From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=unavailable 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 5BE7DC2BBE2 for ; Sat, 7 Dec 2019 16:16:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 28B0A2176D for ; Sat, 7 Dec 2019 16:16:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="cmCB3BJq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726442AbfLGQQm (ORCPT ); Sat, 7 Dec 2019 11:16:42 -0500 Received: from aserp2120.oracle.com ([141.146.126.78]:58984 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726409AbfLGQQm (ORCPT ); Sat, 7 Dec 2019 11:16:42 -0500 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xB7G5Uwd104906; Sat, 7 Dec 2019 16:16:20 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id; s=corp-2019-08-05; bh=Z1g6ETTgditdnaxVzYZyvy9YazZMEqW70B3znyg7hMM=; b=cmCB3BJqMlZVXlsjfjysBdPSgu+zWNVQZXzaaVmS8LO6pLh8XOjcK06pIM0EPZ8/GFpi F38V+aA55LkZMtZ18OdrUEEguHfz+y3CWU+opDksttJvVEgfu6frJVw/LKcML8LpzZcs UMeTZXLMngynXMRQYUcF1tyGeZ4P9+AqtNW7imuKXz1U+vsWBNhupTmd7u12OPkpfgA2 a0ENKDFDBRwge52xh1qxlA0Nejo57aq0PKLR3PAcZDNVXKdyfSu2Kydyw5MZA4cUkmc/ kD2/39CAoBCSYIYyqjuWtNKtfR/kqgXCS5/f8El2q1WSTsQNtinlbGPXKjaZ4WhsjYva AQ== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by aserp2120.oracle.com with ESMTP id 2wr41psk04-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 07 Dec 2019 16:16:20 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xB7GAatn058986; Sat, 7 Dec 2019 16:16:19 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3030.oracle.com with ESMTP id 2wr17cv8t6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 07 Dec 2019 16:16:19 +0000 Received: from abhmp0014.oracle.com (abhmp0014.oracle.com [141.146.116.20]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id xB7GGGHZ001543; Sat, 7 Dec 2019 16:16:16 GMT Received: from localhost.us.oracle.com (/10.147.27.2) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sat, 07 Dec 2019 08:16:16 -0800 From: Eric Snowberg To: gregkh@linuxfoundation.org Cc: rafael@kernel.org, dhowells@redhat.com, matthewgarrett@google.com, jmorris@namei.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, willy@infradead.org, eric.snowberg@oracle.com Subject: [PATCH v2] debugfs: Return -EPERM when locked down Date: Sat, 7 Dec 2019 11:16:03 -0500 Message-Id: <20191207161603.35907-1-eric.snowberg@oracle.com> X-Mailer: git-send-email 2.18.1 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9463 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=1 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1912070139 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9463 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1912070139 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org When lockdown is enabled, debugfs_is_locked_down returns 1. It will then trigger the following: WARNING: CPU: 48 PID: 3747 CPU: 48 PID: 3743 Comm: bash Not tainted 5.4.0-1946.x86_64 #1 Hardware name: Oracle Corporation ORACLE SERVER X7-2/ASM, MB, X7-2, BIOS 41060400 05/20/2019 RIP: 0010:do_dentry_open+0x343/0x3a0 Code: 00 40 08 00 45 31 ff 48 c7 43 28 40 5b e7 89 e9 02 ff ff ff 48 8b 53 28 4c 8b 72 70 4d 85 f6 0f 84 10 fe ff ff e9 f5 fd ff ff <0f> 0b 41 bf ea ff ff ff e9 3b ff ff ff 41 bf e6 ff ff ff e9 b4 fe RSP: 0018:ffffb8740dde7ca0 EFLAGS: 00010202 RAX: ffffffff89e88a40 RBX: ffff928c8e6b6f00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff928dbfd97778 RDI: ffff9285cff685c0 RBP: ffffb8740dde7cc8 R08: 0000000000000821 R09: 0000000000000030 R10: 0000000000000057 R11: ffffb8740dde7a98 R12: ffff926ec781c900 R13: ffff928c8e6b6f10 R14: ffffffff8936e190 R15: 0000000000000001 FS: 00007f45f6777740(0000) GS:ffff928dbfd80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fff95e0d5d8 CR3: 0000001ece562006 CR4: 00000000007606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: vfs_open+0x2d/0x30 path_openat+0x2d4/0x1680 ? tty_mode_ioctl+0x298/0x4c0 do_filp_open+0x93/0x100 ? strncpy_from_user+0x57/0x1b0 ? __alloc_fd+0x46/0x150 do_sys_open+0x182/0x230 __x64_sys_openat+0x20/0x30 do_syscall_64+0x60/0x1b0 entry_SYSCALL_64_after_hwframe+0x170/0x1d5 RIP: 0033:0x7f45f5e5ce02 Code: 25 00 00 41 00 3d 00 00 41 00 74 4c 48 8d 05 25 59 2d 00 8b 00 85 c0 75 6d 89 f2 b8 01 01 00 00 48 89 fe bf 9c ff ff ff 0f 05 <48> 3d 00 f0 ff ff 0f 87 a2 00 00 00 48 8b 4c 24 28 64 48 33 0c 25 RSP: 002b:00007fff95e0d2e0 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000561178c069b0 RCX: 00007f45f5e5ce02 RDX: 0000000000000241 RSI: 0000561178c08800 RDI: 00000000ffffff9c RBP: 00007fff95e0d3e0 R08: 0000000000000020 R09: 0000000000000005 R10: 00000000000001b6 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000003 R14: 0000000000000001 R15: 0000561178c08800 Change the return type to int and return -EPERM when lockdown is enabled to remove the warning above. Also rename debugfs_is_locked_down to debugfs_locked_down to make it sound less like it returns a boolean. Fixes: 5496197f9b08 ("debugfs: Restrict debugfs when the kernel is locked down") Signed-off-by: Eric Snowberg Reviewed-by: Matthew Wilcox (Oracle) --- v2 changes: - debugfs_locked_down rename - recommended by Matthew Wilcox fs/debugfs/file.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index dede25247b81..18eeeb093a68 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -142,18 +142,21 @@ EXPORT_SYMBOL_GPL(debugfs_file_put); * We also need to exclude any file that has ways to write or alter it as root * can bypass the permissions check. */ -static bool debugfs_is_locked_down(struct inode *inode, - struct file *filp, - const struct file_operations *real_fops) +static int debugfs_locked_down(struct inode *inode, + struct file *filp, + const struct file_operations *real_fops) { if ((inode->i_mode & 07777) == 0444 && !(filp->f_mode & FMODE_WRITE) && !real_fops->unlocked_ioctl && !real_fops->compat_ioctl && !real_fops->mmap) - return false; + return 0; - return security_locked_down(LOCKDOWN_DEBUGFS); + if (security_locked_down(LOCKDOWN_DEBUGFS)) + return -EPERM; + + return 0; } static int open_proxy_open(struct inode *inode, struct file *filp) @@ -168,7 +171,7 @@ static int open_proxy_open(struct inode *inode, struct file *filp) real_fops = debugfs_real_fops(filp); - r = debugfs_is_locked_down(inode, filp, real_fops); + r = debugfs_locked_down(inode, filp, real_fops); if (r) goto out; @@ -298,7 +301,7 @@ static int full_proxy_open(struct inode *inode, struct file *filp) real_fops = debugfs_real_fops(filp); - r = debugfs_is_locked_down(inode, filp, real_fops); + r = debugfs_locked_down(inode, filp, real_fops); if (r) goto out; -- 2.18.1