2 * aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions
4 * Copyright (C) 2013 - 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
13 #include <asm/unaligned.h>
14 #include <crypto/aes.h>
15 #include <crypto/scatterwalk.h>
16 #include <crypto/internal/aead.h>
17 #include <crypto/internal/skcipher.h>
18 #include <linux/module.h>
20 #include "aes-ce-setkey.h"
22 static int num_rounds(struct crypto_aes_ctx *ctx)
25 * # of rounds specified by AES:
26 * 128 bit key 10 rounds
27 * 192 bit key 12 rounds
28 * 256 bit key 14 rounds
29 * => n byte key => 6 + (n/4) rounds
31 return 6 + ctx->key_length / 4;
34 asmlinkage void ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes,
35 u32 *macp, u32 const rk[], u32 rounds);
37 asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes,
38 u32 const rk[], u32 rounds, u8 mac[],
41 asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes,
42 u32 const rk[], u32 rounds, u8 mac[],
45 asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[],
48 asmlinkage void __aes_arm64_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
50 static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key,
53 struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);
56 ret = ce_aes_expandkey(ctx, in_key, key_len);
60 tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
64 static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
66 if ((authsize & 1) || authsize < 4)
71 static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
73 struct crypto_aead *aead = crypto_aead_reqtfm(req);
74 __be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8];
75 u32 l = req->iv[0] + 1;
77 /* verify that CCM dimension 'L' is set correctly in the IV */
81 /* verify that msglen can in fact be represented in L bytes */
82 if (l < 4 && msglen >> (8 * l))
86 * Even if the CCM spec allows L values of up to 8, the Linux cryptoapi
87 * uses a u32 type to represent msglen so the top 4 bytes are always 0.
90 n[1] = cpu_to_be32(msglen);
92 memcpy(maciv, req->iv, AES_BLOCK_SIZE - l);
95 * Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C)
96 * - bits 0..2 : max # of bytes required to represent msglen, minus 1
97 * (already set by caller)
98 * - bits 3..5 : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc)
99 * - bit 6 : indicates presence of authenticate-only data
101 maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2;
105 memset(&req->iv[AES_BLOCK_SIZE - l], 0, l);
109 static void ccm_update_mac(struct crypto_aes_ctx *key, u8 mac[], u8 const in[],
110 u32 abytes, u32 *macp)
112 if (may_use_simd()) {
114 ce_aes_ccm_auth_data(mac, in, abytes, macp, key->key_enc,
118 if (*macp > 0 && *macp < AES_BLOCK_SIZE) {
119 int added = min(abytes, AES_BLOCK_SIZE - *macp);
121 crypto_xor(&mac[*macp], in, added);
128 while (abytes >= AES_BLOCK_SIZE) {
129 __aes_arm64_encrypt(key->key_enc, mac, mac,
131 crypto_xor(mac, in, AES_BLOCK_SIZE);
133 in += AES_BLOCK_SIZE;
134 abytes -= AES_BLOCK_SIZE;
138 __aes_arm64_encrypt(key->key_enc, mac, mac,
140 crypto_xor(mac, in, abytes);
146 static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
148 struct crypto_aead *aead = crypto_aead_reqtfm(req);
149 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
150 struct __packed { __be16 l; __be32 h; u16 len; } ltag;
151 struct scatter_walk walk;
152 u32 len = req->assoclen;
155 /* prepend the AAD with a length tag */
157 ltag.l = cpu_to_be16(len);
160 ltag.l = cpu_to_be16(0xfffe);
161 put_unaligned_be32(len, <ag.h);
165 ccm_update_mac(ctx, mac, (u8 *)<ag, ltag.len, &macp);
166 scatterwalk_start(&walk, req->src);
169 u32 n = scatterwalk_clamp(&walk, len);
173 scatterwalk_start(&walk, sg_next(walk.sg));
174 n = scatterwalk_clamp(&walk, len);
176 p = scatterwalk_map(&walk);
177 ccm_update_mac(ctx, mac, p, n, &macp);
180 scatterwalk_unmap(p);
181 scatterwalk_advance(&walk, n);
182 scatterwalk_done(&walk, 0, len);
186 static int ccm_crypt_fallback(struct skcipher_walk *walk, u8 mac[], u8 iv0[],
