crypto: ahash - Stop legacy tfms from using the set_virt fallback path

Ensure that drivers that have not been converted to the ahash API
do not use the ahash_request_set_virt fallback path as they cannot
use the software fallback.

Reported-by: Eric Biggers <[e-mail]>
Fixes: 9d7a0ab1c753 ("crypto: ahash - Handle partial blocks in API")
Signed-off-by: Herbert Xu <[e-mail]>

crypto/ahash.c

···
 	if (!crypto_ahash_need_fallback(tfm))
 		return -ENOSYS;
 
+	if (crypto_hash_no_export_core(tfm))
+		return -ENOSYS;
+
 	{
 		u8 state[HASH_MAX_STATESIZE];
 

include/crypto/internal/hash.h

···
 		!(alg->base.cra_flags & CRYPTO_ALG_OPTIONAL_KEY);
 }
 
+static inline bool crypto_hash_no_export_core(struct crypto_ahash *tfm)
+{
+	return crypto_hash_alg_common(tfm)->base.cra_flags &
+	       CRYPTO_AHASH_ALG_NO_EXPORT_CORE;
+}
+
 int crypto_grab_ahash(struct crypto_ahash_spawn *spawn,
 		      struct crypto_instance *inst,
 		      const char *name, u32 type, u32 mask);