APPLEVISOR
Rust bindings for the Apple Silicon Hypervisor Framework

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Table of contents

• Getting Started
  • Self-Signed Binaries and Hypervisor Entitlement
  • Compilation Workflow
• Documentation
• Example
• Running the Tests
• Author

This library can be used to build Rust applications leveraging the Hypervisor framework on Apple Silicon.

Getting Started

Self-Signed Binaries and Hypervisor Entitlement

To be able to reach the Hypervisor Framework, a binary executable has to have been granted the hypervisor entitlement.

You can add this entitlement to a binary located at /path/to/binary by using the entitlements.xml file found at the root of the repository and the following command:

codesign --sign - --entitlements entitlements.xml --deep --force /path/to/binary

Compilation Workflow

Create a Rust project and add Applevisor as a dependency in Cargo.toml. You can either pull it from crates.io ...

# Check which version is the latest, this part of the README might not be updated
# in future releases.
applevisor = "0.1.3"

... or directly from the GitHub repository.

applevisor = { git="https://github.com/impalabs/applevisor", branch="master" }

Create a file called entitlements.txt in the project's root directory and add the following:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>com.apple.security.hypervisor</key>
    <true/>
</dict>
</plist>

Write code and then build the project.

cargo build --release

Sign the binary and grant the hypervisor entitlement.

codesign --sign - --entitlements entitlements.xml --deep --force target/release/${PROJECT_NAME}

Run the binary.

target/release/${PROJECT_NAME}

Documentation

The documentation is available online at the following address: https://docs.rs/applevisor

Alternatively, you can generate the documentation using cargo:

cargo doc --open

Example

The following example:

• creates a virtual machine for the current process;
• creates a virtual CPU;
• enables the hypervisor's debug features to be able to use breakpoints later on;
• creates a physical memory mapping of 0x1000 bytes and maps it at address 0x4000 with RWX permissions;
• writes the instructions mov x0, #0x42; brk #0; at address 0x4000;
• sets PC to 0x4000;
• starts the vCPU and runs our program;
• returns when it encounters the breakpoint.

use applevisor::*;

fn main() {
    // Creates a new virtual machine. There can be one, and only one, per process. Operations
    // on the virtual machine remains possible as long as this object is valid.
    let _vm = VirtualMachine::new().unwrap();

    // Creates a new virtual CPU. This object abstracts operations that can be performed on
    // CPUs, such as starting and stopping them, changing their registers, etc.
    let vcpu = Vcpu::new().unwrap();

    // Enables debug features for the hypervisor. This is optional, but it might be required
    // for certain features to work, such as breakpoints.
    assert!(vcpu.set_trap_debug_exceptions(true).is_ok());
    assert!(vcpu.set_trap_debug_reg_accesses(true).is_ok());

    // Creates a mapping object that represents a 0x1000-byte physical memory range.
    let mut mem = Mapping::new(0x1000).unwrap();

    // This mapping needs to be mapped to effectively allocate physical memory for the guest.
    // Here we map the region at address 0x4000 and set the permissions to Read-Write-Execute.
    assert_eq!(mem.map(0x4000, MemPerms::RWX), Ok(()));

    // Writes a `mov x0, #0x42` instruction at address 0x4000.
    assert_eq!(mem.write_dword(0x4000, 0xd2800840), Ok(4));
    // Writes a `brk #0` instruction at address 0x4004.
    assert_eq!(mem.write_dword(0x4004, 0xd4200000), Ok(4));

    // Sets PC to 0x4000.
    assert!(vcpu.set_reg(Reg::PC, 0x4000).is_ok());

    // Starts the Vcpu. It will execute our mov and breakpoint instructions before stopping.
    assert!(vcpu.run().is_ok());

    // The *exit information* can be used to used to retrieve different pieces of
    // information about the CPU exit status (e.g. exception type, fault address, etc.).
    let _exit_info = vcpu.get_exit_info();

    // If everything went as expected, the value in X0 is 0x42.
    assert_eq!(vcpu.get_reg(Reg::X0), Ok(0x42));
}

Feel free to also have a look at the Hyperpom project's source code for a real-life example of how these bindings are used.

Running the Tests

To run tests using the Makefile provided with the project, you'll first need to install jq. You can do so using brew:

brew install jq

You can then run the tests with the provided Makefile using the following command:

make tests

Author

• Maxime Peterlin - [email protected]