Restore the meaning of EVP_PKEY_print_private()

With pre-3.0 OpenSSL, EVP_PKEY_print_private() calls the EVP_PKEY_ASN1_METHOD
function "priv_print", effectively asking the backend to print whatever it
regards as private key components.

In all backends that were built into libcrypto, this function printed what
was included in the private key structure, which usually includes the
public key components as well.

With OpenSSL 3.0, some of the corresponding key2text encoders got a
slightly different behavior, where the presence of the selector
OSSL_KEYMGMT_SELECT_PRIVATE_KEY without the presence of the selector
OSSL_KEYMGMT_SELECT_PUBLIC_KEY would only get what would intuitively be
regarded as private key components printed.  This isn't entirely consistent,
though, as the RSA key2text encoder will still print the public key
components regardless.

To compensate for the changed backend behavior, EVP_PKEY_print_private()
was made to ask the encoder to print the keypair rather than just the
private key, thereby moving the backend semantics to the application API.
Unfortunately, this causes confusion for providers where the key2text
encoder really should print the private key only.

This change restores the built-in 1.1.1 backend behavior in the encoders
that OpenSSL provides, and renders EVP_PKEY_print_private() more true to its
documented behavior, leaving it to the backend to decide what it regards as
"private key components".

Fixes #22233

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22237)

(cherry picked from commit 1296c2ec7866a4f2f4d210432c771142e8de33a0)

3 files changed, 28 insertions, 39 deletions

diff --git a/crypto/evp/p_lib.c b/crypto/evp/p_lib.c
index 59a7a867ec..04b148a912 100644
--- a/crypto/evp/p_lib.c
+++ b/crypto/evp/p_lib.c
@@ -1201,7 +1201,7 @@ int EVP_PKEY_print_public(BIO *out, const EVP_PKEY *pkey,
 int EVP_PKEY_print_private(BIO *out, const EVP_PKEY *pkey,
                            int indent, ASN1_PCTX *pctx)
 {
-    return print_pkey(pkey, out, indent, EVP_PKEY_KEYPAIR, NULL,
+    return print_pkey(pkey, out, indent, EVP_PKEY_PRIVATE_KEY, NULL,
                       (pkey->ameth != NULL ? pkey->ameth->priv_print : NULL),
                       pctx);
 }
diff --git a/include/openssl/evp.h b/include/openssl/evp.h
index 49e8e1df78..22e8c25098 100644
--- a/include/openssl/evp.h
+++ b/include/openssl/evp.h
@@ -85,6 +85,8 @@
 /* Easy to use macros for EVP_PKEY related selections */
 # define EVP_PKEY_KEY_PARAMETERS                                            \
     ( OSSL_KEYMGMT_SELECT_ALL_PARAMETERS )
+# define EVP_PKEY_PRIVATE_KEY                                               \
+    ( EVP_PKEY_KEY_PARAMETERS | OSSL_KEYMGMT_SELECT_PRIVATE_KEY )
 # define EVP_PKEY_PUBLIC_KEY                                                \
     ( EVP_PKEY_KEY_PARAMETERS | OSSL_KEYMGMT_SELECT_PUBLIC_KEY )
 # define EVP_PKEY_KEYPAIR                                                   \
diff --git a/providers/implementations/encode_decode/encode_key2text.c b/providers/implementations/encode_decode/encode_key2text.c
index 7d983f5e51..9ec3490c3a 100644
--- a/providers/implementations/encode_decode/encode_key2text.c
+++ b/providers/implementations/encode_decode/encode_key2text.c
@@ -241,7 +241,7 @@ static int dh_to_text(BIO *out, const void *key, int selection)
             return 0;
         }
     }
-    if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0) {
+    if ((selection & OSSL_KEYMGMT_SELECT_KEYPAIR) != 0) {
         pub_key = DH_get0_pub_key(dh);
         if (pub_key == NULL) {
             ERR_raise(ERR_LIB_PROV, PROV_R_NOT_A_PUBLIC_KEY);
@@ -316,7 +316,7 @@ static int dsa_to_text(BIO *out, const void *key, int selection)
             return 0;
         }
     }
-    if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0) {
+    if ((selection & OSSL_KEYMGMT_SELECT_KEYPAIR) != 0) {
         pub_key = DSA_get0_pub_key(dsa);
         if (pub_key == NULL) {
             ERR_raise(ERR_LIB_PROV, PROV_R_NOT_A_PUBLIC_KEY);
@@ -525,7 +525,7 @@ static int ec_to_text(BIO *out, const void *key, int selection)
         if (priv_len == 0)
             goto err;
     }
-    if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0) {
+    if ((selection & OSSL_KEYMGMT_SELECT_KEYPAIR) != 0) {
         const EC_POINT *pub_pt = EC_KEY_get0_public_key(ec);
 
         if (pub_pt == NULL) {
@@ -575,26 +575,31 @@ static int ecx_to_text(BIO *out, const void *key, int selection)
         return 0;
     }
 
+    switch (ecx->type) {
+    case ECX_KEY_TYPE_X25519:
+        type_label = "X25519";
+        break;
+    case ECX_KEY_TYPE_X448:
+        type_label = "X448";
+        break;
+    case ECX_KEY_TYPE_ED25519:
+        type_label = "ED25519";
+        break;
+    case ECX_KEY_TYPE_ED448:
+        type_label = "ED448";
+        break;
+    }
+
     if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0) {
         if (ecx->privkey == NULL) {
             ERR_raise(ERR_LIB_PROV, PROV_R_NOT_A_PRIVATE_KEY);
             return 0;
         }
 
-        switch (ecx->type) {
-        case ECX_KEY_TYPE_X25519:
-            type_label = "X25519 Private-Key";
-            break;
-        case ECX_KEY_TYPE_X448:
-            type_label = "X448 Private-Key";
-            break;
-        case ECX_KEY_TYPE_ED25519:
-            type_label = "ED25519 Private-Key";
-            break;
-        case ECX_KEY_TYPE_ED448:
-            type_label = "ED448 Private-Key";
-            break;
-        }
+        if (BIO_printf(out, "%s Private-Key:\n", type_label) <= 0)
+            return 0;
+        if (!print_labeled_buf(out, "priv:", ecx->privkey, ecx->keylen))
+            return 0;
     } else if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0) {
         /* ecx->pubkey is an array, not a pointer... */
         if (!ecx->haspubkey) {
@@ -602,29 +607,11 @@ static int ecx_to_text(BIO *out, const void *key, int selection)
             return 0;
         }
 
-        switch (ecx->type) {
-        case ECX_KEY_TYPE_X25519:
-            type_label = "X25519 Public-Key";
-            break;
-        case ECX_KEY_TYPE_X448:
-            type_label = "X448 Public-Key";
-            break;
-        case ECX_KEY_TYPE_ED25519:
-            type_label = "ED25519 Public-Key";
-            break;
-        case ECX_KEY_TYPE_ED448:
-            type_label = "ED448 Public-Key";
-            break;
-        }
+        if (BIO_printf(out, "%s Public-Key:\n", type_label) <= 0)
+            return 0;
     }
 
-    if (BIO_printf(out, "%s:\n", type_label) <= 0)
-        return 0;
-    if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0
-        && !print_labeled_buf(out, "priv:", ecx->privkey, ecx->keylen))
-        return 0;
-    if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0
-        && !print_labeled_buf(out, "pub:", ecx->pubkey, ecx->keylen))
+    if (!print_labeled_buf(out, "pub:", ecx->pubkey, ecx->keylen))
         return 0;
 
     return 1;