initial commit, 4.5 stable

thirdparty/mbedtls/library/ssl_cache.c

@@ -0,0 +1,410 @@
+/*
+ *  SSL session cache implementation
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+/*
+ * These session callbacks use a simple chained list
+ * to store and retrieve the session information.
+ */
+
+#include "common.h"
+
+#if defined(MBEDTLS_SSL_CACHE_C)
+
+#include "mbedtls/platform.h"
+
+#include "mbedtls/ssl_cache.h"
+#include "ssl_misc.h"
+#include "mbedtls/error.h"
+
+#include <string.h>
+
+void mbedtls_ssl_cache_init(mbedtls_ssl_cache_context *cache)
+{
+    memset(cache, 0, sizeof(mbedtls_ssl_cache_context));
+
+    cache->timeout = MBEDTLS_SSL_CACHE_DEFAULT_TIMEOUT;
+    cache->max_entries = MBEDTLS_SSL_CACHE_DEFAULT_MAX_ENTRIES;
+
+#if defined(MBEDTLS_THREADING_C)
+    mbedtls_mutex_init(&cache->mutex);
+#endif
+}
+
+MBEDTLS_CHECK_RETURN_CRITICAL
+static int ssl_cache_find_entry(mbedtls_ssl_cache_context *cache,
+                                unsigned char const *session_id,
+                                size_t session_id_len,
+                                mbedtls_ssl_cache_entry **dst)
+{
+    int ret = MBEDTLS_ERR_SSL_CACHE_ENTRY_NOT_FOUND;
+#if defined(MBEDTLS_HAVE_TIME)
+    mbedtls_time_t t = mbedtls_time(NULL);
+#endif
+    mbedtls_ssl_cache_entry *cur;
+
+    for (cur = cache->chain; cur != NULL; cur = cur->next) {
+#if defined(MBEDTLS_HAVE_TIME)
+        if (cache->timeout != 0 &&
+            (int) (t - cur->timestamp) > cache->timeout) {
+            continue;
+        }
+#endif
+
+        if (session_id_len != cur->session_id_len ||
+            memcmp(session_id, cur->session_id,
+                   cur->session_id_len) != 0) {
+            continue;
+        }
+
+        break;
+    }
+
+    if (cur != NULL) {
+        *dst = cur;
+        ret = 0;
+    }
+
+    return ret;
+}
+
+
+int mbedtls_ssl_cache_get(void *data,
+                          unsigned char const *session_id,
+                          size_t session_id_len,
+                          mbedtls_ssl_session *session)
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    mbedtls_ssl_cache_context *cache = (mbedtls_ssl_cache_context *) data;
+    mbedtls_ssl_cache_entry *entry;
+
+#if defined(MBEDTLS_THREADING_C)
+    if ((ret = mbedtls_mutex_lock(&cache->mutex)) != 0) {
+        return ret;
+    }
+#endif
+
+    ret = ssl_cache_find_entry(cache, session_id, session_id_len, &entry);
+    if (ret != 0) {
+        goto exit;
+    }
+
+    ret = mbedtls_ssl_session_load(session,
+                                   entry->session,
+                                   entry->session_len);
+    if (ret != 0) {
+        goto exit;
+    }
+
+    ret = 0;
+
+exit:
+#if defined(MBEDTLS_THREADING_C)
+    if (mbedtls_mutex_unlock(&cache->mutex) != 0) {
+        ret = MBEDTLS_ERR_THREADING_MUTEX_ERROR;
+    }
+#endif
+
+    return ret;
+}
+
+/* zeroize a cache entry */
+static void ssl_cache_entry_zeroize(mbedtls_ssl_cache_entry *entry)
+{
+    if (entry == NULL) {
+        return;
+    }
+
+    /* zeroize and free session structure */
+    if (entry->session != NULL) {
+        mbedtls_zeroize_and_free(entry->session, entry->session_len);
+    }
+
+    /* zeroize the whole entry structure */
+    mbedtls_platform_zeroize(entry, sizeof(mbedtls_ssl_cache_entry));
+}
+
+MBEDTLS_CHECK_RETURN_CRITICAL
+static int ssl_cache_pick_writing_slot(mbedtls_ssl_cache_context *cache,
+                                       unsigned char const *session_id,
+                                       size_t session_id_len,
+                                       mbedtls_ssl_cache_entry **dst)
+{
+#if defined(MBEDTLS_HAVE_TIME)
+    mbedtls_time_t t = mbedtls_time(NULL), oldest = 0;
+#endif /* MBEDTLS_HAVE_TIME */
+
+    mbedtls_ssl_cache_entry *old = NULL;
+    int count = 0;
+    mbedtls_ssl_cache_entry *cur, *last;
+
+    /* Check 1: Is there already an entry with the given session ID?
