Revert "su: allocate new pty (#1693)"

This reverts commit 935dc18faa.

userspace/ksud/src/cli.rs

@@ -1,6 +1,6 @@
 use anyhow::{Ok, Result};
 use clap::Parser;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 
 #[cfg(target_os = "android")]
 use android_logger::Config;
@@ -283,7 +283,7 @@ pub fn run() -> Result<()> {
 
     // the kernel executes su with argv[0] = "su" and replace it with us
     let arg0 = std::env::args().next().unwrap_or_default();
-    if Path::new(&arg0).file_name().and_then(|f| f.to_str()) == Some("su") {
+    if arg0 == "su" || arg0 == "/system/bin/su" {
         return crate::su::root_shell();
     }
 

userspace/ksud/src/defs.rs

@@ -43,5 +43,3 @@ pub const VERSION_NAME: &str = include_str!(concat!(env!("OUT_DIR"), "/VERSION_N
 pub const KSU_BACKUP_DIR: &str = WORKING_DIR;
 pub const KSU_BACKUP_FILE_PREFIX: &str = "ksu_backup_";
 pub const BACKUP_FILENAME: &str = "stock_image.sha1";
-
-pub const PTS_NAME: &str = "pts";

userspace/ksud/src/init_event.rs

@@ -2,7 +2,6 @@ use anyhow::{bail, Context, Result};
 use log::{info, warn};
 use std::{collections::HashMap, path::Path};
 
-use crate::defs::PTS_NAME;
 use crate::module::prune_modules;
 use crate::{
     assets, defs, ksucalls, mount, restorecon,
@@ -194,11 +193,6 @@ pub fn on_post_data_fs() -> Result<()> {
     // mount temp dir
     if let Err(e) = mount::mount_tmpfs(utils::get_tmp_path()) {
         warn!("do temp dir mount failed: {}", e);
-    } else {
-        let pts_dir = format!("{}/{PTS_NAME}", utils::get_tmp_path());
-        if let Err(e) = mount::mount_devpts(pts_dir) {
-            warn!("do devpts mount failed: {}", e);
-        }
     }
 
     // exec modules post-fs-data scripts

userspace/ksud/src/main.rs

@@ -9,8 +9,6 @@ mod ksucalls;
 mod module;
 mod mount;
 mod profile;
-#[cfg(any(target_os = "linux", target_os = "android"))]
-mod pty;
 mod restorecon;
 mod sepolicy;
 mod su;

userspace/ksud/src/mount.rs

@@ -1,5 +1,4 @@
 use anyhow::{anyhow, bail, Ok, Result};
-use std::fs::create_dir;
 
 #[cfg(any(target_os = "linux", target_os = "android"))]
 use anyhow::Context;
@@ -182,19 +181,6 @@ pub fn mount_tmpfs(dest: impl AsRef<Path>) -> Result<()> {
     Ok(())
 }
 
-#[cfg(any(target_os = "linux", target_os = "android"))]
-pub fn mount_devpts(dest: impl AsRef<Path>) -> Result<()> {
-    create_dir(dest.as_ref())?;
-    mount(
-        KSU_OVERLAY_SOURCE,
-        dest.as_ref(),
-        "devpts",
-        MountFlags::empty(),
-        "newinstance",
-    )?;
-    Ok(())
-}
-
 #[cfg(any(target_os = "linux", target_os = "android"))]
 pub fn bind_mount(from: impl AsRef<Path>, to: impl AsRef<Path>) -> Result<()> {
     info!(
@@ -339,8 +325,3 @@ pub fn mount_overlay(
 pub fn mount_tmpfs(_dest: impl AsRef<Path>) -> Result<()> {
     unimplemented!()
 }
-
-#[cfg(not(any(target_os = "linux", target_os = "android")))]
-pub fn mount_devpts(_dest: impl AsRef<Path>) -> Result<()> {
-    unimplemented!()
-}

