ipn/ipnlocal: use ACME ALPN for authorized Funnel non-CertDomain domains

If a user explicitly adds a non-ts.net (not a CertDomain domain) domain
like "foo.com" to their serve config as a web target that's also an allowed
funnel domain (using raw "tailscale serve set-config"), then use the new
ALPN cert fetching (from b553969b) to get certs for that domain.

This is just plumbing; there's no new product functionality to
actually enable this easily client-side, and it also has no visible
product surface to enable it server-side.

Updates tailscale/corp#41736

Change-Id: Ie2e421ac9611bce64bba3de6a454b2d505ea0e8a
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick 2026-05-28 19:16:42 +00:00 committed by Brad Fitzpatrick
parent 788a49eca5
commit 412c812d76
2 changed files with 236 additions and 17 deletions

View File

@ -168,8 +168,13 @@ func (b *LocalBackend) GetCertPEM(ctx context.Context, domain string) (*TLSCertK
//
// - An exact CertDomain (e.g., "node.ts.net")
// - A wildcard domain (e.g., "*.node.ts.net")
// - A bring-your-own Funnel domain referenced by the local serve config
// (e.g., "foo.com" when ServeConfig.AllowFunnel has "foo.com:443").
//
// The wildcard format requires the NodeAttrDNSSubdomainResolve capability.
// ts.net domains are issued via dns-01 against control's DNS zone; BYO
// Funnel domains are issued via tls-alpn-01 over the same Funnel TLS path
// that serves real traffic.
func (b *LocalBackend) GetCertPEMWithValidity(ctx context.Context, domain string, minValidity time.Duration) (*TLSCertKeyPair, error) {
b.mu.Lock()
getCertForTest := b.getCertForTest
@ -311,6 +316,13 @@ func (b *LocalBackend) shouldUseACMETLSALPN01(domain string, previous *TLSCertKe
logf("acme: using dns-01: Funnel is not enabled for %s:443", domain)
return false
}
if b.isBYOFunnelDomain(domain) {
// BYO Funnel domain: dns-01 is not a viable path because control
// does not own the user's DNS zone. Use tls-alpn-01 even on
// first issuance.
logf("acme: using tls-alpn-01 (BYO Funnel domain)")
return true
}
if previous == nil {
logf("acme: using dns-01: no cached certificate for Funnel renewal")
return false
@ -319,6 +331,22 @@ func (b *LocalBackend) shouldUseACMETLSALPN01(domain string, previous *TLSCertKe
return true
}
// isBYOFunnelDomain reports whether domain is a "bring your own" Funnel
// hostname: a domain that is not in the netmap's CertDomains but is
// referenced as a Funnel target on :443 by the local serve config.
// BYO domains can only be issued via tls-alpn-01 because control does
// not own their DNS zone.
func (b *LocalBackend) isBYOFunnelDomain(domain string) bool {
if domain == "" || isWildcardDomain(domain) {
return false
}
nm := b.NetMapNoPeers()
if nm != nil && slices.Contains(nm.DNS.CertDomains, domain) {
return false
}
return b.hasFunnelForHostPort(domain, 443)
}
func challengeByType(challenges []*acme.Challenge, typ string) *acme.Challenge {
for _, ch := range challenges {
if ch.Type == typ {
@ -695,6 +723,12 @@ func getCertPEMCached(cs certStore, domain string, now time.Time) (p *TLSCertKey
if ctx.Err() != nil {
return nil, ctx.Err()
}
if b.isBYOFunnelDomain(domain) {
// BYO domains have no working dns-01 path (control does not
// own the zone), so surface the tls-alpn-01 error instead of
// burning an ACME attempt on a guaranteed-to-fail fallback.
return nil, err
}
logf("acme: tls-alpn-01 failed; falling back to dns-01: %v", err)
}
issueArgs.challengeType = acmeChallengeDNS01
@ -1077,6 +1111,8 @@ func validLookingCertDomain(name string) bool {
//
// - "node.ts.net" -> "node.ts.net" (exact CertDomain match)
// - "*.node.ts.net" -> "*.node.ts.net" (explicit wildcard, requires NodeAttrDNSSubdomainResolve)
// - "foo.com" -> "foo.com" (bring-your-own Funnel domain referenced by the
// local serve config; issued via tls-alpn-01 in getCertPEM)
//
// Subdomain requests like "app.node.ts.net" are rejected; callers should
// request "*.node.ts.net" explicitly for subdomain coverage.
@ -1091,7 +1127,7 @@ func (b *LocalBackend) resolveCertDomain(domain string) (string, error) {
return "", errors.New("no netmap available")
}
certDomains := nm.DNS.CertDomains
if len(certDomains) == 0 {
if len(certDomains) == 0 && !b.isBYOFunnelDomain(domain) {
return "", errors.New("your Tailscale account does not support getting TLS certs")
}
@ -1111,6 +1147,13 @@ func (b *LocalBackend) resolveCertDomain(domain string) (string, error) {
return domain, nil
}
// Bring-your-own Funnel domain (e.g. "foo.com"). The serve config
// references the domain as a Funnel target on :443; cert acquisition
// happens via tls-alpn-01 in getCertPEM.
if b.isBYOFunnelDomain(domain) {
return domain, nil
}
return "", fmt.Errorf("invalid domain %q; must be one of %q", domain, certDomains)
}

