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 #include <linux/cpufeature.h>
  13 #include <asm/cpacf.h>
  14
  15 #define GHASH_BLOCK_SIZE        16
  16 #define GHASH_DIGEST_SIZE       16
  17
  18 struct ghash_ctx {
  19         u8 key[GHASH_BLOCK_SIZE];
  20 };
  21
  22 struct ghash_desc_ctx {
  23         u8 icv[GHASH_BLOCK_SIZE];
  24         u8 key[GHASH_BLOCK_SIZE];
  25         u8 buffer[GHASH_BLOCK_SIZE];
  26         u32 bytes;
  27 };
  28
  29 static int ghash_init(struct shash_desc *desc)
  30 {
  31         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
  32         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
  33
  34         memset(dctx, 0, sizeof(*dctx));
  35         memcpy(dctx->key, ctx->key, GHASH_BLOCK_SIZE);
  36
  37         return 0;
  38 }
  39
  40 static int ghash_setkey(struct crypto_shash *tfm,
  41                         const u8 *key, unsigned int keylen)
  42 {
  43         struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
  44
  45         if (keylen != GHASH_BLOCK_SIZE) {
  46                 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
  47                 return -EINVAL;
  48         }
  49
  50         memcpy(ctx->key, key, GHASH_BLOCK_SIZE);
  51
  52         return 0;
  53 }
  54
  55 static int ghash_update(struct shash_desc *desc,
  56                          const u8 *src, unsigned int srclen)
  57 {
  58         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
  59         unsigned int n;
  60         u8 *buf = dctx->buffer;
  61         int ret;
  62
  63         if (dctx->bytes) {
  64                 u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
  65
  66                 n = min(srclen, dctx->bytes);
  67                 dctx->bytes -= n;
  68                 srclen -= n;
  69
  70                 memcpy(pos, src, n);
  71                 src += n;
  72
  73                 if (!dctx->bytes) {
  74                         ret = cpacf_kimd(CPACF_KIMD_GHASH, dctx, buf,
  75                                          GHASH_BLOCK_SIZE);
  76                         if (ret != GHASH_BLOCK_SIZE)
  77                                 return -EIO;
  78                 }
  79         }
  80
  81         n = srclen & ~(GHASH_BLOCK_SIZE - 1);
  82         if (n) {
  83                 ret = cpacf_kimd(CPACF_KIMD_GHASH, dctx, src, n);
  84                 if (ret != n)
  85                         return -EIO;
  86                 src += n;
  87                 srclen -= n;
  88         }
  89
  90         if (srclen) {
  91                 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
  92                 memcpy(buf, src, srclen);
  93         }
  94
  95         return 0;
  96 }
  97
  98 static int ghash_flush(struct ghash_desc_ctx *dctx)
  99 {
 100         u8 *buf = dctx->buffer;
 101         int ret;
 102
 103         if (dctx->bytes) {
 104                 u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
 105
 106                 memset(pos, 0, dctx->bytes);
 107
 108                 ret = cpacf_kimd(CPACF_KIMD_GHASH, dctx, buf, GHASH_BLOCK_SIZE);
 109                 if (ret != GHASH_BLOCK_SIZE)
 110                         return -EIO;
 111
 112                 dctx->bytes = 0;
 113         }
 114
 115         return 0;
 116 }
 117
 118 static int ghash_final(struct shash_desc *desc, u8 *dst)
 119 {
 120         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 121         int ret;
 122
 123         ret = ghash_flush(dctx);
 124         if (!ret)
 125                 memcpy(dst, dctx->icv, GHASH_BLOCK_SIZE);
 126         return ret;
 127 }
 128
 129 static struct shash_alg ghash_alg = {
 130         .digestsize     = GHASH_DIGEST_SIZE,
 131         .init           = ghash_init,
 132         .update         = ghash_update,
 133         .final          = ghash_final,
 134         .setkey         = ghash_setkey,
 135         .descsize       = sizeof(struct ghash_desc_ctx),
 136         .base           = {
 137                 .cra_name               = "ghash",
 138                 .cra_driver_name        = "ghash-s390",
 139                 .cra_priority           = 300,
 140                 .cra_flags              = CRYPTO_ALG_TYPE_SHASH,
 141                 .cra_blocksize          = GHASH_BLOCK_SIZE,
 142                 .cra_ctxsize            = sizeof(struct ghash_ctx),
 143                 .cra_module             = THIS_MODULE,
 144         },
 145 };
 146
 147 static int __init ghash_mod_init(void)
 148 {
 149         if (!cpacf_query(CPACF_KIMD, CPACF_KIMD_GHASH))
 150                 return -EOPNOTSUPP;
 151
 152         return crypto_register_shash(&ghash_alg);
 153 }
 154
 155 static void __exit ghash_mod_exit(void)
 156 {
 157         crypto_unregister_shash(&ghash_alg);
 158 }
 159
 160 module_cpu_feature_match(MSA, ghash_mod_init);
 161 module_exit(ghash_mod_exit);
 162
 163 MODULE_ALIAS_CRYPTO("ghash");
 164
 165 MODULE_LICENSE("GPL");
 166 MODULE_DESCRIPTION("GHASH Message Digest Algorithm, s390 implementation");