# EFI Resolver
Author: **Vector 35 Inc**

_A Binary Ninja built-in plugin that automatically resolves type information for EFI protocol usage._

## Description:

EFI Resolver is a Binary Ninja plugin that automates the resolution of EFI protocol type information. It supports both
DXE files and PEI modules. The plugin propagates parameter pointers from entry points to system tables, including the
main system table, MM system table, boot services, and runtime services, assigning types to global variables.

For PEI files, EFI Resolver can also detect
[processor-specific patterns](https://uefi.org/specs/PI/1.8/V1_PEI_Foundation.html#pei-services-table-retrieval)
used to retrieve PEI services pointers.

Additionally, the plugin identifies references to boot services, MM protocol functions, and PEI services. It applies
type information based on the GUIDs passed to these functions.

EFI Resolver supports the core UEFI specification and allows users to define custom vendor protocols.

## Build Instructions

```bash
git clone https://github.com/Vector35/binaryninja-api.git && cd binaryninja-api/plugins/efi_resolver
export BN_API_PATH=../binaryninja-api # Or specifying the path to api repo
cmake -S . -B build -GNinja
cmake --build build -t install
```

## License

This plugin is released under an Apache-2.0 license.

## Supplying Custom UEFI Protocol GUIDs and Types

EFI Resolver propagates types and GUIDs using Binary Ninja's native platform types for EFI. Many UEFI
firmware binaries include types (and GUIDs) for proprietary protocols. This section describes how users can supply
custom UEFI types and GUIDs for use with EFI Resolver type propagation.

### User-supplied EFI GUIDs

EFI Resolver uses a JSON file to associate user-supplied EFI GUIDs with types for propagation. GUIDs for proprietary
protocol types can be used with EFI Resolver by creating a file at `<user folder>/types/efi-guids.json` containing JSON
entries in the following format:

```json
{
  "EFI_EXAMPLE_CUSTOM_PROTOCOL_GUID": [
    19088743,
    35243,
    52719,
    1,
    35,
    69,
    103,
    137,
    171,
    205,
    239
 ]
}
```

In this example, the protocol type of `EFI_EXAMPLE_CUSTOM_PROTOCOL` is mapped to the
`{0x01234567,0x89ab,0xcdef,{0x01,0x23,0x45,0x67,0x89,0xab,0xcd,0xef}}` GUID (named `EFI_EXAMPLE_CUSTOM_PROTOCOL_GUID`).
To test that the file is a valid JSON file, run `python -m json.tool < efi-guids.json`.

__Note: user-supplied proprietary GUIDs from `efi-guids.json` are used to name variables regardless of whether or not an associated platform type has been loaded. If EFI Resolver fails to query the type for an EFI protocol interface, it will set the variable type for the protocol interface pointer to `VOID*`.__

### User-supplied EFI Platform Types

Types and structures for proprietary protocols are to be imported using Binary Ninja's standard mechanism for loading
user-supplied platform types. Instructions on adding custom platform types can be found [here](https://docs.binary.ninja/guide/types/platformtypes.html). Available EFI platform names include:
- `efi-x86`
- `efi-x86_64`
- `efi-thumb2`
- `efi-armv7`
- `efi-aarch64`
- `efi-windows-aarch64`
- `efi-windows-x86`
- `efi-windows-x86_64`

To avoid having to add duplicate types in each platform-specific `*.c` file, it is recommended to add common types
to a top-level `efi.c` file and `#include` the file in the platform-specific `*.c` files. For example:

```C
// <user folder>/types/platform/efi-x86_64.c including <user folder>/types/efi.c
#include "../efi.c"
```

To test that C source files containing custom EFI platform types are in the correct format, use the `bv.platform.parse_types_from_source_file` API.

Alternatively, user types can be supplied manually from type libraries, header files, or any other mechanism supported
by Binary Ninja. Just ensure that the name for types associated with GUIDs match what is in `efi-guids.json`. Protocol
GUID names in `efi-guids.json` should end with `_PROTOCOL_GUID` and the prefix must be identical to the associated
protocol type name. For example, if the GUID is named `EFI_EXAMPLE_PROTOCOL_GUID`, EFI Resolver will attempt to
look up a type named `EFI_EXAMPLE_PROTOCOL`.

### Full Example

In summary, including a custom platform type of `EFI_EXAMPLE_CUSTOM_PROTOCOL` for the `efi-x86` platform and associating
it with a GUID named `EFI_EXAMPLE_CUSTOM_PROTOCOL_GUID` requires two steps:

1. Create the `<user folder>/types/platform/efi-x86.c` header file:

```C
struct EFI_EXAMPLE_CUSTOM_PROTOCOL
{
    uint32_t length;
}
```

2. Create the `<user folder>/types/efi-guids.json` file:

```json
{
    "EFI_EXAMPLE_CUSTOM_PROTOCOL_GUID": [
      19088743,
      35243,
      52719,
      1,
      35,
      69,
      103,
      137,
      171,
      205,
      239
    ]
}
```

After a Binary Ninja restart, when a binary is loaded with the `efi-x86` platform, the `EFI_EXAMPLE_CUSTOM_PROTOCOL`
type will be imported. When EFI Resolver runs, it will detect uses of `EFI_EXAMPLE_CUSTOM_PROTOCOL_GUID` and propagate
the `EFI_EXAMPLE_CUSTOM_PROTOCOL` type.