From patchwork Wed Jul 19 20:26:21 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Dmitry Safonov X-Patchwork-Id: 13319482 X-Patchwork-Delegate: kuba@kernel.org Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A17D622EF4 for ; Wed, 19 Jul 2023 20:27:32 +0000 (UTC) Received: from mail-wm1-x32a.google.com (mail-wm1-x32a.google.com [IPv6:2a00:1450:4864:20::32a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD791270B for ; Wed, 19 Jul 2023 13:27:07 -0700 (PDT) Received: by mail-wm1-x32a.google.com with SMTP id 5b1f17b1804b1-3fbc54cab6fso382725e9.0 for ; Wed, 19 Jul 2023 13:27:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=google; t=1689798426; x=1692390426; 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=mRXwfghTgFYkZUWtm2C85v3QLVstDk1mJ1X3wx92FjE=; b=DMylN3k+NX8K7pi6ty6N1YrqXtNqyXrbJGPoqpm7u63pS2lZq9dAQKoIVCEsatJGl4 101XCUFiPJ40EzJ5aoMH8IyBMPhl/jrsJzZr4myV4l/O+46p7U3IJQaw1AlWEj8vAzJp DuPhJUOIj0JLg7SSPxZM07hGEFRZT3fQugSs1uYKCEQWM3AvNrm/WkyH65iQnYgMVwcA j0mK6L7IiKyoMhvvsKsqjbDojC8/xRa1q3a77h46ijNlQ4I3BbO5Na3f76G5LzFcaQJ+ RV1JfFRthv9IDW+lgJDPnaNfuB4AnBtdBcvv3Nx6uoiAWDIvEtb+U3GXh4mIZnv92KaA n4dg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689798426; x=1692390426; 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=mRXwfghTgFYkZUWtm2C85v3QLVstDk1mJ1X3wx92FjE=; b=f6d/WW4z08PKs4ByPH5iiFKVHDPf8Fyejb+KDiLrO6hDx4HIQ+RYvfb1KsEcHVTNmj TV0k8HPsT/DmBovhJiRMqPDmngTgxo+qI7qXXIVpbzihMSa7ZXF7DO2SQnW8O9xVexqg aIW1ELpT7j3lIl4lQpwYT7LXgNQ3M0nvorUH/0Ux1GVqTYocPKcVPkYh5HE77eOoRLg2 Snxd3d3rToZdWPiOjGlDRoO0m2JKEn5mR013WEG2qjtxVg49b38KhlJjIUb4MHQKupvQ d7A8UKwToY2tsKkHagigraeEdRZ2GREl+nrUbmqI+MnakvoIsYnx32mIXarSYFT57jTU cuFA== X-Gm-Message-State: ABy/qLaO4evkJJPI3XF13YM2V6VtMgdKrD1BxHjb6H/i5YnQzlYam3OR e5H+LeAGGKp1R81ptiue1iMn6A== X-Google-Smtp-Source: APBJJlEla7JSeFzzJeJzfA5ZTEwjS7rpDA7itYTiTyzrHxsg4OYYO5XUk30O4zZ9dSUEGEOknv2Rsg== X-Received: by 2002:a05:600c:2947:b0:3fb:ac9c:e6f with SMTP id n7-20020a05600c294700b003fbac9c0e6fmr318109wmd.38.1689798425751; Wed, 19 Jul 2023 13:27:05 -0700 (PDT) Received: from Mindolluin.ire.aristanetworks.com ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id 3-20020a05600c234300b003fc04d13242sm2432319wmq.0.2023.07.19.13.27.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Jul 2023 13:27:05 -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 , Salam Noureddine , "Tetreault, Francois" , netdev@vger.kernel.org Subject: [PATCH v8 16/23] net/tcp: Ignore specific ICMPs for TCP-AO connections Date: Wed, 19 Jul 2023 21:26:21 +0100 Message-ID: <20230719202631.472019-17-dima@arista.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230719202631.472019-1-dima@arista.com> References: <20230719202631.472019-1-dima@arista.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: kuba@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 -- ’hard errors’), 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 --- 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 | 61 +++++++++++++++++++++++++++++++++++++++ net/ipv4/tcp_ipv4.c | 5 ++++ net/ipv6/tcp_ipv6.c | 4 +++ 7 files changed, 84 insertions(+), 2 deletions(-) diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h index 801dca405df7..cb16af2a9f39 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; }; struct tcp_ao_key { @@ -93,7 +94,8 @@ 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, @@ -188,6 +190,7 @@ 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(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, @@ -266,6 +269,11 @@ static inline void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb, { } +static inline bool tcp_ao_ignore_icmp(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 }; 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))); /* 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[] = { 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 }; diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c index 9ee7fc9f6a76..4bde58ede63a 100644 --- a/net/ipv4/tcp_ao.c +++ b/net/ipv4/tcp_ao.c @@ -15,6 +15,7 @@ #include #include +#include int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx, unsigned int len, struct tcp_sigpool *hp) @@ -44,6 +45,63 @@ int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx, return 1; } +bool tcp_ao_ignore_icmp(struct sock *sk, int type, int code) +{ + struct tcp_ao_info *ao; + bool ignore_icmp = false; + + /* 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 -- ’hard + * errors’), 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 == AF_INET) { + if (type != ICMP_DEST_UNREACH) + return false; + if (code < ICMP_PROT_UNREACH || code > ICMP_FRAG_NEEDED) + return false; + } else if (sk->sk_family == AF_INET6) { + if (type != ICMPV6_DEST_UNREACH) + return false; + if (code != ICMPV6_ADM_PROHIBITED && code != ICMPV6_PORT_UNREACH) + return false; + } else { + WARN_ON_ONCE(1); + return false; + } + + rcu_read_lock(); + switch (sk->sk_state) { + case TCP_TIME_WAIT: + ao = 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 = rcu_dereference(tcp_sk(sk)->ao_info); + } + + if (ao && !ao->accept_icmps) { + ignore_icmp = 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/port/VRF/etc. @@ -1044,6 +1102,7 @@ int tcp_ao_copy_all_matching(const struct sock *sk, struct sock *newsk, new_ao->lisn = htonl(tcp_rsk(req)->snt_isn); new_ao->risn = htonl(tcp_rsk(req)->rcv_isn); new_ao->ao_required = ao->ao_required; + new_ao->accept_icmps = ao->accept_icmps; if (family == AF_INET) { addr = (union tcp_ao_addr *)&newsk->sk_daddr; @@ -1764,9 +1823,11 @@ 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); } ao_info->ao_required = cmd.ao_required; + ao_info->accept_icmps = 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 1b53c4bd37ed..6cb282e0197c 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -492,6 +492,8 @@ int tcp_v4_err(struct sk_buff *skb, u32 info) return -ENOENT; } if (sk->sk_state == 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 +508,9 @@ int tcp_v4_err(struct sk_buff *skb, u32 info) } bh_lock_sock(sk); + if (tcp_ao_ignore_icmp(sk, type, code)) + goto out; + /* If too many ICMPs get dropped on busy * servers this needs to be solved differently. * We do take care of PMTU discovery (RFC1191) special case : diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index a666e8bab9d9..0adcd7faea08 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, } if (sk->sk_state == 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; } @@ -406,6 +408,8 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, } bh_lock_sock(sk); + if (tcp_ao_ignore_icmp(sk, type, code)) + goto out; if (sock_owned_by_user(sk) && type != ICMPV6_PKT_TOOBIG) __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);