crypto: shash - remove support for nonzero alignmask

Currently, the shash API checks the alignment of all message, key, and
digest 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.  In the case of the message buffer,
cryptographic hash functions internally operate on fixed-size blocks, so
implementations end up needing to deal with byte-aligned data anyway
because the length(s) passed to ->update might not be divisible by the
block size.  Word-alignment of the message can theoretically be helpful
for CRCs, like what was being done in crc32c-sparc64.  But in practice
it's better for the algorithms to use unaligned accesses or align the
message themselves.  A similar argument applies to the key and digest.

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

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

1 files changed, 8 insertions, 120 deletions

diff --git a/crypto/shash.c b/crypto/shash.c
index 52420c41db44ae..409b33f9c97cc1 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -10,15 +10,12 @@
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/slab.h>
 #include <linux/seq_file.h>
 #include <linux/string.h>
 #include <net/netlink.h>
 
 #include "hash.h"
 
-#define MAX_SHASH_ALIGNMASK 63
-
 static const struct crypto_type crypto_shash_type;
 
 static inline struct crypto_istat_hash *shash_get_stat(struct shash_alg *alg)
@@ -38,27 +35,6 @@ int shash_no_setkey(struct crypto_shash *tfm, const u8 *key,
 }
 EXPORT_SYMBOL_GPL(shash_no_setkey);
 
-static int shash_setkey_unaligned(struct crypto_shash *tfm, const u8 *key,
-				  unsigned int keylen)
-{
-	struct shash_alg *shash = crypto_shash_alg(tfm);
-	unsigned long alignmask = crypto_shash_alignmask(tfm);
-	unsigned long absize;
-	u8 *buffer, *alignbuffer;
-	int err;
-
-	absize = keylen + (alignmask & ~(crypto_tfm_ctx_alignment() - 1));
-	buffer = kmalloc(absize, GFP_ATOMIC);
-	if (!buffer)
-		return -ENOMEM;
-
-	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
-	memcpy(alignbuffer, key, keylen);
-	err = shash->setkey(tfm, alignbuffer, keylen);
-	kfree_sensitive(buffer);
-	return err;
-}
-
 static void shash_set_needkey(struct crypto_shash *tfm, struct shash_alg *alg)
 {
 	if (crypto_shash_alg_needs_key(alg))
@@ -69,14 +45,9 @@ int crypto_shash_setkey(struct crypto_shash *tfm, const u8 *key,
 			unsigned int keylen)
 {
 	struct shash_alg *shash = crypto_shash_alg(tfm);
-	unsigned long alignmask = crypto_shash_alignmask(tfm);
 	int err;
 
-	if ((unsigned long)key & alignmask)
-		err = shash_setkey_unaligned(tfm, key, keylen);
-	else
-		err = shash->setkey(tfm, key, keylen);
-
+	err = shash->setkey(tfm, key, keylen);
 	if (unlikely(err)) {
 		shash_set_needkey(tfm, shash);
 		return err;
@@ -87,110 +58,35 @@ int crypto_shash_setkey(struct crypto_shash *tfm, const u8 *key,
 }
 EXPORT_SYMBOL_GPL(crypto_shash_setkey);
 
-static int shash_update_unaligned(struct shash_desc *desc, const u8 *data,
-				  unsigned int len)
-{
-	struct crypto_shash *tfm = desc->tfm;
-	struct shash_alg *shash = crypto_shash_alg(tfm);
-	unsigned long alignmask = crypto_shash_alignmask(tfm);
-	unsigned int unaligned_len = alignmask + 1 -
-				     ((unsigned long)data & alignmask);
-	/*
-	 * We cannot count on __aligned() working for large values:
-	 * https://patchwork.kernel.org/patch/9507697/
-	 */
-	u8 ubuf[MAX_SHASH_ALIGNMASK * 2];
-	u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1);
-	int err;
-
-	if (WARN_ON(buf + unaligned_len > ubuf + sizeof(ubuf)))
-		return -EINVAL;
-
-	if (unaligned_len > len)
-		unaligned_len = len;
-
-	memcpy(buf, data, unaligned_len);
-	err = shash->update(desc, buf, unaligned_len);
-	memset(buf, 0, unaligned_len);
-
-	return err ?:
-	       shash->update(desc, data + unaligned_len, len - unaligned_len);
-}
-
 int crypto_shash_update(struct shash_desc *desc, const u8 *data,
 			unsigned int len)
 {
-	struct crypto_shash *tfm = desc->tfm;
-	struct shash_alg *shash = crypto_shash_alg(tfm);
-	unsigned long alignmask = crypto_shash_alignmask(tfm);
+	struct shash_alg *shash = crypto_shash_alg(desc->tfm);
 	int err;
 
 	if (IS_ENABLED(CONFIG_CRYPTO_STATS))
 		atomic64_add(len, &shash_get_stat(shash)->hash_tlen);
 
