[Aikido] Validate gpg.program paths to prevent arbitrary code execution

src-tauri/src/commands/history.rs

@@ -350,7 +350,9 @@ fn effective_gpg_program(
     runner: &impl VerificationRunner,
 ) -> Result<String, String> {
     if let Ok(Some(program)) = runner.git_config_get(repo_path, "gpg.program") {
-        return Ok(program);
+        if let Some(validated) = validate_gpg_program_from_repo(&program) {
+            return Ok(validated);
+        }
     }
 
     #[cfg(windows)]
@@ -363,6 +365,52 @@ fn effective_gpg_program(
     Ok("gpg".to_string())
 }
 
+/// Accepts programs resolved from `PATH` and existing absolute files.
+fn validate_gpg_program_from_repo(program: &str) -> Option<String> {
+    let trimmed = program.trim().trim_matches('"');
+
+    if trimmed.is_empty() {
+        return None;
+    }
+
+    let is_path_like =
+        Path::new(trimmed).is_absolute() || trimmed.contains('/') || trimmed.contains('\\');
+
+    if is_path_like {
+        let path = Path::new(trimmed);
+        if path.is_absolute() && path.is_file() {
+            return Some(trimmed.to_string());
+        }
+        return None;
+    }
+
+    #[cfg(windows)]
+    let exists = {
+        let executable_name = format!("{trimmed}.exe");
+        program_exists_on_path(&[executable_name.as_str(), trimmed])
+    };
+    #[cfg(not(windows))]
+    let exists = program_exists_on_path(&[trimmed]);
+
+    exists.then(|| trimmed.to_string())
+}
+
+fn program_exists_on_path(names: &[&str]) -> bool {
+    let Some(path_var) = std::env::var_os("PATH") else {
+        return false;
+    };
+
+    for dir in std::env::split_paths(&path_var) {
+        for name in names {
+            let candidate = dir.join(name);
+            if candidate.exists() && candidate.is_file() {
+                return true;
+            }
+        }
+    }
+    false
+}
+
 fn signature_key_type(commit_text: &str) -> Option<String> {
     if commit_text.contains("-----BEGIN SSH SIGNATURE-----") {
         return Some("ssh".to_string());
@@ -524,14 +572,14 @@ mod tests {
             "a\x1fG\x1fAlice\x1fABC123\x1fABC123",
         ])
         .with_key_type("a", "gpg")
-        .with_gpg_program("/usr/local/bin/gpg");
+        .with_gpg_program("gpg");
         let results = verify_commit_signatures("/repo", &["a".to_string()], true, &runner)
             .expect("verification should complete");
 
         assert_eq!(results[0].status, SignatureStatus::Verified);
         assert_eq!(
             runner.fetched_keys.borrow().as_slice(),
-            &["/usr/local/bin/gpg ABC123".to_string()]
+            &["gpg ABC123".to_string()]
         );
         assert_eq!(
             runner.verified_hashes.borrow().as_slice(),
@@ -599,6 +647,48 @@ mod tests {
 
         assert_eq!(error, "fatal: bad revision");
     }
+
+    #[test]
+    fn validate_gpg_program_rejects_empty_string() {
+        assert_eq!(validate_gpg_program_from_repo(""), None);
+    }
+
+    #[test]
+    fn validate_gpg_program_rejects_relative_paths() {
+        assert_eq!(validate_gpg_program_from_repo("./malicious/gpg"), None);
+    }
+
+    #[test]
+    fn validate_gpg_program_rejects_relative_paths_with_backslash() {
+        assert_eq!(validate_gpg_program_from_repo(".\\malicious\\gpg"), None);
+    }
+
+    #[test]
+    fn validate_gpg_program_rejects_nonexistent_absolute_paths() {
+        assert_eq!(
+            validate_gpg_program_from_repo("/nonexistent/path/to/gpg"),
+            None
+        );
+    }
+
+    #[test]
+    fn validate_gpg_program_rejects_nonexistent_program_names() {
+        assert_eq!(
+            validate_gpg_program_from_repo("nonexistent_gpg_program_12345"),
+            None
+        );
+    }
+
+    #[test]
+    fn validate_gpg_program_accepts_existing_absolute_file() {
+        let executable = std::env::current_exe().expect("current test executable");
+        let executable = executable.to_str().expect("UTF-8 executable path");
+
+        assert_eq!(
+            validate_gpg_program_from_repo(executable),
+            Some(executable.to_string())
+        );
+    }
 }
 
 #[tauri::command]