More configurable crypto and ssl library initialization

1.  In addition to overriding the default application name,
    one can now also override the configuration file name
    and flags passed to CONF_modules_load_file().

2.  By default we still keep going when configuration file
    processing fails.  But, applications that want to be
    strict about initialization errors can now make explicit
    flag choices via non-null OPENSSL_INIT_SETTINGS that omit
    the CONF_MFLAGS_IGNORE_RETURN_CODES flag (which had so far
    been both undocumented and unused).

3.  In OPENSSL_init_ssl() do not request OPENSSL_INIT_LOAD_CONFIG
    if the options already include OPENSSL_INIT_NO_LOAD_CONFIG.

4.  Don't set up atexit() handlers when called with opts equal to
    OPENSSL_INIT_BASE_ONLY (this flag should only be used alone).

Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7969)

5 files changed, 84 insertions, 17 deletions

diff --git a/crypto/conf/conf_lib.c b/crypto/conf/conf_lib.c
index 07110d8502..4ae7bd2342 100644
--- a/crypto/conf/conf_lib.c
+++ b/crypto/conf/conf_lib.c
@@ -358,11 +358,36 @@ OPENSSL_INIT_SETTINGS *OPENSSL_INIT_new(void)
 
     if (ret != NULL)
         memset(ret, 0, sizeof(*ret));
+    ret->flags = DEFAULT_CONF_MFLAGS;
+
     return ret;
 }
 
 
 #ifndef OPENSSL_NO_STDIO
+int OPENSSL_INIT_set_config_filename(OPENSSL_INIT_SETTINGS *settings,
+                                     const char *filename)
+{
+    char *newfilename = NULL;
+
+    if (filename != NULL) {
+        newfilename = strdup(filename);
+        if (newfilename == NULL)
+            return 0;
+    }
+
+    free(settings->filename);
+    settings->filename = newfilename;
+
+    return 1;
+}
+
+void OPENSSL_INIT_set_config_file_flags(OPENSSL_INIT_SETTINGS *settings,
+                                        unsigned long flags)
+{
+    settings->flags = flags;
+}
+
 int OPENSSL_INIT_set_config_appname(OPENSSL_INIT_SETTINGS *settings,
                                     const char *appname)
 {
@@ -383,6 +408,7 @@ int OPENSSL_INIT_set_config_appname(OPENSSL_INIT_SETTINGS *settings,
 
 void OPENSSL_INIT_free(OPENSSL_INIT_SETTINGS *settings)
 {
+    free(settings->filename);
     free(settings->appname);
     free(settings);
 }
diff --git a/crypto/conf/conf_mod.c b/crypto/conf/conf_mod.c
index 51f262e774..f1794e2158 100644
--- a/crypto/conf/conf_mod.c
+++ b/crypto/conf/conf_mod.c
@@ -142,6 +142,9 @@ int CONF_modules_load_file(const char *filename, const char *appname,
         OPENSSL_free(file);
     NCONF_free(conf);
 
+    if (flags & CONF_MFLAGS_IGNORE_RETURN_CODES)
+        return 1;
+
     return ret;
 }
 
diff --git a/crypto/conf/conf_sap.c b/crypto/conf/conf_sap.c
index 3d2e065e5b..a3306d02dd 100644
--- a/crypto/conf/conf_sap.c
+++ b/crypto/conf/conf_sap.c
@@ -39,10 +39,24 @@ void OPENSSL_config(const char *appname)
 }
 #endif
 
-void openssl_config_int(const char *appname)
+int openssl_config_int(const OPENSSL_INIT_SETTINGS *settings)
 {
+    int ret;
+    const char *filename;
+    const char *appname;
+    unsigned long flags;
+
     if (openssl_configured)
-        return;
+        return 1;
+
+    filename = settings ? settings->filename : NULL;
+    appname = settings ? settings->appname : NULL;
+    flags = settings ? settings->flags : DEFAULT_CONF_MFLAGS;
+
+#ifdef OPENSSL_INIT_DEBUG
+    fprintf(stderr, "OPENSSL_INIT: openssl_config_int(%s, %s, %lu)\n",
+            filename, appname, flags);
+#endif
 
     OPENSSL_load_builtin_modules();
 #ifndef OPENSSL_NO_ENGINE
@@ -51,11 +65,10 @@ void openssl_config_int(const char *appname)
 #endif
     ERR_clear_error();
 #ifndef OPENSSL_SYS_UEFI
-    CONF_modules_load_file(NULL, appname,
-                               CONF_MFLAGS_DEFAULT_SECTION |
-                               CONF_MFLAGS_IGNORE_MISSING_FILE);
+    ret = CONF_modules_load_file(filename, appname, flags);
 #endif
     openssl_configured = 1;
+    return ret;
 }
 
 void openssl_no_config_int(void)
diff --git a/crypto/err/err.c b/crypto/err/err.c
index aef2543d60..7bac6776c8 100644
--- a/crypto/err/err.c
+++ b/crypto/err/err.c
@@ -741,6 +741,18 @@ int err_shelve_state(void **state)
 {
     int saveerrno = get_last_sys_error();
 
