1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669//! Host function implementations for the WASM sandbox.
//!
//! Each function checks capabilities before executing. Deny-by-default:
//! if no matching capability is found, the operation is rejected.
//!
//! These functions are called from the `host_call` dispatch in `sandbox.rs`.
//! They receive `&GuestState` (not `&mut`) and return JSON values.
use crate::sandbox::GuestState;
use openfang_types::capability::{capability_matches, Capability};
use serde_json::json;
use std::net::ToSocketAddrs;
use std::path::{Component, Path};
use tracing::debug;
/// Dispatch a host call to the appropriate handler.
///
/// Returns JSON: `{"ok": ...}` on success, `{"error": "..."}` on failure.
pub fn dispatch(state: &GuestState, method: &str, params: &serde_json::Value) -> serde_json::Value {
debug!(method, "WASM host_call dispatch");
match method {
// Always allowed (no capability check)
"time_now" => host_time_now(),
// Filesystem — requires FileRead/FileWrite
"fs_read" => host_fs_read(state, params),
"fs_write" => host_fs_write(state, params),
"fs_list" => host_fs_list(state, params),
// Network — requires NetConnect
"net_fetch" => host_net_fetch(state, params),
// Shell — requires ShellExec
"shell_exec" => host_shell_exec(state, params),
// Environment — requires EnvRead
"env_read" => host_env_read(state, params),
// Memory KV — requires MemoryRead/MemoryWrite
"kv_get" => host_kv_get(state, params),
"kv_set" => host_kv_set(state, params),
// Agent interaction — requires AgentMessage/AgentSpawn
"agent_send" => host_agent_send(state, params),
"agent_spawn" => host_agent_spawn(state, params),
_ => json!({"error": format!("Unknown host method: {method}")}),
}
}
// ---------------------------------------------------------------------------
// Capability checking
// ---------------------------------------------------------------------------
/// Check that the guest has a capability matching `required`.
/// Returns `Ok(())` if granted, `Err(json)` with an error response if denied.
fn check_capability(
capabilities: &[Capability],
required: &Capability,
) -> Result<(), serde_json::Value> {
for granted in capabilities {
if capability_matches(granted, required) {
return Ok(());
}
}
Err(json!({"error": format!("Capability denied: {required:?}")}))
}
// ---------------------------------------------------------------------------
// Path traversal protection
// ---------------------------------------------------------------------------
/// Secure path resolution — NEVER returns raw unchecked paths.
/// Rejects traversal components, resolves symlinks where possible.
fn safe_resolve_path(path: &str) -> Result<std::path::PathBuf, serde_json::Value> {
let p = Path::new(path);
// Phase 1: Reject any path with ".." components (even if they'd resolve safely)
for component in p.components() {
if matches!(component, Component::ParentDir) {
return Err(json!({"error": "Path traversal denied: '..' components forbidden"}));
}
}
// Phase 2: Canonicalize to resolve symlinks and normalize
std::fs::canonicalize(p).map_err(|e| json!({"error": format!("Cannot resolve path: {e}")}))
}
/// For writes where the file may not exist yet: canonicalize the parent, validate the filename.
fn safe_resolve_parent(path: &str) -> Result<std::path::PathBuf, serde_json::Value> {
let p = Path::new(path);
for component in p.components() {
if matches!(component, Component::ParentDir) {
return Err(json!({"error": "Path traversal denied: '..' components forbidden"}));
}
}
let parent = p
.parent()
.filter(|par| !par.as_os_str().is_empty())
.ok_or_else(|| json!({"error": "Invalid path: no parent directory"}))?;
let canonical_parent = std::fs::canonicalize(parent)
.map_err(|e| json!({"error": format!("Cannot resolve parent directory: {e}")}))?;
let file_name = p
.file_name()
.ok_or_else(|| json!({"error": "Invalid path: no file name"}))?;
// Double-check filename doesn't contain traversal (belt-and-suspenders)
if file_name.to_string_lossy().contains("..") {
return Err(json!({"error": "Path traversal denied in file name"}));
}
Ok(canonical_parent.join(file_name))
}
// ---------------------------------------------------------------------------
// SSRF protection
// ---------------------------------------------------------------------------
/// SSRF protection: check if a hostname resolves to a private/internal IP.
