RDMA/uverbs: Expand primary and alt AV port checks

The commit cited below checked that the port numbers provided in the
primary and alt AVs are legal.

That is sufficient to prevent a kernel panic. However, it is not
sufficient for correct operation.

In Linux, AVs (both primary and alt) must be completely self-described.
We do not accept an AV from userspace without an embedded port number.
(This has been the case since kernel 3.14 commit dbf727de74
("IB/core: Use GID table in AH creation and dmac resolution")).

For the primary AV, this embedded port number must match the port number
specified with IB_QP_PORT.

We also expect the port number embedded in the alt AV to match the
alt_port_num value passed by the userspace driver in the modify_qp command
base structure.

Add these checks to modify_qp.

Cc: <stable@vger.kernel.org> # 4.16
Fixes: 5d4c05c3ee ("RDMA/uverbs: Sanitize user entered port numbers prior to access it")
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/uverbs_cmd.c

@@ -1984,15 +1984,64 @@ static int modify_qp(struct ib_uverbs_file *file,
 		goto release_qp;
 	}
 
-	if ((cmd->base.attr_mask & IB_QP_AV) &&
-	    !rdma_is_port_valid(qp->device, cmd->base.dest.port_num)) {
-		ret = -EINVAL;
-		goto release_qp;
+	if ((cmd->base.attr_mask & IB_QP_AV)) {
+		if (!rdma_is_port_valid(qp->device, cmd->base.dest.port_num)) {
+			ret = -EINVAL;
+			goto release_qp;
+		}
+
+		if (cmd->base.attr_mask & IB_QP_STATE &&
+		    cmd->base.qp_state == IB_QPS_RTR) {
+		/* We are in INIT->RTR TRANSITION (if we are not,
+		 * this transition will be rejected in subsequent checks).
+		 * In the INIT->RTR transition, we cannot have IB_QP_PORT set,
+		 * but the IB_QP_STATE flag is required.
+		 *
+		 * Since kernel 3.14 (commit dbf727de7440), the uverbs driver,
+		 * when IB_QP_AV is set, has required inclusion of a valid
+		 * port number in the primary AV. (AVs are created and handled
+		 * differently for infiniband and ethernet (RoCE) ports).
+		 *
+		 * Check the port number included in the primary AV against
+		 * the port number in the qp struct, which was set (and saved)
+		 * in the RST->INIT transition.
+		 */
+			if (cmd->base.dest.port_num != qp->real_qp->port) {
+				ret = -EINVAL;
+				goto release_qp;
+			}
+		} else {
+		/* We are in SQD->SQD. (If we are not, this transition will
+		 * be rejected later in the verbs layer checks).
+		 * Check for both IB_QP_PORT and IB_QP_AV, these can be set
+		 * together in the SQD->SQD transition.
+		 *
+		 * If only IP_QP_AV was set, add in IB_QP_PORT as well (the
+		 * verbs layer driver does not track primary port changes
+		 * resulting from path migration. Thus, in SQD, if the primary
+		 * AV is modified, the primary port should also be modified).
+		 *
+		 * Note that in this transition, the IB_QP_STATE flag
+		 * is not allowed.
+		 */
+			if (((cmd->base.attr_mask & (IB_QP_AV | IB_QP_PORT))
+			     == (IB_QP_AV | IB_QP_PORT)) &&
+			    cmd->base.port_num != cmd->base.dest.port_num) {
+				ret = -EINVAL;
+				goto release_qp;
+			}
+			if ((cmd->base.attr_mask & (IB_QP_AV | IB_QP_PORT))
+			    == IB_QP_AV) {
+				cmd->base.attr_mask |= IB_QP_PORT;
+				cmd->base.port_num = cmd->base.dest.port_num;
+			}
+		}
 	}
 
 	if ((cmd->base.attr_mask & IB_QP_ALT_PATH) &&
 	    (!rdma_is_port_valid(qp->device, cmd->base.alt_port_num) ||
-	    !rdma_is_port_valid(qp->device, cmd->base.alt_dest.port_num))) {
+	    !rdma_is_port_valid(qp->device, cmd->base.alt_dest.port_num) ||
+	    cmd->base.alt_port_num != cmd->base.alt_dest.port_num)) {
 		ret = -EINVAL;
 		goto release_qp;
 	}