About

This is a prototype for plumbing Mojo into the NaCl sandbox. It is currently insecure (see below), and does not support Mojo functions that return pointers (for example, MojoMapBuffer).

Currently, SFI NaCl support is not being actively developed, in favor of non-SFI NaCl support.

Using

The SFI NaCl and accompanying tests should be built by default for Linux. The boolean indicating if they are built is “mojo_use_nacl”, defined inside the BUILD files.

This should create a “monacl_shell” executable, capable of running standalone SFI nexes.

Additionally, it will create a content handler for SFI nexes -- any Nexe with the line “#!mojo mojo:nacl_content_handler” prepended to it will be redirected to the SFI content handler when run with the “mojo_shell”.

Notes

nacl_bindings_generator/interface.py contains a programmatic description of the stable Mojo interface. This will need to be updated as the interface changes. Run nacl_bindings_generator/generate_nacl_bindings.py to generate the bindings that plumb this interface into the NaCl sandbox.

Security TODO

• Validate and copy option structures.
• Protect untrusted buffers passed into Mojo:
  • NaClVmIoWillStart/HasEnded.
  • volatile accesses to untrusted memory (untrusted code could race).
• Overflow checking in array bounds validation.