IB/uverbs: Add PTR_IN attributes that are allocated/copied automatically

Adding UVERBS_ATTR_SPEC_F_ALLOC_AND_COPY flag to PTR_IN attributes.
By using this flag, the parse automatically allocates and copies the
user-space data. This data is accessible by using uverbs_attr_get_len
and uverbs_attr_get_alloced_ptr inline accessor functions from the
handler.
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/uverbs_ioctl.c

@@ -114,9 +114,27 @@ static int uverbs_process_attr(struct ib_device *ibdev,
 		    uattr->attr_data.reserved)
 			return -EINVAL;
 
-		e->ptr_attr.data = uattr->data;
 		e->ptr_attr.len = uattr->len;
 		e->ptr_attr.flags = uattr->flags;
+
+		if (val_spec->flags & UVERBS_ATTR_SPEC_F_ALLOC_AND_COPY &&
+		    !uverbs_attr_ptr_is_inline(e)) {
+			void *p;
+
+			p = kvmalloc(uattr->len, GFP_KERNEL);
+			if (!p)
+				return -ENOMEM;
+
+			e->ptr_attr.ptr = p;
+
+			if (copy_from_user(p, u64_to_user_ptr(uattr->data),
+					   uattr->len)) {
+				kvfree(p);
+				return -EFAULT;
+			}
+		} else {
+			e->ptr_attr.data = uattr->data;
+		}
 		break;
 
 	case UVERBS_ATTR_TYPE_IDR:
@@ -200,6 +218,11 @@ static int uverbs_finalize_attrs(struct uverbs_attr_bundle *attrs_bundle,
 					spec->obj.access, commit);
 				if (!ret)
 					ret = current_ret;
+			} else if (spec->type == UVERBS_ATTR_TYPE_PTR_IN &&
+				   spec->flags &
+					   UVERBS_ATTR_SPEC_F_ALLOC_AND_COPY &&
+				   !uverbs_attr_ptr_is_inline(attr)) {
+				kvfree(attr->ptr_attr.ptr);
 			}
 		}
 	}

include/rdma/uverbs_ioctl.h

@@ -65,6 +65,10 @@ enum {
 	UVERBS_ATTR_SPEC_F_MANDATORY	= 1U << 0,
 	/* Support extending attributes by length, validate all unknown size == zero  */
 	UVERBS_ATTR_SPEC_F_MIN_SZ_OR_ZERO = 1U << 1,
+	/*
+	 * Valid only for PTR_IN. Allocate and copy the data inside the parser
+	 */
+	UVERBS_ATTR_SPEC_F_ALLOC_AND_COPY = 1U << 2,
 };
 
 /* Specification of a single attribute inside the ioctl message */
@@ -323,7 +327,14 @@ struct uverbs_object_tree_def {
  */
 
 struct uverbs_ptr_attr {
+	/*
+	 * If UVERBS_ATTR_SPEC_F_ALLOC_AND_COPY is set then the 'ptr' is
+	 * used.
+	 */
+	union {
+		void *ptr;
 		u64 data;
+	};
 	u16		len;
 	/* Combination of bits from enum UVERBS_ATTR_F_XXXX */
 	u16		flags;
@@ -431,6 +442,17 @@ static inline struct ib_uobject *uverbs_attr_get_uobject(const struct uverbs_att
 	return attr->obj_attr.uobject;
 }
 
+static inline int
+uverbs_attr_get_len(const struct uverbs_attr_bundle *attrs_bundle, u16 idx)
+{
+	const struct uverbs_attr *attr = uverbs_attr_get(attrs_bundle, idx);
+
+	if (IS_ERR(attr))
+		return PTR_ERR(attr);
+
+	return attr->ptr_attr.len;
+}
+
 static inline int uverbs_copy_to(const struct uverbs_attr_bundle *attrs_bundle,
 				 size_t idx, const void *from, size_t size)
 {
@@ -457,6 +479,18 @@ static inline bool uverbs_attr_ptr_is_inline(const struct uverbs_attr *attr)
 	return attr->ptr_attr.len <= sizeof(attr->ptr_attr.data);
 }
 
+static inline void *uverbs_attr_get_alloced_ptr(
+	const struct uverbs_attr_bundle *attrs_bundle, u16 idx)
+{
+	const struct uverbs_attr *attr = uverbs_attr_get(attrs_bundle, idx);
+
+	if (IS_ERR(attr))
+		return (void *)attr;
+
+	return uverbs_attr_ptr_is_inline(attr) ? (void *)&attr->ptr_attr.data :
+						 attr->ptr_attr.ptr;
+}
+
 static inline int _uverbs_copy_from(void *to,
 				    const struct uverbs_attr_bundle *attrs_bundle,
 				    size_t idx,