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Merged
ndizazzo merged 2 commits into from
Aug 14, 2026
Merged

CI: classify rejected Depot cache endpoint #1323

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d4df54e
CI: classify rejected Depot cache endpoint
ndizazzo Aug 14, 2026
4b9f292
CI: cover userinfo endpoint port redaction
ndizazzo Aug 14, 2026
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86 changes: 83 additions & 3 deletions .github/workflows/depot-canary.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,86 @@ jobs:
(( port >= 1 && port <= 65535 ))
}

endpoint_scheme() {
local endpoint="$1"
local endpoint_lower
endpoint_lower="$(printf '%s' "$endpoint" | tr '[:upper:]' '[:lower:]')"
case "$endpoint_lower" in
https://*) printf 'https' ;;
http://*) printf 'http' ;;
*) printf 'other' ;;
esac
}

endpoint_authority_class() {
local endpoint="$1"
local endpoint_lower
endpoint_lower="$(printf '%s' "$endpoint" | tr '[:upper:]' '[:lower:]')"
local authority
authority="$(endpoint_host "$endpoint_lower")"
if [[ "$authority" == *"@"* ]]; then
printf 'other'
return
fi
case "$authority" in
localhost|localhost:*) printf 'localhost'; return ;;
127.0.0.1|127.0.0.1:*) printf '127.0.0.1'; return ;;
"[::1]"|"[::1]:"*) printf 'ipv6-loopback'; return ;;
esac
if [[ "$authority" =~ ^([a-z0-9-]+\.)*actions\.githubusercontent\.com(:[0-9]{1,5})?$ ]]; then
printf 'github'
return
fi
printf 'other'
}

endpoint_numeric_port() {
local endpoint="$1"
local endpoint_lower
endpoint_lower="$(printf '%s' "$endpoint" | tr '[:upper:]' '[:lower:]')"
local authority
authority="$(endpoint_host "$endpoint_lower")"
if [[ "$authority" != *"@"* ]] && [[ "$authority" =~ :[0-9]+$ ]]; then
printf 'present'
else
printf 'absent'
fi
}

endpoint_explicit_path() {
local endpoint="$1"
local endpoint_lower
endpoint_lower="$(printf '%s' "$endpoint" | tr '[:upper:]' '[:lower:]')"
case "$endpoint_lower" in
*://*) ;;
*) printf 'absent'; return ;;
esac
local remainder="${endpoint_lower#*://}"
local authority="${remainder%%[/?#]*}"
local suffix="${remainder#"$authority"}"
if [[ "$suffix" == /* ]]; then
printf 'present'
else
printf 'absent'
fi
}

report_endpoint_rejection() {
local endpoint_name="$1"
local endpoint="$2"
local scheme_label
scheme_label="$(endpoint_scheme "$endpoint")"
local authority_label
authority_label="$(endpoint_authority_class "$endpoint")"
local numeric_port_label
numeric_port_label="$(endpoint_numeric_port "$endpoint")"
local explicit_path_label
explicit_path_label="$(endpoint_explicit_path "$endpoint")"
printf 'GitHub Actions endpoint rejected (variable=%s scheme=%s authority=%s numeric_port=%s explicit_path=%s)\n' \
"$endpoint_name" "$scheme_label" "$authority_label" \
"$numeric_port_label" "$explicit_path_label" >&2
}

