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crypto: crypto_null - Drop unused cipher_null crypto_alg

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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>
This commit is contained in:
Ard Biesheuvel
2026-04-20 11:41:20 +02:00
committed by Herbert Xu
parent 58d0b2b907
commit cba5aebae1
1 changed files with 2 additions and 33 deletions
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35
crypto/crypto_null.c
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@@ -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);
}