crypto: aead - prevent using AEADs without setting key

Similar to what was done for the hash API, update the AEAD API to track
whether each transform has been keyed, and reject encryption/decryption
if a key is needed but one hasn't been set.

This isn't quite as important as the equivalent fix for the hash API
because AEADs always require a key, so are unlikely to be used without
one.  Still, tracking the key will prevent accidental unkeyed use.
algif_aead also had to track the key anyway, so the new flag replaces
that and slightly simplifies the algif_aead implementation.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/aead.c b/crypto/aead.c
index fe00cbd..60b3bbe 100644
--- a/crypto/aead.c
+++ b/crypto/aead.c
@@ -54,11 +54,18 @@ int crypto_aead_setkey(struct crypto_aead *tfm,
 		       const u8 *key, unsigned int keylen)
 {
 	unsigned long alignmask = crypto_aead_alignmask(tfm);
+	int err;
 
 	if ((unsigned long)key & alignmask)
-		return setkey_unaligned(tfm, key, keylen);
+		err = setkey_unaligned(tfm, key, keylen);
+	else
+		err = crypto_aead_alg(tfm)->setkey(tfm, key, keylen);
 
-	return crypto_aead_alg(tfm)->setkey(tfm, key, keylen);
+	if (err)
+		return err;
+
+	crypto_aead_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(crypto_aead_setkey);
 
@@ -93,6 +100,8 @@ static int crypto_aead_init_tfm(struct crypto_tfm *tfm)
 	struct crypto_aead *aead = __crypto_aead_cast(tfm);
 	struct aead_alg *alg = crypto_aead_alg(aead);
 
+	crypto_aead_set_flags(aead, CRYPTO_TFM_NEED_KEY);
+
 	aead->authsize = alg->maxauthsize;
 
 	if (alg->exit)