Rewrite CRYPTO_EX_DATA.

CRYPTO_EX_DATA exists as a way to allow an application to attach data to
various components in libcrypto and libssl. The general idea is that there
are various "classes" (e.g. RSA) and an application can get an "index"
(which can have new/dup/free functions provided). The application can then
use the index to store a pointer to some form of data within that class,
for later retrieval.

However, even by OpenSSL standards, this is an insane API. The current
implementation allows for data to be set without calling new, indexes
can be used without allocation, new can be called without actually getting
an index and dup can be called either after new or without new (see regress
and RSA_get_ex_new_index(3)/CRYPTO_set_ex_data(3) for more details). On
top of this, the previous "overhaul" of the code was written to be
infinitely extensible.

For now, the rewrite intends to maintain the existing behaviour - once we
bed this down we can attempt to ratchet the API requirements and require
some sort of sensible sequence. The only intentional change is that there
is now a hard limit on the number of indexes that can be allocated
(previously there was none, relying only on ENOMEM).

ok tb@

1 files changed, 417 insertions, 0 deletions

diff --git a/src/lib/libcrypto/crypto_ex_data.c b/src/lib/libcrypto/crypto_ex_data.c
new file mode 100644
index 0000000000..947e02669b
--- /dev/null
+++ b/src/lib/libcrypto/crypto_ex_data.c
@@ -0,0 +1,417 @@
+/* $OpenBSD: crypto_ex_data.c,v 1.1 2024/08/02 10:48:54 jsing Exp $ */
+/*
+ * Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <stdlib.h>
+
+#include <openssl/crypto.h>
+
+#define CRYPTO_EX_DATA_MAX_INDEX 16
+
+struct crypto_ex_data {
+        int class_index;
+        void **slots;
+        size_t slots_len;
+};
+
+struct crypto_ex_data_index {
+        CRYPTO_EX_new *new_func;
+        CRYPTO_EX_dup *dup_func;
+        CRYPTO_EX_free *free_func;
+        long argl;
+        void *argp;
+};
+
+struct crypto_ex_data_class {
+        struct crypto_ex_data_index **indexes;
+        size_t indexes_len;
+        size_t next_index;
+};
+
+static struct crypto_ex_data_class **classes;
+
+static int
+crypto_ex_data_classes_init(void)
+{
+        struct crypto_ex_data_class **classes_new = NULL;
+
+        if (classes != NULL)
+                return 1;
+
+        if ((classes_new = calloc(CRYPTO_EX_INDEX__COUNT,
+            sizeof(struct crypto_ex_data_index))) == NULL)
+                return 0;
+
+        CRYPTO_w_lock(CRYPTO_LOCK_EX_DATA);
+        if (classes == NULL) {
+                classes = classes_new;
+                classes_new = NULL;
+        }
+        CRYPTO_w_unlock(CRYPTO_LOCK_EX_DATA);
+
+        free(classes_new);
+
+        return 1;
+}
+
+static struct crypto_ex_data_class *
+crypto_ex_data_class_lookup(int class_index)
+{
+        struct crypto_ex_data_class *class;
+
+        if (classes == NULL)
+                return NULL;
+        if (class_index < 0 || class_index >= CRYPTO_EX_INDEX__COUNT)
+                return NULL;
+
+        CRYPTO_r_lock(CRYPTO_LOCK_EX_DATA);
+        class = classes[class_index];
+        CRYPTO_r_unlock(CRYPTO_LOCK_EX_DATA);
+
+        return class;
+}
+
+int
+CRYPTO_get_ex_new_index(int class_index, long argl, void *argp,
+    CRYPTO_EX_new *new_func, CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func)
+{
+        struct crypto_ex_data_class *new_class = NULL;
+        struct crypto_ex_data_index *index = NULL;
+        struct crypto_ex_data_class *class;
+        int idx = -1;
+
+        if (!crypto_ex_data_classes_init())
+                goto err;
+
+        if (class_index < 0 || class_index >= CRYPTO_EX_INDEX__COUNT)
+                goto err;
+
+        if ((class = classes[class_index]) == NULL) {
+                if ((new_class = calloc(1,
+                    sizeof(struct crypto_ex_data_class))) == NULL)
+                        goto err;
+                if ((new_class->indexes = calloc(CRYPTO_EX_DATA_MAX_INDEX,
+                    sizeof(struct crypto_ex_data_index))) == NULL)
+                        goto err;
+                new_class->indexes_len = CRYPTO_EX_DATA_MAX_INDEX;
+                new_class->next_index = 1;
+
+                CRYPTO_w_lock(CRYPTO_LOCK_EX_DATA);
+                if (classes[class_index] == NULL) {
