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
  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                         cpacf_kimd(CPACF_KIMD_GHASH, dctx, buf,
  74                                    GHASH_BLOCK_SIZE);
  75                 }
  76         }
  77
  78         n = srclen & ~(GHASH_BLOCK_SIZE - 1);
  79         if (n) {
  80                 cpacf_kimd(CPACF_KIMD_GHASH, dctx, src, n);
  81                 src += n;
  82                 srclen -= n;
  83         }
  84
  85         if (srclen) {
  86                 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
  87                 memcpy(buf, src, srclen);
  88         }
  89
  90         return 0;
  91 }
  92
  93 static int ghash_flush(struct ghash_desc_ctx *dctx)
  94 {
  95         u8 *buf = dctx->buffer;
  96
  97         if (dctx->bytes) {
  98                 u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
  99
 100                 memset(pos, 0, dctx->bytes);
 101                 cpacf_kimd(CPACF_KIMD_GHASH, dctx, buf, GHASH_BLOCK_SIZE);
 102                 dctx->bytes = 0;
 103         }
 104
 105         return 0;
 106 }
 107
 108 static int ghash_final(struct shash_desc *desc, u8 *dst)
 109 {
 110         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 111         int ret;
 112
 113         ret = ghash_flush(dctx);
 114         if (!ret)
 115                 memcpy(dst, dctx->icv, GHASH_BLOCK_SIZE);
 116         return ret;
 117 }
 118
 119 static struct shash_alg ghash_alg = {
 120         .digestsize     = GHASH_DIGEST_SIZE,
 121         .init           = ghash_init,
 122         .update         = ghash_update,
 123         .final          = ghash_final,
 124         .setkey         = ghash_setkey,
 125         .descsize       = sizeof(struct ghash_desc_ctx),
 126         .base           = {
 127                 .cra_name               = "ghash",
 128                 .cra_driver_name        = "ghash-s390",
 129                 .cra_priority           = 300,
 130                 .cra_flags              = CRYPTO_ALG_TYPE_SHASH,
 131                 .cra_blocksize          = GHASH_BLOCK_SIZE,
 132                 .cra_ctxsize            = sizeof(struct ghash_ctx),
 133                 .cra_module             = THIS_MODULE,
 134         },
 135 };
 136
 137 static int __init ghash_mod_init(void)
 138 {
 139         if (!cpacf_query_func(CPACF_KIMD, CPACF_KIMD_GHASH))
 140                 return -EOPNOTSUPP;
 141
 142         return crypto_register_shash(&ghash_alg);
 143 }
 144
 145 static void __exit ghash_mod_exit(void)
 146 {
 147         crypto_unregister_shash(&ghash_alg);
 148 }
 149
 150 module_cpu_feature_match(MSA, ghash_mod_init);
 151 module_exit(ghash_mod_exit);
 152
 153 MODULE_ALIAS_CRYPTO("ghash");
 154
 155 MODULE_LICENSE("GPL");
 156 MODULE_DESCRIPTION("GHASH Message Digest Algorithm, s390 implementation");