On Wed, Feb 02 2011 at 7:08pm -0500, Milan Broz <mbroz@xxxxxxxxxx> wrote: > Add DM_SECURE_DATA_FLAG which userspace can use to control > that all allocated buffers for dm-ioctl are wiped > immediatelly after use. > > The user buffer is wipes as well (we do not want to keep > and return sensitive data back to userspace if flag is set). > > Wiping is useful mainly for cryptsetup to control that key > is present in memory only on defined places and only > for time needed. > > (For crypt, key can be present in table during load ot table > status, wait and message command). > > Signed-off-by: Milan Broz <mbroz@xxxxxxxxxx> > --- > drivers/md/dm-ioctl.c | 10 ++++++++++ > include/linux/dm-ioctl.h | 12 +++++++++--- > 2 files changed, 19 insertions(+), 3 deletions(-) > > diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c > index 189c7ab..9284c38 100644 > --- a/drivers/md/dm-ioctl.c > +++ b/drivers/md/dm-ioctl.c > @@ -1518,9 +1518,16 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl **param) > if (copy_from_user(dmi, user, tmp.data_size)) > goto fail; > > + /* Wipe the user buffer so we do not return it to userspace */ > + if ((tmp.flags & DM_SECURE_DATA_FLAG) && > + clear_user(user, tmp.data_size)) > + goto fail; > + > *param = dmi; > return 0; > fail: > + if (tmp.flags & DM_SECURE_DATA_FLAG) > + memset(dmi, 0, tmp.data_size); > vfree(dmi); > return -EFAULT; > } Maybe save the result of the tmp.flags check in a bool?, e.g.: const bool wipe_buffers = !!(tmp.flags & DM_SECURE_DATA_FLAG); Not a big deal if you don't, just an idea. > @@ -1621,6 +1628,9 @@ static int ctl_ioctl(uint command, struct dm_ioctl __user *user) > if (!r && copy_to_user(user, param, param->data_size)) > r = -EFAULT; > out: > + if (param->flags & DM_SECURE_DATA_FLAG) > + memset(param, 0, param_size); > + > vfree(param); > return r; > } Extra newline at the end not necessary. Those nits aside.. Acked-by: Mike Snitzer <snitzer@xxxxxxxxxx> -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
