listen_sk(struct sock *sk, int backlog) >> * we can only allow the backlog to be adjusted. >> */ >> if (old_state != TCP_LISTEN) { >> + tcp_ao_listen(sk); > > Ouch... > > Please add your hook in tcp_disconnect() instead of this layering violation. > > I think you missed the fact that applications can call listen(fd, > backlog) multiple times, > if they need to dynamically adjust backlog. Hmm, unsure, I've probably failed at describing the issue or failing to understand your reply :-) Let me try again: 1. sk = socket(AF_*, SOCK_STREAM, IPPROTO_TCP) 2. setsockopt(sk, TCP_AO_ADD_KEY, ...) - adding a key to use later 3. setsockopt(sk, IPPROTO_TCP, TCP_AO_INFO, set_current=1) - could be done straight on adding a key at (2), but for an example, explicitely 4.a. connect(sk, peer) - all as expected, the current key will be the one that is used for SYN (and ending ACK if the peer doesn't request to switch) 4.b listen(sk, ...) - userspace shoots itself in foot: the current_key has no usage on TCP_LISTEN, so it just "hangs" as a pointer until the socket gets destroyed. An alternative fix would be to make setsockopt(TCP_AO_DEL_KEY) remove a key even if it's current_key on TCP_LISTEN, re-setting that to NULL. Now as I described, somewhat feeling like the alternative fix sounds better. Will proceed with that for v2. Thanks, Dmitry
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h index 647781080613..e36057ca5ed8 100644 --- a/include/net/tcp_ao.h +++ b/include/net/tcp_ao.h @@ -270,6 +270,7 @@ int tcp_v6_ao_synack_hash(char *ao_hash, struct tcp_ao_key *ao_key, void tcp_ao_established(struct sock *sk); void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb); void tcp_ao_connect_init(struct sock *sk); +void tcp_ao_listen(struct sock *sk); void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb, struct tcp_request_sock *treq, unsigned short int family, int l3index); @@ -330,6 +331,10 @@ static inline void tcp_ao_connect_init(struct sock *sk) { } +static inline void tcp_ao_listen(struct sock *sk) +{ +} + static inline int tcp_ao_get_mkts(struct sock *sk, sockptr_t optval, sockptr_t optlen) { return -ENOPROTOOPT; diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index fb81de10d332..a08d1266344f 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -200,6 +200,7 @@ int __inet_listen_sk(struct sock *sk, int backlog) * we can only allow the backlog to be adjusted. */ if (old_state != TCP_LISTEN) { + tcp_ao_listen(sk); /* Enable TFO w/o requiring TCP_FASTOPEN socket option. * Note that only TCP sockets (SOCK_STREAM) will reach here. * Also fastopen backlog may already been set via the option diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c index c8be1d526eac..71c8c9c59642 100644 --- a/net/ipv4/tcp_ao.c +++ b/net/ipv4/tcp_ao.c @@ -1052,6 +1052,20 @@ static int tcp_ao_cache_traffic_keys(const struct sock *sk, return ret; } +void tcp_ao_listen(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct tcp_ao_info *ao_info; + + ao_info = rcu_dereference_protected(tp->ao_info, + lockdep_sock_is_held(sk)); + if (!ao_info) + return; + + WRITE_ONCE(ao_info->current_key, NULL); + WRITE_ONCE(ao_info->rnext_key, NULL); +} + void tcp_ao_connect_init(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk);
TCP_LISTEN sockets are not connected to any peer, so having current_key/rnext_key doesn't make sense. The userspace may falter over this issue by setting current or rnext TCP-AO key before listen() syscall. setsockopt(TCP_AO_DEL_KEY) doesn't allow removing a key that is in use (in accordance to RFC 5925), so it might be inconvenient to have keys that can be destroyed only with listener socket. Fixes: 4954f17ddefc ("net/tcp: Introduce TCP_AO setsockopt()s") Signed-off-by: Dmitry Safonov <dima@arista.com> --- include/net/tcp_ao.h | 5 +++++ net/ipv4/af_inet.c | 1 + net/ipv4/tcp_ao.c | 14 ++++++++++++++ 3 files changed, 20 insertions(+)