From patchwork Wed Dec 14 22:01:57 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Abeni X-Patchwork-Id: 13073602 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 05ECFC4332F for ; Wed, 14 Dec 2022 22:03:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229704AbiLNWDT (ORCPT ); Wed, 14 Dec 2022 17:03:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45014 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229441AbiLNWDS (ORCPT ); Wed, 14 Dec 2022 17:03:18 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 625BE29CB4 for ; Wed, 14 Dec 2022 14:02:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1671055351; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1HyhyxRQPBcKRFEESR4J5ZAErFVsW4jq5nMw+0kspL4=; b=IDhO0z6Lqo3XC8b/01PHn/zwukjWQMNjaT21VRTEQLIoqUEdI9abb6VyYG9PU21AT6ss4y RsGaPnJyGphX32SjHUHMNxh/QUCH7sAKLJs2aeF5mwSXIrdEHYeRdqbEs5Kc4V1znyHG5o awcPcJH81xW3CZEJYqsL2upEWKWNtpQ= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-209-1vb05Q1vPMqPR1__6YnTwg-1; Wed, 14 Dec 2022 17:02:30 -0500 X-MC-Unique: 1vb05Q1vPMqPR1__6YnTwg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8CF0A101A521; Wed, 14 Dec 2022 22:02:29 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.39.195.136]) by smtp.corp.redhat.com (Postfix) with ESMTP id 878F740C2064; Wed, 14 Dec 2022 22:02:28 +0000 (UTC) From: Paolo Abeni To: linux-security-module@vger.kernel.org Cc: Paul Moore , selinux@vger.kernel.org, mptcp@lists.linux.dev Subject: [PATCH 1/2] security, lsm: Introduce security_mptcp_add_subflow() Date: Wed, 14 Dec 2022 23:01:57 +0100 Message-Id: <8a1157bafa09bbcfc42fb3617fb8512b364cd51c.1671054577.git.pabeni@redhat.com> In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: MPTCP can create subflows in kernel context, and later indirectly expose them to user-space, via the owning mptcp socket. As discussed in the reported link, the above causes unexpected failures for server, MPTCP-enabled applications. Let's introduce a new LSM hook to allow the security module to relabel the subflow according to the owing process. Link: https://lore.kernel.org/mptcp/CAHC9VhTNh-YwiyTds=P1e3rixEDqbRTFj22bpya=+qJqfcaMfg@mail.gmail.com/ Signed-off-by: Paolo Abeni --- include/linux/lsm_hook_defs.h | 1 + include/linux/lsm_hooks.h | 9 +++++++++ include/linux/security.h | 6 ++++++ net/mptcp/subflow.c | 6 ++++++ security/security.c | 5 +++++ 5 files changed, 27 insertions(+) diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index ed6cb2ac55fa..860e11e3a26b 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -343,6 +343,7 @@ LSM_HOOK(void, LSM_RET_VOID, sctp_sk_clone, struct sctp_association *asoc, struct sock *sk, struct sock *newsk) LSM_HOOK(int, 0, sctp_assoc_established, struct sctp_association *asoc, struct sk_buff *skb) +LSM_HOOK(int, 0, mptcp_add_subflow, struct sock *sk, struct sock *ssk) #endif /* CONFIG_SECURITY_NETWORK */ #ifdef CONFIG_SECURITY_INFINIBAND diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 0a5ba81f7367..84c9c4d4341e 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -1096,6 +1096,15 @@ * @skb pointer to skbuff of association packet. * Return 0 if permission is granted. * + * Security hooks for MPTCP + * + * @mptcp_add_subflow + * Update the labeling for the given MPTCP subflow, to match to + * owning MPTCP socket. + * @sk: the owning MPTCP socket + * @ssk: the new subflow + * Return 0 if successful, otherwise < 0 error code. + * * Security hooks for Infiniband * * @ib_pkey_access: diff --git a/include/linux/security.h b/include/linux/security.h index 5b67f208f7de..137a440e8e10 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -1479,6 +1479,7 @@ void security_sctp_sk_clone(struct sctp_association *asoc, struct sock *sk, struct sock *newsk); int security_sctp_assoc_established(struct sctp_association *asoc, struct sk_buff *skb); +int security_mptcp_add_subflow(struct sock *sk, struct sock *ssk); #else /* CONFIG_SECURITY_NETWORK */ static inline int security_unix_stream_connect(struct sock *sock, @@ -1706,6 +1707,11 @@ static inline int security_sctp_assoc_established(struct sctp_association *asoc, { return 0; } + +int security_mptcp_add_subflow(struct sock *sk, struct sock *ssk) +{ + return 0; +} #endif /* CONFIG_SECURITY_NETWORK */ #ifdef CONFIG_SECURITY_INFINIBAND diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index bd387d4b5a38..43b90784d914 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1680,6 +1680,10 @@ int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock) lock_sock(sf->sk); + err = security_mptcp_add_subflow(sk, sf->sk); + if (err) + goto release_ssk; + /* the newly created socket has to be in the same cgroup as its parent */ mptcp_attach_cgroup(sk, sf->sk); @@ -1692,6 +1696,8 @@ int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock) get_net_track(net, &sf->sk->ns_tracker, GFP_KERNEL); sock_inuse_add(net, 1); err = tcp_set_ulp(sf->sk, "mptcp"); + +release_ssk: release_sock(sf->sk); if (err) { diff --git a/security/security.c b/security/security.c index d1571900a8c7..3491a4fc2b1f 100644 --- a/security/security.c +++ b/security/security.c @@ -2493,6 +2493,11 @@ int security_sctp_assoc_established(struct sctp_association *asoc, } EXPORT_SYMBOL(security_sctp_assoc_established); +int security_mptcp_add_subflow(struct sock *sk, struct sock *ssk) +{ + return call_int_hook(mptcp_add_subflow, 0, sk, ssk); +} + #endif /* CONFIG_SECURITY_NETWORK */ #ifdef CONFIG_SECURITY_INFINIBAND