compsvc_worker: refactor authfs into another module
This should pave the way to make several upcoming work easier.
Bug: 194267113
Test: odrefresh generates correct output
Change-Id: I271d7b7f99a5d5eb7408152112884492354a94c2
diff --git a/compos/Android.bp b/compos/Android.bp
index 9428210..1854291 100644
--- a/compos/Android.bp
+++ b/compos/Android.bp
@@ -58,7 +58,6 @@
"liblog_rust",
"libminijail_rust",
"libnix",
- "libscopeguard",
],
prefer_rlib: true,
apex_available: [
diff --git a/compos/src/authfs.rs b/compos/src/authfs.rs
new file mode 100644
index 0000000..ce9aaf8
--- /dev/null
+++ b/compos/src/authfs.rs
@@ -0,0 +1,144 @@
+/*
+ * 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 anyhow::{bail, Context, Result};
+use log::warn;
+use minijail::Minijail;
+use nix::sys::statfs::{statfs, FsType};
+use std::fs::{File, OpenOptions};
+use std::path::Path;
+use std::thread::sleep;
+use std::time::{Duration, Instant};
+
+const AUTHFS_BIN: &str = "/system/bin/authfs";
+const AUTHFS_SETUP_POLL_INTERVAL_MS: Duration = Duration::from_millis(50);
+const AUTHFS_SETUP_TIMEOUT_SEC: Duration = Duration::from_secs(10);
+const FUSE_SUPER_MAGIC: FsType = FsType(0x65735546);
+
+/// The number that hints the future file descriptor. These are not really file descriptor, but
+/// represents the file descriptor number to pass to the task.
+pub type PseudoRawFd = i32;
+
+/// Annotation of input file descriptor.
+#[derive(Debug)]
+pub struct InFdAnnotation {
+ /// A number/file descriptor that is supposed to represent a remote file.
+ pub fd: PseudoRawFd,
+
+ /// The file size of the remote file. Remote input files are supposed to be immutable and
+ /// to be verified with fs-verity by authfs.
+ pub file_size: u64,
+}
+
+/// Annotation of output file descriptor.
+#[derive(Debug)]
+pub struct OutFdAnnotation {
+ /// A number/file descriptor that is supposed to represent a remote file.
+ pub fd: PseudoRawFd,
+}
+
+/// An `AuthFs` instance is supposed to be backed by the `authfs` process. When the lifetime of the
+/// instance is over, the process is terminated and the FUSE is unmounted.
+pub struct AuthFs {
+ mountpoint: String,
+ jail: Minijail,
+}
+
+impl AuthFs {
+ /// Mount an authfs at `mountpoint` with specified FD annotations.
+ pub fn mount_and_wait(
+ mountpoint: &str,
+ in_fds: &[InFdAnnotation],
+ out_fds: &[OutFdAnnotation],
+ debuggable: bool,
+ ) -> Result<AuthFs> {
+ let jail = jail_authfs(mountpoint, in_fds, out_fds, debuggable)?;
+ wait_until_authfs_ready(mountpoint)?;
+ Ok(AuthFs { mountpoint: mountpoint.to_string(), jail })
+ }
+
+ /// Open a file at authfs' root directory.
+ pub fn open_file(&self, basename: PseudoRawFd, writable: bool) -> Result<File> {
+ OpenOptions::new()
+ .read(true)
+ .write(writable)
+ .open(format!("{}/{}", self.mountpoint, basename))
+ .with_context(|| format!("open authfs file {}", basename))
+ }
+}
+
+impl Drop for AuthFs {
+ fn drop(&mut self) {
+ if let Err(e) = self.jail.kill() {
+ if !matches!(e, minijail::Error::Killed(_)) {
+ warn!("Failed to kill authfs: {}", e);
+ }
+ }
+ }
+}
+
+fn jail_authfs(
+ mountpoint: &str,
+ in_fds: &[InFdAnnotation],
+ out_fds: &[OutFdAnnotation],
+ debuggable: bool,
+) -> Result<Minijail> {
+ // TODO(b/185175567): Run in a more restricted sandbox.
