Separate companion

README.md

@@ -12,11 +12,7 @@ Warning: The current version of Zygisksu is UNSTABLE. You may suffer boot loop o
 
 ## Compatibility
 
-- [x] LSPosed
-- [x] Storage Isolation
-- [ ] IFW Enhance
-- [ ] Universal SafetyNet Fix
-- [ ] Shamiko
+Should work with everything except those rely on Magisk internal behaviors.
 
 ## Development road map
 
@@ -24,8 +20,8 @@ Warning: The current version of Zygisksu is UNSTABLE. You may suffer boot loop o
 - [x] [Inject] Stabilize injector
 - [x] [Inject] Unload
 - [x] [Daemon] Linker namespace
-- [ ] [Daemon] Separate zygiskd process
-- [ ] [Daemon] Handle 64 bit only devices
+- [x] [Daemon] Separate zygiskd process
+- [x] [Daemon] Handle 64 bit only devices
 - [ ] [Daemon] Handle zygote death
 
 ## Running on Magisk

loader/src/common/daemon.cpp

@@ -98,10 +98,6 @@ namespace zygiskd {
         }
         socket_utils::write_u8(fd, (uint8_t) SocketAction::GetModuleDir);
         socket_utils::write_usize(fd, index);
-        if (socket_utils::read_u8(fd) == 1) {
-            return fd;
-        } else {
-            return -1;
-        }
+        return socket_utils::recv_fd(fd);
     }
 }

module/src/daemon.sh

@@ -9,4 +9,4 @@ export NATIVE_BRIDGE=$(getprop ro.dalvik.vm.native.bridge)
 
 log -p i -t "zygisksu" "Start watchdog"
 resetprop ro.dalvik.vm.native.bridge libzygiskloader.so
-exec "$MODDIR/bin/zygiskwd" >/dev/null 2>&1
+exec "$MODDIR/bin/zygiskwd" "watchdog" >/dev/null 2>&1

zygiskd/Cargo.toml

@@ -8,6 +8,7 @@ rust-version = "1.67"
 [dependencies]
 android_logger = "0.12.0"
 anyhow = { version = "1.0.68", features = ["backtrace"] }
+clap = { version = "4.1.4", features = ["derive"] }
 const_format = "0.2.5"
 log = "0.4.17"
 memfd = "0.6.2"

zygiskd/build.gradle.kts

@@ -3,6 +3,9 @@ plugins {
     id("org.mozilla.rust-android-gradle.rust-android")
 }
 
+val verName: String by rootProject.extra
+val verCode: Int by rootProject.extra
+
 android.buildFeatures {
     androidResources = false
     buildConfig = false
@@ -16,4 +19,8 @@ cargo {
     targetDirectory = "build/intermediates/rust"
     val isDebug = gradle.startParameter.taskNames.any { it.toLowerCase().contains("debug") }
     profile = if (isDebug) "debug" else "release"
+    exec = { spec, _ ->
+        spec.environment("VERSION_CODE", verCode)
+        spec.environment("VERSION_NAME", verName)
+    }
 }

zygiskd/src/companion.rs

@@ -0,0 +1,61 @@
+use std::ffi::c_void;
+use std::os::fd::{FromRawFd, RawFd};
+use std::os::unix::net::UnixStream;
+use std::thread;
+use anyhow::Result;
+use nix::libc;
+use passfd::FdPassingExt;
+use crate::utils::UnixStreamExt;
+use crate::dl;
+
+type ZygiskCompanionEntryFn = unsafe extern "C" fn(i32);
+
+pub fn entry(fd: i32) -> Result<()> {
+    unsafe { libc::prctl(libc::PR_SET_PDEATHSIG, libc::SIGKILL) };
+    let mut stream = unsafe { UnixStream::from_raw_fd(fd) };
+    let name = stream.read_string()?;
+    let library = stream.recv_fd()?;
+    let entry = load_module(library)?;
+    unsafe { libc::close(library) };
+
+    let entry = match entry {
+        Some(entry) => {
+            log::debug!("Companion process created for `{name}`");
+            stream.write_u8(1)?;
+            entry
+        }
+        None => {
+            log::debug!("No companion entry for `{name}`");
+            stream.write_u8(0)?;
+            return Ok(());
+        }
+    };
+
+    loop {
+        let fd = stream.recv_fd()?;
+        log::trace!("New companion request from module `{name}`");
+        thread::spawn(move || {
+            unsafe {
+                let mut s = UnixStream::from_raw_fd(fd);
+                match s.write_u8(1) { // Ack
+                    Ok(_) => entry(fd),
+                    Err(_) => log::warn!("Ack failed?"),
+                }
+            };
+        });
+    }
+}
+
+fn load_module(fd: RawFd) -> Result<Option<ZygiskCompanionEntryFn>> {
+    unsafe {
+        let path = format!("/proc/self/fd/{fd}");
+        let handle = dl::dlopen(&path, libc::RTLD_NOW)?;
+        let symbol = std::ffi::CString::new("zygisk_companion_entry")?;
+        let entry = libc::dlsym(handle, symbol.as_ptr());
+        if entry.is_null() {
+            return Ok(None);
+        }
+        let fnptr = std::mem::transmute::<*mut c_void, ZygiskCompanionEntryFn>(entry);
+        Ok(Some(fnptr))
+    }
+}

