Prepare to provide EVP_PKEY_new_CMAC_key()

sebastia ran into this when attempting to update security/hcxtools.
This will be tested via wycheproof.go once the symbol is public.

ok jsing, tested by sebastia

1 files changed, 43 insertions, 8 deletions

diff --git a/src/lib/libcrypto/evp/p_lib.c b/src/lib/libcrypto/evp/p_lib.c
index 13a9d65f28..9577b10ea1 100644
--- a/src/lib/libcrypto/evp/p_lib.c
+++ b/src/lib/libcrypto/evp/p_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: p_lib.c,v 1.25 2019/03/17 18:17:45 tb Exp $ */
+/* $OpenBSD: p_lib.c,v 1.26 2021/03/29 15:57:23 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -61,6 +61,7 @@
 #include <openssl/opensslconf.h>
 
 #include <openssl/bn.h>
+#include <openssl/cmac.h>
 #include <openssl/err.h>
 #include <openssl/evp.h>
 #include <openssl/objects.h>
@@ -216,10 +217,14 @@ EVP_PKEY_up_ref(EVP_PKEY *pkey)
  */
 
 static int
-pkey_set_type(EVP_PKEY *pkey, int type, const char *str, int len)
+pkey_set_type(EVP_PKEY *pkey, ENGINE *e, int type, const char *str, int len)
 {
         const EVP_PKEY_ASN1_METHOD *ameth;
-        ENGINE *e = NULL;
+        ENGINE **eptr = NULL;
+
+        if (e == NULL)
+                eptr = &e;
+
         if (pkey) {
                 if (pkey->pkey.ptr)
                         EVP_PKEY_free_it(pkey);
@@ -234,11 +239,11 @@ pkey_set_type(EVP_PKEY *pkey, int type, const char *str, int len)
 #endif
         }
         if (str)
-                ameth = EVP_PKEY_asn1_find_str(&e, str, len);
+                ameth = EVP_PKEY_asn1_find_str(eptr, str, len);
         else
-                ameth = EVP_PKEY_asn1_find(&e, type);
+                ameth = EVP_PKEY_asn1_find(eptr, type);
 #ifndef OPENSSL_NO_ENGINE
-        if (pkey == NULL)
+        if (pkey == NULL && eptr != NULL)
                 ENGINE_finish(e);
 #endif
         if (!ameth) {
@@ -258,13 +263,43 @@ pkey_set_type(EVP_PKEY *pkey, int type, const char *str, int len)
 int
 EVP_PKEY_set_type(EVP_PKEY *pkey, int type)
 {
-        return pkey_set_type(pkey, type, NULL, -1);
+        return pkey_set_type(pkey, NULL, type, NULL, -1);
+}
+
+EVP_PKEY *
+EVP_PKEY_new_CMAC_key(ENGINE *e, const unsigned char *priv, size_t len,
+    const EVP_CIPHER *cipher)
+{
+        EVP_PKEY *ret = NULL;
+        CMAC_CTX *cmctx = NULL;
+
+        if ((ret = EVP_PKEY_new()) == NULL)
+                goto err;
+        if ((cmctx = CMAC_CTX_new()) == NULL)
+                goto err;
+
+        if (!pkey_set_type(ret, e, EVP_PKEY_CMAC, NULL, -1))
+                goto err;
+
+        if (!CMAC_Init(cmctx, priv, len, cipher, e)) {
+                EVPerror(EVP_R_KEY_SETUP_FAILED);
+                goto err;
+        }
+
+        ret->pkey.ptr = (char *)cmctx;
+
+        return ret;
+
+ err:
+        EVP_PKEY_free(ret);
+        CMAC_CTX_free(cmctx);
+        return NULL;
 }
 
 int
 EVP_PKEY_set_type_str(EVP_PKEY *pkey, const char *str, int len)
 {
-        return pkey_set_type(pkey, EVP_PKEY_NONE, str, len);
+        return pkey_set_type(pkey, NULL, EVP_PKEY_NONE, str, len);
 }
 
 int