From 615a9b8798e6ec58f1b2e1ec08a0f6b3c8cb7f60 Mon Sep 17 00:00:00 2001
From: Tomas Mraz <tomas@openssl.org>
Date: Thu, 18 Nov 2021 20:09:57 +0100
Subject: [PATCH] d2i_PublicKey: Make it work with EC parameters in a provided
 key

Fixes #16989

Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17065)
---
 crypto/asn1/d2i_pu.c | 23 ++++++++++++++++++++---
 test/ectest.c        | 42 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+), 3 deletions(-)

diff --git a/crypto/asn1/d2i_pu.c b/crypto/asn1/d2i_pu.c
index ddf1aad7009..1be114b8a2a 100644
--- a/crypto/asn1/d2i_pu.c
+++ b/crypto/asn1/d2i_pu.c
@@ -29,16 +29,27 @@ EVP_PKEY *d2i_PublicKey(int type, EVP_PKEY **a, const unsigned char **pp,
                         long length)
 {
     EVP_PKEY *ret;
+    EVP_PKEY *copy = NULL;
 
     if ((a == NULL) || (*a == NULL)) {
         if ((ret = EVP_PKEY_new()) == NULL) {
             ERR_raise(ERR_LIB_ASN1, ERR_R_EVP_LIB);
             return NULL;
         }
-    } else
+    } else {
         ret = *a;
 
-    if (type != EVP_PKEY_get_id(ret) && !EVP_PKEY_set_type(ret, type)) {
+#ifndef OPENSSL_NO_EC
+        if (evp_pkey_is_provided(ret)
+            && EVP_PKEY_get_base_id(ret) == EVP_PKEY_EC) {
+            if (!evp_pkey_copy_downgraded(&copy, ret))
+                goto err;
+        }
+#endif
+    }
+
+    if ((type != EVP_PKEY_get_id(ret) || copy != NULL)
+        && !EVP_PKEY_set_type(ret, type)) {
         ERR_raise(ERR_LIB_ASN1, ERR_R_EVP_LIB);
         goto err;
     }
@@ -52,7 +63,6 @@ EVP_PKEY *d2i_PublicKey(int type, EVP_PKEY **a, const unsigned char **pp,
         break;
 #ifndef OPENSSL_NO_DSA
     case EVP_PKEY_DSA:
-        /* TMP UGLY CAST */
         if (!d2i_DSAPublicKey(&ret->pkey.dsa, pp, length)) {
             ERR_raise(ERR_LIB_ASN1, ERR_R_ASN1_LIB);
             goto err;
@@ -61,6 +71,11 @@ EVP_PKEY *d2i_PublicKey(int type, EVP_PKEY **a, const unsigned char **pp,
 #endif
 #ifndef OPENSSL_NO_EC
     case EVP_PKEY_EC:
+        if (copy != NULL) {
+            /* use downgraded parameters from copy */
+            ret->pkey.ec = copy->pkey.ec;
+            copy->pkey.ec = NULL;
+        }
         if (!o2i_ECPublicKey(&ret->pkey.ec, pp, length)) {
             ERR_raise(ERR_LIB_ASN1, ERR_R_ASN1_LIB);
             goto err;
@@ -73,9 +88,11 @@ EVP_PKEY *d2i_PublicKey(int type, EVP_PKEY **a, const unsigned char **pp,
     }
     if (a != NULL)
         (*a) = ret;
+    EVP_PKEY_free(copy);
     return ret;
  err:
     if (a == NULL || *a != ret)
         EVP_PKEY_free(ret);
+    EVP_PKEY_free(copy);
     return NULL;
 }
diff --git a/test/ectest.c b/test/ectest.c
index 30680c742de..8e62cf01e6e 100644
--- a/test/ectest.c
+++ b/test/ectest.c
@@ -2966,6 +2966,47 @@ static int custom_params_test(int id)
     return ret;
 }
 
+static int ec_d2i_publickey_test(void)
+{
+   unsigned char buf[1000];
+   unsigned char *pubkey_enc = buf;
+   const unsigned char *pk_enc = pubkey_enc;
+   EVP_PKEY *gen_key = NULL, *decoded_key = NULL;
+   EVP_PKEY_CTX *pctx = NULL;
+   int pklen, ret = 0;
+   OSSL_PARAM params[2];
+
+   if (!TEST_ptr(gen_key = EVP_EC_gen("P-256")))
+       goto err;
+
+   if (!TEST_int_gt(pklen = i2d_PublicKey(gen_key, &pubkey_enc), 0))
+       goto err;
+
+   params[0] = OSSL_PARAM_construct_utf8_string(OSSL_PKEY_PARAM_GROUP_NAME,
+                                                "P-256", 0);
+   params[1] = OSSL_PARAM_construct_end();
+
+   if (!TEST_ptr(pctx = EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL))
+       || !TEST_true(EVP_PKEY_fromdata_init(pctx))
+       || !TEST_true(EVP_PKEY_fromdata(pctx, &decoded_key,
+                                       OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS,
+                                       params))
+       || !TEST_ptr(decoded_key)
+       || !TEST_ptr(decoded_key = d2i_PublicKey(EVP_PKEY_EC, &decoded_key,
+                                                &pk_enc, pklen)))
+       goto err;
+
+   if (!TEST_true(EVP_PKEY_eq(gen_key, decoded_key)))
+       goto err;
+   ret = 1;
+
+ err:
+   EVP_PKEY_CTX_free(pctx);
+   EVP_PKEY_free(gen_key);
+   EVP_PKEY_free(decoded_key);
+   return ret;
+}
+
 int setup_tests(void)
 {
     crv_len = EC_get_builtin_curves(NULL, 0);
@@ -2993,6 +3034,7 @@ int setup_tests(void)
     ADD_ALL_TESTS(ec_point_hex2point_test, crv_len);
     ADD_ALL_TESTS(custom_generator_test, crv_len);
     ADD_ALL_TESTS(custom_params_test, crv_len);
+    ADD_TEST(ec_d2i_publickey_test);
     return 1;
 }
 
-- 
2.47.2