tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0 OR MIT
2/*
3 * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
4 *
5 * Based on public domain code from Daniel J. Bernstein and Peter Schwabe. This
6 * began from SUPERCOP's curve25519/neon2/scalarmult.s, but has subsequently been
7 * manually reworked for use in kernel space.
8 */
9
10#include <asm/hwcap.h>
11#include <asm/neon.h>
12#include <asm/simd.h>
13#include <crypto/internal/kpp.h>
14#include <crypto/internal/simd.h>
15#include <linux/types.h>
16#include <linux/module.h>
17#include <linux/init.h>
18#include <linux/jump_label.h>
19#include <crypto/curve25519.h>
20
21asmlinkage void curve25519_neon(u8 mypublic[CURVE25519_KEY_SIZE],
22 const u8 secret[CURVE25519_KEY_SIZE],
23 const u8 basepoint[CURVE25519_KEY_SIZE]);
24
25static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
26
27void curve25519_arch(u8 out[CURVE25519_KEY_SIZE],
28 const u8 scalar[CURVE25519_KEY_SIZE],
29 const u8 point[CURVE25519_KEY_SIZE])
30{
31 if (static_branch_likely(&have_neon) && crypto_simd_usable()) {
32 kernel_neon_begin();
33 curve25519_neon(out, scalar, point);
34 kernel_neon_end();
35 } else {
36 curve25519_generic(out, scalar, point);
37 }
38}
39EXPORT_SYMBOL(curve25519_arch);
40
41void curve25519_base_arch(u8 pub[CURVE25519_KEY_SIZE],
42 const u8 secret[CURVE25519_KEY_SIZE])
43{
44 return curve25519_arch(pub, secret, curve25519_base_point);
45}
46EXPORT_SYMBOL(curve25519_base_arch);
47
48static int curve25519_set_secret(struct crypto_kpp *tfm, const void *buf,
49 unsigned int len)
50{
51 u8 *secret = kpp_tfm_ctx(tfm);
52
53 if (!len)
54 curve25519_generate_secret(secret);
55 else if (len == CURVE25519_KEY_SIZE &&
56 crypto_memneq(buf, curve25519_null_point, CURVE25519_KEY_SIZE))
57 memcpy(secret, buf, CURVE25519_KEY_SIZE);
58 else
59 return -EINVAL;
60 return 0;
61}
62
63static int curve25519_compute_value(struct kpp_request *req)
64{
65 struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
66 const u8 *secret = kpp_tfm_ctx(tfm);
67 u8 public_key[CURVE25519_KEY_SIZE];
68 u8 buf[CURVE25519_KEY_SIZE];
69 int copied, nbytes;
70 u8 const *bp;
71
72 if (req->src) {
73 copied = sg_copy_to_buffer(req->src,
74 sg_nents_for_len(req->src,
75 CURVE25519_KEY_SIZE),
76 public_key, CURVE25519_KEY_SIZE);
77 if (copied != CURVE25519_KEY_SIZE)
78 return -EINVAL;
79 bp = public_key;
80 } else {
81 bp = curve25519_base_point;
82 }
83
84 curve25519_arch(buf, secret, bp);
85
86 /* might want less than we've got */
87 nbytes = min_t(size_t, CURVE25519_KEY_SIZE, req->dst_len);
88 copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
89 nbytes),
90 buf, nbytes);
91 if (copied != nbytes)
92 return -EINVAL;
93 return 0;
94}
95
96static unsigned int curve25519_max_size(struct crypto_kpp *tfm)
97{
98 return CURVE25519_KEY_SIZE;
99}
100
101static struct kpp_alg curve25519_alg = {
102 .base.cra_name = "curve25519",
103 .base.cra_driver_name = "curve25519-neon",
104 .base.cra_priority = 200,
105 .base.cra_module = THIS_MODULE,
106 .base.cra_ctxsize = CURVE25519_KEY_SIZE,
107
108 .set_secret = curve25519_set_secret,
109 .generate_public_key = curve25519_compute_value,
110 .compute_shared_secret = curve25519_compute_value,
111 .max_size = curve25519_max_size,
112};
113
114static int __init mod_init(void)
115{
116 if (elf_hwcap & HWCAP_NEON) {
117 static_branch_enable(&have_neon);
118 return IS_REACHABLE(CONFIG_CRYPTO_KPP) ?
119 crypto_register_kpp(&curve25519_alg) : 0;
120 }
121 return 0;
122}
123
124static void __exit mod_exit(void)
125{
126 if (IS_REACHABLE(CONFIG_CRYPTO_KPP) && elf_hwcap & HWCAP_NEON)
127 crypto_unregister_kpp(&curve25519_alg);
128}
129
130module_init(mod_init);
131module_exit(mod_exit);
132
133MODULE_ALIAS_CRYPTO("curve25519");
134MODULE_ALIAS_CRYPTO("curve25519-neon");
135MODULE_LICENSE("GPL v2");