Re: [PATCH v3 1/9] crypto: introduce decompression API that can be called via sharable tfm object

From: Sergey Senozhatsky
Date: Mon Sep 21 2015 - 01:38:18 EST


On (09/18/15 14:19), Joonsoo Kim wrote:
[..]
> @@ -61,7 +61,8 @@ static struct crypto_alg alg = {
> .cra_module = THIS_MODULE,
> .cra_u = { .compress = {
> .coa_compress = crypto842_compress,
> - .coa_decompress = crypto842_decompress } }
> + .coa_decompress = crypto842_decompress,
> + .coa_decompress_noctx = NULL } }
> };
>
> static int __init crypto842_mod_init(void)
> diff --git a/crypto/compress.c b/crypto/compress.c
> index c33f076..abb36a8 100644
> --- a/crypto/compress.c
> +++ b/crypto/compress.c
> @@ -33,12 +33,21 @@ static int crypto_decompress(struct crypto_tfm *tfm,
> dlen);
> }
>
> +static int crypto_decompress_noctx(struct crypto_tfm *tfm,
> + const u8 *src, unsigned int slen,
> + u8 *dst, unsigned int *dlen)
> +{
> + return tfm->__crt_alg->cra_compress.coa_decompress_noctx(src, slen,
> + dst, dlen);
> +}


hm... well... sorry, if irrelevant.
if the algorithm can have a _noctx() decompression function, does it
automatically guarantee that this algorithm never dereferences a passed
`struct crypto_tfm *tfm' pointer in its decompress function? in other words,
can we simply pass that `shared tfm pointer' to the existing decompress
function instead of defining new symbols, new callbacks, etc.?

cot_decompress_noctx() == cot_decompress(shared_ftm) ?

just a thought.

[..]
> +struct crypto_comp *crypto_alloc_comp_noctx(const char *alg_name,
> + u32 type, u32 mask)
> +{
> + struct crypto_comp *comp;
> + struct crypto_tfm *tfm;
> + struct compress_tfm *ops;
> +
> + comp = crypto_alloc_comp(alg_name, type, mask);
> + if (IS_ERR(comp))
> + return comp;
> +
> + tfm = crypto_comp_tfm(comp);
> + if (!tfm->__crt_alg->cra_compress.coa_decompress_noctx) {
> + crypto_free_comp(comp);
> + return ERR_PTR(-EINVAL);

-ENOMEM?

-ss
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