Re: [PATCH 1/3 v2] crypto: introduce the flag CRYPTO_ALG_ALLOCATES_MEMORY

Mikulas Patocka
2020-06-28T19:04:42Z

On Fri, 26 Jun 2020, Eric Biggers wrote:

> On Fri, Jun 26, 2020 at 12:16:33PM -0400, Mikulas Patocka wrote:
> > +/*
> > + * Pass these flags down through the crypto API.
> > + */
> > +#define CRYPTO_ALG_INHERITED_FLAGS (CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY)
>
> This comment is useless. How about:
>
> /*
> * When an algorithm uses another algorithm (e.g., if it's an instance of a
> * template), these are the flags that always get set on the "outer" algorithm
> * if any "inner" algorithm has them set. In some cases other flags are
> * inherited too; these are just the flags that are *always* inherited.
> */
> #define CRYPTO_ALG_INHERITED_FLAGS (CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY)
>
> Also I wonder about the case where the inner algorithm is a fallback rather than
> part of a template instance. This patch only handles templates, not fallbacks.
> Is that intentional? Isn't that technically a bug?

I'm not an expert in crypto internals, so I don't know. I'll send version
3 of this patch and I'd like to ask you or Herbert to fix it.

> > +
> > +/*
> > * Transform masks and values (for crt_flags).
> > */
> > #define CRYPTO_TFM_NEED_KEY 0x00000001
> > Index: linux-2.6/crypto/authenc.c
> > ===================================================================
> > --- linux-2.6.orig/crypto/authenc.c 2020-06-26 17:24:03.566417000 +0200
> > +++ linux-2.6/crypto/authenc.c 2020-06-26 17:24:03.566417000 +0200
> > @@ -388,7 +388,8 @@ static int crypto_authenc_create(struct
> > if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
> > return -EINVAL;
> >
> > - mask = crypto_requires_sync(algt->type, algt->mask);
> > + mask = crypto_requires_sync(algt->type, algt->mask) |
> > + crypto_requires_nomem(algt->type, algt->mask);
>
> As I suggested earlier, shouldn't there be a function that returns the mask for
> all inherited flags, rather than handling each flag individually?

Yes - I've created crypto_requires_inherited for this purpose.

> >
> > inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
> > if (!inst)
> > @@ -424,7 +425,7 @@ static int crypto_authenc_create(struct
> > goto err_free_inst;
> >
> > inst->alg.base.cra_flags = (auth_base->cra_flags |
> > - enc->base.cra_flags) & CRYPTO_ALG_ASYNC;
> > + enc->base.cra_flags) & CRYPTO_ALG_INHERITED_FLAGS;
>
> Strange indentation here. Likewise in most of the other files.

I was told that the code should be 80-characters wide.

> > Index: linux-2.6/crypto/xts.c
> > ===================================================================
> > --- linux-2.6.orig/crypto/xts.c 2020-06-26 17:24:03.566417000 +0200
> > +++ linux-2.6/crypto/xts.c 2020-06-26 17:24:03.566417000 +0200
> > @@ -415,7 +415,7 @@ static int create(struct crypto_template
> > } else
> > goto err_free_inst;
> >
> > - inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
> > + inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_INHERITED_FLAGS;
> > inst->alg.base.cra_priority = alg->base.cra_priority;
> > inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
> > inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
>
> Need to set the mask correctly in this file.

I don't know what do you mean.

> > Index: linux-2.6/crypto/adiantum.c
> > ===================================================================
> > --- linux-2.6.orig/crypto/adiantum.c 2020-06-26 17:24:03.566417000 +0200
> > +++ linux-2.6/crypto/adiantum.c 2020-06-26 17:24:03.566417000 +0200
> > @@ -507,7 +507,8 @@ static int adiantum_create(struct crypto
> > if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
> > return -EINVAL;
> >
> > - mask = crypto_requires_sync(algt->type, algt->mask);
> > + mask = crypto_requires_sync(algt->type, algt->mask) |
> > + crypto_requires_nomem(algt->type, algt->mask);
> >
> > inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
> > if (!inst)
>
> Need to use CRYPTO_ALG_INHERITED_FLAGS in this file.

OK.

> - Eric

Mikulas