+     *
+     * If yes, overwrite it.
+     *
+     * If not, `count` will hold the size of the session cache
+     * at the end of this loop, and `last` will point to the last
+     * entry, both of which will be used later. */
+
+    last = NULL;
+    for (cur = cache->chain; cur != NULL; cur = cur->next) {
+        count++;
+        if (session_id_len == cur->session_id_len &&
+            memcmp(session_id, cur->session_id, cur->session_id_len) == 0) {
+            goto found;
+        }
+        last = cur;
+    }
+
+    /* Check 2: Is there an outdated entry in the cache?
+     *
+     * If so, overwrite it.
+     *
+     * If not, remember the oldest entry in `old` for later.
+     */
+
+#if defined(MBEDTLS_HAVE_TIME)
+    for (cur = cache->chain; cur != NULL; cur = cur->next) {
+        if (cache->timeout != 0 &&
+            (int) (t - cur->timestamp) > cache->timeout) {
+            goto found;
+        }
+
+        if (oldest == 0 || cur->timestamp < oldest) {
+            oldest = cur->timestamp;
+            old = cur;
+        }
+    }
+#endif /* MBEDTLS_HAVE_TIME */
+
+    /* Check 3: Is there free space in the cache? */
+
+    if (count < cache->max_entries) {
+        /* Create new entry */
+        cur = mbedtls_calloc(1, sizeof(mbedtls_ssl_cache_entry));
+        if (cur == NULL) {
+            return MBEDTLS_ERR_SSL_ALLOC_FAILED;
+        }
+
+        /* Append to the end of the linked list. */
+        if (last == NULL) {
+            cache->chain = cur;
+        } else {
+            last->next = cur;
+        }
+
+        goto found;
+    }
+
+    /* Last resort: The cache is full and doesn't contain any outdated
+     * elements. In this case, we evict the oldest one, judged by timestamp
+     * (if present) or cache-order. */
+
+#if defined(MBEDTLS_HAVE_TIME)
+    if (old == NULL) {
+        /* This should only happen on an ill-configured cache
+         * with max_entries == 0. */
+        return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
+    }
+#else /* MBEDTLS_HAVE_TIME */
+    /* Reuse first entry in chain, but move to last place. */
+    if (cache->chain == NULL) {
+        /* This should never happen */
+        return MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    }
+
+    old = cache->chain;
+    cache->chain = old->next;
+    old->next = NULL;
+    last->next = old;
+#endif /* MBEDTLS_HAVE_TIME */
+
+    /* Now `old` points to the oldest entry to be overwritten. */
+    cur = old;
+
+found:
+
+    /* If we're reusing an entry, free it first. */
+    if (cur->session != NULL) {
+        /* `ssl_cache_entry_zeroize` would break the chain,
+         * so we reuse `old` to record `next` temporarily. */
+        old = cur->next;
+        ssl_cache_entry_zeroize(cur);
+        cur->next = old;
+    }
+
+#if defined(MBEDTLS_HAVE_TIME)
+    cur->timestamp = t;
+#endif
+
+    *dst = cur;
+    return 0;
+}
+
+int mbedtls_ssl_cache_set(void *data,
+                          unsigned char const *session_id,
+                          size_t session_id_len,
+                          const mbedtls_ssl_session *session)
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    mbedtls_ssl_cache_context *cache = (mbedtls_ssl_cache_context *) data;
+    mbedtls_ssl_cache_entry *cur;
+
+    size_t session_serialized_len = 0;
+    unsigned char *session_serialized = NULL;
+
+#if defined(MBEDTLS_THREADING_C)
+    if ((ret = mbedtls_mutex_lock(&cache->mutex)) != 0) {
+        return ret;
+    }
+#endif
+
+    ret = ssl_cache_pick_writing_slot(cache,
+                                      session_id, session_id_len,
+                                      &cur);
+    if (ret != 0) {
+        goto exit;
+    }
