diff options
author | Mike Pall <mike> | 2020-07-12 15:09:55 +0200 |
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committer | Mike Pall <mike> | 2020-07-12 15:09:55 +0200 |
commit | 7eb96843ff9d4bed019e8cd7c17727557e39e89c (patch) | |
tree | 14b220ce0928164a8c25e79c205fb61369bbc98b /doc | |
parent | 53f82e6e2e858a0a62fd1a2ff47e9866693382e6 (diff) | |
download | luajit2-7eb96843ff9d4bed019e8cd7c17727557e39e89c.tar.gz |
Add FAQ about sandboxing. Minor fixes.
Diffstat (limited to 'doc')
-rw-r--r-- | doc/extensions.html | 2 | ||||
-rw-r--r-- | doc/faq.html | 40 |
2 files changed, 33 insertions, 9 deletions
diff --git a/doc/extensions.html b/doc/extensions.html index b36e2855..0fc65330 100644 --- a/doc/extensions.html +++ b/doc/extensions.html @@ -326,7 +326,7 @@ the toolchain used to compile LuaJIT: </tr> <tr class="odd"> <td class="excplatform">Windows/x64</td> -<td class="exccompiler">MSVC or WinSDK</td> +<td class="exccompiler">MSVC</td> <td class="excinterop"><b style="color: #00a000;">Full</b></td> </tr> <tr class="even"> diff --git a/doc/faq.html b/doc/faq.html index 6208882b..65b0d842 100644 --- a/doc/faq.html +++ b/doc/faq.html @@ -55,7 +55,7 @@ dd { margin-left: 1.5em; } </li></ul> </div> <div id="main"> -<dl> +<dl id="info"> <dt>Q: Where can I learn more about LuaJIT and Lua?</dt> <dd> <ul style="padding: 0;"> @@ -75,7 +75,7 @@ has information about diverse topics.</li> </ul> </dl> -<dl> +<dl id="tech"> <dt>Q: Where can I learn more about the compiler technology used by LuaJIT?</dt> <dd> I'm planning to write more documentation about the internals of LuaJIT. @@ -91,7 +91,7 @@ And, you know, reading the source is of course the only way to enlightenment. :- </dd> </dl> -<dl> +<dl id="arg"> <dt>Q: Why do I get this error: "attempt to index global 'arg' (a nil value)"?<br> Q: My vararg functions fail after switching to LuaJIT!</dt> <dd>LuaJIT is compatible to the Lua 5.1 language standard. It doesn't @@ -101,7 +101,7 @@ functions from Lua 5.0.<br>Please convert your code to the vararg syntax</a>.</dd> </dl> -<dl> +<dl id="x87"> <dt>Q: Why do I get this error: "bad FPU precision"?<br> <dt>Q: I get weird behavior after initializing Direct3D.<br> <dt>Q: Some FPU operations crash after I load a Delphi DLL.<br> @@ -123,7 +123,7 @@ Please check the Delphi docs for the Set8087CW method. </dl> -<dl> +<dl id="ctrlc"> <dt>Q: Sometimes Ctrl-C fails to stop my Lua program. Why?</dt> <dd>The interrupt signal handler sets a Lua debug hook. But this is currently ignored by compiled code (this will eventually be fixed). If @@ -134,7 +134,31 @@ twice to get stop your program. That's similar to when it's stuck running inside a C function under the Lua interpreter.</dd> </dl> -<dl> +<dl id="sandbox"> +<dt>Q: Can Lua code be safely sandboxed?</dt> +<dd> +Maybe for an extremly restricted subset of Lua and if you relentlessly +scrutinize every single interface function you offer to the untrusted code.<br> + +Although Lua provides some sandboxing functionality (<tt>setfenv()</tt>, hooks), +it's very hard to get this right even for the Lua core libraries. Of course, +you'll need to inspect any extension library, too. And there are libraries +that are inherently unsafe, e.g. the <a href="ext_ffi.html">FFI library</a>.<br> + +Relatedly, <b>loading untrusted bytecode is not safe!</b> It's trivial +to crash the Lua or LuaJIT VM with maliciously crafted bytecode. This is +well known and there's no bytecode verification on purpose, so please +don't report a bug about it. Check the <tt>mode</tt> parameter for the +<tt>load*()</tt> functions to disable loading of bytecode.<br> + +In general, the only promising approach is to sandbox Lua code at the +process level and not the VM level.<br> + +More reading material at the <a href="http://lua-users.org/wiki/SandBoxes"><span class="ext">»</span> Lua Wiki</a> and <a href="https://en.wikipedia.org/wiki/Sandbox_(computer_security)">Wikipedia</a>. +</dd> +</dl> + +<dl id="patches"> <dt>Q: Why doesn't my favorite power-patch for Lua apply against LuaJIT?</dt> <dd>Because it's a completely redesigned VM and has very little code in common with Lua anymore. Also, if the patch introduces changes to @@ -145,7 +169,7 @@ can use source transformations or use wrapper or proxy functions. The compiler will happily optimize away such indirections.</dd> </dl> -<dl> +<dl id="arch"> <dt>Q: Lua runs everywhere. Why doesn't LuaJIT support my CPU?</dt> <dd>Because it's a compiler — it needs to generate native machine code. This means the code generator must be ported to each @@ -156,7 +180,7 @@ architectures. Other architectures will follow based on sufficient user demand and/or sponsoring.</dd> </dl> -<dl> +<dl id="when"> <dt>Q: When will feature X be added? When will the next version be released?</dt> <dd>When it's ready.<br> C'mon, it's open source — I'm doing it on my own time and you're |