fix: drop CAP_NET_ADMIN from Cloud Hypervisor VMM by lpcox · Pull Request #7887 · github/gh-aw-firewall

lpcox · 2026-08-31T14:20:45Z

Summary

launch Cloud Hypervisor with empty inheritable, permitted, effective, bounding, and ambient capability sets while retaining only the /dev/kvm supplementary group
rely on the pre-created, VMM-owned, vnet_hdr TAP and narrow Landlock access from the TAP sysfs directory to only tun_flags
update focused unit and live-KVM assertions to require zero capabilities

Security rationale

This closes the capability gap with github/agent-microvm v0.9.0 at commit 9ca223049a3af490df168cbb74233ab438aceefb. The prior launcher retained CAP_NET_ADMIN because a vm.boot Landlock denial reading TAP flags was attributed to TAP configuration. AWF already creates, configures, owns, and brings up the TAP before launching the VMM. Granting read-only access to its tun_flags attribute lets Cloud Hypervisor reopen the TAP without a capability. A compromised VMM can no longer reconfigure namespace interfaces or firewall policy, and a zero bounding set prevents capability recovery.

Validation

npm test -- --runInBand src/cloud-hypervisor/launcher.test.ts src/cloud-hypervisor/vm-config-builder.test.ts src/microvm/network.test.ts scripts/ci/cloud-hypervisor-ci-scripts.test.ts (74 tests passed)
npm run build
npm run type-check
bash -n scripts/ci/cloud-hypervisor-live-smoke.sh
targeted ESLint (0 errors; existing warnings only)

Pre-create and own the TAP for the VMM identity. Narrow Landlock access to tun_flags and launch Cloud Hypervisor with empty capability sets. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

github-actions · 2026-08-31T14:21:11Z

Documentation Preview

Documentation build failed for this PR. View logs.

Built from commit 80f51a4

github-actions · 2026-08-31T14:21:31Z

🚀 Security Guard has started processing this pull request

Copilot

Copilot review overview

🔵 Needs a closer look

The security-critical capability and Landlock boundary should receive final human review with live-KVM confirmation.

Review tier: Balanced
Findings: None

What changed in this PR

Removes CAP_NET_ADMIN from the Cloud Hypervisor VMM while preserving TAP access through ownership and a narrowly scoped Landlock rule.

Changes:

Empties all VMM capability sets.
Restricts TAP sysfs access to tun_flags.
Updates unit, live-security, and documentation assertions.

File	Description
`src/cloud-hypervisor/launcher.ts`	Drops capabilities and narrows Landlock access.
`src/cloud-hypervisor/launcher.test.ts`	Verifies zero-capability launch arguments and rules.
`scripts/ci/cloud-hypervisor-live-smoke.sh`	Checks all capability sets and TAP rule live.
`scripts/ci/cloud-hypervisor-ci-scripts.test.ts`	Verifies smoke-test coverage.
`docs/INTEGRATION-TESTS.md`	Documents updated security assertions.
`docs/cloud-hypervisor-foundation.md`	Updates confinement and troubleshooting guidance.
`docs/architecture.md`	Reflects the zero-capability VMM boundary.

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github-actions · 2026-08-31T14:25:28Z

✅ Coverage Check Passed

Overall Coverage

Metric	Base	PR	Delta
Lines	93.86%	93.88%	📈 +0.02%
Statements	92.67%	92.69%	📈 +0.02%
Functions	93.24%	93.24%	➡️ +0.00%
Branches	86.14%	86.16%	📈 +0.02%

📁 Per-file Coverage Changes (1 files)

File	Lines (Before → After)	Statements (Before → After)
`src/log-directory-setup.ts`	96.2% → 100.0% (+3.78%)	96.3% → 100.0% (+3.71%)

Coverage comparison generated by scripts/ci/compare-coverage.ts

Copilot

Copilot review overview

🔵 Needs a closer look

The security-critical capability change depends on live KVM behavior not demonstrated by the listed validation.

