Replumbing: add fallback provider capability
[openssl.git] / crypto / provider_core.c
index 8af5b1f14da15189cd9aef36503ecb941b73e415..c136e42e16e48161542c950db18d81bf83717359 100644 (file)
@@ -25,6 +25,7 @@ struct provider_store_st;        /* Forward declaration */
 struct ossl_provider_st {
     /* Flag bits */
     unsigned int flag_initialized:1;
+    unsigned int flag_fallback:1;
 
     /* OpenSSL library side data */
     CRYPTO_REF_COUNT refcnt;
@@ -32,6 +33,7 @@ struct ossl_provider_st {
     char *name;
     DSO *module;
     OSSL_provider_init_fn *init_function;
+    struct provider_store_st *store; /* The store this instance belongs to */
 
     /* Provider side functions */
     OSSL_provider_teardown_fn *teardown;
@@ -58,6 +60,7 @@ static int ossl_provider_cmp(const OSSL_PROVIDER * const *a,
 struct provider_store_st {
     STACK_OF(OSSL_PROVIDER) *providers;
     CRYPTO_RWLOCK *lock;
+    unsigned int use_fallbacks:1;
 };
 static int provider_store_index = -1;
 
@@ -80,8 +83,9 @@ static void *provider_store_new(void)
         || (store->providers = sk_OSSL_PROVIDER_new(ossl_provider_cmp)) == NULL
         || (store->lock = CRYPTO_THREAD_lock_new()) == NULL) {
         provider_store_free(store);
-        store = NULL;
+        return NULL;
     }
+    store->use_fallbacks = 1;
     return store;
 }
 
@@ -185,6 +189,8 @@ OSSL_PROVIDER *ossl_provider_new(OPENSSL_CTX *libctx, const char *name,
         ossl_provider_free(prov); /* -1 Store reference */
         ossl_provider_free(prov); /* -1 Reference that was to be returned */
         prov = NULL;
+    } else {
+        prov->store = store;
     }
     CRYPTO_THREAD_unlock(store->lock);
 
@@ -207,11 +213,13 @@ void ossl_provider_free(OSSL_PROVIDER *prov)
         CRYPTO_DOWN_REF(&prov->refcnt, &ref, prov->refcnt_lock);
 
         /*
-         * When the refcount drops down to one, there is only one reference,
-         * the store.
+         * When the refcount drops below two, the store is the only
+         * possible reference, or it has already been taken away from
+         * the store (this may happen if a provider was activated
+         * because it's a fallback, but isn't currently used)
          * When that happens, the provider is inactivated.
          */
-        if (ref == 1 && prov->flag_initialized) {
+        if (ref < 2 && prov->flag_initialized) {
             if (prov->teardown != NULL)
                 prov->teardown();
             prov->flag_initialized = 0;
@@ -246,7 +254,12 @@ void ossl_provider_free(OSSL_PROVIDER *prov)
  */
 static const OSSL_DISPATCH *core_dispatch; /* Define further down */
 
-int ossl_provider_activate(OSSL_PROVIDER *prov)
+/*
+ * Internal version that doesn't affect the store flags, and thereby avoid
+ * locking.  Direct callers must remember to set the store flags when
+ * appropriate
+ */
+static int provider_activate(OSSL_PROVIDER *prov)
 {
     const OSSL_DISPATCH *provider_dispatch = NULL;
 
@@ -295,7 +308,7 @@ int ossl_provider_activate(OSSL_PROVIDER *prov)
 
     if (prov->init_function == NULL
         || !prov->init_function(prov, core_dispatch, &provider_dispatch)) {
-        CRYPTOerr(CRYPTO_F_OSSL_PROVIDER_ACTIVATE, ERR_R_INIT_FAIL);
+        CRYPTOerr(CRYPTO_F_PROVIDER_ACTIVATE, ERR_R_INIT_FAIL);
         ERR_add_error_data(2, "name=", prov->name);
         DSO_free(prov->module);
         prov->module = NULL;
@@ -329,6 +342,46 @@ int ossl_provider_activate(OSSL_PROVIDER *prov)
     return 1;
 }
 
