From patchwork Mon Sep 5 07:05:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leonard Crestez X-Patchwork-Id: 12965590 X-Patchwork-Delegate: kuba@kernel.org 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 34A6AC6FA91 for ; Mon, 5 Sep 2022 07:07:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237286AbiIEHHb (ORCPT ); Mon, 5 Sep 2022 03:07:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46428 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237084AbiIEHGc (ORCPT ); Mon, 5 Sep 2022 03:06:32 -0400 Received: from mail-ej1-x631.google.com (mail-ej1-x631.google.com [IPv6:2a00:1450:4864:20::631]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E0A423F1F5; Mon, 5 Sep 2022 00:06:27 -0700 (PDT) Received: by mail-ej1-x631.google.com with SMTP id nc14so15128368ejc.4; Mon, 05 Sep 2022 00:06:27 -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:subject:date; bh=9rF3YSJc7bXDmqpfKkrhBZzvU5UvoIG4YushIn8blt4=; b=OuTGf9cJ+acYi7RyiguQc11gIw3gipW+7eqdRAGmPZ19BP1+yo0eVx9OwHW44yMCsX p1U0IyTbKxfei7fQcndo8HbHF6YU2bwiYBpC88T7ywEMy6TjY1qgyQ1Ji3qdsFe8Ng4g SaIMclyjDoOve/hXwgZFGUZNSjfMec32nSWuX1PxlnAec6Cct9qtP3IhcxOmmKwlaeG4 rzUd8C3afkCIqJgPnuARX+V746yzx2fyU7ncW+d/2pqTMF1f0FAqbvsvFXWaSGimzH5L oshgx1CQdCP4S3JIOZskk0I5FC2y/PFCFSeVU93ICCVmybl0LDHJyaSvJRHk5gitTqu7 Ai4g== 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 :subject:date; bh=9rF3YSJc7bXDmqpfKkrhBZzvU5UvoIG4YushIn8blt4=; b=Dg1xVkcH3MDBgeqLCoE9CFe7Jai7P0y8ZORD3ytwuWxAAM9da97bGH9I991MeYUx2x H9/I9aUd7Q5bttPpm20rRPDOwYYUsuXoZlFKIlq1y9OihLEx+c7IdyvTFAaLXV7pvKzb XESKmahUIbzxQWh/i82qKQgJ/mYCivVRn84iSGYMgLf5RSWJ8Ljvov+z5XieZS3HCQdO EwTKlDdVeTFd84+k5qzMagbSNqFCMvqLurYtlDbUrxY7M4ZJQ+xieWdhHbFfIwcTcbLL jbaVyuDGBTv5KCQlzkVkAwu5pjukacoatUlJNMI30E8fEeudCpqqE6JTSkifVEhylUb6 1GTA== X-Gm-Message-State: ACgBeo0lEqFUPhDkxlcJW1Izu3JPQJAr7OsPfJagCtzS9qTjwq6Ut3ij dV275H9sRd1eHHu/CMeitkY= X-Google-Smtp-Source: AA6agR4xFkV7rEoP/OsXwoLTGKpCbh7LKy816jeN71z5+rgNvr+OL2dtnW1fPEFFGDiP3tUhG3U+LQ== X-Received: by 2002:a17:907:7d91:b0:731:7ecb:1e5b with SMTP id oz17-20020a1709077d9100b007317ecb1e5bmr34788829ejc.78.1662361586494; Mon, 05 Sep 2022 00:06:26 -0700 (PDT) Received: from localhost.localdomain ([2a04:241e:502:a080:40ec:9f50:387:3cfb]) by smtp.gmail.com with ESMTPSA id n27-20020a056402515b00b0043cf2e0ce1csm5882775edd.48.2022.09.05.00.06.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Sep 2022 00:06:26 -0700 (PDT) From: Leonard Crestez To: David Ahern , Eric Dumazet , Dmitry Safonov <0x7f454c46@gmail.com> Cc: Francesco Ruggeri , Salam Noureddine , Philip Paeps , Shuah Khan , "David S. Miller" , Herbert Xu , Kuniyuki Iwashima , Hideaki YOSHIFUJI , Jakub Kicinski , Yuchung Cheng , 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 v8 08/26] tcp: authopt: Disable via sysctl by default Date: Mon, 5 Sep 2022 10:05:44 +0300 Message-Id: <298e4e87ce3a822b4217b309438483959082e6bb.1662361354.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: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org This is mainly intended to protect against local privilege escalations through a rarely used feature so it is deliberately not namespaced. Enforcement is only at the setsockopt level, this should be enough to ensure that the tcp_authopt_needed static key never turns on. No effort is made to handle disabling when the feature is already in use. Signed-off-by: Leonard Crestez --- Documentation/networking/ip-sysctl.rst | 6 ++++ include/net/tcp_authopt.h | 1 + net/ipv4/sysctl_net_ipv4.c | 39 ++++++++++++++++++++++++++ net/ipv4/tcp_authopt.c | 25 +++++++++++++++++ 4 files changed, 71 insertions(+) diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index a759872a2883..41be0e69d767 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -1038,10 +1038,16 @@ tcp_challenge_ack_limit - INTEGER Note that this per netns rate limit can allow some side channel attacks and probably should not be enabled. TCP stack implements per TCP socket limits anyway. Default: INT_MAX (unlimited) +tcp_authopt - BOOLEAN + Enable the TCP Authentication Option (RFC5925), a replacement for TCP + MD5 Signatures (RFC2835). + + Default: 0 + UDP variables ============= udp_l3mdev_accept - BOOLEAN Enabling this option allows a "global" bound socket to work diff --git a/include/net/tcp_authopt.h b/include/net/tcp_authopt.h index 7ad34a6987ec..1f5020b790dd 100644 --- a/include/net/tcp_authopt.h +++ b/include/net/tcp_authopt.h @@ -80,10 +80,11 @@ struct