crypto: s390 - add System z hardware support for GHASH

This patch adds System z hardware acceleration support for the GHASH
algorithm for GCM (Galois/Counter Mode).
The hardware support is available beginning with System z196.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

4 files changed, 174 insertions, 0 deletions

diff --git a/arch/s390/crypto/Makefile b/arch/s390/crypto/Makefile
index 1cf81d77c5a..7f0b7cda625 100644
--- a/arch/s390/crypto/Makefile
+++ b/arch/s390/crypto/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_CRYPTO_SHA512_S390) += sha512_s390.o sha_common.o
 obj-$(CONFIG_CRYPTO_DES_S390) += des_s390.o
 obj-$(CONFIG_CRYPTO_AES_S390) += aes_s390.o
 obj-$(CONFIG_S390_PRNG) += prng.o
+obj-$(CONFIG_CRYPTO_GHASH_S390) += ghash_s390.o
diff --git a/arch/s390/crypto/crypt_s390.h b/arch/s390/crypto/crypt_s390.h
index 7cbfaf080a5..eb2e39186b6 100644
--- a/arch/s390/crypto/crypt_s390.h
+++ b/arch/s390/crypto/crypt_s390.h
@@ -91,6 +91,7 @@ enum crypt_s390_kimd_func {
         KIMD_SHA_1   = CRYPT_S390_KIMD | 1,
         KIMD_SHA_256 = CRYPT_S390_KIMD | 2,
         KIMD_SHA_512 = CRYPT_S390_KIMD | 3,
+        KIMD_GHASH   = CRYPT_S390_KIMD | 65,
 };
 
 /*
diff --git a/arch/s390/crypto/ghash_s390.c b/arch/s390/crypto/ghash_s390.c
new file mode 100644
index 00000000000..b1bd170f24b
--- /dev/null
+++ b/arch/s390/crypto/ghash_s390.c
@@ -0,0 +1,162 @@
+/*
+ * Cryptographic API.
+ *
+ * s390 implementation of the GHASH algorithm for GCM (Galois/Counter Mode).
+ *
+ * Copyright IBM Corp. 2011
+ * Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
+ */
+
+#include <crypto/internal/hash.h>
+#include <linux/module.h>
+
+#include "crypt_s390.h"
+
+#define GHASH_BLOCK_SIZE        16
+#define GHASH_DIGEST_SIZE       16
+
+struct ghash_ctx {
+        u8 icv[16];
+        u8 key[16];
+};
+
+struct ghash_desc_ctx {
+        u8 buffer[GHASH_BLOCK_SIZE];
+        u32 bytes;
+};
+
+static int ghash_init(struct shash_desc *desc)
+{
+        struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
+
+        memset(dctx, 0, sizeof(*dctx));
+
+        return 0;
+}
+
+static int ghash_setkey(struct crypto_shash *tfm,
+                        const u8 *key, unsigned int keylen)
+{
+        struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
+
+        if (keylen != GHASH_BLOCK_SIZE) {
+                crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
+                return -EINVAL;
+        }
+
+        memcpy(ctx->key, key, GHASH_BLOCK_SIZE);
+        memset(ctx->icv, 0, GHASH_BLOCK_SIZE);
+
+        return 0;
+}
+
+static int ghash_update(struct shash_desc *desc,
+                         const u8 *src, unsigned int srclen)
+{
+        struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
+        struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
+        unsigned int n;
+        u8 *buf = dctx->buffer;
+        int ret;
+
+        if (dctx->bytes) {
+                u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
+
+                n = min(srclen, dctx->bytes);
+                dctx->bytes -= n;
+                srclen -= n;
+
+                memcpy(pos, src, n);
+                src += n;
+
+                if (!dctx->bytes) {
+                        ret = crypt_s390_kimd(KIMD_GHASH, ctx, buf,
+                                              GHASH_BLOCK_SIZE);
+                        BUG_ON(ret != GHASH_BLOCK_SIZE);
+                }
+        }
+
+        n = srclen & ~(GHASH_BLOCK_SIZE - 1);
+        if (n) {
+                ret = crypt_s390_kimd(KIMD_GHASH, ctx, src, n);
+                BUG_ON(ret != n);
+                src += n;
+                srclen -= n;
+        }
+
+        if (srclen) {
+                dctx->bytes = GHASH_BLOCK_SIZE - srclen;
+                memcpy(buf, src, srclen);
+        }
+
+        return 0;
+}
+
+static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
+{
+        u8 *buf = dctx->buffer;
+        int ret;
+
+        if (dctx->bytes) {
+                u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
+
+                memset(pos, 0, dctx->bytes);
+
+                ret = crypt_s390_kimd(KIMD_GHASH, ctx, buf, GHASH_BLOCK_SIZE);
+                BUG_ON(ret != GHASH_BLOCK_SIZE);
+        }
+
+        dctx->bytes = 0;
+}
+
+static int ghash_final(struct shash_desc *desc, u8 *dst)
+{
+        struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
+        struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
+
+        ghash_flush(ctx, dctx);
+        memcpy(dst, ctx->icv, GHASH_BLOCK_SIZE);
+
+        return 0;
+}
+
+static struct shash_alg ghash_alg = {
+        .digestsize     = GHASH_DIGEST_SIZE,
+        .init           = ghash_init,
+        .update         = ghash_update,
+        .final          = ghash_final,
+        .setkey         = ghash_setkey,
+        .descsize       = sizeof(struct ghash_desc_ctx),
+        .base           = {
+                .cra_name               = "ghash",
+                .cra_driver_name        = "ghash-s390",
+                .cra_priority           = CRYPT_S390_PRIORITY,
+                .cra_flags              = CRYPTO_ALG_TYPE_SHASH,
+                .cra_blocksize          = GHASH_BLOCK_SIZE,
+                .cra_ctxsize            = sizeof(struct ghash_ctx),
+                .cra_module             = THIS_MODULE,
+                .cra_list               = LIST_HEAD_INIT(ghash_alg.base.cra_list),
+        },
+};
+
+static int __init ghash_mod_init(void)
+{
+        if (!crypt_s390_func_available(KIMD_GHASH,
+                                       CRYPT_S390_MSA | CRYPT_S390_MSA4))
+                return -EOPNOTSUPP;
+
+        return crypto_register_shash(&ghash_alg);
+}
+
+static void __exit ghash_mod_exit(void)
+{
+        crypto_unregister_shash(&ghash_alg);
+}
+
+module_init(ghash_mod_init);
+module_exit(ghash_mod_exit);
+
+MODULE_ALIAS("ghash");
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("GHASH Message Digest Algorithm, s390 implementation");
diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig
index 78df36adbe6..d459cc7894d 100644
--- a/drivers/crypto/Kconfig
+++ b/drivers/crypto/Kconfig
@@ -151,6 +151,16 @@ config S390_PRNG
           ANSI X9.17 standard. The PRNG is usable via the char device
           /dev/prandom.
 
+config CRYPTO_GHASH_S390
+        tristate "GHASH digest algorithm"
+        depends on S390
+        select CRYPTO_HASH
+        help
+          This is the s390 hardware accelerated implementation of the
+          GHASH message digest algorithm for GCM (Galois/Counter Mode).
+
+          It is available as of z196.
+
 config CRYPTO_DEV_MV_CESA
         tristate "Marvell's Cryptographic Engine"
         depends on PLAT_ORION