GHASH is used by the GCM mode, which is often used in contexts where
only synchronous ciphers are permitted. So provide a synchronous version
of GHASH based on the existing code. This requires a non-SIMD fallback
to deal with invocations occurring from a context where SIMD instructions
may not be used.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
arch/arm/crypto/ghash-ce-glue.c | 78 +++++++++++++-------
1 file changed, 52 insertions(+), 26 deletions(-)
diff --git a/arch/arm/crypto/ghash-ce-glue.c b/arch/arm/crypto/ghash-ce-glue.c
index 39d1ccec1aab..ebb237ca874b 100644
--- a/arch/arm/crypto/ghash-ce-glue.c
+++ b/arch/arm/crypto/ghash-ce-glue.c
@@ -12,6 +12,7 @@
#include <asm/neon.h>
#include <asm/simd.h>
#include <asm/unaligned.h>
+#include <crypto/b128ops.h>
#include <crypto/cryptd.h>
#include <crypto/internal/hash.h>
#include <crypto/internal/simd.h>
@@ -33,6 +34,8 @@ struct ghash_key {
u64 h2[2];
u64 h3[2];
u64 h4[2];
+
+ be128 k;
};
struct ghash_desc_ctx {
@@ -65,6 +68,36 @@ static int ghash_init(struct shash_desc *desc)
return 0;
}
+static void ghash_do_update(int blocks, u64 dg[], const char *src,
+ struct ghash_key *key, const char *head)
+{
+ if (likely(crypto_simd_usable())) {
+ kernel_neon_begin();
+ pmull_ghash_update(blocks, dg, src, key, head);
+ kernel_neon_end();
+ } else {
+ be128 dst = { cpu_to_be64(dg[1]), cpu_to_be64(dg[0]) };
+
+ do {
+ const u8 *in = src;
+
+ if (head) {
+ in = head;
+ blocks++;
+ head = NULL;
+ } else {
+ src += GHASH_BLOCK_SIZE;
+ }
+
+ crypto_xor((u8 *)&dst, in, GHASH_BLOCK_SIZE);
+ gf128mul_lle(&dst, &key->k);
+ } while (--blocks);
+
+ dg[0] = be64_to_cpu(dst.b);
+ dg[1] = be64_to_cpu(dst.a);
+ }
+}
+
static int ghash_update(struct shash_desc *desc, const u8 *src,
unsigned int len)
{
@@ -88,10 +121,8 @@ static int ghash_update(struct shash_desc *desc, const u8 *src,
blocks = len / GHASH_BLOCK_SIZE;
len %= GHASH_BLOCK_SIZE;
- kernel_neon_begin();
- pmull_ghash_update(blocks, ctx->digest, src, key,
- partial ? ctx->buf : NULL);
- kernel_neon_end();
+ ghash_do_update(blocks, ctx->digest, src, key,
+ partial ? ctx->buf : NULL);
src += blocks * GHASH_BLOCK_SIZE;
partial = 0;
}
@@ -109,9 +140,7 @@ static int ghash_final(struct shash_desc *desc, u8 *dst)
struct ghash_key *key = crypto_shash_ctx(desc->tfm);
memset(ctx->buf + partial, 0, GHASH_BLOCK_SIZE - partial);
- kernel_neon_begin();
- pmull_ghash_update(1, ctx->digest, ctx->buf, key, NULL);
- kernel_neon_end();
+ ghash_do_update(1, ctx->digest, ctx->buf, key, NULL);
}
put_unaligned_be64(ctx->digest[1], dst);
put_unaligned_be64(ctx->digest[0], dst + 8);
@@ -135,24 +164,25 @@ static int ghash_setkey(struct crypto_shash *tfm,
const u8 *inkey, unsigned int keylen)
{
struct ghash_key *key = crypto_shash_ctx(tfm);
- be128 h, k;
+ be128 h;
if (keylen != GHASH_BLOCK_SIZE) {
crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
return -EINVAL;
}
- memcpy(&k, inkey, GHASH_BLOCK_SIZE);
- ghash_reflect(key->h, &k);
+ /* needed for the fallback */
+ memcpy(&key->k, inkey, GHASH_BLOCK_SIZE);
+ ghash_reflect(key->h, &key->k);
- h = k;
- gf128mul_lle(&h, &k);
+ h = key->k;
+ gf128mul_lle(&h, &key->k);
ghash_reflect(key->h2, &h);
- gf128mul_lle(&h, &k);
+ gf128mul_lle(&h, &key->k);
ghash_reflect(key->h3, &h);
- gf128mul_lle(&h, &k);
+ gf128mul_lle(&h, &key->k);
ghash_reflect(key->h4, &h);
return 0;
@@ -165,15 +195,13 @@ static struct shash_alg ghash_alg = {
.final = ghash_final,
.setkey = ghash_setkey,
.descsize = sizeof(struct ghash_desc_ctx),
- .base = {
- .cra_name = "__ghash",
- .cra_driver_name = "__driver-ghash-ce",
- .cra_priority = 0,
- .cra_flags = CRYPTO_ALG_INTERNAL,
- .cra_blocksize = GHASH_BLOCK_SIZE,
- .cra_ctxsize = sizeof(struct ghash_key),
- .cra_module = THIS_MODULE,
- },
+
+ .base.cra_name = "ghash",
+ .base.cra_driver_name = "ghash-ce-sync",
+ .base.cra_priority = 300 - 1,
+ .base.cra_blocksize = GHASH_BLOCK_SIZE,
+ .base.cra_ctxsize = sizeof(struct ghash_key),
+ .base.cra_module = THIS_MODULE,
};
static int ghash_async_init(struct ahash_request *req)
@@ -288,9 +316,7 @@ static int ghash_async_init_tfm(struct crypto_tfm *tfm)
struct cryptd_ahash *cryptd_tfm;
struct ghash_async_ctx *ctx = crypto_tfm_ctx(tfm);
- cryptd_tfm = cryptd_alloc_ahash("__driver-ghash-ce",
- CRYPTO_ALG_INTERNAL,
- CRYPTO_ALG_INTERNAL);
+ cryptd_tfm = cryptd_alloc_ahash("ghash-ce-sync", 0, 0);
if (IS_ERR(cryptd_tfm))
return PTR_ERR(cryptd_tfm);
ctx->cryptd_tfm = cryptd_tfm;
--
2.20.1
