Messages in this thread | | | Date | Thu, 16 Aug 2012 23:32:03 +0300 | Subject | Re: [RFC v2 1/7] integrity: added digest calculation function | From | "Kasatkin, Dmitry" <> |
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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.. I can only kmalloc it then.
There are many places of such allocation on stack in the kernel code. sparse also complains. I know.. But it looks for me reasonable, as descriptor size is not big...
- Dmitry
> thanks. > >>> + 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 >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-security-module" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html
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