On Thu, Jan 04, 2018 at 07:14:54AM -0800, Carlos Cardenas wrote:
> Mike Larkin <mlar...@azathoth.net> wrote:
>
> > On Wed, Jan 03, 2018 at 08:03:56PM -0800, Carlos Cardenas wrote:
> > > Howdy.
> > >
> > > Attached is a patch to address a TOCTOU issue with checking to
> > > ensure disks are regular files, reported by jca@ .
> > >
> > > Comments? Ok?
> > >
> > > +--+
> > > Carlos
> >
> > > Index: config.c
> > > ===================================================================
> > > RCS file: /home/los/cvs/src/usr.sbin/vmd/config.c,v
> > > retrieving revision 1.38
> > > diff -u -p -a -u -r1.38 config.c
> > > --- config.c 3 Jan 2018 05:39:56 -0000 1.38
> > > +++ config.c 4 Jan 2018 03:55:47 -0000
> > > @@ -262,23 +262,23 @@ config_setvm(struct privsep *ps, struct
> > > /* Open disk images for child */
> > > for (i = 0 ; i < vcp->vcp_ndisks; i++) {
> > > /* Stat disk[i] to ensure it is a regular file */
> > > - if (stat(vcp->vcp_disks[i], &stat_buf) == -1) {
> > > + if ((diskfds[i] =
> > > + open(vcp->vcp_disks[i], O_RDWR)) == -1) {
> >
> > O_RDONLY? Or do we actually support the SCSI write commands (ala
> > writing ISO images?)
>
> vcp_disks represent the vioblk devices which are RDWR.
> vcp_cdrom is RDONLY since it doesn't support writing ISOs.
>
Of course. I missed that bit. You're right. I thought this was only for
the recent cdrom changes. No concern then.
> >
> > > log_warn("%s: can't open disk %s", __func__,
> > > vcp->vcp_disks[i]);
> > > errno = VMD_DISK_MISSING;
> > > goto fail;
> > > }
> > > - if (S_ISREG(stat_buf.st_mode) == 0) {
> > > - log_warn("%s: disk %s is not a regular file", __func__,
> > > + if (fstat(diskfds[i], &stat_buf) == -1) {
> > > + log_warn("%s: can't open disk %s", __func__,
> > > vcp->vcp_disks[i]);
> > > - errno = VMD_DISK_INVALID;
> > > + errno = VMD_DISK_MISSING;
> >
> > I'd probably stick with INVALID here since technically the image is not
> > really "missing"
>
> Makes sense.
>
> >
> > > goto fail;
> > > }
> > > - if ((diskfds[i] =
> > > - open(vcp->vcp_disks[i], O_RDWR)) == -1) {
> > > - log_warn("%s: can't open disk %s", __func__,
> > > + if (S_ISREG(stat_buf.st_mode) == 0) {
> > > + log_warn("%s: disk %s is not a regular file", __func__,
> > > vcp->vcp_disks[i]);
> > > - errno = VMD_DISK_MISSING;
> > > + errno = VMD_DISK_INVALID;
> > > goto fail;
> > > }
> > > }
> >
> > ok mlarkin otherwise
