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)

11 files changed, 140 insertions, 36 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;
diff --git a/doc/man3/CONF_modules_load_file.pod b/doc/man3/CONF_modules_load_file.pod
index ecf294a2c6..211eca06fa 100644
--- a/doc/man3/CONF_modules_load_file.pod
+++ b/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.
 
diff --git a/doc/man3/OPENSSL_init_crypto.pod b/doc/man3/OPENSSL_init_crypto.pod
index b53ab6bd10..a6425265a9 100644
--- a/doc/man3/OPENSSL_init_crypto.pod
+++ b/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
 
diff --git a/include/internal/conf.h b/include/internal/conf.h
index dc1e72508a..0b818c6d92 100644
--- a/include/internal/conf.h
+++ b/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);
 
diff --git a/include/openssl/crypto.h b/include/openssl/crypto.h
index d23d9b3156..150fc1ae54 100644
--- a/include/openssl/crypto.h
+++ b/include/openssl/crypto.h
@@ -397,8 +397,12 @@ 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);
 
diff --git a/ssl/ssl_init.c b/ssl/ssl_init.c
index 96526472c5..e8353ecd42 100644
--- a/ssl/ssl_init.c
+++ b/ssl/ssl_init.c
@@ -195,13 +195,14 @@ 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;
 #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,
-                             settings))
+
+    if (!OPENSSL_init_crypto(opts, settings))
         return 0;
 
     if (!RUN_ONCE(&ssl_base, ossl_init_ssl_base))
diff --git a/util/libcrypto.num b/util/libcrypto.num
index bad3a3814e..32c64cb2c7 100644
--- a/util/libcrypto.num
+++ b/util/libcrypto.num
@@ -4577,3 +4577,5 @@ OCSP_resp_get0_respdata                 4530	1_1_0j	EXIST::FUNCTION:OCSP
 EVP_MD_CTX_set_pkey_ctx                 4531	1_1_1	EXIST::FUNCTION:
 EVP_PKEY_meth_set_digest_custom         4532	1_1_1	EXIST::FUNCTION:
 EVP_PKEY_meth_get_digest_custom         4533	1_1_1	EXIST::FUNCTION:
+OPENSSL_INIT_set_config_filename        4534	1_1_1b	EXIST::FUNCTION:STDIO
+OPENSSL_INIT_set_config_file_flags      4535	1_1_1b	EXIST::FUNCTION:STDIO