Review tier: Balanced
Findings: None

github-actions · 2026-08-31T14:48:57Z

✨ The prophecy is fulfilled... Smoke Codex has completed its mystical journey. The stars align. 🌟

Warning

Firewall blocked 2 domains

The following domains were blocked by the firewall during workflow execution:

msfeed25.pkgs.visualstudio.com
registry.npmjs.org

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "msfeed25.pkgs.visualstudio.com"
    - "registry.npmjs.org"

See Network Configuration for more information.

🔮 The oracle has spoken through Smoke Codex

github-actions · 2026-08-31T14:48:58Z

✅ Smoke Copilot BYOK AOAI (api-key) completed. Copilot AOAI BYOK (api-key) mode operational. 🔓

🔑 BYOK (AOAI api-key) report filed by Smoke Copilot BYOK AOAI (api-key)

github-actions · 2026-08-31T14:48:58Z

🛡️ Smoke Copilot Network Isolation confirmed the egress allowlist is enforced. ✅

Warning

Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

example.com

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "example.com"

See Network Configuration for more information.

🛡️ Egress verdict from Smoke Copilot Network Isolation

github-actions · 2026-08-31T14:48:59Z

📡 Smoke OTel Tracing completed. All tracing scenarios validated. ✅

📡 OTel tracing validated by Smoke OTel Tracing

github-actions · 2026-08-31T14:48:59Z

📰 VERDICT: Smoke Docker Sbx has concluded. All systems operational. This is a developing story. 🎤

📰 BREAKING: Report filed by Smoke Docker Sbx

github-actions · 2026-08-31T14:49:00Z

Chroot tests passed! Smoke Chroot - All security and functionality tests succeeded.

Tested by Smoke Chroot

github-actions · 2026-08-31T14:49:00Z

✅ Smoke Copilot BYOK completed. Copilot BYOK mode operational. 🔓

🔑 BYOK report filed by Smoke Copilot BYOK

github-actions · 2026-08-31T14:49:01Z

🚀 Security Guard has started processing this pull request

github-actions · 2026-08-31T14:49:15Z

📰 VERDICT: Smoke Copilot has concluded. All systems operational. This is a developing story. 🎤

📰 BREAKING: Report filed by Smoke Copilot

github-actions · 2026-08-31T14:49:18Z

✅ Smoke Claude passed

Warning

Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

api.anthropic.com

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "api.anthropic.com"

See Network Configuration for more information.

Generated by Smoke Claude for #7887

github-actions · 2026-08-31T14:49:21Z

✅ Build Test Suite completed successfully!

Generated by Build Test Suite for #7887

github-actions · 2026-08-31T14:49:26Z

❌ Smoke Gemini reports failed. Facets need polishing...

💎 Faceted by Smoke Gemini

github-actions · 2026-08-31T14:49:32Z

❌ Contribution Check failed. Please review the logs for details.

Generated by Contribution Check for #7887

github-actions · 2026-08-31T14:49:32Z

✅ Smoke Copilot BYOK AOAI (Entra) completed. Copilot AOAI BYOK (Entra) mode operational. 🔓

🪪 BYOK (AOAI Entra) report filed by Smoke Copilot BYOK AOAI (Entra)

github-actions · 2026-08-31T14:49:37Z

🔌 Smoke Services — All services reachable! ✅

🔌 Service connectivity validated by Smoke Services

github-actions · 2026-08-31T14:52:22Z

Smoke Test: Copilot BYOK (Direct Mode) ✅

Status: PASS

All tests verified:

✅ GitHub MCP: PR list successful (PR docs: add B28 runner-doctor coverage for private-CA api-proxy TLS failures #7871, chore(deps): update safe patch dependencies #7869)
✅ GitHub.com Connectivity: HTTP 200
✅ File Write/Read: smoke-test-copilot-byok.txt verified
✅ BYOK Inference: Agent responding (direct BYOK mode active)

Running in direct BYOK mode (COPILOT_PROVIDER_API_KEY via api-proxy → api.githubcopilot.com)

