Allow loading of non default providers

This allows OpenVPN to load non-default providers. This is mainly
useful for loading the legacy provider with --providers legacy default

Cherry-pick of 08081aa0a153 to release/2.5. Changes.rst has been adjust to
better fit the changes in 2.5.

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20220512121429.2096164-3-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg24327.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/Changes.rst b/Changes.rst
index 45d2c3f39e4ab204d5845c235e7dac8891fd7c9f..ddfa2941fc3563869588254da911d566cfe0a679 100644 (file)
--- a/Changes.rst
+++ b/Changes.rst
@@ -1,3 +1,23 @@
+Overview of changes in 2.5.7
+============================
+
+New features
+------------
+- Limited OpenSSL 3.0 support
+    OpenSSL 3.0 support has been added. OpenSSL 3.0 support in 2.5 relies
+    on the compatiblity layer and full OpenSSL 3.0 support is coming with
+    OpenVPN 2.6. Only features that impact usage directly have been
+    backported:
+
+    ``--tls-cert-profile insecure``  has been added to allow selecting the
+    lowest  OpenSSL security level (not recommended, use only if you must).
+
+    OpenSSL 3.0 no longer supports the Blowfish (and other deprecated)
+    algorithm by default and the new option ``--providers`` allows loading
+    the legacy provider to renable these algorithms.
+
+
+
 Overview of changes in 2.5.6
 ============================
 

diff --git a/doc/man-sections/generic-options.rst b/doc/man-sections/generic-options.rst
index d5f08839b10368d79b2c2d611efc922653718e2f..18085f9bd6d4b111f69dfd9ffc077a46902366d0 100644 (file)
--- a/doc/man-sections/generic-options.rst
+++ b/doc/man-sections/generic-options.rst
@@ -252,6 +252,18 @@ which mode OpenVPN is configured as.
   This option solves the problem by persisting keys across :code:`SIGUSR1`
   resets, so they don't need to be re-read.
 
+--providers providers
+  Load the list of (OpenSSL) providers. This is mainly useful for using an
+  external provider for key management like tpm2-openssl or to load the
+  legacy provider with
+
+  ::
+
+      --providers legacy default
+
+  Behaviour of changing this option between SIGHUP might not be well behaving.
+  If you need to change/add/remove this option, fully restart OpenVPN.
+
 --remap-usr1 signal
   Control whether internally or externally generated :code:`SIGUSR1` signals
   are remapped to :code:`SIGHUP` (restart without persisting state) or

diff --git a/src/openvpn/crypto_backend.h b/src/openvpn/crypto_backend.h
index b5a122eeeb3942cb97e18821c4e74632d3a47630..a9bb38ed2dc3ebb60c997ff931ee3979b66b5eff 100644 (file)
--- a/src/openvpn/crypto_backend.h
+++ b/src/openvpn/crypto_backend.h
@@ -78,6 +78,21 @@ void crypto_clear_error(void);
  */
 void crypto_init_lib_engine(const char *engine_name);
 
+
+/**
+ * Load the given (OpenSSL) providers
+ * @param provider name of providers to load
+ * @return reference to the loaded provider
+ */
+provider_t *crypto_load_provider(const char *provider);
+
+/**
+ * Unloads the given (OpenSSL) provider
+ * @param provname  name of the provider to unload
+ * @param provider  pointer to the provider to unload
+ */
+void crypto_unload_provider(const char *provname, provider_t *provider);
+
 #ifdef DMALLOC
 /*
  * OpenSSL memory debugging.  If dmalloc debugging is enabled, tell

diff --git a/src/openvpn/crypto_mbedtls.c b/src/openvpn/crypto_mbedtls.c
index 1da99d14743f5e350cbc19614b55f76d4e0f2eba..000815209c9a070a9f03dd0678645baaa77f706e 100644 (file)
--- a/src/openvpn/crypto_mbedtls.c
+++ b/src/openvpn/crypto_mbedtls.c
@@ -69,6 +69,19 @@ crypto_init_lib_engine(const char *engine_name)
         "available");
 }
 
