From patchwork Sat Dec 12 08:57:37 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steffen Klassert X-Patchwork-Id: 343203 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 01CCEC4361B for ; Sat, 12 Dec 2020 10:14:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9179122D50 for ; Sat, 12 Dec 2020 10:14:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2438597AbgLLKN7 (ORCPT ); Sat, 12 Dec 2020 05:13:59 -0500 Received: from a.mx.secunet.com ([62.96.220.36]:48606 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405606AbgLLKNq (ORCPT ); Sat, 12 Dec 2020 05:13:46 -0500 Received: from localhost (localhost [127.0.0.1]) by a.mx.secunet.com (Postfix) with ESMTP id 2263620491; Sat, 12 Dec 2020 09:57:41 +0100 (CET) X-Virus-Scanned: by secunet Received: from a.mx.secunet.com ([127.0.0.1]) by localhost (a.mx.secunet.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id GklH7vDJsZat; Sat, 12 Dec 2020 09:57:40 +0100 (CET) Received: from mail-essen-02.secunet.de (unknown [10.53.40.205]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by a.mx.secunet.com (Postfix) with ESMTPS id 78953201D3; Sat, 12 Dec 2020 09:57:40 +0100 (CET) Received: from mbx-essen-01.secunet.de (10.53.40.197) by mail-essen-02.secunet.de (10.53.40.205) with Microsoft SMTP Server (TLS) id 14.3.487.0; Sat, 12 Dec 2020 09:57:40 +0100 Received: from gauss2.secunet.de (10.182.7.193) by mbx-essen-01.secunet.de (10.53.40.197) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2044.4; Sat, 12 Dec 2020 09:57:40 +0100 Received: by gauss2.secunet.de (Postfix, from userid 1000) id B69B93182CE6; Sat, 12 Dec 2020 09:57:39 +0100 (CET) From: Steffen Klassert To: David Miller , Jakub Kicinski CC: Herbert Xu , Steffen Klassert , Subject: [PATCH] xfrm: redact SA secret with lockdown confidentiality Date: Sat, 12 Dec 2020 09:57:37 +0100 Message-ID: <20201212085737.2101294-2-steffen.klassert@secunet.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201212085737.2101294-1-steffen.klassert@secunet.com> References: <20201212085737.2101294-1-steffen.klassert@secunet.com> MIME-Version: 1.0 X-ClientProxiedBy: cas-essen-01.secunet.de (10.53.40.201) To mbx-essen-01.secunet.de (10.53.40.197) X-EXCLAIMER-MD-CONFIG: 2c86f778-e09b-4440-8b15-867914633a10 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Antony Antony redact XFRM SA secret in the netlink response to xfrm_get_sa() or dumpall sa. Enable lockdown, confidentiality mode, at boot or at run time. e.g. when enabled: cat /sys/kernel/security/lockdown none integrity [confidentiality] ip xfrm state src 172.16.1.200 dst 172.16.1.100 proto esp spi 0x00000002 reqid 2 mode tunnel replay-window 0 aead rfc4106(gcm(aes)) 0x0000000000000000000000000000000000000000 96 note: the aead secret is redacted. Redacting secret is also a FIPS 140-2 requirement. v1->v2 - add size checks before memset calls v2->v3 - replace spaces with tabs for consistency v3->v4 - use kernel lockdown instead of a /proc setting v4->v5 - remove kconfig option Reviewed-by: Stephan Mueller Signed-off-by: Antony Antony Signed-off-by: Steffen Klassert --- include/linux/security.h | 1 + net/xfrm/xfrm_user.c | 74 ++++++++++++++++++++++++++++++++++++---- security/security.c | 1 + 3 files changed, 69 insertions(+), 7 deletions(-) diff --git a/include/linux/security.h b/include/linux/security.h index bc2725491560..1112a79a7dba 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -127,6 +127,7 @@ enum lockdown_reason { LOCKDOWN_PERF, LOCKDOWN_TRACEFS, LOCKDOWN_XMON_RW, + LOCKDOWN_XFRM_SECRET, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index d0c32a8fcc4a..0727ac853b55 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -848,21 +848,84 @@ static int copy_user_offload(struct xfrm_state_offload *xso, struct sk_buff *skb return 0; } +static bool xfrm_redact(void) +{ + return IS_ENABLED(CONFIG_SECURITY) && + security_locked_down(LOCKDOWN_XFRM_SECRET); +} + static int copy_to_user_auth(struct xfrm_algo_auth *auth, struct sk_buff *skb) { struct xfrm_algo *algo; + struct xfrm_algo_auth *ap; struct nlattr *nla; + bool redact_secret = xfrm_redact(); nla = nla_reserve(skb, XFRMA_ALG_AUTH, sizeof(*algo) + (auth->alg_key_len + 7) / 8); if (!nla) return -EMSGSIZE; - algo = nla_data(nla); strncpy(algo->alg_name, auth->alg_name, sizeof(algo->alg_name)); - memcpy(algo->alg_key, auth->alg_key, (auth->alg_key_len + 7) / 8); + + if (redact_secret && auth->alg_key_len) + memset(algo->alg_key, 0, (auth->alg_key_len + 7) / 8); + else + memcpy(algo->alg_key, auth->alg_key, + (auth->alg_key_len + 7) / 8); algo->alg_key_len = auth->alg_key_len; + nla = nla_reserve(skb, XFRMA_ALG_AUTH_TRUNC, xfrm_alg_auth_len(auth)); + if (!nla) + return -EMSGSIZE; + ap = nla_data(nla); + memcpy(ap, auth, sizeof(struct xfrm_algo_auth)); + if (redact_secret && auth->alg_key_len) + memset(ap->alg_key, 0, (auth->alg_key_len + 7) / 8); + else + memcpy(ap->alg_key, auth->alg_key, + (auth->alg_key_len + 7) / 8); + return 0; +} + +static int copy_to_user_aead(struct xfrm_algo_aead *aead, struct sk_buff *skb) +{ + struct nlattr *nla = nla_reserve(skb, XFRMA_ALG_AEAD, aead_len(aead)); + struct xfrm_algo_aead *ap; + bool redact_secret = xfrm_redact(); + + if (!nla) + return -EMSGSIZE; + + ap = nla_data(nla); + memcpy(ap, aead, sizeof(*aead)); + + if (redact_secret && aead->alg_key_len) + memset(ap->alg_key, 0, (aead->alg_key_len + 7) / 8); + else + memcpy(ap->alg_key, aead->alg_key, + (aead->alg_key_len + 7) / 8); + return 0; +} + +static int copy_to_user_ealg(struct xfrm_algo *ealg, struct sk_buff *skb) +{ + struct xfrm_algo *ap; + bool redact_secret = xfrm_redact(); + struct nlattr *nla = nla_reserve(skb, XFRMA_ALG_CRYPT, + xfrm_alg_len(ealg)); + if (!nla) + return -EMSGSIZE; + + ap = nla_data(nla); + memcpy(ap, ealg, sizeof(*ealg)); + + if (redact_secret && ealg->alg_key_len) + memset(ap->alg_key, 0, (ealg->alg_key_len + 7) / 8); + else + memcpy(ap->alg_key, ealg->alg_key, + (ealg->alg_key_len + 7) / 8); + return 0; } @@ -906,20 +969,17 @@ static int copy_to_user_state_extra(struct xfrm_state *x, goto out; } if (x->aead) { - ret = nla_put(skb, XFRMA_ALG_AEAD, aead_len(x->aead), x->aead); + ret = copy_to_user_aead(x->aead, skb); if (ret) goto out; } if (x->aalg) { ret = copy_to_user_auth(x->aalg, skb); - if (!ret) - ret = nla_put(skb, XFRMA_ALG_AUTH_TRUNC, - xfrm_alg_auth_len(x->aalg), x->aalg); if (ret) goto out; } if (x->ealg) { - ret = nla_put(skb, XFRMA_ALG_CRYPT, xfrm_alg_len(x->ealg), x->ealg); + ret = copy_to_user_ealg(x->ealg, skb); if (ret) goto out; } diff --git a/security/security.c b/security/security.c index a28045dc9e7f..abff77c1c8a7 100644 --- a/security/security.c +++ b/security/security.c @@ -65,6 +65,7 @@ const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_PERF] = "unsafe use of perf", [LOCKDOWN_TRACEFS] = "use of tracefs", [LOCKDOWN_XMON_RW] = "xmon read and write access", + [LOCKDOWN_XFRM_SECRET] = "xfrm SA secret", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", };