crypto: ahash - remove support for nonzero alignmask

Currently, the ahash API checks the alignment of all key and result
buffers against the algorithm's declared alignmask, and for any
unaligned buffers it falls back to manually aligned temporary buffers.

This is virtually useless, however.  First, since it does not apply to
the message, its effect is much more limited than e.g. is the case for
the alignmask for "skcipher".  Second, the key and result buffers are
given as virtual addresses and cannot (in general) be DMA'ed into, so
drivers end up having to copy to/from them in software anyway.  As a
result it's easy to use memcpy() or the unaligned access helpers.

The crypto_hash_walk_*() helper functions do use the alignmask to align
the message.  But with one exception those are only used for shash
algorithms being exposed via the ahash API, not for native ahashes, and
aligning the message is not required in this case, especially now that
alignmask support has been removed from shash.  The exception is the
n2_core driver, which doesn't set an alignmask.

In any case, no ahash algorithms actually set a nonzero alignmask
anymore.  Therefore, remove support for it from ahash.  The benefit is
that all the code to handle "misaligned" buffers in the ahash API goes
away, reducing the overhead of the ahash API.

This follows the same change that was made to shash.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

2 files changed, 12 insertions, 113 deletions

diff --git a/crypto/ahash.c b/crypto/ahash.c
index 213bb3e9f245..744fd3b8ea25 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -35,21 +35,12 @@ struct ahash_request_priv {
 
 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 = kmap_local_page(walk->pg);
 	walk->data += offset;
-
-	if (offset & alignmask) {
-		unsigned int unaligned = alignmask + 1 - (offset & alignmask);
-
-		if (nbytes > unaligned)
-			nbytes = unaligned;
-	}
-
 	walk->entrylen -= nbytes;
 	return nbytes;
 }
@@ -73,23 +64,8 @@ static int hash_walk_new_entry(struct crypto_hash_walk *walk)
 
 int crypto_hash_walk_done(struct crypto_hash_walk *walk, int err)
 {
-	unsigned int alignmask = walk->alignmask;
-
 	walk->data -= walk->offset;
 
-	if (walk->entrylen && (walk->offset & alignmask) && !err) {
-		unsigned int nbytes;
-
-		walk->offset = ALIGN(walk->offset, alignmask + 1);
-		nbytes = min(walk->entrylen,
-			     (unsigned int)(PAGE_SIZE - walk->offset));
-		if (nbytes) {
-			walk->entrylen -= nbytes;
-			walk->data += walk->offset;
-			return nbytes;
-		}
-	}
-
 	kunmap_local(walk->data);
 	crypto_yield(walk->flags);
 
@@ -121,7 +97,6 @@ int crypto_hash_walk_first(struct ahash_request *req,
 		return 0;
 	}
 
-	walk->alignmask = crypto_ahash_alignmask(crypto_ahash_reqtfm(req));
 	walk->sg = req->src;
 	walk->flags = req->base.flags;
 
@@ -129,26 +104,6 @@ int crypto_hash_walk_first(struct ahash_request *req,
 }
 EXPORT_SYMBOL_GPL(crypto_hash_walk_first);
 
-static int ahash_setkey_unaligned(struct crypto_ahash *tfm, const u8 *key,
-				unsigned int keylen)
-{
-	unsigned long alignmask = crypto_ahash_alignmask(tfm);
-	int ret;
-	u8 *buffer, *alignbuffer;
-	unsigned long absize;
-
-	absize = keylen + alignmask;
-	buffer = kmalloc(absize, GFP_KERNEL);
-	if (!buffer)
-		return -ENOMEM;
-
-	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
-	memcpy(alignbuffer, key, keylen);
-	ret = tfm->setkey(tfm, alignbuffer, keylen);
-	kfree_sensitive(buffer);
-	return ret;
-}
-
 static int ahash_nosetkey(struct crypto_ahash *tfm, const u8 *key,
 			  unsigned int keylen)
 {
@@ -167,13 +122,7 @@ static void ahash_set_needkey(struct crypto_ahash *tfm)
 int crypto_ahash_setkey(struct crypto_ahash *tfm, const u8 *key,
 			unsigned int keylen)
 {
-	unsigned long alignmask = crypto_ahash_alignmask(tfm);
-	int err;
-
-	if ((unsigned long)key & alignmask)
-		err = ahash_setkey_unaligned(tfm, key, keylen);
-	else
-		err = tfm->setkey(tfm, key, keylen);
+	int err = tfm->setkey(tfm, key, keylen);
 