for endpoint_name in ACTIONS_CACHE_URL ACTIONS_RESULTS_URL ACTIONS_RUNTIME_URL; do
endpoint="${!endpoint_name:-}"
if [[ -z "$endpoint" ]]; then
Expand All @@ -138,16 +218,16 @@ jobs:
# lookalike host suffixes.
authority="$(endpoint_host "$endpoint_lower")"
if [[ "$endpoint_lower" == *depot.dev* ]]; then
echo "GitHub Actions cache was transparently redirected to Depot ($endpoint_name)" >&2
report_endpoint_rejection "$endpoint_name" "$endpoint"
exit 1
fi
if [[ "$authority" == *"@"* ]]; then
echo "GitHub Actions endpoint contains URL userinfo ($endpoint_name)" >&2
report_endpoint_rejection "$endpoint_name" "$endpoint"
exit 1
fi
if ! is_github_endpoint "$endpoint" &&
! is_loopback_endpoint "$endpoint"; then
echo "GitHub Actions endpoint is not GitHub-owned or loopback ($endpoint_name)" >&2
report_endpoint_rejection "$endpoint_name" "$endpoint"
exit 1
fi
done
Expand Down
154 changes: 128 additions & 26 deletions scripts/tests/test_depot_canary_workflow.py
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Original file line number Diff line number Diff line change
Expand Up @@ -56,21 +56,20 @@ def test_canary_fails_closed_on_cache_and_registry_injection(self) -> None:
self.assertIn('for endpoint_name in ACTIONS_CACHE_URL ACTIONS_RESULTS_URL ACTIONS_RUNTIME_URL; do', self.workflow)
self.assertIn('endpoint_host() {', self.workflow)
self.assertIn('is_loopback_endpoint() {', self.workflow)
self.assertIn('endpoint_scheme() {', self.workflow)
self.assertIn('endpoint_authority_class() {', self.workflow)
self.assertIn('endpoint_numeric_port() {', self.workflow)
self.assertIn('endpoint_explicit_path() {', self.workflow)
self.assertIn('report_endpoint_rejection() {', self.workflow)
self.assertIn(r"\[::1\]", self.workflow)
self.assertIn("numeric", self.workflow.lower())
self.assertIn("transparently redirected to Depot", self.workflow)
self.assertIn(
'GitHub Actions cache was transparently redirected to Depot ($endpoint_name)',
self.workflow,
)
self.assertIn(
'GitHub Actions endpoint contains URL userinfo ($endpoint_name)',
self.workflow,
)
self.assertIn(
'GitHub Actions endpoint is not GitHub-owned or loopback ($endpoint_name)',
'GitHub Actions endpoint rejected (variable=%s scheme=%s authority=%s numeric_port=%s explicit_path=%s)',
self.workflow,
)
self.assertNotIn('GitHub Actions cache was transparently redirected to Depot ($endpoint_name)', self.workflow)
self.assertNotIn('GitHub Actions endpoint contains URL userinfo ($endpoint_name)', self.workflow)
self.assertNotIn('GitHub Actions endpoint is not GitHub-owned or loopback ($endpoint_name)', self.workflow)
self.assertIn("ACTIONS_RESULTS_URL", self.workflow)
self.assertIn("actions\\.githubusercontent\\.com", self.workflow)
self.assertNotIn(",,}", self.workflow)
Expand Down Expand Up @@ -325,32 +324,135 @@ def run_probe(
(
"unsupported host",
"https://cache.example.invalid/cache",
"GitHub Actions endpoint is not GitHub-owned or loopback",
"https",
"other",
"absent",
"present",
),
(
"Depot redirect",
"https://cache.depot.dev/cache",
"GitHub Actions cache was transparently redirected to Depot",
"https",
"other",
"absent",
"present",
),
(
"URL userinfo",
"https://user@attacker.example/cache",
"https",
"other",
"absent",
"present",
),
(
"URL userinfo with numeric port",
"https://actions.githubusercontent.com:443@attacker.example/",
"GitHub Actions endpoint contains URL userinfo",
"https",
"other",
"absent",
"present",
),
(
"numeric port",
"https://cache.example.invalid:8443/cache",
"https",
"other",
"present",
"present",
),
(
"GitHub authority with HTTP",
"http://actions.githubusercontent.com/cache",
"http",
"github",
"absent",
"present",
),
(
"other scheme",
"ftp://cache.example.invalid/cache",
"other",
"other",
"absent",
"present",
),
(
"localhost authority",
"http://localhost/cache",
"http",
"localhost",
"absent",
"present",
),
(
"IPv4 loopback authority",
"http://127.0.0.1:12345",
"http",
"127.0.0.1",
"present",
"absent",
),
(
"IPv6 loopback authority",
"http://[::1]:65536/cache",
"http",
"ipv6-loopback",
"present",
"present",
),
)
for diagnostic, endpoint, message in diagnostic_cases:
with self.subTest(script=script_name, diagnostic=diagnostic):
result = run_probe(
script,
endpoint,
valid_endpoints[0][1],
)
self.assertNotEqual(result.returncode, 0)
self.assertIn(
f"{message} (ACTIONS_CACHE_URL)",
result.stderr,
)
self.assertNotIn(endpoint, result.stderr)
for endpoint_name in (
"ACTIONS_CACHE_URL",
"ACTIONS_RESULTS_URL",
"ACTIONS_RUNTIME_URL",
):
for (
diagnostic,
endpoint,
scheme,
authority,
numeric_port,
explicit_path,
) in diagnostic_cases:
with self.subTest(
script=script_name,
endpoint_name=endpoint_name,
diagnostic=diagnostic,
):
cache_url = endpoint if endpoint_name == "ACTIONS_CACHE_URL" else valid_endpoints[0][0]
results_url = endpoint if endpoint_name == "ACTIONS_RESULTS_URL" else valid_endpoints[0][1]
extra_environment = (
{"ACTIONS_RUNTIME_URL": endpoint}
if endpoint_name == "ACTIONS_RUNTIME_URL"
else {}
)
result = run_probe(
script,
cache_url,
results_url,
**extra_environment,
)
self.assertNotEqual(result.returncode, 0)
expected = (
"GitHub Actions endpoint rejected "
f"(variable={endpoint_name} scheme={scheme} "
f"authority={authority} numeric_port={numeric_port} "
f"explicit_path={explicit_path})"
)
self.assertIn(expected, result.stderr)
self.assertNotIn(endpoint, result.stderr)
for forbidden_fragment in (
"cache.example.invalid",
"cache.depot.dev",
"attacker.example",
"actions.githubusercontent.com",
"/cache",
"8443",
"65536",
"443",
):
self.assertNotIn(forbidden_fragment, result.stderr)
if script_name == "audit action":
with self.subTest(script=script_name, policy="native cache enabled"):
result = run_probe(
Expand Down
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