assay/lua/
mod.rs

1pub mod async_bridge;
2pub mod builtins;
3
4use anyhow::Result;
5use include_dir::{Dir, include_dir};
6use mlua::{Lua, LuaOptions, StdLib};
7
8static STDLIB_DIR: Dir = include_dir!("$CARGO_MANIFEST_DIR/stdlib");
9
10/// Environment variable to override the global module search path.
11pub const MODULES_PATH_ENV: &str = "ASSAY_MODULES_PATH";
12
13/// Comma-separated list of additional globals to nil out at VM
14/// creation time (defense-in-depth knob for hardened deployments).
15/// Names support dotted paths into stdlib tables — e.g.
16/// `ASSAY_BLOCK_GLOBALS=dofile,os.execute,debug.getinfo`.
17pub const BLOCK_GLOBALS_ENV: &str = "ASSAY_BLOCK_GLOBALS";
18
19fn lua_err(e: mlua::Error) -> anyhow::Error {
20    anyhow::anyhow!("{e}")
21}
22
23pub fn create_vm(client: reqwest::Client) -> Result<Lua> {
24    create_vm_with_paths(client, None)
25}
26
27#[allow(dead_code)]
28pub fn create_vm_with_lib_path(client: reqwest::Client, lib_path: String) -> Result<Lua> {
29    create_vm_with_paths(client, Some(lib_path))
30}
31
32pub fn create_vm_with_paths(
33    client: reqwest::Client,
34    global_modules_path: Option<String>,
35) -> Result<Lua> {
36    let libs = StdLib::ALL_SAFE;
37    let lua = Lua::new_with(libs, LuaOptions::default()).map_err(lua_err)?;
38    lua.set_memory_limit(64 * 1024 * 1024).map_err(lua_err)?;
39    sandbox(&lua).map_err(lua_err)?;
40    register_fs_loader(&lua, global_modules_path).map_err(lua_err)?;
41    register_stdlib_loader(&lua).map_err(lua_err)?;
42    builtins::register_all(&lua, client).map_err(lua_err)?;
43    Ok(lua)
44}
45
46fn sandbox(lua: &Lua) -> mlua::Result<()> {
47    // Block bytecode-level escape hatches only. Source-level loaders
48    // (`load` / `loadfile` / `dofile`) stay available — operator scripts
49    // are trusted to compose themselves out of multiple files (seed +
50    // init bootstraps, shared helpers, etc.). `string.dump` stays
51    // blocked because it produces native bytecode that defeats the
52    // memory/CPU caps the runtime relies on.
53    let globals = lua.globals();
54    let string_lib: mlua::Table = globals.get("string")?;
55    string_lib.set("dump", mlua::Value::Nil)?;
56
57    if let Ok(extra) = std::env::var(BLOCK_GLOBALS_ENV) {
58        for raw in extra.split(',') {
59            let name = raw.trim();
60            if name.is_empty() {
61                continue;
62            }
63            nil_dotted_path(lua, name)?;
64        }
65    }
66
67    Ok(())
68}
69
70/// Resolve a dotted Lua path (e.g. `"os.execute"` or `"debug.getinfo"`)
71/// against globals and set the leaf to nil. A bare name (e.g.
72/// `"dofile"`) clears it from `_G`. Missing intermediate tables are
73/// silently skipped so a typo in `ASSAY_BLOCK_GLOBALS` doesn't fail
74/// VM creation.
75fn nil_dotted_path(lua: &Lua, path: &str) -> mlua::Result<()> {
76    let parts: Vec<&str> = path.split('.').filter(|s| !s.is_empty()).collect();
77    if parts.is_empty() {
78        return Ok(());
79    }
80    let mut current: mlua::Table = lua.globals();
81    for segment in &parts[..parts.len() - 1] {
82        let next: mlua::Value = current.get(*segment)?;
83        match next {
84            mlua::Value::Table(t) => current = t,
85            _ => return Ok(()),
86        }
87    }
88    current.set(parts[parts.len() - 1], mlua::Value::Nil)
89}
90
91fn register_stdlib_loader(lua: &Lua) -> mlua::Result<()> {
92    let package: mlua::Table = lua.globals().get("package")?;
93    let searchers: mlua::Table = package.get("searchers")?;
94
95    // Resolves `require("assay.ory.kratos")` -> "ory/kratos.lua" by replacing
96    // dots with slashes, matching standard Lua package loading convention.
97    // Tries "<path>.lua" first, then falls back to "<path>/init.lua" so
98    // both `stdlib/ory.lua` (flat convenience wrapper) and
99    // `stdlib/ory/kratos.lua` (nested submodule) resolve correctly.
