From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yuchung Cheng Subject: Re: [PATCH v2 net-next] tcp: Enable TFO without a cookie on a per-socket basis Date: Fri, 20 Oct 2017 17:46:06 -0700 Message-ID: References: <20171020211303.76466-1-cpaasch@apple.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Cc: David Miller , netdev , Eric Dumazet To: Christoph Paasch Return-path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:52265 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753002AbdJUAqt (ORCPT ); Fri, 20 Oct 2017 20:46:49 -0400 Received: by mail-wm0-f66.google.com with SMTP id k4so703579wmc.1 for ; Fri, 20 Oct 2017 17:46:48 -0700 (PDT) In-Reply-To: <20171020211303.76466-1-cpaasch@apple.com> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, Oct 20, 2017 at 2:13 PM, Christoph Paasch wrote: > > We already allow to enable TFO without a cookie by using the > fastopen-sysctl and setting it to TFO_SERVER_COOKIE_NOT_REQD (0x200). > This is safe to do in certain environments where we know that there > isn't a malicous host (aka., data-centers). > > A server however might be talking to both sides (public Internet and > data-center). So, this server would want to enable cookie-less TFO for > the connections that go to the data-center while enforcing cookies for > the traffic from the Internet. > > This patch exposes a socket-option to enable this (protected by > CAP_NET_ADMIN). the protection is removed in this version? > > Signed-off-by: Christoph Paasch > --- > > Notes: > v2: * Rename to fastopen_no_cookie and TCP_FASTOPEN_NO_COOKIE > * Add per-route attribute for fastopen_no_cookie > * Get rid of the capability check > > include/linux/tcp.h | 3 ++- > include/net/tcp.h | 3 ++- > include/uapi/linux/rtnetlink.h | 2 ++ > include/uapi/linux/tcp.h | 1 + > net/ipv4/tcp.c | 12 ++++++++++++ > net/ipv4/tcp_fastopen.c | 14 +++++++++++--- > net/ipv4/tcp_input.c | 2 +- > 7 files changed, 31 insertions(+), 6 deletions(-) > > diff --git a/include/linux/tcp.h b/include/linux/tcp.h > index 1d2c44e09e31..173a7c2f9636 100644 > --- a/include/linux/tcp.h > +++ b/include/linux/tcp.h > @@ -215,7 +215,8 @@ struct tcp_sock { > u8 chrono_type:2, /* current chronograph type */ > rate_app_limited:1, /* rate_{delivered,interval_us} limited? */ > fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */ > - unused:4; > + fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */ > + unused:3; > u8 nonagle : 4,/* Disable Nagle algorithm? */ > thin_lto : 1,/* Use linear timeouts for thin streams */ > unused1 : 1, > diff --git a/include/net/tcp.h b/include/net/tcp.h > index 1efe8365cb28..020b20c3f50a 100644 > --- a/include/net/tcp.h > +++ b/include/net/tcp.h > @@ -1562,7 +1562,8 @@ int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk, > void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); > struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, > struct request_sock *req, > - struct tcp_fastopen_cookie *foc); > + struct tcp_fastopen_cookie *foc, > + const struct dst_entry *dst); > void tcp_fastopen_init_key_once(struct net *net); > bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, > struct tcp_fastopen_cookie *cookie); > diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h > index dab7dad9e01a..fe6679268901 100644 > --- a/include/uapi/linux/rtnetlink.h > +++ b/include/uapi/linux/rtnetlink.h > @@ -430,6 +430,8 @@ enum { > #define RTAX_QUICKACK RTAX_QUICKACK > RTAX_CC_ALGO, > #define RTAX_CC_ALGO RTAX_CC_ALGO > + RTAX_FASTOPEN_NO_COOKIE, > +#define RTAX_FASTOPEN_NO_COOKIE RTAX_FASTOPEN_NO_COOKIE > __RTAX_MAX > }; > > diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h > index 