tcphdr_authopt { }; #ifdef CONFIG_TCP_AUTHOPT DECLARE_STATIC_KEY_FALSE(tcp_authopt_needed_key); #define tcp_authopt_needed (static_branch_unlikely(&tcp_authopt_needed_key)) +extern int sysctl_tcp_authopt; void tcp_authopt_free(struct sock *sk, struct tcp_authopt_info *info); void tcp_authopt_clear(struct sock *sk); int tcp_set_authopt(struct sock *sk, sockptr_t optval, unsigned int optlen); int tcp_get_authopt_val(struct sock *sk, struct tcp_authopt *key); int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen); diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 5490c285668b..908a3ef15b47 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -17,10 +17,11 @@ #include #include #include #include #include +#include static int tcp_retr1_max = 255; static int ip_local_port_range_min[] = { 1, 1 }; static int ip_local_port_range_max[] = { 65535, 65535 }; static int tcp_adv_win_scale_min = -31; @@ -413,10 +414,37 @@ static int proc_fib_multipath_hash_fields(struct ctl_table *table, int write, return ret; } #endif +#ifdef CONFIG_TCP_AUTHOPT +static int proc_tcp_authopt(struct ctl_table *ctl, + int write, void *buffer, size_t *lenp, + loff_t *ppos) +{ + int val = sysctl_tcp_authopt; + struct ctl_table tmp = { + .data = &val, + .mode = ctl->mode, + .maxlen = sizeof(val), + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }; + int err; + + err = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); + if (err) + return err; + if (sysctl_tcp_authopt && !val) { + net_warn_ratelimited("Enabling TCP Authentication Option is permanent\n"); + return -EINVAL; + } + sysctl_tcp_authopt = val; + return 0; +} +#endif + static struct ctl_table ipv4_table[] = { { .procname = "tcp_max_orphans", .data = &sysctl_tcp_max_orphans, .maxlen = sizeof(int), @@ -524,10 +552,21 @@ static struct ctl_table ipv4_table[] = { .mode = 0644, .proc_handler = proc_douintvec_minmax, .extra1 = &sysctl_fib_sync_mem_min, .extra2 = &sysctl_fib_sync_mem_max, }, +#ifdef CONFIG_TCP_AUTHOPT + { + .procname = "tcp_authopt", + .data = &sysctl_tcp_authopt, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_tcp_authopt, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, +#endif { } }; static struct ctl_table ipv4_net_table[] = { /* tcp_max_tw_buckets must be first in this table. */ diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c index 4f7cbe1e17f3..9d02da8d6964 100644 --- a/net/ipv4/tcp_authopt.c +++ b/net/ipv4/tcp_authopt.c @@ -4,10 +4,15 @@ #include #include #include #include +/* This is mainly intended to protect against local privilege escalations through + * a rarely used feature so it is deliberately not namespaced. + */ +int sysctl_tcp_authopt; + /* This is enabled when first struct tcp_authopt_info is allocated and never released */ DEFINE_STATIC_KEY_FALSE(tcp_authopt_needed_key); EXPORT_SYMBOL(tcp_authopt_needed_key); /* All current algorithms have a mac length of 12 but crypto API digestsize can be larger */ @@ -437,17 +442,30 @@ static int _copy_from_sockptr_tolerant(u8 *dst, memset(dst + srclen, 0, dstlen - srclen); return err; } +static int check_sysctl_tcp_authopt(void) +{ + if (!sysctl_tcp_authopt) { + net_warn_ratelimited("TCP Authentication Option disabled by sysctl.\n"); + return -EPERM; + } + + return 0; +} + int tcp_set_authopt(struct sock *sk, sockptr_t optval, unsigned int optlen) { struct tcp_authopt opt; struct tcp_authopt_info *info; int err; sock_owned_by_me(sk); + err = check_sysctl_tcp_authopt(); + if (err) + return err; err = _copy_from_sockptr_tolerant((u8 *)&opt, sizeof(opt), optval, optlen); if (err) return err; @@ -465,13 +483,17 @@ int tcp_set_authopt(struct sock *sk, sockptr_t optval, unsigned int optlen) int tcp_get_authopt_val(struct sock *sk, struct tcp_authopt *opt) { struct tcp_sock *tp = tcp_sk(sk); struct tcp_authopt_info *info; + int err; memset(opt, 0, sizeof(*opt)); sock_owned_by_me(sk); + err = check_sysctl_tcp_authopt(); + if (err) + return err; info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk)); if (!info) return -ENOENT; @@ -493,10 +515,13 @@ int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen) struct netns_tcp_authopt *net = sock_net_tcp_authopt(sk); struct tcp_authopt_alg_imp *alg; int err; sock_owned_by_me(sk); + err = check_sysctl_tcp_authopt(); + if (err) + return err; if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) return -EPERM; err = _copy_from_sockptr_tolerant((u8 *)&opt, sizeof(opt), optval, optlen); if (err)