From patchwork Thu Aug 18 19:59:40 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leonard Crestez X-Patchwork-Id: 12947760 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 A504FC32772 for ; Thu, 18 Aug 2022 20:00:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345689AbiHRUAy (ORCPT ); Thu, 18 Aug 2022 16:00:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345280AbiHRUAa (ORCPT ); Thu, 18 Aug 2022 16:00:30 -0400 Received: from mail-ed1-x52d.google.com (mail-ed1-x52d.google.com [IPv6:2a00:1450:4864:20::52d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3BB80D11C6; Thu, 18 Aug 2022 13:00:29 -0700 (PDT) Received: by mail-ed1-x52d.google.com with SMTP id w3so3217138edc.2; Thu, 18 Aug 2022 13:00:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc; bh=lst4jYQoWqW22J7+IkYDuwssupI9FP63jPAToNOVsvc=; b=ROWSk0/XdwyIBT4fnj9tgFmokvehPRJyhCYqfsA5FjjQ4lY/C8Cqlsco+9uMf6If9A hCeurLETrgwEzxlKXSNPKTn8e8755sdPDF1edvoZdxI+pzMrMp0GLI+WOAM8G+5zYiD5 mbe/L6mMgJT+0adneN5dMzd6+w5ywv2ZxsZIfm1HdJdc7NGxNUEzu2pY+0LHgeUFnLbz kx56CTNLCMDW3A5lXywBqaZpDbWbOnPobMJFHyNZhuRzJ+4Am12lUiT81fVVt8W8/qh4 u/EtKFQAfXnJYFolUnb1tvjSdSfVPvub9itP4sV3C4A77ZlTOyvDiRFsOtyTwtJiN4j6 y9+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc; bh=lst4jYQoWqW22J7+IkYDuwssupI9FP63jPAToNOVsvc=; b=7EM07HaMC5Ubh/uHfbqbNb9Ir8Uf/K9B+6t5uU3NqPfS3uAHCZYgb8PqozbAKvChNx 3E4G7h837enQ3EM4fno94by4cIZuvcNK1FvaOAD0xwN7zDOdeUfykC1DmFSwjewDFfyA ppusg8BK83aaMu/M4W8Xyxu0EpOWarFZWjBfS/NrISpLGJZ5mAjFCUP5VCDv9vOvIFHL XuQWSjicWfFvaOHm6HDu2hlCFSGpfZYScb7wlOUAB5sLvYFpYy0d2KlMMGEXAAMCDH12 qoa+IK4tTufKzjq01Za29RLz/EFV32qD422TkD7LdZlLR9UNEUqZ1xIo/o2NNOySETqc pkmg== X-Gm-Message-State: ACgBeo0jl7wq+OFnLaunoLS9zklJL2ABevhFVO0cFOjJnY53Gb4iisq4 6hps2awn/zPBA6jc9cfth7E= X-Google-Smtp-Source: AA6agR7CEBfGHkUfSEOyYXwlLOwZXSuJgvgi+VXeAKk8rbhESZ0HGFDK8awj1TmAlyrq9YWsvotjxw== X-Received: by 2002:a05:6402:26cb:b0:43e:6fab:11c6 with SMTP id x11-20020a05640226cb00b0043e6fab11c6mr3328293edd.272.1660852827694; Thu, 18 Aug 2022 13:00:27 -0700 (PDT) Received: from localhost.localdomain ([2a04:241e:502:a080:17c8:ba1c:b6f3:3fe0]) by smtp.gmail.com with ESMTPSA id fw30-20020a170907501e00b00722e4bab163sm1215087ejc.200.2022.08.18.13.00.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Aug 2022 13:00:27 -0700 (PDT) From: Leonard Crestez To: David Ahern , Eric Dumazet , Philip Paeps Cc: Dmitry Safonov <0x7f454c46@gmail.com>, Shuah Khan , "David S. Miller" , Herbert Xu , Kuniyuki Iwashima , Hideaki YOSHIFUJI , Jakub Kicinski , Yuchung Cheng , Francesco Ruggeri , Mat Martineau , Christoph Paasch , Ivan Delalande , Caowangbao , Priyaranjan Jha , netdev@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v7 06/26] tcp: Refactor tcp_inbound_md5_hash into tcp_inbound_sig_hash Date: Thu, 18 Aug 2022 22:59:40 +0300 Message-Id: <42b7fa32c0fca77abb1e6a234f2dac45798f605b.1660852705.git.cdleonard@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org The TCP-MD5 and TCP-AO signature options must be handled together so replace the old tcp_inbound_md5_hash with tcp_inbound_sig_hash which will handle both options. As a side effect of this change Linux will start dropping packets where both MD5 and AO are present instead of ignoring the so-far unrecognized AO option. This is a direct requirement from RFC5925 2.2 This difference can be detected remotely without ever establishing a connection and used to fingerprint linux version. This seems acceptable. Signed-off-by: Leonard Crestez --- include/net/dropreason.h | 4 ++++ include/net/tcp.h | 52 +++++++++++++++++++++++++++++----------- net/ipv4/tcp.c | 39 ++++++++++++++++++++++++++---- net/ipv4/tcp_input.c | 39 ++++++++++++++++++++++-------- net/ipv4/tcp_ipv4.c | 12 +++++----- net/ipv6/tcp_ipv6.c | 8 +++---- 6 files changed, 115 insertions(+), 39 deletions(-) diff --git a/include/net/dropreason.h b/include/net/dropreason.h index fae9b40e54fa..c5397c24296c 100644 --- a/include/net/dropreason.h +++ b/include/net/dropreason.h @@ -229,10 +229,14 @@ enum skb_drop_reason { /** * @SKB_DROP_REASON_PKT_TOO_BIG: packet size is too big (maybe exceed the * MTU) */ SKB_DROP_REASON_PKT_TOO_BIG, + /** + * @SKB_DROP_REASON_TCP_BOTHAOMD5: Both AO and MD5 found in packet. + */ + SKB_DROP_REASON_TCP_BOTHAOMD5, /** * @SKB_DROP_REASON_MAX: the maximum of drop reason, which shouldn't be * used as a real 'reason' */ SKB_DROP_REASON_MAX, diff --git a/include/net/tcp.h b/include/net/tcp.h index fbe18b5bf576..96e7e406e324 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -424,11 +424,33 @@ int tcp_mmap(struct file *file, struct socket *sock, struct vm_area_struct *vma); #endif void tcp_parse_options(const struct net *net, const struct sk_buff *skb, struct tcp_options_received *opt_rx, int estab, struct tcp_fastopen_cookie *foc); -const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); +#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AUTHOPT) +enum skb_drop_reason tcp_parse_sig_options(const struct tcphdr *th, + const u8 **md5ptr, + const u8 **aoptr); +#else +static inline enum skb_drop_reason tcp_parse_sig_options(const struct tcphdr *th, + const u8 **md5ptr, + const u8 **aoptr) +{ + *aoptr = NULL; + *md5ptr = NULL; + return 0; +} +#endif +static inline const u8 *tcp_parse_md5sig_option(const struct tcphdr *th) +{ + const u8 *md5, *ao; + int ret; + + ret = tcp_parse_sig_options(th, &md5, &ao); + + return (md5 && !ao && !ret) ? md5 : NULL; +} /* * BPF SKB-less helpers */ u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph, @@ -1685,32 +1707,19 @@ tcp_md5_do_lookup(const struct sock *sk, int l3index, if (!static_branch_unlikely(&tcp_md5_needed)) return NULL; return __tcp_md5_do_lookup(sk, l3index, addr, family); } -enum skb_drop_reason -tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb, - const void *saddr, const void *daddr, - int family, int dif, int sdif); - - #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) #else static inline struct tcp_md5sig_key * tcp_md5_do_lookup(const struct sock *sk, int l3index, const union tcp_md5_addr *addr, int family) { return NULL; } -static inline enum skb_drop_reason -tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb, - const void *saddr, const void *daddr, - int family, int dif, int sdif) -{ - return SKB_NOT_DROPPED_YET; -} #define tcp_twsk_md5_key(twsk) NULL #endif bool tcp_alloc_md5sig_pool(void); @@ -1723,10 +1732,25 @@ static inline void tcp_put_md5sig_pool(void) int tcp_sig_hash_skb_data(struct ahash_request *, const struct sk_buff *, unsigned int header_len); int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *key); +#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AUTHOPT) +enum skb_drop_reason +tcp_inbound_sig_hash(const struct sock *sk, const struct sk_buff *skb, + const void *saddr, const void *daddr, + int family, int dif, int sdif); +#else +static inline enum skb_drop_reason +tcp_inbound_sig_hash(const struct sock *sk, const struct sk_buff *skb, + const void *saddr, const void *daddr, + int family, int dif, int sdif) +{ + return SKB_NOT_DROPPED_YET; +} +#endif + /* From tcp_fastopen.c */ void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, struct tcp_fastopen_cookie *cookie); void tcp_fastopen_cache_set(struct sock *sk, u16 mss, struct tcp_fastopen_cookie *cookie, bool syn_lost, diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 4c61c32ccf49..0611a2160b63 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -4568,24 +4568,24 @@ int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *ke return data_race(crypto_ahash_update(hp->md5_req)); } EXPORT_SYMBOL(tcp_md5_hash_key); /* Called with rcu_read_lock() */ -enum skb_drop_reason +static enum skb_drop_reason tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb, const void *saddr, const void *daddr, - int family, int dif, int sdif) + int family, int dif, int sdif, + const u8 *hash_location) { /* * This gets called for each TCP segment that arrives * so we want to be efficient. * We have 3 drop cases: * o No MD5 hash and one expected. * o MD5 hash and we're not expecting one. * o MD5 hash and its wrong. */ - const __u8 *hash_location = NULL; struct tcp_md5sig_key *hash_expected; const struct tcphdr *th = tcp_hdr(skb); struct tcp_sock *tp = tcp_sk(sk); int genhash, l3index; u8 newhash[16]; @@ -4594,11 +4594,10 @@ tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb, * in an L3 domain and dif is set to the l3mdev */ l3index = sdif ? dif : 0; hash_expected = tcp_md5_do_lookup(sk, l3index, saddr, family); - hash_location = tcp_parse_md5sig_option(th); /* We've parsed the options - do we have a hash? */ if (!hash_expected && !hash_location) return SKB_NOT_DROPPED_YET; @@ -4641,14 +4640,44 @@ tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb, } return SKB_DROP_REASON_TCP_MD5FAILURE; } return SKB_NOT_DROPPED_YET; } -EXPORT_SYMBOL(tcp_inbound_md5_hash); #endif /* CONFIG_TCP_MD5SIG */ +#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AUTHOPT) + +enum skb_drop_reason +tcp_inbound_sig_hash(const struct sock *sk, const struct sk_buff *skb, + const void *saddr, const void *daddr, + int family, int dif, int sdif) +{ + /* FIXME: Restore reqsk handling */ + const u8 *md5, *ao; + enum skb_drop_reason ret; + const struct sock *parent_sk; + + if (sk->sk_state == TCP_NEW_SYN_RECV) + parent_sk = inet_reqsk(sk)->rsk_listener; + else + parent_sk = sk; + + ret = tcp_parse_sig_options(tcp_hdr(skb), &md5, &ao); + if (ret) + return ret; + +#ifdef CONFIG_TCP_MD5SIG + return tcp_inbound_md5_hash(parent_sk, skb, saddr, daddr, family, dif, sdif, md5); +#else + return SKB_NOT_DROPPED_YET; +#endif +} +EXPORT_SYMBOL(tcp_inbound_sig_hash); + +#endif /* defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AUTHOPT) */ + void tcp_done(struct sock *sk) { struct request_sock *req; /* We might be called with a new socket, after diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index ab5f0ea166f1..fa20afd15248 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4186,43 +4186,62 @@ static bool tcp_fast_parse_options(const struct net *net, tp->rx_opt.rcv_tsecr -= tp->tsoffset; return true; } -#ifdef CONFIG_TCP_MD5SIG +#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AUTHOPT) /* - * Parse MD5 Signature option + * Parse MD5 and AO options + * + * md5ptr: pointer to content of MD5 option (16-byte hash) + * aoptr: pointer to start of AO option (variable length) */ -const u8 *tcp_parse_md5sig_option(const struct tcphdr *th) +enum skb_drop_reason tcp_parse_sig_options(const struct tcphdr *th, + const u8 **md5ptr, + const u8 **aoptr) { int