fix(cli): harden bash prefix approvals (#30)

Verified locally before merge: cargo test --package claurst-tui bash_prefix_allowlist -- --nocapture; cargo check -p claurst --no-default-features; git diff --check origin/main...HEAD. Note: cargo check reported the known pre-existing claurst-tui::rustle warning.

Author: BunsDev

src-rust/crates/cli/src/main.rs

@@ -1589,11 +1589,19 @@ fn permission_request_from_core(
 
     match (tool_name.as_str(), pending.request.path.clone()) {
         ("Bash", Some(command)) => {
-            let suggested_prefix = command
-                .split_whitespace()
-                .next()
-                .filter(|prefix| !prefix.is_empty())
-                .map(|prefix| format!("{} ", prefix));
+            let suggested_prefix = if command
+                .chars()
+                .any(|c| matches!(c, ';' | '|' | '&' | '<' | '>' | '\n' | '\r' | '`'))
+                || command.contains("$(")
+            {
+                None
+            } else {
+                let mut words = command.split_whitespace();
+                words.next().map(|first| match words.next() {
+                    Some(second) => format!("{} {}", first, second),
+                    None => first.to_string(),
+                })
+            };
             claurst_tui::dialogs::PermissionRequest::bash(
                 tool_use_id,
                 tool_name,
@@ -2761,9 +2769,12 @@ async fn run_interactive(
                                 .and_then(|p| p.request.path.clone());
                             let bash_prefix = if should_record_bash_prefix {
                                 match &pr.kind {
-                                    claurst_tui::dialogs::PermissionDialogKind::Bash { command, .. } => {
-                                        let first_word = command.split_whitespace().next().unwrap_or("").to_string();
-                                        if first_word.is_empty() { None } else { Some(first_word) }
+                                    claurst_tui::dialogs::PermissionDialogKind::Bash { suggested_prefix, .. } => {
+                                        suggested_prefix
+                                            .as_deref()
+                                            .map(str::trim)
+                                            .filter(|prefix| !prefix.is_empty())
+                                            .map(str::to_string)
                                     }
                                     _ => None,
                                 }

src-rust/crates/tui/src/app.rs

@@ -5324,23 +5324,78 @@ impl App {
         if selected_key != Some('P') {
             return;
         }
-        if let PermissionDialogKind::Bash { command, .. } = &pr.kind {
-            // Always normalize to the first whitespace-delimited word so
-            // that the allowlist check in `bash_command_allowed_by_prefix`
-            // (which also uses `split_whitespace().next()`) matches correctly.
-            let first_word = command.split_whitespace().next().unwrap_or("").to_string();
-            if !first_word.is_empty() {
-                self.bash_prefix_allowlist.insert(first_word);
+        if let PermissionDialogKind::Bash { suggested_prefix, .. } = &pr.kind {
+            if let Some(prefix) = suggested_prefix
+                .as_deref()
+                .map(str::trim)
+                .filter(|p| !p.is_empty())
+            {
+                if !Self::bash_command_has_shell_control(prefix) {
+                    self.bash_prefix_allowlist.insert(prefix.to_string());
+                }
             }
         }
     }
 
