Commit 6718bb22 authored by Filippo Valsorda's avatar Filippo Valsorda

crypto/tls: send a "handshake failure" alert if the RSA key is too small

Fixes #29779

Change-Id: I7eb8b4db187597e07d8ec7d3ff651f008e2ca433
Reviewed-on: https://go-review.googlesource.com/c/158639
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: 's avatarBrad Fitzpatrick <bradfitz@golang.org>
parent a15a0137
......@@ -1697,3 +1697,46 @@ func TestCloneHash(t *testing.T) {
t.Error("cloned hash generated a different sum")
}
}
func TestKeyTooSmallForRSAPSS(t *testing.T) {
clientConn, serverConn := localPipe(t)
client := Client(clientConn, testConfig)
cert, err := X509KeyPair([]byte(`-----BEGIN CERTIFICATE-----
MIIBcTCCARugAwIBAgIQGjQnkCFlUqaFlt6ixyz/tDANBgkqhkiG9w0BAQsFADAS
MRAwDgYDVQQKEwdBY21lIENvMB4XDTE5MDExODIzMjMyOFoXDTIwMDExODIzMjMy
OFowEjEQMA4GA1UEChMHQWNtZSBDbzBcMA0GCSqGSIb3DQEBAQUAA0sAMEgCQQDd
ez1rFUDwax2HTxbcnFUP9AhcgEGMHVV2nn4VVEWFJB6I8C/Nkx0XyyQlrmFYBzEQ
nIPhKls4T0hFoLvjJnXpAgMBAAGjTTBLMA4GA1UdDwEB/wQEAwIFoDATBgNVHSUE
DDAKBggrBgEFBQcDATAMBgNVHRMBAf8EAjAAMBYGA1UdEQQPMA2CC2V4YW1wbGUu
Y29tMA0GCSqGSIb3DQEBCwUAA0EAxDuUS+BrrS3c+h+k+fQPOmOScy6yTX9mHw0Q
KbucGamXYEy0URIwOdO0tQ3LHPc1YGvYSPwkDjkjqECs2Vm/AA==
-----END CERTIFICATE-----`), []byte(`-----BEGIN RSA PRIVATE KEY-----
MIIBOgIBAAJBAN17PWsVQPBrHYdPFtycVQ/0CFyAQYwdVXaefhVURYUkHojwL82T
HRfLJCWuYVgHMRCcg+EqWzhPSEWgu+MmdekCAwEAAQJBALjQYNTdXF4CFBbXwUz/
yt9QFDYT9B5WT/12jeGAe653gtYS6OOi/+eAkGmzg1GlRnw6fOfn+HYNFDORST7z
4j0CIQDn2xz9hVWQEu9ee3vecNT3f60huDGTNoRhtqgweQGX0wIhAPSLj1VcRZEz
nKpbtU22+PbIMSJ+e80fmY9LIPx5N4HTAiAthGSimMR9bloz0EY3GyuUEyqoDgMd
hXxjuno2WesoJQIgemilbcALXpxsLmZLgcQ2KSmaVr7jb5ECx9R+hYKTw1sCIG4s
T+E0J8wlH24pgwQHzy7Ko2qLwn1b5PW8ecrlvP1g
-----END RSA PRIVATE KEY-----`))
if err != nil {
t.Fatal(err)
}
done := make(chan struct{})
go func() {
config := testConfig.Clone()
config.Certificates = []Certificate{cert}
config.MinVersion = VersionTLS13
server := Server(serverConn, config)
err := server.Handshake()
if !strings.Contains(err.Error(), "key size too small for PSS signature") {
t.Errorf(`expected "key size too small for PSS signature", got %q`, err)
}
close(done)
}()
err = client.Handshake()
if !strings.Contains(err.Error(), "handshake failure") {
t.Errorf(`expected "handshake failure", got %q`, err)
}
<-done
}
......@@ -635,7 +635,13 @@ func (hs *serverHandshakeStateTLS13) sendServerCertificate() error {
}
sig, err := hs.cert.PrivateKey.(crypto.Signer).Sign(c.config.rand(), h.Sum(nil), signOpts)
if err != nil {
c.sendAlert(alertInternalError)
public := hs.cert.PrivateKey.(crypto.Signer).Public()
if rsaKey, ok := public.(*rsa.PublicKey); ok && sigType == signatureRSAPSS &&
rsaKey.N.BitLen()/8 < sigHash.Size()*2+2 { // key too small for RSA-PSS
c.sendAlert(alertHandshakeFailure)
} else {
c.sendAlert(alertInternalError)
}
return errors.New("tls: failed to sign handshake: " + err.Error())
}
certVerifyMsg.signature = sig
......
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