vhost: fix vring requests validation broken if no FD

When VHOST_USER_VRING_NOFD_MASK is set, the fd_num is 0,
so validate_msg_fds() will return error. In this case,
the negotiation of vring message between vhost user front end and
back end would fail, and as a result, vhost user link could NOT be up.

How to reproduce:
1.Run dpdk testpmd insides VM, which locates at host with ovs+dpdk.
2.Notice that inside ovs there are endless logs regarding failure to
handle VHOST_USER_SET_VRING_CALL, and link of vm could NOT be up.

Fixes: bf472259dde6 ("vhost: fix possible denial of service by leaking FDs")
Cc: stable@dpdk.org
Signed-off-by: Zhike Wang <wangzk320@163.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Tiwei Bie <tiwei.bie@intel.com>

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 90ecee1..0cfb8b7 100644 (file)
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -1563,8 +1563,10 @@ vhost_user_set_vring_call(struct virtio_net **pdev, struct VhostUserMsg *msg,
        struct virtio_net *dev = *pdev;
        struct vhost_vring_file file;
        struct vhost_virtqueue *vq;
+       int expected_fds;
 
-       if (validate_msg_fds(msg, 1) != 0)
+       expected_fds = (msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK) ? 0 : 1;
+       if (validate_msg_fds(msg, expected_fds) != 0)
                return RTE_VHOST_MSG_RESULT_ERR;
 
        file.index = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
@@ -1588,7 +1590,10 @@ static int vhost_user_set_vring_err(struct virtio_net **pdev __rte_unused,
                        struct VhostUserMsg *msg,
                        int main_fd __rte_unused)
 {
-       if (validate_msg_fds(msg, 1) != 0)
+       int expected_fds;
+
+       expected_fds = (msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK) ? 0 : 1;
+       if (validate_msg_fds(msg, expected_fds) != 0)
                return RTE_VHOST_MSG_RESULT_ERR;
 
        if (!(msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK))
@@ -1790,8 +1795,10 @@ vhost_user_set_vring_kick(struct virtio_net **pdev, struct VhostUserMsg *msg,
        struct virtio_net *dev = *pdev;
        struct vhost_vring_file file;
        struct vhost_virtqueue *vq;
+       int expected_fds;
 
-       if (validate_msg_fds(msg, 1) != 0)
+       expected_fds = (msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK) ? 0 : 1;
+       if (validate_msg_fds(msg, expected_fds) != 0)
                return RTE_VHOST_MSG_RESULT_ERR;
 
        file.index = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;