+ let jail = Minijail::new()?;
+
+ let mut args = vec![
+ AUTHFS_BIN.to_string(),
+ mountpoint.to_string(),
+ "--cid=2".to_string(), // Always use host unless we need to support other cases
+ ];
+ for conf in in_fds {
+ // TODO(b/185178698): Many input files need to be signed and verified.
+ // or can we use debug cert for now, which is better than nothing?
+ args.push("--remote-ro-file-unverified".to_string());
+ args.push(format!("{}:{}:{}", conf.fd, conf.fd, conf.file_size));
+ }
+ for conf in out_fds {
+ args.push("--remote-new-rw-file".to_string());
+ args.push(format!("{}:{}", conf.fd, conf.fd));
+ }
+
+ let preserve_fds = if debuggable {
+ vec![1, 2] // inherit/redirect stdout/stderr for debugging
+ } else {
+ vec![]
+ };
+
+ let _pid = jail.run(Path::new(AUTHFS_BIN), &preserve_fds, &args)?;
+ Ok(jail)
+}
+
+fn wait_until_authfs_ready(mountpoint: &str) -> Result<()> {
+ let start_time = Instant::now();
+ loop {
+ if is_fuse(mountpoint)? {
+ break;
+ }
+ if start_time.elapsed() > AUTHFS_SETUP_TIMEOUT_SEC {
+ bail!("Time out mounting authfs");
+ }
+ sleep(AUTHFS_SETUP_POLL_INTERVAL_MS);
+ }
+ Ok(())
+}
+
+fn is_fuse(path: &str) -> Result<bool> {
+ Ok(statfs(path)?.filesystem_type() == FUSE_SUPER_MAGIC)
+}
diff --git a/compos/src/compsvc_worker.rs b/compos/src/compsvc_worker.rs
index 0456d58..f33659e 100644
--- a/compos/src/compsvc_worker.rs
+++ b/compos/src/compsvc_worker.rs
@@ -18,94 +18,29 @@
//! responsible for setting up the execution environment, e.g. to create file descriptors for
//! remote file access via an authfs mount.
+mod authfs;
+
use anyhow::{bail, Result};
-use log::warn;
use minijail::Minijail;
-use nix::sys::statfs::{statfs, FsType};
-use std::fs::{File, OpenOptions};
-use std::io;
+use std::fs::File;
use std::os::unix::io::AsRawFd;
use std::path::Path;
use std::process::exit;
-use std::thread::sleep;
-use std::time::{Duration, Instant};
-const AUTHFS_BIN: &str = "/system/bin/authfs";
-const AUTHFS_SETUP_POLL_INTERVAL_MS: Duration = Duration::from_millis(50);
-const AUTHFS_SETUP_TIMEOUT_SEC: Duration = Duration::from_secs(10);
-const FUSE_SUPER_MAGIC: FsType = FsType(0x65735546);
+use crate::authfs::{AuthFs, InFdAnnotation, OutFdAnnotation, PseudoRawFd};
-/// The number that hints the future file descriptor. These are not really file descriptor, but
-/// represents the file descriptor number to pass to the task.
-type PseudoRawFd = i32;
-
-fn is_fuse(path: &str) -> Result<bool> {
- Ok(statfs(path)?.filesystem_type() == FUSE_SUPER_MAGIC)
-}
-
-fn spawn_authfs(config: &Config) -> Result<Minijail> {
- // TODO(b/185175567): Run in a more restricted sandbox.
- let jail = Minijail::new()?;
-
- let mut args = vec![
- AUTHFS_BIN.to_string(),
- config.authfs_root.clone(),
- "--cid=2".to_string(), // Always use host unless we need to support other cases
- ];
- for conf in &config.in_fds {
- // TODO(b/185178698): Many input files need to be signed and verified.
- // or can we use debug cert for now, which is better than nothing?
