rename Fence to Greywall as GreyHaven sandboxing component

Rebrand the project from Fence to Greywall, the sandboxing layer of the
GreyHaven platform. This updates:

- Go module path to gitea.app.monadical.io/monadical/greywall
- Binary name, CLI help text, and all usage examples
- Config paths (~/.config/greywall/greywall.json), env vars (GREYWALL_*)
- Log prefixes ([greywall:*]), temp file prefixes (greywall-*)
- All documentation, scripts, CI workflows, and example files
- README rewritten with GreyHaven branding and Fence attribution

Directory/file renames: cmd/fence → cmd/greywall, pkg/fence → pkg/greywall,
docs/why-fence.md → docs/why-greywall.md, example JSON files, and banner.
This commit is contained in:
2026-02-10 16:00:24 -06:00
parent 481616455a
commit da3a2ac3a4
68 changed files with 586 additions and 586 deletions

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@@ -1,19 +1,19 @@
# Security Model
Fence is intended as defense-in-depth for running semi-trusted commands with reduced side effects (package installs, build scripts, CI jobs, unfamiliar repos).
Greywall is intended as defense-in-depth for running semi-trusted commands with reduced side effects (package installs, build scripts, CI jobs, unfamiliar repos).
It is not designed to be a strong isolation boundary against actively malicious code that is attempting to escape.
## Threat model (what Fence helps with)
## Threat model (what Greywall helps with)
Fence is useful when you want to reduce risk from:
Greywall is useful when you want to reduce risk from:
- Supply-chain scripts that unexpectedly call out to the network
- Tools that write broadly across your filesystem
- Accidental leakage of secrets via "phone home" behavior
- Unfamiliar repos that run surprising commands during install/build/test
## What Fence enforces
## What Greywall enforces
### Network
@@ -25,7 +25,7 @@ Important: domain filtering does not inspect content. If you allow a domain, cod
#### How allowlisting works
Fence combines OS-level enforcement with proxy-based allowlisting:
Greywall combines OS-level enforcement with proxy-based allowlisting:
- The OS sandbox / network namespace is expected to block direct outbound connections.
- Domain allowlisting happens via local HTTP/SOCKS proxies and proxy environment variables (`HTTP_PROXY`, `HTTPS_PROXY`, `ALL_PROXY`).
@@ -41,11 +41,11 @@ Localhost is separate from "external domains":
- **Writes are denied by default**; you must opt in with `allowWrite`.
- **denyWrite** can block specific files/patterns even if the parent directory is writable.
- **denyRead** can block reads from sensitive paths.
- Fence includes an internal list of always-protected targets (e.g. shell configs, git hooks) to reduce common persistence vectors.
- Greywall includes an internal list of always-protected targets (e.g. shell configs, git hooks) to reduce common persistence vectors.
### Environment sanitization
Fence strips dangerous environment variables before passing them to sandboxed commands:
Greywall strips dangerous environment variables before passing them to sandboxed commands:
- `LD_*` (Linux): `LD_PRELOAD`, `LD_LIBRARY_PATH`, etc.
- `DYLD_*` (macOS): `DYLD_INSERT_LIBRARIES`, `DYLD_LIBRARY_PATH`, etc.
@@ -57,11 +57,11 @@ This prevents a library injection attack where a sandboxed process writes a mali
- `-m/--monitor` helps you discover what a command *tries* to access (blocked only).
- `-d/--debug` shows more detail to understand why something was blocked.
## Limitations (what Fence does NOT try to solve)
## Limitations (what Greywall does NOT try to solve)
- **Hostile code containment**: assume determined attackers may escape via kernel/OS vulnerabilities.
- **Resource limits**: CPU, memory, disk, fork bombs, etc. are out of scope.
- **Content-based controls**: Fence does not block data exfiltration to *allowed* destinations.
- **Content-based controls**: Greywall does not block data exfiltration to *allowed* destinations.
- **Proxy limitations / protocol edge cases**: some programs may not respect proxy environment variables, so they won't get domain allowlisting unless you configure them to use a proxy (e.g. Node.js `http`/`https` without a proxy-aware client).
### Practical examples of proxy limitations
@@ -71,14 +71,14 @@ The proxy approach works well for many tools (curl, wget, git, npm, pip), but no
- Node.js native `http`/`https` (use a proxy-aware client, e.g. `undici` + `ProxyAgent`)
- Raw socket connections (custom TCP/UDP protocols)
Fence's OS-level sandbox is still expected to block direct outbound connections; bypassing the proxy should fail rather than silently succeeding.
Greywall's OS-level sandbox is still expected to block direct outbound connections; bypassing the proxy should fail rather than silently succeeding.
### Domain-based filtering only
Fence does not inspect request content. If you allow a domain, a sandboxed process can still exfiltrate data to that domain.
Greywall does not inspect request content. If you allow a domain, a sandboxed process can still exfiltrate data to that domain.
### Not a hostile-code containment boundary
Fence is defense-in-depth for running semi-trusted code, not a strong isolation boundary against malware designed to escape sandboxes.
Greywall is defense-in-depth for running semi-trusted code, not a strong isolation boundary against malware designed to escape sandboxes.
For implementation details (how proxies/sandboxes/bridges work), see [`ARCHITECTURE.md`](../ARCHITECTURE.md).