Commit | Line | Data |
---|---|---|
2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
3c4b2390 SB |
2 | /* ECDH key-agreement protocol |
3 | * | |
4 | * Copyright (c) 2016, Intel Corporation | |
5 | * Authors: Salvator Benedetto <salvatore.benedetto@intel.com> | |
3c4b2390 SB |
6 | */ |
7 | ||
8 | #include <linux/module.h> | |
9 | #include <crypto/internal/kpp.h> | |
10 | #include <crypto/kpp.h> | |
11 | #include <crypto/ecdh.h> | |
12 | #include <linux/scatterlist.h> | |
13 | #include "ecc.h" | |
14 | ||
15 | struct ecdh_ctx { | |
16 | unsigned int curve_id; | |
17 | unsigned int ndigits; | |
18 | u64 private_key[ECC_MAX_DIGITS]; | |
3c4b2390 SB |
19 | }; |
20 | ||
21 | static inline struct ecdh_ctx *ecdh_get_ctx(struct crypto_kpp *tfm) | |
22 | { | |
23 | return kpp_tfm_ctx(tfm); | |
24 | } | |
25 | ||
26 | static unsigned int ecdh_supported_curve(unsigned int curve_id) | |
27 | { | |
28 | switch (curve_id) { | |
d5c3b178 KC |
29 | case ECC_CURVE_NIST_P192: return ECC_CURVE_NIST_P192_DIGITS; |
30 | case ECC_CURVE_NIST_P256: return ECC_CURVE_NIST_P256_DIGITS; | |
3c4b2390 SB |
31 | default: return 0; |
32 | } | |
33 | } | |
34 | ||
5527dfb6 EB |
35 | static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf, |
36 | unsigned int len) | |
3c4b2390 SB |
37 | { |
38 | struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); | |
39 | struct ecdh params; | |
40 | unsigned int ndigits; | |
41 | ||
42 | if (crypto_ecdh_decode_key(buf, len, ¶ms) < 0) | |
43 | return -EINVAL; | |
44 | ||
45 | ndigits = ecdh_supported_curve(params.curve_id); | |
46 | if (!ndigits) | |
47 | return -EINVAL; | |
48 | ||
49 | ctx->curve_id = params.curve_id; | |
50 | ctx->ndigits = ndigits; | |
51 | ||
6755fd26 TDA |
52 | if (!params.key || !params.key_size) |
53 | return ecc_gen_privkey(ctx->curve_id, ctx->ndigits, | |
54 | ctx->private_key); | |
55 | ||
3c4b2390 SB |
56 | memcpy(ctx->private_key, params.key, params.key_size); |
57 | ||
17858b14 AB |
58 | if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits, |
59 | ctx->private_key, params.key_size) < 0) { | |
60 | memzero_explicit(ctx->private_key, params.key_size); | |
61 | return -EINVAL; | |
62 | } | |
3c4b2390 SB |
63 | return 0; |
64 | } | |
65 | ||
66 | static int ecdh_compute_value(struct kpp_request *req) | |
67 | { | |
3c4b2390 SB |
68 | struct crypto_kpp *tfm = crypto_kpp_reqtfm(req); |
69 | struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); | |
952035ba TDA |
70 | u64 *public_key; |
71 | u64 *shared_secret = NULL; | |
3c4b2390 | 72 | void *buf; |
952035ba TDA |
73 | size_t copied, nbytes, public_key_sz; |
74 | int ret = -ENOMEM; | |
3c4b2390 SB |
75 | |
76 | nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT; | |
952035ba TDA |
77 | /* Public part is a point thus it has both coordinates */ |
78 | public_key_sz = 2 * nbytes; | |
79 | ||
80 | public_key = kmalloc(public_key_sz, GFP_KERNEL); | |
81 | if (!public_key) | |
82 | return -ENOMEM; | |
3c4b2390 SB |
83 | |
84 | if (req->src) { | |
952035ba TDA |
