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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 22 Mar 2019 21:43:42 -0000 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x2MLhojT40632570 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 22 Mar 2019 21:43:51 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D5F3452050; Fri, 22 Mar 2019 21:43:50 +0000 (GMT) Received: from rapoport-lnx (unknown [9.148.206.23]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTPS id 27A275204E; Fri, 22 Mar 2019 21:43:49 +0000 (GMT) Date: Fri, 22 Mar 2019 23:43:47 +0200 From: Mike Rapoport To: Peter Xu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Hildenbrand , Hugh Dickins , Maya Gokhale , Jerome Glisse , Pavel Emelyanov , Johannes Weiner , Martin Cracauer , Shaohua Li , Andrea Arcangeli , Mike Kravetz , Denis Plotnikov , Mike Rapoport , Marty McFadden , Mel Gorman , "Kirill A . Shutemov" , "Dr . David Alan Gilbert" Subject: Re: [PATCH v3 26/28] userfaultfd: wp: declare _UFFDIO_WRITEPROTECT conditionally References: <20190320020642.4000-1-peterx@redhat.com> <20190320020642.4000-27-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190320020642.4000-27-peterx@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-TM-AS-GCONF: 00 x-cbid: 19032221-4275-0000-0000-0000031E3656 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19032221-4276-0000-0000-0000382CC3A4 Message-Id: <20190322214346.GC9303@rapoport-lnx> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-22_12:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=648 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903220153 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 Wed, Mar 20, 2019 at 10:06:40AM +0800, Peter Xu wrote: > Only declare _UFFDIO_WRITEPROTECT if the user specified > UFFDIO_REGISTER_MODE_WP and if all the checks passed. Then when the > user registers regions with shmem/hugetlbfs we won't expose the new > ioctl to them. Even with complete anonymous memory range, we'll only > expose the new WP ioctl bit if the register mode has MODE_WP. > > Signed-off-by: Peter Xu Reviewed-by: Mike Rapoport > --- > fs/userfaultfd.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > index f1f61a0278c2..7f87e9e4fb9b 100644 > --- a/fs/userfaultfd.c > +++ b/fs/userfaultfd.c > @@ -1456,14 +1456,24 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, > up_write(&mm->mmap_sem); > mmput(mm); > if (!ret) { > + __u64 ioctls_out; > + > + ioctls_out = basic_ioctls ? UFFD_API_RANGE_IOCTLS_BASIC : > + UFFD_API_RANGE_IOCTLS; > + > + /* > + * Declare the WP ioctl only if the WP mode is > + * specified and all checks passed with the range > + */ > + if (!(uffdio_register.mode & UFFDIO_REGISTER_MODE_WP)) > + ioctls_out &= ~((__u64)1 << _UFFDIO_WRITEPROTECT); > + > /* > * Now that we scanned all vmas we can already tell > * userland which ioctls methods are guaranteed to > * succeed on this range. > */ > - if (put_user(basic_ioctls ? UFFD_API_RANGE_IOCTLS_BASIC : > - UFFD_API_RANGE_IOCTLS, > - &user_uffdio_register->ioctls)) > + if (put_user(ioctls_out, &user_uffdio_register->ioctls)) > ret = -EFAULT; > } > out: > -- > 2.17.1 > -- Sincerely yours, Mike.