🔑 BYOK report filed by Smoke Copilot BYOK
_{Add label ready-for-aw to run again}

github-actions · 2026-08-31T14:52:31Z

Smoke Test: Copilot Engine — @lpcox

✅ GitHub MCP connectivity (list_pull_requests OK)
✅ GitHub.com connectivity (HTTP 200)
✅ File write/read test (smoke-test-copilot-33404795078.txt)

Overall: PASS

📰 BREAKING: Report filed by Smoke Copilot
_{Add label ready-for-aw to run again}

github-actions · 2026-08-31T14:52:37Z

Smoke Test: Claude Engine Validation

Check	Status
API	✅ PASS
GitHub CLI	✅ PASS
File	✅ PASS

Overall result: PASS

Warning

Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

api.anthropic.com

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "api.anthropic.com"

See Network Configuration for more information.

Generated by Smoke Claude for #7887 · claude · haiku45 · 56 AIC · ⊞ 4.5K · ◷
_{Add label ready-for-aw to run again}

github-actions · 2026-08-31T14:52:40Z

EGRESS_RESULT allow=pass deny=pass

✅ Allowed domain (github.com) reachable: allowed=200
✅ Blocked domain (example.com) denied: CONNECT tunnel failed, response 403

Overall: PASS

@lpcox

Warning

Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

example.com

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "example.com"

See Network Configuration for more information.

🛡️ Egress verdict from Smoke Copilot Network Isolation
_{Add label ready-for-aw to run again}

github-actions · 2026-08-31T14:53:02Z

Smoke Test: Docker Sbx Validation

PR: fix: drop CAP_NET_ADMIN from Cloud Hypervisor VMM (#7887)

✅ GitHub MCP connectivity (verified via list_pull_requests)
✅ GitHub.com connectivity (HTTP 200)
✅ File write/read test

Overall: PASS

cc @lpcox

📰 BREAKING: Report filed by Smoke Docker Sbx
_{Add label ready-for-aw to run again}

github-actions · 2026-08-31T14:53:37Z

Chroot Version Comparison Results

Runtime	Host Version	Chroot Version	Match?
Python	Python 3.12.14	Python 3.12.14	✅ YES
Node.js	v24.19.0	v22.23.2	❌ NO
Go	go1.22.12	go1.22.12	✅ YES

Overall: FAILED — Node.js version mismatch between host and chroot environment. smoke-chroot label not applied.

Tested by Smoke Chroot
_{Add label ready-for-aw to run again}

github-actions · 2026-08-31T14:54:12Z

Smoke Test Results:

Redis: ❌ (DNS resolution failure for host.docker.internal)
PostgreSQL pg_isready: ❌ (no response)
PostgreSQL SELECT 1: ❌ (DNS resolution failure)

Overall: FAIL — host.docker.internal could not be resolved from the AWF sandbox.

🔌 Service connectivity validated by Smoke Services
_{Add label ready-for-aw to run again}

github-actions · 2026-08-31T14:54:24Z

@lpcox

docs: add B28 runner-doctor coverage for private-CA api-proxy TLS failures: ❌
chore(deps): update safe patch dependencies: ❌
GitHub.com connectivity: ✅
Agent file I/O: ✅
BYOK inference: ✅

Running in direct BYOK mode (COPILOT_PROVIDER_API_KEY + COPILOT_PROVIDER_BASE_URL) via api-proxy → Azure OpenAI (Foundry, o4-mini-aw)

Overall status: FAIL

🔑 BYOK (AOAI api-key) report filed by Smoke Copilot BYOK AOAI (api-key)
_{Add label ready-for-aw to run again}

github-actions · 2026-08-31T14:54:27Z

docs: add B28 runner-doctor coverage for private-CA api-proxy TLS failures
ochore(deps): update safe patch dependencies
GitHub MCP Testing: ❌
GitHub.com Connectivity: ✅
File Write/Read Test: ✅
BYOK Inference Test: ✅
Running in direct BYOK mode (AWF_AUTH_TYPE=github-oidc + AWF_AUTH_AZURE_* + COPILOT_PROVIDER_BASE_URL) via api-proxy → Azure OpenAI (Foundry, o4-mini-aw) authenticated via Microsoft Entra
Overall Status: FAIL
cc @lpcox

