[CRYPTO] api: Added spawns

Spawns lock a specific crypto algorithm in place.  They can then be used
with crypto_spawn_tfm to allocate a tfm for that algorithm.  When the base
algorithm of a spawn is deregistered, all its spawns will be automatically
removed.

Signed-off-by: Herbert Xu <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: herbertx

crypto/algapi.c

@@ -10,6 +10,7 @@
  *
  */
 
+#include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -73,27 +74,96 @@ static int crypto_check_alg(struct crypto_alg *alg)
 	return crypto_set_driver_name(alg);
 }
 
-static int __crypto_register_alg(struct crypto_alg *alg)
+static void crypto_destroy_instance(struct crypto_alg *alg)
+{
+	struct crypto_instance *inst = (void *)alg;
+	struct crypto_template *tmpl = inst->tmpl;
+
+	tmpl->free(inst);
+	crypto_tmpl_put(tmpl);
+}
+
+static void crypto_remove_spawns(struct list_head *spawns,
+				 struct list_head *list)
+{
+	struct crypto_spawn *spawn, *n;
+
+	list_for_each_entry_safe(spawn, n, spawns, list) {
+		struct crypto_instance *inst = spawn->inst;
+		struct crypto_template *tmpl = inst->tmpl;
+
+		list_del_init(&spawn->list);
+		spawn->alg = NULL;
+
+		if (crypto_is_dead(&inst->alg))
+			continue;
+
+		inst->alg.cra_flags |= CRYPTO_ALG_DEAD;
+		if (!tmpl || !crypto_tmpl_get(tmpl))
+			continue;
+
+		crypto_notify(CRYPTO_MSG_ALG_UNREGISTER, &inst->alg);
+		list_move(&inst->alg.cra_list, list);
+		hlist_del(&inst->list);
+		inst->alg.cra_destroy = crypto_destroy_instance;
+
+		if (!list_empty(&inst->alg.cra_users)) {
+			if (&n->list == spawns)
+				n = list_entry(inst->alg.cra_users.next,
+					       typeof(*n), list);
+			__list_splice(&inst->alg.cra_users, spawns->prev);
+		}
+	}
+}
+
+static int __crypto_register_alg(struct crypto_alg *alg,
+				 struct list_head *list)
 {
 	struct crypto_alg *q;
-	int ret = -EEXIST;
+	int ret = -EAGAIN;
+
+	if (crypto_is_dead(alg))
+		goto out;
+
+	INIT_LIST_HEAD(&alg->cra_users);
+
+	ret = -EEXIST;
 
 	atomic_set(&alg->cra_refcnt, 1);
 	list_for_each_entry(q, &crypto_alg_list, cra_list) {
 		if (q == alg)
 			goto out;
-		if (crypto_is_larval(q) &&
-		    (!strcmp(alg->cra_name, q->cra_name) ||
-		     !strcmp(alg->cra_driver_name, q->cra_name))) {
+
+		if (crypto_is_moribund(q))
+			continue;
+
+		if (crypto_is_larval(q)) {
 			struct crypto_larval *larval = (void *)q;
 
+			if (strcmp(alg->cra_name, q->cra_name) &&
+			    strcmp(alg->cra_driver_name, q->cra_name))
+				continue;
+
+			if (larval->adult)
+				continue;
 			if ((q->cra_flags ^ alg->cra_flags) & larval->mask)
 				continue;
 			if (!crypto_mod_get(alg))
 				continue;
+
 			larval->adult = alg;
 			complete(&larval->completion);
+			continue;
 		}
+
+		if (strcmp(alg->cra_name, q->cra_name))
+			continue;
+
+		if (strcmp(alg->cra_driver_name, q->cra_driver_name) &&
+		    q->cra_priority > alg->cra_priority)
+			continue;
+
+		crypto_remove_spawns(&q->cra_users, list);
 	}
 
 	list_add(&alg->cra_list, &crypto_alg_list);
@@ -105,32 +175,56 @@ static int __crypto_register_alg(struct crypto_alg *alg)
 	return ret;
 }
 
+static void crypto_remove_final(struct list_head *list)
+{
+	struct crypto_alg *alg;
+	struct crypto_alg *n;
+
+	list_for_each_entry_safe(alg, n, list, cra_list) {
+		list_del_init(&alg->cra_list);
+		crypto_alg_put(alg);
+	}
+}
+
 int crypto_register_alg(struct crypto_alg *alg)
 {
+	LIST_HEAD(list);
 	int err;
 
 	err = crypto_check_alg(alg);
 	if (err)
 		return err;
 
 	down_write(&crypto_alg_sem);
-	err = __crypto_register_alg(alg);
+	err = __crypto_register_alg(alg, &list);
 	up_write(&crypto_alg_sem);
 
+	crypto_remove_final(&list);
 	return err;
 }
 EXPORT_SYMBOL_GPL(crypto_register_alg);
 
