diff --git a/authfs/fd_server/Android.bp b/authfs/fd_server/Android.bp
index 9c810a8..f82b72f 100644
--- a/authfs/fd_server/Android.bp
+++ b/authfs/fd_server/Android.bp
@@ -13,6 +13,7 @@
         "libclap",
         "liblibc",
         "liblog_rust",
+        "libnix",
     ],
     apex_available: ["com.android.virt"],
 }
diff --git a/authfs/fd_server/src/fsverity.rs b/authfs/fd_server/src/fsverity.rs
new file mode 100644
index 0000000..e89bbd0
--- /dev/null
+++ b/authfs/fd_server/src/fsverity.rs
@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+use nix::ioctl_readwrite;
+use std::io;
+
+// Constants/values from uapi/linux/fsverity.h
+const FS_VERITY_METADATA_TYPE_MERKLE_TREE: u64 = 1;
+const FS_VERITY_METADATA_TYPE_SIGNATURE: u64 = 3;
+const FS_IOCTL_MAGIC: u8 = b'f';
+const FS_IOCTL_READ_VERITY_METADATA: u8 = 135;
+
+#[repr(C)]
+pub struct fsverity_read_metadata_arg {
+    metadata_type: u64,
+    offset: u64,
+    length: u64,
+    buf_ptr: u64,
+    __reserved: u64,
+}
+
+ioctl_readwrite!(
+    read_verity_metadata,
+    FS_IOCTL_MAGIC,
+    FS_IOCTL_READ_VERITY_METADATA,
+    fsverity_read_metadata_arg
+);
+
+fn read_metadata(fd: i32, metadata_type: u64, offset: u64, buf: &mut [u8]) -> io::Result<usize> {
+    let mut arg = fsverity_read_metadata_arg {
+        metadata_type,
+        offset,
+        length: buf.len() as u64,
+        buf_ptr: buf.as_mut_ptr() as u64,
+        __reserved: 0,
+    };
+    Ok(unsafe { read_verity_metadata(fd, &mut arg) }.map_err(|e| {
+        if let nix::Error::Sys(errno) = e {
+            io::Error::from_raw_os_error(errno as i32)
+        } else {
+            // Document of nix::sys::ioctl indicates the macro-generated function always returns an
+            // nix::errno::Errno, which can be converted nix::Error::Sys above. As the result, this
+            // branch is unreachable.
+            unreachable!();
+        }
+    })? as usize)
+}
+
+/// Read the raw Merkle tree from the fd, if it exists. The API semantics is similar to a regular
+/// pread(2), and may not return full requested buffer.
+pub fn read_merkle_tree(fd: i32, offset: u64, buf: &mut [u8]) -> io::Result<usize> {
+    read_metadata(fd, FS_VERITY_METADATA_TYPE_MERKLE_TREE, offset, buf)
+}
+
+/// Read the fs-verity signature from the fd (if exists). The returned signature should be complete.
+pub fn read_signature(fd: i32, buf: &mut [u8]) -> io::Result<usize> {
+    read_metadata(fd, FS_VERITY_METADATA_TYPE_SIGNATURE, 0 /* offset */, buf)
+}
diff --git a/authfs/fd_server/src/main.rs b/authfs/fd_server/src/main.rs
index 44817d5..99b6e9e 100644
--- a/authfs/fd_server/src/main.rs
+++ b/authfs/fd_server/src/main.rs
@@ -25,6 +25,8 @@
 //! [1] Since the remote binder is not ready, this currently implementation uses local binder
 //!     first.
 
+mod fsverity;
+
 use std::cmp::min;
 use std::collections::BTreeMap;
 use std::convert::TryInto;
@@ -32,7 +34,7 @@
 use std::fs::File;
 use std::io;
 use std::os::unix::fs::FileExt;
-use std::os::unix::io::FromRawFd;
+use std::os::unix::io::{AsRawFd, FromRawFd};
 
 use anyhow::{bail, Context, Result};
 use binder::IBinderInternal; // TODO(178852354): remove once set_requesting_sid is exposed in the API.
@@ -130,18 +132,22 @@
         let offset: u64 = validate_and_cast_offset(offset)?;
 
         match &self.get_file_config(id)? {
-            FdConfig::Readonly { alt_merkle_tree, .. } => {
-                if let Some(file) = &alt_merkle_tree {
-                    read_into_buf(&file, size, offset).map_err(|e| {
+            FdConfig::Readonly { file, alt_merkle_tree, .. } => {
+                if let Some(tree_file) = &alt_merkle_tree {
+                    read_into_buf(&tree_file, size, offset).map_err(|e| {
                         error!("readFsverityMerkleTree: read error: {}", e);
                         Status::from(ERROR_IO)
                     })
                 } else {
-                    // TODO(victorhsieh) retrieve from the fd when the new ioctl is ready
-                    Err(new_binder_exception(
-                        ExceptionCode::UNSUPPORTED_OPERATION,
-                        "Not implemented yet",
-                    ))
+                    let mut buf = vec![0; size];
+                    let s = fsverity::read_merkle_tree(file.as_raw_fd(), offset, &mut buf)
+                        .map_err(|e| {
+                            error!("readFsverityMerkleTree: failed to retrieve merkle tree: {}", e);
+                            Status::from(e.raw_os_error().unwrap_or(ERROR_IO))
+                        })?;
+                    debug_assert!(s <= buf.len(), "Shouldn't return more bytes than asked");
+                    buf.truncate(s);
+                    Ok(buf)
                 }
             }
             FdConfig::ReadWrite(_file) => {
@@ -155,20 +161,24 @@
 
     fn readFsveritySignature(&self, id: i32) -> BinderResult<Vec<u8>> {
         match &self.get_file_config(id)? {
-            FdConfig::Readonly { alt_signature, .. } => {
-                if let Some(file) = &alt_signature {
+            FdConfig::Readonly { file, alt_signature, .. } => {
+                if let Some(sig_file) = &alt_signature {
                     // Supposedly big enough buffer size to store signature.
                     let size = MAX_REQUESTING_DATA as usize;
-                    read_into_buf(&file, size, 0).map_err(|e| {
+                    let offset = 0;
+                    read_into_buf(&sig_file, size, offset).map_err(|e| {
                         error!("readFsveritySignature: read error: {}", e);
                         Status::from(ERROR_IO)
                     })
                 } else {
-                    // TODO(victorhsieh) retrieve from the fd when the new ioctl is ready
-                    Err(new_binder_exception(
-                        ExceptionCode::UNSUPPORTED_OPERATION,
-                        "Not implemented yet",
-                    ))
+                    let mut buf = vec![0; MAX_REQUESTING_DATA as usize];
+                    let s = fsverity::read_signature(file.as_raw_fd(), &mut buf).map_err(|e| {
+                        error!("readFsverityMerkleTree: failed to retrieve merkle tree: {}", e);
+                        Status::from(e.raw_os_error().unwrap_or(ERROR_IO))
+                    })?;
+                    debug_assert!(s <= buf.len(), "Shouldn't return more bytes than asked");
+                    buf.truncate(s);
+                    Ok(buf)
                 }
             }
             FdConfig::ReadWrite(_file) => {