kerberos: Fix numerous segfaults when using weak crypto

Weak crypto is provided by the openssl legacy provider which is
not load by default. Load the legacy providers as needed.

When the legacy provider is loaded into the default context the default
provider will no longer be automatically loaded. Without the default
provider the various kerberos applicaions and functions will abort().

This is the second attempt at this patch. Instead of linking
secure/lib/libcrypto at build time we now link it at runtime, avoiding
buildworld failures under Linux and MacOS. This is because
TARGET_ENDIANNESS is undefined at pre-build time.

PR:		272835
MFC after:	3 days
X-MFC:		only to stable/14
Tested by:	netchild
		Joerg Pulz <Joerg.Pulz@frm2.tum.de> (previous version)

crypto/heimdal/lib/kadm5/create_s.c

@@ -169,6 +169,10 @@ kadm5_s_create_principal(void *server_handle,
     ent.entry.keys.len = 0;
     ent.entry.keys.val = NULL;
 
+    ret = fbsd_ossl_provider_load();
+    if (ret)
+	goto out;
+
     ret = _kadm5_set_keys(context, &ent.entry, password);
     if (ret)
 	goto out;

crypto/heimdal/lib/kadm5/kadm5_locl.h

@@ -79,5 +79,6 @@
 #include <der.h>
 #include <parse_units.h>
 #include "private.h"
+#include "fbsd_ossl_provider.h"
 
 #endif /* __KADM5_LOCL_H__ */

crypto/heimdal/lib/krb5/context.c

@@ -392,6 +392,10 @@ krb5_init_context(krb5_context *context)
     }
     HEIMDAL_MUTEX_init(p->mutex);
 
+    ret = fbsd_ossl_provider_load();
+    if(ret)
+	goto out;
+
     p->flags |= KRB5_CTX_F_HOMEDIR_ACCESS;
 
     ret = krb5_get_default_config_files(&files);

crypto/heimdal/lib/krb5/crypto.c

@@ -2054,6 +2054,9 @@ krb5_crypto_init(krb5_context context,
 	*crypto = NULL;
 	return ret;
     }
+    ret = fbsd_ossl_provider_load();
+    if (ret)
+	return ret;
     (*crypto)->key.schedule = NULL;
     (*crypto)->num_key_usage = 0;
     (*crypto)->key_usage = NULL;

crypto/heimdal/lib/krb5/salt.c

@@ -43,6 +43,8 @@ krb5_salttype_to_string (krb5_context context,
     struct _krb5_encryption_type *e;
     struct salt_type *st;
 
+    (void) fbsd_ossl_provider_load();
+
     e = _krb5_find_enctype (etype);
     if (e == NULL) {
 	krb5_set_error_message(context, KRB5_PROG_ETYPE_NOSUPP,
@@ -75,6 +77,8 @@ krb5_string_to_salttype (krb5_context context,
     struct _krb5_encryption_type *e;
     struct salt_type *st;
 
+    (void) fbsd_ossl_provider_load();
+
     e = _krb5_find_enctype (etype);
     if (e == NULL) {
 	krb5_set_error_message(context, KRB5_PROG_ETYPE_NOSUPP,
@@ -196,6 +200,7 @@ krb5_string_to_key_data_salt_opaque (krb5_context context,
 			       enctype);
 	return KRB5_PROG_ETYPE_NOSUPP;
     }
+    (void) fbsd_ossl_provider_load();
     for(st = et->keytype->string_to_key; st && st->type; st++)
 	if(st->type == salt.salttype)
 	    return (*st->string_to_key)(context, enctype, password,

crypto/heimdal/lib/roken/version-script.map

@@ -13,6 +13,7 @@ HEIMDAL_ROKEN_1.0 {
 		ct_memcmp;
 		err;
 		errx;
+		fbsd_ossl_provider_load;
 		free_getarg_strings;
 		get_default_username;
 		get_window_size;

kerberos5/include/crypto-headers.h

@@ -17,5 +17,9 @@
 #include <openssl/ec.h>
 #include <openssl/ecdsa.h>
 #include <openssl/ecdh.h>
+#if defined(OPENSSL_VERSION_MAJOR) && (OPENSSL_VERSION_MAJOR >= 3)
+#include <openssl/provider.h>
+#include "fbsd_ossl_provider.h"
+#endif
 
