implemented, no test

README.md

@@ -0,0 +1,25 @@
+# ADBD Guard
+
+A daemon for aarch64 android to monitor on tcp stream of adbd and notify if suspicious actions are detected.
+
+NOTE: some part of libs may not available, so try dev on linux.
+
+
+## Build
+
+### Install Cargo NDK
+```bash
+cargo install cargo-ndk
+```
+
+### Install NDK
+```
+https://developer.android.com/ndk/downloads
+```
+
+### Build Script
+
+```bash
+#!/bin/bash
+ANDROID_NDK_HOME=/path/to/ndk_top_level cargo ndk --platform 30 -t aarch64-linux-android build --release
+```

adbdguard.json

@@ -0,0 +1,51 @@
+{
+    "debounce_ms": 3000,
+    "max_payload_peek": 256,
+    "broadcast_action": "com.adbguard.ALERT",
+    "rules": [
+        {
+            "name": "exec_any",
+            "when": "service",
+            "contains": [
+                "exec:"
+            ]
+        },
+        {
+            "name": "danger_shell",
+            "when": "service",
+            "contains": [
+                "shell:"
+            ],
+            "patterns": "(su|setenforce|mount|dd|pm\\s+grant|appops|iptables|chcon)\\b"
+        },
+        {
+            "name":"abb_pm",
+            "when": "service",
+            "contains": [
+                "abb_exec:pm "
+            ]
+        },
+        {
+            "name": "sync_sensitive",
+            "when": "service",
+            "contains": [
+                "sync:"
+            ],
+            "patterns": "/(system|vendor|data/system|data/adb)/"
+        },
+        {
+            "name": "remount",
+            "when": "service",
+            "contains": [
+                "remount"
+            ]
+        },
+        {
+            "name": "tcpip",
+            "when":"service",
+            "contains": [
+                "tcpip:"
+            ]
+        }
+    ]
+}

src/backend/mod.rs

@@ -1,2 +1,2 @@
-#[cfg(all(feature = "ptrace", target_arch = "aarch64"))]
+
 pub mod ptrace;

src/backend/ptrace.rs

@@ -11,19 +11,163 @@ use nix::{
     unistd::Pid,
 };
 use std::{
-    collections::HashMap,
-    time::{Duration, Instant},
+    collections::HashMap, hash::Hash, time::{Duration, Instant}
 };
 
-const PTRACE_GETREGSET_FALLBACK: i32 = 0x4204;
-const NT_PRSTATUS_FALLBACK: i32 = 1;
+const PTRACE_GETREGSET_FALLBACK: libc::c_int = 0x4204;
+const PTRACE_SEIZE_FALLBACK: libc::c_int = 0x4206;
+const PTRACE_INTERRUPT: libc::c_int = 0x4207;
+const NT_PRSTATUS_FALLBACK: libc::c_int = 1;
+
 