187 struct crypto_aes_ctx *ctx, bool enc)
189 u8 buf[AES_BLOCK_SIZE];
192 while (walk->nbytes) {
193 int blocks = walk->nbytes / AES_BLOCK_SIZE;
194 u32 tail = walk->nbytes % AES_BLOCK_SIZE;
195 u8 *dst = walk->dst.virt.addr;
196 u8 *src = walk->src.virt.addr;
197 u32 nbytes = walk->nbytes;
199 if (nbytes == walk->total && tail > 0) {
205 u32 bsize = AES_BLOCK_SIZE;
207 if (nbytes < AES_BLOCK_SIZE)
210 crypto_inc(walk->iv, AES_BLOCK_SIZE);
211 __aes_arm64_encrypt(ctx->key_enc, buf, walk->iv,
213 __aes_arm64_encrypt(ctx->key_enc, mac, mac,
216 crypto_xor(mac, src, bsize);
217 crypto_xor_cpy(dst, src, buf, bsize);
219 crypto_xor(mac, dst, bsize);
225 err = skcipher_walk_done(walk, tail);
229 __aes_arm64_encrypt(ctx->key_enc, buf, iv0, num_rounds(ctx));
230 __aes_arm64_encrypt(ctx->key_enc, mac, mac, num_rounds(ctx));
231 crypto_xor(mac, buf, AES_BLOCK_SIZE);
236 static int ccm_encrypt(struct aead_request *req)
238 struct crypto_aead *aead = crypto_aead_reqtfm(req);
239 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
240 struct skcipher_walk walk;
241 u8 __aligned(8) mac[AES_BLOCK_SIZE];
242 u8 buf[AES_BLOCK_SIZE];
243 u32 len = req->cryptlen;
246 err = ccm_init_mac(req, mac, len);
251 ccm_calculate_auth_mac(req, mac);
253 /* preserve the original iv for the final round */
254 memcpy(buf, req->iv, AES_BLOCK_SIZE);
256 err = skcipher_walk_aead_encrypt(&walk, req, false);
258 if (may_use_simd()) {
259 while (walk.nbytes) {
260 u32 tail = walk.nbytes % AES_BLOCK_SIZE;
262 if (walk.nbytes == walk.total)
266 ce_aes_ccm_encrypt(walk.dst.virt.addr,
268 walk.nbytes - tail, ctx->key_enc,
269 num_rounds(ctx), mac, walk.iv);
272 err = skcipher_walk_done(&walk, tail);
276 ce_aes_ccm_final(mac, buf, ctx->key_enc,
281 err = ccm_crypt_fallback(&walk, mac, buf, ctx, true);
286 /* copy authtag to end of dst */
287 scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen,
288 crypto_aead_authsize(aead), 1);
293 static int ccm_decrypt(struct aead_request *req)
295 struct crypto_aead *aead = crypto_aead_reqtfm(req);
296 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
297 unsigned int authsize = crypto_aead_authsize(aead);
298 struct skcipher_walk walk;
299 u8 __aligned(8) mac[AES_BLOCK_SIZE];
300 u8 buf[AES_BLOCK_SIZE];
301 u32 len = req->cryptlen - authsize;
304 err = ccm_init_mac(req, mac, len);
309 ccm_calculate_auth_mac(req, mac);
311 /* preserve the original iv for the final round */
312 memcpy(buf, req->iv, AES_BLOCK_SIZE);
314 err = skcipher_walk_aead_decrypt(&walk, req, false);
316 if (may_use_simd()) {
317 while (walk.nbytes) {
318 u32 tail = walk.nbytes % AES_BLOCK_SIZE;
320 if (walk.nbytes == walk.total)
324 ce_aes_ccm_decrypt(walk.dst.virt.addr,
326 walk.nbytes - tail, ctx->key_enc,
327 num_rounds(ctx), mac, walk.iv);
330 err = skcipher_walk_done(&walk, tail);
334 ce_aes_ccm_final(mac, buf, ctx->key_enc,
339 err = ccm_crypt_fallback(&walk, mac, buf, ctx, false);
345 /* compare calculated auth tag with the stored one */
346 scatterwalk_map_and_copy(buf, req->src,
347 req->assoclen + req->cryptlen - authsize,
350 if (crypto_memneq(mac, buf, authsize))
355 static struct aead_alg ccm_aes_alg = {
357 .cra_name = "ccm(aes)",
358 .cra_driver_name = "ccm-aes-ce",
361 .cra_ctxsize = sizeof(struct crypto_aes_ctx),
362 .cra_module = THIS_MODULE,
364 .ivsize = AES_BLOCK_SIZE,
365 .chunksize = AES_BLOCK_SIZE,
366 .maxauthsize = AES_BLOCK_SIZE,
367 .setkey = ccm_setkey,
368 .setauthsize = ccm_setauthsize,
369 .encrypt = ccm_encrypt,
370 .decrypt = ccm_decrypt,
373 static int __init aes_mod_init(void)
375 if (!(elf_hwcap & HWCAP_AES))
377 return crypto_register_aead(&ccm_aes_alg);
380 static void __exit aes_mod_exit(void)
382 crypto_unregister_aead(&ccm_aes_alg);
385 module_init(aes_mod_init);
386 module_exit(aes_mod_exit);
388 MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
389 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
390 MODULE_LICENSE("GPL v2");
391 MODULE_ALIAS_CRYPTO("ccm(aes)");