static int cxl_validate_cmd_from_user()

in core/mbox.c [229:319]

• 49 lines of code
• 18 McCabe index (conditional complexity)

static int cxl_validate_cmd_from_user(struct cxl_dev_state *cxlds,
				      const struct cxl_send_command *send_cmd,
				      struct cxl_mem_command *out_cmd)
{
	const struct cxl_command_info *info;
	struct cxl_mem_command *c;

	if (send_cmd->id == 0 || send_cmd->id >= CXL_MEM_COMMAND_ID_MAX)
		return -ENOTTY;

	/*
	 * The user can never specify an input payload larger than what hardware
	 * supports, but output can be arbitrarily large (simply write out as
	 * much data as the hardware provides).
	 */
	if (send_cmd->in.size > cxlds->payload_size)
		return -EINVAL;

	/*
	 * Checks are bypassed for raw commands but a WARN/taint will occur
	 * later in the callchain
	 */
	if (send_cmd->id == CXL_MEM_COMMAND_ID_RAW) {
		const struct cxl_mem_command temp = {
			.info = {
				.id = CXL_MEM_COMMAND_ID_RAW,
				.flags = 0,
				.size_in = send_cmd->in.size,
				.size_out = send_cmd->out.size,
			},
			.opcode = send_cmd->raw.opcode
		};

		if (send_cmd->raw.rsvd)
			return -EINVAL;

		/*
		 * Unlike supported commands, the output size of RAW commands
		 * gets passed along without further checking, so it must be
		 * validated here.
		 */
		if (send_cmd->out.size > cxlds->payload_size)
			return -EINVAL;

		if (!cxl_mem_raw_command_allowed(send_cmd->raw.opcode))
			return -EPERM;

		memcpy(out_cmd, &temp, sizeof(temp));

		return 0;
	}

	if (send_cmd->flags & ~CXL_MEM_COMMAND_FLAG_MASK)
		return -EINVAL;

	if (send_cmd->rsvd)
		return -EINVAL;

	if (send_cmd->in.rsvd || send_cmd->out.rsvd)
		return -EINVAL;

	/* Convert user's command into the internal representation */
	c = &cxl_mem_commands[send_cmd->id];
	info = &c->info;

	/* Check that the command is enabled for hardware */
	if (!test_bit(info->id, cxlds->enabled_cmds))
		return -ENOTTY;

	/* Check that the command is not claimed for exclusive kernel use */
	if (test_bit(info->id, cxlds->exclusive_cmds))
		return -EBUSY;

	/* Check the input buffer is the expected size */
	if (info->size_in >= 0 && info->size_in != send_cmd->in.size)
		return -ENOMEM;

	/* Check the output buffer is at least large enough */
	if (info->size_out >= 0 && send_cmd->out.size < info->size_out)
		return -ENOMEM;

	memcpy(out_cmd, c, sizeof(*c));
	out_cmd->info.size_in = send_cmd->in.size;
	/*
	 * XXX: out_cmd->info.size_out will be controlled by the driver, and the
	 * specified number of bytes @send_cmd->out.size will be copied back out
	 * to userspace.
	 */

	return 0;
}