136 lines
3.5 KiB
C
136 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0 OR MIT
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/*
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* Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
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*
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* Based on public domain code from Daniel J. Bernstein and Peter Schwabe. This
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* began from SUPERCOP's curve25519/neon2/scalarmult.s, but has subsequently been
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* manually reworked for use in kernel space.
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*/
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#include <asm/hwcap.h>
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#include <asm/neon.h>
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#include <asm/simd.h>
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#include <crypto/internal/kpp.h>
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#include <linux/types.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/jump_label.h>
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#include <linux/scatterlist.h>
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#include <crypto/curve25519.h>
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asmlinkage void curve25519_neon(u8 mypublic[CURVE25519_KEY_SIZE],
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const u8 secret[CURVE25519_KEY_SIZE],
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const u8 basepoint[CURVE25519_KEY_SIZE]);
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static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
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void curve25519_arch(u8 out[CURVE25519_KEY_SIZE],
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const u8 scalar[CURVE25519_KEY_SIZE],
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const u8 point[CURVE25519_KEY_SIZE])
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{
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if (static_branch_likely(&have_neon) && may_use_simd()) {
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kernel_neon_begin();
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curve25519_neon(out, scalar, point);
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kernel_neon_end();
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} else {
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curve25519_generic(out, scalar, point);
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}
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}
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EXPORT_SYMBOL(curve25519_arch);
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void curve25519_base_arch(u8 pub[CURVE25519_KEY_SIZE],
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const u8 secret[CURVE25519_KEY_SIZE])
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{
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return curve25519_arch(pub, secret, curve25519_base_point);
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}
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EXPORT_SYMBOL(curve25519_base_arch);
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static int curve25519_set_secret(struct crypto_kpp *tfm, const void *buf,
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unsigned int len)
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{
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u8 *secret = kpp_tfm_ctx(tfm);
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if (!len)
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curve25519_generate_secret(secret);
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else if (len == CURVE25519_KEY_SIZE &&
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crypto_memneq(buf, curve25519_null_point, CURVE25519_KEY_SIZE))
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memcpy(secret, buf, CURVE25519_KEY_SIZE);
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else
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return -EINVAL;
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return 0;
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}
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static int curve25519_compute_value(struct kpp_request *req)
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{
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struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
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const u8 *secret = kpp_tfm_ctx(tfm);
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u8 public_key[CURVE25519_KEY_SIZE];
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u8 buf[CURVE25519_KEY_SIZE];
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int copied, nbytes;
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u8 const *bp;
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if (req->src) {
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copied = sg_copy_to_buffer(req->src,
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sg_nents_for_len(req->src,
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CURVE25519_KEY_SIZE),
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public_key, CURVE25519_KEY_SIZE);
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if (copied != CURVE25519_KEY_SIZE)
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return -EINVAL;
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bp = public_key;
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} else {
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bp = curve25519_base_point;
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}
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curve25519_arch(buf, secret, bp);
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/* might want less than we've got */
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nbytes = min_t(size_t, CURVE25519_KEY_SIZE, req->dst_len);
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copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
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nbytes),
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buf, nbytes);
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if (copied != nbytes)
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return -EINVAL;
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return 0;
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}
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static unsigned int curve25519_max_size(struct crypto_kpp *tfm)
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{
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return CURVE25519_KEY_SIZE;
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}
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static struct kpp_alg curve25519_alg = {
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.base.cra_name = "curve25519",
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.base.cra_driver_name = "curve25519-neon",
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.base.cra_priority = 200,
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.base.cra_module = THIS_MODULE,
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.base.cra_ctxsize = CURVE25519_KEY_SIZE,
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.set_secret = curve25519_set_secret,
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.generate_public_key = curve25519_compute_value,
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.compute_shared_secret = curve25519_compute_value,
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.max_size = curve25519_max_size,
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};
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static int __init mod_init(void)
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{
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if (elf_hwcap & HWCAP_NEON) {
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static_branch_enable(&have_neon);
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return IS_REACHABLE(CONFIG_CRYPTO_KPP) ?
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crypto_register_kpp(&curve25519_alg) : 0;
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}
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return 0;
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}
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static void __exit mod_exit(void)
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{
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if (IS_REACHABLE(CONFIG_CRYPTO_KPP) && elf_hwcap & HWCAP_NEON)
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crypto_unregister_kpp(&curve25519_alg);
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}
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module_init(mod_init);
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module_exit(mod_exit);
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MODULE_ALIAS_CRYPTO("curve25519");
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MODULE_ALIAS_CRYPTO("curve25519-neon");
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MODULE_LICENSE("GPL v2");
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