/// This defeats DNS rebinding by checking the RESOLVED address, not the hostname.
fn is_ssrf_target(url: &str) -> Result<(), serde_json::Value> {
// Only allow http:// and https:// schemes (block file://, gopher://, ftp://)
if !url.starts_with("http://") && !url.starts_with("https://") {
return Err(json!({"error": "Only http:// and https:// URLs are allowed"}));
}
let host = extract_host_from_url(url);
let hostname = host.split(':').next().unwrap_or(&host);
// Check hostname-based blocklist first (catches metadata endpoints)
let blocked_hostnames = [
"localhost",
"metadata.google.internal",
"metadata.aws.internal",
"instance-data",
"169.254.169.254",
];
if blocked_hostnames.contains(&hostname) {
return Err(json!({"error": format!("SSRF blocked: {hostname} is a restricted hostname")}));
}
// Resolve DNS and check every returned IP
let port = if url.starts_with("https") { 443 } else { 80 };
let socket_addr = format!("{hostname}:{port}");
if let Ok(addrs) = socket_addr.to_socket_addrs() {
for addr in addrs {
let ip = addr.ip();
if ip.is_loopback() || ip.is_unspecified() || is_private_ip(&ip) {
return Err(json!({"error": format!(
"SSRF blocked: {hostname} resolves to private IP {ip}"
)}));
}
}
}
Ok(())
}
fn is_private_ip(ip: &std::net::IpAddr) -> bool {
match ip {
std::net::IpAddr::V4(v4) => {
let octets = v4.octets();
matches!(
octets,
[10, ..] | [172, 16..=31, ..] | [192, 168, ..] | [169, 254, ..]
)
}
std::net::IpAddr::V6(v6) => {
let segments = v6.segments();
(segments[0] & 0xfe00) == 0xfc00 || (segments[0] & 0xffc0) == 0xfe80
}
}
}
// ---------------------------------------------------------------------------
// Always-allowed functions
// ---------------------------------------------------------------------------
fn host_time_now() -> serde_json::Value {
let now = std::time::SystemTime::now()
.duration_since(std::time::UNIX_EPOCH)
.unwrap_or_default()
.as_secs();
json!({"ok": now})
}
// ---------------------------------------------------------------------------
// Filesystem (capability-checked)
// ---------------------------------------------------------------------------
fn host_fs_read(state: &GuestState, params: &serde_json::Value) -> serde_json::Value {
let path = match params.get("path").and_then(|p| p.as_str()) {
Some(p) => p,
None => return json!({"error": "Missing 'path' parameter"}),
};
// Check capability with raw path first
if let Err(e) = check_capability(&state.capabilities, &Capability::FileRead(path.to_string())) {
return e;
}
// SECURITY: Reject path traversal after capability gate
let canonical = match safe_resolve_path(path) {
Ok(c) => c,
Err(e) => return e,
};
match std::fs::read_to_string(&canonical) {
Ok(content) => json!({"ok": content}),
Err(e) => json!({"error": format!("fs_read failed: {e}")}),
}
}
fn host_fs_write(state: &GuestState, params: &serde_json::Value) -> serde_json::Value {
let path = match params.get("path").and_then(|p| p.as_str()) {
Some(p) => p,
None => return json!({"error": "Missing 'path' parameter"}),
};
let content = match params.get("content").and_then(|c| c.as_str()) {
Some(c) => c,
None => return json!({"error": "Missing 'content' parameter"}),
};
// Check capability with raw path first
if let Err(e) = check_capability(
&state.capabilities,
&Capability::FileWrite(path.to_string()),
) {
return e;
}
// SECURITY: Reject path traversal after capability gate
let write_path = match safe_resolve_parent(path) {
Ok(p) => p,
Err(e) => return e,
};
match std::fs::write(&write_path, content) {
Ok(()) => json!({"ok": true}),
Err(e) => json!({"error": format!("fs_write failed: {e}")}),
}
}
fn host_fs_list(state: &GuestState, params: &serde_json::Value) -> serde_json::Value {
let path = match params.get("path").and_then(|p| p.as_str()) {
Some(p) => p,
None => return json!({"error": "Missing 'path' parameter"}),
};
// Check capability with raw path first
if let Err(e) = check_capability(&state.capabilities, &Capability::FileRead(path.to_string())) {
return e;
}
// SECURITY: Reject path traversal after capability gate
let canonical = match safe_resolve_path(path) {
Ok(c) => c,
Err(e) => return e,
