1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * AMD Cryptographic Coprocessor (CCP) AES XTS crypto API support
4  *
5  * Copyright (C) 2013,2017 Advanced Micro Devices, Inc.
6  *
7  * Author: Gary R Hook <gary.hook@amd.com>
8  * Author: Tom Lendacky <thomas.lendacky@amd.com>
9  */
10 
11 #include <linux/module.h>
12 #include <linux/sched.h>
13 #include <linux/delay.h>
14 #include <linux/scatterlist.h>
15 #include <crypto/aes.h>
16 #include <crypto/xts.h>
17 #include <crypto/internal/skcipher.h>
18 #include <crypto/scatterwalk.h>
19 
20 #include "ccp-crypto.h"
21 
22 struct ccp_aes_xts_def {
23 	const char *name;
24 	const char *drv_name;
25 };
26 
27 static const struct ccp_aes_xts_def aes_xts_algs[] = {
28 	{
29 		.name		= "xts(aes)",
30 		.drv_name	= "xts-aes-ccp",
31 	},
32 };
33 
34 struct ccp_unit_size_map {
35 	unsigned int size;
36 	u32 value;
37 };
38 
39 static struct ccp_unit_size_map xts_unit_sizes[] = {
40 	{
41 		.size   = 16,
42 		.value	= CCP_XTS_AES_UNIT_SIZE_16,
43 	},
44 	{
45 		.size   = 512,
46 		.value	= CCP_XTS_AES_UNIT_SIZE_512,
47 	},
48 	{
49 		.size   = 1024,
50 		.value	= CCP_XTS_AES_UNIT_SIZE_1024,
51 	},
52 	{
53 		.size   = 2048,
54 		.value	= CCP_XTS_AES_UNIT_SIZE_2048,
55 	},
56 	{
57 		.size   = 4096,
58 		.value	= CCP_XTS_AES_UNIT_SIZE_4096,
59 	},
60 };
61 
62 static int ccp_aes_xts_complete(struct crypto_async_request *async_req, int ret)
63 {
64 	struct skcipher_request *req = skcipher_request_cast(async_req);
65 	struct ccp_aes_req_ctx *rctx = skcipher_request_ctx(req);
66 
67 	if (ret)
68 		return ret;
69 
70 	memcpy(req->iv, rctx->iv, AES_BLOCK_SIZE);
71 
72 	return 0;
73 }
74 
75 static int ccp_aes_xts_setkey(struct crypto_skcipher *tfm, const u8 *key,
76 			      unsigned int key_len)
77 {
78 	struct ccp_ctx *ctx = crypto_skcipher_ctx(tfm);
79 	unsigned int ccpversion = ccp_version();
80 	int ret;
81 
82 	ret = xts_verify_key(tfm, key, key_len);
83 	if (ret)
84 		return ret;
85 
86 	/* Version 3 devices support 128-bit keys; version 5 devices can
87 	 * accommodate 128- and 256-bit keys.
88 	 */
89 	switch (key_len) {
90 	case AES_KEYSIZE_128 * 2:
91 		memcpy(ctx->u.aes.key, key, key_len);
92 		break;
93 	case AES_KEYSIZE_256 * 2:
94 		if (ccpversion > CCP_VERSION(3, 0))
95 			memcpy(ctx->u.aes.key, key, key_len);
96 		break;
97 	}
98 	ctx->u.aes.key_len = key_len / 2;
99 	sg_init_one(&ctx->u.aes.key_sg, ctx->u.aes.key, key_len);
100 
101 	return crypto_sync_skcipher_setkey(ctx->u.aes.tfm_skcipher, key, key_len);
102 }
103 
104 static int ccp_aes_xts_crypt(struct skcipher_request *req,
105 			     unsigned int encrypt)
106 {
107 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
108 	struct ccp_ctx *ctx = crypto_skcipher_ctx(tfm);
109 	struct ccp_aes_req_ctx *rctx = skcipher_request_ctx(req);
110 	unsigned int ccpversion = ccp_version();
111 	unsigned int fallback = 0;
112 	unsigned int unit;
113 	u32 unit_size;
114 	int ret;
115 
116 	if (!ctx->u.aes.key_len)
117 		return -EINVAL;
118 
119 	if (!req->iv)
120 		return -EINVAL;
121 
122 	/* Check conditions under which the CCP can fulfill a request. The
123 	 * device can handle input plaintext of a length that is a multiple
124 	 * of the unit_size, bug the crypto implementation only supports
125 	 * the unit_size being equal to the input length. This limits the
126 	 * number of scenarios we can handle.