+
+    /* Check how much space we need to serialize the session
+     * and allocate a sufficiently large buffer. */
+    ret = mbedtls_ssl_session_save(session, NULL, 0, &session_serialized_len);
+    if (ret != MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL) {
+        goto exit;
+    }
+
+    session_serialized = mbedtls_calloc(1, session_serialized_len);
+    if (session_serialized == NULL) {
+        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
+        goto exit;
+    }
+
+    /* Now serialize the session into the allocated buffer. */
+    ret = mbedtls_ssl_session_save(session,
+                                   session_serialized,
+                                   session_serialized_len,
+                                   &session_serialized_len);
+    if (ret != 0) {
+        goto exit;
+    }
+
+    if (session_id_len > sizeof(cur->session_id)) {
+        ret = MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
+        goto exit;
+    }
+    cur->session_id_len = session_id_len;
+    memcpy(cur->session_id, session_id, session_id_len);
+
+    cur->session = session_serialized;
+    cur->session_len = session_serialized_len;
+    session_serialized = NULL;
+
+    ret = 0;
+
+exit:
+#if defined(MBEDTLS_THREADING_C)
+    if (mbedtls_mutex_unlock(&cache->mutex) != 0) {
+        ret = MBEDTLS_ERR_THREADING_MUTEX_ERROR;
+    }
+#endif
+
+    if (session_serialized != NULL) {
+        mbedtls_zeroize_and_free(session_serialized, session_serialized_len);
+        session_serialized = NULL;
+    }
+
+    return ret;
+}
+
+int mbedtls_ssl_cache_remove(void *data,
+                             unsigned char const *session_id,
+                             size_t session_id_len)
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    mbedtls_ssl_cache_context *cache = (mbedtls_ssl_cache_context *) data;
+    mbedtls_ssl_cache_entry *entry;
+    mbedtls_ssl_cache_entry *prev;
+
+#if defined(MBEDTLS_THREADING_C)
+    if ((ret = mbedtls_mutex_lock(&cache->mutex)) != 0) {
+        return ret;
+    }
+#endif
+
+    ret = ssl_cache_find_entry(cache, session_id, session_id_len, &entry);
+    /* No valid entry found, exit with success */
+    if (ret != 0) {
+        ret = 0;
+        goto exit;
+    }
+
+    /* Now we remove the entry from the chain */
+    if (entry == cache->chain) {
+        cache->chain = entry->next;
+        goto free;
+    }
+    for (prev = cache->chain; prev->next != NULL; prev = prev->next) {
+        if (prev->next == entry) {
+            prev->next = entry->next;
+            break;
+        }
+    }
+
+free:
+    ssl_cache_entry_zeroize(entry);
+    mbedtls_free(entry);
+    ret = 0;
+
+exit:
+#if defined(MBEDTLS_THREADING_C)
+    if (mbedtls_mutex_unlock(&cache->mutex) != 0) {
+        ret = MBEDTLS_ERR_THREADING_MUTEX_ERROR;
+    }
+#endif
+
+    return ret;
+}
+
+#if defined(MBEDTLS_HAVE_TIME)
+void mbedtls_ssl_cache_set_timeout(mbedtls_ssl_cache_context *cache, int timeout)
+{
+    if (timeout < 0) {
+        timeout = 0;
+    }
+
+    cache->timeout = timeout;
+}
+#endif /* MBEDTLS_HAVE_TIME */
+
+void mbedtls_ssl_cache_set_max_entries(mbedtls_ssl_cache_context *cache, int max)
+{
+    if (max < 0) {
+        max = 0;
+    }
+
+    cache->max_entries = max;
+}
+
+void mbedtls_ssl_cache_free(mbedtls_ssl_cache_context *cache)
+{
+    mbedtls_ssl_cache_entry *cur, *prv;
+
+    cur = cache->chain;
+
+    while (cur != NULL) {
+        prv = cur;
+        cur = cur->next;
+
+        ssl_cache_entry_zeroize(prv);
+        mbedtls_free(prv);
+    }
+
+#if defined(MBEDTLS_THREADING_C)
+    mbedtls_mutex_free(&cache->mutex);
+#endif
+    cache->chain = NULL;
+}
+
+#endif /* MBEDTLS_SSL_CACHE_C */