Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755780AbaJWP7L (ORCPT ); Thu, 23 Oct 2014 11:59:11 -0400 Received: from mail-wi0-f169.google.com ([209.85.212.169]:33486 "EHLO mail-wi0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754349AbaJWP7I (ORCPT ); Thu, 23 Oct 2014 11:59:08 -0400 MIME-Version: 1.0 In-Reply-To: <20141023154007.GA21034@quack.suse.cz> References: <5b1f234e8515c10c96a16868ff4341f29460f38f.1414071910.git.d.kasatkin@samsung.com> <20141023154007.GA21034@quack.suse.cz> Date: Thu, 23 Oct 2014 18:59:07 +0300 Message-ID: Subject: Re: [PATCH 1/2] ima: check xattr value length in ima_inode_setxattr() From: Dmitry Kasatkin To: Jan Kara Cc: Dmitry Kasatkin , Mimi Zohar , linux-security-module , linux-ima-devel , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23 October 2014 18:40, Jan Kara wrote: > On Thu 23-10-14 16:47:17, Dmitry Kasatkin wrote: >> 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. >> > .. >> >> Reported-by: Jan Kara >> Signed-off-by: Dmitry Kasatkin >> --- >> security/integrity/ima/ima_appraise.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c >> index 5b845af..f07aacd 100644 >> --- a/security/integrity/ima/ima_appraise.c >> +++ b/security/integrity/ima/ima_appraise.c >> @@ -378,6 +378,8 @@ 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) { >> + if (!xattr_value_len) >> + return -EINVAL; > Wouldn't it be safer to return EINVAL whenever xattr_value_len != > sizeof(evm_ima_xattr_data)? In this function we only use first byte to identify attribute type. sizeof(evm_ima_xattr_data) is SHA1_DIGEST_SIZE + 1. But IMA may use any other algorithm where digest size is different. - Dmitry > > Honza >> ima_reset_appraise_flags(dentry->d_inode, >> (xvalue->type == EVM_IMA_XATTR_DIGSIG) ? 1 : 0); >> result = 0; >> -- >> 1.9.1 >> > -- > Jan Kara > SUSE Labs, CR -- Thanks, Dmitry -- 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/