Messages in this thread | | | Date | Thu, 16 Aug 2012 16:39:51 -0500 | From | Serge Hallyn <> | Subject | Re: [RFC v2 1/7] integrity: added digest calculation function |
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Quoting Kasatkin, Dmitry (dmitry.kasatkin@intel.com): > On Thu, Aug 16, 2012 at 12:11 AM, Kasatkin, Dmitry > <dmitry.kasatkin@intel.com> wrote: > > On Wed, Aug 15, 2012 at 11:11 PM, Serge Hallyn > > <serge.hallyn@canonical.com> wrote: > >> 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. > >> > > > > Intention was to allocate it only if tfm allocation succeeded.. > > But indeed failure very unlikely.. > > > > BTW.. The reason for such code is that ctx member uses function in the > parameter: > > char ctx[crypto_shash_descsize(tfm)]; > > It is not possible to do it before tfm allocation... > So I cannot move it up..
Ah, I see. Cool :)
> I can only kmalloc it then.
Well no, you could use another function I suppose.
But if you're going to leave it as is, please at least move the whole rest of the function into the else{} :) Yes, no functional change, but a change in how it looks to the eye of someone trying to review and look for actual free-unallocated-memory errors or leaks.
-serge
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