+    /*
+     * Note, at present our only caller is OPENSSL_init_crypto(), indirectly
+     * via ossl_init_load_crypto_nodelete(), by which point the requested
+     * "base" initialization has already been performed, so the below call is a
+     * NOOP, that re-enters OPENSSL_init_crypto() only to quickly return.
+     *
+     * If are no other valid callers of this function, the call below can be
+     * removed, avoiding the re-entry into OPENSSL_init_crypto().  If there are
+     * potential uses that are not from inside OPENSSL_init_crypto(), then this
+     * call is needed, but some care is required to make sure that the re-entry
+     * remains a NOOP.
+     */
     if (!OPENSSL_init_crypto(OPENSSL_INIT_BASE_ONLY, NULL))
         return 0;
 
diff --git a/crypto/init.c b/crypto/init.c
index 46ba67d3e4..c881fc7382 100644
--- a/crypto/init.c
+++ b/crypto/init.c
@@ -288,17 +288,12 @@ DEFINE_RUN_ONCE_STATIC_ALT(ossl_init_no_add_all_digests,
 
 static CRYPTO_ONCE config = CRYPTO_ONCE_STATIC_INIT;
 static int config_inited = 0;
-static const char *appname;
+static const OPENSSL_INIT_SETTINGS *conf_settings = NULL;
 DEFINE_RUN_ONCE_STATIC(ossl_init_config)
 {
-#ifdef OPENSSL_INIT_DEBUG
-    fprintf(stderr,
-            "OPENSSL_INIT: ossl_init_config: openssl_config(%s)\n",
-            appname == NULL ? "NULL" : appname);
-#endif
-    openssl_config_int(appname);
+    int ret = openssl_config_int(conf_settings);
     config_inited = 1;
-    return 1;
+    return ret;
 }
 DEFINE_RUN_ONCE_STATIC_ALT(ossl_init_no_config, ossl_init_config)
 {
@@ -631,9 +626,28 @@ int OPENSSL_init_crypto(uint64_t opts, const OPENSSL_INIT_SETTINGS *settings)
         return 0;
     }
 
+    /*
+     * When the caller specifies OPENSSL_INIT_BASE_ONLY, that should be the
+     * *only* option specified.  With that option we return immediately after
+     * doing the requested limited initialization.  Note that
+     * err_shelve_state() called by us via ossl_init_load_crypto_nodelete()
+     * re-enters OPENSSL_init_crypto() with OPENSSL_INIT_BASE_ONLY, but with
+     * base already initialized this is a harmless NOOP.
+     *
+     * If we remain the only caller of err_shelve_state() the recursion should
+     * perhaps be removed, but if in doubt, it can be left in place.
+     */
     if (!RUN_ONCE(&base, ossl_init_base))
         return 0;
+    if (opts & OPENSSL_INIT_BASE_ONLY)
+        return 1;
 
+    /*
+     * Now we don't always set up exit handlers, the INIT_BASE_ONLY calls
+     * should not have the side-effect of setting up exit handlers, and
+     * therefore, this code block is below the INIT_BASE_ONLY-conditioned early
+     * return above.
+     */
     if ((opts & OPENSSL_INIT_NO_ATEXIT) != 0) {
         if (!RUN_ONCE_ALT(&register_atexit, ossl_init_no_register_atexit,
                           ossl_init_register_atexit))
@@ -642,9 +656,7 @@ int OPENSSL_init_crypto(uint64_t opts, const OPENSSL_INIT_SETTINGS *settings)
         return 0;
     }
 
-    if (!(opts & OPENSSL_INIT_BASE_ONLY)
-            && !RUN_ONCE(&load_crypto_nodelete,
-                         ossl_init_load_crypto_nodelete))
+    if (!RUN_ONCE(&load_crypto_nodelete, ossl_init_load_crypto_nodelete))
         return 0;
 
     if ((opts & OPENSSL_INIT_NO_LOAD_CRYPTO_STRINGS)
@@ -686,8 +698,9 @@ int OPENSSL_init_crypto(uint64_t opts, const OPENSSL_INIT_SETTINGS *settings)
     if (opts & OPENSSL_INIT_LOAD_CONFIG) {
         int ret;
         CRYPTO_THREAD_write_lock(init_lock);
-        appname = (settings == NULL) ? NULL : settings->appname;
+        conf_settings = settings;
         ret = RUN_ONCE(&config, ossl_init_config);
+        conf_settings = NULL;
         CRYPTO_THREAD_unlock(init_lock);
         if (!ret)
             return 0;