crypto: skcipher - prevent using skciphers without setting key

Similar to what was done for the hash API, update the skcipher 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 as important as the equivalent fix for the hash API because
symmetric ciphers almost always require a key (the "null cipher" is the
only exception), so are unlikely to be used without one.  Still,
tracking the key will prevent accidental unkeyed use.  algif_skcipher
also had to track the key anyway, so the new flag replaces that and
simplifies the algif_skcipher implementation.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 6 insertions, 5 deletions

diff --git a/include/crypto/skcipher.h b/include/crypto/skcipher.h
index 562001cb412b..2f327f090c3e 100644
--- a/include/crypto/skcipher.h
+++ b/include/crypto/skcipher.h
@@ -401,11 +401,6 @@ static inline int crypto_skcipher_setkey(struct crypto_skcipher *tfm,
 	return tfm->setkey(tfm, key, keylen);
 }
 
-static inline bool crypto_skcipher_has_setkey(struct crypto_skcipher *tfm)
-{
-	return tfm->keysize;
-}
-
 static inline unsigned int crypto_skcipher_default_keysize(
 	struct crypto_skcipher *tfm)
 {
@@ -442,6 +437,9 @@ static inline int crypto_skcipher_encrypt(struct skcipher_request *req)
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 
+	if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
+		return -ENOKEY;
+
 	return tfm->encrypt(req);
 }
 
@@ -460,6 +458,9 @@ static inline int crypto_skcipher_decrypt(struct skcipher_request *req)
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 
+	if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
+		return -ENOKEY;
+
 	return tfm->decrypt(req);
 }