Introduce EVP_PKEY_is_opaque to replace RSA_METHOD_FLAG_NO_CHECK.

Custom RSA and ECDSA keys may not expose the key material. Plumb and "opaque"
bit out of the *_METHOD up to EVP_PKEY. Query that in ssl_rsa.c to skip the
sanity checks for certificate and key matching.

Change-Id: I362a2d5116bfd1803560dfca1d69a91153e895fc
Reviewed-on: https://boringssl-review.googlesource.com/1255
Reviewed-by: Adam Langley <agl@google.com>

5 files changed, 24 insertions, 0 deletions

diff --git a/crypto/evp/evp.c b/crypto/evp/evp.c
index 3871859e..06fdabfa 100644
--- a/crypto/evp/evp.c
+++ b/crypto/evp/evp.c
@@ -117,6 +117,13 @@ void EVP_PKEY_free(EVP_PKEY *pkey) {
   OPENSSL_free(pkey);
 }
 
+int EVP_PKEY_is_opaque(const EVP_PKEY *pkey) {
+  if (pkey->ameth && pkey->ameth->pkey_opaque) {
+    return pkey->ameth->pkey_opaque(pkey);
+  }
+  return 0;
+}
+
 int EVP_PKEY_cmp(const EVP_PKEY *a, const EVP_PKEY *b) {
   if (a->type != b->type) {
     return -1;
diff --git a/crypto/evp/internal.h b/crypto/evp/internal.h
index 8561960d..36755f0f 100644
--- a/crypto/evp/internal.h
+++ b/crypto/evp/internal.h
@@ -87,6 +87,10 @@ struct evp_pkey_asn1_method_st {
   int (*priv_print)(BIO *out, const EVP_PKEY *pkey, int indent,
                     ASN1_PCTX *pctx);
 
+  /* pkey_opaque returns 1 if the |pk| is opaque. Opaque keys are backed by
+   * custom implementations which do not expose key material and parameters.*/
+  int (*pkey_opaque)(const EVP_PKEY *pk);
+
   int (*pkey_size)(const EVP_PKEY *pk);
   int (*pkey_bits)(const EVP_PKEY *pk);
 
diff --git a/crypto/evp/p_ec_asn1.c b/crypto/evp/p_ec_asn1.c
index 3038b9ea..fe3ce0ea 100644
--- a/crypto/evp/p_ec_asn1.c
+++ b/crypto/evp/p_ec_asn1.c
@@ -519,6 +519,10 @@ static int eckey_priv_print(BIO *bp, const EVP_PKEY *pkey, int indent,
   return do_EC_KEY_print(bp, pkey->pkey.ec, indent, 2);
 }
 
+static int eckey_opaque(const EVP_PKEY *pkey) {
+  return EC_KEY_is_opaque(pkey->pkey.ec);
+}
+
 static int old_ec_priv_decode(EVP_PKEY *pkey, const uint8_t **pder,
                               int derlen) {
   EC_KEY *ec;
@@ -561,6 +565,8 @@ const EVP_PKEY_ASN1_METHOD ec_asn1_meth = {
   eckey_priv_encode,
   eckey_priv_print,
 
+  eckey_opaque,
+
   int_ec_size,
   ec_bits,
 
diff --git a/crypto/evp/p_hmac_asn1.c b/crypto/evp/p_hmac_asn1.c
index cabd7379..3d5e8017 100644
--- a/crypto/evp/p_hmac_asn1.c
+++ b/crypto/evp/p_hmac_asn1.c
@@ -91,6 +91,7 @@ const EVP_PKEY_ASN1_METHOD hmac_asn1_meth = {
     "HMAC",              "OpenSSL HMAC method", 0 /* pub_decode */,
     0 /* pub_encode */,  0 /* pub_cmp */,       0 /* pub_print */,
     0 /*priv_decode */,  0 /* priv_encode */,   0 /* priv_print */,
+    0 /* pkey_opaque */,
     hmac_size,           0 /* pkey_bits */,     0 /* param_decode */,
     0 /* param_encode*/, 0 /* param_missing*/,  0 /* param_copy*/,
     0 /* param_cmp*/,    0 /* param_print*/,    0 /* sig_print*/,
diff --git a/crypto/evp/p_rsa_asn1.c b/crypto/evp/p_rsa_asn1.c
index f43cdc3a..a9334ab0 100644
--- a/crypto/evp/p_rsa_asn1.c
+++ b/crypto/evp/p_rsa_asn1.c
@@ -149,6 +149,10 @@ static int rsa_priv_decode(EVP_PKEY *pkey, PKCS8_PRIV_KEY_INFO *p8) {
   return 1;
 }
 
+static int rsa_opaque(const EVP_PKEY *pkey) {
+  return RSA_is_opaque(pkey->pkey.rsa);
+}
+
 static int int_rsa_size(const EVP_PKEY *pkey) {
   return RSA_size(pkey->pkey.rsa);
 }
@@ -728,6 +732,8 @@ const EVP_PKEY_ASN1_METHOD rsa_asn1_meth = {
   rsa_priv_encode,
   rsa_priv_print,
 
+  rsa_opaque,
+
   int_rsa_size,
   rsa_bits,