arch/s390/crypto/ghash_s390.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Cryptographic API.
   4  *
   5  * s390 implementation of the GHASH algorithm for GCM (Galois/Counter Mode).
   6  *
   7  * Copyright IBM Corp. 2011
   8  * Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
   9  */
  10
  11 #include <crypto/internal/hash.h>
  12 #include <linux/module.h>
  13 #include <linux/cpufeature.h>
  14 #include <asm/cpacf.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
  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                         cpacf_kimd(CPACF_KIMD_GHASH, dctx, buf,
  75                                    GHASH_BLOCK_SIZE);
  76                 }
  77         }
  78
  79         n = srclen & ~(GHASH_BLOCK_SIZE - 1);
  80         if (n) {
  81                 cpacf_kimd(CPACF_KIMD_GHASH, dctx, src, n);
  82                 src += n;
  83                 srclen -= n;
  84         }
  85
  86         if (srclen) {
  87                 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
  88                 memcpy(buf, src, srclen);
  89         }
  90
  91         return 0;
  92 }
  93
  94 static int ghash_flush(struct ghash_desc_ctx *dctx)
  95 {
  96         u8 *buf = dctx->buffer;
  97
  98         if (dctx->bytes) {
  99                 u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
 100
 101                 memset(pos, 0, dctx->bytes);
 102                 cpacf_kimd(CPACF_KIMD_GHASH, dctx, buf, GHASH_BLOCK_SIZE);
 103                 dctx->bytes = 0;
 104         }
 105
 106         return 0;
 107 }
 108
 109 static int ghash_final(struct shash_desc *desc, u8 *dst)
 110 {
 111         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 112         int ret;
 113
 114         ret = ghash_flush(dctx);
 115         if (!ret)
 116                 memcpy(dst, dctx->icv, GHASH_BLOCK_SIZE);
 117         return ret;
 118 }
 119
 120 static struct shash_alg ghash_alg = {
 121         .digestsize     = GHASH_DIGEST_SIZE,
 122         .init           = ghash_init,
 123         .update         = ghash_update,
 124         .final          = ghash_final,
 125         .setkey         = ghash_setkey,
 126         .descsize       = sizeof(struct ghash_desc_ctx),
 127         .base           = {
 128                 .cra_name               = "ghash",
 129                 .cra_driver_name        = "ghash-s390",
 130                 .cra_priority           = 300,
 131                 .cra_flags              = CRYPTO_ALG_TYPE_SHASH,
 132                 .cra_blocksize          = GHASH_BLOCK_SIZE,
 133                 .cra_ctxsize            = sizeof(struct ghash_ctx),
 134                 .cra_module             = THIS_MODULE,
 135         },
 136 };
 137
 138 static int __init ghash_mod_init(void)
 139 {
 140         if (!cpacf_query_func(CPACF_KIMD, CPACF_KIMD_GHASH))
 141                 return -EOPNOTSUPP;
 142
 143         return crypto_register_shash(&ghash_alg);
 144 }
 145
 146 static void __exit ghash_mod_exit(void)
 147 {
 148         crypto_unregister_shash(&ghash_alg);
 149 }
 150
 151 module_cpu_feature_match(MSA, ghash_mod_init);
 152 module_exit(ghash_mod_exit);
 153
 154 MODULE_ALIAS_CRYPTO("ghash");
 155
 156 MODULE_LICENSE("GPL");
 157 MODULE_DESCRIPTION("GHASH Message Digest Algorithm, s390 implementation");