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 INIT_BASE_ONLY.

Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7986)

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);
 }

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;
 }
 

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)

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;
 

crypto/init.c

@@ -311,17 +311,12 @@ DEFINE_RUN_ONCE_STATIC_ALT(ossl_init_no_add_all_macs, ossl_init_add_all_macs)
 
 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)
 {
@@ -654,9 +649,29 @@ 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))
@@ -665,9 +680,7 @@ 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)
@@ -718,8 +731,9 @@ 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;

doc/man3/CONF_modules_load_file.pod

@@ -28,13 +28,21 @@ reads configuration information from B<cnf>.
 
 The following B<flags> are currently recognized:
 
-B<CONF_MFLAGS_IGNORE_ERRORS> if set errors returned by individual
+If B<CONF_MFLAGS_IGNORE_ERRORS> is set errors returned by individual
 configuration modules are ignored. If not set the first module error is
 considered fatal and no further modules are loaded.
 
 Normally any modules errors will add error information to the error queue. If
 B<CONF_MFLAGS_SILENT> is set no error information is added.
 
+If B<CONF_MFLAGS_IGNORE_RETURN_CODES> is set the function unconditionally
+returns success.
+This is used by default in L<OPENSSL_init_crypto(3)> to ignore any errors in
+the default system-wide configuration file, as having all OpenSSL applications
+fail to start when there are potentially minor issues in the file is too risky.
+Applications calling B<CONF_modules_load_file> explicitly should not generally
+set this flag.
+
 If B<CONF_MFLAGS_NO_DSO> is set configuration module loading from DSOs is
 disabled.
 

doc/man3/OPENSSL_init_crypto.pod

@@ -2,10 +2,11 @@
 
 =head1 NAME
 
-OPENSSL_INIT_new, OPENSSL_INIT_set_config_appname, OPENSSL_INIT_free,
-OPENSSL_init_crypto, OPENSSL_cleanup,
-OPENSSL_atexit, OPENSSL_thread_stop - OpenSSL
-initialisation and deinitialisation functions
+OPENSSL_INIT_new, OPENSSL_INIT_set_config_filename,
+OPENSSL_INIT_set_config_appname, OPENSSL_INIT_set_config_file_flags,
+OPENSSL_INIT_free, OPENSSL_init_crypto, OPENSSL_cleanup, OPENSSL_atexit,
+OPENSSL_thread_stop - OpenSSL initialisation
+and deinitialisation functions
 
 =head1 SYNOPSIS
 
@@ -17,6 +18,10 @@ initialisation and deinitialisation functions
  void OPENSSL_thread_stop(void);
 
  OPENSSL_INIT_SETTINGS *OPENSSL_INIT_new(void);
+ int OPENSSL_INIT_set_config_filename(OPENSSL_INIT_SETTINGS *init,
+                                      const char* filename);
+ int OPENSSL_INIT_set_config_file_flags(OPENSSL_INIT_SETTINGS *init,
+                                        unsigned long flags);
  int OPENSSL_INIT_set_config_appname(OPENSSL_INIT_SETTINGS *init,
                                      const char* name);
  void OPENSSL_INIT_free(OPENSSL_INIT_SETTINGS *init);
@@ -96,7 +101,7 @@ B<OPENSSL_INIT_ADD_ALL_DIGESTS> will be ignored.
 
 With this option an OpenSSL configuration file will be automatically loaded and
 used by calling OPENSSL_config(). This is not a default option for libcrypto.
-From OpenSSL 1.1.1 this is a default option for libssl (see
+As of OpenSSL 1.1.1 this is a default option for libssl (see
 L<OPENSSL_init_ssl(3)> for further details about libssl initialisation). See the
 description of OPENSSL_INIT_new(), below.
 
@@ -203,12 +208,22 @@ the library when the thread exits. This should only be called directly if
 resources should be freed at an earlier time, or under the circumstances
 described in the NOTES section below.
 
