diff --git a/Cargo.lock b/Cargo.lock
index e12886a..6598979 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,4 +1,179 @@
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 name = "linux_tests"
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diff --git a/Cargo.toml b/Cargo.toml
index 003dfd4..d401652 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,4 +11,11 @@
 license = "BSD-3-Clause"
 edition = "2018"
 
-[dependencies]
\ No newline at end of file
+[dependencies]
+structopt = { path = "rust-crates/rustc_deps/vendor/structopt" }
+libc = { path = "rust-crates/rustc_deps/vendor/libc" }
+
+[patch.crates-io]
+winapi = { path = "rust-crates/rustc_deps/tiny_mirrors/winapi" }
+winapi-build = { path = "rust-crates/rustc_deps/tiny_mirrors/winapi-build" }
+winapi-util = { path = "rust-crates/rustc_deps/tiny_mirrors/winapi-util" }
diff --git a/build.sh b/build.sh
index 87e4eae..3557af4 100755
--- a/build.sh
+++ b/build.sh
@@ -37,6 +37,7 @@
 
 mkdir -p ${OUT_DIR}
 cp target/${TARGET}/debug/virtio_rng_test_util ${OUT_DIR}
+cp target/${TARGET}/debug/virtio_block_test_util ${OUT_DIR}
 
 declare -r BLOCK_SIZE=4096
 declare -r ADDITIONAL_BLOCKS=1024
diff --git a/src/bin/virtio_block_test_util.rs b/src/bin/virtio_block_test_util.rs
new file mode 100644
index 0000000..59d6964
--- /dev/null
+++ b/src/bin/virtio_block_test_util.rs
@@ -0,0 +1,138 @@
+// Copyright 2018 The Fuchsia Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+#![deny(warnings)]
+
+use libc::{self, c_int};
+use std::fs::{self, File, OpenOptions};
+use std::io::{Error, ErrorKind, Read, Seek, SeekFrom, Write};
+use std::os::unix::io::AsRawFd;
+use std::path::Path;
+use structopt::StructOpt;
+
+const DEV_DIR: &str = "/dev";
+
+// Ioctl requests are comprised of 32 bits:
+// [31:30]  Access mode
+// [29:16]  Size of the parameter structure
+// [15:8]   Request type
+// [7:0]    Request number
+// For the ioctls we care about here there are no parameters, so we set only a type and a number.
+// See Linux:include/uapi/asm-generic/ioctl.h for more details.
+const TYPE_SHIFT: usize = 8;
+macro_rules! define_ioctl {
+    ($name:ident, $typ:expr, $num:expr, $return_type:ty) => {
+        fn $name(file: &File) -> $return_type {
+            let request: c_int = ($typ << TYPE_SHIFT) | ($num & 0xff);
+            let mut r: $return_type = 0;
+            unsafe {
+                libc::ioctl(file.as_raw_fd(), request, &mut r);
+            }
+            r
+        }
+    };
+}
+
+// Block ioctl types and number are defined in Linux:include/uapi/linux/fs.h.
+define_ioctl!(block_dev_size, 0x12, 96, u64);
+define_ioctl!(block_dev_sector_size, 0x12, 104, u32);
+
+#[derive(StructOpt, Debug)]
+struct Config {
+    block_size: u32,
+    block_count: u64,
+    #[structopt(subcommand)]
+    cmd: Command,
+}
+
+#[derive(StructOpt, Debug)]
+enum Command {
+    #[structopt(name = "check")]
+    Check,
+    #[structopt(name = "read")]
+    Read { offset: u64, expected: u8 },
+    #[structopt(name = "write")]
+    Write { offset: u64, value: u8 },
+}
+
+fn find_block_device(block_size: u32, block_count: u64, write: bool) -> std::io::Result<File> {
+    let dir = Path::new(DEV_DIR);
+    if !dir.is_dir() {
+        return Err(Error::new(
+            ErrorKind::Other,
+            format!("{} is not a directory", DEV_DIR),
+        ));
+    }
+    for entry in fs::read_dir(dir)?.collect::<std::io::Result<Vec<_>>>()? {
+        if !entry
+            .file_name()
+            .to_str()
+            .map_or(false, |f| f.starts_with("vd"))
+        {
+            continue;
+        }
+        let file = OpenOptions::new()
+            .read(true)
+            .write(write)
+            .open(entry.path())?;
+        if block_size != block_dev_sector_size(&file) {
+            continue;
+        }
+        if block_count != block_dev_size(&file) {
+            continue;
+        }
+        return Ok(file);
+    }
+    Err(Error::new(ErrorKind::NotFound, "Block device not found"))
+}
+
+fn read_block(
+    block_dev: &mut File,
+    block_size: u32,
+    offset: u64,
+    expected: u8,
+) -> std::io::Result<()> {
+    block_dev.seek(SeekFrom::Start(offset * block_size as u64))?;
+    let mut data: Vec<u8> = vec![0; block_size as usize];
+    block_dev.read_exact(&mut data)?;
+    if !data.iter().all(|&b| b == expected) {
+        return Err(Error::new(ErrorKind::Other, "Incorrect data read"));
+    }
+    Ok(())
+}
+
+fn write_block(
+    block_dev: &mut File,
+    block_size: u32,
+    offset: u64,
+    value: u8,
+) -> std::io::Result<()> {
+    block_dev.seek(SeekFrom::Start(offset * block_size as u64))?;
+    let data: Vec<u8> = vec![value; block_size as usize];
+    block_dev.write_all(&data)?;
+    block_dev.sync_all()?;
+    Ok(())
+}
+
+fn main() -> std::io::Result<()> {
+    let config = Config::from_args();
+    let write = if let Command::Write { .. } = config.cmd {
+        true
+    } else {
+        false
+    };
+    let mut block_dev = find_block_device(config.block_size, config.block_count, write)?;
+    let result = match config.cmd {
+        Command::Check => Ok(()),
+        Command::Read { offset, expected } => {
+            read_block(&mut block_dev, config.block_size, offset, expected)
+        }
+        Command::Write { offset, value } => {
+            write_block(&mut block_dev, config.block_size, offset, value)
+        }
+    };
+    if result.is_ok() {
+        println!("PASS");
+    }
+    result
+}