Add support for caculating kernel eventlog digist when using OVMF+QEMU

Fix: #633

Signed-off-by: OuyangHang33 <[email protected]>

Author: OuyangHang33

td-shim-tools/src/bin/td-payload-reference-calculator/README.md

@@ -13,7 +13,7 @@ wget https://github.com/Xynnn007/td-payload-reference-provider/raw/main/tests/bz
 
 Test with the example bzImage
 ```
-cargo run -- kernel -k bzImage -s 0x10000000
+cargo run -p td-shim-tools --bin td-payload-reference-calculator -- kernel -k bzImage -s 0x10000000
 ```
 
 The `kernel-size` parameter here means `KERNEL_SIZE` defined in guest firmware, s.t. [TD-SHIM](https://github.com/confidential-containers/td-shim)
@@ -25,11 +25,23 @@ Will get the result
 
 which is from https://github.com/confidential-containers/attestation-service/pull/33/files#diff-1a4e5ad4c3b043c019c00bc3b3072fd6e1e5b03a5ce8c498e1c0acaf697d9d3fR265
 
+When using TDVF + QEMU Kernel Direct Boot, the kernel eventlog digest will be pre-processed by QEMU Kernel Direct Boot logic. Which is from https://github.com/confidential-containers/td-shim/issues/633
+
+Test with the example bzImage
+```
+cargo run -p td-shim-tools --bin td-payload-reference-calculator -- kernel -k bzImage -q
+```
+
+Will get the result
+```
+a5e921ae5bde7ab989216da059057741688eae9114b854ce60733824f93ade8a848f19c719f3fdd5c4f0d7178164a5e2
+```
+
 ### Kernel Parameter
 
 Test
 ```
-cargo run -- param -p "root=/dev/vda1 console=hvc0 rw" -s 0x1000
+cargo run  -p td-shim-tools --bin td-payload-reference-calculator -- param -p "root=/dev/vda1 console=hvc0 rw" -s 0x1000
 ```
 
 Will get the result

td-shim-tools/src/bin/td-payload-reference-calculator/main.rs

@@ -14,6 +14,18 @@ use std::{convert::TryFrom, path::Path};
 pub const KERNEL_SIZE: &str = "0x2000000";
 pub const KERNEL_PARAM_SIZE: &str = "0x1000";
 
+// Refer to https://learn.microsoft.com/en-us/windows/win32/debug/pe-format#signature-image-only,
+// file offset specified at offset 0x3c,
+// size of PE signature is 4: "PE\0\0"
+const IMAGE_PE_OFFSET: usize = 0x003c;
+const PE_SIGNATURE_SIZE: u32 = 4;
+const IMGAE_BEGIN_CHECKSUM_ADDR: usize = 0x0000;
+const IMGAE_BEGIN_CHECKSUM_SIZE: usize = 0x00da;
+const IMGAE_CERT_TABLE_ADDR: usize = 0x00de;
+const IMGAE_CERT_TABLE_SIZE: usize = 0x004c;
+const IMGAE_HEADERS_ADDR: usize = 0x0132;
+const IMGAE_HEADERS_SIZE: usize = 0x00ce;
+
 fn kernel(path: &str, size: &str) -> Result<String> {
     let path = Path::new(path).to_path_buf();
     let siz = parse::<u64>(size)?;
@@ -31,6 +43,92 @@ fn param(param: &str, size: &str) -> Result<String> {
     padding_digest(param, siz)
 }
 