+                        classes[class_index] = new_class;
+                        new_class = NULL;
+                }
+                CRYPTO_w_unlock(CRYPTO_LOCK_EX_DATA);
+
+                class = classes[class_index];
+        }
+
+        if ((index = calloc(1, sizeof(struct crypto_ex_data_index))) == NULL)
+                goto err;
+
+        index->new_func = new_func;
+        index->dup_func = dup_func;
+        index->free_func = free_func;
+
+        index->argl = argl;
+        index->argp = argp;
+
+        CRYPTO_w_lock(CRYPTO_LOCK_EX_DATA);
+        if (class->next_index < class->indexes_len) {
+                idx = class->next_index++;
+                class->indexes[idx] = index;
+                index = NULL;
+        }
+        CRYPTO_w_unlock(CRYPTO_LOCK_EX_DATA);
+
+
+ err:
+        if (new_class != NULL) {
+                free(new_class->indexes);
+                free(new_class);
+        }
+        free(index);
+
+        return idx;
+}
+LCRYPTO_ALIAS(CRYPTO_get_ex_new_index);
+
+void
+CRYPTO_cleanup_all_ex_data(void)
+{
+        struct crypto_ex_data_class *class;
+        int i, j;
+
+        if (classes == NULL)
+                return;
+
+        for (i = 0; i < CRYPTO_EX_INDEX__COUNT; i++) {
+                if ((class = classes[i]) == NULL)
+                        continue;
+
+                if (class->indexes != NULL) {
+                        for (j = 0; j < CRYPTO_EX_DATA_MAX_INDEX; j++)
+                                free(class->indexes[j]);
+                }
+
+                free(class);
+        }
+
+        free(classes);
+        classes = NULL;
+}
+LCRYPTO_ALIAS(CRYPTO_cleanup_all_ex_data);
+
+static void
+crypto_ex_data_clear(CRYPTO_EX_DATA *exdata)
+{
+        struct crypto_ex_data *ced;
+
+        if (exdata == NULL)
+                return;
+
+        if ((ced = exdata->sk) != NULL) {
+                freezero(ced->slots, ced->slots_len * sizeof(void *));
+                freezero(ced, sizeof(*ced));
+        }
+
+        exdata->sk = NULL;
+}
+
+static int
+crypto_ex_data_init(CRYPTO_EX_DATA *exdata)
+{
+        struct crypto_ex_data *ced = NULL;
+
+        if (exdata->sk != NULL)
+                goto err;
+
+        if ((ced = calloc(1, sizeof(struct crypto_ex_data))) == NULL)
+                goto err;
+
+        ced->class_index = -1;
+
+        if ((ced->slots = calloc(CRYPTO_EX_DATA_MAX_INDEX, sizeof(void *))) == NULL)
+                goto err;
+        ced->slots_len = CRYPTO_EX_DATA_MAX_INDEX;
+
+        exdata->sk = ced;
+
+        return 1;
+
+ err:
+        if (ced != NULL) {
+                free(ced->slots);
+                free(ced);
+        }
+        crypto_ex_data_clear(exdata);
+
+        return 0;
+}
+
+int
+CRYPTO_new_ex_data(int class_index, void *parent, CRYPTO_EX_DATA *exdata)
+{
+        struct crypto_ex_data_class *class;
+        struct crypto_ex_data_index *index;
+        struct crypto_ex_data *ced;
+        size_t i, last_index;
+
+        if (!crypto_ex_data_init(exdata))
+                goto err;
+        if ((ced = exdata->sk) == NULL)
+                goto err;
+
+        if (!crypto_ex_data_classes_init())
+                goto err;
+        if ((class = crypto_ex_data_class_lookup(class_index)) == NULL)
+                goto done;
+
+        ced->class_index = class_index;
+
+        /* Existing indexes are immutable, we just have to know when to stop. */
+        CRYPTO_r_lock(CRYPTO_LOCK_EX_DATA);
+        last_index = class->next_index;
+        CRYPTO_r_unlock(CRYPTO_LOCK_EX_DATA);
+
+        for (i = 0; i < last_index; i++) {
+                if ((index = class->indexes[i]) == NULL)
+                        continue;
+                if (index->new_func == NULL)
+                        continue;
+                if (!index->new_func(parent, NULL, exdata, i, index->argl,
+                    index->argp))
+                        goto err;
+        }
+
+ done:
+        return 1;
+
+ err:
+        CRYPTO_free_ex_data(class_index, parent, exdata);
+
+        return 0;
+}
+LCRYPTO_ALIAS(CRYPTO_new_ex_data);
+
+int
+CRYPTO_dup_ex_data(int class_index, CRYPTO_EX_DATA *dst, CRYPTO_EX_DATA *src)
+{
+        struct crypto_ex_data *dst_ced, *src_ced;
+        struct crypto_ex_data_class *class;
+        struct crypto_ex_data_index *index;
