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stub(efivars): cargo fmt
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@RaitoBezarius
RaitoBezarius committed May 18, 2023
1 parent f0ef04b commit 0e22a51
Showing 1 changed file with 113 additions and 70 deletions.
183 changes: 113 additions & 70 deletions rust/stub/src/efivars.rs
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Original file line number Diff line number Diff line change
@@ -1,13 +1,31 @@
use alloc::{vec::Vec, vec, string::ToString, format};
use uefi::{Result, Handle, prelude::{BootServices, RuntimeServices}, proto::{device_path::{DevicePath, media::{HardDrive, PartitionSignature}, DeviceType, DeviceSubType, text::DevicePathToText}, loaded_image::LoadedImage}, Guid, guid, table::{runtime::{VariableVendor, VariableAttributes}, SystemTable, Boot}, cstr16, CStr16};
use alloc::{format, string::ToString, vec, vec::Vec};
use uefi::{
cstr16, guid,
prelude::{BootServices, RuntimeServices},
proto::{
device_path::{
media::{HardDrive, PartitionSignature},
text::DevicePathToText,
DevicePath, DeviceSubType, DeviceType,
},
loaded_image::LoadedImage,
},
table::{
runtime::{VariableAttributes, VariableVendor},
Boot, SystemTable,
},
CStr16, Guid, Handle, Result,
};

use bitflags::bitflags;

fn disk_get_part_uuid(boot_services: &BootServices, disk_handle: Handle) -> Result<Guid> {
let dp = boot_services.open_protocol_exclusive::<DevicePath>(disk_handle)?;

for node in dp.node_iter() {
if node.device_type() != DeviceType::MEDIA || node.sub_type() != DeviceSubType::MEDIA_HARD_DRIVE {
if node.device_type() != DeviceType::MEDIA
|| node.sub_type() != DeviceSubType::MEDIA_HARD_DRIVE
{
continue;
}

Expand All @@ -21,12 +39,12 @@ fn disk_get_part_uuid(boot_services: &BootServices, disk_handle: Handle) -> Resu
Err(uefi::Status::UNSUPPORTED.into())
}


/// systemd loader's GUID
/// != systemd's GUID
/// https://github.com/systemd/systemd/blob/main/src/boot/efi/util.h#L114-L121
/// https://systemd.io/BOOT_LOADER_INTERFACE/
pub const BOOT_LOADER_VENDOR_UUID: VariableVendor = VariableVendor(guid!("4a67b082-0a4c-41cf-b6c7-440b29bb8c4f"));
pub const BOOT_LOADER_VENDOR_UUID: VariableVendor =
VariableVendor(guid!("4a67b082-0a4c-41cf-b6c7-440b29bb8c4f"));

/// Lanzaboote stub name
pub static STUB_INFO_STRING: &str = concat!("lanzastub ", env!("CARGO_PKG_VERSION"));
Expand Down Expand Up @@ -54,19 +72,22 @@ bitflags! {
/// Get the currently supported EFI features from the loader if they do exist
/// https://systemd.io/BOOT_LOADER_INTERFACE/
pub fn get_loader_features(runtime_services: &RuntimeServices) -> Result<EfiLoaderFeatures> {
if let Ok(size) = runtime_services.get_variable_size(cstr16!("LoaderFeatures"), &BOOT_LOADER_VENDOR_UUID) {
if let Ok(size) =
runtime_services.get_variable_size(cstr16!("LoaderFeatures"), &BOOT_LOADER_VENDOR_UUID)
{
let mut buffer = vec![0; size].into_boxed_slice();
runtime_services.get_variable(
cstr16!("LoaderFeatures"),
&BOOT_LOADER_VENDOR_UUID,
&mut buffer)?;

return EfiLoaderFeatures::from_bits(
u64::from_le_bytes(
(*buffer).try_into()
.map_err(|_err| uefi::Status::BAD_BUFFER_SIZE)?
))
.ok_or_else(|| uefi::Status::INCOMPATIBLE_VERSION.into());
&mut buffer,
)?;

return EfiLoaderFeatures::from_bits(u64::from_le_bytes(
(*buffer)
.try_into()
.map_err(|_err| uefi::Status::BAD_BUFFER_SIZE)?,
))
.ok_or_else(|| uefi::Status::INCOMPATIBLE_VERSION.into());
}

Ok(Default::default())
Expand Down Expand Up @@ -106,21 +127,19 @@ pub fn cstr16_to_bytes(s: &CStr16) -> &[u8] {

/// Ensures that an UEFI variable is set or set it with a fallback value
/// computed in a lazy way.
pub fn ensure_efi_variable<F>(runtime_services: &RuntimeServices,
pub fn ensure_efi_variable<F>(
runtime_services: &RuntimeServices,
name: &CStr16,
vendor: &VariableVendor,
attributes: VariableAttributes,
get_fallback_value: F) -> uefi::Result
where F: FnOnce() -> uefi::Result<Vec<u8>>
get_fallback_value: F,
) -> uefi::Result
where
F: FnOnce() -> uefi::Result<Vec<u8>>,
{
// If we get a variable size, a variable already exist.
if runtime_services.get_variable_size(name, vendor).is_err() {
runtime_services.set_variable(
name,
vendor,
attributes,
&get_fallback_value()?
)?;
runtime_services.set_variable(name, vendor, attributes, &get_fallback_value()?)?;
}

uefi::Status::SUCCESS.into()
Expand All @@ -131,91 +150,115 @@ pub fn export_efi_variables(system_table: &SystemTable<Boot>) -> Result<()> {
let boot_services = system_table.boot_services();
let runtime_services = system_table.runtime_services();

let stub_features: EfiStubFeatures =
EfiStubFeatures::ReportBootPartition;
let stub_features: EfiStubFeatures = EfiStubFeatures::ReportBootPartition;

let loaded_image =
boot_services.open_protocol_exclusive::<LoadedImage>(boot_services.image_handle())?;

let default_attributes = VariableAttributes::BOOTSERVICE_ACCESS | VariableAttributes::RUNTIME_ACCESS;
let default_attributes =
VariableAttributes::BOOTSERVICE_ACCESS | VariableAttributes::RUNTIME_ACCESS;

