IB/core: Better checking of userspace values for receive flow steering

- Don't allow unsupported comp_mask values, user should check
    ibv_query_device to know which features are supported.
  - Add a check in ib_uverbs_create_flow() to verify the size passed
    from the user space.

Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/core/uverbs_cmd.c

@@ -2652,17 +2652,31 @@ ssize_t ib_uverbs_create_flow(struct ib_uverbs_file *file,
 	if (copy_from_user(&cmd, buf, sizeof(cmd)))
 		return -EFAULT;
 
+	if (cmd.comp_mask)
+		return -EINVAL;
+
 	if ((cmd.flow_attr.type == IB_FLOW_ATTR_SNIFFER &&
 	     !capable(CAP_NET_ADMIN)) || !capable(CAP_NET_RAW))
 		return -EPERM;
 
+	if (cmd.flow_attr.num_of_specs < 0 ||
+	    cmd.flow_attr.num_of_specs > IB_FLOW_SPEC_SUPPORT_LAYERS)
+		return -EINVAL;
+
+	kern_attr_size = cmd.flow_attr.size - sizeof(cmd) -
+			 sizeof(struct ib_uverbs_cmd_hdr_ex);
+
+	if (cmd.flow_attr.size < 0 || cmd.flow_attr.size > in_len ||
+	    kern_attr_size < 0 || kern_attr_size >
+	    (cmd.flow_attr.num_of_specs * sizeof(struct ib_kern_spec)))
+		return -EINVAL;
+
 	if (cmd.flow_attr.num_of_specs) {
 		kern_flow_attr = kmalloc(cmd.flow_attr.size, GFP_KERNEL);
 		if (!kern_flow_attr)
 			return -ENOMEM;
 
 		memcpy(kern_flow_attr, &cmd.flow_attr, sizeof(*kern_flow_attr));
-		kern_attr_size = cmd.flow_attr.size - sizeof(cmd) - sizeof(struct ib_uverbs_cmd_hdr_ex);
 		if (copy_from_user(kern_flow_attr + 1, buf + sizeof(cmd),
 				   kern_attr_size)) {
 			err = -EFAULT;

include/rdma/ib_verbs.h

@@ -1098,6 +1098,8 @@ enum ib_flow_spec_type {
 	IB_FLOW_SPEC_UDP	= 0x41
 };
 
+#define IB_FLOW_SPEC_SUPPORT_LAYERS 4
+
 /* Flow steering rule priority is set according to it's domain.
  * Lower domain value means higher priority.
  */