+        size_t i, last_index;
+        void *val;
+
+        if (dst == NULL || src == NULL)
+                goto err;
+
+        /*
+         * Some code calls CRYPTO_new_ex_data() before dup, others never call
+         * CRYPTO_new_ex_data()... so we get to handle both.
+         */
+        /* XXX - parent == NULL? */
+        CRYPTO_free_ex_data(class_index, NULL, dst);
+
+        if (!crypto_ex_data_init(dst))
+                goto err;
+
+        if ((dst_ced = dst->sk) == NULL)
+                goto err;
+        if ((src_ced = src->sk) == NULL)
+                goto err;
+
+        if ((class = crypto_ex_data_class_lookup(class_index)) == NULL) {
+                for (i = 0; i < CRYPTO_EX_DATA_MAX_INDEX; i++)
+                        dst_ced->slots[i] = src_ced->slots[i];
+                goto done;
+        }
+
+        OPENSSL_assert(src_ced->class_index == class_index);
+
+        dst_ced->class_index = class_index;
+
+        /* Existing indexes are immutable, we just have to know when to stop. */
+        CRYPTO_r_lock(CRYPTO_LOCK_EX_DATA);
+        last_index = class->next_index;
+        CRYPTO_r_unlock(CRYPTO_LOCK_EX_DATA);
+
+        for (i = 0; i < last_index; i++) {
+                if ((index = class->indexes[i]) == NULL)
+                        continue;
+
+                /* If there is no dup function, we copy the pointer. */
+                val = src_ced->slots[i];
+                if (index->dup_func != NULL) {
+                        if (!index->dup_func(dst, src, &val, i, index->argl,
+                            index->argp))
+                                goto err;
+                }
+                /* If the dup function set data, we will potentially leak. */
+                if (dst_ced->slots[i] != NULL)
+                        goto err;
+                dst_ced->slots[i] = val;
+        }
+
+ done:
+        return 1;
+
+ err:
+        /* XXX - parent == NULL? */
+        CRYPTO_free_ex_data(class_index, NULL, dst);
+
+        return 0;
+}
+LCRYPTO_ALIAS(CRYPTO_dup_ex_data);
+
+void
+CRYPTO_free_ex_data(int class_index, void *parent, CRYPTO_EX_DATA *exdata)
+{
+        struct crypto_ex_data_class *class;
+        struct crypto_ex_data_index *index;
+        struct crypto_ex_data *ced;
+        size_t i, last_index;
+
+        if (exdata == NULL)
+                return;
+        if ((ced = exdata->sk) == NULL)
+                goto done;
+        if (ced->class_index == -1)
+                goto done;
+
+        if ((class = crypto_ex_data_class_lookup(class_index)) == NULL)
+                goto done;
+
+        OPENSSL_assert(ced->class_index == class_index);
+
+        /* Existing indexes are immutable, we just have to know when to stop. */
+        CRYPTO_r_lock(CRYPTO_LOCK_EX_DATA);
+        last_index = class->next_index;
+        CRYPTO_r_unlock(CRYPTO_LOCK_EX_DATA);
+
+        for (i = 0; i < last_index; i++) {
+                if ((index = class->indexes[i]) == NULL)
+                        continue;
+                if (index->free_func == NULL)
+                        continue;
+                index->free_func(parent, ced->slots[i], exdata, i, index->argl,
+                    index->argp);
+        }
+
+ done:
+        crypto_ex_data_clear(exdata);
+}
+LCRYPTO_ALIAS(CRYPTO_free_ex_data);
+
+int
+CRYPTO_set_ex_data(CRYPTO_EX_DATA *exdata, int idx, void *val)
+{
+        struct crypto_ex_data *ced;
+
+        /*
+         * Preserve horrible historical behaviour - allow set to work even if
+         * new has not been called first.
+         */
+        if ((ced = exdata->sk) == NULL) {
+                if (!crypto_ex_data_init(exdata))
+                        return 0;
+                ced = exdata->sk;
+        }
+
+        /* XXX - consider preventing set for an unallocated index. */
+
+        if (idx < 0 || idx >= ced->slots_len)
+                return 0;
+
+        ced->slots[idx] = val;
+
+        return 1;
+}
+LCRYPTO_ALIAS(CRYPTO_set_ex_data);
+
+void *
+CRYPTO_get_ex_data(const CRYPTO_EX_DATA *exdata, int idx)
+{
+        struct crypto_ex_data *ced;
+
+        if ((ced = exdata->sk) == NULL)
+                return NULL;
+        if (idx < 0 || idx >= ced->slots_len)
+                return NULL;
+
+        return ced->slots[idx];
+}
+LCRYPTO_ALIAS(CRYPTO_get_ex_data);