View File

@ -305,32 +305,208 @@ func TestServeTLSConfigNextProtos(t *testing.T) {
}
func TestShouldUseACMETLSALPN01(t *testing.T) {
const domain = "example.com"
const (
tsNetDomain = "node.ts.net"
byoDomain = "foo.com"
)
previous := &TLSCertKeyPair{}
setFunnel := func(b *LocalBackend, hosts ...string) {
funnel := map[ipn.HostPort]bool{}
for _, h := range hosts {
funnel[ipn.HostPort(h+":443")] = true
}
b.mu.Lock()
b.serveConfig = (&ipn.ServeConfig{AllowFunnel: funnel}).View()
b.mu.Unlock()
}
setNetmap := func(b *LocalBackend, certDomains ...string) {
b.mu.Lock()
b.currentNode().SetNetMap(&netmap.NetworkMap{
SelfNode: (&tailcfg.Node{}).View(),
DNS: tailcfg.DNSConfig{CertDomains: certDomains},
})
b.mu.Unlock()
}
tests := []struct {
name string
domain string
previous *TLSCertKeyPair
funnel []string
netmap []string // CertDomains; if nil, no netmap installed
want bool
}{
{
name: "tsnet_renewal",
domain: tsNetDomain,
previous: previous,
funnel: []string{tsNetDomain},
netmap: []string{tsNetDomain},
want: true,
},
{
name: "tsnet_first_issuance_prefers_dns01",
domain: tsNetDomain,
previous: nil,
funnel: []string{tsNetDomain},
netmap: []string{tsNetDomain},
want: false,
},
{
name: "tsnet_wildcard_rejected",
domain: "*." + tsNetDomain,
previous: previous,
funnel: []string{tsNetDomain},
netmap: []string{tsNetDomain},
want: false,
},
{
name: "tsnet_without_funnel_rejected",
domain: tsNetDomain,
previous: previous,
funnel: nil,
netmap: []string{tsNetDomain},
want: false,
},
{
name: "byo_first_issuance_uses_alpn",
domain: byoDomain,
previous: nil,
funnel: []string{byoDomain},
netmap: []string{tsNetDomain},
want: true,
},
{
name: "byo_renewal_uses_alpn",
domain: byoDomain,
previous: previous,
funnel: []string{byoDomain},
netmap: []string{tsNetDomain},
want: true,
},
{
name: "byo_without_funnel_rejected",
domain: byoDomain,
previous: previous,
funnel: nil,
netmap: []string{tsNetDomain},
want: false,
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
b := newTestLocalBackend(t)
if tt.netmap != nil {
setNetmap(b, tt.netmap...)
}
setFunnel(b, tt.funnel...)
if got := b.shouldUseACMETLSALPN01(tt.domain, tt.previous, t.Logf); got != tt.want {
t.Errorf("shouldUseACMETLSALPN01(%q, previous=%v) = %v, want %v",
tt.domain, tt.previous != nil, got, tt.want)
}
})
}
}
func TestIsBYOFunnelDomain(t *testing.T) {
setFunnel := func(b *LocalBackend, hosts ...string) {
funnel := map[ipn.HostPort]bool{}
for _, h := range hosts {
funnel[ipn.HostPort(h+":443")] = true
}
b.mu.Lock()
b.serveConfig = (&ipn.ServeConfig{AllowFunnel: funnel}).View()
b.mu.Unlock()
}
setNetmap := func(b *LocalBackend, certDomains ...string) {
b.mu.Lock()
b.currentNode().SetNetMap(&netmap.NetworkMap{
SelfNode: (&tailcfg.Node{}).View(),
DNS: tailcfg.DNSConfig{CertDomains: certDomains},
})
b.mu.Unlock()
}
tests := []struct {
name string
domain string
certDomains []string
funnel []string
want bool
}{
{name: "byo_with_funnel", domain: "foo.com", certDomains: []string{"node.ts.net"}, funnel: []string{"foo.com"}, want: true},
{name: "byo_without_funnel", domain: "foo.com", certDomains: []string{"node.ts.net"}, want: false},