-The B<OPENSSL_INIT_LOAD_CONFIG> flag will load a default configuration
-file. For optional configuration file settings, an B<OPENSSL_INIT_SETTINGS>
-must be created and used.
-The routines OPENSSL_init_new() and OPENSSL_INIT_set_config_appname() can
-be used to allocate the object and set the application name, and then the
-object can be released with OPENSSL_INIT_free() when done.
+The B<OPENSSL_INIT_LOAD_CONFIG> flag will load a configuration file, as with
+L<CONF_modules_load_file(3)> with NULL filename and application name and the
+B<CONF_MFLAGS_IGNORE_MISSING_FILE>, B<CONF_MFLAGS_IGNORE_RETURN_CODES>  and
+B<CONF_MFLAGS_DEFAULT_SECTION> flags.
+The filename, application name, and flags can be customized by providing a
+non-null B<OPENSSL_INIT_SETTINGS> object.
+The object can be allocated via B<OPENSSL_init_new()>.
+The B<OPENSSL_INIT_set_config_filename()> function can be used to specify a
+non-default filename, which is copied and need not refer to persistent storage.
+Similarly, OPENSSL_INIT_set_config_appname() can be used to specify a
+non-default application name.
+Finally, OPENSSL_INIT_set_file_flags can be used to specify non-default flags.
+If the B<CONF_MFLAGS_IGNORE_RETURN_CODES> flag is not included, any errors in
+the configuration file will cause an error return from B<OPENSSL_init_crypto>
+or indirectly L<OPENSSL_init_ssl(3)>.
+The object can be released with OPENSSL_INIT_free() when done.
 
 =head1 NOTES
 

include/internal/conf.h

@@ -12,11 +12,18 @@
 
 #include <openssl/conf.h>
 
+#define DEFAULT_CONF_MFLAGS \
+    (CONF_MFLAGS_DEFAULT_SECTION | \
+     CONF_MFLAGS_IGNORE_MISSING_FILE | \
+     CONF_MFLAGS_IGNORE_RETURN_CODES)
+
 struct ossl_init_settings_st {
+    char *filename;
     char *appname;
+    unsigned long flags;
 };
 
-void openssl_config_int(const char *appname);
+int openssl_config_int(const OPENSSL_INIT_SETTINGS *);
 void openssl_no_config_int(void);
 void conf_modules_free_int(void);
 

include/openssl/crypto.h

@@ -405,8 +405,12 @@ void OPENSSL_thread_stop(void);
 /* Low-level control of initialization */
 OPENSSL_INIT_SETTINGS *OPENSSL_INIT_new(void);
 # ifndef OPENSSL_NO_STDIO
+int OPENSSL_INIT_set_config_filename(OPENSSL_INIT_SETTINGS *settings,
+                                     const char *config_filename);
+void OPENSSL_INIT_set_config_file_flags(OPENSSL_INIT_SETTINGS *settings,
+                                        unsigned long flags);
 int OPENSSL_INIT_set_config_appname(OPENSSL_INIT_SETTINGS *settings,
-                                    const char *config_file);
+                                    const char *config_appname);
 # endif
 void OPENSSL_INIT_free(OPENSSL_INIT_SETTINGS *settings);
 

ssl/ssl_init.c

@@ -195,14 +195,15 @@ int OPENSSL_init_ssl(uint64_t opts, const OPENSSL_INIT_SETTINGS * settings)
         return 0;
     }
 
-    if (!OPENSSL_init_crypto(opts
+    opts |= OPENSSL_INIT_ADD_ALL_CIPHERS
+         |  OPENSSL_INIT_ADD_ALL_DIGESTS
+         |  OPENSSL_INIT_ADD_ALL_MACS;
 #ifndef OPENSSL_NO_AUTOLOAD_CONFIG
-                             | OPENSSL_INIT_LOAD_CONFIG
+    if ((opts & OPENSSL_INIT_NO_LOAD_CONFIG) == 0)
+        opts |= OPENSSL_INIT_LOAD_CONFIG;
 #endif
-                             | OPENSSL_INIT_ADD_ALL_CIPHERS
-                             | OPENSSL_INIT_ADD_ALL_DIGESTS
-                             | OPENSSL_INIT_ADD_ALL_MACS,
-                             settings))
+
+    if (!OPENSSL_init_crypto(opts, settings))
         return 0;
 
     if (!RUN_ONCE(&ssl_base, ossl_init_ssl_base))

util/libcrypto.num

@@ -4620,3 +4620,5 @@ CRYPTO_siv128_set_tag                   4575	3_0_0	EXIST::FUNCTION:SIV
 CRYPTO_siv128_get_tag                   4576	3_0_0	EXIST::FUNCTION:SIV
 CRYPTO_siv128_cleanup                   4577	3_0_0	EXIST::FUNCTION:SIV
 CRYPTO_siv128_speed                     4578	3_0_0	EXIST::FUNCTION:SIV
+OPENSSL_INIT_set_config_filename        4579	3_0_0	EXIST::FUNCTION:STDIO
+OPENSSL_INIT_set_config_file_flags      4580	3_0_0	EXIST::FUNCTION:STDIO