1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | |
3 | #include <crypto/curve25519.h> |
4 | #include <crypto/internal/kpp.h> |
5 | #include <crypto/kpp.h> |
6 | #include <linux/module.h> |
7 | #include <linux/scatterlist.h> |
8 | |
9 | static int curve25519_set_secret(struct crypto_kpp *tfm, const void *buf, |
10 | unsigned int len) |
11 | { |
12 | u8 *secret = kpp_tfm_ctx(tfm); |
13 | |
14 | if (!len) |
15 | curve25519_generate_secret(secret); |
16 | else if (len == CURVE25519_KEY_SIZE && |
17 | crypto_memneq(a: buf, b: curve25519_null_point, size: CURVE25519_KEY_SIZE)) |
18 | memcpy(secret, buf, CURVE25519_KEY_SIZE); |
19 | else |
20 | return -EINVAL; |
21 | return 0; |
22 | } |
23 | |
24 | static int curve25519_compute_value(struct kpp_request *req) |
25 | { |
26 | struct crypto_kpp *tfm = crypto_kpp_reqtfm(req); |
27 | const u8 *secret = kpp_tfm_ctx(tfm); |
28 | u8 public_key[CURVE25519_KEY_SIZE]; |
29 | u8 buf[CURVE25519_KEY_SIZE]; |
30 | int copied, nbytes; |
31 | u8 const *bp; |
32 | |
33 | if (req->src) { |
34 | copied = sg_copy_to_buffer(sgl: req->src, |
35 | nents: sg_nents_for_len(sg: req->src, |
36 | len: CURVE25519_KEY_SIZE), |
37 | buf: public_key, buflen: CURVE25519_KEY_SIZE); |
38 | if (copied != CURVE25519_KEY_SIZE) |
39 | return -EINVAL; |
40 | bp = public_key; |
41 | } else { |
42 | bp = curve25519_base_point; |
43 | } |
44 | |
45 | curve25519_generic(out: buf, scalar: secret, point: bp); |
46 | |
47 | /* might want less than we've got */ |
48 | nbytes = min_t(size_t, CURVE25519_KEY_SIZE, req->dst_len); |
49 | copied = sg_copy_from_buffer(sgl: req->dst, nents: sg_nents_for_len(sg: req->dst, |
50 | len: nbytes), |
51 | buf, buflen: nbytes); |
52 | if (copied != nbytes) |
53 | return -EINVAL; |
54 | return 0; |
55 | } |
56 | |
57 | static unsigned int curve25519_max_size(struct crypto_kpp *tfm) |
58 | { |
59 | return CURVE25519_KEY_SIZE; |
60 | } |
61 | |
62 | static struct kpp_alg curve25519_alg = { |
63 | .base.cra_name = "curve25519" , |
64 | .base.cra_driver_name = "curve25519-generic" , |
65 | .base.cra_priority = 100, |
66 | .base.cra_module = THIS_MODULE, |
67 | .base.cra_ctxsize = CURVE25519_KEY_SIZE, |
68 | |
69 | .set_secret = curve25519_set_secret, |
70 | .generate_public_key = curve25519_compute_value, |
71 | .compute_shared_secret = curve25519_compute_value, |
72 | .max_size = curve25519_max_size, |
73 | }; |
74 | |
75 | static int __init curve25519_init(void) |
76 | { |
77 | return crypto_register_kpp(alg: &curve25519_alg); |
78 | } |
79 | |
80 | static void __exit curve25519_exit(void) |
81 | { |
82 | crypto_unregister_kpp(alg: &curve25519_alg); |
83 | } |
84 | |
85 | subsys_initcall(curve25519_init); |
86 | module_exit(curve25519_exit); |
87 | |
88 | MODULE_ALIAS_CRYPTO("curve25519" ); |
89 | MODULE_ALIAS_CRYPTO("curve25519-generic" ); |
90 | MODULE_LICENSE("GPL" ); |
91 | |