Merge pull request #7217 from lpy4105/issue/6840/add-cache-entry-removal-api
ssl_cache: Add cache entry removal api
diff --git a/ChangeLog.d/add-cache-remove-api.txt b/ChangeLog.d/add-cache-remove-api.txt
new file mode 100644
index 0000000..950ff97
--- /dev/null
+++ b/ChangeLog.d/add-cache-remove-api.txt
@@ -0,0 +1,5 @@
+Features
+ * Add new API mbedtls_ssl_cache_remove for cache entry removal by
+ its session id.
+Security
+ * Zeroize SSL cache entries when they are freed.
diff --git a/include/mbedtls/ssl_cache.h b/include/mbedtls/ssl_cache.h
index 5cd1cd3..55dcf77 100644
--- a/include/mbedtls/ssl_cache.h
+++ b/include/mbedtls/ssl_cache.h
@@ -123,6 +123,23 @@
size_t session_id_len,
const mbedtls_ssl_session *session);
+/**
+ * \brief Remove the cache entry by the session ID
+ * (Thread-safe if MBEDTLS_THREADING_C is enabled)
+ *
+ * \param data The SSL cache context to use.
+ * \param session_id The pointer to the buffer holding the session ID
+ * associated to \p session.
+ * \param session_id_len The length of \p session_id in bytes.
+ *
+ * \return 0: The cache entry for session with provided ID
+ * is removed or does not exist.
+ * Otherwise: fail.
+ */
+int mbedtls_ssl_cache_remove(void *data,
+ unsigned char const *session_id,
+ size_t session_id_len);
+
#if defined(MBEDTLS_HAVE_TIME)
/**
* \brief Set the cache timeout
diff --git a/library/ssl_cache.c b/library/ssl_cache.c
index 7c16e10..048c21d 100644
--- a/library/ssl_cache.c
+++ b/library/ssl_cache.c
@@ -92,8 +92,8 @@
mbedtls_ssl_cache_entry *entry;
#if defined(MBEDTLS_THREADING_C)
- if (mbedtls_mutex_lock(&cache->mutex) != 0) {
- return 1;
+ if ((ret = mbedtls_mutex_lock(&cache->mutex)) != 0) {
+ return ret;
}
#endif
@@ -114,13 +114,30 @@
exit:
#if defined(MBEDTLS_THREADING_C)
if (mbedtls_mutex_unlock(&cache->mutex) != 0) {
- ret = 1;
+ 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_platform_zeroize(entry->session, entry->session_len);
+ mbedtls_free(entry->session);
+ }
+
+ /* 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,
@@ -220,19 +237,19 @@
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
- /* If we're reusing an entry, free it first. */
- if (cur->session != NULL) {
- mbedtls_free(cur->session);
- cur->session = NULL;
- cur->session_len = 0;
- memset(cur->session_id, 0, sizeof(cur->session_id));
- cur->session_id_len = 0;
- }
-
*dst = cur;
return 0;
}
@@ -301,7 +318,7 @@
exit:
#if defined(MBEDTLS_THREADING_C)
if (mbedtls_mutex_unlock(&cache->mutex) != 0) {
- ret = 1;
+ ret = MBEDTLS_ERR_THREADING_MUTEX_ERROR;
}
#endif
@@ -314,6 +331,55 @@
return ret;
}
+int mbedtls_ssl_cache_remove(void *data,
+ unsigned char const *session_id,
+ size_t session_id_len)
+{
+ int ret = 1;
+ 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)
{
@@ -344,7 +410,7 @@
prv = cur;
cur = cur->next;
- mbedtls_free(prv->session);
+ ssl_cache_entry_zeroize(prv);
mbedtls_free(prv);
}
diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index 88c2192..1c34861 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -129,6 +129,7 @@
#define DFL_TICKET_AEAD MBEDTLS_CIPHER_AES_256_GCM
#define DFL_CACHE_MAX -1
#define DFL_CACHE_TIMEOUT -1
+#define DFL_CACHE_REMOVE 0
#define DFL_SNI NULL
#define DFL_ALPN_STRING NULL
#define DFL_CURVES NULL
@@ -321,7 +322,8 @@
#if defined(MBEDTLS_SSL_CACHE_C)
#define USAGE_CACHE \
- " cache_max=%%d default: cache default (50)\n"
+ " cache_max=%%d default: cache default (50)\n" \
+ " cache_remove=%%d default: 0 (don't remove)\n"
#if defined(MBEDTLS_HAVE_TIME)
#define USAGE_CACHE_TIME \
" cache_timeout=%%d default: cache default (1d)\n"
@@ -669,6 +671,7 @@
#if defined(MBEDTLS_HAVE_TIME)
int cache_timeout; /* expiration delay of session cache entries*/
#endif
+ int cache_remove; /* enable / disable cache removement */
char *sni; /* string describing sni information */
const char *curves; /* list of supported elliptic curves */
const char *sig_algs; /* supported TLS 1.3 signature algorithms */
@@ -1731,6 +1734,7 @@
#if defined(MBEDTLS_HAVE_TIME)
opt.cache_timeout = DFL_CACHE_TIMEOUT;
#endif
+ opt.cache_remove = DFL_CACHE_REMOVE;
opt.sni = DFL_SNI;
opt.alpn_string = DFL_ALPN_STRING;
opt.curves = DFL_CURVES;
@@ -2144,7 +2148,12 @@
}
}
#endif
- else if (strcmp(p, "cookies") == 0) {
+ else if (strcmp(p, "cache_remove") == 0) {
+ opt.cache_remove = atoi(q);
+ if (opt.cache_remove < 0 || opt.cache_remove > 1) {
+ goto usage;
+ }
+ } else if (strcmp(p, "cookies") == 0) {
opt.cookies = atoi(q);
if (opt.cookies < -1 || opt.cookies > 1) {
goto usage;
@@ -4127,6 +4136,12 @@
mbedtls_printf(" done\n");
+#if defined(MBEDTLS_SSL_CACHE_C)
+ if (opt.cache_remove > 0) {
+ mbedtls_ssl_cache_remove(&cache, ssl.session->id, ssl.session->id_len);
+ }
+#endif
+
goto reset;
/*
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index e2b1e04..663f194 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -4142,6 +4142,22 @@
requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2
requires_config_enabled MBEDTLS_SSL_CACHE_C
+run_test "Session resume using cache: cache removed" \
+ "$P_SRV debug_level=3 tickets=0 cache_remove=1" \
+ "$P_CLI debug_level=3 tickets=0 reconnect=1" \
+ 0 \
+ -C "client hello, adding session ticket extension" \
+ -S "found session ticket extension" \
+ -S "server hello, adding session ticket extension" \
+ -C "found session_ticket extension" \
+ -C "parse new session ticket" \
+ -S "session successfully restored from cache" \
+ -S "session successfully restored from ticket" \
+ -S "a session has been resumed" \
+ -C "a session has been resumed"
+
+requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2
+requires_config_enabled MBEDTLS_SSL_CACHE_C
run_test "Session resume using cache: timeout > delay" \
"$P_SRV debug_level=3 tickets=0" \
"$P_CLI debug_level=3 tickets=0 reconnect=1 reco_delay=0" \