stub: split up into a linux-bootloader crate

We introduce `linux-bootloader` a crate made to build Rust-based Linux-oriented bootloaders.

It follows systemd/UAPI group and semantics as much as possible, e.g. BLS/loader capabilities/stub capabilities.

rust/linux-bootloader/Cargo.lock

@@ -0,0 +1,193 @@
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+# It is not intended for manual editing.
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+
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+dependencies = [
+ "log",
+ "plain",
+ "scroll",
+]
+
+[[package]]
+name = "linux-bootloader"
+version = "0.3.0"
+dependencies = [
+ "bitflags",
+ "goblin",
+ "log",
+ "sha1_smol",
+ "uefi",
+]
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+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
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+ "proc-macro2",
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+checksum = "04c565b551bafbef4157586fa379538366e4385d42082f255bfd96e4fe8519da"
+dependencies = [
+ "scroll_derive",
+]
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.27",
+]
+
+[[package]]
+name = "sha1_smol"
+version = "1.0.0"
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+checksum = "ae1a47186c03a32177042e55dbc5fd5aee900b8e0069a8d70fba96a9375cd012"
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.27"
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+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
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+dependencies = [
+ "bit_field",
+]
+
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+dependencies = [
+ "bitflags",
+ "log",
+ "ptr_meta",
+ "ucs2",
+ "uefi-macros",
+ "uefi-raw",
+ "uguid",
+]
+
+[[package]]
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+ "proc-macro2",
+ "quote",
+ "syn 2.0.27",
+]
+
+[[package]]
+name = "uefi-raw"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
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+dependencies = [
+ "bitflags",
+ "ptr_meta",
+ "uguid",
+]
+
+[[package]]
+name = "uguid"
+version = "2.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
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rust/linux-bootloader/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "linux-bootloader"
+version = "0.3.0"
+edition = "2021"
+publish = true
+license = "GPL-3.0-only"
+keywords = ["osdev", "linux", "bootloader"]
+categories = ["embedded", "hardware-support", "no-std", "os::linux-apis"]
+description = "Utilities to build Linux-based bootloaders"
+repository = "https://github.com/nix-community/lanzaboote/"
+
+[dependencies]
+uefi = { version = "0.24.0", default-features = false, features = [ "alloc", "global_allocator" ] }
+goblin = { version = "0.6.1", default-features = false, features = [ "pe64", "alloc" ]}
+bitflags = "2.3.3"
+
+# Even in debug builds, we don't enable the debug logs, because they generate a lot of spam from goblin.
+log = { version = "0.4.19", default-features = false, features = [ "max_level_info", "release_max_level_warn" ]}
+
+# SHA1 for TPM TCG interface version 1.
+sha1_smol = "1.0.0"
+
+[badges]
+maintenance = { status = "actively-developed" }

rust/linux-bootloader/rust-toolchain.toml

@@ -0,0 +1,4 @@
+[toolchain]
+channel = "1.68.2"
+components = [ "rust-src" ]
+targets = [ "x86_64-unknown-uefi" ]

rust/linux-bootloader/src/efivars.rs

@@ -46,11 +46,7 @@ fn disk_get_part_uuid(boot_services: &BootServices, disk_handle: Handle) -> Resu
 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"));
-
 bitflags! {
-
     #[repr(transparent)]
     #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Default)]
     /// Feature flags as described in https://systemd.io/BOOT_LOADER_INTERFACE/
@@ -146,7 +142,7 @@ where
 }
 
 /// Exports systemd-stub style EFI variables
-pub fn export_efi_variables(system_table: &SystemTable<Boot>) -> Result<()> {
+pub fn export_efi_variables(stub_info_name: &str, system_table: &SystemTable<Boot>) -> Result<()> {
     let boot_services = system_table.boot_services();
     let runtime_services = system_table.runtime_services();
 