+fn qemu(path: &str, size: &str) -> Result<String> {
+    let path = Path::new(path).to_path_buf();
+    let siz = parse::<u64>(size)?;
+    let file_size = std::fs::metadata(&path)?.len();
+    if file_size > siz {
+        bail!("File size should be less than `kernel-size`");
+    }
+    let buf = std::fs::read(path)?;
+    qemu_patch(buf)
+}
+
+fn qemu_patch(mut buf: Vec<u8>) -> Result<String> {
+    // patching type_of_loader @0x210
+    buf[0x210] = 0xb0;
+
+    // patching loadflags @0x211
+    buf[0x211] = 0x81;
+
+    //patching heap_end_ptr @0x224 cmdline_addr - real_addr - 0x200 = 0xfe00
+    buf[0x224] = 0x00;
+    buf[0x225] = 0xfe;
+
+    //patching cmd_line_ptr @0x228 cmdline_addr = 0x20000
+    buf[0x228] = 0x00;
+    buf[0x229] = 0x00;
+    buf[0x22A] = 0x02;
+
+    let mut hasher = sha2::Sha384::new();
+    let image = buf.clone();
+    let (number_of_region_entry, regions_base, regions_size) = get_image_regions(image);
+
+    for index in 0..number_of_region_entry {
+        hasher.update(&buf[regions_base[index]..regions_base[index] + regions_size[index]]);
+    }
+
+    let res = hasher.finalize();
+    Ok(hex::encode(res))
+}
+
+fn get_image_regions(buf: Vec<u8>) -> (usize, Vec<usize>, Vec<usize>) {
+    // These 3 regions are known.
+    let mut number_of_region_entry = 3;
+    let mut regions_base = vec![
+        IMGAE_BEGIN_CHECKSUM_ADDR,
+        IMGAE_CERT_TABLE_ADDR,
+        IMGAE_HEADERS_ADDR,
+    ];
+    let mut regions_size = vec![
+        IMGAE_BEGIN_CHECKSUM_SIZE,
+        IMGAE_CERT_TABLE_SIZE,
+        IMGAE_HEADERS_SIZE,
+    ];
+
+    // Refer to https://learn.microsoft.com/en-us/windows/win32/debug/pe-format#coff-file-header-object-and-image,
+    // After the signature of an image file is COFF File Header
+    // the NumberOfSections' offset is 2
+    let coff_file_header_offset = ((buf[IMAGE_PE_OFFSET + 3] as u32) << 24)
+        | ((buf[IMAGE_PE_OFFSET + 2] as u32) << 16)
+        | ((buf[IMAGE_PE_OFFSET + 1] as u32) << 8)
+        | (buf[IMAGE_PE_OFFSET] as u32) + PE_SIGNATURE_SIZE;
+    let number_of_pecoff_entry = buf[coff_file_header_offset as usize + 2];
+    number_of_region_entry += number_of_pecoff_entry as usize;
+
+    // Refer to https://learn.microsoft.com/en-us/windows/win32/debug/pe-format#section-table-section-headers
+    // SizeOfRawData       Offset: 16      Size:4
+    // PointerToRawData    Offset: 20      Size:4
+    // SizeOfSection                       Size:40
+    let mut p = IMGAE_HEADERS_ADDR + 8;
+    for _i in 0..number_of_pecoff_entry {
+        p += 16;
+        let size = ((buf[p + 3] as u32) << 24)
+            | ((buf[p + 2] as u32) << 16)
+            | ((buf[p + 1] as u32) << 8)
+            | buf[p] as u32;
+        p += 4;
+        let base = ((buf[p + 3] as u32) << 24)
+            | ((buf[p + 2] as u32) << 16)
+            | ((buf[p + 1] as u32) << 8)
+            | buf[p] as u32;
+        regions_base.push(base as usize);
+        regions_size.push(size as usize);
+        p += 20;
+    }
+    (number_of_region_entry, regions_base, regions_size)
+}
+
 fn padding_digest(mut buf: Vec<u8>, len: usize) -> Result<String> {
     let diff = len - buf.len();
 
@@ -56,7 +154,8 @@ fn main() {
                         .required(false)
                         .default_value(KERNEL_SIZE)
                         .action(ArgAction::Set),
-                ),
+                )
+                .arg(arg!(-q --"qemu" "QEMU Kernel Direct Boot patch string").required(false)),
         )
         .subcommand(
             command!("param")
@@ -78,7 +177,12 @@ fn main() {
         Some(("kernel", args)) => {
             let path = args.get_one::<String>("kernel").unwrap();
             let siz = args.get_one::<String>("size").unwrap();
-            kernel(path, siz)
+            // let qflag = args.get_one::<String>("qemu").unwrap();
+            if args.get_flag("qemu") {
+                qemu(path, siz)
+            } else {
+                kernel(path, siz)
+            }
         }
         Some(("param", args)) => {
             let parameter = args.get_one::<String>("parameter").unwrap();