Fix use after free bug that could cause crash when session keys are rotated

Motivation:

Due a bug in our code we could run into a use after free bug when we rotated the session keys while the session key lookup is in process.

Modifications:

- Don't store a reference to a shared pointer

Result:

No more risk of crash

Author: normanmaurer

openssl-dynamic/src/main/c/ssl_private.h

@@ -68,6 +68,7 @@
 #include <openssl/sha.h>
 #if OPENSSL_VERSION_NUMBER >= 0x30000000
 #include <openssl/core_names.h>
+#include <openssl/params.h>
 #endif
 
 #define ERR_LEN 256
@@ -295,9 +296,6 @@ typedef struct tcn_ssl_ctxt_t tcn_ssl_ctxt_t;
 typedef struct {
     unsigned char   key_name[SSL_SESSION_TICKET_KEY_NAME_LEN];
     unsigned char   hmac_key[SSL_SESSION_TICKET_HMAC_KEY_LEN];
-#if OPENSSL_VERSION_NUMBER >= 0x30000000L
-    OSSL_PARAM mac_params[3];
-#endif
     unsigned char   aes_key[SSL_SESSION_TICKET_AES_KEY_LEN];
 } tcn_ssl_ticket_key_t;
 

openssl-dynamic/src/main/c/sslcontext.c

@@ -1332,6 +1332,14 @@ static int find_session_key(tcn_ssl_ctxt_t *c, unsigned char key_name[16], tcn_s
     return result;
 }
 
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+static void fill_mac_params(OSSL_PARAM* params, unsigned char* hmac_key, int hmac_key_length) {
+    params[0] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY, hmac_key, hmac_key_length);
+    params[1] = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_DIGEST, "sha256", 0);
+    params[2] = OSSL_PARAM_construct_end();
+}
+#endif
+
 static int ssl_tlsext_ticket_key_cb(SSL *s,
                                     unsigned char key_name[16],
                                     unsigned char *iv,
@@ -1362,7 +1370,9 @@ static int ssl_tlsext_ticket_key_cb(SSL *s,
 #if OPENSSL_VERSION_NUMBER < 0x30000000L
              HMAC_Init_ex(hmac_ctx, key.hmac_key, 16, EVP_sha256(), NULL);
 #else
-             EVP_MAC_CTX_set_params(mac_ctx, key.mac_params);
+             OSSL_PARAM local_mac_params[3];
+             fill_mac_params(local_mac_params, key.hmac_key, SSL_SESSION_TICKET_HMAC_KEY_LEN);
+             EVP_MAC_CTX_set_params(mac_ctx, local_mac_params);
 #endif
              apr_atomic_inc32(&c->ticket_keys_new);
              return 1;
@@ -1374,7 +1384,9 @@ static int ssl_tlsext_ticket_key_cb(SSL *s,
 #if OPENSSL_VERSION_NUMBER < 0x30000000L
              HMAC_Init_ex(hmac_ctx, key.hmac_key, 16, EVP_sha256(), NULL);
 #else
-             EVP_MAC_CTX_set_params(mac_ctx, key.mac_params);
+             OSSL_PARAM local_mac_params[3];
+             fill_mac_params(local_mac_params, key.hmac_key, SSL_SESSION_TICKET_HMAC_KEY_LEN);
+             EVP_MAC_CTX_set_params(mac_ctx, local_mac_params);
 #endif
              EVP_DecryptInit_ex(ctx, EVP_aes_128_cbc(), NULL, key.aes_key, iv );
              if (!is_current_key) {
@@ -1421,11 +1433,6 @@ TCN_IMPLEMENT_CALL(void, SSLContext, setSessionTicketKeys0)(TCN_STDARGS, jlong c
         key = b + (SSL_SESSION_TICKET_KEY_SIZE * i);
         memcpy(ticket_keys[i].key_name, key, 16);
         memcpy(ticket_keys[i].hmac_key, key + 16, 16);
-#if OPENSSL_VERSION_NUMBER >= 0x30000000L
-        ticket_keys[i].mac_params[0] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY, ticket_keys[i].hmac_key, 16);
-        ticket_keys[i].mac_params[1] = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_DIGEST, "sha256", 0);
-        ticket_keys[i].mac_params[2] = OSSL_PARAM_construct_end();
-#endif
         memcpy(ticket_keys[i].aes_key, key + 32, 16);
     }
     (*e)->ReleaseByteArrayElements(e, keys, b, 0);