Switch to goblin::elf

Cargo.lock

@@ -20,27 +20,38 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
-[[package]]
-name = "elf"
-version = "0.7.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4445909572dbd556c457c849c4ca58623d84b27c8fff1e74b0b4227d8b90d17b"
-
 [[package]]
 name = "freeloader"
 version = "0.1.0"
 dependencies = [
- "elf",
+ "goblin",
  "log",
  "uefi",
 ]
 
+[[package]]
+name = "goblin"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b363a30c165f666402fe6a3024d3bec7ebc898f96a4a23bd1c99f8dbf3f4f47"
+dependencies = [
+ "log",
+ "plain",
+ "scroll",
+]
+
 [[package]]
 name = "log"
 version = "0.4.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a7a70ba024b9dc04c27ea2f0c0548feb474ec5c54bba33a7f72f873a39d07b24"
 
+[[package]]
+name = "plain"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4596b6d070b27117e987119b4dac604f3c58cfb0b191112e24771b2faeac1a6"
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.86"
@@ -79,6 +90,26 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "scroll"
+version = "0.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6ab8598aa408498679922eff7fa985c25d58a90771bd6be794434c5277eab1a6"
+dependencies = [
+ "scroll_derive",
+]
+
+[[package]]
+name = "scroll_derive"
+version = "0.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f81c2fde025af7e69b1d1420531c8a8811ca898919db177141a85313b1cb932"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.72",
+]
+
 [[package]]
 name = "syn"
 version = "1.0.109"

Cargo.toml

@@ -6,4 +6,4 @@ edition = "2021"
 [dependencies]
 uefi = { version = "0.29.0", default-features = false, features = [ "alloc", "global_allocator", "panic_handler", "logger" ] }
 log = { version = "0.4.22", default-features = false }
-elf = { version = "0.7.4", default_features = false }
+goblin = { version = "0.8.2", default-features = false, features = [ "elf64", "elf32", "endian_fd" ] }

