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-rw-r--r--arch/arm/crypto/curve25519-glue.c136
1 files changed, 136 insertions, 0 deletions
diff --git a/arch/arm/crypto/curve25519-glue.c b/arch/arm/crypto/curve25519-glue.c
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+++ b/arch/arm/crypto/curve25519-glue.c
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+// SPDX-License-Identifier: GPL-2.0 OR MIT
+/*
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ *
+ * Based on public domain code from Daniel J. Bernstein and Peter Schwabe. This
+ * began from SUPERCOP's curve25519/neon2/scalarmult.s, but has subsequently been
+ * manually reworked for use in kernel space.
+ */
+
+#include <asm/hwcap.h>
+#include <asm/neon.h>
+#include <asm/simd.h>
+#include <crypto/internal/kpp.h>
+#include <crypto/internal/simd.h>
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/jump_label.h>
+#include <linux/scatterlist.h>
+#include <crypto/curve25519.h>
+
+asmlinkage void curve25519_neon(u8 mypublic[CURVE25519_KEY_SIZE],
+ const u8 secret[CURVE25519_KEY_SIZE],
+ const u8 basepoint[CURVE25519_KEY_SIZE]);
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
+
+void curve25519_arch(u8 out[CURVE25519_KEY_SIZE],
+ const u8 scalar[CURVE25519_KEY_SIZE],
+ const u8 point[CURVE25519_KEY_SIZE])
+{
+ if (static_branch_likely(&have_neon) && crypto_simd_usable()) {
+ kernel_neon_begin();
+ curve25519_neon(out, scalar, point);
+ kernel_neon_end();
+ } else {
+ curve25519_generic(out, scalar, point);
+ }
+}
+EXPORT_SYMBOL(curve25519_arch);
+
+void curve25519_base_arch(u8 pub[CURVE25519_KEY_SIZE],
+ const u8 secret[CURVE25519_KEY_SIZE])
+{
+ return curve25519_arch(pub, secret, curve25519_base_point);
+}
+EXPORT_SYMBOL(curve25519_base_arch);
+
+static int curve25519_set_secret(struct crypto_kpp *tfm, const void *buf,
+ unsigned int len)
+{
+ u8 *secret = kpp_tfm_ctx(tfm);
+
+ if (!len)
+ curve25519_generate_secret(secret);
+ else if (len == CURVE25519_KEY_SIZE &&
+ crypto_memneq(buf, curve25519_null_point, CURVE25519_KEY_SIZE))
+ memcpy(secret, buf, CURVE25519_KEY_SIZE);
+ else
+ return -EINVAL;
+ return 0;
+}
+
+static int curve25519_compute_value(struct kpp_request *req)
+{
+ struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
+ const u8 *secret = kpp_tfm_ctx(tfm);
+ u8 public_key[CURVE25519_KEY_SIZE];
+ u8 buf[CURVE25519_KEY_SIZE];
+ int copied, nbytes;
+ u8 const *bp;
+
+ if (req->src) {
+ copied = sg_copy_to_buffer(req->src,
+ sg_nents_for_len(req->src,
+ CURVE25519_KEY_SIZE),
+ public_key, CURVE25519_KEY_SIZE);
+ if (copied != CURVE25519_KEY_SIZE)
+ return -EINVAL;
+ bp = public_key;
+ } else {
+ bp = curve25519_base_point;
+ }
+
+ curve25519_arch(buf, secret, bp);
+
+ /* might want less than we've got */
+ nbytes = min_t(size_t, CURVE25519_KEY_SIZE, req->dst_len);
+ copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
+ nbytes),
+ buf, nbytes);
+ if (copied != nbytes)
+ return -EINVAL;
+ return 0;
+}
+
+static unsigned int curve25519_max_size(struct crypto_kpp *tfm)
+{
+ return CURVE25519_KEY_SIZE;
+}
+
+static struct kpp_alg curve25519_alg = {
+ .base.cra_name = "curve25519",
+ .base.cra_driver_name = "curve25519-neon",
+ .base.cra_priority = 200,
+ .base.cra_module = THIS_MODULE,
+ .base.cra_ctxsize = CURVE25519_KEY_SIZE,
+
+ .set_secret = curve25519_set_secret,
+ .generate_public_key = curve25519_compute_value,
+ .compute_shared_secret = curve25519_compute_value,
+ .max_size = curve25519_max_size,
+};
+
+static int __init arm_curve25519_init(void)
+{
+ if (elf_hwcap & HWCAP_NEON) {
+ static_branch_enable(&have_neon);
+ return IS_REACHABLE(CONFIG_CRYPTO_KPP) ?
+ crypto_register_kpp(&curve25519_alg) : 0;
+ }
+ return 0;
+}
+
+static void __exit arm_curve25519_exit(void)
+{
+ if (IS_REACHABLE(CONFIG_CRYPTO_KPP) && elf_hwcap & HWCAP_NEON)
+ crypto_unregister_kpp(&curve25519_alg);
+}
+
+module_init(arm_curve25519_init);
+module_exit(arm_curve25519_exit);
+
+MODULE_ALIAS_CRYPTO("curve25519");
+MODULE_ALIAS_CRYPTO("curve25519-neon");
+MODULE_LICENSE("GPL v2");