 #endif /* __crypto_headers_h__ */

kerberos5/include/fbsd_ossl_provider.h

@@ -0,0 +1,4 @@
+#ifndef __fbsd_ossl_provider_h
+#define __fbsd_ossl_provider_h
+int  fbsd_ossl_provider_load(void);
+#endif

kerberos5/lib/libroken/Makefile

@@ -74,9 +74,13 @@ SRCS=	base64.c \
 	vis.c \
 	warnerr.c \
 	write_pid.c \
-	xfree.c
+	xfree.c \
+	fbsd_ossl_provider_load.c
 
-CFLAGS+=-I${KRB5DIR}/lib/roken -I.
+CFLAGS+=-I${KRB5DIR}/lib/roken \
+	-I${SRCTOP}/kerberos5/include \
+	-I${KRB5DIR}/lib/krb5 \
+	-I${SRCTOP}/crypto/openssl/include -I.
 
 CLEANFILES= roken.h
 

kerberos5/lib/libroken/fbsd_ossl_provider_load.c

@@ -0,0 +1,77 @@
+#include <dlfcn.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <openssl/provider.h>
+
+#if defined(OPENSSL_VERSION_MAJOR) && (OPENSSL_VERSION_MAJOR >= 3)
+static void fbsd_ossl_provider_unload(void);
+static void print_dlerror(char *);
+static OSSL_PROVIDER *legacy;
+static OSSL_PROVIDER *deflt;
+static int providers_loaded = 0;
+static OSSL_PROVIDER * (*ossl_provider_load)(OSSL_LIB_CTX *, const char*) = NULL;
+static int (*ossl_provider_unload)(OSSL_PROVIDER *) = NULL;
+static void *crypto_lib_handle = NULL;
+
+static void
+fbsd_ossl_provider_unload(void)
+{
+	if (ossl_provider_unload == NULL) {
+		if (!(ossl_provider_unload = (int (*)(OSSL_PROVIDER*)) dlsym(crypto_lib_handle, "OSSL_PROVIDER_unload"))) {
+			print_dlerror("Unable to link OSSL_PROVIDER_unload");
+			return;
+		}
+	}
+	if (providers_loaded == 1) {
+		(*ossl_provider_unload)(legacy);
+		(*ossl_provider_unload)(deflt);
+		providers_loaded = 0;
+	}
+}
+
+static void
+print_dlerror(char *message)
+{
+	char *errstr;
+
+	if ((errstr = dlerror()) != NULL)
+		fprintf(stderr, "%s: %s\n",
+			message, errstr);
+}
+#endif
+
+int
+fbsd_ossl_provider_load(void)
+{
+#if defined(OPENSSL_VERSION_MAJOR) && (OPENSSL_VERSION_MAJOR >= 3)
+	if (crypto_lib_handle == NULL) {
+		if (!(crypto_lib_handle = dlopen("/usr/lib/libcrypto.so",
+		    RTLD_LAZY|RTLD_GLOBAL))) {
+			print_dlerror("Unable to load libcrypto.so");
+			return (EINVAL);
+		}
+	}
+	if (ossl_provider_load == NULL) {
+		if (!(ossl_provider_load = (OSSL_PROVIDER * (*)(OSSL_LIB_CTX*, const char *)) dlsym(crypto_lib_handle, "OSSL_PROVIDER_load"))) {
+			print_dlerror("Unable to link OSSL_PROVIDER_load");
+			return(ENOENT);
+		}
+	}
+
+	if (providers_loaded == 0) {
+		if ((legacy = (*ossl_provider_load)(NULL, "legacy")) == NULL)
+			return (EINVAL);
+		if ((deflt = (*ossl_provider_load)(NULL, "default")) == NULL) {
+			(*ossl_provider_unload)(legacy);
+			return (EINVAL);
+		}
+		if (atexit(fbsd_ossl_provider_unload)) {
+			fbsd_ossl_provider_unload();
+			return (errno);
+		}
+		providers_loaded = 1;
+	}
+#endif
+	return (0);
+}