hyperlight_guest/
host_functions.rs

/*
Copyright 2024 The Hyperlight Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

use alloc::format;
use alloc::string::ToString;
use alloc::vec::Vec;
use core::slice::from_raw_parts;

use hyperlight_common::flatbuffer_wrappers::function_call::FunctionCall;
use hyperlight_common::flatbuffer_wrappers::function_types::ParameterType;
use hyperlight_common::flatbuffer_wrappers::guest_error::ErrorCode;
use hyperlight_common::flatbuffer_wrappers::host_function_details::HostFunctionDetails;

use crate::error::{HyperlightGuestError, Result};
use crate::P_PEB;

pub(crate) fn validate_host_function_call(function_call: &FunctionCall) -> Result<()> {
    // get host function details
    let host_function_details = get_host_function_details();

    // check if there are any host functions
    if host_function_details.host_functions.is_none() {
        return Err(HyperlightGuestError::new(
            ErrorCode::GuestError,
            "No host functions found".to_string(),
        ));
    }

    // check if function w/ given name exists
    let host_function = if let Some(host_function) =
        host_function_details.find_by_function_name(&function_call.function_name)
    {
        host_function
    } else {
        return Err(HyperlightGuestError::new(
            ErrorCode::GuestError,
            format!(
                "Host Function Not Found: {}",
                function_call.function_name.clone()
            ),
        ));
    };

    let function_call_fparameters = if let Some(parameters) = function_call.parameters.clone() {
        parameters
    } else {
        if host_function.parameter_types.is_some() {
            return Err(HyperlightGuestError::new(
                ErrorCode::GuestError,
                format!(
                    "Incorrect parameter count for function: {}",
                    function_call.function_name.clone()
                ),
            ));
        }

        Vec::new() // if no parameters (and no mismatches), return empty vector
    };

    let function_call_parameter_types = function_call_fparameters
        .iter()
        .map(|p| p.into())
        .collect::<Vec<ParameterType>>();

    // Verify that the function call has the correct parameter types.
    host_function
        .verify_equal_parameter_types(&function_call_parameter_types)
        .map_err(|_| {
            HyperlightGuestError::new(
                ErrorCode::GuestError,
                format!(
                    "Incorrect parameter type for function: {}",
                    function_call.function_name.clone()
                ),
            )
        })?;

    Ok(())
}

pub fn get_host_function_details() -> HostFunctionDetails {
    let peb_ptr = unsafe { P_PEB.unwrap() };

    let host_function_details_buffer =
        unsafe { (*peb_ptr).hostFunctionDefinitions.fbHostFunctionDetails } as *const u8;
    let host_function_details_size =
        unsafe { (*peb_ptr).hostFunctionDefinitions.fbHostFunctionDetailsSize };

    let host_function_details_slice: &[u8] = unsafe {
        from_raw_parts(
            host_function_details_buffer,
            host_function_details_size as usize,
        )
    };

    host_function_details_slice
        .try_into()
        .expect("Failed to convert buffer to HostFunctionDetails")
}
hyperlight_guest/host_functions.rs

hyperlight_guest/
host_functions.rs
