libcrypto: constify most error string tables

These constitute the bulk of the remaining global mutable state in
libcrypto. This commit moves most of them into data.rel.ro, leaving
out ERR_str_{functs,libraries,reasons} (which require a slightly
different approach) and SYS_str_reasons which is populated on startup.

The main observation is that if ERR_load_strings() is called with a 0 lib
argument, the ERR_STRING_DATA argument is not actually modified. We could
use this fact to cast away const on the caller side and be done with it.
We can make this cleaner by adding a helper ERR_load_const_strings() which
explicitly avoids the assignment to str->error overriding the error code
already set in the table.

In order for this to work, we need to sprinkle some const in err/err.c.
CMS called ERR_load_strings() with non-0 lib argument, but this didn't
actually modify the error data since it ored in the value already stored
in the table.

Annoyingly, we need to cast const away once, namely in the call to
lh_insert() in int_err_set_item(). Fixing this would require changing
the public API and is going to be tricky since it requires that the
LHASH_DOALL_FN_* types adjust.

ok jsing

2 files changed, 153 insertions, 17 deletions

diff --git a/src/lib/libcrypto/err/err.c b/src/lib/libcrypto/err/err.c
index a7b13a5404..583293e793 100644
--- a/src/lib/libcrypto/err/err.c
+++ b/src/lib/libcrypto/err/err.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: err.c,v 1.60 2024/03/02 11:37:13 tb Exp $ */
+/* $OpenBSD: err.c,v 1.61 2024/06/24 06:43:22 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -244,9 +244,9 @@ struct st_ERR_FNS {
         /* Works on the "error_hash" string table */
         LHASH_OF(ERR_STRING_DATA) *(*cb_err_get)(int create);
         void (*cb_err_del)(void);
-        ERR_STRING_DATA *(*cb_err_get_item)(const ERR_STRING_DATA *);
-        ERR_STRING_DATA *(*cb_err_set_item)(ERR_STRING_DATA *);
-        ERR_STRING_DATA *(*cb_err_del_item)(ERR_STRING_DATA *);
+        const ERR_STRING_DATA *(*cb_err_get_item)(const ERR_STRING_DATA *);
+        const ERR_STRING_DATA *(*cb_err_set_item)(const ERR_STRING_DATA *);
+        const ERR_STRING_DATA *(*cb_err_del_item)(const ERR_STRING_DATA *);
         /* Works on the "thread_hash" error-state table */
         LHASH_OF(ERR_STATE) *(*cb_thread_get)(int create);
         void (*cb_thread_release)(LHASH_OF(ERR_STATE) **hash);
@@ -260,9 +260,9 @@ struct st_ERR_FNS {
 /* Predeclarations of the "err_defaults" functions */
 static LHASH_OF(ERR_STRING_DATA) *int_err_get(int create);
 static void int_err_del(void);
-static ERR_STRING_DATA *int_err_get_item(const ERR_STRING_DATA *);
-static ERR_STRING_DATA *int_err_set_item(ERR_STRING_DATA *);
-static ERR_STRING_DATA *int_err_del_item(ERR_STRING_DATA *);
+static const ERR_STRING_DATA *int_err_get_item(const ERR_STRING_DATA *);
+static const ERR_STRING_DATA *int_err_set_item(const ERR_STRING_DATA *);
+static const ERR_STRING_DATA *int_err_del_item(const ERR_STRING_DATA *);
 static LHASH_OF(ERR_STATE) *int_thread_get(int create);
 static void int_thread_release(LHASH_OF(ERR_STATE) **hash);
 static ERR_STATE *int_thread_get_item(const ERR_STATE *);
@@ -369,7 +369,7 @@ int_err_del(void)
         CRYPTO_w_unlock(CRYPTO_LOCK_ERR);
 }
 
-static ERR_STRING_DATA *
+static const ERR_STRING_DATA *
 int_err_get_item(const ERR_STRING_DATA *d)
 {
         ERR_STRING_DATA *p;
@@ -387,10 +387,10 @@ int_err_get_item(const ERR_STRING_DATA *d)
         return p;
 }
 
-static ERR_STRING_DATA *
-int_err_set_item(ERR_STRING_DATA *d)
+static const ERR_STRING_DATA *
+int_err_set_item(const ERR_STRING_DATA *d)
 {
-        ERR_STRING_DATA *p;
+        const ERR_STRING_DATA *p;
         LHASH_OF(ERR_STRING_DATA) *hash;
 
         err_fns_check();
@@ -399,14 +399,14 @@ int_err_set_item(ERR_STRING_DATA *d)
                 return NULL;
 
