From patchwork Tue Apr 5 07:27:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 557373 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 A7EB7C352A7 for ; Tue, 5 Apr 2022 10:08:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353497AbiDEKH7 (ORCPT ); Tue, 5 Apr 2022 06:07:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44262 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344361AbiDEJTe (ORCPT ); Tue, 5 Apr 2022 05:19:34 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E3C8011F; Tue, 5 Apr 2022 02:07:56 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 9EE72B81A12; Tue, 5 Apr 2022 09:07:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E940DC385A1; Tue, 5 Apr 2022 09:07:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649149674; bh=qBElXJ90QRgQ8W5VnsNr6T5Wz+r+3jv9YBNbGL+C/PI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=adNZPA11YHOGWheHySjb7gIBxAO6jT+V8e0kM+DE/1sglWxZTV+bK/udLK4zsLEov U/8EZhtG2D/sDILHttpMvWYxFOzsQDwn/lI9mCYSlR4nn+09tHTCO3RkrKFSRcKC35 5XN//MB8YDq9seyGXBeymjUke55v1bN9za1uMzeg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+d1e3b1d92d25abf97943@syzkaller.appspotmail.com, Casey Schaufler , James Morris , Paul Moore , Sasha Levin Subject: [PATCH 5.16 0751/1017] LSM: general protection fault in legacy_parse_param Date: Tue, 5 Apr 2022 09:27:44 +0200 Message-Id: <20220405070416.552864745@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070354.155796697@linuxfoundation.org> References: <20220405070354.155796697@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Casey Schaufler [ Upstream commit ecff30575b5ad0eda149aadad247b7f75411fd47 ] The usual LSM hook "bail on fail" scheme doesn't work for cases where a security module may return an error code indicating that it does not recognize an input. In this particular case Smack sees a mount option that it recognizes, and returns 0. A call to a BPF hook follows, which returns -ENOPARAM, which confuses the caller because Smack has processed its data. The SELinux hook incorrectly returns 1 on success. There was a time when this was correct, however the current expectation is that it return 0 on success. This is repaired. Reported-by: syzbot+d1e3b1d92d25abf97943@syzkaller.appspotmail.com Signed-off-by: Casey Schaufler Acked-by: James Morris Signed-off-by: Paul Moore Signed-off-by: Sasha Levin --- security/security.c | 17 +++++++++++++++-- security/selinux/hooks.c | 5 ++--- 2 files changed, 17 insertions(+), 5 deletions(-) diff --git a/security/security.c b/security/security.c index cf6615b5e820..745a8bf66d91 100644 --- a/security/security.c +++ b/security/security.c @@ -884,9 +884,22 @@ int security_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc) return call_int_hook(fs_context_dup, 0, fc, src_fc); } -int security_fs_context_parse_param(struct fs_context *fc, struct fs_parameter *param) +int security_fs_context_parse_param(struct fs_context *fc, + struct fs_parameter *param) { - return call_int_hook(fs_context_parse_param, -ENOPARAM, fc, param); + struct security_hook_list *hp; + int trc; + int rc = -ENOPARAM; + + hlist_for_each_entry(hp, &security_hook_heads.fs_context_parse_param, + list) { + trc = hp->hook.fs_context_parse_param(fc, param); + if (trc == 0) + rc = 0; + else if (trc != -ENOPARAM) + return trc; + } + return rc; } int security_sb_alloc(struct super_block *sb) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 93eac9464c5f..69b0709bd156 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2916,10 +2916,9 @@ static int selinux_fs_context_parse_param(struct fs_context *fc, return opt; rc = selinux_add_opt(opt, param->string, &fc->security); - if (!rc) { + if (!rc) param->string = NULL; - rc = 1; - } + return rc; }