length = (th->doff << 2) - sizeof(*th); const u8 *ptr = (const u8 *)(th + 1); + *md5ptr = NULL; + *aoptr = NULL; + /* If not enough data remaining, we can short cut */ - while (length >= TCPOLEN_MD5SIG) { + while (length >= 4) { int opcode = *ptr++; int opsize; switch (opcode) { case TCPOPT_EOL: - return NULL; + goto out; case TCPOPT_NOP: length--; continue; default: opsize = *ptr++; if (opsize < 2 || opsize > length) - return NULL; - if (opcode == TCPOPT_MD5SIG) - return opsize == TCPOLEN_MD5SIG ? ptr : NULL; + goto out; + if (opcode == TCPOPT_MD5SIG && opsize == TCPOLEN_MD5SIG) + *md5ptr = ptr; + if (opcode == TCPOPT_AUTHOPT) + *aoptr = ptr - 2; } ptr += opsize - 2; length -= opsize; } - return NULL; + +out: + /* RFC5925 2.2: An endpoint MUST NOT use TCP-AO for the same connection + * in which TCP MD5 is used. When both options appear, TCP MUST silently + * discard the segment. + */ + if (*md5ptr && *aoptr) + return SKB_DROP_REASON_TCP_BOTHAOMD5; + + return SKB_NOT_DROPPED_YET; } -EXPORT_SYMBOL(tcp_parse_md5sig_option); +EXPORT_SYMBOL(tcp_parse_sig_options); #endif /* Sorry, PAWS as specified is broken wrt. pure-ACKs -DaveM * * It is not fatal. If this ACK does _not_ change critical state (seqs, window) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 46ba754afd2b..58b5f197bde1 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1964,17 +1964,17 @@ int tcp_v4_rcv(struct sk_buff *skb) if (sk->sk_state == TCP_NEW_SYN_RECV) { struct request_sock *req = inet_reqsk(sk); bool req_stolen = false; struct sock *nsk; - sk = req->rsk_listener; - if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) + if (!xfrm4_policy_check(req->rsk_listener, XFRM_POLICY_IN, skb)) drop_reason = SKB_DROP_REASON_XFRM_POLICY; else - drop_reason = tcp_inbound_md5_hash(sk, skb, - &iph->saddr, &iph->daddr, - AF_INET, dif, sdif); + drop_reason = tcp_inbound_sig_hash(sk, skb, + &iph->saddr, &iph->daddr, + AF_INET, dif, sdif); + sk = req->rsk_listener; if (unlikely(drop_reason)) { sk_drops_add(sk, skb); reqsk_put(req); goto discard_it; } @@ -2046,11 +2046,11 @@ int tcp_v4_rcv(struct sk_buff *skb) if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) { drop_reason = SKB_DROP_REASON_XFRM_POLICY; goto discard_and_relse; } - drop_reason = tcp_inbound_md5_hash(sk, skb, &iph->saddr, + drop_reason = tcp_inbound_sig_hash(sk, skb, &iph->saddr, &iph->daddr, AF_INET, dif, sdif); if (drop_reason) goto discard_and_relse; nf_reset_ct(skb); diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 30dc9d4eec83..2edfe631878e 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1632,14 +1632,14 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) if (sk->sk_state == TCP_NEW_SYN_RECV) { struct request_sock *req = inet_reqsk(sk); bool req_stolen = false; struct sock *nsk; - sk = req->rsk_listener; - drop_reason = tcp_inbound_md5_hash(sk, skb, + drop_reason = tcp_inbound_sig_hash(sk, skb, &hdr->saddr, &hdr->daddr, AF_INET6, dif, sdif); + sk = req->rsk_listener; if (drop_reason) { sk_drops_add(sk, skb); reqsk_put(req); goto discard_it; } @@ -1707,12 +1707,12 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) { drop_reason = SKB_DROP_REASON_XFRM_POLICY; goto discard_and_relse; } - drop_reason = tcp_inbound_md5_hash(sk, skb, &hdr->saddr, &hdr->daddr, - AF_INET6, dif, sdif); + drop_reason = tcp_inbound_sig_hash(sk, skb, &hdr->saddr, + &hdr->daddr, AF_INET6, dif, sdif); if (drop_reason) goto discard_and_relse; if (tcp_filter(sk, skb)) { drop_reason = SKB_DROP_REASON_SOCKET_FILTER;