1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * CMAC: Cipher Block Mode for Authentication |
4 | * |
5 | * Copyright © 2013 Jussi Kivilinna <jussi.kivilinna@iki.fi> |
6 | * |
7 | * Based on work by: |
8 | * Copyright © 2013 Tom St Denis <tstdenis@elliptictech.com> |
9 | * Based on crypto/xcbc.c: |
10 | * Copyright © 2006 USAGI/WIDE Project, |
11 | * Author: Kazunori Miyazawa <miyazawa@linux-ipv6.org> |
12 | */ |
13 | |
14 | #include <crypto/internal/cipher.h> |
15 | #include <crypto/internal/hash.h> |
16 | #include <linux/err.h> |
17 | #include <linux/kernel.h> |
18 | #include <linux/module.h> |
19 | |
20 | /* |
21 | * +------------------------ |
22 | * | <parent tfm> |
23 | * +------------------------ |
24 | * | cmac_tfm_ctx |
25 | * +------------------------ |
26 | * | consts (block size * 2) |
27 | * +------------------------ |
28 | */ |
29 | struct cmac_tfm_ctx { |
30 | struct crypto_cipher *child; |
31 | __be64 consts[]; |
32 | }; |
33 | |
34 | /* |
35 | * +------------------------ |
36 | * | <shash desc> |
37 | * +------------------------ |
38 | * | cmac_desc_ctx |
39 | * +------------------------ |
40 | * | odds (block size) |
41 | * +------------------------ |
42 | * | prev (block size) |
43 | * +------------------------ |
44 | */ |
45 | struct cmac_desc_ctx { |
46 | unsigned int len; |
47 | u8 odds[]; |
48 | }; |
49 | |
50 | static int crypto_cmac_digest_setkey(struct crypto_shash *parent, |
51 | const u8 *inkey, unsigned int keylen) |
52 | { |
53 | struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm: parent); |
54 | unsigned int bs = crypto_shash_blocksize(tfm: parent); |
55 | __be64 *consts = ctx->consts; |
56 | u64 _const[2]; |
57 | int i, err = 0; |
58 | u8 msb_mask, gfmask; |
59 | |
60 | err = crypto_cipher_setkey(tfm: ctx->child, key: inkey, keylen); |
61 | if (err) |
62 | return err; |
63 | |
64 | /* encrypt the zero block */ |
65 | memset(consts, 0, bs); |
66 | crypto_cipher_encrypt_one(tfm: ctx->child, dst: (u8 *)consts, src: (u8 *)consts); |
67 | |
68 | switch (bs) { |
69 | case 16: |
70 | gfmask = 0x87; |
71 | _const[0] = be64_to_cpu(consts[1]); |
72 | _const[1] = be64_to_cpu(consts[0]); |
73 | |
74 | /* gf(2^128) multiply zero-ciphertext with u and u^2 */ |
75 | for (i = 0; i < 4; i += 2) { |
76 | msb_mask = ((s64)_const[1] >> 63) & gfmask; |
77 | _const[1] = (_const[1] << 1) | (_const[0] >> 63); |
78 | _const[0] = (_const[0] << 1) ^ msb_mask; |
79 | |
80 | consts[i + 0] = cpu_to_be64(_const[1]); |
81 | consts[i + 1] = cpu_to_be64(_const[0]); |
82 | } |
83 | |
84 | break; |
85 | case 8: |
86 | gfmask = 0x1B; |
87 | _const[0] = be64_to_cpu(consts[0]); |
88 | |
89 | /* gf(2^64) multiply zero-ciphertext with u and u^2 */ |
90 | for (i = 0; i < 2; i++) { |
91 | msb_mask = ((s64)_const[0] >> 63) & gfmask; |
92 | _const[0] = (_const[0] << 1) ^ msb_mask; |
93 | |
94 | consts[i] = cpu_to_be64(_const[0]); |
95 | } |
96 | |
97 | break; |
98 | } |
99 | |
100 | return 0; |
101 | } |
102 | |
103 | static int crypto_cmac_digest_init(struct shash_desc *pdesc) |
104 | { |
105 | struct cmac_desc_ctx *ctx = shash_desc_ctx(desc: pdesc); |
106 | int bs = crypto_shash_blocksize(tfm: pdesc->tfm); |
107 | u8 *prev = &ctx->odds[bs]; |
108 | |
109 | ctx->len = 0; |
110 | memset(prev, 0, bs); |