};
match std::fs::read_dir(&canonical) {
Ok(entries) => {
let names: Vec<String> = entries
.filter_map(|e| e.ok())
.map(|e| e.file_name().to_string_lossy().to_string())
.collect();
json!({"ok": names})
}
Err(e) => json!({"error": format!("fs_list failed: {e}")}),
}
}
// ---------------------------------------------------------------------------
// Network (capability-checked)
// ---------------------------------------------------------------------------
fn host_net_fetch(state: &GuestState, params: &serde_json::Value) -> serde_json::Value {
let url = match params.get("url").and_then(|u| u.as_str()) {
Some(u) => u,
None => return json!({"error": "Missing 'url' parameter"}),
};
let method = params
.get("method")
.and_then(|m| m.as_str())
.unwrap_or("GET");
let body = params.get("body").and_then(|b| b.as_str()).unwrap_or("");
// SECURITY: SSRF protection — check resolved IP against private ranges
if let Err(e) = is_ssrf_target(url) {
return e;
}
// Extract host:port from URL for capability check
let host = extract_host_from_url(url);
if let Err(e) = check_capability(&state.capabilities, &Capability::NetConnect(host)) {
return e;
}
state.tokio_handle.block_on(async {
let client = reqwest::Client::new();
let request = match method.to_uppercase().as_str() {
"POST" => client.post(url).body(body.to_string()),
"PUT" => client.put(url).body(body.to_string()),
"DELETE" => client.delete(url),
_ => client.get(url),
};
match request.send().await {
Ok(resp) => {
let status = resp.status().as_u16();
match resp.text().await {
Ok(text) => json!({"ok": {"status": status, "body": text}}),
Err(e) => json!({"error": format!("Failed to read response: {e}")}),
}
}
Err(e) => json!({"error": format!("Request failed: {e}")}),
}
})
}
/// Extract host:port from a URL for capability checking.
fn extract_host_from_url(url: &str) -> String {
if let Some(after_scheme) = url.split("://").nth(1) {
let host_port = after_scheme.split('/').next().unwrap_or(after_scheme);
if host_port.contains(':') {
host_port.to_string()
} else if url.starts_with("https") {
format!("{host_port}:443")
} else {
format!("{host_port}:80")
}
} else {
url.to_string()
}
}
// ---------------------------------------------------------------------------
// Shell (capability-checked)
// ---------------------------------------------------------------------------
fn host_shell_exec(state: &GuestState, params: &serde_json::Value) -> serde_json::Value {
let command = match params.get("command").and_then(|c| c.as_str()) {
Some(c) => c,
None => return json!({"error": "Missing 'command' parameter"}),
};
if let Err(e) = check_capability(
&state.capabilities,
&Capability::ShellExec(command.to_string()),
) {
return e;
}
let args: Vec<&str> = params
.get("args")
.and_then(|a| a.as_array())
.map(|arr| arr.iter().filter_map(|v| v.as_str()).collect())
.unwrap_or_default();
// Command::new does NOT use a shell — safe from shell injection.
// Each argument is passed directly to the process.
match std::process::Command::new(command).args(&args).output() {
Ok(output) => {
let stdout = String::from_utf8_lossy(&output.stdout).to_string();
let stderr = String::from_utf8_lossy(&output.stderr).to_string();
json!({
"ok": {
"exit_code": output.status.code(),
"stdout": stdout,
"stderr": stderr,
}
})
}
Err(e) => json!({"error": format!("shell_exec failed: {e}")}),
}
}
// ---------------------------------------------------------------------------
// Environment (capability-checked)
// ---------------------------------------------------------------------------
fn host_env_read(state: &GuestState, params: &serde_json::Value) -> serde_json::Value {
let name = match params.get("name").and_then(|n| n.as_str()) {
Some(n) => n,
None => return json!({"error": "Missing 'name' parameter"}),
};
if let Err(e) = check_capability(&state.capabilities, &Capability::EnvRead(name.to_string())) {
return e;
}
match std::env::var(name) {
Ok(val) => json!({"ok": val}),
Err(_) => json!({"ok": null}),
}
}
// ---------------------------------------------------------------------------
// Memory KV (capability-checked, uses kernel handle)
