path: root/include/rdma/uverbs_ioctl.h

/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
/*
 * Copyright (c) 2017, Mellanox Technologies inc.  All rights reserved.
 */

#ifndef _UVERBS_IOCTL_
#define _UVERBS_IOCTL_

#include <rdma/uverbs_types.h>
#include <linux/uaccess.h>
#include <rdma/rdma_user_ioctl.h>
#include <rdma/ib_user_ioctl_verbs.h>
#include <rdma/ib_user_ioctl_cmds.h>

/*
 * =======================================
 *	Verbs action specifications
 * =======================================
 */

enum uverbs_attr_type {
	UVERBS_ATTR_TYPE_NA,
	UVERBS_ATTR_TYPE_PTR_IN,
	UVERBS_ATTR_TYPE_PTR_OUT,
	UVERBS_ATTR_TYPE_IDR,
	UVERBS_ATTR_TYPE_FD,
	UVERBS_ATTR_TYPE_RAW_FD,
	UVERBS_ATTR_TYPE_ENUM_IN,
	UVERBS_ATTR_TYPE_IDRS_ARRAY,
};

enum uverbs_obj_access {
	UVERBS_ACCESS_READ,
	UVERBS_ACCESS_WRITE,
	UVERBS_ACCESS_NEW,
	UVERBS_ACCESS_DESTROY
};

/* Specification of a single attribute inside the ioctl message */
/* good size 16 */
struct uverbs_attr_spec {
	u8 type;

	/*
	 * Support extending attributes by length. Allow the user to provide
	 * more bytes than ptr.len, but check that everything after is zero'd
	 * by the user.
	 */
	u8 zero_trailing:1;
	/*
	 * Valid only for PTR_IN. Allocate and copy the data inside
	 * the parser
	 */
	u8 alloc_and_copy:1;
	u8 mandatory:1;
	/* True if this is from UVERBS_ATTR_UHW */
	u8 is_udata:1;

	union {
		struct {
			/* Current known size to kernel */
			u16 len;
			/* User isn't allowed to provide something < min_len */
			u16 min_len;
		} ptr;

		struct {
			/*
			 * higher bits mean the namespace and lower bits mean
			 * the type id within the namespace.
			 */
			u16 obj_type;
			u8 access;
		} obj;

		struct {
			u8 num_elems;
		} enum_def;
	} u;

	/* This weird split lets us remove some padding */
	union {
		struct {
			/*
			 * The enum attribute can select one of the attributes
			 * contained in the ids array. Currently only PTR_IN
			 * attributes are supported in the ids array.
			 */
			const struct uverbs_attr_spec *ids;
		} enum_def;

		struct {
			/*
			 * higher bits mean the namespace and lower bits mean
			 * the type id within the namespace.
			 */
			u16				obj_type;
			u16				min_len;
			u16				max_len;
			u8				access;
		} objs_arr;
	} u2;
};

/*
 * Information about the API is loaded into a radix tree. For IOCTL we start
 * with a tuple of:
 *  object_id, attr_id, method_id
 *
 * Which is a 48 bit value, with most of the bits guaranteed to be zero. Based
 * on the current kernel support this is compressed into 16 bit key for the
 * radix tree. Since this compression is entirely internal to the kernel the
 * below limits can be revised if the kernel gains additional data.
 *
 * With 64 leafs per node this is a 3 level radix tree.
 *
 * The tree encodes multiple types, and uses a scheme where OBJ_ID,0,0 returns
 * the object slot, and OBJ_ID,METH_ID,0 and returns the method slot.
 *
 * This also encodes the tables for the write() and write() extended commands
 * using the coding
 *   OBJ_ID,UVERBS_API_METHOD_IS_WRITE,command #
 *   OBJ_ID,UVERBS_API_METHOD_IS_WRITE_EX,command_ex #
 * ie the WRITE path is treated as a special method type in the ioctl
 * framework.
 */
enum uapi_radix_data {
	UVERBS_API_NS_FLAG = 1U << UVERBS_ID_NS_SHIFT,

	UVERBS_API_ATTR_KEY_BITS = 6,
	UVERBS_API_ATTR_KEY_MASK = GENMASK(UVERBS_API_ATTR_KEY_BITS - 1, 0),
	UVERBS_API_ATTR_BKEY_LEN = (1 << UVERBS_API_ATTR_KEY_BITS) - 1,
	UVERBS_API_WRITE_KEY_NUM = 1 << UVERBS_API_ATTR_KEY_BITS,

	UVERBS_API_METHOD_KEY_BITS = 5,
	UVERBS_API_METHOD_KEY_SHIFT = UVERBS_API_ATTR_KEY_BITS,
	UVERBS_API_METHOD_KEY_NUM_CORE = 22,
	UVERBS_API_METHOD_IS_WRITE = 30 << UVERBS_API_METHOD_KEY_SHIFT,
	UVERBS_API_METHOD_IS_WRITE_EX = 31 << UVERBS_API_METHOD_KEY_SHIFT,
	UVERBS_API_METHOD_KEY_NUM_DRIVER =
		(UVERBS_API_METHOD_IS_WRITE >> UVERBS_API_METHOD_KEY_SHIFT) -
		UVERBS_API_METHOD_KEY_NUM_CORE,
	UVERBS_API_METHOD_KEY_MASK = GENMASK(
		UVERBS_API_METHOD_KEY_BITS + UVERBS_API_METHOD_KEY_SHIFT - 1,
		UVERBS_API_METHOD_KEY_SHIFT),

	UVERBS_API_OBJ_KEY_BITS = 5,
	UVERBS_API_OBJ_KEY_SHIFT =
		UVERBS_API_METHOD_KEY_BITS + UVERBS_API_METHOD_KEY_SHIFT,
	UVERBS_API_OBJ_KEY_NUM_CORE = 20,
	UVERBS_API_OBJ_KEY_NUM_DRIVER =
		(1 << UVERBS_API_OBJ_KEY_BITS) - UVERBS_API_OBJ_KEY_NUM_CORE,
	UVERBS_API_OBJ_KEY_MASK = GENMASK(31, UVERBS_API_OBJ_KEY_SHIFT),

	/* This id guaranteed to not exist in the radix tree */
	UVERBS_API_KEY_ERR = 0xFFFFFFFF,
};

static inline __attribute_const__ u32 uapi_key_obj(u32 id)
{
	if (id & UVERBS_API_NS_FLAG) {
		id &= ~UVERBS_API_NS_FLAG;
		if (id >= UVERBS_API_OBJ_KEY_NUM_DRIVER)
			return UVERBS_API_KEY_ERR;
		id = id + UVERBS_API_OBJ_KEY_NUM_CORE;
	} else {
		if (id >= UVERBS_API_OBJ_KEY_NUM_CORE)
			return UVERBS_API_KEY_ERR;
	}

	return id << UVERBS_API_OBJ_KEY_SHIFT;
}

static inline __attribute_const__ bool uapi_key_is_object(u32 key)
{
	return (key & ~UVERBS_API_OBJ_KEY_MASK) == 0;
}

static inline __attribute_const__ u32 uapi_key_ioctl_method(u32 id)
{
	if (id & UVERBS_API_NS_FLAG) {
		id &= ~UVERBS_API_NS_FLAG;
		if (id >= UVERBS_API_METHOD_KEY_NUM_DRIVER)
			return UVERBS_API_KEY_ERR;
		id = id + UVERBS_API_METHOD_KEY_NUM_CORE;
	} else {
		id++;
		if