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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 D2690C433FF for ; Wed, 14 Aug 2019 11:00:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9EA26206C1 for ; Wed, 14 Aug 2019 11:00:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9EA26206C1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2538D6B0005; Wed, 14 Aug 2019 07:00:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1DF536B0006; Wed, 14 Aug 2019 07:00:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0A51F6B0007; Wed, 14 Aug 2019 07:00:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0241.hostedemail.com [216.40.44.241]) by kanga.kvack.org (Postfix) with ESMTP id D7CC46B0005 for ; Wed, 14 Aug 2019 07:00:29 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 8178A4859 for ; Wed, 14 Aug 2019 11:00:29 +0000 (UTC) X-FDA: 75820739778.28.form25_3e6f0ecc17b1b X-HE-Tag: form25_3e6f0ecc17b1b X-Filterd-Recvd-Size: 6172 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Wed, 14 Aug 2019 11:00:28 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 3537FADEF; Wed, 14 Aug 2019 11:00:26 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 81D741E4200; Wed, 14 Aug 2019 13:00:22 +0200 (CEST) Date: Wed, 14 Aug 2019 13:00:22 +0200 From: Jan Kara To: Mark Salyzyn Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, Tyler Hicks , Dominique Martinet , "David S. Miller" , Mathieu Malaterre , Andreas Dilger , devel@driverdev.osuosl.org, Vyacheslav Dubeyko , Joel Becker , Mark Fasheh , Chris Mason , Artem Bityutskiy , Eric Van Hensbergen , Ernesto =?iso-8859-1?Q?A=2E_Fern=E1ndez?= , Ilya Dryomov , Hugh Dickins , Serge Hallyn , Trond Myklebust , Gao Xiang , Chao Yu , David Woodhouse , Adrian Hunter , Latchesar Ionkov , Jaegeuk Kim , Jeff Layton , Dave Kleikamp , Tejun Heo , linux-mm@kvack.org, Andrew Morton , Joseph Qi , Mimi Zohar , Greg Kroah-Hartman , linux-afs@lists.infradead.org, linux-mtd@lists.infradead.org, devel@lists.orangefs.org, linux-erofs@lists.ozlabs.org, samba-technical@lists.samba.org, jfs-discussion@lists.sourceforge.net, linux-f2fs-devel@lists.sourceforge.net, v9fs-developer@lists.sourceforge.net, Theodore Ts'o , James Morris , Anna Schumaker , Richard Weinberger , Mike Marshall , Martin Brandenburg , "Darrick J. Wong" , ocfs2-devel@oss.oracle.com, Eric Paris , Paul Moore , Andreas Gruenbacher , cluster-devel@redhat.com, David Howells , Bob Peterson , Sage Weil , Steve French , Casey Schaufler , Phillip Lougher , David Sterba , Jan Kara , Miklos Szeredi , Josef Bacik , Stephen Smalley , ceph-devel@vger.kernel.org, ecryptfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-nfs@vger.kernel.org, linux-security-module@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-xfs@vger.kernel.org, netdev@vger.kernel.org, reiserfs-devel@vger.kernel.org, selinux@vger.kernel.org, stable@vger.kernel.org, Alexander Viro Subject: Re: [PATCH v2] Add flags option to get xattr method paired to __vfs_getxattr Message-ID: <20190814110022.GB26273@quack2.suse.cz> References: <20190813145527.26289-1-salyzyn@android.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190813145527.26289-1-salyzyn@android.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue 13-08-19 07:55:06, Mark Salyzyn wrote: ... > diff --git a/fs/xattr.c b/fs/xattr.c > index 90dd78f0eb27..71f887518d6f 100644 > --- a/fs/xattr.c > +++ b/fs/xattr.c ... > ssize_t > __vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name, > - void *value, size_t size) > + void *value, size_t size, int flags) > { > const struct xattr_handler *handler; > - > - handler = xattr_resolve_name(inode, &name); > - if (IS_ERR(handler)) > - return PTR_ERR(handler); > - if (!handler->get) > - return -EOPNOTSUPP; > - return handler->get(handler, dentry, inode, name, value, size); > -} > -EXPORT_SYMBOL(__vfs_getxattr); > - > -ssize_t > -vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size) > -{ > - struct inode *inode = dentry->d_inode; > int error; > > + if (flags & XATTR_NOSECURITY) > + goto nolsm; Hum, is it OK for XATTR_NOSECURITY to skip even the xattr_permission() check? I understand that for reads of security xattrs it actually does not matter in practice but conceptually that seems wrong to me as XATTR_NOSECURITY is supposed to skip just security-module checks to avoid recursion AFAIU. > diff --git a/include/uapi/linux/xattr.h b/include/uapi/linux/xattr.h > index c1395b5bd432..1216d777d210 100644 > --- a/include/uapi/linux/xattr.h > +++ b/include/uapi/linux/xattr.h > @@ -17,8 +17,9 @@ > #if __UAPI_DEF_XATTR > #define __USE_KERNEL_XATTR_DEFS > > -#define XATTR_CREATE 0x1 /* set value, fail if attr already exists */ > -#define XATTR_REPLACE 0x2 /* set value, fail if attr does not exist */ > +#define XATTR_CREATE 0x1 /* set value, fail if attr already exists */ > +#define XATTR_REPLACE 0x2 /* set value, fail if attr does not exist */ > +#define XATTR_NOSECURITY 0x4 /* get value, do not involve security check */ > #endif It seems confusing to export XATTR_NOSECURITY definition to userspace when that is kernel-internal flag. I'd just define it in include/linux/xattr.h somewhere from the top of flags space (like 0x40000000). Otherwise the patch looks OK to me (cannot really comment on the security module aspect of this whole thing though). Honza -- Jan Kara SUSE Labs, CR