netdev - Re: [bpf PATCH 1/2] bpf, sockmap: fix sk->prot unhash op reset

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <605bf553d16f_64fde2081@john-XPS-13-9370.notmuch>
Date:   Wed, 24 Mar 2021 19:28:35 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     Cong Wang <xiyou.wangcong@...il.com>,
        John Fastabend <john.fastabend@...il.com>
Cc:     Andrii Nakryiko <andrii@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...com>, bpf <bpf@...r.kernel.org>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Lorenz Bauer <lmb@...udflare.com>
Subject: Re: [bpf PATCH 1/2] bpf, sockmap: fix sk->prot unhash op reset

Cong Wang wrote:
> On Wed, Mar 24, 2021 at 1:59 PM John Fastabend <john.fastabend@...il.com> wrote:
> > diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
> > index 47b7c5334c34..ecb5634b4c4a 100644
> > --- a/net/tls/tls_main.c
> > +++ b/net/tls/tls_main.c
> > @@ -754,6 +754,12 @@ static void tls_update(struct sock *sk, struct proto *p,
> >
> >         ctx = tls_get_ctx(sk);
> >         if (likely(ctx)) {
> > +               /* TLS does not have an unhash proto in SW cases, but we need
> > +                * to ensure we stop using the sock_map unhash routine because
> > +                * the associated psock is being removed. So use the original
> > +                * unhash handler.
> > +                */
> > +               WRITE_ONCE(sk->sk_prot->unhash, p->unhash);
> >                 ctx->sk_write_space = write_space;
> >                 ctx->sk_proto = p;
> 
> It looks awkward to update sk->sk_proto inside tls_update(),
> at least when ctx!=NULL.

hmm. It doesn't strike me as paticularly awkward but OK.

> 
> What is wrong with updating it in sk_psock_restore_proto()
> when inet_csk_has_ulp() is true? It looks better to me.

It could be wrong if inet_csk_has_ulp has an unhash callback
already assigned. But, because we know inet_csk_has_ulp()
really means is_tls_attached() it would be fine.

> 
> diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
> index 6c09d94be2e9..da5dc3ef0ee3 100644
> --- a/include/linux/skmsg.h
> +++ b/include/linux/skmsg.h
> @@ -360,8 +360,8 @@ static inline void sk_psock_update_proto(struct sock *sk,
>  static inline void sk_psock_restore_proto(struct sock *sk,
>                                           struct sk_psock *psock)
>  {
> -       sk->sk_prot->unhash = psock->saved_unhash;
>         if (inet_csk_has_ulp(sk)) {
> +               sk->sk_prot->unhash = psock->sk_proto->unhash;
>                 tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
>         } else {
>                 sk->sk_write_space = psock->saved_write_space;
> 
> 
> sk_psock_restore_proto() is the only caller of tcp_update_ulp()
> so should be equivalent.

Agree it is equivalent. I don't mind moving the assignment around
if folks think its nicer.

> 
> Thanks.