Where do the program write info to the fifo?

shiwanghua · November 29, 2024, 2:20pm

Create the fifo at L101:

fkie-cad/cwe_checker/blob/37c8125d02fbfa8c68e24c89f257280258b0b536/src/cwe_checker_lib/src/utils/ghidra.rs#L101


      
          /// Execute Ghidra with the P-Code plugin and return the parsed P-Code project.
          ///
          /// Note that this function will abort the program is the Ghidra execution does not succeed.
          fn execute_ghidra(
              mut ghidra_command: Command,
              fifo_path: &PathBuf,
              debug_settings: &debug::Settings,
          ) -> Result<crate::pcode::Project, Error> {
              let should_print_ghidra_error = debug_settings.verbose();
              // Create a new fifo and give read and write rights to the owner
              unistd::mkfifo(fifo_path, stat::Mode::from_bits(0o600).unwrap())
                  .context("Error creating FIFO pipe")?;
              // Execute Ghidra in a new thread and return a Join Handle, so that the thread is only joined
              // after the output has been read into the cwe_checker
              let ghidra_subprocess = thread::spawn(move || {
                  // Execute the command and catch its output.
                  let output = match ghidra_command.output() {
                      Ok(output) => output,
                      Err(err) => {
                          eprintln!("Ghidra could not be executed: {err}");
                          std::process::exit(101);

then directly open and read from the fifo file:

github.com

fkie-cad/cwe_checker/blob/37c8125d02fbfa8c68e24c89f257280258b0b536/src/cwe_checker_lib/src/utils/ghidra.rs#L134


      
                      eprintln!("Ghidra plugin failed with exit code {code}");
                  }
                  eprintln!("Execution of Ghidra plugin failed.");
              } else {
                  eprintln!("Execution of Ghidra plugin failed. Use the --verbose flag to print Ghidra output for troubleshooting.");
              }
              std::process::exit(101)
          });
          
          // Open the FIFO
          let mut file = std::fs::File::open(fifo_path.clone()).expect("Could not open FIFO.");
          let mut buf = String::new();
          file.read_to_string(&mut buf)
              .expect("Error while reading from FIFO.");
          debug_settings.print(&buf, debug::Stage::Pcode(debug::PcodeForm::Raw));
          let pcode_parsing_result = serde_json::from_str(&buf);
          
          ghidra_subprocess
              .join()
              .expect("The Ghidra thread to be joined has panicked!");
          // Clean up the FIFO pipe and propagate errors from the JSON parsing.

file->buf->pcode_parsing_result

and finally return the pcode_parsing_result

but the ghidra_command.output() is not put into the fifo file,

how does it work ?

jer · November 29, 2024, 2:49pm

The same fifo_path is passed as an argument to the invoked program:

github.com

fkie-cad/cwe_checker/blob/37c8125d02fbfa8c68e24c89f257280258b0b536/src/cwe_checker_lib/src/utils/ghidra.rs#L47-L52


      
          let ghidra_command = generate_ghidra_call_command(
              file_path,
              &fifo_path,
              &timestamp_suffix,
              &bare_metal_config_opt,
          )?;

github.com

fkie-cad/cwe_checker/blob/37c8125d02fbfa8c68e24c89f257280258b0b536/src/cwe_checker_lib/src/utils/ghidra.rs#L169-L176


      
          ghidra_command
              .arg(&tmp_folder) // The folder where temporary files should be stored
              .arg(format!("PcodeExtractor_{filename}_{timestamp_suffix}")) // The name of the temporary Ghidra Project.
              .arg("-import") // Import a file into the Ghidra project
              .arg(file_path) // File import path
              .arg("-postScript") // Execute a script after standard analysis by Ghidra finished
              .arg(ghidra_plugin_path.join("PcodeExtractor.java")) // Path to the PcodeExtractor.java
              .arg(fifo_path) // The path to the named pipe (fifo)

So ghidra will just open that path and write into it.

shiwanghua · December 2, 2024, 1:29pm

Yes, I also found the generate_ghidra_call_command function just now after looking at the code for a few minutes

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Where do the program write info to the fifo?

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