From nobody Wed Feb 11 19:42:39 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB837CA0EC3 for ; Tue, 12 Sep 2023 02:29:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237556AbjILC3P (ORCPT ); Mon, 11 Sep 2023 22:29:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58634 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230011AbjILC3D (ORCPT ); Mon, 11 Sep 2023 22:29:03 -0400 Received: from mail-lf1-x12f.google.com (mail-lf1-x12f.google.com [IPv6:2a00:1450:4864:20::12f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E92DE1178D8 for ; Mon, 11 Sep 2023 17:16:32 -0700 (PDT) Received: by mail-lf1-x12f.google.com with SMTP id 2adb3069b0e04-500760b296aso6098487e87.0 for ; Mon, 11 Sep 2023 17:16:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=google; t=1694477715; x=1695082515; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=euMSph5qkkhRT404htxzpvv3O/y2v2RbFYhwpUx0x+c=; b=LOqoGKOVqQEQsP+eP46rYEx+puIvqZFZuCf1iKP1haDoHokwcPwvIW0HDgQIUSby5f YlsGNLA2fOq8E45KNBdIDZPyQ80nuDI/kaOhxLWuY46J5rDr0fyqRhMoKFhPOBRnorbB FKO81OmcxMz0fTfH74QNOi0rg3HvXKUqOHUyMItLbRs0ssYRQlE2FsMGWIkfQBbrBnLO CDhMwYH7h7GH4BQSzvbvCw09LnFcE7qK04JpGnBZCNtkOvOyRKivsrUlPbPxt02Tk4XL JFTUe99k7AJrgBoOgiFpXG4Gug5eADlqEXL6RlUNvz4bv/62XtfCm3rKayG6gM0YVoSu BaXA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694477715; x=1695082515; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=euMSph5qkkhRT404htxzpvv3O/y2v2RbFYhwpUx0x+c=; b=J2PUTuU4GVxn0DOj4h7F8eCZnORd2PSKI5cSbAC5ga3yVR4dsHFzl4faAlXKvw9GMf RXQRdWK6MdQJDFdPbvv/8h5Mg4hAHToyYlC21o6k0H5l0gZSDJEki4YQVM7sXXFWxv10 TDVwWF+TsHrLG4ADqj0GS7PevCvZ4x5udX70c3z0pQ5ytJaRWMTYRGCxsz/UvBVlHALa 9eslqGJ2NoSSRJoTQt3F46PvHyXhdFSpZ0g5O1nWIRVXyi6bt5azHYmk5c/ak0ok8LYc S+loYcmGJAqO8eqkNEoZ6jrCBT12QGom09rjuoAVKClfIavi+xtLLN5qtR+7eYB2Eerv ZWTw== X-Gm-Message-State: AOJu0YzMINKOJkM49xNzxcZrD/y4PfrnHYLZSJ/hvz5Z7kTA2hF181FA 4Kw6NFroR8d42aIdG4bj4hr0pk6XyY2rkwbmduI= X-Google-Smtp-Source: AGHT+IEjQjst3JdzowDOIq3CkDmeCWw8xWG3+3Ee2LrCws9t49LoXU4NLc9tmWoo4MhvMMxWR7YLPA== X-Received: by 2002:a05:600c:4e50:b0:401:b393:da18 with SMTP id e16-20020a05600c4e5000b00401b393da18mr481696wmq.6.1694466264653; Mon, 11 Sep 2023 14:04:24 -0700 (PDT) Received: from Mindolluin.ire.aristanetworks.com ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id z20-20020a1c4c14000000b00402e942561fsm14261699wmf.38.2023.09.11.14.04.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Sep 2023 14:04:24 -0700 (PDT) From: Dmitry Safonov To: David Ahern , Eric Dumazet , Paolo Abeni , Jakub Kicinski , "David S. Miller" Cc: linux-kernel@vger.kernel.org, Dmitry Safonov , Andy Lutomirski , Ard Biesheuvel , Bob Gilligan , Dan Carpenter , David Laight , Dmitry Safonov <0x7f454c46@gmail.com>, Donald Cassidy , Eric Biggers , "Eric W. Biederman" , Francesco Ruggeri , "Gaillardetz, Dominik" , Herbert Xu , Hideaki YOSHIFUJI , Ivan Delalande , Leonard Crestez , "Nassiri, Mohammad" , Salam Noureddine , Simon Horman , "Tetreault, Francois" , netdev@vger.kernel.org Subject: [PATCH v11 net-next 16/23] net/tcp: Ignore specific ICMPs for TCP-AO connections Date: Mon, 11 Sep 2023 22:03:36 +0100 Message-ID: <20230911210346.301750-17-dima@arista.