// ---------------------------------------------------------------------------
fn host_kv_get(state: &GuestState, params: &serde_json::Value) -> serde_json::Value {
let key = match params.get("key").and_then(|k| k.as_str()) {
Some(k) => k,
None => return json!({"error": "Missing 'key' parameter"}),
};
if let Err(e) = check_capability(
&state.capabilities,
&Capability::MemoryRead(key.to_string()),
) {
return e;
}
let kernel = match &state.kernel {
Some(k) => k,
None => return json!({"error": "No kernel handle available"}),
};
match kernel.memory_recall(key) {
Ok(Some(val)) => json!({"ok": val}),
Ok(None) => json!({"ok": null}),
Err(e) => json!({"error": e}),
}
}
fn host_kv_set(state: &GuestState, params: &serde_json::Value) -> serde_json::Value {
let key = match params.get("key").and_then(|k| k.as_str()) {
Some(k) => k,
None => return json!({"error": "Missing 'key' parameter"}),
};
let value = match params.get("value") {
Some(v) => v.clone(),
None => return json!({"error": "Missing 'value' parameter"}),
};
if let Err(e) = check_capability(
&state.capabilities,
&Capability::MemoryWrite(key.to_string()),
) {
return e;
}
let kernel = match &state.kernel {
Some(k) => k,
None => return json!({"error": "No kernel handle available"}),
};
match kernel.memory_store(key, value) {
Ok(()) => json!({"ok": true}),
Err(e) => json!({"error": e}),
}
}
// ---------------------------------------------------------------------------
// Agent interaction (capability-checked, uses kernel handle)
// ---------------------------------------------------------------------------
fn host_agent_send(state: &GuestState, params: &serde_json::Value) -> serde_json::Value {
let target = match params.get("target").and_then(|t| t.as_str()) {
Some(t) => t,
None => return json!({"error": "Missing 'target' parameter"}),
};
let message = match params.get("message").and_then(|m| m.as_str()) {
Some(m) => m,
None => return json!({"error": "Missing 'message' parameter"}),
};
if let Err(e) = check_capability(
&state.capabilities,
&Capability::AgentMessage(target.to_string()),
) {
return e;
}
let kernel = match &state.kernel {
Some(k) => k,
None => return json!({"error": "No kernel handle available"}),
};
match state
.tokio_handle
.block_on(kernel.send_to_agent(target, message))
{
Ok(response) => json!({"ok": response}),
Err(e) => json!({"error": e}),
}
}
fn host_agent_spawn(state: &GuestState, params: &serde_json::Value) -> serde_json::Value {
if let Err(e) = check_capability(&state.capabilities, &Capability::AgentSpawn) {
return e;
}
let manifest_toml = match params.get("manifest").and_then(|m| m.as_str()) {
Some(m) => m,
None => return json!({"error": "Missing 'manifest' parameter"}),
};
let kernel = match &state.kernel {
Some(k) => k,
None => return json!({"error": "No kernel handle available"}),
};
// SECURITY: Enforce capability inheritance — child <= parent
match state.tokio_handle.block_on(kernel.spawn_agent_checked(
manifest_toml,
Some(&state.agent_id),
&state.capabilities,
)) {
Ok((id, name)) => json!({"ok": {"id": id, "name": name}}),
Err(e) => json!({"error": e}),
}
}
#[cfg(test)]
mod tests {
use super::*;
fn test_state(capabilities: Vec<Capability>) -> GuestState {
GuestState {
capabilities,
kernel: None,
agent_id: "test-agent".to_string(),
tokio_handle: tokio::runtime::Handle::current(),
}
}
#[tokio::test]
async fn test_time_now_always_allowed() {
let result = host_time_now();
assert!(result.get("ok").is_some());
let ts = result["ok"].as_u64().unwrap();
assert!(ts > 1_700_000_000);
}
#[tokio::test]
async fn test_fs_read_denied_no_capability() {
let state = test_state(vec![]);
let result = host_fs_read(&state, &json!({"path": "/etc/passwd"}));
let err = result["error"].as_str().unwrap();
assert!(err.contains("denied"));
}
#[tokio::test]
async fn test_fs_write_denied_no_capability() {
let state = test_state(vec![]);
let result = host_fs_write(&state, &json!({"path": "/tmp/test", "content": "hello"}));
let err = result["error"].as_str().unwrap();
assert!(err.contains("denied"));
}
#[tokio::test]
async fn test_fs_read_granted_wildcard() {
let state = test_state(vec![Capability::FileRead("*".to_string())]);