{name: "tsnet_exact_match_not_byo", domain: "node.ts.net", certDomains: []string{"node.ts.net"}, funnel: []string{"node.ts.net"}, want: false},
{name: "wildcard_never_byo", domain: "*.foo.com", certDomains: []string{"node.ts.net"}, funnel: []string{"foo.com"}, want: false},
{name: "empty_never_byo", domain: "", certDomains: []string{"node.ts.net"}, funnel: []string{"foo.com"}, want: false},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
b := newTestLocalBackend(t)
setNetmap(b, tt.certDomains...)
setFunnel(b, tt.funnel...)
if got := b.isBYOFunnelDomain(tt.domain); got != tt.want {
t.Errorf("isBYOFunnelDomain(%q) = %v, want %v", tt.domain, got, tt.want)
}
})
}
}
func TestResolveCertDomainBYO(t *testing.T) {
const (
tsNetDomain = "node.ts.net"
byoDomain = "foo.com"
)
b := newTestLocalBackend(t)
b.mu.Lock()
b.currentNode().SetNetMap(&netmap.NetworkMap{
SelfNode: (&tailcfg.Node{}).View(),
DNS: tailcfg.DNSConfig{CertDomains: []string{tsNetDomain}},
})
b.mu.Unlock()
// Without a serve config, BYO is rejected.
if _, err := b.resolveCertDomain(byoDomain); err == nil {
t.Fatalf("resolveCertDomain(%q) without serve config: want error, got nil", byoDomain)
}
// Web entry alone (no AllowFunnel) is not enough; the gate is Funnel.
b.mu.Lock()
b.serveConfig = (&ipn.ServeConfig{
AllowFunnel: map[ipn.HostPort]bool{
domain + ":443": true,
Web: map[ipn.HostPort]*ipn.WebServerConfig{
byoDomain + ":443": {Handlers: map[string]*ipn.HTTPHandler{"/": {Proxy: "http://127.0.0.1:8080"}}},
},
}).View()
b.mu.Unlock()
previous := &TLSCertKeyPair{}
if !b.shouldUseACMETLSALPN01(domain, previous, t.Logf) {
t.Fatal("shouldUseACMETLSALPN01 = false, want true")
}
if b.shouldUseACMETLSALPN01(domain, nil, t.Logf) {
t.Fatal("shouldUseACMETLSALPN01 without cached cert = true, want false")
}
if b.shouldUseACMETLSALPN01("*."+domain, previous, t.Logf) {
t.Fatal("shouldUseACMETLSALPN01 for wildcard = true, want false")
if _, err := b.resolveCertDomain(byoDomain); err == nil {
t.Fatalf("resolveCertDomain(%q) with Web but no Funnel: want error, got nil", byoDomain)
}
// With AllowFunnel, BYO is accepted.
b.mu.Lock()
b.serveConfig = (&ipn.ServeConfig{}).View()
b.serveConfig = (&ipn.ServeConfig{
Web: map[ipn.HostPort]*ipn.WebServerConfig{
byoDomain + ":443": {Handlers: map[string]*ipn.HTTPHandler{"/": {Proxy: "http://127.0.0.1:8080"}}},
},
AllowFunnel: map[ipn.HostPort]bool{byoDomain + ":443": true},
}).View()
b.mu.Unlock()
if b.shouldUseACMETLSALPN01(domain, previous, t.Logf) {
t.Fatal("shouldUseACMETLSALPN01 without Funnel = true, want false")
got, err := b.resolveCertDomain(byoDomain)
if err != nil {
t.Fatalf("resolveCertDomain(%q): %v", byoDomain, err)
}
if got != byoDomain {
t.Errorf("resolveCertDomain(%q) = %q, want %q", byoDomain, got, byoDomain)
}
// The ts.net path still works alongside BYO entries.
got, err = b.resolveCertDomain(tsNetDomain)
if err != nil {
t.Fatalf("resolveCertDomain(%q): %v", tsNetDomain, err)
}
if got != tsNetDomain {
t.Errorf("resolveCertDomain(%q) = %q, want %q", tsNetDomain, got, tsNetDomain)
}
}