🪪 BYOK (AOAI Entra) report filed by Smoke Copilot BYOK AOAI (Entra)
_{Add label ready-for-aw to run again}

github-actions · 2026-08-31T14:54:36Z

Smoke test status: FAIL
Merged PRs: "docs: add B28 runner-doctor coverage for private-CA api-proxy TLS failures"; "chore(deps): update safe patch dependencies"
Queried PRs: "feat: isolate Cloud Hypervisor with per-run VMM identities"; "feat: reserve microVM network resources atomically"
Merged PR review ✅
GH query ✅ (used gh; safeinputs-gh unavailable)
Playwright title ✅
File write/read ✅
Discussion query ✅, discussion comment ❌
Build (npm ci && npm run build) ✅
Overall: FAIL

Warning

Firewall blocked 2 domains

The following domains were blocked by the firewall during workflow execution:

msfeed25.pkgs.visualstudio.com
registry.npmjs.org

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "msfeed25.pkgs.visualstudio.com"
    - "registry.npmjs.org"

See Network Configuration for more information.

🔮 The oracle has spoken through Smoke Codex
_{Add label ready-for-aw to run again}

github-actions · 2026-08-31T14:54:53Z

🏗️ Build Test Suite Results

Ecosystem	Project	Build/Install	Tests	Status
Bun	elysia	✅	1/1 passed	✅ PASS
Bun	hono	✅	1/1 passed	✅ PASS
C++	fmt	✅	N/A	✅ PASS
C++	json	✅	N/A	✅ PASS
Deno	oak	N/A	1/1 passed	✅ PASS
Deno	std	N/A	1/1 passed	✅ PASS
.NET	hello-world	✅	N/A (ran, "Hello, World!")	✅ PASS
.NET	json-parse	✅	N/A (ran, produced JSON output)	✅ PASS
Go	color	✅	ok	✅ PASS
Go	env	✅	ok	✅ PASS
Go	uuid	✅	ok	✅ PASS
Java	gson	✅	1/1 passed	✅ PASS
Java	caffeine	✅	1/1 passed	✅ PASS
Node.js	clsx	✅	all passed	✅ PASS
Node.js	execa	✅	all passed	✅ PASS
Node.js	p-limit	✅	all passed	✅ PASS
Rust	fd	✅	1/1 passed	✅ PASS
Rust	zoxide	✅	1/1 passed	✅ PASS

Overall: 8/8 ecosystems passed — PASS

Note: Maven's default ~/.m2 directory was owned by root in this environment (pre-existing, unrelated to the firewall), causing an initial LocalRepositoryNotAccessibleException. Worked around by pointing Maven at an alternate writable localRepository path (-s settings override); both Java projects then compiled and tested successfully through the Squid proxy with no other issues.

Generated by Build Test Suite for #7887 · copilot · auto · 38.4 AIC · ⊞ 12K · ◷
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github-actions · 2026-08-31T14:56:28Z