111 | |
112 | return 0; |
113 | } |
114 | |
115 | static int crypto_cmac_digest_update(struct shash_desc *pdesc, const u8 *p, |
116 | unsigned int len) |
117 | { |
118 | struct crypto_shash *parent = pdesc->tfm; |
119 | struct cmac_tfm_ctx *tctx = crypto_shash_ctx(tfm: parent); |
120 | struct cmac_desc_ctx *ctx = shash_desc_ctx(desc: pdesc); |
121 | struct crypto_cipher *tfm = tctx->child; |
122 | int bs = crypto_shash_blocksize(tfm: parent); |
123 | u8 *odds = ctx->odds; |
124 | u8 *prev = odds + bs; |
125 | |
126 | /* checking the data can fill the block */ |
127 | if ((ctx->len + len) <= bs) { |
128 | memcpy(odds + ctx->len, p, len); |
129 | ctx->len += len; |
130 | return 0; |
131 | } |
132 | |
133 | /* filling odds with new data and encrypting it */ |
134 | memcpy(odds + ctx->len, p, bs - ctx->len); |
135 | len -= bs - ctx->len; |
136 | p += bs - ctx->len; |
137 | |
138 | crypto_xor(dst: prev, src: odds, size: bs); |
139 | crypto_cipher_encrypt_one(tfm, dst: prev, src: prev); |
140 | |
141 | /* clearing the length */ |
142 | ctx->len = 0; |
143 | |
144 | /* encrypting the rest of data */ |
145 | while (len > bs) { |
146 | crypto_xor(dst: prev, src: p, size: bs); |
147 | crypto_cipher_encrypt_one(tfm, dst: prev, src: prev); |
148 | p += bs; |
149 | len -= bs; |
150 | } |
151 | |
152 | /* keeping the surplus of blocksize */ |
153 | if (len) { |
154 | memcpy(odds, p, len); |
155 | ctx->len = len; |
156 | } |
157 | |
158 | return 0; |
159 | } |
160 | |
161 | static int crypto_cmac_digest_final(struct shash_desc *pdesc, u8 *out) |
162 | { |
163 | struct crypto_shash *parent = pdesc->tfm; |
164 | struct cmac_tfm_ctx *tctx = crypto_shash_ctx(tfm: parent); |
165 | struct cmac_desc_ctx *ctx = shash_desc_ctx(desc: pdesc); |
166 | struct crypto_cipher *tfm = tctx->child; |
167 | int bs = crypto_shash_blocksize(tfm: parent); |
168 | u8 *odds = ctx->odds; |
169 | u8 *prev = odds + bs; |
170 | unsigned int offset = 0; |
171 | |
172 | if (ctx->len != bs) { |
173 | unsigned int rlen; |
174 | u8 *p = odds + ctx->len; |
175 | |
176 | *p = 0x80; |
177 | p++; |
178 | |
179 | rlen = bs - ctx->len - 1; |
180 | if (rlen) |
181 | memset(p, 0, rlen); |
182 | |
183 | offset += bs; |
184 | } |
185 | |
186 | crypto_xor(dst: prev, src: odds, size: bs); |
187 | crypto_xor(dst: prev, src: (const u8 *)tctx->consts + offset, size: bs); |
188 | |
189 | crypto_cipher_encrypt_one(tfm, dst: out, src: prev); |
190 | |
191 | return 0; |
192 | } |
193 | |
194 | static int cmac_init_tfm(struct crypto_shash *tfm) |
195 | { |
196 | struct shash_instance *inst = shash_alg_instance(shash: tfm); |
197 | struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm); |
198 | struct crypto_cipher_spawn *spawn; |
199 | struct crypto_cipher *cipher; |
200 | |
201 | spawn = shash_instance_ctx(inst); |
202 | cipher = crypto_spawn_cipher(spawn); |
203 | if (IS_ERR(ptr: cipher)) |
204 | return PTR_ERR(ptr: cipher); |
205 | |
206 | ctx->child = cipher; |
207 | |
208 | return 0; |
209 | } |
210 | |
211 | static int cmac_clone_tfm(struct crypto_shash *tfm, struct crypto_shash *otfm) |
212 | { |
213 | struct cmac_tfm_ctx *octx = crypto_shash_ctx(tfm: otfm); |
214 | struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm); |