notes.md

@@ -40,3 +40,172 @@ Tons of arch-specific restrictions
 * Pointers are passed as 32-bit, must be within the first 4G
 * First 4G of virtual memory must be identity mapped
 * Kernel virtual address must also be mapped to kernel (normally `0xffff_ffff_8000_0000`)
+
+## Sample kernel
+modinfo:
+```
+0xffffffff8282b000:
+	type:	(0x01) MODINFO_NAME
+	len:	20
+	value:	/boot/kernel/kernel
+ 0xffffffff8282b020:
+	type:	(0x02) MODINFO_TYPE
+	len:	11
+	value:	elf kernel
+ 0xffffffff8282b038:
+	type:	(0x03) MODINFO_ADDR
+	len:	8
+	value:	0xffffffff80200000
+ 0xffffffff8282b048:
+	type:	(0x04) MODINFO_SIZE
+	len:	8
+	value:	32731368
+ 0xffffffff8282b058:
+	type:	(0x9004) MODINFO_METADATA | MODINFOMD_EFI_MAP
+	len:	6080
+	value:	buffer contents omitted
+ 0xffffffff8282c820:
+	type:	(0x9005) MODINFO_METADATA | MODINFOMD_EFI_FB
+	len:	48
+	value:	0x0000000084000000
+ 0xffffffff8282c858:
+	type:	(0x800d) MODINFO_METADATA | MODINFOMD_KEYBUF
+	len:	33028
+	value:	buffer contents omitted
+ 0xffffffff82834968:
+	type:	(0x800c) MODINFO_METADATA | MODINFOMD_FW_HANDLE
+	len:	8
+	value:	buffer contents omitted
+ 0xffffffff82834978:
+	type:	(0x9006) MODINFO_METADATA | MODINFOMD_MODULEP
+	len:	8
+	value:	
+ 0xffffffff82834988:
+	type:	(0x8008) MODINFO_METADATA | MODINFOMD_KERNEND
+	len:	8
+	value:	0x0000000002837000
+ 0xffffffff82834998:
+	type:	(0x8006) MODINFO_METADATA | MODINFOMD_ENVP
+	len:	8
+	value:	0x000000000282a000
+ 0xffffffff828349a8:
+	type:	(0x8007) MODINFO_METADATA | MODINFOMD_HOWTO
+	len:	4
+	value:	0x20000000
+ 0xffffffff828349b8:
+	type:	(0x8002) MODINFO_METADATA | MODINFOMD_ELFHDR
+	len:	64
+	value:	buffer contents omitted
+ 0xffffffff82834a00:
+	type:	(0x8005) MODINFO_METADATA | MODINFOMD_DYNAMIC
+	len:	8
+	value:	0xffffffff81600000
+ 0xffffffff82834a10:
+	type:	(0x8004) MODINFO_METADATA | MODINFOMD_ESYM
+	len:	8
+	value:	0xffffffff821370e8
+ 0xffffffff82834a20:
+	type:	(0x8003) MODINFO_METADATA | MODINFOMD_SSYM
+	len:	8
+	value:	0xffffffff81e00000
+ 0xffffffff82834a30:
+	type:	(0x8009) MODINFO_METADATA | MODINFOMD_SHDR
+	len:	3904
+	value:	buffer contents omitted
+ 0xffffffff82835978:
+	type:	(0x01) MODINFO_NAME
+	len:	20
+	value:	/boot/kernel/zfs.ko
+ 0xffffffff82835998:
+	type:	(0x02) MODINFO_TYPE
+	len:	15
+	value:	elf obj module
+ 0xffffffff828359b0:
+	type:	(0x03) MODINFO_ADDR
+	len:	8
+	value:	0xffffffff82138000
+ 0xffffffff828359c0:
+	type:	(0x04) MODINFO_SIZE
+	len:	8
+	value:	6084104
+ 0xffffffff828359d0:
+	type:	(0x8002) MODINFO_METADATA | MODINFOMD_ELFHDR
+	len:	64
+	value:	buffer contents omitted
+ 0xffffffff82835a18:
+	type:	(0x8009) MODINFO_METADATA | MODINFOMD_SHDR
+	len:	1984
+	value:	buffer contents omitted
+ 0xffffffff828361e0:
+	type:	(0x01) MODINFO_NAME
+	len:	26
+	value:	/boot/kernel/cryptodev.ko
+ 0xffffffff82836208:
+	type:	(0x02) MODINFO_TYPE
+	len:	15
+	value:	elf obj module
+ 0xffffffff82836220:
+	type:	(0x03) MODINFO_ADDR
+	len:	8
+	value:	0xffffffff82706000
+ 0xffffffff82836230:
+	type:	(0x04) MODINFO_SIZE
+	len:	8
+	value:	30680
+ 0xffffffff82836240:
+	type:	(0x8002) MODINFO_METADATA | MODINFOMD_ELFHDR
+	len:	64
+	value:	buffer contents omitted
+ 0xffffffff82836288:
+	type:	(0x8009) MODINFO_METADATA | MODINFOMD_SHDR
+	len:	1856
+	value:	buffer contents omitted
+ 0xffffffff828369d0:
+	type:	(0x01) MODINFO_NAME
+	len:	12
+	value:	/etc/hostid
+ 0xffffffff828369e8:
+	type:	(0x02) MODINFO_TYPE
+	len:	9
+	value:	hostuuid
+ 0xffffffff82836a00:
+	type:	(0x03) MODINFO_ADDR
+	len:	8
+	value:	0xffffffff8270d7d8
+ 0xffffffff82836a10:
+	type:	(0x04) MODINFO_SIZE
+	len:	8
+	value:	37
+ 0xffffffff82836a20:
+	type:	(0x01) MODINFO_NAME
+	len:	14
+	value:	/boot/entropy
+ 0xffffffff82836a38:
+	type:	(0x02) MODINFO_TYPE
+	len:	19
+	value:	boot_entropy_cache
+ 0xffffffff82836a58:
+	type:	(0x03) MODINFO_ADDR
+	len:	8
+	value:	0xffffffff8270d7fd
+ 0xffffffff82836a68:
+	type:	(0x04) MODINFO_SIZE
+	len:	8
+	value:	4096
+ 0xffffffff82836a78:
+	type:	(0x01) MODINFO_NAME
+	len:	6
+	value:	TSLOG
+ 0xffffffff82836a88:
+	type:	(0x02) MODINFO_TYPE
+	len:	11
+	value:	TSLOG data
+ 0xffffffff82836aa0:
+	type:	(0x03) MODINFO_ADDR
+	len:	8
+	value:	0xffffffff8270e7fd
+ 0xffffffff82836ab0:
+	type:	(0x04) MODINFO_SIZE
+	len:	8
+	value:	1159497
+```

src/abi.rs

@@ -181,8 +181,8 @@ impl Serialize for ModuleInfoValue {
 /// TODO: figure out how to make this properly typesafe
 #[derive(Debug, Clone)]
 pub struct ModuleInfoItem {
-    tag: ModuleInfoType,
-    value: ModuleInfoValue,
+    pub tag: ModuleInfoType,
+    pub value: ModuleInfoValue,
 }
 
 impl Serialize for ModuleInfoItem {

src/main.rs

@@ -2,10 +2,11 @@
 #![no_std]
 
 mod abi;
+mod object;
 mod staging;
 
