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[156.151.31.86]) by mx.google.com with ESMTPS id q3si1294770qtq.31.2019.04.17.12.01.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Apr 2019 12:01:31 -0700 (PDT) Received-SPF: pass (google.com: domain of darrick.wong@oracle.com designates 156.151.31.86 as permitted sender) client-ip=156.151.31.86; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2018-07-02 header.b=fRbASVPt; spf=pass (google.com: domain of darrick.wong@oracle.com designates 156.151.31.86 as permitted sender) smtp.mailfrom=darrick.wong@oracle.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x3HIwpEr168706; Wed, 17 Apr 2019 19:01:28 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=+/GWh713FqL/H8PmEw9TPiD/zMFMSIkms3hrEPjGldk=; b=fRbASVPtQ9uLksXzKdT7BQAbrdWxsanhAYsV/iNnFjPzJkzcsbIUVtK0f3snud4PKQcY aAvrPxHLjFjnYSXXe7gv2i8/14Ho+J1rHXtpyrOz+PNd8c9kUR+iKXgQ9enCCDvX5ZV4 YOIx4dQvgPaAYBex0fv/SoxMx9UUPhZliNOa+GdTupxoj/KD6jPoZ3Lmp8BM0JPemH6Y XIXg08rneLwnvKKhllhmX8kd9JbQVRMh1wvVJLWrEGjk52n5gTfDr8dk3fGAr9DyquN2 3xCZWmU1Fi/Ocm7mocv6qGokowbj75XYrLzUwWe9jkYAqX6S4TnqAVhW3j08drQMCPck Yw== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by userp2130.oracle.com with ESMTP id 2rvwk3vys7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 17 Apr 2019 19:01:27 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x3HJ116Y076328; Wed, 17 Apr 2019 19:01:27 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3030.oracle.com with ESMTP id 2ru4vtyvxy-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 17 Apr 2019 19:01:27 +0000 Received: from abhmp0020.oracle.com (abhmp0020.oracle.com [141.146.116.26]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x3HJ1QKq007212; Wed, 17 Apr 2019 19:01:26 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 17 Apr 2019 12:01:26 -0700 Date: Wed, 17 Apr 2019 12:01:24 -0700 From: "Darrick J. Wong" To: Amir Goldstein Cc: Dave Chinner , linux-xfs , Linux MM , linux-fsdevel , Ext4 , Linux Btrfs Subject: Re: [PATCH v2 4/4] xfs: don't allow most setxattr to immutable files Message-ID: <20190417190124.GA5057@magnolia> References: <155466882175.633834.15261194784129614735.stgit@magnolia> <155466884962.633834.14320700092446721044.stgit@magnolia> <20190409031929.GE5147@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9230 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904170125 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9230 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904170125 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, Apr 09, 2019 at 11:24:10AM +0300, Amir Goldstein wrote: > On Tue, Apr 9, 2019 at 6:19 AM Darrick J. Wong wrote: > > > > From: Darrick J. Wong > > > > The chattr manpage has this to say about immutable files: > > > > "A file with the 'i' attribute cannot be modified: it cannot be deleted > > or renamed, no link can be created to this file, most of the file's > > metadata can not be modified, and the file can not be opened in write > > mode." > > > > However, we don't actually check the immutable flag in the setattr code, > > which means that we can update project ids and extent size hints on > > supposedly immutable files. Therefore, reject a setattr call on an > > immutable file except for the case where we're trying to unset > > IMMUTABLE. > > > > Signed-off-by: Darrick J. Wong > > --- > > fs/xfs/xfs_ioctl.c | 46 ++++++++++++++++++++++++++++++++++++++++++++-- > > 