Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753191AbaJXHHu (ORCPT ); Fri, 24 Oct 2014 03:07:50 -0400 Received: from mailout2.w1.samsung.com ([210.118.77.12]:21235 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750888AbaJXHHp (ORCPT ); Fri, 24 Oct 2014 03:07:45 -0400 X-AuditID: cbfec7f4-b7f6c6d00000120b-7d-5449fabec6ba From: Dmitry Kasatkin To: zohar@linux.vnet.ibm.com, linux-security-module@vger.kernel.org, linux-ima-devel@lists.sourceforge.net Cc: linux-kernel@vger.kernel.org, jack@suse.cz, jmorris@namei.org, dmitry.kasatkin@gmail.com, Dmitry Kasatkin Subject: [PATCH v2 1/2] ima: check xattr value length in ima_inode_setxattr() Date: Fri, 24 Oct 2014 10:07:05 +0300 Message-id: <53afed717c1dc6b3588cca7c0a6b69650edc2ad2.1414134113.git.d.kasatkin@samsung.com> X-Mailer: git-send-email 1.9.1 In-reply-to: References: In-reply-to: References: X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprFLMWRmVeSWpSXmKPExsVy+t/xa7r7fnmGGNyaJGRx6+9eZosvS+ss Zk9vZrJYt34xk8XLGfPYLS7vmsNm8aHnEZvFpxWTmB04PHbOusvu8eDQZhaP3Qs+M3n0fE/2 6NuyitHjzIIj7B6fN8kFsEdx2aSk5mSWpRbp2yVwZUxcvZy54KxCxeauTrYGxg3SXYwcHBIC JhKzDxd2MXICmWISF+6tZ+ti5OIQEljKKDFp5QNmkISQQCeTxMPPTCA2m4CexIbmH+wgtohA jsSjP6/ZQRqYBToYJTb+uA5WJCzgK3Hsyh4wm0VAVeL17/lgNq9AnMS5vqnMENvkJE4em8wK YnMKWEk8+3KMFWKZpcT8vk/suMQnMPIvYGRYxSiaWppcUJyUnmuoV5yYW1yal66XnJ+7iRES nl92MC4+ZnWIUYCDUYmHtyLZI0SINbGsuDL3EKMEB7OSCG/iR88QId6UxMqq1KL8+KLSnNTi Q4xMHJxSDYwem7h6/aoepl6ZEyO++7bKnQ9Lt+bHat7lanxc4JJn7vdxj/wXLne9rlZLtZ1u /1N+NX/bf/ljf67J5oLTeYc/Kmr91L/s7DVlzf16K2uex6qd+7bcblLxvL2bP2QzX0HSiiWn 9s2QSth39cm273nV8bwxL5TKxWuen96soWKoWfpiLgvPC2ElluKMREMt5qLiRADZRA1rLQIA AA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ima_inode_setxattr() can be called with no value. Function does not check the length so that following command can be used to produce kernel oops: setfattr -n security.ima FOO. This patch fixes it. Changes in v2: * testing validity of xattr type * allow setting hash only in fix or log mode (Mimi) [ 261.562522] BUG: unable to handle kernel NULL pointer dereference at (null) [ 261.564109] IP: [] ima_inode_setxattr+0x3e/0x5a [ 261.564109] PGD 3112f067 PUD 42965067 PMD 0 [ 261.564109] Oops: 0000 [#1] SMP [ 261.564109] Modules linked in: bridge stp llc evdev serio_raw i2c_piix4 button fuse [ 261.564109] CPU: 0 PID: 3299 Comm: setxattr Not tainted 3.16.0-kds+ #2924 [ 261.564109] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 261.564109] task: ffff8800428c2430 ti: ffff880042be0000 task.ti: ffff880042be0000 [ 261.564109] RIP: 0010:[] [] ima_inode_setxattr+0x3e/0x5a [ 261.564109] RSP: 0018:ffff880042be3d50 EFLAGS: 00010246 [ 261.564109] RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000015 [ 261.564109] RDX: 0000001500000000 RSI: 0000000000000000 RDI: ffff8800375cc600 [ 261.564109] RBP: ffff880042be3d68 R08: 0000000000000000 R09: 00000000004d6256 [ 261.564109] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88002149ba00 [ 261.564109] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 261.564109] FS: 00007f6c1e219740(0000) GS:ffff88005da00000(0000) knlGS:0000000000000000 [ 261.564109] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 261.564109] CR2: 0000000000000000 CR3: 000000003b35a000 CR4: 00000000000006f0 [ 261.564109] Stack: [ 261.564109] ffff88002149ba00 ffff880042be3df8 0000000000000000 ffff880042be3d98 [ 261.564109] ffffffff812a101b ffff88002149ba00 ffff880042be3df8 0000000000000000 [ 261.564109] 0000000000000000 ffff880042be3de0 ffffffff8116d08a ffff880042be3dc8 [ 261.564109] Call Trace: [ 261.564109] [] security_inode_setxattr+0x48/0x6a [ 261.564109] [] vfs_setxattr+0x6b/0x9f [ 261.564109] [] setxattr+0x122/0x16c [ 261.564109] [] ? mnt_want_write+0x21/0x45 [ 261.564109] [] ? __sb_start_write+0x10f/0x143 [ 261.564109] [] ? mnt_want_write+0x21/0x45 [ 261.564109] [] ? __mnt_want_write+0x48/0x4f [ 261.564109] [] SyS_setxattr+0x6e/0xb0 [ 261.564109] [] system_call_fastpath+0x16/0x1b [ 261.564109] Code: 48 89 f7 48 c7 c6 58 36 81 81 53 31 db e8 73 27 04 00 85 c0 75 28 bf 15 00 00 00 e8 8a a5 d9 ff 84 c0 75 05 83 cb ff eb 15 31 f6 <41> 80 7d 00 03 49 8b 7c 24 68 40 0f 94 c6 e8 e1 f9 ff ff 89 d8 [ 261.564109] RIP [] ima_inode_setxattr+0x3e/0x5a [ 261.564109] RSP [ 261.564109] CR2: 0000000000000000 [ 261.599998] ---[ end trace 39a89a3fc267e652 ]--- Reported-by: Jan Kara Signed-off-by: Dmitry Kasatkin --- security/integrity/ima/ima_appraise.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 9226854..e302cbf 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -378,8 +378,17 @@ int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name, result = ima_protect_xattr(dentry, xattr_name, xattr_value, xattr_value_len); if (result == 1) { - ima_reset_appraise_flags(dentry->d_inode, - (xvalue->type == EVM_IMA_XATTR_DIGSIG) ? 1 : 0); + bool digsig; + + if (!xattr_value_len || + (xvalue->type != IMA_XATTR_DIGEST && + xvalue->type != IMA_XATTR_DIGEST_NG && + xvalue->type != EVM_IMA_XATTR_DIGSIG)) + return -EINVAL; + digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG); + if (!digsig && (ima_appraise & IMA_APPRAISE_ENFORCE)) + return -EPERM; + ima_reset_appraise_flags(dentry->d_inode, digsig); result = 0; } return result; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/