| Message ID | 160129650442.480158.12085353517983890660.stgit@bahia.lan (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vhost: Don't call vq_access_ok() when using IOTLB | expand |
On Mon, Sep 28, 2020 at 02:35:04PM +0200, Greg Kurz wrote: > When the IOTLB device is enabled, the vring addresses we get from > userspace are GIOVAs. It is thus wrong to pass them to vq_access_ok() > which only takes HVAs. The IOTLB map is likely empty at this stage, > so there isn't much that can be done with these GIOVAs. Access validation > will be performed at IOTLB prefetch time anyway. > > BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1883084 > Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API") > Cc: jasowang@redhat.com > CC: stable@vger.kernel.org # 4.14+ > Signed-off-by: Greg Kurz <groug@kaod.org> Hmm I was sure the addresses are HVAs in any case ... Jason? > --- > drivers/vhost/vhost.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index b45519ca66a7..6296e33df31d 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -1509,7 +1509,10 @@ static long vhost_vring_set_addr(struct vhost_dev *d, > * If it is not, we don't as size might not have been setup. > * We will verify when backend is configured. */ > if (vq->private_data) { > - if (!vq_access_ok(vq, vq->num, > + /* If an IOTLB device is present, the vring addresses are > + * GIOVAs. Access will be validated during IOTLB prefetch. */ > + if (!vq->iotlb && > + !vq_access_ok(vq, vq->num, > (void __user *)(unsigned long)a.desc_user_addr, > (void __user *)(unsigned long)a.avail_user_addr, > (void __user *)(unsigned long)a.used_user_addr)) >
On Mon, Sep 28, 2020 at 02:35:04PM +0200, Greg Kurz wrote: > When the IOTLB device is enabled, the vring addresses we get from > userspace are GIOVAs. It is thus wrong to pass them to vq_access_ok() > which only takes HVAs. The IOTLB map is likely empty at this stage, > so there isn't much that can be done with these GIOVAs. Access validation > will be performed at IOTLB prefetch time anyway. > > BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1883084 > Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API") > Cc: jasowang@redhat.com > CC: stable@vger.kernel.org # 4.14+ > Signed-off-by: Greg Kurz <groug@kaod.org> > --- > drivers/vhost/vhost.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index b45519ca66a7..6296e33df31d 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -1509,7 +1509,10 @@ static long vhost_vring_set_addr(struct vhost_dev *d, > * If it is not, we don't as size might not have been setup. > * We will verify when backend is configured. */ > if (vq->private_data) { > - if (!vq_access_ok(vq, vq->num, > + /* If an IOTLB device is present, the vring addresses are > + * GIOVAs. Access will be validated during IOTLB prefetch. */ > + if (!vq->iotlb && > + !vq_access_ok(vq, vq->num, > (void __user *)(unsigned long)a.desc_user_addr, > (void __user *)(unsigned long)a.avail_user_addr, > (void __user *)(unsigned long)a.used_user_addr)) OK I think you are right here. Jason, can you ack pls? However, I think a cleaner way to check this is by moving the following check from vhost_vq_access_ok to vq_access_ok: /* Access validation occurs at prefetch time with IOTLB */ if (vq->iotlb) return true; >
On Tue, 29 Sep 2020 03:45:28 -0400 "Michael S. Tsirkin" <mst@redhat.com> wrote: > On Mon, Sep 28, 2020 at 02:35:04PM +0200, Greg Kurz wrote: > > When the IOTLB device is enabled, the vring addresses we get from > > userspace are GIOVAs. It is thus wrong to pass them to vq_access_ok() > > which only takes HVAs. The IOTLB map is likely empty at this stage, > > so there isn't much that can be done with these GIOVAs. Access validation > > will be performed at IOTLB prefetch time anyway. > > > > BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1883084 > > Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API") > > Cc: jasowang@redhat.com > > CC: stable@vger.kernel.org # 4.14+ > > Signed-off-by: Greg Kurz <groug@kaod.org> > > --- > > drivers/vhost/vhost.c | 5 ++++- > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > > index b45519ca66a7..6296e33df31d 100644 > > --- a/drivers/vhost/vhost.c > > +++ b/drivers/vhost/vhost.c > > @@ -1509,7 +1509,10 @@ static long vhost_vring_set_addr(struct vhost_dev *d, > > * If it is not, we don't as size might not have been setup. > > * We will verify when backend is configured. */ > > if (vq->private_data) { > > - if (!vq_access_ok(vq, vq->num, > > + /* If an IOTLB device is present, the vring addresses are > > + * GIOVAs. Access will be validated during IOTLB prefetch. */ > > + if (!vq->iotlb && > > + !vq_access_ok(vq, vq->num, > > (void __user *)(unsigned long)a.desc_user_addr, > > (void __user *)(unsigned long)a.avail_user_addr, > > (void __user *)(unsigned long)a.used_user_addr)) > > OK I think you are right here. > > Jason, can you ack pls? > > However, I think a cleaner way to check this is by moving > the following check from vhost_vq_access_ok to vq_access_ok: > > /* Access validation occurs at prefetch time with IOTLB */ > if (vq->iotlb) > return true; > Yes I agree. I'll do that in v2. > > > >
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index b45519ca66a7..6296e33df31d 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1509,7 +1509,10 @@ static long vhost_vring_set_addr(struct vhost_dev *d, * If it is not, we don't as size might not have been setup. * We will verify when backend is configured. */ if (vq->private_data) { - if (!vq_access_ok(vq, vq->num, + /* If an IOTLB device is present, the vring addresses are + * GIOVAs. Access will be validated during IOTLB prefetch. */ + if (!vq->iotlb && + !vq_access_ok(vq, vq->num, (void __user *)(unsigned long)a.desc_user_addr, (void __user *)(unsigned long)a.avail_user_addr, (void __user *)(unsigned long)a.used_user_addr))
When the IOTLB device is enabled, the vring addresses we get from userspace are GIOVAs. It is thus wrong to pass them to vq_access_ok() which only takes HVAs. The IOTLB map is likely empty at this stage, so there isn't much that can be done with these GIOVAs. Access validation will be performed at IOTLB prefetch time anyway. BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1883084 Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API") Cc: jasowang@redhat.com CC: stable@vger.kernel.org # 4.14+ Signed-off-by: Greg Kurz <groug@kaod.org> --- drivers/vhost/vhost.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)