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crypto: akcipher - default implementation for setting a private key

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Changes from v1:
  * removed the default implementation from set_pub_key: it is assumed that
    an implementation must always have this callback defined as there are
    no use case for an algorithm, which doesn't need a public key

Many akcipher implementations (like ECDSA) support only signature
verifications, so they don't have all callbacks defined.

Commit 78a0324f4a ("crypto: akcipher - default implementations for
request callbacks") introduced default callbacks for sign/verify
operations, which just return an error code.

However, these are not enough, because before calling sign the caller would
likely call set_priv_key first on the instantiated transform (as the
in-kernel testmgr does). This function does not have a default stub, so the
kernel crashes, when trying to set a private key on an akcipher, which
doesn't support signature generation.

I've noticed this, when trying to add a KAT vector for ECDSA signature to
the testmgr.

With this patch the testmgr returns an error in dmesg (as it should)
instead of crashing the kernel NULL ptr dereference.

Fixes: 78a0324f4a ("crypto: akcipher - default implementations for request callbacks")
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Ignat Korchagin 2022-08-31 19:37:06 +01:00 committed by Herbert Xu
parent dc377e013b
commit bc155c6c18
1 changed files with 8 additions and 0 deletions
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8
crypto/akcipher.c
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@ -120,6 +120,12 @@ static int akcipher_default_op(struct akcipher_request *req)
return -ENOSYS; return -ENOSYS;
} }
static int akcipher_default_set_key(struct crypto_akcipher *tfm,
const void *key, unsigned int keylen)
{
return -ENOSYS;
}
int crypto_register_akcipher(struct akcipher_alg *alg) int crypto_register_akcipher(struct akcipher_alg *alg)
{ {
struct crypto_alg *base = &alg->base; struct crypto_alg *base = &alg->base;
@ -132,6 +138,8 @@ int crypto_register_akcipher(struct akcipher_alg *alg)
alg->encrypt = akcipher_default_op; alg->encrypt = akcipher_default_op;
if (!alg->decrypt) if (!alg->decrypt)
alg->decrypt = akcipher_default_op; alg->decrypt = akcipher_default_op;
if (!alg->set_priv_key)
alg->set_priv_key = akcipher_default_set_key;
akcipher_prepare_alg(alg); akcipher_prepare_alg(alg);
return crypto_register_alg(base); return crypto_register_alg(base);