kernel/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
  14 #include "crypt_s390.h"
  15
  16 #define GHASH_BLOCK_SIZE        16
  17 #define GHASH_DIGEST_SIZE       16
  18
  19 struct ghash_ctx {
  20         u8 key[GHASH_BLOCK_SIZE];
  21 };
  22
  23 struct ghash_desc_ctx {
  24         u8 icv[GHASH_BLOCK_SIZE];
  25         u8 key[GHASH_BLOCK_SIZE];
  26         u8 buffer[GHASH_BLOCK_SIZE];
  27         u32 bytes;
  28 };
  29
  30 static int ghash_init(struct shash_desc *desc)
  31 {
  32         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
  33         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
  34
  35         memset(dctx, 0, sizeof(*dctx));
  36         memcpy(dctx->key, ctx->key, GHASH_BLOCK_SIZE);
  37
  38         return 0;
  39 }
  40
  41 static int ghash_setkey(struct crypto_shash *tfm,
  42                         const u8 *key, unsigned int keylen)
  43 {
  44         struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
  45
  46         if (keylen != GHASH_BLOCK_SIZE) {
  47                 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
  48                 return -EINVAL;
  49         }
  50
  51         memcpy(ctx->key, key, GHASH_BLOCK_SIZE);
  52
  53         return 0;
  54 }
  55
  56 static int ghash_update(struct shash_desc *desc,
  57                          const u8 *src, unsigned int srclen)
  58 {
  59         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
  60         unsigned int n;
  61         u8 *buf = dctx->buffer;
  62         int ret;
  63
  64         if (dctx->bytes) {
  65                 u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
  66
  67                 n = min(srclen, dctx->bytes);
  68                 dctx->bytes -= n;
  69                 srclen -= n;
  70
  71                 memcpy(pos, src, n);
  72                 src += n;
  73
  74                 if (!dctx->bytes) {
  75                         ret = crypt_s390_kimd(KIMD_GHASH, dctx, buf,
  76                                               GHASH_BLOCK_SIZE);
  77                         if (ret != GHASH_BLOCK_SIZE)
  78                                 return -EIO;
  79                 }
  80         }
  81
  82         n = srclen & ~(GHASH_BLOCK_SIZE - 1);
  83         if (n) {
  84                 ret = crypt_s390_kimd(KIMD_GHASH, dctx, src, n);
  85                 if (ret != n)
  86                         return -EIO;
  87                 src += n;
  88                 srclen -= n;
  89         }
  90
  91         if (srclen) {
  92                 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
  93                 memcpy(buf, src, srclen);
  94         }
  95
  96         return 0;
  97 }
  98
  99 static int ghash_flush(struct ghash_desc_ctx *dctx)
 100 {
 101         u8 *buf = dctx->buffer;
 102         int ret;
 103
 104         if (dctx->bytes) {
 105                 u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
 106
 107                 memset(pos, 0, dctx->bytes);
 108
 109                 ret = crypt_s390_kimd(KIMD_GHASH, dctx, buf, GHASH_BLOCK_SIZE);
 110                 if (ret != GHASH_BLOCK_SIZE)
 111                         return -EIO;
 112
 113                 dctx->bytes = 0;
 114         }
 115
 116         return 0;
 117 }
 118
 119 static int ghash_final(struct shash_desc *desc, u8 *dst)
 120 {
 121         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 122         int ret;
 123
 124         ret = ghash_flush(dctx);
 125         if (!ret)
 126                 memcpy(dst, dctx->icv, GHASH_BLOCK_SIZE);
 127         return ret;
 128 }
 129
 130 static struct shash_alg ghash_alg = {
 131         .digestsize     = GHASH_DIGEST_SIZE,
 132         .init           = ghash_init,
 133         .update         = ghash_update,
 134         .final          = ghash_final,
 135         .setkey         = ghash_setkey,
 136         .descsize       = sizeof(struct ghash_desc_ctx),
 137         .base           = {
 138                 .cra_name               = "ghash",
 139                 .cra_driver_name        = "ghash-s390",
 140                 .cra_priority           = CRYPT_S390_PRIORITY,
 141                 .cra_flags              = CRYPTO_ALG_TYPE_SHASH,
 142                 .cra_blocksize          = GHASH_BLOCK_SIZE,
 143                 .cra_ctxsize            = sizeof(struct ghash_ctx),
 144                 .cra_module             = THIS_MODULE,
 145         },
 146 };
 147
 148 static int __init ghash_mod_init(void)
 149 {
 150         if (!crypt_s390_func_available(KIMD_GHASH,
 151                                        CRYPT_S390_MSA | CRYPT_S390_MSA4))
 152                 return -EOPNOTSUPP;
 153
 154         return crypto_register_shash(&ghash_alg);
 155 }
 156
 157 static void __exit ghash_mod_exit(void)
 158 {
 159         crypto_unregister_shash(&ghash_alg);
 160 }
 161
 162 module_cpu_feature_match(MSA, ghash_mod_init);
 163 module_exit(ghash_mod_exit);
 164
 165 MODULE_ALIAS_CRYPTO("ghash");
 166
 167 MODULE_LICENSE("GPL");
 168 MODULE_DESCRIPTION("GHASH Message Digest Algorithm, s390 implementation");