From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756034Ab2HORfF (ORCPT ); Wed, 15 Aug 2012 13:35:05 -0400 Received: from nm1-vm0.access.bullet.mail.mud.yahoo.com ([66.94.236.27]:27214 "HELO nm1-vm0.access.bullet.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1756000Ab2HORfD (ORCPT ); Wed, 15 Aug 2012 13:35:03 -0400 X-Yahoo-Newman-Id: 403200.70157.bm@smtp105.biz.mail.bf1.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: g91ktZAVM1lgXmHJozQQhMPojwHQocx1DDZLT6AApXbhQRw NumDm9swfr_CoHodZ769g6mOJ6GM5GOSTXRN5iGF7INtcdVngI4fsUELeqIR VARL8nRuXqfOkQ.mctMxm.J6mNx5YAJmWzwcwy3beL5Up5Yxd6wejsyxWwCr dFTZFILoDI5DqyNt_mcGJ5n4_Bx.L55mwgsAtTl2_a.capm_Rg3ltiRMNnPn EhupTCGBnDRrPtFKpsmIoJDSTL6zeOoyrea3B4o2e6.CVPuOUg2QVfENb5f7 jHpzbh10JyPqKITBVt9Eep.ge_ZZL2N01ig5D8w4CpziO0n.byUAYQBSszgY N1yQaWz.CDHx6lM3Fw9NZXIF2GwpcPaq_2zNDbs8WWMqeT1fj8JqXvJDBtBf eX8KrG1oFYGC_PXP3koGp01WZgLp6isSrPLPCi2IP32Wpptyf3F9baOpUh73 1VgSnEnxtQxfUatkugOwaxKDdHWLQcqxFHWmpoFst X-Yahoo-SMTP: OIJXglSswBDfgLtXluJ6wiAYv6_cnw-- Message-ID: <502BDDC2.6030502@schaufler-ca.com> Date: Wed, 15 Aug 2012 10:34:58 -0700 From: Casey Schaufler User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:14.0) Gecko/20120713 Thunderbird/14.0 MIME-Version: 1.0 To: Andy Whitcroft CC: Miklos Szeredi , viro@ZenIV.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, hch@infradead.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, nbd@openwrt.org, neilb@suse.de, hramrach@centrum.cz, jordipujolp@gmail.com, ezk@fsl.cs.sunysb.edu, ricwheeler@gmail.com, dhowells@redhat.com, hpj@urpla.net, sedat.dilek@googlemail.com, penberg@kernel.org, goran.cetusic@gmail.com, romain@orebokech.com, mszeredi@suse.cz Subject: Re: [PATCH 12/13] ovl: switch to __inode_permission() References: <1345045700-9062-1-git-send-email-miklos@szeredi.hu> <1345045700-9062-13-git-send-email-miklos@szeredi.hu> <502BD587.6090807@schaufler-ca.com> <20120815170758.GP29100@dm> In-Reply-To: <20120815170758.GP29100@dm> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/15/2012 10:07 AM, Andy Whitcroft wrote: > On Wed, Aug 15, 2012 at 09:59:51AM -0700, Casey Schaufler wrote: >> On 8/15/2012 8:48 AM, Miklos Szeredi wrote: >>> From: Andy Whitcroft >>> >>> When checking permissions on an overlayfs inode we do not take into >>> account either device cgroup restrictions nor security permissions. >>> This allows a user to mount an overlayfs layer over a restricted device >>> directory and by pass those permissions to open otherwise restricted >>> files. >> Why is this a good idea? Either you're not including enough context >> about the conditions under which this can occur, or you're suggesting >> the introduction of a trivial mechanism for bypassing all file access >> controls. This does not seem right. > It is stating that the unprotected case is how things was before this > patch switches us over to __inode_permisssions. The patch is closing > the hole indicated. Well, that's good then. Carry on. > > -apw >>> Switch over to __inode_permissions. >>> >>> Signed-off-by: Andy Whitcroft >>> Signed-off-by: Miklos Szeredi >>> --- >>> fs/overlayfs/inode.c | 12 +----------- >>> 1 files changed, 1 insertions(+), 11 deletions(-) >>> >>> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c >>> index e854720..f3a534f 100644 >>> --- a/fs/overlayfs/inode.c >>> +++ b/fs/overlayfs/inode.c >>> @@ -100,19 +100,9 @@ int ovl_permission(struct inode *inode, int mask) >>> if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) && >>> (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) >>> goto out_dput; >>> - >>> - /* >>> - * Nobody gets write access to an immutable file. >>> - */ >>> - err = -EACCES; >>> - if (IS_IMMUTABLE(realinode)) >>> - goto out_dput; >>> } >>> >>> - if (realinode->i_op->permission) >>> - err = realinode->i_op->permission(realinode, mask); >>> - else >>> - err = generic_permission(realinode, mask); >>> + err = __inode_permission(realinode, mask); >>> out_dput: >>> dput(alias); >>> return err; > -- > 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/ >