1 file changed, 44 insertions(+), 2 deletions(-) > > > > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c > > index 5a1b96dad901..67d12027f563 100644 > > --- a/fs/xfs/xfs_ioctl.c > > +++ b/fs/xfs/xfs_ioctl.c > > @@ -1023,6 +1023,40 @@ xfs_ioctl_setattr_flush( > > return filemap_write_and_wait(inode->i_mapping); > > } > > > > +/* > > + * If immutable is set and we are not clearing it, we're not allowed to change > > + * anything else in the inode. > > This looks correct, but FYI, neither xfs_io nor chattr clears 'immutable' > and sets projid/*extsize in one ioctl/xfsctl, so there is no justification to > making an extra effort to support that use case. You could do with > checking 'immutable' inside xfs_ioctl_setattr_check_projid/*extsize() > and leave only the di_flags check here. However, the API does allow callers to clear immutable and set other fields in one go, so just because xfs_io won't do it doesn't mean we can ignore it. Then again I guess the manpage doesn't explicitly say what the behavior is supposed to be, so I guess we'll just ... argh, fine I'll go fix the manpage to document the behavior. --D > Some would say that will be cleaner code. > Its a matter of taste and its your subsystem, so feel free to dismiss > this comments. > > Thanks, > Amir. > > > Don't error out if we're only trying to set > > + * immutable on an immutable file. > > + */ > > +static int > > +xfs_ioctl_setattr_immutable( > > + struct xfs_inode *ip, > > + struct fsxattr *fa, > > + uint16_t di_flags, > > + uint64_t di_flags2) > > +{ > > + struct xfs_mount *mp = ip->i_mount; > > + > > + if (!(ip->i_d.di_flags & XFS_DIFLAG_IMMUTABLE) || > > + !(fa->fsx_xflags & FS_XFLAG_IMMUTABLE)) > > + return 0; > > + > > + if ((ip->i_d.di_flags & ~XFS_DIFLAG_IMMUTABLE) != > > + (di_flags & ~XFS_DIFLAG_IMMUTABLE)) > > + return -EPERM; > > + if (ip->i_d.di_version >= 3 && ip->i_d.di_flags2 != di_flags2) > > + return -EPERM; > > + if (xfs_get_projid(ip) != fa->fsx_projid) > > + return -EPERM; > > + if (ip->i_d.di_extsize != fa->fsx_extsize >> mp->m_sb.sb_blocklog) > > + return -EPERM; > > + if (ip->i_d.di_version >= 3 && (di_flags2 & XFS_DIFLAG2_COWEXTSIZE) && > > + ip->i_d.di_cowextsize != fa->fsx_cowextsize >> mp->m_sb.sb_blocklog) > > + return -EPERM; > > + > > + return 0; > > +} > > + > > static int > > xfs_ioctl_setattr_xflags( > > struct xfs_trans *tp, > > @@ -1030,7 +1064,9 @@ xfs_ioctl_setattr_xflags( > > struct fsxattr *fa) > > { > > struct xfs_mount *mp = ip->i_mount; > > + uint16_t di_flags; > > uint64_t di_flags2; > > + int error; > > > > /* Can't change realtime flag if any extents are allocated. */ > > if ((ip->i_d.di_nextents || ip->i_delayed_blks) && > > @@ -1061,12 +1097,18 @@ xfs_ioctl_setattr_xflags( > > !capable(CAP_LINUX_IMMUTABLE)) > > return -EPERM; > > > > - /* diflags2 only valid for v3 inodes. */ > > + /* Don't allow changes to an immutable inode. */ > > + di_flags = xfs_flags2diflags(ip, fa->fsx_xflags); > > di_flags2 = xfs_flags2diflags2(ip, fa->fsx_xflags); > > + error = xfs_ioctl_setattr_immutable(ip, fa, di_flags, di_flags2); > > + if (error) > > + return error; > > + > > + /* diflags2 only valid for v3 inodes. */ > > if (di_flags2 && ip->i_d.di_version < 3) > > return -EINVAL; > > > > - ip->i_d.di_flags = xfs_flags2diflags(ip, fa->fsx_xflags); > > + ip->i_d.di_flags = di_flags; > > ip->i_d.di_flags2 = di_flags2; > > > > xfs_diflags_to_linux(ip);