@@ -243,7 +239,7 @@ pub fn export_efi_variables(system_table: &SystemTable<Boot>) -> Result<()> {
             cstr16!("StubInfo"),
             &BOOT_LOADER_VENDOR_UUID,
             default_attributes,
-            &STUB_INFO_STRING
+            &stub_info_name
                 .encode_utf16()
                 .flat_map(|c| c.to_le_bytes())
                 .collect::<Vec<u8>>(),

rust/linux-bootloader/src/lib.rs

@@ -0,0 +1,12 @@
+#![no_std]
+
+extern crate alloc;
+
+pub mod efivars;
+pub mod linux_loader;
+pub mod measure;
+pub mod pe_loader;
+pub mod pe_section;
+pub mod tpm;
+pub mod uefi_helpers;
+pub mod unified_sections;

rust/linux-bootloader/src/measure.rs

@@ -12,10 +12,7 @@ use crate::{
 
 const TPM_PCR_INDEX_KERNEL_IMAGE: PcrIndex = PcrIndex(11);
 
-pub unsafe fn measure_image(
+pub fn measure_image(system_table: &SystemTable<Boot>, image: PeInMemory) -> uefi::Result<u32> {
-    system_table: &SystemTable<Boot>,
-    image: PeInMemory,
-) -> uefi::Result<u32> {
     let runtime_services = system_table.runtime_services();
     let boot_services = system_table.boot_services();
 

rust/stub/Cargo.lock

@@ -83,10 +83,8 @@ dependencies = [
 name = "lanzaboote_stub"
 version = "0.3.0"
 dependencies = [
- "bitflags",
+ "linux-bootloader",
- "goblin",
  "log",
- "sha1_smol",
  "sha2",
  "uefi",
  "uefi-services",
@@ -98,6 +96,17 @@ version = "0.2.147"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b4668fb0ea861c1df094127ac5f1da3409a82116a4ba74fca2e58ef927159bb3"
 
+[[package]]
+name = "linux-bootloader"
+version = "0.3.0"
+dependencies = [
+ "bitflags",
+ "goblin",
+ "log",
+ "sha1_smol",
+ "uefi",
+]
+
 [[package]]
 name = "log"
 version = "0.4.19"

rust/stub/Cargo.toml

@@ -9,16 +9,12 @@ rust-version = "1.68"
 [dependencies]
 uefi = { version = "0.24.0", default-features = false, features = [ "alloc", "global_allocator" ] }
 uefi-services = { version = "0.21.0", default-features = false, features = [ "panic_handler", "logger" ] }
-goblin = { version = "0.6.1", default-features = false, features = [ "pe64", "alloc" ]}
-bitflags = "2.3.3"
-
 # Even in debug builds, we don't enable the debug logs, because they generate a lot of spam from goblin.
 log = { version = "0.4.19", default-features = false, features = [ "max_level_info", "release_max_level_warn" ]}
-
 # Use software implementation because the UEFI target seems to need it.
 sha2 = { version = "0.10.7", default-features = false, features = ["force-soft"], optional = true }
-# SHA1 for TPM TCG interface version 1.
+# Our linux-bootloader crate containing most of what we need
-sha1_smol = "1.0.0"
+linux-bootloader = { path = "../linux-bootloader" }
 
 [features]
 default = [ "thin" ]

rust/stub/src/common.rs

@@ -1,9 +1,9 @@
 use alloc::vec::Vec;
 use uefi::{prelude::*, CStr16, CString16, Result};
 
-use crate::linux_loader::InitrdLoader;
+use linux_bootloader::linux_loader::InitrdLoader;
-use crate::pe_loader::Image;
+use linux_bootloader::pe_loader::Image;
-use crate::pe_section::pe_section_as_string;
+use linux_bootloader::pe_section::pe_section_as_string;
 
 /// Extract a string, stored as UTF-8, from a PE section.
 pub fn extract_string(pe_data: &[u8], section: &str) -> Result<CString16> {

rust/stub/src/fat.rs

@@ -2,8 +2,8 @@ use alloc::vec::Vec;
 use uefi::{prelude::*, CString16, Result};
 
 use crate::common::{boot_linux_unchecked, extract_string};
-use crate::pe_section::pe_section;
+use linux_bootloader::pe_section::pe_section;
-use crate::uefi_helpers::booted_image_file;
+use linux_bootloader::uefi_helpers::booted_image_file;
 