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230911210346.301750-1-dima@arista.com> References: <20230911210346.301750-1-dima@arista.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Similarly to IPsec, RFC5925 prescribes: ">> A TCP-AO implementation MUST default to ignore incoming ICMPv4 messages of Type 3 (destination unreachable), Codes 2-4 (protocol unreachable, port unreachable, and fragmentation needed -- =E2=80=99hard errors=E2=80=99), and ICMPv6 Type 1 (destination unreachable), Code 1 (administratively prohibited) and Code 4 (port unreachable) intended for connections in synchronized states (ESTABLISHED, FIN-WAIT-1, FIN- WAIT-2, CLOSE-WAIT, CLOSING, LAST-ACK, TIME-WAIT) that match MKTs." A selftest (later in patch series) verifies that this attack is not possible in this TCP-AO implementation. Co-developed-by: Francesco Ruggeri Signed-off-by: Francesco Ruggeri Co-developed-by: Salam Noureddine Signed-off-by: Salam Noureddine Signed-off-by: Dmitry Safonov Acked-by: David Ahern --- include/net/tcp_ao.h | 10 ++++++- include/uapi/linux/snmp.h | 1 + include/uapi/linux/tcp.h | 4 ++- net/ipv4/proc.c | 1 + net/ipv4/tcp_ao.c | 58 +++++++++++++++++++++++++++++++++++++++ net/ipv4/tcp_ipv4.c | 7 +++++ net/ipv6/tcp_ipv6.c | 7 +++++ 7 files changed, 86 insertions(+), 2 deletions(-) diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h index 5c5d16b6f9f9..4c290c647272 100644 --- a/include/net/tcp_ao.h +++ b/include/net/tcp_ao.h @@ -24,6 +24,7 @@ struct tcp_ao_counters { atomic64_t pkt_bad; atomic64_t key_not_found; atomic64_t ao_required; + atomic64_t dropped_icmp; }; =20 struct tcp_ao_key { @@ -92,7 +93,8 @@ struct tcp_ao_info { struct tcp_ao_key *rnext_key; struct tcp_ao_counters counters; u32 ao_required :1, - __unused :31; + accept_icmps :1, + __unused :30; __be32 lisn; __be32 risn; /* Sequence Number Extension (SNE) are upper 4 bytes for SEQ, @@ -189,6 +191,7 @@ int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 = *key, void *ctx, unsigned int len, struct tcp_sigpool *hp); void tcp_ao_destroy_sock(struct sock *sk, bool twsk); void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw, struct tcp_sock *tp= ); +bool tcp_ao_ignore_icmp(const struct sock *sk, int type, int code); enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb, unsigned short int family, const struct request_sock *req, @@ -264,6 +267,11 @@ static inline void tcp_ao_syncookie(struct sock *sk, c= onst struct sk_buff *skb, { } =20 +static inline bool tcp_ao_ignore_icmp(const struct sock *sk, int type, int= code) +{ + return false; +} + static inline enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb, unsigned short int family, const struct request_sock *req, const struct tcp_ao_hdr *aoh) diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h index 06ddf4cd295c..47a6b47da66f 100644 --- a/include/uapi/linux/snmp.h +++ b/include/uapi/linux/snmp.h @@ -300,6 +300,7 @@ enum LINUX_MIB_TCPAOBAD, /* TCPAOBad */ LINUX_MIB_TCPAOKEYNOTFOUND, /* TCPAOKeyNotFound */ LINUX_MIB_TCPAOGOOD, /* TCPAOGood */ + LINUX_MIB_TCPAODROPPEDICMPS, /* TCPAODroppedIcmps */ __LINUX_MIB_MAX }; =20 diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h index 3fe0612ec59a..ca7ed18ce67b 100644 --- a/include/uapi/linux/tcp.h +++ b/include/uapi/linux/tcp.h @@ -392,7 +392,8 @@ struct tcp_ao_info_opt { /* setsockopt(TCP_AO_INFO) */ set_rnext :1, /* corresponding ::rnext */ ao_required :1, /* don't accept non-AO connects */ set_counters :1, /* set/clear ::pkt_* counters */ - reserved :28; /* must be 0 */ + accept_icmps :1, /* accept incoming ICMPs */ + reserved :27; /* must be 0 */ __u16 reserved2; /* padding, must be 0 */ __u8 current_key; /* KeyID to set as Current_key */ __u8 rnext; /* KeyID to set as Rnext_key */ @@ -400,6 +401,7 @@ struct tcp_ao_info_opt { /* setsockopt(TCP_AO_INFO) */ __u64 pkt_bad; /* failed verification */ __u64 pkt_key_not_found; /* could not find a key to verify */ __u64 pkt_ao_required; /* segments missing TCP-AO sign */ + __u64 pkt_dropped_icmp; /* ICMPs that were ignored */ } __attribute__((aligned(8))); =20 /* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */ diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c index 3f643cd29cfe..5d3c9c96773e 100644 --- a/net/ipv4/proc.c +++ b/net/ipv4/proc.c @@ -302,6 +302,7 @@ static const struct snmp_mib snmp4_net_list[] =3D { SNMP_MIB_ITEM("TCPAOBad", LINUX_MIB_TCPAOBAD), SNMP_MIB_ITEM("TCPAOKeyNotFound", LINUX_MIB_TCPAOKEYNOTFOUND), SNMP_MIB_ITEM("TCPAOGood", LINUX_MIB_TCPAOGOOD), + SNMP_MIB_ITEM("TCPAODroppedIcmps", LINUX_MIB_TCPAODROPPEDICMPS), SNMP_MIB_SENTINEL }; =20 diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c index 2283203f1ac5..a8af93972ee5 100644 --- a/net/ipv4/tcp_ao.c +++ b/net/ipv4/tcp_ao.c @@ -15,6 +15,7 @@ =20 #include #include +#include =20 int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx, unsigned int len, struct tcp_sigpool *hp) @@ -44,6 +45,60 @@ int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *= key, void *ctx, return 1; } =20 +bool tcp_ao_ignore_icmp(const struct sock *sk, int type, int code) +{ + bool ignore_icmp =3D false; + struct tcp_ao_info *ao; + + /* RFC5925, 7.8: + * >> A TCP-AO implementation MUST default to ignore incoming ICMPv4 + * messages of Type 3 (destination unreachable), Codes 2-4 (protocol + * unreachable, port unreachable, and fragmentation needed -- =E2=80=99ha= rd + * errors=E2=80=99), and ICMPv6 Type 1 (destination unreachable), Code 1 + * (administratively prohibited) and Code 4 (port unreachable) intended + * for connections in synchronized states (ESTABLISHED, FIN-WAIT-1, FIN- + * WAIT-2, CLOSE-WAIT, CLOSING, LAST-ACK, TIME-WAIT) that match MKTs. + */ + if (sk->sk_family =3D=3D AF_INET) { + if (type !=3D ICMP_DEST_UNREACH) + return false; + if (code < ICMP_PROT_UNREACH || code > ICMP_FRAG_NEEDED) + return false; + } else { + if (type !=3D ICMPV6_DEST_UNREACH) + return false; + if (code !=3D ICMPV6_ADM_PROHIBITED && code !