-#[cfg(target_arch = "aarch64")]
 #[repr(C)]
 #[derive(Clone, Copy, Default)]
-struct UserAtRegs {
+struct UserPtRegs {
     regs: [u64; 31],
     sp: u64,
     pc: u64,
     pstate: u64,
 }
+
+fn get_regs(pid: Pid) -> Result<UserPtRegs> {
+    let mut regs = UserPtRegs::default();
+    unsafe {
+        let r = libc::ptrace(
+            PTRACE_GETREGSET_FALLBACK.try_into().unwrap(),
+            pid.as_raw(),
+            NT_PRSTATUS_FALLBACK,
+            &mut regs as *mut _,
+        );
+        if r < 0 {
+            return Err(anyhow::anyhow!("GETREGSET failed"));
+        }
+    }
+    Ok(regs)
+}
+
+// x8 holds syscall
+fn syscall_no(regs: &UserPtRegs) -> u64 {
+    regs.regs[8]
+}
+
+// x0 1st arg
+fn arg0(regs: &UserPtRegs) -> u64 {
+    regs.regs[0]
+}
+
+// x1 buf/count
+fn arg1(regs: &UserPtRegs) -> u64 {
+    regs.regs[1]
+}
+
+fn arg2(regs: &UserPtRegs) -> u64 {
+    regs.regs[2]
+}
+
+const SYS_write: u64 = 64;
+const SYS_sendto: u64 = 206;
+const SYS_read: u64 = 63;
+const SYS_recvfrom: u64 = 207;
+
+struct ConnState {
+    buf: BytesMut,
+    last_alert: Instant
+}
+
+impl ConnState {
+    fn new() -> Self {
+        Self {
+            buf: BytesMut::with_capacity(4096),
+            last_alert: Instant::now() - Duration::from_secs(3600)
+        }
+    }
+}
+
+unsafe fn ptrace_cmd(cmd: libc::c_int, pid: Pid, addr: usize) -> nix::Result<()> {
+    let mut regs = UserPtRegs::default(); 
+    let r = unsafe { libc::ptrace(cmd.try_into().unwrap(), pid.as_raw(), addr as *mut libc::c_int, &mut regs as *mut _) };
+    if r == -1 {
+        return Err(nix::errno::Errno::last());
+    }
+
+    Ok(())
+}
+
+pub fn run(pid: i32, rules: RuleSet, action: String, debounce: Duration, peek: usize) -> Result<()> {
+    let pid = Pid::from_raw(pid);
+    // cannot compiled
+    // ptrace::seize(pid, ptrace::Options::PTRACE_O_TRACESYSGOOD)?; 
+
+    unsafe {
+        ptrace_cmd(PTRACE_SEIZE_FALLBACK.try_into().unwrap(), pid, 0)?;
+    }
+
+    // cannot compiled
+    // ptrace::interrupt(pid)?;
+
+    unsafe {
+        ptrace_cmd(PTRACE_INTERRUPT.try_into().unwrap(), pid, 0)?;
+    }
+
+    waitpid(pid, None);
+
+    let mut conns: HashMap<i32, ConnState> = HashMap::new();
+
+    loop {
+        ptrace::syscall(pid, None)?;
+        let st = waitpid(pid, Some(WaitPidFlag::__WALL))?;
+        let WSIG = |ws: &WaitStatus| matches!(ws, WaitStatus::PtraceSyscall(_));
+        if !WSIG(&st){continue;}
+
+        // syscall entry
+        let regs = get_regs(pid)?;
+        let scn = syscall_no(&regs);
+        let is_out = scn == SYS_write || scn == SYS_sendto;
+        let is_in = scn == SYS_read || scn == SYS_recvfrom;
+        if !(is_in || is_out){
+            continue;
+        }
+
+        let fd = arg0(&regs) as i32;
+        let buf_ptr = if is_out {
+            arg1(&regs)
+        } else {
+            arg0(&regs)
+        };
+        let count = if is_out {
+            arg2(&regs)
+        } else {
+            arg1(&regs)
+        } as usize;
+        let take = count.min(peek);
+
+        // syscall run to exit, return value
+        ptrace::syscall(pid, None)?;
+        let _ = waitpid(pid, Some(WaitPidFlag::__WALL))?;
+
+        // copy user buffer
+        if take > 0 {
+            let mut data = vec![0u8; take];
+            let local_iov = libc::iovec { iov_base: data.as_mut_ptr() as *mut _,  iov_len: take};
+            let remote_iov = libc::iovec { iov_base: buf_ptr as *mut _, iov_len: take};
+            unsafe {
+                let n = libc::process_vm_readv(pid.as_raw(), &local_iov as *const _, 1, &remote_iov as *const _, 1, 0);
+                if n as isize <= 0 {continue;}
+            }
+            let s = conns.entry(fd).or_insert_with(ConnState::new);
+            s.buf.extend_from_slice(&data);
+
+            while let Some(frame) = adb::try_parse(&mut s.buf){
+                if frame.cmd == adb::CMD_OPEN {
+                    let service = String::from_utf8_lossy(&frame.payload).to_string();
+                    if let Some(rule) = rules.match_service(&service) {
+                        if s.last_alert.elapsed() >= debounce {
+                            broadcaster::broadcast(&action, &service, rule);
+                            s.last_alert = Instant::now();
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

src/main.rs

@@ -1,9 +1,72 @@
+use std::{path::PathBuf, sync::{Arc, Mutex}, time::Duration};
+
+
+use config::Config;
+use notify::{RecommendedWatcher, Watcher};
+use rule::RuleSet;
+use tracing::{info, error};
+use tracing_subscriber::FmtSubscriber;
+
 mod adb;
 mod backend;
 mod broadcaster;
 mod config;
 mod rule;
 
-fn main() {
-    println!("Hello, world!");
+fn pidof(name: &str) -> Option<i32> {
+    let out = std::process::Command::new("pidof").arg(name).output().ok()?;
+    let s = String::from_utf8_lossy(&out.stdout).trim().to_string();
+    s.split_whitespace().next()?.parse::<i32>().ok()
+}
+
+fn watch_config(path: PathBuf, cfg: Arc<Mutex<Config>>) -> notify::Result<RecommendedWatcher> {
+    let saved_path = path.clone();
+    let mut w = notify::recommended_watcher(move |res: Result<notify::Event, _>| {
+        if let Ok(event) = res {
+            if event.kind.is_modify() {
+                if let Ok(newc) = Config::load(path.clone().to_str().unwrap()){
+                    *cfg.lock().unwrap() = newc;
+                }
+            }
+        }
+    })?;
+    w.watch(&saved_path, notify::RecursiveMode::NonRecursive)?;
+    Ok(w)
+}
+
+fn main() -> anyhow::Result<()> {
+    let sub = FmtSubscriber::builder().without_time().with_target(false).finish();
+    tracing::subscriber::set_global_default(sub).ok();
+
+    let mut args = std::env::args().skip(1);
+    let cfg_path = args.next().filter(|s| s=="--config").and_then(|_| args.next()).unwrap_or_else(|| "/data/adb/modules/adbguard/adbguard.json".into());
+    let cfg0 = Config::load(&cfg_path)?;
+    let cfg = Arc::new(Mutex::new(cfg0));
+    let _w = watch_config((&cfg_path).into(), cfg.clone()).ok();
+
+    loop {
+        let pid = loop {
+            if let Some(p) = pidof("adbd"){
+                break p;
+            }
+            std::thread::sleep(Duration::from_secs(1));
+        };
+
+        info!("attaching to adbd {}", pid);
+
+        let snapshot = {
+            cfg.lock().unwrap().clone()
+        };
+        let rules = RuleSet::from_cfg(&snapshot);
+        let action = snapshot.broadcast_action.clone();
+
+        #[cfg(feature = "ptrace")]
+        {
+            if let Err(e) = backend::ptrace::run(pid, rules, action, snapshot.debounce(), snapshot.max_payload_peek){
+                error!("backend exited, {e:?}");
+            }
+        }
+        std::thread::sleep(Duration::from_secs(1));
+        
+    }
 }