+int ossl_provider_activate(OSSL_PROVIDER *prov)
+{
+    if (provider_activate(prov)) {
+        CRYPTO_THREAD_write_lock(prov->store->lock);
+        prov->store->use_fallbacks = 0;
+        CRYPTO_THREAD_unlock(prov->store->lock);
+        return 1;
+    }
+
+    return 0;
+}
+
+
+static int provider_forall_loaded(struct provider_store_st *store,
+                                  int *found_activated,
+                                  int (*cb)(OSSL_PROVIDER *provider,
+                                            void *cbdata),
+                                  void *cbdata)
+{
+    int i;
+    int ret = 1;
+    int num_provs = sk_OSSL_PROVIDER_num(store->providers);
+
+    if (found_activated != NULL)
+        *found_activated = 0;
+    for (i = 0; i < num_provs; i++) {
+        OSSL_PROVIDER *prov =
+            sk_OSSL_PROVIDER_value(store->providers, i);
+
+        if (prov->flag_initialized) {
+            if (found_activated != NULL)
+                *found_activated = 1;
+            if (!(ret = cb(prov, cbdata)))
+                break;
+        }
+    }
+
+    return ret;
+}
+
 int ossl_provider_forall_loaded(OPENSSL_CTX *ctx,
                                 int (*cb)(OSSL_PROVIDER *provider,
                                           void *cbdata),
@@ -339,13 +392,50 @@ int ossl_provider_forall_loaded(OPENSSL_CTX *ctx,
     struct provider_store_st *store = get_provider_store(ctx);
 
     if (store != NULL) {
+        int found_activated = 0;
+
         CRYPTO_THREAD_read_lock(store->lock);
-        for (i = 0; i < sk_OSSL_PROVIDER_num(store->providers); i++) {
-            OSSL_PROVIDER *prov = sk_OSSL_PROVIDER_value(store->providers, i);
+        ret = provider_forall_loaded(store, &found_activated, cb, cbdata);
 
-            if (prov->flag_initialized
-                && !(ret = cb(prov, cbdata)))
-                break;
+        /*
+         * If there's nothing activated ever in this store, try to activate
+         * all fallbacks.
+         */
+        if (!found_activated && store->use_fallbacks) {
+            int num_provs = sk_OSSL_PROVIDER_num(store->providers);
+            int activated_fallback_count = 0;
+
+            for (i = 0; i < num_provs; i++) {
+                OSSL_PROVIDER *prov =
+                    sk_OSSL_PROVIDER_value(store->providers, i);
+
+                /*
+                 * Note that we don't care if the activation succeeds or
+                 * not.  If it doesn't succeed, then the next loop will
+                 * fail anyway.
+                 */
+                if (prov->flag_fallback) {
+                    activated_fallback_count++;
+                    provider_activate(prov);
+                }
+            }
+
+            if (activated_fallback_count > 0) {
+                /*
+                 * We assume that all fallbacks have been added to the store
+                 * before any fallback is activated.
+                 * TODO: We may have to reconsider this, IF we find ourselves
+                 * adding fallbacks after any previous fallback has been
+                 * activated.
+                 */
+                store->use_fallbacks = 0;
+
+                /*
+                 * Now that we've activated available fallbacks, try a
+                 * second sweep
+                 */
+                ret = provider_forall_loaded(store, NULL, cb, cbdata);
+            }
         }
         CRYPTO_THREAD_unlock(store->lock);
     }
@@ -353,6 +443,16 @@ int ossl_provider_forall_loaded(OPENSSL_CTX *ctx,
     return ret;
 }
 
+/* Setters of Provider Object data */
+int ossl_provider_set_fallback(OSSL_PROVIDER *prov)
+{
+    if (prov == NULL)
+        return 0;
+
+    prov->flag_fallback = 1;
+    return 1;
+}
+
 /* Getters of Provider Object data */
 const char *ossl_provider_name(OSSL_PROVIDER *prov)
 {