userspace/ksud/src/pty.rs

@@ -1,195 +0,0 @@
-use std::ffi::c_int;
-use std::fs::File;
-use std::io::{stderr, stdin, stdout, Error, ErrorKind, Read, Write};
-use std::mem::MaybeUninit;
-use std::os::fd::{AsFd, AsRawFd, OwnedFd, RawFd};
-use std::process::exit;
-use std::ptr::null_mut;
-use std::thread;
-
-use anyhow::{bail, Ok, Result};
-use libc::{
-    fork, pthread_sigmask, sigaddset, sigemptyset, sigset_t, sigwait, waitpid, winsize, SIGWINCH,
-    SIG_BLOCK, SIG_UNBLOCK, TIOCGWINSZ, TIOCSWINSZ,
-};
-use rustix::fs::{open, Mode, OFlags};
-use rustix::io::dup;
-use rustix::ioctl::{ioctl, Getter, ReadOpcode};
-use rustix::process::setsid;
-use rustix::pty::{grantpt, unlockpt};
-use rustix::stdio::{dup2_stderr, dup2_stdin, dup2_stdout};
-use rustix::termios::{isatty, tcgetattr, tcsetattr, OptionalActions, Termios};
-
-use crate::defs::PTS_NAME;
-use crate::utils::get_tmp_path;
-
-// https://github.com/topjohnwu/Magisk/blob/5627053b7481618adfdf8fa3569b48275589915b/native/src/core/su/pts.cpp
-
-fn get_pty_num<F: AsFd>(fd: F) -> Result<u32> {
-    Ok(unsafe {
-        let tiocgptn = Getter::<ReadOpcode<b'T', 0x30, u32>, u32>::new();
-        ioctl(fd, tiocgptn)?
-    })
-}
-
-static mut OLD_STDIN: Option<Termios> = None;
-
-fn watch_sigwinch_async(slave: RawFd) {
-    let mut winch = MaybeUninit::<sigset_t>::uninit();
-    unsafe {
-        sigemptyset(winch.as_mut_ptr());
-        sigaddset(winch.as_mut_ptr(), SIGWINCH);
-        pthread_sigmask(SIG_BLOCK, winch.as_mut_ptr(), null_mut());
-    }
-
-    thread::spawn(move || unsafe {
-        let mut winch = MaybeUninit::<sigset_t>::uninit();
-        sigemptyset(winch.as_mut_ptr());
-        sigaddset(winch.as_mut_ptr(), SIGWINCH);
-        pthread_sigmask(SIG_UNBLOCK, winch.as_mut_ptr(), null_mut());
-        let mut sig: c_int = 0;
-        loop {
-            let mut w = MaybeUninit::<winsize>::uninit();
-            if libc::ioctl(1, TIOCGWINSZ, w.as_mut_ptr()) < 0 {
-                continue;
-            }
-            libc::ioctl(slave, TIOCSWINSZ, w.as_mut_ptr());
-            if sigwait(winch.as_mut_ptr(), &mut sig) != 0 {
-                break;
-            }
-        }
-    });
-}
-
-fn set_stdin_raw() {
-    let mut termios = match tcgetattr(stdin()) {
-        Result::Ok(termios) => {
-            unsafe {
-                OLD_STDIN = Some(termios.clone());
-            }
-            termios
-        }
-        Err(_) => return,
-    };
-
-    termios.make_raw();
-
-    if tcsetattr(stdin(), OptionalActions::Flush, &termios).is_err() {
-        let _ = tcsetattr(stdin(), OptionalActions::Drain, &termios);
-    }
-}
-
-fn restore_stdin() {
-    let Some(termios) = (unsafe { OLD_STDIN.take() }) else {
-        return;
-    };
-
-    if tcsetattr(stdin(), OptionalActions::Flush, &termios).is_err() {
-        let _ = tcsetattr(stdin(), OptionalActions::Drain, &termios);
-    }
-}
-
-fn pump<R: Read, W: Write>(mut from: R, mut to: W) {
-    let mut buf = [0u8; 4096];
-    loop {
-        match from.read(&mut buf) {
-            Result::Ok(len) => {
-                if len == 0 {
-                    return;
-                }
-                if to.write_all(&buf[0..len]).is_err() {
-                    return;
-                }
-                if to.flush().is_err() {
-                    return;
-                }