- args.push("--remote-ro-file-unverified".to_string());
- args.push(format!("{}:{}:{}", conf.fd, conf.fd, conf.file_size));
- }
- for conf in &config.out_fds {
- args.push("--remote-new-rw-file".to_string());
- args.push(format!("{}:{}", conf.fd, conf.fd));
- }
-
- let preserve_fds = if config.debuggable {
- vec![1, 2] // inherit/redirect stdout/stderr for debugging
- } else {
- vec![]
- };
-
- let _pid = jail.run(Path::new(AUTHFS_BIN), &preserve_fds, &args)?;
- Ok(jail)
-}
-
-fn wait_until_authfs_ready(authfs_root: &str) -> Result<()> {
- let start_time = Instant::now();
- loop {
- if is_fuse(authfs_root)? {
- break;
- }
- if start_time.elapsed() > AUTHFS_SETUP_TIMEOUT_SEC {
- bail!("Time out mounting authfs");
- }
- sleep(AUTHFS_SETUP_POLL_INTERVAL_MS);
- }
- Ok(())
-}
-
-fn open_authfs_file(authfs_root: &str, basename: PseudoRawFd, writable: bool) -> io::Result<File> {
- OpenOptions::new().read(true).write(writable).open(format!("{}/{}", authfs_root, basename))
-}
-
-fn open_authfs_files_for_mapping(config: &Config) -> io::Result<Vec<(File, PseudoRawFd)>> {
+fn open_authfs_files_for_mapping(
+ authfs: &AuthFs,
+ config: &Config,
+) -> Result<Vec<(File, PseudoRawFd)>> {
let mut fd_mapping = Vec::with_capacity(config.in_fds.len() + config.out_fds.len());
- let results: io::Result<Vec<_>> = config
- .in_fds
- .iter()
- .map(|conf| Ok((open_authfs_file(&config.authfs_root, conf.fd, false)?, conf.fd)))
- .collect();
+ let results: Result<Vec<_>> =
+ config.in_fds.iter().map(|conf| Ok((authfs.open_file(conf.fd, false)?, conf.fd))).collect();
fd_mapping.append(&mut results?);
- let results: io::Result<Vec<_>> = config
- .out_fds
- .iter()
- .map(|conf| Ok((open_authfs_file(&config.authfs_root, conf.fd, true)?, conf.fd)))
- .collect();
+ let results: Result<Vec<_>> =
+ config.out_fds.iter().map(|conf| Ok((authfs.open_file(conf.fd, true)?, conf.fd))).collect();
fd_mapping.append(&mut results?);
Ok(fd_mapping)
@@ -125,15 +60,6 @@
Ok(jail)
}
-struct InFdAnnotation {
- fd: PseudoRawFd,
- file_size: u64,
-}
-
-struct OutFdAnnotation {
- fd: PseudoRawFd,
-}
-
struct Config {
authfs_root: String,
in_fds: Vec<InFdAnnotation>,
@@ -209,23 +135,19 @@
let config = parse_args()?;
- let authfs_jail = spawn_authfs(&config)?;
- let authfs_lifetime = scopeguard::guard(authfs_jail, |authfs_jail| {
- if let Err(e) = authfs_jail.kill() {
- if !matches!(e, minijail::Error::Killed(_)) {
- warn!("Failed to kill authfs: {}", e);
- }
- }
- });
-
- wait_until_authfs_ready(&config.authfs_root)?;
- let fd_mapping = open_authfs_files_for_mapping(&config)?;
+ let authfs = AuthFs::mount_and_wait(
+ &config.authfs_root,
+ &config.in_fds,
+ &config.out_fds,
+ config.debuggable,
+ )?;
+ let fd_mapping = open_authfs_files_for_mapping(&authfs, &config)?;
let jail = spawn_jailed_task(&config, fd_mapping)?;
let jail_result = jail.wait();
// Be explicit about the lifetime, which should last at least until the task is finished.
- drop(authfs_lifetime);
+ drop(authfs);
match jail_result {
Ok(_) => Ok(()),