 	if (unlikely(err)) {
 		ahash_set_needkey(tfm);
@@ -189,7 +138,6 @@ static int ahash_save_req(struct ahash_request *req, crypto_completion_t cplt,
 			  bool has_state)
 {
 	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
-	unsigned long alignmask = crypto_ahash_alignmask(tfm);
 	unsigned int ds = crypto_ahash_digestsize(tfm);
 	struct ahash_request *subreq;
 	unsigned int subreq_size;
@@ -203,7 +151,6 @@ static int ahash_save_req(struct ahash_request *req, crypto_completion_t cplt,
 	reqsize = ALIGN(reqsize, crypto_tfm_ctx_alignment());
 	subreq_size += reqsize;
 	subreq_size += ds;
-	subreq_size += alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 
 	flags = ahash_request_flags(req);
 	gfp = (flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?  GFP_KERNEL : GFP_ATOMIC;
@@ -215,7 +162,6 @@ static int ahash_save_req(struct ahash_request *req, crypto_completion_t cplt,
 	ahash_request_set_callback(subreq, flags, cplt, req);
 
 	result = (u8 *)(subreq + 1) + reqsize;
-	result = PTR_ALIGN(result, alignmask + 1);
 
 	ahash_request_set_crypt(subreq, req->src, result, req->nbytes);
 
@@ -251,56 +197,6 @@ static void ahash_restore_req(struct ahash_request *req, int err)
 	kfree_sensitive(subreq);
 }
 
-static void ahash_op_unaligned_done(void *data, int err)
-{
-	struct ahash_request *areq = data;
-
-	if (err == -EINPROGRESS)
-		goto out;
-
-	/* First copy req->result into req->priv.result */
-	ahash_restore_req(areq, err);
-
-out:
-	/* Complete the ORIGINAL request. */
-	ahash_request_complete(areq, err);
-}
-
-static int ahash_op_unaligned(struct ahash_request *req,
-			      int (*op)(struct ahash_request *),
-			      bool has_state)
-{
-	int err;
-
-	err = ahash_save_req(req, ahash_op_unaligned_done, has_state);
-	if (err)
-		return err;
-
-	err = op(req->priv);
-	if (err == -EINPROGRESS || err == -EBUSY)
-		return err;
-
-	ahash_restore_req(req, err);
-
-	return err;
-}
-
-static int crypto_ahash_op(struct ahash_request *req,
-			   int (*op)(struct ahash_request *),
-			   bool has_state)
-{
-	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
-	unsigned long alignmask = crypto_ahash_alignmask(tfm);
-	int err;
-
-	if ((unsigned long)req->result & alignmask)
-		err = ahash_op_unaligned(req, op, has_state);
-	else
-		err = op(req);
-
-	return crypto_hash_errstat(crypto_hash_alg_common(tfm), err);
-}
-
 int crypto_ahash_final(struct ahash_request *req)
 {
 	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
@@ -309,7 +205,7 @@ int crypto_ahash_final(struct ahash_request *req)
 	if (IS_ENABLED(CONFIG_CRYPTO_STATS))
 		atomic64_inc(&hash_get_stat(alg)->hash_cnt);
 
-	return crypto_ahash_op(req, tfm->final, true);
+	return crypto_hash_errstat(alg, tfm->final(req));
 }
 EXPORT_SYMBOL_GPL(crypto_ahash_final);
 
@@ -325,7 +221,7 @@ int crypto_ahash_finup(struct ahash_request *req)
 		atomic64_add(req->nbytes, &istat->hash_tlen);
 	}
 
-	return crypto_ahash_op(req, tfm->finup, true);
+	return crypto_hash_errstat(alg, tfm->finup(req));
 }
 EXPORT_SYMBOL_GPL(crypto_ahash_finup);
 
@@ -333,6 +229,7 @@ int crypto_ahash_digest(struct ahash_request *req)
 {
 	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
 	struct hash_alg_common *alg = crypto_hash_alg_common(tfm);
+	int err;
 
 	if (IS_ENABLED(CONFIG_CRYPTO_STATS)) {
 		struct crypto_istat_hash *istat = hash_get_stat(alg);
@@ -342,9 +239,11 @@ int crypto_ahash_digest(struct ahash_request *req)
 	}
 
 	if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
-		return crypto_hash_errstat(alg, -ENOKEY);
+		err = -ENOKEY;
+	else
+		err = tfm->digest(req);
 
-	return crypto_ahash_op(req, tfm->digest, false);
+	return crypto_hash_errstat(alg, err);
 }
 EXPORT_SYMBOL_GPL(crypto_ahash_digest);
 
diff --git a/crypto/shash.c b/crypto/shash.c
index 409b33f9c97c..359702c2cd02 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -541,6 +541,10 @@ int hash_prepare_alg(struct hash_alg_common *alg)
 	if (alg->digestsize > HASH_MAX_DIGESTSIZE)
 		return -EINVAL;
 
+	/* alignmask is not useful for hashes, so it is not supported. */
+	if (base->cra_alignmask)
+		return -EINVAL;
+
 	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
 
 	if (IS_ENABLED(CONFIG_CRYPTO_STATS))
@@ -557,10 +561,6 @@ static int shash_prepare_alg(struct shash_alg *alg)
 	if (alg->descsize > HASH_MAX_DESCSIZE)
 		return -EINVAL;
 
-	/* alignmask is not useful for shash, so it is not supported. */
-	if (base->cra_alignmask)
-		return -EINVAL;
-
 	if ((alg->export && !alg->import) || (alg->import && !alg->export))
 		return -EINVAL;