Google Native Client
- Not to be confused with Networking and Cryptography library.
SDK: Pepper 43 (3 April 2015 ), Client:
|Development status||Production (NaCl, PNaCl)|
|Written in||C, C++|
|Operating system||Cross-platform: Microsoft Windows, Linux, OS X, Chrome OS|
|Platform||x86, x64, ARM, MIPS|
|Type||Sandbox in web browsers for native code|
|License||New BSD license|
Google Native Client (NaCl) is a sandboxing technology for running a subset of Intel x86/x64, ARM or MIPS native code in a sandbox. It allows safely running native code from a web browser, independent of the user operating system, allowing web-based applications to run at near-native speeds, which aligns with Google's plans for Chrome OS. It may also be used for securing browser plugins, as well as parts of other applications or full applications such as ZeroVM.
To demonstrate the readiness of the technology, on 9 December 2011, Google announced the availability of several new Chrome-only versions of games known for their rich and processor-intensive graphics, including Bastion (Bastion is no longer supported on the Chrome Web Store). NaCl runs hardware-accelerated 3D graphics (via OpenGL ES 2.0), sandboxed local file storage, dynamic loading, full screen mode, and mouse capture. There are also plans to make NaCl available on handheld devices.
The general concept of NaCl (running native code in web browser) has been implemented before in ActiveX, which, while still in use, has a legacy of DLL hell and security problems. Native Client avoids these issues by using sandboxing. Using PNaCl, Native Client is also architecture-independent, like Java. Unlike Java, PNaCl apps are compiled ahead-of-time in the browser, and not just-in-time. This can make performance more predictable.
Native Client is an open-source project being developed by Google. To date, Quake, XaoS, Battle for Wesnoth, Doom, Lara Croft and the Guardian of Light and MAME, as well as the sound processing system Csound, have been ported to Native Client. Native Client has been available in the Google Chrome web browser since version 14, and has been enabled by default since version 31, when Portable Native Client (PNaCl, pronounced: pinnacle) was released.
To run an application portably under PNaCl, it must be compiled to an architecture-agnostic and stable subset of the LLVM intermediate representation bytecode. The executables are called PNaCl executables (pexes). In Chrome, they are translated to architecture-specific executables so that they can be run.
NaCl uses software fault isolation for sandboxing on x86-64 and ARM. The x86-32 implementation of Native Client is notable for its novel sandboxing method which makes use of the x86 architecture's rarely used segmentation facility. Native Client sets up x86 segments to restrict the memory range that the sandboxed code can access. It uses a code verifier to prevent use of unsafe instructions such as those that perform system calls. To prevent the code from jumping to an unsafe instruction hidden in the middle of a safe instruction, Native Client requires that all indirect jumps be jumps to the start of 32-byte-aligned blocks, and instructions are not allowed to straddle these blocks. Because of these constraints, C/C++ code must be recompiled to run under Native Client, which provides customized versions of the GNU toolchain, specifically GCC and binutils as well as LLVM.
Native Client is licensed under a BSD-style license.
NaCl denotes table salt; as a pun, the name of pepper was also used. Pepper API is a cross-platform, open-source API for creating Native Client modules. Pepper Plugin API, or PPAPI is a cross-platform API for Native Client-secured web browser plugins, first based on Netscape's NPAPI, then rewritten from scratch. It is currently used in Chromium and Google Chrome to enable the PPAPI version of Flash and the built-in PDF viewer.
On 12 August 2009 a page on Google Code introduced a new project, Pepper with associated Pepper Plugin API (PPAPI), "a set of modifications to NPAPI to make plugins more portable and more secure". This extension is designed specifically to ease the implementation of out-of-process plugin execution. Further, the goals of the project are to provide a framework for making plugins fully cross-platform. Topics considered include:
- Uniform semantics for NPAPI across browsers.
- Execution in a separate process from the renderer/browser itself.
- Standardize rendering using the browser's compositing process.
- Defining standardized events, and 2D rasterization functions.
- Initial attempt at providing 3D graphics access.
- Plugin registry.
As of 13 May 2010[update], Google's open source browser, Chromium, was the only web browser to utilize the new browser plug-in model. Mozilla has announced that they are "not interested in or working on Pepper at this time." As of 2015, Pepper is supported by Chrome, Chromium and Opera.
Some groups of browser developers support the Native Client technology, but others do not.
