crypto: hash - Added scatter list walking helper
This patch adds the walking helpers for hash algorithms akin to
those of block ciphers. This is a necessary step before we can
reimplement existing hash algorithms using the new ahash interface.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/ahash.c b/crypto/ahash.c
index e6e5906..27128f2 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -13,7 +13,8 @@
*
*/
-#include <crypto/algapi.h>
+#include <crypto/internal/hash.h>
+#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
@@ -23,6 +24,94 @@
#include "internal.h"
+static int hash_walk_next(struct crypto_hash_walk *walk)
+{
+ unsigned int alignmask = walk->alignmask;
+ unsigned int offset = walk->offset;
+ unsigned int nbytes = min(walk->entrylen,
+ ((unsigned int)(PAGE_SIZE)) - offset);
+
+ walk->data = crypto_kmap(walk->pg, 0);
+ walk->data += offset;
+
+ if (offset & alignmask)
+ nbytes = alignmask + 1 - (offset & alignmask);
+
+ walk->entrylen -= nbytes;
+ return nbytes;
+}
+
+static int hash_walk_new_entry(struct crypto_hash_walk *walk)
+{
+ struct scatterlist *sg;
+
+ sg = walk->sg;
+ walk->pg = sg_page(sg);
+ walk->offset = sg->offset;
+ walk->entrylen = sg->length;
+
+ if (walk->entrylen > walk->total)
+ walk->entrylen = walk->total;
+ walk->total -= walk->entrylen;
+
+ return hash_walk_next(walk);
+}
+
+int crypto_hash_walk_done(struct crypto_hash_walk *walk, int err)
+{
+ unsigned int alignmask = walk->alignmask;
+ unsigned int nbytes = walk->entrylen;
+
+ walk->data -= walk->offset;
+
+ if (nbytes && walk->offset & alignmask && !err) {
+ walk->offset += alignmask - 1;
+ walk->offset = ALIGN(walk->offset, alignmask + 1);
+ walk->data += walk->offset;
+
+ nbytes = min(nbytes,
+ ((unsigned int)(PAGE_SIZE)) - walk->offset);
+ walk->entrylen -= nbytes;
+
+ return nbytes;
+ }
+
+ crypto_kunmap(walk->data, 0);
+ crypto_yield(walk->flags);
+
+ if (err)
+ return err;
+
+ walk->offset = 0;
+
+ if (nbytes)
+ return hash_walk_next(walk);
+
+ if (!walk->total)
+ return 0;
+
+ walk->sg = scatterwalk_sg_next(walk->sg);
+
+ return hash_walk_new_entry(walk);
+}
+EXPORT_SYMBOL_GPL(crypto_hash_walk_done);
+
+int crypto_hash_walk_first(struct ahash_request *req,
+ struct crypto_hash_walk *walk)
+{
+ walk->total = req->nbytes;
+
+ if (!walk->total)
+ return 0;
+
+ walk->alignmask = crypto_ahash_alignmask(crypto_ahash_reqtfm(req));
+ walk->sg = req->src;
+ walk->flags = req->base.flags;
+
+ return hash_walk_new_entry(walk);
+}
+EXPORT_SYMBOL_GPL(crypto_hash_walk_first);
+
static int ahash_setkey_unaligned(struct crypto_ahash *tfm, const u8 *key,
unsigned int keylen)
{
