crypto: crypto_null - Drop unused cipher_null crypto_alg

The cipher_null crypto_alg cipher is never used in a meaningful way,
given that it is always wrapped in ecb(), which has its own dedicated
implementation. IOW, the cipher_null crypto_alg should never be used to
implement the ecb(cipher_null) skcipher, and using it for other things
is bogus.

However, it is accessible from user space, and due to the nature of the
AF_ALG interface, it may be wrapped in arbitrary ways, exposing issues
in template code that wasn't written with block ciphers with a block
size of '1' in mind.

So drop this code.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/crypto_null.c b/crypto/crypto_null.c
index 34588f39fdfc63181a5224ee00ca8fb9009fb4ea..fea151df1648a1a96615974146e24ccc165d9f1a 100644 (file)
--- a/crypto/crypto_null.c
+++ b/crypto/crypto_null.c
@@ -50,15 +50,6 @@ static int null_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
                                unsigned int keylen)
 { return 0; }
 
-static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
-                      unsigned int keylen)
-{ return 0; }
-
-static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
-{
-       memcpy(dst, src, NULL_BLOCK_SIZE);
-}
-
 static int null_skcipher_crypt(struct skcipher_request *req)
 {
        if (req->src != req->dst)
@@ -97,35 +88,16 @@ static struct skcipher_alg skcipher_null = {
        .decrypt                =       null_skcipher_crypt,
 };
 
-static struct crypto_alg cipher_null = {
-       .cra_name               =       "cipher_null",
-       .cra_driver_name        =       "cipher_null-generic",
-       .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
-       .cra_blocksize          =       NULL_BLOCK_SIZE,
-       .cra_ctxsize            =       0,
-       .cra_module             =       THIS_MODULE,
-       .cra_u                  =       { .cipher = {
-       .cia_min_keysize        =       NULL_KEY_SIZE,
-       .cia_max_keysize        =       NULL_KEY_SIZE,
-       .cia_setkey             =       null_setkey,
-       .cia_encrypt            =       null_crypt,
-       .cia_decrypt            =       null_crypt } }
-};
-
 MODULE_ALIAS_CRYPTO("digest_null");
-MODULE_ALIAS_CRYPTO("cipher_null");
+MODULE_ALIAS_CRYPTO("ecb(cipher_null)");
 
 static int __init crypto_null_mod_init(void)
 {
        int ret = 0;
 
-       ret = crypto_register_alg(&cipher_null);
-       if (ret < 0)
-               goto out;
-
        ret = crypto_register_shash(&digest_null);
        if (ret < 0)
-               goto out_unregister_algs;
+               goto out;
 
        ret = crypto_register_skcipher(&skcipher_null);
        if (ret < 0)
@@ -135,15 +107,12 @@ static int __init crypto_null_mod_init(void)
 
 out_unregister_shash:
        crypto_unregister_shash(&digest_null);
-out_unregister_algs:
-       crypto_unregister_alg(&cipher_null);
 out:
        return ret;
 }
 
 static void __exit crypto_null_mod_fini(void)
 {
-       crypto_unregister_alg(&cipher_null);
        crypto_unregister_shash(&digest_null);
        crypto_unregister_skcipher(&skcipher_null);
 }