arch/s390/crypto/ghash_s390.c

   1 /*
   2  * Cryptographic API.
   3  *
   4  * s390 implementation of the GHASH algorithm for GCM (Galois/Counter Mode).
   5  *
   6  * Copyright IBM Corp. 2011
   7  * Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
   8  */
   9
  10 #include <crypto/internal/hash.h>
  11 #include <linux/module.h>
  12
  13 #include "crypt_s390.h"
  14
  15 #define GHASH_BLOCK_SIZE        16
  16 #define GHASH_DIGEST_SIZE       16
  17
  18 struct ghash_ctx {
  19         u8 icv[16];
  20         u8 key[16];
  21 };
  22
  23 struct ghash_desc_ctx {
  24         u8 buffer[GHASH_BLOCK_SIZE];
  25         u32 bytes;
  26 };
  27
  28 static int ghash_init(struct shash_desc *desc)
  29 {
  30         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
  31
  32         memset(dctx, 0, sizeof(*dctx));
  33
  34         return 0;
  35 }
  36
  37 static int ghash_setkey(struct crypto_shash *tfm,
  38                         const u8 *key, unsigned int keylen)
  39 {
  40         struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
  41
  42         if (keylen != GHASH_BLOCK_SIZE) {
  43                 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
  44                 return -EINVAL;
  45         }
  46
  47         memcpy(ctx->key, key, GHASH_BLOCK_SIZE);
  48         memset(ctx->icv, 0, GHASH_BLOCK_SIZE);
  49
  50         return 0;
  51 }
  52
  53 static int ghash_update(struct shash_desc *desc,
  54                          const u8 *src, unsigned int srclen)
  55 {
  56         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
  57         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
  58         unsigned int n;
  59         u8 *buf = dctx->buffer;
  60         int ret;
  61
  62         if (dctx->bytes) {
  63                 u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
  64
  65                 n = min(srclen, dctx->bytes);
  66                 dctx->bytes -= n;
  67                 srclen -= n;
  68
  69                 memcpy(pos, src, n);
  70                 src += n;
  71
  72                 if (!dctx->bytes) {
  73                         ret = crypt_s390_kimd(KIMD_GHASH, ctx, buf,
  74                                               GHASH_BLOCK_SIZE);
  75                         BUG_ON(ret != GHASH_BLOCK_SIZE);
  76                 }
  77         }
  78
  79         n = srclen & ~(GHASH_BLOCK_SIZE - 1);
  80         if (n) {
  81                 ret = crypt_s390_kimd(KIMD_GHASH, ctx, src, n);
  82                 BUG_ON(ret != n);
  83                 src += n;
  84                 srclen -= n;
  85         }
  86
  87         if (srclen) {
  88                 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
  89                 memcpy(buf, src, srclen);
  90         }
  91
  92         return 0;
  93 }
  94
  95 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
  96 {
  97         u8 *buf = dctx->buffer;
  98         int ret;
  99
 100         if (dctx->bytes) {
 101                 u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
 102
 103                 memset(pos, 0, dctx->bytes);
 104
 105                 ret = crypt_s390_kimd(KIMD_GHASH, ctx, buf, GHASH_BLOCK_SIZE);
 106                 BUG_ON(ret != GHASH_BLOCK_SIZE);
 107         }
 108
 109         dctx->bytes = 0;
 110 }
 111
 112 static int ghash_final(struct shash_desc *desc, u8 *dst)
 113 {
 114         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 115         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
 116
 117         ghash_flush(ctx, dctx);
 118         memcpy(dst, ctx->icv, GHASH_BLOCK_SIZE);
 119
 120         return 0;
 121 }
 122
 123 static struct shash_alg ghash_alg = {
 124         .digestsize     = GHASH_DIGEST_SIZE,
 125         .init           = ghash_init,
 126         .update         = ghash_update,
 127         .final          = ghash_final,
 128         .setkey         = ghash_setkey,
 129         .descsize       = sizeof(struct ghash_desc_ctx),
 130         .base           = {
 131                 .cra_name               = "ghash",
 132                 .cra_driver_name        = "ghash-s390",
 133                 .cra_priority           = CRYPT_S390_PRIORITY,
 134                 .cra_flags              = CRYPTO_ALG_TYPE_SHASH,
 135                 .cra_blocksize          = GHASH_BLOCK_SIZE,
 136                 .cra_ctxsize            = sizeof(struct ghash_ctx),
 137                 .cra_module             = THIS_MODULE,
 138         },
 139 };
 140
 141 static int __init ghash_mod_init(void)
 142 {
 143         if (!crypt_s390_func_available(KIMD_GHASH,
 144                                        CRYPT_S390_MSA | CRYPT_S390_MSA4))
 145                 return -EOPNOTSUPP;
 146
 147         return crypto_register_shash(&ghash_alg);
 148 }
 149
 150 static void __exit ghash_mod_exit(void)
 151 {
 152         crypto_unregister_shash(&ghash_alg);
 153 }
 154
 155 module_init(ghash_mod_init);
 156 module_exit(ghash_mod_exit);
 157
 158 MODULE_ALIAS("ghash");
 159
 160 MODULE_LICENSE("GPL");
 161 MODULE_DESCRIPTION("GHASH Message Digest Algorithm, s390 implementation");