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fix(server): allow newlines in exec command arguments #1965

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ac7966f
fix(server): allow newlines in shell_escape for multi-line exec scripts
zanetworker Jun 21, 2026
8a392b2
fix(server): allow newlines in exec command arguments
zanetworker Jun 21, 2026
42e884d
refactor(server): decompose reject_control_chars per reviewer feedback
zanetworker Jun 23, 2026
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41 changes: 33 additions & 8 deletions crates/openshell-server/src/grpc/sandbox.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1457,9 +1457,6 @@ fn shell_escape(value: &str) -> Result<String, String> {
if value.bytes().any(|b| b == 0) {
return Err("value contains null bytes".to_string());
}
if value.bytes().any(|b| b == b'\n' || b == b'\r') {
return Err("value contains newline or carriage return".to_string());
}
if value.is_empty() {

@elezar elezar Jun 23, 2026

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Since this helper now allows \n/\r, the downstream command_preview fields in the exec logging paths should not log the assembled command raw. In line-oriented log sinks, user-controlled CR/LF can split records or create forged-looking continuation lines. Can we escape the preview before logging, and reuse the same helper for both non-interactive and interactive exec?

let command_preview: String = command
    .chars()
    .take(120)
    .flat_map(char::escape_default)
    .collect();

return Ok("''".to_string());
}
Expand Down Expand Up @@ -1998,10 +1995,20 @@ mod tests {
}

#[test]
fn shell_escape_rejects_newlines() {
assert!(shell_escape("line1\nline2").is_err());
assert!(shell_escape("line1\rline2").is_err());
assert!(shell_escape("line1\r\nline2").is_err());
fn shell_escape_allows_newlines() {
assert!(shell_escape("line1\nline2").is_ok());
assert!(shell_escape("line1\rline2").is_ok());
assert!(shell_escape("line1\r\nline2").is_ok());
}

#[test]
fn shell_escape_preserves_newlines_in_single_quotes() {
assert_eq!(shell_escape("line1\nline2").unwrap(), "'line1\nline2'");
assert_eq!(
shell_escape("def f():\n return 1").unwrap(),
"'def f():\n return 1'"
);
assert_eq!(shell_escape("line1\r\nline2").unwrap(), "'line1\r\nline2'");
}

// ---- build_remote_exec_command ----
Expand Down Expand Up @@ -2057,7 +2064,25 @@ mod tests {
workdir: "/tmp\nmalicious".to_string(),
..Default::default()
};
assert!(build_remote_exec_command(&req).is_err());
// Validation layer rejects newlines in workdir
assert!(validate_exec_request_fields(&req).is_err());

@elezar elezar Jun 23, 2026

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nit: This test name still says build_remote_exec_command, but the assertion now exercises validate_exec_request_fields(). Could we rename it to validate_exec_rejects_newlines_in_workdir, or drop it since validation.rs already has this coverage?

}

#[test]
fn build_remote_exec_command_accepts_multiline_script() {
use openshell_core::proto::ExecSandboxRequest;
let req = ExecSandboxRequest {
sandbox_id: "test".to_string(),
command: vec![
"python3".to_string(),
"-c".to_string(),
"def f():\n return 1\nprint(f())".to_string(),

@elezar elezar Jun 23, 2026

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This test should include both CR/LF and a single quote in the same command argument. The risky interaction here is not just that newlines are accepted, but that multiline script text still composes correctly with POSIX single-quote escaping.

For example, something like print('one')\r\nprint('two') would give us regression coverage for the exact case this helper has to keep safe.

],
..Default::default()
};
let cmd = build_remote_exec_command(&req).unwrap();
assert!(cmd.starts_with("python3 -c "));
assert!(cmd.contains("'def f():\n return 1\nprint(f())'"));
}

#[test]
Expand Down
66 changes: 65 additions & 1 deletion crates/openshell-server/src/grpc/validation.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,7 @@ pub(super) fn validate_exec_request_fields(req: &ExecSandboxRequest) -> Result<(
"command argument {i} exceeds {MAX_EXEC_ARG_LEN} byte limit"
)));
}
reject_control_chars(arg, &format!("command argument {i}"))?;
reject_null_bytes(arg, &format!("command argument {i}"))?;
}
for (key, value) in &req.environment {
if value.len() > MAX_EXEC_ARG_LEN {
Expand Down Expand Up @@ -83,6 +83,20 @@ pub(super) fn reject_control_chars(value: &str, field_name: &str) -> Result<(),
Ok(())
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}

/// Reject only null bytes in a user-supplied value.
///
/// Use this for exec command arguments where newlines are legitimate
/// (e.g. multi-line scripts passed to `bash -c` or `python3 -c`).
/// The shell-escape layer handles newline safety via single-quoting.
pub(super) fn reject_null_bytes(value: &str, field_name: &str) -> Result<(), Status> {
if value.bytes().any(|b| b == 0) {
return Err(Status::invalid_argument(format!(
"{field_name} contains null bytes"
)));
}
Ok(())
}

// ---------------------------------------------------------------------------
// Sandbox spec validation
// ---------------------------------------------------------------------------
Expand Down Expand Up @@ -1718,4 +1732,54 @@ mod tests {
assert!(reject_control_chars("line1\nline2", "test").is_err());
assert!(reject_control_chars("line1\rline2", "test").is_err());
}

#[test]
fn validate_exec_allows_newlines_in_command_args() {
let req = ExecSandboxRequest {
sandbox_id: "test".to_string(),
command: vec![
"python3".to_string(),
"-c".to_string(),
"def f():\n return 1\nprint(f())".to_string(),
],
..Default::default()
};
assert!(validate_exec_request_fields(&req).is_ok());
}

#[test]
fn validate_exec_still_rejects_null_bytes_in_command_args() {
let req = ExecSandboxRequest {
sandbox_id: "test".to_string(),
command: vec!["echo".to_string(), "hello\x00world".to_string()],
..Default::default()
};
let err = validate_exec_request_fields(&req).unwrap_err();
assert!(err.message().contains("null"));
}

#[test]
fn validate_exec_still_rejects_newlines_in_workdir() {
let req = ExecSandboxRequest {
sandbox_id: "test".to_string(),
command: vec!["ls".to_string()],
workdir: "/tmp\nmalicious".to_string(),
..Default::default()
};
let err = validate_exec_request_fields(&req).unwrap_err();
assert!(err.message().contains("newline"));
}

#[test]
fn validate_exec_still_rejects_newlines_in_env_values() {
let req = ExecSandboxRequest {
sandbox_id: "test".to_string(),
command: vec!["ls".to_string()],
environment: std::iter::once(("VAR".to_string(), "val\nmalicious".to_string()))
.collect(),
..Default::default()
};
let err = validate_exec_request_fields(&req).unwrap_err();
assert!(err.message().contains("newline"));
}
}
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