Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755574AbaJWQEN (ORCPT ); Thu, 23 Oct 2014 12:04:13 -0400 Received: from cantor2.suse.de ([195.135.220.15]:35560 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752511AbaJWQEJ (ORCPT ); Thu, 23 Oct 2014 12:04:09 -0400 Date: Thu, 23 Oct 2014 18:04:05 +0200 From: Jan Kara To: Dmitry Kasatkin Cc: Jan Kara , Dmitry Kasatkin , Mimi Zohar , linux-security-module , linux-ima-devel , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 1/2] ima: check xattr value length in ima_inode_setxattr() Message-ID: <20141023160405.GC21034@quack.suse.cz> References: <5b1f234e8515c10c96a16868ff4341f29460f38f.1414071910.git.d.kasatkin@samsung.com> <20141023154007.GA21034@quack.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 23-10-14 18:59:07, Dmitry Kasatkin wrote: > 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. I see. Thanks for explanation. 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 -- Jan Kara SUSE Labs, CR -- 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/