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

From: Serge Hallyn
Date: Wed Aug 15 2012 - 16:11:51 EST


Quoting Dmitry Kasatkin (dmitry.kasatkin@xxxxxxxxx):
> 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@xxxxxxxxx>
> ---
> 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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