Isolate interactive terminal session ownership

crates/lazaret-linux/src/process.rs

@@ -33,6 +33,7 @@ pub struct TargetCommand {
     parent_edge: ParentEdge,
     executable: Option<OwnedFd>,
     stdin: Option<File>,
+    terminal: bool,
 }
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
@@ -106,6 +107,7 @@ impl TargetCommand {
             parent_edge: ParentEdge::ParentDeathKill,
             executable: None,
             stdin: None,
+            terminal: false,
         }
     }
 
@@ -124,6 +126,7 @@ impl TargetCommand {
             parent_edge: ParentEdge::ParentDeathKill,
             executable: Some(executable),
             stdin: None,
+            terminal: false,
         })
     }
 
@@ -156,6 +159,12 @@ impl TargetCommand {
         Ok(self)
     }
 
+    #[must_use]
+    pub fn with_controlling_terminal(mut self) -> Self {
+        self.terminal = true;
+        self
+    }
+
     #[must_use]
     pub const fn parent_edge(&self) -> ParentEdge {
         self.parent_edge
@@ -180,6 +189,7 @@ impl TargetCommand {
                 ParentEdge::ParentDeathKill => "kill",
                 ParentEdge::LifetimePipe => "lifetime-pipe",
             })
+            .args(self.terminal.then_some("--target-terminal"))
             .args(
                 self.stdin
                     .as_ref()

crates/lazaret-linux/src/process/broker.rs

@@ -16,6 +16,7 @@ use super::{
 use crate::ipc::private_stream_pair;
 use crate::user_namespace::UserNamespaceMap;
 use std::io::{Read as _, Write as _};
+use std::os::unix::process::CommandExt as _;
 
 impl ChildBroker {
     /// Spawns the private Host Coordinator bootstrap with exact pipe ownership and pidfd reaping.
@@ -44,7 +45,8 @@ impl ChildBroker {
             .args(&target.arguments)
             .stdin(Stdio::from(lifetime_reader))
             .stdout(Stdio::piped())
-            .stderr(Stdio::inherit());
+            .stderr(Stdio::inherit())
+            .process_group(0);
         let mut child = command.spawn()?;
         let status = child
             .stdout
@@ -743,6 +745,7 @@ fn run_mapped_wrapper_role(arguments: Vec<OsString>) -> io::Result<()> {
         rustix::process::Uid::ROOT,
         rustix::process::Uid::ROOT,
     )?;
+    establish_controlling_terminal(&target)?;
     if let Some(stdin) = target.stdin.as_ref() {
         rustix::stdio::dup2_stdin(stdin)?;
     }
@@ -761,12 +764,27 @@ fn run_wrapper_role(arguments: Vec<OsString>) -> io::Result<()> {
             require_lifetime_pipe_and_recheck(expected_parent)?;
         }
     }
+    establish_controlling_terminal(&target)?;
     if let Some(stdin) = target.stdin.as_ref() {
         rustix::stdio::dup2_stdin(stdin)?;
     }
     Err(exec_target(target))
 }
 
+fn establish_controlling_terminal(target: &TargetCommand) -> io::Result<()> {
+    if !target.terminal {
+        return Ok(());
+    }
+    let stdin = target
+        .stdin
+        .as_ref()
+        .ok_or_else(|| io::Error::other("terminal target stdin is missing"))?;
+    rustix::process::setsid()?;
+    rustix::process::ioctl_tiocsctty(stdin)?;
+    rustix::termios::tcsetpgrp(stdin, rustix::process::getpgrp())?;
+    Ok(())
+}
+
 fn require_lifetime_pipe_and_recheck(
     expected_parent: PidfsProcessIdentityV1,
 ) -> io::Result<RetainedProcess> {

crates/lazaret-linux/src/process/launch.rs

@@ -91,7 +91,11 @@ pub fn parse_wrapper_arguments(
         Some("lifetime-pipe") => ParentEdge::LifetimePipe,
         _ => return Err(io::Error::other("wrapper parent action is invalid")),
     };
-    let next = arguments.next();
+    let mut next = arguments.next();
+    let terminal = next.as_deref() == Some(OsStr::new("--target-terminal"));
+    if terminal {
+        next = arguments.next();
+    }
     let stdin = if next.as_deref() == Some(OsStr::new("--target-stdin-fd")) {
         let descriptor = arguments
             .next()
@@ -117,6 +121,7 @@ pub fn parse_wrapper_arguments(
         parent_edge,
         executable: None,
         stdin,
+        terminal,
     };
     let boot = parse_boot_hex(&boot)?;
     Ok((