Re: [RFC v2 1/7] integrity: added digest calculation function

[Serge Hallyn <serge.hallyn@canonical.com>]

Quoting Dmitry Kasatkin (dmitry.kasatkin@intel.com):
> There are several functions, that need to calculate digest.
> This patch adds common function for use by integrity subsystem.
> 
> Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
> ---
>  security/integrity/digsig.c    |   31 +++++++++++++++++++++++++++++--
>  security/integrity/integrity.h |    3 +++
>  2 files changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
> index 2dc167d..61a0c92 100644
> --- a/security/integrity/digsig.c
> +++ b/security/integrity/digsig.c
> @@ -13,9 +13,9 @@
>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>  
>  #include <linux/err.h>
> -#include <linux/rbtree.h>
>  #include <linux/key-type.h>
>  #include <linux/digsig.h>
> +#include <crypto/hash.h>
>  
>  #include "integrity.h"
>  
> @@ -28,7 +28,7 @@ static const char *keyring_name[INTEGRITY_KEYRING_MAX] = {
>  };
>  
>  int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
> -					const char *digest, int digestlen)
> +			    const char *digest, int digestlen)
>  {
>  	if (id >= INTEGRITY_KEYRING_MAX)
>  		return -EINVAL;
> @@ -46,3 +46,30 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
>  
>  	return digsig_verify(keyring[id], sig, siglen, digest, digestlen);
>  }
> +
> +int integrity_calc_digest(const char *algo, const void *data, const int len,
> +			  char *digest)
> +{
> +	int rc = -ENOMEM;
> +	struct crypto_shash *tfm;
> +
> +	tfm = crypto_alloc_shash(algo, 0, 0);
> +	if (IS_ERR(tfm)) {
> +		rc = PTR_ERR(tfm);
> +		pr_err("Can not allocate %s (reason: %d)\n", algo, rc);
> +		return rc;
> +	} else {
> +		struct {
> +			struct shash_desc shash;
> +			char ctx[crypto_shash_descsize(tfm)];
> +		} desc;

Needless confusing indentation here.  Just move the struct {} desc; to the
top and drop the else.  That will make it much more readable.

> +		desc.shash.tfm = tfm;
> +		desc.shash.flags = 0;
> +
> +		rc = crypto_shash_digest(&desc.shash, data, len, digest);
> +	}
> +
> +	crypto_free_shash(tfm);
> +	return rc;
> +}
> diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
> index e21362a..48ee2d4 100644
> --- a/security/integrity/integrity.h
> +++ b/security/integrity/integrity.h
> @@ -59,6 +59,9 @@ struct integrity_iint_cache *integrity_iint_find(struct inode *inode);
>  
>  #ifdef CONFIG_INTEGRITY_SIGNATURE
>  
> +int integrity_calc_digest(const char *algo, const void *data, const int len,
> +			  char *digest);
> +
>  int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
>  					const char *digest, int digestlen);
>  
> -- 
> 1.7.9.5
> 
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