100    let stdlib_searcher = lua.create_function(|lua, module_name: String| {
101        let rest = match module_name.strip_prefix("assay.") {
102            Some(r) => r,
103            None => {
104                return Ok(mlua::Value::String(
105                    lua.create_string(format!("not an assay.* module: {module_name}"))?,
106                ));
107            }
108        };
109
110        let base = rest.replace('.', "/");
111        let candidates = [format!("{base}.lua"), format!("{base}/init.lua")];
112
113        for path in &candidates {
114            if let Some(file) = STDLIB_DIR.get_file(path) {
115                let source = file.contents_utf8().ok_or_else(|| {
116                    mlua::Error::runtime(format!("stdlib {path}: invalid UTF-8"))
117                })?;
118                let loader = lua
119                    .load(source)
120                    .set_name(format!("@assay/{path}"))
121                    .into_function()?;
122                return Ok(mlua::Value::Function(loader));
123            }
124        }
125
126        Ok(mlua::Value::String(
127            lua.create_string(format!("no embedded stdlib file: {}", candidates[0]))?,
128        ))
129    })?;
130
131    let len = searchers.len()?;
132    searchers.set(len + 1, stdlib_searcher)?;
133
134    Ok(())
135}
136
137fn register_fs_loader(lua: &Lua, global_modules_path: Option<String>) -> mlua::Result<()> {
138    let package: mlua::Table = lua.globals().get("package")?;
139    let searchers: mlua::Table = package.get("searchers")?;
140
141    // Same dotted-path resolution as the stdlib loader: `assay.ory.kratos`
142    // -> "ory/kratos.lua", falling back to "ory/kratos/init.lua".
143    let fs_searcher = lua.create_function(move |lua, module_name: String| {
144        let rest = match module_name.strip_prefix("assay.") {
145            Some(r) => r,
146            None => {
147                return Ok(mlua::Value::String(
148                    lua.create_string(format!("not an assay.* module: {module_name}"))?,
149                ));
150            }
151        };
152        let base = rest.replace('.', "/");
153        let candidates = [format!("{base}.lua"), format!("{base}/init.lua")];
154
155        let try_load = |dir: &std::path::Path| -> Option<(std::path::PathBuf, String)> {
156            for rel in &candidates {
157                let full = dir.join(rel);
158                if let Ok(source) = std::fs::read_to_string(&full) {
159                    return Some((full, source));
160                }
161            }
162            None
163        };
164
165        // Priority 1: ./modules/<path>.lua (per-project)
166        if let Some((full, source)) = try_load(std::path::Path::new("./modules")) {
167            let loader = lua
168                .load(source)
169                .set_name(format!("@{}", full.display()))
170                .into_function()?;
171            return Ok(mlua::Value::Function(loader));
172        }
173
174        // Priority 2: $ASSAY_MODULES_PATH or ~/.assay/modules/<path>.lua
175        let global_path = if let Some(ref custom_path) = global_modules_path {
176            std::path::PathBuf::from(custom_path)
177        } else if let Ok(modules_env) = std::env::var(MODULES_PATH_ENV) {
178            std::path::PathBuf::from(modules_env)
179        } else if let Ok(home) = std::env::var("HOME") {
180            std::path::Path::new(&home).join(".assay/modules")
181        } else {
182            std::path::PathBuf::new()
183        };
184
185        if !global_path.as_os_str().is_empty()
186            && let Some((full, source)) = try_load(&global_path)
187        {
188            let loader = lua
189                .load(source)
190                .set_name(format!("@{}", full.display()))
191                .into_function()?;
192            return Ok(mlua::Value::Function(loader));
193        }
194
195        // Priority 3: Built-in modules are handled by register_stdlib_loader
196        // Return nil to fall through to the next searcher
197        Ok(mlua::Value::Nil)
198    })?;
199
200    let len = searchers.len()?;
201    searchers.set(len + 1, fs_searcher)?;
202
203    Ok(())
204}
205
206pub fn inject_env(lua: &Lua, env: &std::collections::HashMap<String, String>) -> Result<()> {
207    if env.is_empty() {
208        return Ok(());
209    }
210    let globals = lua.globals();
211    let env_table: mlua::Table = globals.get("env").map_err(lua_err)?;
212    let check_env: mlua::Table = env_table.get("_check_env").map_err(lua_err)?;
213    for (k, v) in env {
214        check_env.set(k.as_str(), v.as_str()).map_err(lua_err)?;
215    }
216    Ok(())
217}
assay/lua/mod.rs

assay/lua/
mod.rs
