From nobody Thu Jul 25 20:57:13 2024 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4WVNVd1qJZz5RHfC; Thu, 25 Jul 2024 20:57:13 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R11" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4WVNVd15frz4D1f; Thu, 25 Jul 2024 20:57:13 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1721941033; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=nWzH+YXw3SD9IGOx38HpTxO7WJ1ebBgos3Wt/C1sl1c=; b=c0I/T+lQzmbu7hs7JrbcqUKHfNKUh/i07kmJNSW/wtgxavPoHen7qADva5ktSx1aVtneMK YB3fmoPpVkCZ0hrR8lgV2dkqoRDdemWnFF6Q0/Auz5J4Z0vX0gaJjXZlQQyEBO7YW8/LZ9 VTCLGJYcUrIVoH2E4p9l55w6HBlrBaEei8fcgPBm4inibyVMmjMT057K1x8cwkSUzC8G7Q NacJR9S9KAeUpzkblyBW0PQARqIuys2HpcA5K1X5tZpl1N5nVu/qmUWwRDRmup7Mqe1PuY /fAYcDKWj38/Jh1cMusSMh3SHYISuvfNZk4VoT/hbBTf3sZ4RdJURN/Qeu2Obw== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1721941033; a=rsa-sha256; cv=none; b=bYKB9sh/yJ4ygD0swwXQFpAvXgOlCKg6uga7gtzyj1jLzgz6VOtUuwFo3eV76G1EPNEU/M SEQgQYces5GkbJABdpXC5JY/nJFyK4qZMm9Y9JB1G9OXy9GbaDjnvoyrQAuIOgG2tKJurw 9kYkqRNyccjn/mQc8k8AYYQQ3I8k0M6pPOXwyvtannHwhOLsy45jbPnmizCPEmDvwirBQS 3mnxEzDLfunYudZ2wj77UlEpiBrb1Tl0qUYTQlgCiBVZyRdBmAreDb8wIk0JCXticjzVM3 tyNO96d0iFJFKd68HBxJisb/6a1wDRGStrsyxhwgCNOvyvWRmvMj0jVYkGQJMg== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1721941033; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=nWzH+YXw3SD9IGOx38HpTxO7WJ1ebBgos3Wt/C1sl1c=; b=ENVXgx+U1NWktZbibEmgx9sRFkM2hoj9qgXZngFZVE0kc8sbZpBsJcIe4FpCmqvrQyr1YK 36T73YENNQuShL9qDeageNUDtzsoc0LjtImv8GHErToIOPn1aDtS2R3b/2VSKX/+vcyBPS O0u9xUIa+PbUqSl0WxCrwNXzgLwQL5iSpCn2+vOZBNvOmitz1ol3FEj7EI7R0IWl4lqYOW gRG42Nh2C8D7UbDLZONbW8K/rQu5j2fetsqY/dSVVkAhfeYIRAGbr1UHnpj4zH5fRoJVxH ym3yF+CJTTKqPsrCCrExAWDCk2XJMB0mrhBwoAzcwmyB45hfm+GyyIA2YoI+2g== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4WVNVd0j0cz19L0; Thu, 25 Jul 2024 20:57:13 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.18.1/8.18.1) with ESMTP id 46PKvDxl077771; Thu, 25 Jul 2024 20:57:13 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.18.1/8.18.1/Submit) id 46PKvD5J077768; Thu, 25 Jul 2024 20:57:13 GMT (envelope-from git) Date: Thu, 25 Jul 2024 20:57:13 GMT Message-Id: <202407252057.46PKvD5J077768@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Michael Tuexen Subject: git: 40299c55a05f - main - tcp: implement challenge ACK throttling for the base stack List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-all@freebsd.org Sender: owner-dev-commits-src-all@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: tuexen X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: 40299c55a05ff008102e24269d5f2d7fa7b6842d Auto-Submitted: auto-generated The branch main has been updated by tuexen: URL: https://cgit.FreeBSD.org/src/commit/?id=40299c55a05ff008102e24269d5f2d7fa7b6842d commit 40299c55a05ff008102e24269d5f2d7fa7b6842d Author: Michael Tuexen AuthorDate: 2024-07-25 11:54:52 +0000 Commit: Michael Tuexen CommitDate: 2024-07-25 11:54:52 +0000 tcp: implement challenge ACK throttling for the base stack Implement ACK throttling of challenge ACKs as described in RFC 5961. Reviewed by: Peter Lei, rscheff, cc MFC after: 1 week Sponsored by: Netflix, Inc. Differential Revision: https://reviews.freebsd.org/D46066 --- sys/netinet/tcp_input.c | 15 +++------------ sys/netinet/tcp_subr.c | 39 +++++++++++++++++++++++++++++++++++++++ sys/netinet/tcp_var.h | 6 ++++++ 3 files changed, 48 insertions(+), 12 deletions(-) diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c index ad17a9fdfb93..b64a71837ab4 100644 --- a/sys/netinet/tcp_input.c +++ b/sys/netinet/tcp_input.c @@ -2208,10 +2208,7 @@ tcp_do_segment(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th, } } else { TCPSTAT_INC(tcps_badrst); - /* Send challenge ACK. */ - tcp_respond(tp, mtod(m, void *), th, m, - tp->rcv_nxt, tp->snd_nxt, TH_ACK); - tp->last_ack_sent = tp->rcv_nxt; + tcp_send_challenge_ack(tp, th, m); m = NULL; } } @@ -2233,10 +2230,7 @@ tcp_do_segment(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th, rstreason = BANDLIM_UNLIMITED; } else { tcp_ecn_input_syn_sent(tp, thflags, iptos); - /* Send challenge ACK. */ - tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, - tp->snd_nxt, TH_ACK); - tp->last_ack_sent = tp->rcv_nxt; + tcp_send_challenge_ack(tp, th, m); m = NULL; } goto drop; @@ -2474,10 +2468,7 @@ tcp_do_segment(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th, TCPSTAT_INC(tcps_rcvghostack); else TCPSTAT_INC(tcps_rcvacktooold); - /* Send a challenge ACK. */ - tcp_respond(tp, mtod(m, void *), th, m, - tp->rcv_nxt, tp->snd_nxt, TH_ACK); - tp->last_ack_sent = tp->rcv_nxt; + tcp_send_challenge_ack(tp, th, m); m = NULL; goto drop; } diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c index 42d29d64e09f..0665564955d2 100644 --- a/sys/netinet/tcp_subr.c +++ b/sys/netinet/tcp_subr.c @@ -2181,6 +2181,45 @@ tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m, lgb->tlb_errno = output_ret; } +/* + * Send a challenge ack (no data, no SACK option), but not more than + * tcp_ack_war_cnt per tcp_ack_war_time_window (per TCP connection). + */ +void +tcp_send_challenge_ack(struct tcpcb *tp, struct tcphdr *th, struct mbuf *m) +{ + sbintime_t now; + bool send_challenge_ack; + + if (tcp_ack_war_time_window == 0 || tcp_ack_war_cnt == 0) { + /* ACK war protection is disabled. */ + send_challenge_ack = true; + } else { + /* Start new epoch, if the previous one is already over. */ + now = getsbinuptime(); + if (tp->t_challenge_ack_end < now) { + tp->t_challenge_ack_cnt = 0; + tp->t_challenge_ack_end = now + + tcp_ack_war_time_window * SBT_1MS; + } + /* + * Send a challenge ACK, if less than tcp_ack_war_cnt have been + * sent in the current epoch. + */ + if (tp->t_challenge_ack_cnt < tcp_ack_war_cnt) { + send_challenge_ack = true; + tp->t_challenge_ack_cnt++; + } else { + send_challenge_ack = false; + } + } + if (send_challenge_ack) { + tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, + tp->snd_nxt, TH_ACK); + tp->last_ack_sent = tp->rcv_nxt; + } +} + /* * Create a new TCP control block, making an empty reassembly queue and hooking * it to the argument protocol control block. The `inp' parameter must have diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h index c06efa601a81..af82d0bfeaaa 100644 --- a/sys/netinet/tcp_var.h +++ b/sys/netinet/tcp_var.h @@ -465,6 +465,11 @@ struct tcpcb { /* TCP Fast Open */ uint8_t t_tfo_client_cookie_len; /* TFO client cookie length */ uint32_t t_end_info_status; /* Status flag of end info */ + sbintime_t t_challenge_ack_end; /* End of the challenge ack epoch */ + uint32_t t_challenge_ack_cnt; /* Number of challenge ACKs sent in + * current epoch + */ + unsigned int *t_tfo_pending; /* TFO server pending counter */ union { uint8_t client[TCP_FASTOPEN_MAX_COOKIE_LEN]; @@ -1460,6 +1465,7 @@ int tcp_default_output(struct tcpcb *); void tcp_state_change(struct tcpcb *, int); void tcp_respond(struct tcpcb *, void *, struct tcphdr *, struct mbuf *, tcp_seq, tcp_seq, uint16_t); +void tcp_send_challenge_ack(struct tcpcb *, struct tcphdr *, struct mbuf *); bool tcp_twcheck(struct inpcb *, struct tcpopt *, struct tcphdr *, struct mbuf *, int); void tcp_setpersist(struct tcpcb *);