From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757074AbaHHVQo (ORCPT ); Fri, 8 Aug 2014 17:16:44 -0400 Received: from static.92.5.9.176.clients.your-server.de ([176.9.5.92]:33147 "EHLO mail.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932544AbaHHUvl (ORCPT ); Fri, 8 Aug 2014 16:51:41 -0400 Date: Fri, 8 Aug 2014 22:51:37 +0200 From: "Serge E. Hallyn" To: Konstantin Khlebnikov Cc: Casey Schaufler , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, James Morris , "Serge E. Hallyn" Subject: Re: [PATCH 3/3] Smack: remove unneeded NULL-termination from securtity label Message-ID: <20140808205137.GD25352@mail.hallyn.com> References: <20140807165233.13463.55258.stgit@buzz> <20140807165249.13463.60191.stgit@buzz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140807165249.13463.60191.stgit@buzz> 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 Quoting Konstantin Khlebnikov (k.khlebnikov@samsung.com): > Values of extended attributes are stored as binary blobs. NULL-termination > of them isn't required. It just wastes disk space and confuses command-line > tools like getfattr because they have to print that zero byte at the end. > > This patch removes terminating zero byte from initial security label in > smack_inode_init_security and cuts it out in function smack_inode_getsecurity > which is used by syscall getxattr. This change seems completely safe, because > function smk_parse_smack ignores everything after first zero byte. > > Signed-off-by: Konstantin Khlebnikov selinux doesn't seem to do it this way, and apparmor doesn't use these at all, but your reasoning does seem correct. Acked-by: Serge Hallyn > --- > security/smack/smack_lsm.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c > index afa5ad0..16ae853 100644 > --- a/security/smack/smack_lsm.c > +++ b/security/smack/smack_lsm.c > @@ -672,7 +672,7 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir, > } > > if (len) > - *len = strlen(isp) + 1; > + *len = strlen(isp); > > return 0; > } > @@ -1076,7 +1076,7 @@ static int smack_inode_getsecurity(const struct inode *inode, > > if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) { > isp = smk_of_inode(inode); > - ilen = strlen(isp) + 1; > + ilen = strlen(isp); > *buffer = isp; > return ilen; > } > @@ -1101,7 +1101,7 @@ static int smack_inode_getsecurity(const struct inode *inode, > else > return -EOPNOTSUPP; > > - ilen = strlen(isp) + 1; > + ilen = strlen(isp); > if (rc == 0) { > *buffer = isp; > rc = ilen;