         CRYPTO_w_lock(CRYPTO_LOCK_ERR);
-        p = lh_ERR_STRING_DATA_insert(hash, d);
+        p = lh_ERR_STRING_DATA_insert(hash, (void *)d);
         CRYPTO_w_unlock(CRYPTO_LOCK_ERR);
 
         return p;
 }
 
-static ERR_STRING_DATA *
-int_err_del_item(ERR_STRING_DATA *d)
+static const ERR_STRING_DATA *
+int_err_del_item(const ERR_STRING_DATA *d)
 {
         ERR_STRING_DATA *p;
         LHASH_OF(ERR_STRING_DATA) *hash;
@@ -693,6 +693,16 @@ ERR_load_strings(int lib, ERR_STRING_DATA *str)
 LCRYPTO_ALIAS(ERR_load_strings);
 
 void
+ERR_load_const_strings(const ERR_STRING_DATA *str)
+{
+        ERR_load_ERR_strings();
+        while (str->error) {
+                ERRFN(err_set_item)(str);
+                str++;
+        }
+}
+
+void
 ERR_unload_strings(int lib, ERR_STRING_DATA *str)
 {
         /* Prayer and clean living lets you ignore errors, OpenSSL style */
@@ -964,7 +974,8 @@ LCRYPTO_ALIAS(ERR_error_string);
 const char *
 ERR_lib_error_string(unsigned long e)
 {
-        ERR_STRING_DATA d, *p;
+        const ERR_STRING_DATA *p;
+        ERR_STRING_DATA d;
         unsigned long l;
 
         if (!OPENSSL_init_crypto(0, NULL))
@@ -981,7 +992,8 @@ LCRYPTO_ALIAS(ERR_lib_error_string);
 const char *
 ERR_func_error_string(unsigned long e)
 {
-        ERR_STRING_DATA d, *p;
+        const ERR_STRING_DATA *p;
+        ERR_STRING_DATA d;
         unsigned long l, f;
 
         err_fns_check();
@@ -996,7 +1008,8 @@ LCRYPTO_ALIAS(ERR_func_error_string);
 const char *
 ERR_reason_error_string(unsigned long e)
 {
-        ERR_STRING_DATA d, *p = NULL;
+        const ERR_STRING_DATA *p = NULL;
+        ERR_STRING_DATA d;
         unsigned long l, r;
 
         err_fns_check();
diff --git a/src/lib/libcrypto/err/err_local.h b/src/lib/libcrypto/err/err_local.h
new file mode 100644
index 0000000000..d091b979cc
--- /dev/null
+++ b/src/lib/libcrypto/err/err_local.h
@@ -0,0 +1,123 @@
+/*      $OpenBSD: err_local.h,v 1.1 2024/06/24 06:43:22 tb Exp $ */
+/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
+ * All rights reserved.
+ *
+ * This package is an SSL implementation written
+ * by Eric Young (eay@cryptsoft.com).
+ * The implementation was written so as to conform with Netscapes SSL.
+ *
+ * This library is free for commercial and non-commercial use as long as
+ * the following conditions are aheared to.  The following conditions
+ * apply to all code found in this distribution, be it the RC4, RSA,
+ * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
+ * included with this distribution is covered by the same copyright terms
+ * except that the holder is Tim Hudson (tjh@cryptsoft.com).
+ *
+ * Copyright remains Eric Young's, and as such any Copyright notices in
+ * the code are not to be removed.
+ * If this package is used in a product, Eric Young should be given attribution
+ * as the author of the parts of the library used.
+ * This can be in the form of a textual message at program startup or
+ * in documentation (online or textual) provided with the package.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *    "This product includes cryptographic software written by
+ *     Eric Young (eay@cryptsoft.com)"
+ *    The word 'cryptographic' can be left out if the rouines from the library
+ *    being used are not cryptographic related :-).
+ * 4. If you include any Windows specific code (or a derivative thereof) from
+ *    the apps directory (application code) you must include an acknowledgement:
+ *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * The licence and distribution terms for any publically available version or
+ * derivative of this code cannot be changed.  i.e. this code cannot simply be
+ * copied and put under another distribution licence
+ * [including the GNU Public Licence.]
+ */
+/* ====================================================================
+ * Copyright (c) 1998-2006 The OpenSSL Project.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. All advertising materials mentioning features or use of this
+ *    software must display the following acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
+ *
+ * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For written permission, please contact
+ *    openssl-core@openssl.org.
+ *
+ * 5. Products derived from this software may not be called "OpenSSL"
+ *    nor may "OpenSSL" appear in their names without prior written
+ *    permission of the OpenSSL Project.
+ *
+ * 6. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
+ * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This product includes cryptographic software written by Eric Young
+ * (eay@cryptsoft.com).  This product includes software written by Tim
+ * Hudson (tjh@cryptsoft.com).
+ *
+ */
+
+#include <openssl/err.h>
+
+#ifndef HEADER_ERR_LOCAL_H
+#define HEADER_ERR_LOCAL_H
+
+__BEGIN_HIDDEN_DECLS
+
+void ERR_load_const_strings(const ERR_STRING_DATA *str);
+
+__END_HIDDEN_DECLS
+
+#endif /* HEADER_ERR_LOCAL_H */