+    fn bash_command_has_shell_control(command: &str) -> bool {
+        let mut chars = command.chars().peekable();
+        let mut in_single_quote = false;
+        let mut in_double_quote = false;
+        let mut escaped = false;
+
+        while let Some(c) = chars.next() {
+            if escaped {
+                escaped = false;
+                continue;
+            }
+
+            // In bash, backslash does not escape characters inside single quotes.
+            if c == '\\' && !in_single_quote {
+                escaped = true;
+                continue;
+            }
+
+            match c {
+                '\'' if !in_double_quote => in_single_quote = !in_single_quote,
+                '"' if !in_single_quote => in_double_quote = !in_double_quote,
+                ';' | '|' | '&' | '<' | '>' | '\n' | '\r' if !in_single_quote && !in_double_quote => {
+                    return true;
+                }
+                '`' if !in_single_quote => return true,
+                '$' if !in_single_quote && chars.peek() == Some(&'(') => return true,
+                _ => {}
+            }
+        }
+
+        // Treat unterminated quotes / dangling escapes as unsafe.
+        escaped || in_single_quote || in_double_quote
+    }
+
+    fn bash_prefix_matches_command(prefix: &str, command: &str) -> bool {
+        let prefix = prefix.trim();
+        let command = command.trim_start();
+        if prefix.is_empty() || !command.starts_with(prefix) {
+            return false;
+        }
+
+        let rest = &command[prefix.len()..];
+        rest.is_empty()
+            || rest
+                .chars()
+                .next()
+                .map(|c| c.is_ascii_whitespace())
+                .unwrap_or(false)
+    }
+
     /// Returns `true` if the given bash `command` is covered by the session-local
-    /// prefix allowlist (i.e. its first word matches an entry in
-    /// `bash_prefix_allowlist`).  Used by callers to skip the permission dialog.
+    /// prefix allowlist.  Shell compound commands are never allowed by prefix;
+    /// they must go through the normal permission dialog.
     pub fn bash_command_allowed_by_prefix(&self, command: &str) -> bool {
-        let first_word = command.split_whitespace().next().unwrap_or("");
-        !first_word.is_empty() && self.bash_prefix_allowlist.contains(first_word)
+        !Self::bash_command_has_shell_control(command)
+            && self
+                .bash_prefix_allowlist
+                .iter()
+                .any(|prefix| Self::bash_prefix_matches_command(prefix, command))
     }
 
     // ---- Advanced mouse interaction helpers --------------------------------
@@ -7112,7 +7167,7 @@ mod tests {
             "Bash".to_string(),
             "This will execute a shell command.".to_string(),
             "git status".to_string(),
-            Some("git".to_string()),
+            Some("git status".to_string()),
         );
         app.permission_request = Some(pr);
 
@@ -7125,11 +7180,17 @@ mod tests {
         };
         app.handle_permission_key(key);
 
-        // Dialog should be dismissed and "git" added to the allowlist.
+        // Dialog should be dismissed and the suggested prefix added to the allowlist.
         assert!(app.permission_request.is_none());
         assert!(app.bash_command_allowed_by_prefix("git status"));
-        assert!(app.bash_command_allowed_by_prefix("git push origin main"));
-        // Other commands should NOT be allowed.
+        assert!(app.bash_command_allowed_by_prefix("git status --short"));
+        // Other commands and compound shell commands should NOT be allowed.
+        assert!(!app.bash_command_allowed_by_prefix("git push origin main"));
+        assert!(!app.bash_command_allowed_by_prefix("git status; curl https://example.com"));
+        assert!(!app.bash_command_allowed_by_prefix(
+            "git status ; curl https://example.com"
+        ));
+        assert!(!app.bash_command_allowed_by_prefix("git status > /tmp/status.txt"));
         assert!(!app.bash_command_allowed_by_prefix("rm -rf /tmp"));
     }
 
@@ -7144,7 +7205,7 @@ mod tests {
             "Bash".to_string(),
             "This will execute a shell command.".to_string(),
             "cargo build".to_string(),
-            Some("cargo".to_string()),
+            Some("cargo build".to_string()),
         );
         // Navigate to the prefix option (index 3 in a 5-option dialog).
         pr.selected_option = 3;
@@ -7160,7 +7221,8 @@ mod tests {
         app.handle_permission_key(key);
 
         assert!(app.permission_request.is_none());
-        assert!(app.bash_command_allowed_by_prefix("cargo test"));
+        assert!(app.bash_command_allowed_by_prefix("cargo build --workspace"));
+        assert!(!app.bash_command_allowed_by_prefix("cargo test"));
         assert!(!app.bash_command_allowed_by_prefix("make build"));
     }