Files
webhooker/internal/delivery/ssrf_test.go
sneak f9362101e6
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Add an egress CIDR allowlist to the SSRF guard (closes #204)
The SSRF blocklist had no escape hatch, so the thing webhooker is
mostly for — taking a public webhook and forwarding it to something
on your own network — could not be configured at all. Every private
address, Docker sibling and loopback service was permanently
unreachable as a delivery destination.

ALLOWED_EGRESS_CIDRS (default empty) names blocks that delivery
targets may reach despite the default blocklist. It is an allowlist
and only ever adds destinations: there is no boolean, and no value
disables SSRF protection wholesale. Empty, the guard behaves exactly
as before.

A fixed set of addresses is refused before the allowlist is
consulted, so no supplied CIDR opens one — not the exact address,
not a supernet, not 0.0.0.0/0 or ::/0. It is the two link-local
blocks (169.254.0.0/16, fe80::/10) plus host routes for the cloud
metadata endpoints that sit outside them: AWS's IPv6 IMDS at
fd00:ec2::254, which lives in ordinary ULA space, and Alibaba's
100.100.100.200, which lives in CGNAT. Allowlisting fd00::/8 or
100.64.0.0/10 (Tailscale's range) is an ordinary thing for an
operator to do and must not reopen instance-credential theft. The
IPv4-compatible (::a9fe:a9fe) and NAT64 (64:ff9b::a9fe:a9fe)
spellings of 169.254.169.254 are listed too, because To4() does not
normalise them into the link-local block the way it does the
IPv4-mapped form. Reaching any of these is credential theft rather
than delivery to an internal service.

The policy now lives in one function, Guard.checkIP, which both
target-creation validation and the delivery dialer call. The two
paths previously decided separately, which is how they came to
disagree about a destination. The guard is built once from config
and injected via fx into both the handlers and the delivery engine,
so there is a single instance and a single answer.

A set-but-unparseable value aborts startup naming the variable,
reusing the existing envPrefixList parser. A non-empty list is
logged at startup with the blocks spelled out, not counted, so the
hole is visible in the log of any deployment that has one.

Tests: an allowlisted loopback CIDR both validates and delivers to a
live server (and the same URL still fails without the allowlist); a
private address outside the listed block stays refused on both
paths; every unconditionally blocked address stays refused on both
paths under an allowlist that covers it, and the set itself is
pinned entry by entry; public addresses are unaffected either way;
and config coverage for parsing, startup abort, and the warning's
contents.
2026-08-20 05:32:09 +00:00

173 lines
3.5 KiB
Go

package delivery_test
import (
"context"
"net"
"testing"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
"sneak.berlin/go/webhooker/internal/delivery"
)
func TestIsBlockedIP_PrivateRanges(t *testing.T) {
t.Parallel()
tests := []struct {
name string
ip string
blocked bool
}{
{"loopback 127.0.0.1", "127.0.0.1", true},
{"loopback 127.0.0.2", "127.0.0.2", true},
{"loopback 127.255.255.255", "127.255.255.255", true},
{"10.0.0.0", "10.0.0.0", true},
{"10.0.0.1", "10.0.0.1", true},
{"10.255.255.255", "10.255.255.255", true},
{"172.16.0.1", "172.16.0.1", true},
{"172.31.255.255", "172.31.255.255", true},
{"172.15.255.255", "172.15.255.255", false},
{"172.32.0.0", "172.32.0.0", false},
{"192.168.0.1", "192.168.0.1", true},
{"192.168.255.255", "192.168.255.255", true},
{"169.254.0.1", "169.254.0.1", true},
{metadataIP, metadataIP, true},
{"8.8.8.8", "8.8.8.8", false},
{"1.1.1.1", "1.1.1.1", false},
{publicIP, publicIP, false},
{"::1", "::1", true},
{"fd00::1", "fd00::1", true},
{"fc00::1", "fc00::1", true},
{"fe80::1", "fe80::1", true},
{
"2607:f8b0:4004:800::200e",
"2607:f8b0:4004:800::200e",
false,
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
t.Parallel()
ip := net.ParseIP(tt.ip)
require.NotNil(t, ip,
"failed to parse IP %s", tt.ip,
)
assert.Equal(t,
tt.blocked,
delivery.ExportIsBlockedIP(ip),
"isBlockedIP(%s) = %v, want %v",
tt.ip,
delivery.ExportIsBlockedIP(ip),
tt.blocked,
)
})
}
}
func TestValidateTargetURL_Blocked(t *testing.T) {
t.Parallel()
blockedURLs := []string{
loopbackHookURL,
"http://127.0.0.1:8080/hook",
"https://10.0.0.1/hook",
"http://192.168.1.1/webhook",
"http://172.16.0.1/api",
metadataURL,
"http://[::1]/hook",
"http://[fc00::1]/hook",
"http://[fe80::1]/hook",
"http://0.0.0.0/hook",
}
for _, u := range blockedURLs {
t.Run(u, func(t *testing.T) {
t.Parallel()
err := delivery.NewTestGuard().ValidateTargetURL(
context.Background(), u,
)
assert.Error(t, err,
"URL %s should be blocked", u,
)
})
}
}
func TestValidateTargetURL_Allowed(t *testing.T) {
t.Parallel()
allowedURLs := []string{
"https://example.com/hook",
"http://93.184.216.34/webhook",
"https://hooks.slack.com/services/T00/B00/xxx",
}
for _, u := range allowedURLs {
t.Run(u, func(t *testing.T) {
t.Parallel()
err := delivery.NewTestGuard().ValidateTargetURL(
context.Background(), u,
)
assert.NoError(t, err,
"URL %s should be allowed", u,
)
})
}
}
func TestValidateTargetURL_InvalidScheme(t *testing.T) {
t.Parallel()
err := delivery.NewTestGuard().ValidateTargetURL(
context.Background(), "ftp://example.com/hook",
)
require.Error(t, err)
assert.Contains(t, err.Error(),
"unsupported URL scheme",
)
}
func TestValidateTargetURL_EmptyHost(t *testing.T) {
t.Parallel()
err := delivery.NewTestGuard().ValidateTargetURL(
context.Background(), "http:///path",
)
assert.Error(t, err)
}
func TestValidateTargetURL_InvalidURL(t *testing.T) {
t.Parallel()
err := delivery.NewTestGuard().ValidateTargetURL(
context.Background(), "://invalid",
)
assert.Error(t, err)
}
func TestBlockedNetworks_Initialized(t *testing.T) {
t.Parallel()
nets := delivery.ExportBlockedNetworks()
assert.NotEmpty(t, nets,
"blockedNetworks should be initialized",
)
assert.GreaterOrEqual(t, len(nets), 8,
"should have at least 8 blocked network ranges",
)
}