Rework eckey_priv_decode()

Factor out the pubkey computation and bring it into more sensible form.
This removes lots of pointless setting of errors (twice) and makes the
code a bit easier on the eyes. Other than that perform some stylistic
cleanup like single exit and add an error check for EVP_PKEY_assign().

ok jsing

1 files changed, 53 insertions, 49 deletions

diff --git a/src/lib/libcrypto/ec/ec_ameth.c b/src/lib/libcrypto/ec/ec_ameth.c
index 245001edfa..2b3b3db63d 100644
--- a/src/lib/libcrypto/ec/ec_ameth.c
+++ b/src/lib/libcrypto/ec/ec_ameth.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ec_ameth.c,v 1.46 2023/12/29 18:45:39 tb Exp $ */
+/* $OpenBSD: ec_ameth.c,v 1.47 2023/12/29 18:46:24 tb Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project 2006.
  */
@@ -302,68 +302,72 @@ eckey_pub_cmp(const EVP_PKEY *a, const EVP_PKEY *b)
 }
 
 static int
+eckey_compute_pubkey(EC_KEY *eckey)
+{
+        const BIGNUM *priv_key;
+        const EC_GROUP *group;
+        EC_POINT *pub_key = NULL;
+        int ret = 0;
+
+        if ((priv_key = EC_KEY_get0_private_key(eckey)) == NULL)
+                goto err;
+        if ((group = EC_KEY_get0_group(eckey)) == NULL)
+                goto err;
+        if ((pub_key = EC_POINT_new(group)) == NULL)
+                goto err;
+        if (!EC_POINT_mul(group, pub_key, priv_key, NULL, NULL, NULL))
+                goto err;
+        if (!EC_KEY_set_public_key(eckey, pub_key))
+                goto err;
+        pub_key = NULL;
+
+        ret = 1;
+
+ err:
+        EC_POINT_free(pub_key);
+
+        return ret;
+}
+
+static int
 eckey_priv_decode(EVP_PKEY *pkey, const PKCS8_PRIV_KEY_INFO *p8)
 {
-        const unsigned char *p = NULL;
+        const unsigned char *priv = NULL;
+        int priv_len;
         const void *pval;
-        int ptype, pklen;
+        int ptype;
         EC_KEY *eckey = NULL;
         const X509_ALGOR *palg;
+        int ret = 0;
 
-        if (!PKCS8_pkey_get0(NULL, &p, &pklen, &palg, p8))
-                return 0;
-        X509_ALGOR_get0(NULL, &ptype, &pval, palg);
+        if (!PKCS8_pkey_get0(NULL, &priv, &priv_len, &palg, p8))
+                goto err;
 
+        X509_ALGOR_get0(NULL, &ptype, &pval, palg);
         if (!eckey_from_params(ptype, pval, &eckey))
-                goto ecliberr;
+                goto err;
 
-        /* We have parameters now set private key */
-        if (!d2i_ECPrivateKey(&eckey, &p, pklen)) {
+        /* Decode private key into eckey. */
+        if (d2i_ECPrivateKey(&eckey, &priv, priv_len) == NULL) {
                 ECerror(EC_R_DECODE_ERROR);
-                goto ecerr;
+                goto err;
         }
-        /* calculate public key (if necessary) */
+        /* If public key was missing from SEC1 key, compute it. */
         if (EC_KEY_get0_public_key(eckey) == NULL) {
-                const BIGNUM *priv_key;
-                const EC_GROUP *group;
-                EC_POINT *pub_key;
-                /*
-                 * the public key was not included in the SEC1 private key =>
-                 * calculate the public key
-                 */
-                group = EC_KEY_get0_group(eckey);
-                pub_key = EC_POINT_new(group);
-                if (pub_key == NULL) {
-                        ECerror(ERR_R_EC_LIB);
-                        goto ecliberr;
-                }
-                if (!EC_POINT_copy(pub_key, EC_GROUP_get0_generator(group))) {
-                        EC_POINT_free(pub_key);
-                        ECerror(ERR_R_EC_LIB);
-                        goto ecliberr;
-                }
-                priv_key = EC_KEY_get0_private_key(eckey);
-                if (!EC_POINT_mul(group, pub_key, priv_key, NULL, NULL, NULL)) {
-                        EC_POINT_free(pub_key);
-                        ECerror(ERR_R_EC_LIB);
-                        goto ecliberr;
-                }
-                if (EC_KEY_set_public_key(eckey, pub_key) == 0) {
-                        EC_POINT_free(pub_key);
-                        ECerror(ERR_R_EC_LIB);
-                        goto ecliberr;
-                }
-                EC_POINT_free(pub_key);
+                if (!eckey_compute_pubkey(eckey))
+                        goto err;
         }
-        EVP_PKEY_assign_EC_KEY(pkey, eckey);
-        return 1;
 
- ecliberr:
-        ECerror(ERR_R_EC_LIB);
- ecerr:
-        if (eckey)
-                EC_KEY_free(eckey);
-        return 0;
+        if (!EVP_PKEY_assign_EC_KEY(pkey, eckey))
+                goto err;
+        eckey = NULL;
+
+        ret = 1;
+
+ err:
+        EC_KEY_free(eckey);
+
+        return ret;
 }
 
 static int