zygiskd/src/constants.rs

@@ -1,6 +1,27 @@
 use const_format::concatcp;
+use log::LevelFilter;
 use num_enum::TryFromPrimitive;
 
+pub const VERSION_NAME: &str = env!("VERSION_NAME");
+pub const VERSION_CODE: &str = env!("VERSION_CODE");
+pub const VERSION_FULL: &str = concatcp!(VERSION_NAME, " (", VERSION_CODE, ")");
+
+#[cfg(debug_assertions)]
+pub const MAX_LOG_LEVEL: LevelFilter = LevelFilter::Trace;
+#[cfg(not(debug_assertions))]
+pub const MAX_LOG_LEVEL: LevelFilter = LevelFilter::Info;
+
+#[cfg(target_pointer_width = "64")]
+#[macro_export]
+macro_rules! lp_select {
+    ($lp32:expr, $lp64:expr) => { $lp64 };
+}
+#[cfg(target_pointer_width = "32")]
+#[macro_export]
+macro_rules! lp_select {
+    ($lp32:expr, $lp64:expr) => { $lp32 };
+}
+
 pub const PROP_NATIVE_BRIDGE: &str = "ro.dalvik.vm.native.bridge";
 
 pub const SOCKET_PLACEHOLDER: &str = "socket_placeholder";

zygiskd/src/main.rs

@@ -1,57 +1,53 @@
 #![allow(dead_code)]
 
+mod companion;
 mod constants;
 mod dl;
 mod utils;
 mod watchdog;
-mod zygisk;
+mod zygiskd;
 
-use anyhow::{bail, Result};
-use log::LevelFilter;
-use nix::libc;
+use clap::{Subcommand, Parser};
+
+#[derive(Parser, Debug)]
+#[command(author, version = constants::VERSION_FULL, about, long_about = None)]
+struct Args {
+    #[command(subcommand)]
+    command: Commands,
+}
+
+#[derive(Subcommand, Debug)]
+enum Commands {
+    /// Start zygisk watchdog
+    Watchdog,
+    /// Start zygisk daemon
+    Daemon,
+    /// Start zygisk companion
+    Companion { fd: i32 },
+}
 
-#[cfg(debug_assertions)]
-static MAX_LOG_LEVEL: LevelFilter = LevelFilter::Trace;
-#[cfg(not(debug_assertions))]
-static MAX_LOG_LEVEL: LevelFilter = LevelFilter::Info;
 
 fn init_android_logger(tag: &str) {
     android_logger::init_once(
         android_logger::Config::default()
-            .with_max_level(MAX_LOG_LEVEL)
+            .with_max_level(constants::MAX_LOG_LEVEL)
             .with_tag(tag),
     );
 }
 
-fn entry() -> Result<()> {
-    let process = std::env::args().next().unwrap();
-    let process = process.split('/').last().unwrap();
-    init_android_logger(process);
-    match process {
-        "zygiskwd" => {
-            log::info!("Start zygisksu watchdog");
-            watchdog::check_permission()?;
-            watchdog::ensure_single_instance()?;
-            watchdog::spawn_daemon()?;
-        }
-        "zygiskd32" => {
-            log::info!("Start zygiskd32");
-            unsafe { libc::prctl(libc::PR_SET_PDEATHSIG, libc::SIGKILL); }
-            zygisk::start(false)?;
-            loop {}
-        }
-        "zygiskd64" => {
-            log::info!("Start zygiskd64");
-            unsafe { libc::prctl(libc::PR_SET_PDEATHSIG, libc::SIGKILL); }
-            zygisk::start(true)?;
-        }
-        _ => bail!("Unexpected process name: {process}")
-    }
-    Ok(())
-}
-
 fn main() {
-    if let Err(e) = entry() {
+    let process = std::env::args().next().unwrap();
+    let nice_name = process.split('/').last().unwrap();
+    init_android_logger(nice_name);
+
+    let cli = Args::parse();
+    let result = match cli.command {
+        Commands::Watchdog => watchdog::entry(),
+        Commands::Daemon => zygiskd::entry(lp_select!(false, true)),
+        Commands::Companion { fd } => companion::entry(fd),
+    };
+
+    if let Err(e) = &result {
         log::error!("Crashed: {}\n{}", e, e.backtrace());
     }
 }

