From patchwork Wed May 12 14:50:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 436856 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 52D98C433ED for ; Wed, 12 May 2021 15:51:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 19EA261625 for ; Wed, 12 May 2021 15:51:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232467AbhELPwW (ORCPT ); Wed, 12 May 2021 11:52:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:50084 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236976AbhELPrl (ORCPT ); Wed, 12 May 2021 11:47:41 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 278A461CA8; Wed, 12 May 2021 15:24:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620833051; bh=KSK4APaPSeTB//NlRhdv8xPGF18qRoyCi8t649TVLRs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=08rUecc+AXvDv72h/awpXP+nF1h0bkut86S4Vwz120PsblCa/vsyjHlOa/XQJ7BEH 6iR5xkR5n54Ju28gC0x+nDWqr1wyyWje2amugpmcekSHCVNN0Lrq7sOvWvSA+G7/Ag xbuaCVi32Obgv0j8iW4f+k4kC9TPx9NggBcvw7s4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Or Cohen , Xin Long , "David S. Miller" Subject: [PATCH 5.10 530/530] sctp: delay auto_asconf init until binding the first addr Date: Wed, 12 May 2021 16:50:40 +0200 Message-Id: <20210512144837.158026354@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512144819.664462530@linuxfoundation.org> References: <20210512144819.664462530@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Xin Long commit 34e5b01186858b36c4d7c87e1a025071e8e2401f upstream. As Or Cohen described: If sctp_destroy_sock is called without sock_net(sk)->sctp.addr_wq_lock held and sp->do_auto_asconf is true, then an element is removed from the auto_asconf_splist without any proper locking. This can happen in the following functions: 1. In sctp_accept, if sctp_sock_migrate fails. 2. In inet_create or inet6_create, if there is a bpf program attached to BPF_CGROUP_INET_SOCK_CREATE which denies creation of the sctp socket. This patch is to fix it by moving the auto_asconf init out of sctp_init_sock(), by which inet_create()/inet6_create() won't need to operate it in sctp_destroy_sock() when calling sk_common_release(). It also makes more sense to do auto_asconf init while binding the first addr, as auto_asconf actually requires an ANY addr bind, see it in sctp_addr_wq_timeout_handler(). This addresses CVE-2021-23133. Fixes: 610236587600 ("bpf: Add new cgroup attach type to enable sock modifications") Reported-by: Or Cohen Signed-off-by: Xin Long Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sctp/socket.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -357,6 +357,18 @@ static struct sctp_af *sctp_sockaddr_af( return af; } +static void sctp_auto_asconf_init(struct sctp_sock *sp) +{ + struct net *net = sock_net(&sp->inet.sk); + + if (net->sctp.default_auto_asconf) { + spin_lock(&net->sctp.addr_wq_lock); + list_add_tail(&sp->auto_asconf_list, &net->sctp.auto_asconf_splist); + spin_unlock(&net->sctp.addr_wq_lock); + sp->do_auto_asconf = 1; + } +} + /* Bind a local address either to an endpoint or to an association. */ static int sctp_do_bind(struct sock *sk, union sctp_addr *addr, int len) { @@ -418,8 +430,10 @@ static int sctp_do_bind(struct sock *sk, return -EADDRINUSE; /* Refresh ephemeral port. */ - if (!bp->port) + if (!bp->port) { bp->port = inet_sk(sk)->inet_num; + sctp_auto_asconf_init(sp); + } /* Add the address to the bind address list. * Use GFP_ATOMIC since BHs will be disabled. @@ -4939,19 +4953,6 @@ static int sctp_init_sock(struct sock *s sk_sockets_allocated_inc(sk); sock_prot_inuse_add(net, sk->sk_prot, 1); - /* Nothing can fail after this block, otherwise - * sctp_destroy_sock() will be called without addr_wq_lock held - */ - if (net->sctp.default_auto_asconf) { - spin_lock(&sock_net(sk)->sctp.addr_wq_lock); - list_add_tail(&sp->auto_asconf_list, - &net->sctp.auto_asconf_splist); - sp->do_auto_asconf = 1; - spin_unlock(&sock_net(sk)->sctp.addr_wq_lock); - } else { - sp->do_auto_asconf = 0; - } - local_bh_enable(); return 0; @@ -9285,6 +9286,8 @@ static int sctp_sock_migrate(struct sock return err; } + sctp_auto_asconf_init(newsp); + /* Move any messages in the old socket's receive queue that are for the * peeled off association to the new socket's receive queue. */