OTel Tracing Smoke Test Results

✅ Scenario 1 (Module Loading): otel.js loads successfully. isEnabled() → true. Exports: startRequestSpan, setTokenAttributes, setBudgetAttributes, endSpan, endSpanError, shutdown, isEnabled, plus internal helpers (_provider, _ProxyAwareOtlpExporter, _FileSpanExporter, _FanOutSpanExporter, _parseEndpoints, _parseOtlpHeaders, _buildResourceSpans, _createOtlpWorkloadIdentity).
✅ Scenario 2 (Test Suite): otel.test.js, otel-fanout.test.js, otel-workload-identity.test.js — 3 suites, 68/68 tests passed.
✅ Scenario 3 (Env Var Forwarding): env-passthrough.ts forwards GITHUB_AW_OTEL_TRACE_ID / GITHUB_AW_OTEL_PARENT_SPAN_ID to the agent; api-proxy-env-config.ts forwards GH_AW_OTLP_ENDPOINTS, OTEL_EXPORTER_OTLP_ENDPOINT, and the same trace-context vars to api-proxy.
✅ Scenario 4 (Token Tracker Integration): token-tracker-http.js implements the onUsage callback hook (invoked after normalized usage extraction) — confirmed OTEL integration point.
✅ Scenario 5 (OTEL Diagnostics): No api-proxy/otel.jsonl span file found under the sandbox firewall logs (api-proxy OTLP file-export not active this run — expected since a live Sentry OTLP endpoint was configured instead of file export); token-usage.jsonl present and populated, confirming baseline usage tracking is active. This is expected/graceful behavior, not a regression.

Summary: All scenarios pass or behave as expected during development. No regressions detected.

📡 OTel tracing validated by Smoke OTel Tracing
_{Add label ready-for-aw to run again}

fix(cloud-hypervisor): drop VMM capabilities

0e0087d

Pre-create and own the TAP for the VMM identity. Narrow Landlock access to tun_flags and launch Cloud Hypervisor with empty capability sets. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot AI balanced review requested due to automatic review settings August 31, 2026 14:20

lpcox added the cloud-hypervisor-kvm Trigger the Cloud Hypervisor live-KVM smoke/security suite label Aug 31, 2026

Copilot started reviewing on behalf of lpcox August 31, 2026 14:21 View session

Copilot AI reviewed Aug 31, 2026

View reviewed changes

lpcox requested a balanced review from Copilot August 31, 2026 14:39

Copilot started reviewing on behalf of lpcox August 31, 2026 14:40 View session

Copilot AI reviewed Aug 31, 2026

View reviewed changes

lpcox changed the title ~~Drop CAP_NET_ADMIN from Cloud Hypervisor VMM~~ fix: drop CAP_NET_ADMIN from Cloud Hypervisor VMM Aug 31, 2026

lpcox added the ready-for-aw label Aug 31, 2026

lpcox temporarily deployed to aoai-model August 31, 2026 14:49 — with GitHub Actions Inactive

github-actions Bot added the smoke-copilot-byok label Aug 31, 2026

github-actions Bot added the smoke-copilot label Aug 31, 2026

github-actions Bot added smoke-claude smoke-copilot-network-isolation Copilot network-isolation egress smoke test labels Aug 31, 2026

github-actions Bot added the smoke-docker-sbx label Aug 31, 2026

lpcox temporarily deployed to aoai-model August 31, 2026 14:54 — with GitHub Actions Inactive

github-actions Bot added the smoke-copilot-byok-aoai-apikey label Aug 31, 2026

github-actions Bot added the smoke-copilot-byok-aoai-entra label Aug 31, 2026

lpcox temporarily deployed to aoai-model August 31, 2026 14:54 — with GitHub Actions Inactive

github-actions Bot added the build-test label Aug 31, 2026

github-actions Bot mentioned this pull request Aug 31, 2026

[aw] Contribution Check hit engine rate limit (HTTP 429) #7895

Closed

lpcox merged commit eeef497 into main Aug 31, 2026
306 of 309 checks passed

lpcox deleted the lpcox-zero-cap-vmm branch August 31, 2026 15:09

This was referenced Aug 31, 2026

feat: require explicit Cloud Hypervisor tool-cache mounts #7888

Merged

fix: filter workflow commands from microVM output #7892

Merged

feat: verify Cloud Hypervisor runtime confinement #7889

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lpcox commented Aug 31, 2026

Summary

Security rationale

Validation

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🔵 Needs a closer look

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✅ Coverage Check Passed

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Smoke Test: Copilot BYOK (Direct Mode) ✅

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Smoke Test: Claude Engine Validation

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