arch/s390/crypto/chacha-glue.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * s390 ChaCha stream cipher.
   4  *
   5  * Copyright IBM Corp. 2021
   6  */
   7
   8 #define KMSG_COMPONENT "chacha_s390"
   9 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  10
  11 #include <crypto/internal/chacha.h>
  12 #include <crypto/internal/skcipher.h>
  13 #include <crypto/algapi.h>
  14 #include <linux/cpufeature.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/sizes.h>
  18 #include <asm/fpu.h>
  19 #include "chacha-s390.h"
  20
  21 static void chacha20_crypt_s390(u32 *state, u8 *dst, const u8 *src,
  22                                 unsigned int nbytes, const u32 *key,
  23                                 u32 *counter)
  24 {
  25         DECLARE_KERNEL_FPU_ONSTACK32(vxstate);
  26
  27         kernel_fpu_begin(&vxstate, KERNEL_VXR);
  28         chacha20_vx(dst, src, nbytes, key, counter);
  29         kernel_fpu_end(&vxstate, KERNEL_VXR);
  30
  31         *counter += round_up(nbytes, CHACHA_BLOCK_SIZE) / CHACHA_BLOCK_SIZE;
  32 }
  33
  34 static int chacha20_s390(struct skcipher_request *req)
  35 {
  36         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  37         struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
  38         u32 state[CHACHA_STATE_WORDS] __aligned(16);
  39         struct skcipher_walk walk;
  40         unsigned int nbytes;
  41         int rc;
  42
  43         rc = skcipher_walk_virt(&walk, req, false);
  44         chacha_init_generic(state, ctx->key, req->iv);
  45
  46         while (walk.nbytes > 0) {
  47                 nbytes = walk.nbytes;
  48                 if (nbytes < walk.total)
  49                         nbytes = round_down(nbytes, walk.stride);
  50
  51                 if (nbytes <= CHACHA_BLOCK_SIZE) {
  52                         chacha_crypt_generic(state, walk.dst.virt.addr,
  53                                              walk.src.virt.addr, nbytes,
  54                                              ctx->nrounds);
  55                 } else {
  56                         chacha20_crypt_s390(state, walk.dst.virt.addr,
  57                                             walk.src.virt.addr, nbytes,
  58                                             &state[4], &state[12]);
  59                 }
  60                 rc = skcipher_walk_done(&walk, walk.nbytes - nbytes);
  61         }
  62         return rc;
  63 }
  64
  65 void hchacha_block_arch(const u32 *state, u32 *stream, int nrounds)
  66 {
  67         /* TODO: implement hchacha_block_arch() in assembly */
  68         hchacha_block_generic(state, stream, nrounds);
  69 }
  70 EXPORT_SYMBOL(hchacha_block_arch);
  71
  72 void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv)
  73 {
  74         chacha_init_generic(state, key, iv);
  75 }
  76 EXPORT_SYMBOL(chacha_init_arch);
  77
  78 void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
  79                        unsigned int bytes, int nrounds)
  80 {
  81         /* s390 chacha20 implementation has 20 rounds hard-coded,
  82          * it cannot handle a block of data or less, but otherwise
  83          * it can handle data of arbitrary size
  84          */
  85         if (bytes <= CHACHA_BLOCK_SIZE || nrounds != 20 || !cpu_has_vx())
  86                 chacha_crypt_generic(state, dst, src, bytes, nrounds);
  87         else
  88                 chacha20_crypt_s390(state, dst, src, bytes,
  89                                     &state[4], &state[12]);
  90 }
  91 EXPORT_SYMBOL(chacha_crypt_arch);
  92
  93 static struct skcipher_alg chacha_algs[] = {
  94         {
  95                 .base.cra_name          = "chacha20",
  96                 .base.cra_driver_name   = "chacha20-s390",
  97                 .base.cra_priority      = 900,
  98                 .base.cra_blocksize     = 1,
  99                 .base.cra_ctxsize       = sizeof(struct chacha_ctx),
 100                 .base.cra_module        = THIS_MODULE,
 101
 102                 .min_keysize            = CHACHA_KEY_SIZE,
 103                 .max_keysize            = CHACHA_KEY_SIZE,
 104                 .ivsize                 = CHACHA_IV_SIZE,
 105                 .chunksize              = CHACHA_BLOCK_SIZE,
 106                 .setkey                 = chacha20_setkey,
 107                 .encrypt                = chacha20_s390,
 108                 .decrypt                = chacha20_s390,
 109         }
 110 };
 111
 112 static int __init chacha_mod_init(void)
 113 {
 114         return IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER) ?
 115                 crypto_register_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs)) : 0;
 116 }
 117
 118 static void __exit chacha_mod_fini(void)
 119 {
 120         if (IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER))
 121                 crypto_unregister_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs));
 122 }
 123
 124 module_cpu_feature_match(S390_CPU_FEATURE_VXRS, chacha_mod_init);
 125 module_exit(chacha_mod_fini);
 126
 127 MODULE_DESCRIPTION("ChaCha20 stream cipher");
 128 MODULE_LICENSE("GPL v2");
 129
 130 MODULE_ALIAS_CRYPTO("chacha20");