215 | struct crypto_cipher *cipher; |
216 | |
217 | cipher = crypto_clone_cipher(cipher: octx->child); |
218 | if (IS_ERR(ptr: cipher)) |
219 | return PTR_ERR(ptr: cipher); |
220 | |
221 | ctx->child = cipher; |
222 | |
223 | return 0; |
224 | } |
225 | |
226 | static void cmac_exit_tfm(struct crypto_shash *tfm) |
227 | { |
228 | struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm); |
229 | crypto_free_cipher(tfm: ctx->child); |
230 | } |
231 | |
232 | static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb) |
233 | { |
234 | struct shash_instance *inst; |
235 | struct crypto_cipher_spawn *spawn; |
236 | struct crypto_alg *alg; |
237 | u32 mask; |
238 | int err; |
239 | |
240 | err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, mask_ret: &mask); |
241 | if (err) |
242 | return err; |
243 | |
244 | inst = kzalloc(size: sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); |
245 | if (!inst) |
246 | return -ENOMEM; |
247 | spawn = shash_instance_ctx(inst); |
248 | |
249 | err = crypto_grab_cipher(spawn, inst: shash_crypto_instance(inst), |
250 | name: crypto_attr_alg_name(rta: tb[1]), type: 0, mask); |
251 | if (err) |
252 | goto err_free_inst; |
253 | alg = crypto_spawn_cipher_alg(spawn); |
254 | |
255 | switch (alg->cra_blocksize) { |
256 | case 16: |
257 | case 8: |
258 | break; |
259 | default: |
260 | err = -EINVAL; |
261 | goto err_free_inst; |
262 | } |
263 | |
264 | err = crypto_inst_setname(inst: shash_crypto_instance(inst), name: tmpl->name, alg); |
265 | if (err) |
266 | goto err_free_inst; |
267 | |
268 | inst->alg.base.cra_priority = alg->cra_priority; |
269 | inst->alg.base.cra_blocksize = alg->cra_blocksize; |
270 | inst->alg.base.cra_ctxsize = sizeof(struct cmac_tfm_ctx) + |
271 | alg->cra_blocksize * 2; |
272 | |
273 | inst->alg.digestsize = alg->cra_blocksize; |
274 | inst->alg.descsize = sizeof(struct cmac_desc_ctx) + |
275 | alg->cra_blocksize * 2; |
276 | inst->alg.init = crypto_cmac_digest_init; |
277 | inst->alg.update = crypto_cmac_digest_update; |
278 | inst->alg.final = crypto_cmac_digest_final; |
279 | inst->alg.setkey = crypto_cmac_digest_setkey; |
280 | inst->alg.init_tfm = cmac_init_tfm; |
281 | inst->alg.clone_tfm = cmac_clone_tfm; |
282 | inst->alg.exit_tfm = cmac_exit_tfm; |
283 | |
284 | inst->free = shash_free_singlespawn_instance; |
285 | |
286 | err = shash_register_instance(tmpl, inst); |
287 | if (err) { |
288 | err_free_inst: |
289 | shash_free_singlespawn_instance(inst); |
290 | } |
291 | return err; |
292 | } |
293 | |
294 | static struct crypto_template crypto_cmac_tmpl = { |
295 | .name = "cmac" , |
296 | .create = cmac_create, |
297 | .module = THIS_MODULE, |
298 | }; |
299 | |
300 | static int __init crypto_cmac_module_init(void) |
301 | { |
302 | return crypto_register_template(tmpl: &crypto_cmac_tmpl); |
303 | } |
304 | |
305 | static void __exit crypto_cmac_module_exit(void) |
306 | { |
307 | crypto_unregister_template(tmpl: &crypto_cmac_tmpl); |
308 | } |
309 | |
310 | subsys_initcall(crypto_cmac_module_init); |
311 | module_exit(crypto_cmac_module_exit); |
312 | |
313 | MODULE_LICENSE("GPL" ); |
314 | MODULE_DESCRIPTION("CMAC keyed hash algorithm" ); |
315 | MODULE_ALIAS_CRYPTO("cmac" ); |
316 | MODULE_IMPORT_NS(CRYPTO_INTERNAL); |
317 | |