+provider_t *crypto_load_provider(const char *provider)
+{
+    if (provider)
+    {
+        msg(M_WARN, "Note: mbed TLS provider functionality is not available");
+    }
+    return NULL;
+}
+
+void crypto_unload_provider(const char *provname, provider_t *provider)
+{
+}
+
 /*
  *
  * Functions related to the core crypto library

diff --git a/src/openvpn/crypto_mbedtls.h b/src/openvpn/crypto_mbedtls.h
index 816e1397a4a6dc6c38a0f4f524c171e4053bb94b..14614a12dbbd47ee101d969a51e24fb612b48a50 100644 (file)
--- a/src/openvpn/crypto_mbedtls.h
+++ b/src/openvpn/crypto_mbedtls.h
@@ -48,6 +48,9 @@ typedef mbedtls_md_context_t md_ctx_t;
 /** Generic HMAC %context. */
 typedef mbedtls_md_context_t hmac_ctx_t;
 
+/* Use a dummy type for the provider */
+typedef void provider_t;
+
 /** Maximum length of an IV */
 #define OPENVPN_MAX_IV_LENGTH   MBEDTLS_MAX_IV_LENGTH
 

diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c
index 0908e9aa173c42da625cf6847faffa4031402d84..beeaee4b7cafed0890e89f528ecb1a185a1ade86 100644 (file)
--- a/src/openvpn/crypto_openssl.c
+++ b/src/openvpn/crypto_openssl.c
@@ -51,6 +51,10 @@
 #include <openssl/rand.h>
 #include <openssl/ssl.h>
 
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+#include <openssl/provider.h>
+#endif
+
 #if defined(_WIN32) && defined(OPENSSL_NO_EC)
 #error Windows build with OPENSSL_NO_EC: disabling EC key is not supported.
 #endif
@@ -145,6 +149,33 @@ crypto_init_lib_engine(const char *engine_name)
 #endif
 }
 
+provider_t *
+crypto_load_provider(const char *provider)
+{
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+    /* Load providers into the default (NULL) library context */
+    OSSL_PROVIDER *prov = OSSL_PROVIDER_load(NULL, provider);
+    if (!prov)
+    {
+        crypto_msg(M_FATAL, "failed to load provider '%s'", provider);
+    }
+    return prov;
+#else  /* OPENSSL_VERSION_NUMBER >= 0x30000000L */
+    msg(M_WARN, "Note: OpenSSL provider functionality is not available");
+    return NULL;
+#endif
+}
+
+void crypto_unload_provider(const char *provname, provider_t *provider)
+{
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+    if (!OSSL_PROVIDER_unload(provider))
+    {
+        crypto_msg(M_FATAL, "failed to unload provider '%s'", provname);
+    }
+#endif
+}
+
 /*
  *
  * Functions related to the core crypto library

diff --git a/src/openvpn/crypto_openssl.h b/src/openvpn/crypto_openssl.h
index ecc66fbfdaf62ac9b72f4f25863ea6b1a2fff0c8..9bb58adae401a2e5140550e2b9b77f08c8306731 100644 (file)
--- a/src/openvpn/crypto_openssl.h
+++ b/src/openvpn/crypto_openssl.h
@@ -33,6 +33,10 @@
 #include <openssl/hmac.h>
 #include <openssl/md5.h>
 #include <openssl/sha.h>
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+#include <openssl/provider.h>
+#endif
+
 
 /** Generic cipher key type %context. */
 typedef EVP_CIPHER cipher_kt_t;
@@ -49,6 +53,13 @@ typedef EVP_MD_CTX md_ctx_t;
 /** Generic HMAC %context. */
 typedef HMAC_CTX hmac_ctx_t;
 