-	if ((unsigned long)data & alignmask)
-		err = shash_update_unaligned(desc, data, len);
-	else
-		err = shash->update(desc, data, len);
+	err = shash->update(desc, data, len);
 
 	return crypto_shash_errstat(shash, err);
 }
 EXPORT_SYMBOL_GPL(crypto_shash_update);
 
-static int shash_final_unaligned(struct shash_desc *desc, u8 *out)
-{
-	struct crypto_shash *tfm = desc->tfm;
-	unsigned long alignmask = crypto_shash_alignmask(tfm);
-	struct shash_alg *shash = crypto_shash_alg(tfm);
-	unsigned int ds = crypto_shash_digestsize(tfm);
-	/*
-	 * We cannot count on __aligned() working for large values:
-	 * https://patchwork.kernel.org/patch/9507697/
-	 */
-	u8 ubuf[MAX_SHASH_ALIGNMASK + HASH_MAX_DIGESTSIZE];
-	u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1);
-	int err;
-
-	if (WARN_ON(buf + ds > ubuf + sizeof(ubuf)))
-		return -EINVAL;
-
-	err = shash->final(desc, buf);
-	if (err)
-		goto out;
-
-	memcpy(out, buf, ds);
-
-out:
-	memset(buf, 0, ds);
-	return err;
-}
-
 int crypto_shash_final(struct shash_desc *desc, u8 *out)
 {
-	struct crypto_shash *tfm = desc->tfm;
-	struct shash_alg *shash = crypto_shash_alg(tfm);
-	unsigned long alignmask = crypto_shash_alignmask(tfm);
+	struct shash_alg *shash = crypto_shash_alg(desc->tfm);
 	int err;
 
 	if (IS_ENABLED(CONFIG_CRYPTO_STATS))
 		atomic64_inc(&shash_get_stat(shash)->hash_cnt);
 
-	if ((unsigned long)out & alignmask)
-		err = shash_final_unaligned(desc, out);
-	else
-		err = shash->final(desc, out);
+	err = shash->final(desc, out);
 
 	return crypto_shash_errstat(shash, err);
 }
 EXPORT_SYMBOL_GPL(crypto_shash_final);
 
-static int shash_finup_unaligned(struct shash_desc *desc, const u8 *data,
-				 unsigned int len, u8 *out)
-{
-	return shash_update_unaligned(desc, data, len) ?:
-	       shash_final_unaligned(desc, out);
-}
-
 static int shash_default_finup(struct shash_desc *desc, const u8 *data,
 			       unsigned int len, u8 *out)
 {
@@ -205,7 +101,6 @@ int crypto_shash_finup(struct shash_desc *desc, const u8 *data,
 {
 	struct crypto_shash *tfm = desc->tfm;
 	struct shash_alg *shash = crypto_shash_alg(tfm);
-	unsigned long alignmask = crypto_shash_alignmask(tfm);
 	int err;
 
 	if (IS_ENABLED(CONFIG_CRYPTO_STATS)) {
@@ -215,11 +110,7 @@ int crypto_shash_finup(struct shash_desc *desc, const u8 *data,
 		atomic64_add(len, &istat->hash_tlen);
 	}
 
-	if (((unsigned long)data | (unsigned long)out) & alignmask)
-		err = shash_finup_unaligned(desc, data, len, out);
-	else
-		err = shash->finup(desc, data, len, out);
-
+	err = shash->finup(desc, data, len, out);
 
 	return crypto_shash_errstat(shash, err);
 }
@@ -239,7 +130,6 @@ int crypto_shash_digest(struct shash_desc *desc, const u8 *data,
 {
 	struct crypto_shash *tfm = desc->tfm;
 	struct shash_alg *shash = crypto_shash_alg(tfm);
-	unsigned long alignmask = crypto_shash_alignmask(tfm);
 	int err;
 
 	if (IS_ENABLED(CONFIG_CRYPTO_STATS)) {
@@ -251,9 +141,6 @@ int crypto_shash_digest(struct shash_desc *desc, const u8 *data,
 
 	if (crypto_shash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
 		err = -ENOKEY;
-	else if (((unsigned long)data | (unsigned long)out) & alignmask)
-		err = shash->init(desc) ?:
-		      shash_finup_unaligned(desc, data, len, out);
 	else
 		err = shash->digest(desc, data, len, out);
 
@@ -670,7 +557,8 @@ static int shash_prepare_alg(struct shash_alg *alg)
 	if (alg->descsize > HASH_MAX_DESCSIZE)
 		return -EINVAL;
 
-	if (base->cra_alignmask > MAX_SHASH_ALIGNMASK)
+	/* 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))