From patchwork Mon Nov 1 16:34:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leonard Crestez X-Patchwork-Id: 12596625 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E936FC4167B for ; Mon, 1 Nov 2021 16:35:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CDFB2610FD for ; Mon, 1 Nov 2021 16:35:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232898AbhKAQiX (ORCPT ); Mon, 1 Nov 2021 12:38:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57082 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232839AbhKAQiS (ORCPT ); Mon, 1 Nov 2021 12:38:18 -0400 Received: from mail-ed1-x530.google.com (mail-ed1-x530.google.com [IPv6:2a00:1450:4864:20::530]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE2E3C061764; Mon, 1 Nov 2021 09:35:44 -0700 (PDT) Received: by mail-ed1-x530.google.com with SMTP id z20so66625584edc.13; Mon, 01 Nov 2021 09:35:44 -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=RmHVS7Eq+vaOp7+GRIKxaKy7LMv75f9ozhcptpjvtP4=; b=dKioVMCXODRAcb+mi+Bd17gh15NZDEDUki8dML12N/971Z3kAYG+jzqSfzYPeVQUYW h7tUXtW7A5f9cGm6ULZdgEE8WmdJhCi1+QX8ZzMwfYCGn80OC4SNEcU45aYonS1xB8b9 sa9d6vhKYL3rWXWh7HYTH0YOSSWUchDEWsMXPEjY/vMLer4CqQXwuFBJdH9mtdj9HANl HfyZyo1472EqrJ9Qw+1vb5Qp9Lc2UAlkyeHLDcCAq57uOqHaKiJoWDlzIsXNIDUQH2vU /zv98UfloGVRzJV70e7KYJu6C4Ex/CcpoTeX5os1V8mIzolY96fSF3GkbV/TIQtOMvnU wEFw== 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=RmHVS7Eq+vaOp7+GRIKxaKy7LMv75f9ozhcptpjvtP4=; b=Phw/UWPlv/mMtoQOzA5BOdlFkWylc/JsHfRIuyBu4+q7HWGTJAq4FwPcIPHNoGLqDX Httdq6Z0EN9gyX0YWA+ypYQwLrePZ2BMNLHhX9UwJJLOtDJHVEkiREGj8ayWuNoC6Svj ZkORbm2OveGXZxaxkPEI9bL1iVeJN56UEUoAnuUpVfUGFIRexf8VBQmC4BCuuNd/4Spo 8wP0LI7sqjo6wkvDU2FFvpFmjvMxuBo5q+qD5zw5t8JZCOemMDifEcJgDrE/tjDoU5jg PqBlMg+sph+Dyxv2jcp4YaGYgfzZrGAbWchtFvGcVRIm841LU2ZUeK1SH7uMmYJd98wx MKZw== X-Gm-Message-State: AOAM532OT0lvsfXk37L2X7zT4mgpgr7ToVGyvrnWKAYvtWduZRGkMQ1f 90jzUXwWTNbIh22hPu5nNSs= X-Google-Smtp-Source: ABdhPJydlcqjMqxzyKzb+8AGYTQcGqBapguFfb1WTzt4tv1N+I0c7RtJi6ffd80fGNHwv9fZc4alyw== X-Received: by 2002:a17:906:660b:: with SMTP id b11mr37836198ejp.427.1635784543415; Mon, 01 Nov 2021 09:35:43 -0700 (PDT) Received: from ponky.lan ([2a04:241e:501:3870:f5f:2085:7f25:17c]) by smtp.gmail.com with ESMTPSA id f25sm4124583edv.90.2021.11.01.09.35.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Nov 2021 09:35:42 -0700 (PDT) From: Leonard Crestez To: David Ahern , Shuah Khan , Dmitry Safonov <0x7f454c46@gmail.com>, Eric Dumazet Cc: "David S. Miller" , Herbert Xu , Kuniyuki Iwashima , Hideaki YOSHIFUJI , Jakub Kicinski , Yuchung Cheng , Francesco Ruggeri , Mat Martineau , Christoph Paasch , Ivan Delalande , Priyaranjan Jha , netdev@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 09/25] tcp: authopt: Disable via sysctl by default Date: Mon, 1 Nov 2021 18:34:44 +0200 Message-Id: <137399b962131c278acbfa5446a3b6d59aa0547b.1635784253.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 | 10 ++++++++++ net/ipv4/tcp_authopt.c | 13 ++++++++++++- 4 files changed, 29 insertions(+), 1 deletion(-) diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index 16b8bf72feaf..3f00681f73d7 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -987,10 +987,16 @@ tcp_limit_output_bytes - INTEGER tcp_challenge_ack_limit - INTEGER Limits number of Challenge ACK sent per second, as recommended in RFC 5961 (Improving TCP's Robustness to Blind In-Window Attacks) Default: 1000 +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 8bb76128ed11..a505db1dd67b 100644 --- a/include/net/tcp_authopt.h +++ b/include/net/tcp_authopt.h @@ -65,10 +65,11 @@ struct tcp_authopt_info { /** @dst_isn: Remote Initial Sequence Number */ u32 dst_isn; }; #ifdef CONFIG_TCP_AUTHOPT +extern int sysctl_tcp_authopt; DECLARE_STATIC_KEY_FALSE(tcp_authopt_needed); 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); diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 97eb54774924..cc34de6e4817 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 two = 2; static int three __maybe_unused = 3; static int four = 4; static int thousand = 1000; @@ -583,10 +584,19 @@ 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_dointvec, + }, +#endif { } }; static struct ctl_table ipv4_net_table[] = { { diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c index 5e80e5e5e36e..7c49dcce7d24 100644 --- a/net/ipv4/tcp_authopt.c +++ b/net/ipv4/tcp_authopt.c @@ -3,10 +3,15 @@ #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); EXPORT_SYMBOL(tcp_authopt_needed); /* All current algorithms have a mac length of 12 but crypto API digestsize can be larger */ @@ -360,10 +365,12 @@ 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); + if (!sysctl_tcp_authopt) + return -EPERM; err = _copy_from_sockptr_tolerant((u8 *)&opt, sizeof(opt), optval, optlen); if (err) return err; @@ -382,13 +389,15 @@ 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; + memset(opt, 0, sizeof(*opt)); sock_owned_by_me(sk); + if (!sysctl_tcp_authopt) + return -EPERM; - memset(opt, 0, sizeof(*opt)); info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk)); if (!info) return -ENOENT; opt->flags = info->flags & TCP_AUTHOPT_KNOWN_FLAGS; @@ -451,10 +460,12 @@ int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen) struct tcp_authopt_key_info *key_info, *old_key_info; struct tcp_authopt_alg_imp *alg; int err; sock_owned_by_me(sk); + if (!sysctl_tcp_authopt) + return -EPERM; err = _copy_from_sockptr_tolerant((u8 *)&opt, sizeof(opt), optval, optlen); if (err) return err;