let result = host_fs_read(&state, &json!({"path": "Cargo.toml"}));
// Should not be capability-denied (may still fail on path)
if let Some(err) = result.get("error") {
let msg = err.as_str().unwrap_or("");
assert!(
!msg.contains("denied"),
"Should not be capability-denied: {msg}"
);
}
}
#[tokio::test]
async fn test_shell_exec_denied() {
let state = test_state(vec![]);
let result = host_shell_exec(&state, &json!({"command": "ls"}));
let err = result["error"].as_str().unwrap();
assert!(err.contains("denied"));
}
#[tokio::test]
async fn test_env_read_denied() {
let state = test_state(vec![]);
let result = host_env_read(&state, &json!({"name": "HOME"}));
let err = result["error"].as_str().unwrap();
assert!(err.contains("denied"));
}
#[tokio::test]
async fn test_env_read_granted() {
let state = test_state(vec![Capability::EnvRead("PATH".to_string())]);
let result = host_env_read(&state, &json!({"name": "PATH"}));
assert!(result.get("ok").is_some(), "Expected ok: {:?}", result);
}
#[tokio::test]
async fn test_kv_get_no_kernel() {
let state = test_state(vec![Capability::MemoryRead("*".to_string())]);
let result = host_kv_get(&state, &json!({"key": "test"}));
let err = result["error"].as_str().unwrap();
assert!(err.contains("kernel"));
}
#[tokio::test]
async fn test_agent_send_denied() {
let state = test_state(vec![]);
let result = host_agent_send(&state, &json!({"target": "some-agent", "message": "hello"}));
let err = result["error"].as_str().unwrap();
assert!(err.contains("denied"));
}
#[tokio::test]
async fn test_agent_spawn_denied() {
let state = test_state(vec![]);
let result = host_agent_spawn(&state, &json!({"manifest": "name = 'test'"}));
let err = result["error"].as_str().unwrap();
assert!(err.contains("denied"));
}
#[tokio::test]
async fn test_dispatch_unknown_method() {
let state = test_state(vec![]);
let result = dispatch(&state, "bogus_method", &json!({}));
let err = result["error"].as_str().unwrap();
assert!(err.contains("Unknown"));
}
#[tokio::test]
async fn test_missing_params() {
let state = test_state(vec![Capability::FileRead("*".to_string())]);
let result = host_fs_read(&state, &json!({}));
let err = result["error"].as_str().unwrap();
assert!(err.contains("Missing"));
}
#[test]
fn test_safe_resolve_path_traversal() {
assert!(safe_resolve_path("../etc/passwd").is_err());
assert!(safe_resolve_path("/tmp/../../etc/passwd").is_err());
assert!(safe_resolve_path("foo/../bar").is_err());
}
#[test]
fn test_safe_resolve_parent_traversal() {
assert!(safe_resolve_parent("../malicious.txt").is_err());
assert!(safe_resolve_parent("/tmp/../../etc/shadow").is_err());
}
#[test]
fn test_ssrf_private_ips_blocked() {
assert!(is_ssrf_target("http://127.0.0.1:8080/secret").is_err());
assert!(is_ssrf_target("http://localhost:3000/api").is_err());
assert!(is_ssrf_target("http://169.254.169.254/metadata").is_err());
assert!(is_ssrf_target("http://metadata.google.internal/v1/instance").is_err());
}
#[test]
fn test_ssrf_public_ips_allowed() {
assert!(is_ssrf_target("https://api.openai.com/v1/chat").is_ok());
assert!(is_ssrf_target("https://google.com").is_ok());
}
#[test]
fn test_ssrf_scheme_validation() {
assert!(is_ssrf_target("file:///etc/passwd").is_err());
assert!(is_ssrf_target("gopher://evil.com").is_err());
assert!(is_ssrf_target("ftp://example.com").is_err());
}
#[test]
fn test_is_private_ip() {
use std::net::IpAddr;
assert!(is_private_ip(&"10.0.0.1".parse::<IpAddr>().unwrap()));
assert!(is_private_ip(&"172.16.0.1".parse::<IpAddr>().unwrap()));
assert!(is_private_ip(&"192.168.1.1".parse::<IpAddr>().unwrap()));
assert!(is_private_ip(&"169.254.169.254".parse::<IpAddr>().unwrap()));
assert!(!is_private_ip(&"8.8.8.8".parse::<IpAddr>().unwrap()));
assert!(!is_private_ip(&"1.1.1.1".parse::<IpAddr>().unwrap()));
}
#[test]
fn test_extract_host_from_url() {
assert_eq!(
extract_host_from_url("https://api.openai.com/v1/chat"),
"api.openai.com:443"
);
assert_eq!(
extract_host_from_url("http://localhost:8080/api"),
"localhost:8080"
);
assert_eq!(
extract_host_from_url("http://example.com"),
"example.com:80"
);
}
}