85 | shared_secret = kmalloc(nbytes, GFP_KERNEL); |
86 | if (!shared_secret) | |
87 | goto free_pubkey; | |
88 | ||
95ec01ba JB |
89 | /* from here on it's invalid parameters */ |
90 | ret = -EINVAL; | |
91 | ||
92 | /* must have exactly two points to be on the curve */ | |
93 | if (public_key_sz != req->src_len) | |
94 | goto free_all; | |
95 | ||
96 | copied = sg_copy_to_buffer(req->src, | |
97 | sg_nents_for_len(req->src, | |
98 | public_key_sz), | |
99 | public_key, public_key_sz); | |
100 | if (copied != public_key_sz) | |
952035ba | 101 | goto free_all; |
3c4b2390 | 102 | |
8f44df15 | 103 | ret = crypto_ecdh_shared_secret(ctx->curve_id, ctx->ndigits, |
952035ba TDA |
104 | ctx->private_key, public_key, |
105 | shared_secret); | |
3c4b2390 | 106 | |
952035ba | 107 | buf = shared_secret; |
3c4b2390 | 108 | } else { |
7380c56d | 109 | ret = ecc_make_pub_key(ctx->curve_id, ctx->ndigits, |
952035ba TDA |
110 | ctx->private_key, public_key); |
111 | buf = public_key; | |
112 | nbytes = public_key_sz; | |
3c4b2390 SB |
113 | } |
114 | ||
115 | if (ret < 0) | |
952035ba | 116 | goto free_all; |
3c4b2390 | 117 | |
95ec01ba JB |
118 | /* might want less than we've got */ |
119 | nbytes = min_t(size_t, nbytes, req->dst_len); | |
120 | copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst, | |
121 | nbytes), | |
122 | buf, nbytes); | |
3c4b2390 | 123 | if (copied != nbytes) |
952035ba | 124 | ret = -EINVAL; |
3c4b2390 | 125 | |
952035ba TDA |
126 | /* fall through */ |
127 | free_all: | |
453431a5 | 128 | kfree_sensitive(shared_secret); |
952035ba TDA |
129 | free_pubkey: |
130 | kfree(public_key); | |
3c4b2390 SB |
131 | return ret; |
132 | } | |
133 | ||
d0efb48b | 134 | static unsigned int ecdh_max_size(struct crypto_kpp *tfm) |
3c4b2390 SB |
135 | { |
136 | struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); | |
3c4b2390 | 137 | |
d0efb48b TDA |
138 | /* Public key is made of two coordinates, add one to the left shift */ |
139 | return ctx->ndigits << (ECC_DIGITS_TO_BYTES_SHIFT + 1); | |
3c4b2390 SB |
140 | } |
141 | ||
3c4b2390 SB |
142 | static struct kpp_alg ecdh = { |
143 | .set_secret = ecdh_set_secret, | |
144 | .generate_public_key = ecdh_compute_value, | |
145 | .compute_shared_secret = ecdh_compute_value, | |
146 | .max_size = ecdh_max_size, | |
3c4b2390 SB |
147 | .base = { |
148 | .cra_name = "ecdh", | |
149 | .cra_driver_name = "ecdh-generic", | |
150 | .cra_priority = 100, | |
151 | .cra_module = THIS_MODULE, | |
152 | .cra_ctxsize = sizeof(struct ecdh_ctx), | |
153 | }, | |
154 | }; | |
155 | ||
156 | static int ecdh_init(void) | |
157 | { | |
158 | return crypto_register_kpp(&ecdh); | |
159 | } | |
160 | ||
161 | static void ecdh_exit(void) | |
162 | { | |
163 | crypto_unregister_kpp(&ecdh); | |
164 | } | |
165 | ||
c4741b23 | 166 | subsys_initcall(ecdh_init); |
3c4b2390 SB |
167 | module_exit(ecdh_exit); |
168 | MODULE_ALIAS_CRYPTO("ecdh"); | |
169 | MODULE_LICENSE("GPL"); | |
170 | MODULE_DESCRIPTION("ECDH generic algorithm"); |