From patchwork Tue Jul 26 06:15:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leonard Crestez X-Patchwork-Id: 12928663 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 BCCE7C43334 for ; Tue, 26 Jul 2022 06:16:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237752AbiGZGQm (ORCPT ); Tue, 26 Jul 2022 02:16:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57416 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237683AbiGZGQ1 (ORCPT ); Tue, 26 Jul 2022 02:16:27 -0400 Received: from mail-ej1-x62f.google.com (mail-ej1-x62f.google.com [IPv6:2a00:1450:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BDC90BF4A; Mon, 25 Jul 2022 23:15:52 -0700 (PDT) Received: by mail-ej1-x62f.google.com with SMTP id mf4so24384682ejc.3; Mon, 25 Jul 2022 23:15:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=3A89M6f/ZAUek7dxYg8vkPNRORGAYIO7TwHRAva/jSw=; b=mEkE6nG04vVrPwFDujbZsT/7OvjuWtFcW4BEwOs3bm/DKWGJdhmvt3iipqL35vObWb eIsY9zZen6XVoM5WQUYxXhNoX2DnR8SRUeSoSgjhdLtGmT4zAuZvNHQyz4VR0oBq6An8 ZmgHs6mL4giyi0GH7ZD1fL/DmZI930YGiaN/A7pt5y7xIXEx44jAYUmECSsGsq4+HJ87 bOQdMEtjPY6PgY6Oa1Cd4a8qotxYKhH5aEbfU5uzc76mCUjrnWvuXL5ukrvVczUUh4AW 37b3sXqog15PjMBYE/0+ktHOokT0JWDCaUy/xf6BDY9NIGYmH9LjafBkEEdjl6QjWcDH EgXw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=3A89M6f/ZAUek7dxYg8vkPNRORGAYIO7TwHRAva/jSw=; b=U94V63V1bP0MJfBMpwDUQ1c3GQGvmp1f7XbqUTSlRemh9Yx3lXk+rZ6MdX5sccjM4i zavHcFJEF4C79ES2a29RzDfTVzRsWf49tFbxmPcrtQIuLYRfylOZU0b8UAyRGPiVQ7MC 2NSuXM8uXRja3nxLBvIGoDaISFmJH2Qpj6ktHc4hJXQxGkH/U0XxPgwcdTnrtprxJJYY OqZN5qm9Yg66at/y/gt2/hSA6wKdo0QsbpiuE4WDnf3Pl4PFgLw/Q+VV8jnlTI0nXcEw mOMU/+iQbeSR3Fpdp21O5RTLmrvGTfjk+bKEMUJ9KzNaRfSGwiliwUHH/4qvr0awNjWO GGAA== X-Gm-Message-State: AJIora+fiKCZXMTyZzw4HabqMneMGtAVjpxbX6/XphfY8NyZyPgJ7Oqh flPsQB8TT0d6YA7YBtnk7sA= X-Google-Smtp-Source: AGRyM1t6dUaXs7cEK7p1Vv3yLm+utwnP1P6VInHIQ2li/10pnCZnbrzNfeF7xrqhfUHhAyOUWIHlFQ== X-Received: by 2002:a17:907:a426:b0:72e:faf6:2873 with SMTP id sg38-20020a170907a42600b0072efaf62873mr12933458ejc.74.1658816151154; Mon, 25 Jul 2022 23:15:51 -0700 (PDT) Received: from localhost.localdomain ([2a04:241e:502:a080:2b68:36a:5a94:4ba1]) by smtp.gmail.com with ESMTPSA id l23-20020a056402345700b0043ba7df7a42sm8133067edc.26.2022.07.25.23.15.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jul 2022 23:15:50 -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 v6 07/26] tcp: Refactor tcp_inbound_md5_hash into tcp_inbound_sig_hash Date: Tue, 26 Jul 2022 09:15:09 +0300 Message-Id: <69a18af444691e88217ee13e20fa5f796c3834ff.1658815925.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 | 37 ++++++++++++++++++++-------- net/ipv4/tcp_ipv4.c | 12 +++++----- net/ipv6/tcp_ipv6.c | 8 +++---- 6 files changed, 113 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 793e8802fef0..b107ee5ab108 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, @@ -1683,32 +1705,19 @@ 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); @@ -1721,10 +1730,25 @@ 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 4cdc34200bcf..3b950768cbaf 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -4528,24 +4528,24 @@ 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]; @@ -4554,11 +4554,10 @@ 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; @@ -4592,14 +4591,44 @@ 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 ae73b34d32e9..a7ac580a65c7 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4184,43 +4184,60 @@ 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 5c13d3460ce1..93c564022748 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 16e85ae4f029..12f63ce66bcc 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;