#[allow(unused_must_use)]
// LoaderDevicePartUUID
ensure_efi_variable(runtime_services,
ensure_efi_variable(
runtime_services,
cstr16!("LoaderDevicePartUUID"),
&BOOT_LOADER_VENDOR_UUID,
default_attributes,
|| disk_get_part_uuid(boot_services, loaded_image.device()).map(|guid| guid.to_string()
.encode_utf16()
.flat_map(|c| c.to_le_bytes())
.collect::<Vec<u8>>()
)
).ok();
|| {
disk_get_part_uuid(boot_services, loaded_image.device()).map(|guid| {
guid.to_string()
.encode_utf16()
.flat_map(|c| c.to_le_bytes())
.collect::<Vec<u8>>()
})
},
)
.ok();
// LoaderImageIdentifier
ensure_efi_variable(runtime_services,
ensure_efi_variable(
runtime_services,
cstr16!("LoaderImageIdentifier"),
&BOOT_LOADER_VENDOR_UUID,
default_attributes,
|| {
if let Some(dp) = loaded_image.file_path() {
let dp_protocol = boot_services.open_protocol_exclusive::<DevicePathToText>(
boot_services.get_handle_for_protocol::<DevicePathToText>()?
boot_services.get_handle_for_protocol::<DevicePathToText>()?,
)?;
dp_protocol.convert_device_path_to_text(
boot_services,
dp,
uefi::proto::device_path::text::DisplayOnly(false),
uefi::proto::device_path::text::AllowShortcuts(false)
).map(|ps| cstr16_to_bytes(&ps).to_vec())
dp_protocol
.convert_device_path_to_text(
boot_services,
dp,
uefi::proto::device_path::text::DisplayOnly(false),
uefi::proto::device_path::text::AllowShortcuts(false),
)
.map(|ps| cstr16_to_bytes(&ps).to_vec())
} else {
// If we cannot retrieve the filepath of the loaded image
// Then, we cannot set `LoaderImageIdentifier`.
Err(uefi::Status::UNSUPPORTED.into())
}
}).ok();
},
)
.ok();
// LoaderFirmwareInfo
ensure_efi_variable(runtime_services,
ensure_efi_variable(
runtime_services,
cstr16!("LoaderFirmwareInfo"),
&BOOT_LOADER_VENDOR_UUID,
default_attributes,
|| Ok(
format!("{} {}.{:02}", system_table.firmware_vendor(), system_table.firmware_revision() >> 16, system_table.firmware_revision() & 0xFFFFF)
|| {
Ok(format!(
"{} {}.{:02}",
system_table.firmware_vendor(),
system_table.firmware_revision() >> 16,
system_table.firmware_revision() & 0xFFFFF
)
.encode_utf16()
.flat_map(|c| c.to_le_bytes())
.collect::<Vec<u8>>()
)
).ok();
.collect::<Vec<u8>>())
},
)
.ok();
// LoaderFirmwareType
ensure_efi_variable(runtime_services,
ensure_efi_variable(
runtime_services,
cstr16!("LoaderFirmwareType"),
&BOOT_LOADER_VENDOR_UUID,
default_attributes,
|| Ok(
format!("UEFI {:02}", system_table.uefi_revision())
.encode_utf16()
.flat_map(|c| c.to_le_bytes())
.collect::<Vec<u8>>()
)
).ok();
|| {
Ok(format!("UEFI {:02}", system_table.uefi_revision())
.encode_utf16()
.flat_map(|c| c.to_le_bytes())
.collect::<Vec<u8>>())
},
)
.ok();
// StubInfo
// FIXME: ideally, no one should be able to overwrite `StubInfo`, but that would require
// constructing an EFI authenticated variable payload. This seems overcomplicated for now.
runtime_services.set_variable(
cstr16!("StubInfo"),
&BOOT_LOADER_VENDOR_UUID,
default_attributes,
&STUB_INFO_STRING.encode_utf16().flat_map(|c| c.to_le_bytes()).collect::<Vec<u8>>()
).ok();
runtime_services
.set_variable(
cstr16!("StubInfo"),
&BOOT_LOADER_VENDOR_UUID,
default_attributes,
&STUB_INFO_STRING
.encode_utf16()
.flat_map(|c| c.to_le_bytes())
.collect::<Vec<u8>>(),
)
.ok();

// StubFeatures
runtime_services.set_variable(
cstr16!("StubFeatures"),
&BOOT_LOADER_VENDOR_UUID,
default_attributes,
&stub_features.bits().to_le_bytes()
).ok();
runtime_services
.set_variable(
cstr16!("StubFeatures"),
&BOOT_LOADER_VENDOR_UUID,
default_attributes,
&stub_features.bits().to_le_bytes(),
)
.ok();

Ok(())
}


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