From mboxrd@z Thu Jan 1 00:00:00 1970 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 212BF13FF9 for ; Tue, 8 Aug 2023 16:28:14 +0000 (UTC) Received: from mail-il1-x12a.google.com (mail-il1-x12a.google.com [IPv6:2607:f8b0:4864:20::12a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1291A893F for ; Tue, 8 Aug 2023 09:27:55 -0700 (PDT) Received: by mail-il1-x12a.google.com with SMTP id e9e14a558f8ab-3493d0f785dso152245ab.1 for ; Tue, 08 Aug 2023 09:27:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1691512015; x=1692116815; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=GyES+4AF5nitte7BPshvVJ/M/14djHeZo3yws6zb9Z8=; b=Ju8gsRwzOdOsWJXQBpoulXpTXvs8TWdhBemV8EXRHs6V0CYeaN8iQ6SgiDmfpc51oL U6pSikus1KjwlTZEEIM536oHFNwarz0arGcRXHdkhzitNYWqmpHcq5HvRBHN00lnKKAs yGKY/GLf5FP2EWvdr6NEGaY6xpCG9fzkCDphPIDgXxaDIbw8VjuDTtghwr6e7rLiORqh wNvn/q2M+9ueVOgqA9r5YIhgVQyS7fWLkAhN9DKi6z9kizObkyWZsjH3MgIAMzAhHC9i fxNLpMwhaD0vdjcK5Cci1Pcwf+hNvbaKW46b/3irDTxO3kwCJs3x7k+qSMZRJ0s7j1zu gBNw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691512015; x=1692116815; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=GyES+4AF5nitte7BPshvVJ/M/14djHeZo3yws6zb9Z8=; b=Z3QFZGBy7Fpbcbf8NJ0BFDAD9SnPQf/DR1cI7iqYtFRyz3so24gDKmvcimZ40jcHgl fUs8mK97JhNVksxtnKC2mNLcbpCfbrEPL3OuUpE+s7wICRnDvMYAEEpR39BnFUWDKRd4 LueHoz2UYolU9dFd8enR5lFwGICv7UsvUqB/5j39TzlRzHfLHKkUL9w+/IvkPE3K6RHp 0LT4XS/69rDQCBlSRcuTicPBYX+vZgSNqFB4dLlqCQM76sTNFGPXrln0o4a9kYu2nNdu fWJWMkAC11KWB0CCASNyLJm3QZyOym2D70NraTkcfkrTD1DFp/q0QsDRgWxvCClPh3c4 JoUQ== X-Gm-Message-State: AOJu0YwI3xzpit+qiEPghhzAXW/AwbmB5onW+HkJ2QGwoP/dTJ27rpcj +KPnsg22cfTaZCFhOoJcnlwmMj9++8/RKmMWpCJBtm3Mjt5DAoNwjnOK/Q== X-Google-Smtp-Source: AGHT+IHc9vm7JbEPlckcKoimq6rV3JrGtLsAkpCo98NFPRTR+rWv/NXfBb6AidjtdAp6Ci1rTqmNQCaXGL7gXYK71ww= X-Received: by 2002:a05:622a:40b:b0:3f9:56c:1129 with SMTP id n11-20020a05622a040b00b003f9056c1129mr777271qtx.5.1691502249315; Tue, 08 Aug 2023 06:44:09 -0700 (PDT) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20230802172654.1467777-1-dima@arista.com> <20230802172654.1467777-17-dima@arista.com> In-Reply-To: <20230802172654.1467777-17-dima@arista.com> From: Eric Dumazet Date: Tue, 8 Aug 2023 15:43:57 +0200 Message-ID: Subject: Re: [PATCH v9 net-next 16/23] net/tcp: Ignore specific ICMPs for TCP-AO connections To: Dmitry Safonov Cc: David Ahern , Paolo Abeni , Jakub Kicinski , "David S. Miller" , linux-kernel@vger.kernel.org, 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-17.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, ENV_AND_HDR_SPF_MATCH,RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL,USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Wed, Aug 2, 2023 at 7:27=E2=80=AFPM Dmitry Safonov wro= te: > > 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=99har= d > 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 | 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 986e8dcbb150..94fde002b638 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 { > @@ -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, u= 8 *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 fam= ily, > const struct request_sock *req, > @@ -264,6 +267,11 @@ 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 cod= e) > +{ > + 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[] =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 > }; > > diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c > index 226dcefb426a..236c8cd1a0c7 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) const struct sock *sk ? > +{ > + bool ignore_icmp =3D false; > + struct tcp_ao_info *ao; > + > + /* RFC5925, 7.8: > + * >> A TCP-AO implementation MUST default to ignore incoming ICM= Pv4 > + * messages of Type 3 (destination unreachable), Codes 2-4 (proto= col > + * 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) in= tended > + * for connections in synchronized states (ESTABLISHED, FIN-WAIT-= 1, FIN- > + * WAIT-2, CLOSE-WAIT, CLOSING, LAST-ACK, TIME-WAIT) that match M= KTs. > + */ I know this sounds silly, but you should read sk->sk_family once. Or risk another KCSAN report with IPV6_ADDRFORM if (sk->sk_family =3D=3D AF_INET) { ... } else { /* AF_INET case */ } > + 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 (sk->sk_family =3D=3D AF_INET6) { > + if (type !=3D ICMPV6_DEST_UNREACH) > + return false; > + if (code !=3D ICMPV6_ADM_PROHIBITED && code !=3D ICMPV6_P= ORT_UNREACH) > + return false; > + } else { No WARN_ON_ONCE(1) here please. > + WARN_ON_ONCE(1); > + 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 connection= s > + * 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. > @@ -1036,6 +1094,7 @@ int tcp_ao_copy_all_matching(const struct sock *sk,= struct 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; > > if (family =3D=3D AF_INET) { > addr =3D (union tcp_ao_addr *)&newsk->sk_daddr; > @@ -1742,9 +1801,11 @@ static int tcp_ao_info_cmd(struct sock *sk, unsign= ed short int family, > atomic64_set(&ao_info->counters.pkt_bad, cmd.pkt_bad); > atomic64_set(&ao_info->counters.key_not_found, cmd.pkt_ke= y_not_found); > atomic64_set(&ao_info->counters.ao_required, cmd.pkt_ao_r= equired); > + atomic64_set(&ao_info->counters.dropped_icmp, cmd.pkt_dro= pped_icmp); > } > > 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 42a3be6c25a4..ae910181693d 100644 > --- a/net/ipv4/tcp_ipv4.c > +++ b/net/ipv4/tcp_ipv4.c > @@ -494,6 +494,8 @@ 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; > } > @@ -508,6 +510,9 @@ int tcp_v4_err(struct sk_buff *skb, u32 info) > } > > bh_lock_sock(sk); Do we need to hold the spinlock before calling tcp_ao_ignore_icmp() ? > + 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 f1804ec3bb1d..07126d9eeda9 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 ine= t6_skb_parm *opt, > } > > 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; > } > @@ -406,6 +408,8 @@ static int tcp_v6_err(struct sk_buff *skb, struct ine= t6_skb_parm *opt, > } > > bh_lock_sock(sk); > + if (tcp_ao_ignore_icmp(sk, type, code)) > + goto out; > if (sock_owned_by_user(sk) && type !=3D ICMPV6_PKT_TOOBIG) > __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); > > -- > 2.41.0 >