On Wed, Nov 16, 2022 at 4:20 PM Kuniyuki Iwashima <kuniyu@xxxxxxxxxx> wrote:
>
> From: Joanne Koong <joannelkoong@xxxxxxxxx>
> Date: Wed, 16 Nov 2022 16:11:21 -0800
> > On Wed, Nov 16, 2022 at 2:28 PM Kuniyuki Iwashima <kuniyu@xxxxxxxxxx> wrote:
> > >
> > > When connect() is called on a socket bound to the wildcard address,
> > > we change the socket's saddr to a local address. If the socket
> > > fails to connect() to the destination, we have to reset the saddr.
> > >
> > > However, when an error occurs after inet_hash6?_connect() in
> > > (dccp|tcp)_v[46]_conect(), we forget to reset saddr and leave
> > > the socket bound to the address.
> > >
> > > From the user's point of view, whether saddr is reset or not varies
> > > with errno. Let's fix this inconsistent behaviour.
> > >
> > > Note that after this patch, the repro [0] will trigger the WARN_ON()
> > > in inet_csk_get_port() again, but this patch is not buggy and rather
> > > fixes a bug papering over the bhash2's bug for which we need another
> > > fix.
> > >
> > > For the record, the repro causes -EADDRNOTAVAIL in inet_hash6_connect()
> > > by this sequence:
> > >
> > > s1 = socket()
> > > s1.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
> > > s1.bind(('127.0.0.1', 10000))
> > > s1.sendto(b'hello', MSG_FASTOPEN, (('127.0.0.1', 10000)))
> > > # or s1.connect(('127.0.0.1', 10000))
> > >
> > > s2 = socket()
> > > s2.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
> > > s2.bind(('0.0.0.0', 10000))
> > > s2.connect(('127.0.0.1', 10000)) # -EADDRNOTAVAIL
> > >
> > > s2.listen(32) # WARN_ON(inet_csk(sk)->icsk_bind2_hash != tb2);
> > >
> > > [0]: https://syzkaller.appspot.com/bug?extid=015d756bbd1f8b5c8f09
> > >
> > > Fixes: 3df80d9320bc ("[DCCP]: Introduce DCCPv6")
> > > Fixes: 7c657876b63c ("[DCCP]: Initial implementation")
> > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > > Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
> >
> > LGTM. Btw, the 4th patch in this series overwrites these changes by
> > moving this logic into the new inet_bhash2_reset_saddr() function you
> > added, so we could also drop this patch from the series. OTOH, this
> > commit message in this patch has some good background context. So I
> > don't have a preference either way :)
> >
> > Acked-by: Joanne Koong <joannelkoong@xxxxxxxxx>
>
> Thanks for reviewing!
>
> Yes, these changes are overwritten later, but only this patch can be
> backported to other stable versions, so I kept this separated.
>
Gotcha, that makes sense! I will try to get my review of the other 2
patches by tomorrow or Friday.
Thanks for your work on this!
>
> > > ---
> > > net/dccp/ipv4.c | 2 ++
> > > net/dccp/ipv6.c | 2 ++
> > > net/ipv4/tcp_ipv4.c | 2 ++
> > > net/ipv6/tcp_ipv6.c | 2 ++
> > > 4 files changed, 8 insertions(+)
> > >
> > > diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
> > > index 713b7b8dad7e..40640c26680e 100644
> > > --- a/net/dccp/ipv4.c
> > > +++ b/net/dccp/ipv4.c
> > > @@ -157,6 +157,8 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> > > * This unhashes the socket and releases the local port, if necessary.
> > > */
> > > dccp_set_state(sk, DCCP_CLOSED);
> > > + if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> > > + inet_reset_saddr(sk);
> > > ip_rt_put(rt);
> > > sk->sk_route_caps = 0;
> > > inet->inet_dport = 0;
> > > diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
> > > index e57b43006074..626166cb6d7e 100644
> > > --- a/net/dccp/ipv6.c
> > > +++ b/net/dccp/ipv6.c
> > > @@ -985,6 +985,8 @@ static int dccp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
> > >
> > > late_failure:
> > > dccp_set_state(sk, DCCP_CLOSED);
> > > + if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> > > + inet_reset_saddr(sk);
> > > __sk_dst_reset(sk);
> > > failure:
> > > inet->inet_dport = 0;
> > > diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> > > index 87d440f47a70..6a3a732b584d 100644
> > > --- a/net/ipv4/tcp_ipv4.c
> > > +++ b/net/ipv4/tcp_ipv4.c
> > > @@ -343,6 +343,8 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> > > * if necessary.
> > > */
> > > tcp_set_state(sk, TCP_CLOSE);
> > > + if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> > > + inet_reset_saddr(sk);
> > > ip_rt_put(rt);
> > > sk->sk_route_caps = 0;
> > > inet->inet_dport = 0;
> > > diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
> > > index 2a3f9296df1e..81b396e5cf79 100644
> > > --- a/net/ipv6/tcp_ipv6.c
> > > +++ b/net/ipv6/tcp_ipv6.c
> > > @@ -359,6 +359,8 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
> > >
> > > late_failure:
> > > tcp_set_state(sk, TCP_CLOSE);
> > > + if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> > > + inet_reset_saddr(sk);
> > > failure:
> > > inet->inet_dport = 0;
> > > sk->sk_route_caps = 0;
> > > --
> > > 2.30.2