-use elf::endian::NativeEndian;
 use log::info;
+use object::{Kernel, Module};
 use uefi::{fs::FileSystem, prelude::*};
 
 #[entry]
@@ -14,8 +15,6 @@ fn main(image_handle: Handle, mut system_table: SystemTable<Boot>) -> Status {
 
     info!("Starting freeloader");
 
-    let staging_buf = staging::allocate_staging(system_table.boot_services());
-
     let mut esp = FileSystem::new(
         system_table
             .boot_services()
@@ -23,18 +22,18 @@ fn main(image_handle: Handle, mut system_table: SystemTable<Boot>) -> Status {
             .expect("Failed to get ESP handle"),
     );
 
-    let kernel = esp
+    let kernel_data = esp
         .read(cstr16!("efi\\freebsd\\kernel"))
         .expect("Failed to read kernel");
 
-    info!("Loaded kernel");
+    info!("Read kernel");
 
-    staging_buf[..kernel.len()].copy_from_slice(&kernel);
+    let kernel = Kernel::from_elf_bytes(&kernel_data);
 
-    let header =
-        elf::ElfBytes::<NativeEndian>::minimal_parse(staging_buf).expect("Failed to parse kernel");
-
-    info!("Kernel is {:?}", header.ehdr.class);
+    info!(
+        "Kernel metadata is {:#?}",
+        kernel.metadata(core::ptr::null::<u8>())
+    );
 
     loop {
         system_table.boot_services().stall(10_000_000);

src/object.rs

@@ -0,0 +1,75 @@
+extern crate alloc;
+
+use crate::abi::{ModuleInfoItem, ModuleInfoType, ModuleInfoValue, Serialize};
+use alloc::vec::Vec;
+use goblin::elf::Elf;
+use log::info;
+
+#[cfg(target_arch = "x86_64")]
+const NATIVE_ELF_MACHINE: u16 = goblin::elf::header::EM_X86_64;
+
+pub trait Module {
+    /// Associated metadata for this module, including name and type
+    fn metadata(&self, load_address: *const u8) -> Vec<ModuleInfoItem>;
+}
+
+pub struct Kernel<'a> {
+    /// Full ELF
+    elf: &'a [u8],
+    /// Parsed ELF
+    parsed: Elf<'a>,
+    /// Raw ELF header bytes
+    elf_header: &'a [u8],
+}
+
+impl<'a> Kernel<'a> {
+    pub fn from_elf_bytes(elf: &'a [u8]) -> Self {
+        let parsed = Elf::parse(elf).expect("Failed to parse kernel");
+        if parsed.header.e_machine != NATIVE_ELF_MACHINE {
+            panic!("Kernel has wrong ELF machine");
+        }
+
+        let header_size = if parsed.is_64 { 0x40 } else { 0x34 };
+        let elf_header = &elf[..header_size];
+
+        Self {
+            elf,
+            parsed,
+            elf_header,
+        }
+    }
+}
+
+impl<'a> Serialize for Kernel<'a> {
+    fn alignment() -> usize {
+        // On some platforms we need to be aligned to a level 2 page
+        2 * 1024 * 1024
+    }
+
+    fn size(&self) -> usize {
+        todo!()
+    }
+
+    fn serialize(&self, out: &mut [u8]) {
+        todo!()
+    }
+}
+
+impl<'a> Module for Kernel<'a> {
+    fn metadata(&self, load_address: *const u8) -> Vec<ModuleInfoItem> {
+        alloc::vec![
+            ModuleInfoItem {
+                tag: ModuleInfoType::Name,
+                value: ModuleInfoValue::StaticString("/boot/kernel/kernel")
+            },
+            ModuleInfoItem {
+                tag: ModuleInfoType::Type,
+                value: ModuleInfoValue::StaticString("elf kernel")
+            },
+            ModuleInfoItem {
+                tag: ModuleInfoType::ElfHeader,
+                value: ModuleInfoValue::Buffer(self.elf_header.to_vec())
+            },
+        ]
+    }
+}