+#if OPENSSL_VERSION_NUMBER < 0x30000000L
+/* Use a dummy type for the provider */
+typedef void provider_t;
+#else
+typedef OSSL_PROVIDER provider_t;
+#endif
+
 /** Maximum length of an IV */
 #define OPENVPN_MAX_IV_LENGTH   EVP_MAX_IV_LENGTH
 

diff --git a/src/openvpn/openvpn.c b/src/openvpn/openvpn.c
index e03d254506926844f4026dbdf2354ca1a7710f25..1cd8f1b308a04e9cc2c80de5900a50cc796dc03c 100644 (file)
--- a/src/openvpn/openvpn.c
+++ b/src/openvpn/openvpn.c
@@ -112,14 +112,27 @@ void init_early(struct context *c)
     /* init verbosity and mute levels */
     init_verb_mute(c, IVM_LEVEL_1);
 
+    /* Initialise OpenSSL provider, this needs to be initialised this
+    * early since option post-processing and also openssl info
+    * printing depends on it */
+    for (int j=1; j < MAX_PARMS && c->options.providers.names[j]; j++)
+    {
+        c->options.providers.providers[j] =
+            crypto_load_provider(c->options.providers.names[j]);
+    }
 }
 
 static void uninit_early(struct context *c)
 {
     net_ctx_free(&c->net_ctx);
+    for (int j=1; j < MAX_PARMS && c->options.providers.providers[j]; j++)
+    {
+        crypto_unload_provider(c->options.providers.names[j],
+                               c->options.providers.providers[j]);
+    }
+    net_ctx_free(&c->net_ctx);
 }
 
-
 /**************************************************************************/
 /**
  * OpenVPN's main init-run-cleanup loop.

diff --git a/src/openvpn/options.c b/src/openvpn/options.c
index e0b273bdd43b45b8c1fb62d672fab68907b6a419..f6ef02ae8ad81a80aabfcda8f40b880300d1b193 100644 (file)
--- a/src/openvpn/options.c
+++ b/src/openvpn/options.c
@@ -602,6 +602,7 @@ static const char usage_message[] =
     "                : Use --show-tls to see a list of supported TLS ciphers (suites).\n"
     "--tls-cert-profile p : Set the allowed certificate crypto algorithm profile\n"
     "                  (default=legacy).\n"
+    "--providers l   : A list l of OpenSSL providers to load.\n"
     "--tls-timeout n : Packet retransmit timeout on TLS control channel\n"
     "                  if no ACK from remote within n seconds (default=%d).\n"
     "--reneg-bytes n : Renegotiate data chan. key after n bytes sent and recvd.\n"
@@ -8129,6 +8130,13 @@ add_option(struct options *options,
         options->keysize = keysize;
     }
 #endif
+    else if (streq(p[0], "providers") && p[1])
+    {
+        for (size_t j = 1; j < MAX_PARMS && p[j] != NULL;j++)
+        {
+            options->providers.names[j] = p[j];
+        }
+    }
 #ifdef ENABLE_PREDICTION_RESISTANCE
     else if (streq(p[0], "use-prediction-resistance") && !p[1])
     {

diff --git a/src/openvpn/options.h b/src/openvpn/options.h
index 251660fdc9c904738b3cecdc7faf7b0b80626c19..37220904265b943723b404d6021a46255d538dce 100644 (file)
--- a/src/openvpn/options.h
+++ b/src/openvpn/options.h
@@ -176,6 +176,14 @@ struct remote_list
     struct remote_entry *array[CONNECTION_LIST_SIZE];
 };
 
+struct provider_list
+{
+    /* Names of the providers */
+    const char *names[MAX_PARMS];
+    /* Pointers to the loaded providers to unload them */
+    provider_t *providers[MAX_PARMS];
+};
+
 enum vlan_acceptable_frames
 {
     VLAN_ONLY_TAGGED,
@@ -519,6 +527,7 @@ struct options
     const char *prng_hash;
     int prng_nonce_secret_len;
     const char *engine;
+    struct provider_list providers;
     bool replay;
     bool mute_replay_warnings;
     int replay_window;