-            }
-            Err(_) => {
-                return;
-            }
-        }
-    }
-}
-
-fn pump_stdin_async(mut ptmx: File) {
-    set_stdin_raw();
-
-    thread::spawn(move || {
-        let mut stdin = stdin();
-        pump(&mut stdin, &mut ptmx);
-    });
-}
-
-fn pump_stdout_blocking(mut ptmx: File) {
-    let mut stdout = stdout();
-    pump(&mut ptmx, &mut stdout);
-
-    restore_stdin();
-}
-
-fn create_transfer(ptmx: OwnedFd) -> Result<()> {
-    let pid = unsafe { fork() };
-    match pid {
-        d if d < 0 => bail!("fork"),
-        0 => return Ok(()),
-        _ => {}
-    }
-
-    let ptmx_r = ptmx;
-    let ptmx_w = dup(&ptmx_r).unwrap();
-
-    let ptmx_r = File::from(ptmx_r);
-    let ptmx_w = File::from(ptmx_w);
-
-    watch_sigwinch_async(ptmx_w.as_raw_fd());
-    pump_stdin_async(ptmx_r);
-    pump_stdout_blocking(ptmx_w);
-
-    let mut status: c_int = -1;
-
-    unsafe {
-        loop {
-            if waitpid(pid, &mut status, 0) == -1 {
-                let last_os_error = Error::last_os_error();
-                if last_os_error.kind() != ErrorKind::Interrupted {
-                    continue;
-                }
-            }
-            break;
-        }
-    }
-
-    exit(status)
-}
-
-pub fn prepare_pty() -> Result<()> {
-    let tty_in = isatty(stdin());
-    let tty_out = isatty(stdout());
-    let tty_err = isatty(stderr());
-    if !tty_in && !tty_out && !tty_err {
-        return Ok(());
-    }
-
-    let mut pts_path = format!("{}/{}", get_tmp_path(), PTS_NAME);
-    if !std::path::Path::new(&pts_path).exists() {
-        pts_path = "/dev/pts".to_string();
-    }
-    let ptmx_path = format!("{}/ptmx", pts_path);
-    let ptmx_fd = open(ptmx_path, OFlags::RDWR, Mode::empty())?;
-    grantpt(&ptmx_fd)?;
-    unlockpt(&ptmx_fd)?;
-    let pty_num = get_pty_num(&ptmx_fd)?;
-    create_transfer(ptmx_fd)?;
-    setsid()?;
-    let pty_fd = open(format!("{pts_path}/{pty_num}"), OFlags::RDWR, Mode::empty())?;
-    if tty_in {
-        dup2_stdin(&pty_fd)?;
-    }
-    if tty_out {
-        dup2_stdout(&pty_fd)?;
-    }
-    if tty_err {
-        dup2_stderr(&pty_fd)?;
-    }
-    Ok(())
-}

userspace/ksud/src/su.rs

@@ -11,8 +11,6 @@ use crate::{
     utils::{self, umask},
 };
 
-#[cfg(any(target_os = "linux", target_os = "android"))]
-use crate::pty::prepare_pty;
 #[cfg(any(target_os = "linux", target_os = "android"))]
 use rustix::{
     process::getuid,
@@ -140,7 +138,6 @@ pub fn root_shell() -> Result<()> {
         "Specify a supplementary group. The first specified supplementary group is also used as a primary group if the option -g is not specified.",
         "GROUP",
     );
-    opts.optflag("", "no-pty", "Do not allocate a new pseudo terminal.");
 
     // Replace -cn with -z, -mm with -M for supporting getopt_long
     let args = args
@@ -268,13 +265,6 @@ pub fn root_shell() -> Result<()> {
         command = command.env("ENV", defs::KSURC_PATH);
     }
 
-    #[cfg(target_os = "android")]
-    if !matches.opt_present("no-pty") {
-        if let Err(e) = prepare_pty() {
-            log::error!("failed to prepare pty: {:?}", e);
-        }
-    }
-
     // escape from the current cgroup and become session leader
     // WARNING!!! This cause some root shell hang forever!
     // command = command.process_group(0);