 /// Extract bytes from a PE section.
 pub fn extract_bytes(pe_data: &[u8], section: &str) -> Result<Vec<u8>> {

rust/stub/src/main.rs

@@ -5,14 +5,6 @@
 extern crate alloc;
 
 mod common;
-mod efivars;
-mod linux_loader;
-mod measure;
-mod pe_loader;
-mod pe_section;
-mod tpm;
-mod uefi_helpers;
-mod unified_sections;
 
 #[cfg(feature = "fat")]
 mod fat;
@@ -23,13 +15,15 @@ mod thin;
 #[cfg(all(feature = "fat", feature = "thin"))]
 compile_error!("A thin and fat stub cannot be produced at the same time, disable either `thin` or `fat` feature");
 
-use efivars::{export_efi_variables, get_loader_features, EfiLoaderFeatures};
+use linux_bootloader::efivars::{export_efi_variables, get_loader_features, EfiLoaderFeatures};
+use linux_bootloader::measure::measure_image;
+use linux_bootloader::tpm::tpm_available;
+use linux_bootloader::uefi_helpers::booted_image_file;
 use log::info;
-use measure::measure_image;
-use tpm::tpm_available;
 use uefi::prelude::*;
 
-use crate::uefi_helpers::booted_image_file;
+/// Lanzaboote stub name
+pub static STUB_NAME: &str = concat!("lanzastub ", env!("CARGO_PKG_VERSION"));
 
 /// Print the startup logo on boot.
 fn print_logo() {
@@ -54,18 +48,16 @@ fn main(handle: Handle, mut system_table: SystemTable<Boot>) -> Status {
 
     if tpm_available(system_table.boot_services()) {
         info!("TPM available, will proceed to measurements.");
-        unsafe {
+        // Iterate over unified sections and measure them
-            // Iterate over unified sections and measure them
+        // For now, ignore failures during measurements.
-            // For now, ignore failures during measurements.
+        // TODO: in the future, devise a threat model where this can fail
-            // TODO: in the future, devise a threat model where this can fail
+        // and ensure this hard-fail correctly.
-            // and ensure this hard-fail correctly.
+        let _ = measure_image(
-            let _ = measure_image(
+            &system_table,
-                &system_table,
+            booted_image_file(system_table.boot_services()).unwrap(),
-                booted_image_file(system_table.boot_services()).unwrap(),
+        );
-            );
+        // TODO: Measure kernel parameters
-            // TODO: Measure kernel parameters
+        // TODO: Measure sysexts
-            // TODO: Measure sysexts
-        }
     }
 
     if let Ok(features) = get_loader_features(system_table.runtime_services()) {
@@ -74,7 +66,7 @@ fn main(handle: Handle, mut system_table: SystemTable<Boot>) -> Status {
             info!("Random seed is available, but lanzaboote does not support it yet.");
         }
     }
-    export_efi_variables(&system_table).expect("Failed to export stub EFI variables");
+    export_efi_variables(STUB_NAME, &system_table).expect("Failed to export stub EFI variables");
 
     let status;
 

rust/stub/src/thin.rs

@@ -4,8 +4,8 @@ use sha2::{Digest, Sha256};
 use uefi::{prelude::*, proto::loaded_image::LoadedImage, CStr16, CString16, Result};
 
 use crate::common::{boot_linux_unchecked, extract_string};
-use crate::pe_section::pe_section;
+use linux_bootloader::pe_section::pe_section;
-use crate::{linux_loader::InitrdLoader, uefi_helpers::booted_image_file};
+use linux_bootloader::{linux_loader::InitrdLoader, uefi_helpers::booted_image_file};
 
 type Hash = sha2::digest::Output<Sha256>;