Id Software's John Carmack praised Native Client at QuakeCon 2012, saying: "if you have to do something inside a browser, Native Client is much more interesting as something that started out as a really pretty darn clever x86 hack in the way that they could sandbox all of this in user mode interestingly. It's now dynamic recompilation, but something that you program in C or C++ and it compiles down to something that's going to be not your -O4 optimization level for completely native code but pretty damn close to native code. You could do all of your evil pointer chasings, and whatever you want to do as a to-the-metal game developer."
Detractors: Other IT professionals are more critical of this sandboxing technology as it has substantial or substantive interoperability issues.
Mozilla's vice president of products, Jay Sullivan, said that Mozilla has no intention of running native code inside the browser, as "These native apps are just little black boxes in a webpage. [...] We really believe in HTML, and this is where we want to focus."
Mozilla's Christopher Blizzard criticized NaCl, claiming that native code cannot evolve in the same way that the source code-driven web can. He also compared NaCl to Microsoft's ActiveX technology, plagued with DLL hell.
Håkon Wium Lie, Opera's CTO, believes that "NaCl seems to be 'yearning for the bad old days, before the web'", and that "Native Client is about building a new platform – or porting an old platform into the web [...] it will bring in complexity and security issues, and it will take away focus from the web platform."
- "Stable Channel Update". Chrome Releases. Blogger. July 28, 2015. Retrieved July 28, 2015.
- Chrome Revision 213999
- Cade Metz (12 September 2011). "Google Native Client: The web of the future – or the past?". The Register. Retrieved 17 September 2011.
- "ZeroVM Architecture". Retrieved 16 March 2014.
- Seth Rosenblatt (9 December 2011). "Native Client turns Chrome into high-end gaming platform". CNET. Retrieved 9 December 2011.
- "Google Code Blog: Games, apps and runtimes come to Native Client". Googlecode.blogspot.com. 9 December 2011. Retrieved 25 April 2012.
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- "PNaCl: Portable Native Client Executables" (PDF). Retrieved 25 April 2012.
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- Bennet Yee, David Sehr, Greg Dardyk, Brad Chen, Robert Muth, Tavis Ormandy, Shiki Okasaka, Neha Narula, Nicholas Fullagar (2009). "Native Client: A Sandbox for Portable, Untrusted x86 Native Code". IEEE Symposium on Security and Privacy (Oakland'09). Retrieved 31 July 2011.
- "Native Client: Building". developer.chrome.com. Retrieved 16 March 2014.
- Native Client: Technical Overview
- "Pepper Plugin API project at". Google. Retrieved 25 April 2012.
- "Chrome Source: Index of /trunk/src/ppapi". Src.chromium.org. Retrieved 25 April 2012.
- "The road to safer, more stable, and flashier Flash". Google. 8 August 2012. Retrieved 10 August 2013.
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- Comment by t.hajdu....@gmail.com (24 February 2012). "Pepper.wiki". Google. Retrieved 25 April 2012.
- Native Client: News & Announcements
- Metz, Cade (13 May 2010). "Google heats up native code for Chrome OS". Theregister.co.uk. Retrieved 25 April 2012.
- "NPAPI:Pepper – MozillaWiki". Wiki.mozilla.org. 26 May 2011. Retrieved 25 April 2012.
- Austin, Chad (8 January 2011). "Chad Austin: In Defense of Language Democracy (Or: Why the Browser Needs a Virtual Machine)". Chadaustin.me. Retrieved 25 April 2012.
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- Metz, Cade (24 June 2010). "Mozilla: Our browser will not run native code". The Register. Retrieved 25 April 2012.
- Native Client - Google Developers (Native Client Developer Site)
- Google Native Client Project Page
- Google I/O 2013 - Introduction to Portable Native Client (PNaCl) on YouTube
- Google I/O 2009 Native Code for Compute Intensive Web Apps on YouTube – Technical talk at Google I/O 2009
- A list of OSS projects ported to Native Client
- Native Client source code in Git
- PNaCl examples (runs in Chrome 31+, PNaCl, i.e. no installation needed)
- Native Client SDK Gallery
- torapp.info, vector editor, especially powerful for security printing (not PNaCl)
- NACLBox, a port of DOSBox to Native Client (PNaCl)
- SodaSynth, a synthesizer for Native Client (not PNaCl)
- pnacl-amiga-emulator, a port of UAE, an Amiga 500 emulator