IB/uverbs: Add enum attribute type to ioctl() interface

Methods sometimes need to get one attribute out of a group of
pre-defined attributes. This is an enum-like behavior. Since
this is a common requirement, we add a new ENUM attribute to the
generic uverbs ioctl() layer. This attribute is embedded in methods,
like any other attributes we currently have. ENUM attributes point to
an array of standard UVERBS_ATTR_PTR_IN. The user-space encodes the
enum's attribute id in the id field and the internal PTR_IN attr id in
the enum_data.elem_id field. This ENUM attribute could be shared by
several attributes and it can get UVERBS_ATTR_SPEC_F_MANDATORY flag,
stating this attribute must be supported by the kernel, like any other
attribute.

Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 30 insertions, 9 deletions

diff --git a/drivers/infiniband/core/uverbs_ioctl.c b/drivers/infiniband/core/uverbs_ioctl.c
index 1e6bf2488584..8c93970dc8f1 100644
--- a/drivers/infiniband/core/uverbs_ioctl.c
+++ b/drivers/infiniband/core/uverbs_ioctl.c
@@ -55,14 +55,12 @@ static int uverbs_process_attr(struct ib_device *ibdev,
 			       struct ib_uverbs_attr __user *uattr_ptr)
 {
 	const struct uverbs_attr_spec *spec;
+	const struct uverbs_attr_spec *val_spec;
 	struct uverbs_attr *e;
 	const struct uverbs_object_spec *object;
 	struct uverbs_obj_attr *o_attr;
 	struct uverbs_attr *elements = attr_bundle_h->attrs;
 
-	if (uattr->reserved)
-		return -EINVAL;
-
 	if (attr_id >= attr_spec_bucket->num_attrs) {
 		if (uattr->flags & UVERBS_ATTR_F_MANDATORY)
 			return -EINVAL;
@@ -74,26 +72,46 @@ static int uverbs_process_attr(struct ib_device *ibdev,
 		return -EINVAL;
 
 	spec = &attr_spec_bucket->attrs[attr_id];
+	val_spec = spec;
 	e = &elements[attr_id];
 	e->uattr = uattr_ptr;
 
 	switch (spec->type) {
+	case UVERBS_ATTR_TYPE_ENUM_IN:
+		if (uattr->attr_data.enum_data.elem_id >= spec->enum_def.num_elems)
+			return -EOPNOTSUPP;
+
+		if (uattr->attr_data.enum_data.reserved)
+			return -EINVAL;
+
+		val_spec = &spec->enum_def.ids[uattr->attr_data.enum_data.elem_id];
+
+		/* Currently we only support PTR_IN based enums */
+		if (val_spec->type != UVERBS_ATTR_TYPE_PTR_IN)
+			return -EOPNOTSUPP;
+
+		e->ptr_attr.enum_id = uattr->attr_data.enum_data.elem_id;
+	/* fall through */
 	case UVERBS_ATTR_TYPE_PTR_IN:
 		/* Ensure that any data provided by userspace beyond the known
 		 * struct is zero. Userspace that knows how to use some future
 		 * longer struct will fail here if used with an old kernel and
 		 * non-zero content, making ABI compat/discovery simpler.
 		 */
-		if (uattr->len > spec->ptr.len &&
-		    spec->flags & UVERBS_ATTR_SPEC_F_MIN_SZ_OR_ZERO &&
-		    !uverbs_is_attr_cleared(uattr, spec->ptr.len))
+		if (uattr->len > val_spec->ptr.len &&
+		    val_spec->flags & UVERBS_ATTR_SPEC_F_MIN_SZ_OR_ZERO &&
+		    !uverbs_is_attr_cleared(uattr, val_spec->ptr.len))
 			return -EOPNOTSUPP;
 
 	/* fall through */
 	case UVERBS_ATTR_TYPE_PTR_OUT:
-		if (uattr->len < spec->ptr.min_len ||
-		    (!(spec->flags & UVERBS_ATTR_SPEC_F_MIN_SZ_OR_ZERO) &&
-		     uattr->len > spec->ptr.len))
+		if (uattr->len < val_spec->ptr.min_len ||
+		    (!(val_spec->flags & UVERBS_ATTR_SPEC_F_MIN_SZ_OR_ZERO) &&
+		     uattr->len > val_spec->ptr.len))
+			return -EINVAL;
+
+		if (spec->type != UVERBS_ATTR_TYPE_ENUM_IN &&
+		    uattr->attr_data.reserved)
 			return -EINVAL;
 
 		e->ptr_attr.data = uattr->data;
@@ -106,6 +124,9 @@ static int uverbs_process_attr(struct ib_device *ibdev,
 			return -EINVAL;
 	/* fall through */
 	case UVERBS_ATTR_TYPE_FD:
+		if (uattr->attr_data.reserved)
+			return -EINVAL;
+
 		if (uattr->len != 0 || !ucontext || uattr->data > INT_MAX)
 			return -EINVAL;