zygiskd/src/watchdog.rs

@@ -9,7 +9,14 @@ use std::{fs, thread};
 
 static mut LOCK_FILE: Option<fs::File> = None;
 
-pub fn check_permission() -> Result<()> {
+pub fn entry() -> Result<()> {
+    log::info!("Start zygisksu watchdog");
+    check_permission()?;
+    ensure_single_instance()?;
+    spawn_daemon()
+}
+
+fn check_permission() -> Result<()> {
     log::info!("Check permission");
     let uid = getuid();
     if uid.as_raw() != 0 {
@@ -31,7 +38,7 @@ pub fn check_permission() -> Result<()> {
     Ok(())
 }
 
-pub fn ensure_single_instance() -> Result<()> {
+fn ensure_single_instance() -> Result<()> {
     log::info!("Ensure single instance");
     let metadata = fs::metadata(constants::PATH_ZYGISKSU_DIR);
     if metadata.is_err() || !metadata.unwrap().is_dir() {
@@ -50,9 +57,9 @@ pub fn ensure_single_instance() -> Result<()> {
     Ok(())
 }
 
-pub fn spawn_daemon() -> Result<()> {
-    let daemon32 = Command::new(constants::PATH_ZYGISKD32).spawn()?;
-    let daemon64 = Command::new(constants::PATH_ZYGISKD64).spawn()?;
+fn spawn_daemon() -> Result<()> {
+    let daemon32 = Command::new(constants::PATH_ZYGISKD32).arg("daemon").spawn();
+    let daemon64 = Command::new(constants::PATH_ZYGISKD64).arg("daemon").spawn();
     let (sender, receiver) = mpsc::channel();
     let spawn = |mut daemon: Child| {
         let sender = sender.clone();
@@ -63,8 +70,8 @@ pub fn spawn_daemon() -> Result<()> {
             sender.send(()).unwrap();
         });
     };
-    spawn(daemon32);
-    spawn(daemon64);
+    if let Ok(it) = daemon32 { spawn(it) }
+    if let Ok(it) = daemon64 { spawn(it) }
     let _ = receiver.recv();
     bail!("Daemon process died");
 }

zygiskd/src/zygiskd.rs

@@ -1,30 +1,29 @@
 use crate::constants::DaemonSocketAction;
 use crate::utils::{restore_native_bridge, UnixStreamExt};
-use crate::{constants, dl, utils};
+use crate::{constants, utils};
 use anyhow::{bail, Result};
 use memfd::Memfd;
 use nix::{
-    libc::{self, dlsym},
-    unistd::getppid,
+    fcntl::{fcntl, FcntlArg, FdFlag},
+    libc::self,
 };
 use passfd::FdPassingExt;
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 use std::thread;
-use std::ffi::{c_char, c_void};
+use std::ffi::c_char;
 use std::fs;
 use std::os::unix::{
     net::{UnixListener, UnixStream},
     prelude::AsRawFd,
 };
+use std::os::unix::process::CommandExt;
 use std::path::PathBuf;
 use std::process::Command;
 
-type ZygiskCompanionEntryFn = unsafe extern "C" fn(i32);
-
 struct Module {
     name: String,
     memfd: Memfd,
-    companion_entry: Option<ZygiskCompanionEntryFn>,
+    companion: Mutex<Option<UnixStream>>,
 }
 
 struct Context {
@@ -32,8 +31,9 @@ struct Context {
     modules: Vec<Module>,
 }
 
-pub fn start(is64: bool) -> Result<()> {
-    check_parent()?;
+pub fn entry(is64: bool) -> Result<()> {
+    unsafe { libc::prctl(libc::PR_SET_PDEATHSIG, libc::SIGKILL) };
+
     let arch = get_arch(is64)?;
     log::debug!("Daemon architecture: {arch}");
 
