On Fri, Dec 06, 2019 at 02:41:55PM -0800, Eric Biggers wrote:
>
> This approach seems too error-prone, since the prototype of crypto_grab_aead()
> doesn't give any indication that it takes a reference to the algorithm which the
> caller *must* drop.
Fair point.
> How about returning the alg pointer in the last argument, similar to
> skcipher_alloc_instance_simple()? I know you sent a patch to remove that
> argument, but I think it's better to have it...
You probably guessed that I don't really like returning two objects
from the same function :)
So how about this: we let the Crypto API manage the refcount and
hide it from all the users. Something like this patch:
diff --git a/crypto/algapi.c b/crypto/algapi.c
index adb516380be9..34473ab992f2 100644
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -563,6 +563,7 @@ int crypto_register_instance(struct crypto_template *tmpl,
struct crypto_instance *inst)
{
struct crypto_larval *larval;
+ struct crypto_spawn *spawn;
int err;
err = crypto_check_alg(&inst->alg);
@@ -588,6 +589,9 @@ int crypto_register_instance(struct crypto_template *tmpl,
if (IS_ERR(larval))
goto err;
+ hlist_for_each_entry(spawn, &inst->spawn_list, spawn_list)
+ crypto_mod_put(spawn->alg);
+
crypto_wait_for_test(larval);
err = 0;
@@ -623,6 +627,7 @@ int crypto_init_spawn(struct crypto_spawn *spawn, struct crypto_alg *alg,
spawn->inst = inst;
spawn->mask = mask;
+ hlist_add_head(&spawn->spawn_list, &inst->spawn_list);
down_write(&crypto_alg_sem);
if (!crypto_is_moribund(alg)) {
@@ -674,6 +679,9 @@ void crypto_drop_spawn(struct crypto_spawn *spawn)
if (!spawn->dead)
list_del(&spawn->list);
up_write(&crypto_alg_sem);
+
+ if (hlist_unhashed(&spawn->inst->list))
+ crypto_mod_put(spawn->alg);
}
EXPORT_SYMBOL_GPL(crypto_drop_spawn);
diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
index 771a295ac755..284e96f2eda2 100644
--- a/include/crypto/algapi.h
+++ b/include/crypto/algapi.h
@@ -48,6 +48,7 @@ struct crypto_instance {
struct crypto_template *tmpl;
struct hlist_node list;
+ struct hlist_head spawn_list;
void *__ctx[] CRYPTO_MINALIGN_ATTR;
};
@@ -66,6 +67,7 @@ struct crypto_template {
struct crypto_spawn {
struct list_head list;
+ struct hlist_node spawn_list;
struct crypto_alg *alg;
struct crypto_instance *inst;
const struct crypto_type *frontend;
Thanks,
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
