Factor out PKCS#1 padding

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

diff --git a/gnutls.h b/gnutls.h
index 0e28ed9f95fdf1f37c9ab7cdc64e9f3d665a5fe7..cd79f4098edc08fc4083f89c3b080c56bee9e489 100644 (file)
--- a/gnutls.h
+++ b/gnutls.h
@@ -40,6 +40,8 @@ int tpm2_rsa_sign_hash_fn(gnutls_privkey_t key, gnutls_sign_algorithm_t algo,
 int tpm2_ec_sign_hash_fn(gnutls_privkey_t key, gnutls_sign_algorithm_t algo,
                         void *_vpninfo, unsigned int flags,
                         const gnutls_datum_t *data, gnutls_datum_t *sig);
+int oc_pkcs1_pad(struct openconnect_info *vpninfo,
+                unsigned char *buf, int size, const gnutls_datum_t *data);
 
 /* GnuTLS 3.6.0+ provides this. We have our own for older GnuTLS. There is
  * also _gnutls_encode_ber_rs_raw() in some older versions, but there were

diff --git a/gnutls_tpm2.c b/gnutls_tpm2.c
index e6ed14fb8fc6165e13fe420e1c8463a0e9f12a85..5adc713e466173fc530ac8ab4bacd66eacc99c79 100644 (file)
--- a/gnutls_tpm2.c
+++ b/gnutls_tpm2.c
@@ -342,4 +342,24 @@ int oc_gnutls_encode_rs_value(gnutls_datum_t *sig, const gnutls_datum_t *sig_r,
 }
 #endif /* GnuTLS < 3.6.0 */
 
+/* EMSA-PKCS1-v1_5 padding in accordance with RFC3447 §9.2 */
+#define PKCS1_PAD_OVERHEAD 11
+int oc_pkcs1_pad(struct openconnect_info *vpninfo,
+                unsigned char *buf, int size, const gnutls_datum_t *data)
+{
+       if (data->size + PKCS1_PAD_OVERHEAD > size) {
+               vpn_progress(vpninfo, PRG_ERR,
+                            _("TPM2 digest too large: %d > %d\n"),
+                            data->size, size - PKCS1_PAD_OVERHEAD);
+               return GNUTLS_E_PK_SIGN_FAILED;
+       }
+
+       buf[0] = 0;
+       buf[1] = 1;
+       memset(buf + 2, 0xff, size - data->size - 3);
+       buf[size - data->size - 1] = 0;
+       memcpy(buf + size - data->size, data->data, data->size);
+
+       return 0;
+}
 #endif /* HAVE_TSS2 */

diff --git a/gnutls_tpm2_esys.c b/gnutls_tpm2_esys.c
index 36d36fa874ba791490e4bfbe94ae0fa01a637077..730e624a5e0b69834897949a1cb8fd58a6764c27 100644 (file)
--- a/gnutls_tpm2_esys.c
+++ b/gnutls_tpm2_esys.c
@@ -323,8 +323,6 @@ static int auth_tpm2_key(struct openconnect_info *vpninfo, ESYS_CONTEXT *ctx, ES
        return 0;
 }
 
-#define PKCS1_PAD_OVERHEAD 11
-
 int tpm2_rsa_sign_hash_fn(gnutls_privkey_t key, gnutls_sign_algorithm_t algo,
                          void *_vpninfo, unsigned int flags,
                          const gnutls_datum_t *data, gnutls_datum_t *sig)
@@ -344,19 +342,8 @@ int tpm2_rsa_sign_hash_fn(gnutls_privkey_t key, gnutls_sign_algorithm_t algo,
 
        digest.size = vpninfo->tpm2->pub.publicArea.unique.rsa.size;
 
-       if (data->size + PKCS1_PAD_OVERHEAD > digest.size) {
-               vpn_progress(vpninfo, PRG_ERR,
-                            _("TPM2 digest too large: %d > %d\n"),
-                            data->size, digest.size - PKCS1_PAD_OVERHEAD);
+       if (oc_pkcs1_pad(vpninfo, digest.buffer, digest.size, data))
                return GNUTLS_E_PK_SIGN_FAILED;
-       }
-
-       /* PKCS#1 padding */
-       digest.buffer[0] = 0;
-       digest.buffer[1] = 1;
-       memset(digest.buffer + 2, 0xff, digest.size - data->size - 3);
-       digest.buffer[digest.size - data->size - 1] = 0;
-       memcpy(digest.buffer + digest.size - data->size, data->data, data->size);
 
        if (init_tpm2_key(&ectx, &key_handle, vpninfo))
                goto out;

diff --git a/gnutls_tpm2_ibm.c b/gnutls_tpm2_ibm.c
index a007745752ef8c5b5f205c9e114282dac58dbb13..76a86712eca83e8cae375f7928cce5062bd60904 100644 (file)
--- a/gnutls_tpm2_ibm.c
+++ b/gnutls_tpm2_ibm.c
@@ -355,8 +355,6 @@ static void tpm2_unload_key(TSS_CONTEXT *tssContext, TPM_HANDLE key)
        TSS_Delete(tssContext);
 }
 
-#define PKCS1_PAD_OVERHEAD 11
-
 int tpm2_rsa_sign_hash_fn(gnutls_privkey_t key, gnutls_sign_algorithm_t algo,
                          void *_vpninfo, unsigned int flags,
                          const gnutls_datum_t *data, gnutls_datum_t *sig)
@@ -376,19 +374,8 @@ int tpm2_rsa_sign_hash_fn(gnutls_privkey_t key, gnutls_sign_algorithm_t algo,
 
        in.cipherText.t.size = vpninfo->tpm2->pub.publicArea.unique.rsa.t.size;
 
-       if (data->size + PKCS1_PAD_OVERHEAD > in.cipherText.t.size) {
-               vpn_progress(vpninfo, PRG_ERR,
-                            _("TPM2 digest too large: %d > %d\n"),
-                            data->size, in.cipherText.t.size - PKCS1_PAD_OVERHEAD);
+       if (oc_pkcs1_pad(vpninfo, in.cipherText.t.buffer, in.cipherText.t.size, data))
                return GNUTLS_E_PK_SIGN_FAILED;
-       }
-
-       /* PKCS#1 padding */
-       in.cipherText.t.buffer[0] = 0;
-       in.cipherText.t.buffer[1] = 1;
-       memset(in.cipherText.t.buffer + 2, 0xff, in.cipherText.t.size - data->size - 3);
-       in.cipherText.t.buffer[in.cipherText.t.size - data->size - 1] = 0;
-       memcpy(in.cipherText.t.buffer + in.cipherText.t.size - data->size, data->data, data->size);
 
        in.inScheme.scheme = TPM_ALG_NULL;
        in.keyHandle = tpm2_load_key(vpninfo, &tssContext);