69c7493e42f8..d67e1d40c6d6 100644 > --- a/include/uapi/linux/tcp.h > +++ b/include/uapi/linux/tcp.h > @@ -120,6 +120,7 @@ enum { > #define TCP_ULP 31 /* Attach a ULP to a TCP connection */ > #define TCP_MD5SIG_EXT 32 /* TCP MD5 Signature with extensions */ > #define TCP_FASTOPEN_KEY 33 /* Set the key for Fast Open (cookie) */ > +#define TCP_FASTOPEN_NO_COOKIE 34 /* Enable TFO without a TFO cookie */ > > struct tcp_repair_opt { > __u32 opt_code; > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c > index 8b1fa4dd4538..a3d46a781abd 100644 > --- a/net/ipv4/tcp.c > +++ b/net/ipv4/tcp.c > @@ -2832,6 +2832,14 @@ static int do_tcp_setsockopt(struct sock *sk, int level, > err = -EOPNOTSUPP; > } > break; > + case TCP_FASTOPEN_NO_COOKIE: > + if (val > 1 || val < 0) > + err = -EINVAL; > + else if (!((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) > + err = -EINVAL; > + else > + tp->fastopen_no_cookie = 1; > + break; > case TCP_TIMESTAMP: > if (!tp->repair) > err = -EPERM; > @@ -3252,6 +3260,10 @@ static int do_tcp_getsockopt(struct sock *sk, int level, > val = tp->fastopen_connect; > break; > > + case TCP_FASTOPEN_NO_COOKIE: > + val = tp->fastopen_no_cookie; > + break; > + > case TCP_TIMESTAMP: > val = tcp_time_stamp_raw() + tp->tsoffset; > break; > diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c > index 21075ce19cb6..e704bd86fdf9 100644 > --- a/net/ipv4/tcp_fastopen.c > +++ b/net/ipv4/tcp_fastopen.c > @@ -316,7 +316,8 @@ static bool tcp_fastopen_queue_check(struct sock *sk) > */ > struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, > struct request_sock *req, > - struct tcp_fastopen_cookie *foc) > + struct tcp_fastopen_cookie *foc, > + const struct dst_entry *dst) > { > bool syn_data = TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1; > int tcp_fastopen = sock_net(sk)->ipv4.sysctl_tcp_fastopen; > @@ -333,7 +334,9 @@ struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, > return NULL; > } > > - if (syn_data && (tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD)) > + if (syn_data && ((tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD) || > + tcp_sk(sk)->fastopen_no_cookie || > + (dst && dst_metric(dst, RTAX_FASTOPEN_NO_COOKIE)))) > goto fastopen; > > if (foc->len >= 0 && /* Client presents or requests a cookie */ > @@ -370,6 +373,7 @@ bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, > struct tcp_fastopen_cookie *cookie) > { > unsigned long last_syn_loss = 0; > + const struct dst_entry *dst; > int syn_loss = 0; > > tcp_fastopen_cache_get(sk, mss, cookie, &syn_loss, &last_syn_loss); > @@ -387,7 +391,11 @@ bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, > return false; > } > > - if (sock_net(sk)->ipv4.sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) { > + dst = __sk_dst_get(sk); > + > + if ((sock_net(sk)->ipv4.sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) || > + tcp_sk(sk)->fastopen_no_cookie || > + (dst && dst_metric(dst, RTAX_FASTOPEN_NO_COOKIE))) { perhaps a helper e.g. tcp_fastopen_needs_cookie(syscl_flag) for this function and tcp_try_fastopen() to tidy the code a bit? > cookie->len = -1; > return true; > } > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c > index b2390bfdc68f..a6cf6407f780 100644 > --- a/net/ipv4/tcp_input.c > +++ b/net/ipv4/tcp_input.c > @@ -6329,7 +6329,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, > tcp_openreq_init_rwin(req, sk, dst); > if (!want_cookie) { > tcp_reqsk_record_syn(sk, req, skb); > - fastopen_sk = tcp_try_fastopen(sk, skb, req, &foc); > + fastopen_sk = tcp_try_fastopen(sk, skb, req, &foc, dst); > } > if (fastopen_sk) { > af_ops->send_synack(fastopen_sk, dst, &fl, req, > -- > 2.14.1 >