pa-fazil
/
android_packages_modules_Virtualization
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

authfs: return Merkle tree hidden in the filesystem 

fd_server is capable to return a tree "dump" from a file. But for the
normal case where the served file already has fs-verity, we should use
the new AuthFsTestCases ioctl to retrieve the tree and signature.

Test is not included due to some setup difficulty (passed locally).

Bug: 171280402
Test: atest AuthFsTestCases

Change-Id: Ieba685ad065b69edafadce462d112b8fd118686a
This commit is contained in:
Victor Hsieh 2021-03-15 11:01:23 -07:00
parent a9a9a626ce
commit 4dc85c9ebc
3 changed files with 99 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
authfs/fd_server/Android.bp
View File

@ -13,6 +13,7 @@ rust_binary {
"libclap",
"liblibc",
"liblog_rust",
"libnix",
],
apex_available: ["com.android.virt"],
}

71
authfs/fd_server/src/fsverity.rs Normal file
View File

@ -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)
}

44
authfs/fd_server/src/main.rs
View File

@ -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::ffi::CString;
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 @@ impl IVirtFdService for FdService {
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 @@ impl IVirtFdService for FdService {
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) => {