=3D ICMPV6_PORT_UNREACH) + return false; + } + + rcu_read_lock(); + switch (sk->sk_state) { + case TCP_TIME_WAIT: + ao =3D rcu_dereference(tcp_twsk(sk)->ao_info); + break; + case TCP_SYN_SENT: + case TCP_SYN_RECV: + case TCP_LISTEN: + case TCP_NEW_SYN_RECV: + /* RFC5925 specifies to ignore ICMPs *only* on connections + * in synchronized states. + */ + rcu_read_unlock(); + return false; + default: + ao =3D rcu_dereference(tcp_sk(sk)->ao_info); + } + + if (ao && !ao->accept_icmps) { + ignore_icmp =3D true; + __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAODROPPEDICMPS); + atomic64_inc(&ao->counters.dropped_icmp); + } + rcu_read_unlock(); + + return ignore_icmp; +} + /* Optimized version of tcp_ao_do_lookup(): only for sockets for which * it's known that the keys in ao_info are matching peer's * family/address/VRF/etc. @@ -1035,6 +1090,7 @@ int tcp_ao_copy_all_matching(const struct sock *sk, s= truct sock *newsk, new_ao->lisn =3D htonl(tcp_rsk(req)->snt_isn); new_ao->risn =3D htonl(tcp_rsk(req)->rcv_isn); new_ao->ao_required =3D ao->ao_required; + new_ao->accept_icmps =3D ao->accept_icmps; =20 if (family =3D=3D AF_INET) { addr =3D (union tcp_ao_addr *)&newsk->sk_daddr; @@ -1741,9 +1797,11 @@ static int tcp_ao_info_cmd(struct sock *sk, unsigned= short int family, atomic64_set(&ao_info->counters.pkt_bad, cmd.pkt_bad); atomic64_set(&ao_info->counters.key_not_found, cmd.pkt_key_not_found); atomic64_set(&ao_info->counters.ao_required, cmd.pkt_ao_required); + atomic64_set(&ao_info->counters.dropped_icmp, cmd.pkt_dropped_icmp); } =20 ao_info->ao_required =3D cmd.ao_required; + ao_info->accept_icmps =3D cmd.accept_icmps; if (new_current) WRITE_ONCE(ao_info->current_key, new_current); if (new_rnext) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 0f702b33fdef..a4aef27b0f72 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -493,6 +493,8 @@ int tcp_v4_err(struct sk_buff *skb, u32 info) return -ENOENT; } if (sk->sk_state =3D=3D TCP_TIME_WAIT) { + /* To increase the counter of ignored icmps for TCP-AO */ + tcp_ao_ignore_icmp(sk, type, code); inet_twsk_put(inet_twsk(sk)); return 0; } @@ -506,6 +508,11 @@ int tcp_v4_err(struct sk_buff *skb, u32 info) return 0; } =20 + if (tcp_ao_ignore_icmp(sk, type, code)) { + sock_put(sk); + return 0; + } + bh_lock_sock(sk); /* If too many ICMPs get dropped on busy * servers this needs to be solved differently. diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 59719c8bc5ac..60c2129890ec 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -395,6 +395,8 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6= _skb_parm *opt, } =20 if (sk->sk_state =3D=3D TCP_TIME_WAIT) { + /* To increase the counter of ignored icmps for TCP-AO */ + tcp_ao_ignore_icmp(sk, type, code); inet_twsk_put(inet_twsk(sk)); return 0; } @@ -405,6 +407,11 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet= 6_skb_parm *opt, return 0; } =20 + if (tcp_ao_ignore_icmp(sk, type, code)) { + sock_put(sk); + return 0; + } + bh_lock_sock(sk); if (sock_owned_by_user(sk) && type !=3D ICMPV6_PKT_TOOBIG) __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); --=20 2.41.0