+static int crypto_remove_alg(struct crypto_alg *alg, struct list_head *list)
+{
+	if (unlikely(list_empty(&alg->cra_list)))
+		return -ENOENT;
+
+	alg->cra_flags |= CRYPTO_ALG_DEAD;
+
+	crypto_notify(CRYPTO_MSG_ALG_UNREGISTER, alg);
+	list_del_init(&alg->cra_list);
+	crypto_remove_spawns(&alg->cra_users, list);
+
+	return 0;
+}
+
 int crypto_unregister_alg(struct crypto_alg *alg)
 {
-	int ret = -ENOENT;
+	int ret;
+	LIST_HEAD(list);
 
 	down_write(&crypto_alg_sem);
-	if (likely(!list_empty(&alg->cra_list))) {
-		list_del_init(&alg->cra_list);
-		ret = 0;
-	}
-	crypto_notify(CRYPTO_MSG_ALG_UNREGISTER, alg);
+	ret = crypto_remove_alg(alg, &list);
 	up_write(&crypto_alg_sem);
 
 	if (ret)
@@ -140,6 +234,7 @@ int crypto_unregister_alg(struct crypto_alg *alg)
 	if (alg->cra_destroy)
 		alg->cra_destroy(alg);
 
+	crypto_remove_final(&list);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(crypto_unregister_alg);
@@ -170,6 +265,7 @@ void crypto_unregister_template(struct crypto_template *tmpl)
 	struct crypto_instance *inst;
 	struct hlist_node *p, *n;
 	struct hlist_head *list;
+	LIST_HEAD(users);
 
 	down_write(&crypto_alg_sem);
 
@@ -178,9 +274,8 @@ void crypto_unregister_template(struct crypto_template *tmpl)
 
 	list = &tmpl->instances;
 	hlist_for_each_entry(inst, p, list, list) {
-		BUG_ON(list_empty(&inst->alg.cra_list));
-		list_del_init(&inst->alg.cra_list);
-		crypto_notify(CRYPTO_MSG_ALG_UNREGISTER, &inst->alg);
+		int err = crypto_remove_alg(&inst->alg, &users);
+		BUG_ON(err);
 	}
 
 	crypto_notify(CRYPTO_MSG_TMPL_UNREGISTER, tmpl);
@@ -191,6 +286,7 @@ void crypto_unregister_template(struct crypto_template *tmpl)
 		BUG_ON(atomic_read(&inst->alg.cra_refcnt) != 1);
 		tmpl->free(inst);
 	}
+	crypto_remove_final(&users);
 }
 EXPORT_SYMBOL_GPL(crypto_unregister_template);
 
@@ -222,6 +318,7 @@ EXPORT_SYMBOL_GPL(crypto_lookup_template);
 int crypto_register_instance(struct crypto_template *tmpl,
 			     struct crypto_instance *inst)
 {
+	LIST_HEAD(list);
 	int err = -EINVAL;
 
 	if (inst->alg.cra_destroy)
@@ -235,7 +332,7 @@ int crypto_register_instance(struct crypto_template *tmpl,
 
 	down_write(&crypto_alg_sem);
 
-	err = __crypto_register_alg(&inst->alg);
+	err = __crypto_register_alg(&inst->alg, &list);
 	if (err)
 		goto unlock;
 
@@ -245,11 +342,67 @@ int crypto_register_instance(struct crypto_template *tmpl,
 unlock:
 	up_write(&crypto_alg_sem);
 
+	crypto_remove_final(&list);
+
 err:
 	return err;
 }
 EXPORT_SYMBOL_GPL(crypto_register_instance);
 
+int crypto_init_spawn(struct crypto_spawn *spawn, struct crypto_alg *alg,
+		      struct crypto_instance *inst)
+{
+	int err = -EAGAIN;
+
+	spawn->inst = inst;
+
+	down_write(&crypto_alg_sem);
+	if (!crypto_is_moribund(alg)) {
+		list_add(&spawn->list, &alg->cra_users);
+		spawn->alg = alg;
+		err = 0;
+	}
+	up_write(&crypto_alg_sem);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(crypto_init_spawn);
+
+void crypto_drop_spawn(struct crypto_spawn *spawn)
+{
+	down_write(&crypto_alg_sem);
+	list_del(&spawn->list);
+	up_write(&crypto_alg_sem);
+}
+EXPORT_SYMBOL_GPL(crypto_drop_spawn);
+
+struct crypto_tfm *crypto_spawn_tfm(struct crypto_spawn *spawn)
+{
+	struct crypto_alg *alg;
+	struct crypto_alg *alg2;
+	struct crypto_tfm *tfm;
+
+	down_read(&crypto_alg_sem);
+	alg = spawn->alg;
+	alg2 = alg;
+	if (alg2)
+		alg2 = crypto_mod_get(alg2);
+	up_read(&crypto_alg_sem);
+
+	if (!alg2) {
+		if (alg)
+			crypto_shoot_alg(alg);
+		return ERR_PTR(-EAGAIN);
+	}
+
+	tfm = __crypto_alloc_tfm(alg, 0);
+	if (IS_ERR(tfm))
+		crypto_mod_put(alg);
+
+	return tfm;
+}
+EXPORT_SYMBOL_GPL(crypto_spawn_tfm);
+
 int crypto_register_notifier(struct notifier_block *nb)
 {
 	return blocking_notifier_chain_register(&crypto_chain, nb);