target/linux/generic/backport-5.4/080-wireguard-0027-crypto-curve25519-implement-generic-KPP-driver.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Ard Biesheuvel <ardb@kernel.org>
   3 Date: Fri, 8 Nov 2019 13:22:34 +0100
   4 Subject: [PATCH] crypto: curve25519 - implement generic KPP driver
   5
   6 commit ee772cb641135739c1530647391d5a04c39db192 upstream.
   7
   8 Expose the generic Curve25519 library via the crypto API KPP interface.
   9
  10 Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
  11 Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
  12 Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
  13 ---
  14  crypto/Kconfig              |  5 +++
  15  crypto/Makefile             |  1 +
  16  crypto/curve25519-generic.c | 90 +++++++++++++++++++++++++++++++++++++
  17  3 files changed, 96 insertions(+)
  18  create mode 100644 crypto/curve25519-generic.c
  19
  20 --- a/crypto/Kconfig
  21 +++ b/crypto/Kconfig
  22 @@ -264,6 +264,11 @@ config CRYPTO_ECRDSA
  23           standard algorithms (called GOST algorithms). Only signature verification
  24           is implemented.
  25
  26 +config CRYPTO_CURVE25519
  27 +       tristate "Curve25519 algorithm"
  28 +       select CRYPTO_KPP
  29 +       select CRYPTO_LIB_CURVE25519_GENERIC
  30 +
  31  comment "Authenticated Encryption with Associated Data"
  32
  33  config CRYPTO_CCM
  34 --- a/crypto/Makefile
  35 +++ b/crypto/Makefile
  36 @@ -167,6 +167,7 @@ obj-$(CONFIG_CRYPTO_ZSTD) += zstd.o
  37  obj-$(CONFIG_CRYPTO_OFB) += ofb.o
  38  obj-$(CONFIG_CRYPTO_ECC) += ecc.o
  39  obj-$(CONFIG_CRYPTO_ESSIV) += essiv.o
  40 +obj-$(CONFIG_CRYPTO_CURVE25519) += curve25519-generic.o
  41
  42  ecdh_generic-y += ecdh.o
  43  ecdh_generic-y += ecdh_helper.o
  44 --- /dev/null
  45 +++ b/crypto/curve25519-generic.c
  46 @@ -0,0 +1,90 @@
  47 +// SPDX-License-Identifier: GPL-2.0-or-later
  48 +
  49 +#include <crypto/curve25519.h>
  50 +#include <crypto/internal/kpp.h>
  51 +#include <crypto/kpp.h>
  52 +#include <linux/module.h>
  53 +#include <linux/scatterlist.h>
  54 +
  55 +static int curve25519_set_secret(struct crypto_kpp *tfm, const void *buf,
  56 +                                unsigned int len)
  57 +{
  58 +       u8 *secret = kpp_tfm_ctx(tfm);
  59 +
  60 +       if (!len)
  61 +               curve25519_generate_secret(secret);
  62 +       else if (len == CURVE25519_KEY_SIZE &&
  63 +                crypto_memneq(buf, curve25519_null_point, CURVE25519_KEY_SIZE))
  64 +               memcpy(secret, buf, CURVE25519_KEY_SIZE);
  65 +       else
  66 +               return -EINVAL;
  67 +       return 0;
  68 +}
  69 +
  70 +static int curve25519_compute_value(struct kpp_request *req)
  71 +{
  72 +       struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
  73 +       const u8 *secret = kpp_tfm_ctx(tfm);
  74 +       u8 public_key[CURVE25519_KEY_SIZE];
  75 +       u8 buf[CURVE25519_KEY_SIZE];
  76 +       int copied, nbytes;
  77 +       u8 const *bp;
  78 +
  79 +       if (req->src) {
  80 +               copied = sg_copy_to_buffer(req->src,
  81 +                                          sg_nents_for_len(req->src,
  82 +                                                           CURVE25519_KEY_SIZE),
  83 +                                          public_key, CURVE25519_KEY_SIZE);
  84 +               if (copied != CURVE25519_KEY_SIZE)
  85 +                       return -EINVAL;
  86 +               bp = public_key;
  87 +       } else {
  88 +               bp = curve25519_base_point;
  89 +       }
  90 +
  91 +       curve25519_generic(buf, secret, bp);
  92 +
  93 +       /* might want less than we've got */
  94 +       nbytes = min_t(size_t, CURVE25519_KEY_SIZE, req->dst_len);
  95 +       copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
  96 +                                                               nbytes),
  97 +                                    buf, nbytes);
  98 +       if (copied != nbytes)
  99 +               return -EINVAL;
 100 +       return 0;
 101 +}
 102 +
 103 +static unsigned int curve25519_max_size(struct crypto_kpp *tfm)
 104 +{
 105 +       return CURVE25519_KEY_SIZE;
 106 +}
 107 +
 108 +static struct kpp_alg curve25519_alg = {
 109 +       .base.cra_name          = "curve25519",
 110 +       .base.cra_driver_name   = "curve25519-generic",
 111 +       .base.cra_priority      = 100,
 112 +       .base.cra_module        = THIS_MODULE,
 113 +       .base.cra_ctxsize       = CURVE25519_KEY_SIZE,
 114 +
 115 +       .set_secret             = curve25519_set_secret,
 116 +       .generate_public_key    = curve25519_compute_value,
 117 +       .compute_shared_secret  = curve25519_compute_value,
 118 +       .max_size               = curve25519_max_size,
 119 +};
 120 +
 121 +static int curve25519_init(void)
 122 +{
 123 +       return crypto_register_kpp(&curve25519_alg);
 124 +}
 125 +
 126 +static void curve25519_exit(void)
 127 +{
 128 +       crypto_unregister_kpp(&curve25519_alg);
 129 +}
 130 +
 131 +subsys_initcall(curve25519_init);
 132 +module_exit(curve25519_exit);
 133 +
 134 +MODULE_ALIAS_CRYPTO("curve25519");
 135 +MODULE_ALIAS_CRYPTO("curve25519-generic");
 136 +MODULE_LICENSE("GPL");