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8394bfec51
For glue code that's used by Zinc, the actual Crypto API functions might not necessarily exist, and don't need to exist either. Before this patch, there are valid build configurations that lead to a unbuildable kernel. This fixes it to conditionalize those symbols on the existence of the proper config entry. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Acked-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
129 lines
3.3 KiB
C
129 lines
3.3 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 <crypto/internal/simd.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 <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) && crypto_simd_usable()) {
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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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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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