[PATCH] tcp: md5: incorrect tcp_header_len for incoming connections

[PATCH] tcp: md5: incorrect tcp_header_len for incoming connections

[Francesco Ruggeri]

In tcp_create_openreq_child we adjust tcp_header_len for md5 using the
remote address in newsk. But that address is still 0 in newsk at this
point, and it is only set later by the callers (tcp_v[46]_syn_recv_sock).
Use the address from the request socket instead.

Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
---
 net/ipv4/tcp_minisocks.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 6366df7aaf2a..6854bb1fb32b 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -531,7 +531,7 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
 	newtp->tsoffset = treq->ts_off;
 #ifdef CONFIG_TCP_MD5SIG
 	newtp->md5sig_info = NULL;	/*XXX*/
-	if (newtp->af_specific->md5_lookup(sk, newsk))
+	if (treq->af_specific->req_md5_lookup(sk, req_to_sk(req)))
 		newtp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED;
 #endif
 	if (skb->len >= TCP_MSS_DEFAULT + newtp->tcp_header_len)
-- 
2.28.0

Re: [PATCH] tcp: md5: incorrect tcp_header_len for incoming connections

[Eric Dumazet]

On Wed, Apr 20, 2022 at 4:57 PM Francesco Ruggeri <fruggeri@arista.com> wrote:
>
> In tcp_create_openreq_child we adjust tcp_header_len for md5 using the
> remote address in newsk. But that address is still 0 in newsk at this
> point, and it is only set later by the callers (tcp_v[46]_syn_recv_sock).
> Use the address from the request socket instead.
>

Nice catch.

This seems like a day-0 bug, right ?

Do you agree on adding

Fixes: cfb6eeb4c860 ("[TCP]: MD5 Signature Option (RFC2385) support.")

Thanks.

> Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
> ---
>  net/ipv4/tcp_minisocks.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
> index 6366df7aaf2a..6854bb1fb32b 100644
> --- a/net/ipv4/tcp_minisocks.c
> +++ b/net/ipv4/tcp_minisocks.c
> @@ -531,7 +531,7 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
>         newtp->tsoffset = treq->ts_off;
>  #ifdef CONFIG_TCP_MD5SIG
>         newtp->md5sig_info = NULL;      /*XXX*/
> -       if (newtp->af_specific->md5_lookup(sk, newsk))
> +       if (treq->af_specific->req_md5_lookup(sk, req_to_sk(req)))
>                 newtp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED;
>  #endif
>         if (skb->len >= TCP_MSS_DEFAULT + newtp->tcp_header_len)
> --
> 2.28.0
>
>

Re: [PATCH] tcp: md5: incorrect tcp_header_len for incoming connections

[Francesco Ruggeri]

On Wed, Apr 20, 2022 at 5:20 PM Eric Dumazet <edumazet@google.com> wrote:
> On Wed, Apr 20, 2022 at 4:57 PM Francesco Ruggeri <fruggeri@arista.com> wrote:
> This seems like a day-0 bug, right ?
>
> Do you agree on adding
>
> Fixes: cfb6eeb4c860 ("[TCP]: MD5 Signature Option (RFC2385) support.")
>
> Thanks.
>
I also think it is a day-0 bug. Should I resubmit with "Fixes:" ?

Re: [PATCH] tcp: md5: incorrect tcp_header_len for incoming connections

[Eric Dumazet]

On Wed, Apr 20, 2022 at 5:32 PM Francesco Ruggeri <fruggeri@arista.com> wrote:
>
> On Wed, Apr 20, 2022 at 5:20 PM Eric Dumazet <edumazet@google.com> wrote:
> > On Wed, Apr 20, 2022 at 4:57 PM Francesco Ruggeri <fruggeri@arista.com> wrote:
> > This seems like a day-0 bug, right ?
> >
> > Do you agree on adding
> >
> > Fixes: cfb6eeb4c860 ("[TCP]: MD5 Signature Option (RFC2385) support.")
> >
> > Thanks.
> >
> I also think it is a day-0 bug. Should I resubmit with "Fixes:" ?

I think so. It will make things a bit easier for network maintainers,
because I do not think patchwork catches Fixes: tags added during code review.

Also please add the net prefix, as in [PATCH v2 net] title  (look at
the warning at https://patchwork.kernel.org/project/netdevbpf/patch/20220420235659.830155EC021C@us226.sjc.aristanetworks.com/
)

Thanks.