@@ -63,15 +63,6 @@ pub fn start(is64: bool) -> Result<()> {
     Ok(())
 }
 
-fn check_parent() -> Result<()> {
-    let parent = fs::read_to_string(format!("/proc/{}/cmdline", getppid().as_raw()))?;
-    let parent = parent.split('/').last().unwrap().trim_end_matches('\0');
-    if parent != "zygiskwd" {
-        bail!("Daemon is not started by watchdog: {parent}");
-    }
-    Ok(())
-}
-
 fn get_arch(is64: bool) -> Result<&'static str> {
     let output = Command::new("getprop").arg("ro.product.cpu.abi").output()?;
     let system_arch = String::from_utf8(output.stdout)?;
@@ -111,18 +102,16 @@ fn load_modules(arch: &str) -> Result<Vec<Module>> {
                 continue;
             }
         };
-        let companion_entry = match preload_module(&memfd) {
-            Ok(entry) => entry,
+        let companion = match spawn_companion(&name, &memfd) {
+            Ok(companion) => companion,
             Err(e) => {
-                log::warn!("  Failed to preload `{name}`: {e}");
+                log::warn!("  Failed to spawn companion for `{name}`: {e}");
                 continue;
             }
         };
-        let module = Module {
-            name,
-            memfd,
-            companion_entry,
-        };
+
+        let companion = Mutex::new(companion);
+        let module = Module { name, memfd, companion };
         modules.push(module);
     }
 
@@ -148,20 +137,6 @@ fn create_memfd(name: &str, so_path: &PathBuf) -> Result<Memfd> {
     Ok(memfd)
 }
 
-fn preload_module(memfd: &Memfd) -> Result<Option<ZygiskCompanionEntryFn>> {
-    unsafe {
-        let path = format!("/proc/self/fd/{}", memfd.as_raw_fd());
-        let handle = dl::dlopen(&path, libc::RTLD_NOW)?;
-        let symbol = std::ffi::CString::new("zygisk_companion_entry")?;
-        let entry = dlsym(handle, symbol.as_ptr());
-        if entry.is_null() {
-            return Ok(None);
-        }
-        let fnptr = std::mem::transmute::<*mut c_void, ZygiskCompanionEntryFn>(entry);
-        Ok(Some(fnptr))
-    }
-}
-
 fn create_daemon_socket(is64: bool) -> Result<UnixListener> {
     utils::set_socket_create_context("u:r:zygote:s0")?;
     let suffix = if is64 { "zygiskd64" } else { "zygiskd32" };
@@ -171,6 +146,29 @@ fn create_daemon_socket(is64: bool) -> Result<UnixListener> {
     Ok(listener)
 }
 
+fn spawn_companion(name: &str, memfd: &Memfd) -> Result<Option<UnixStream>> {
+    let (mut daemon, companion) = UnixStream::pair()?;
+    // Remove FD_CLOEXEC flag
+    fcntl(companion.as_raw_fd(), FcntlArg::F_SETFD(FdFlag::empty()))?;
+
+    let process = std::env::args().next().unwrap();
+    let nice_name = process.split('/').last().unwrap();
+    Command::new(&process)
+        .arg0(format!("{}-{}", nice_name, name))
+        .arg("companion")
+        .arg(format!("{}", companion.as_raw_fd()))
+        .spawn()?;
+    drop(companion);
+
+    daemon.write_string(name)?;
+    daemon.send_fd(memfd.as_raw_fd())?;
+    match daemon.read_u8()? {
+        0 => Ok(None),
+        1 => Ok(Some(daemon)),
+        _ => bail!("Invalid companion response"),
+    }
+}
+
 fn handle_daemon_action(mut stream: UnixStream, context: &Context) -> Result<()> {
     let action = stream.read_u8()?;
     let action = DaemonSocketAction::try_from(action)?;
@@ -207,13 +205,15 @@ fn handle_daemon_action(mut stream: UnixStream, context: &Context) -> Result<()>
         DaemonSocketAction::RequestCompanionSocket => {
             let index = stream.read_usize()?;
             let module = &context.modules[index];
-            log::debug!("New companion request from module {}", module.name);
-
-            // FIXME: Spawn a new process
-            match module.companion_entry {
-                Some(entry) => {
-                    stream.write_u8(1)?;
-                    unsafe { entry(stream.as_raw_fd()); }
+            let mut companion = module.companion.lock().unwrap();
+            match companion.as_ref() {
+                Some(sock) => {
+                    if let Err(_) = sock.send_fd(stream.as_raw_fd()) {
+                        log::error!("Companion of module `{}` crashed", module.name);
+                        companion.take();
+                        stream.write_u8(0)?;
+                    }
+                    // Ok: Send by companion
                 }
                 None => {
                     stream.write_u8(0)?;