crypto: api - Keep failed instances alive

herbertx · herbertx · commit eb02c38f0197 · 2018-03-31T01:32:58.000+08:00
This patch reverts commit 9c521a2 ("crypto: api - remove instance when test failed") and fixes the underlying problem in a different way. To recap, prior to the reverted commit, an instance that fails a self-test is kept around. However, it would satisfy any new lookups against its name and therefore the system may accumlulate an unbounded number of failed instances for the same algorithm name. The reverted commit fixed it by unregistering the instance. Hoever, this still does not prevent the creation of the same failed instance over and over again each time the name is looked up. This patch fixes it by keeping the failed instance around, just as we would if it were a normal algorithm. However, the lookup code has been udpated so that we do not attempt to create another instance as long as this failed one is still registered. Of course, you could still force a new creation by deleting the instance from user-space. A new error (ELIBBAD) has been commandeered for this purpose and will be returned when all registered algorithm of a given name have failed the self-test. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/algapi.c b/crypto/algapi.c
@@ -543,9 +543,6 @@ int crypto_register_instance(struct crypto_template *tmpl,
 	inst->alg.cra_module = tmpl->module;
 	inst->alg.cra_flags |= CRYPTO_ALG_INSTANCE;
 
-	if (unlikely(!crypto_mod_get(&inst->alg)))
-		return -EAGAIN;
-
 	down_write(&crypto_alg_sem);
 
 	larval = __crypto_register_alg(&inst->alg);
@@ -563,14 +560,9 @@ int crypto_register_instance(struct crypto_template *tmpl,
 		goto err;
 
 	crypto_wait_for_test(larval);
-
-	/* Remove instance if test failed */
-	if (!(inst->alg.cra_flags & CRYPTO_ALG_TESTED))
-		crypto_unregister_instance(inst);
 	err = 0;
 
 err:
-	crypto_mod_put(&inst->alg);
 	return err;
 }
 EXPORT_SYMBOL_GPL(crypto_register_instance);
diff --git a/crypto/api.c b/crypto/api.c
@@ -197,9 +197,16 @@ static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
 					    u32 mask)
 {
 	struct crypto_alg *alg;
+	u32 test = 0;
+
+	if (!((type | mask) & CRYPTO_ALG_TESTED))
+		test |= CRYPTO_ALG_TESTED;
 
 	down_read(&crypto_alg_sem);
-	alg = __crypto_alg_lookup(name, type, mask);
+	alg = __crypto_alg_lookup(name, type | test, mask | test);
+	if (!alg && test)
+		alg = __crypto_alg_lookup(name, type, mask) ?
+		      ERR_PTR(-ELIBBAD) : NULL;
 	up_read(&crypto_alg_sem);
 
 	return alg;
@@ -227,10 +234,12 @@ static struct crypto_alg *crypto_larval_lookup(const char *name, u32 type,
 		alg = crypto_alg_lookup(name, type, mask);
 	}
 
-	if (alg)
-		return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
+	if (!IS_ERR_OR_NULL(alg) && crypto_is_larval(alg))
+		alg = crypto_larval_wait(alg);
+	else if (!alg)
+		alg = crypto_larval_add(name, type, mask);
 
-	return crypto_larval_add(name, type, mask);
+	return alg;
 }
 
 int crypto_probing_notify(unsigned long val, void *v)
@@ -253,11 +262,6 @@ struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
 	struct crypto_alg *larval;
 	int ok;
 
-	if (!((type | mask) & CRYPTO_ALG_TESTED)) {
-		type |= CRYPTO_ALG_TESTED;
-		mask |= CRYPTO_ALG_TESTED;
-	}
-
 	/*
 	 * If the internal flag is set for a cipher, require a caller to
 	 * to invoke the cipher with the internal flag to use that cipher.