127 	 */
128 	unit_size = CCP_XTS_AES_UNIT_SIZE__LAST;
129 	for (unit = 0; unit < ARRAY_SIZE(xts_unit_sizes); unit++) {
130 		if (req->cryptlen == xts_unit_sizes[unit].size) {
131 			unit_size = unit;
132 			break;
133 		}
134 	}
135 	/* The CCP has restrictions on block sizes. Also, a version 3 device
136 	 * only supports AES-128 operations; version 5 CCPs support both
137 	 * AES-128 and -256 operations.
138 	 */
139 	if (unit_size == CCP_XTS_AES_UNIT_SIZE__LAST)
140 		fallback = 1;
141 	if ((ccpversion < CCP_VERSION(5, 0)) &&
142 	    (ctx->u.aes.key_len != AES_KEYSIZE_128))
143 		fallback = 1;
144 	if ((ctx->u.aes.key_len != AES_KEYSIZE_128) &&
145 	    (ctx->u.aes.key_len != AES_KEYSIZE_256))
146 		fallback = 1;
147 	if (fallback) {
148 		SYNC_SKCIPHER_REQUEST_ON_STACK(subreq,
149 					       ctx->u.aes.tfm_skcipher);
150 
151 		/* Use the fallback to process the request for any
152 		 * unsupported unit sizes or key sizes
153 		 */
154 		skcipher_request_set_sync_tfm(subreq, ctx->u.aes.tfm_skcipher);
155 		skcipher_request_set_callback(subreq, req->base.flags,
156 					      NULL, NULL);
157 		skcipher_request_set_crypt(subreq, req->src, req->dst,
158 					   req->cryptlen, req->iv);
159 		ret = encrypt ? crypto_skcipher_encrypt(subreq) :
160 				crypto_skcipher_decrypt(subreq);
161 		skcipher_request_zero(subreq);
162 		return ret;
163 	}
164 
165 	memcpy(rctx->iv, req->iv, AES_BLOCK_SIZE);
166 	sg_init_one(&rctx->iv_sg, rctx->iv, AES_BLOCK_SIZE);
167 
168 	memset(&rctx->cmd, 0, sizeof(rctx->cmd));
169 	INIT_LIST_HEAD(&rctx->cmd.entry);
170 	rctx->cmd.engine = CCP_ENGINE_XTS_AES_128;
171 	rctx->cmd.u.xts.type = CCP_AES_TYPE_128;
172 	rctx->cmd.u.xts.action = (encrypt) ? CCP_AES_ACTION_ENCRYPT
173 					   : CCP_AES_ACTION_DECRYPT;
174 	rctx->cmd.u.xts.unit_size = unit_size;
175 	rctx->cmd.u.xts.key = &ctx->u.aes.key_sg;
176 	rctx->cmd.u.xts.key_len = ctx->u.aes.key_len;
177 	rctx->cmd.u.xts.iv = &rctx->iv_sg;
178 	rctx->cmd.u.xts.iv_len = AES_BLOCK_SIZE;
179 	rctx->cmd.u.xts.src = req->src;
180 	rctx->cmd.u.xts.src_len = req->cryptlen;
181 	rctx->cmd.u.xts.dst = req->dst;
182 
183 	ret = ccp_crypto_enqueue_request(&req->base, &rctx->cmd);
184 
185 	return ret;
186 }
187 
188 static int ccp_aes_xts_encrypt(struct skcipher_request *req)
189 {
190 	return ccp_aes_xts_crypt(req, 1);
191 }
192 
193 static int ccp_aes_xts_decrypt(struct skcipher_request *req)
194 {
195 	return ccp_aes_xts_crypt(req, 0);
196 }
197 
198 static int ccp_aes_xts_init_tfm(struct crypto_skcipher *tfm)
199 {
200 	struct ccp_ctx *ctx = crypto_skcipher_ctx(tfm);
201 	struct crypto_sync_skcipher *fallback_tfm;
202 
203 	ctx->complete = ccp_aes_xts_complete;
204 	ctx->u.aes.key_len = 0;
205 
206 	fallback_tfm = crypto_alloc_sync_skcipher("xts(aes)", 0,
207 					     CRYPTO_ALG_ASYNC |
208 					     CRYPTO_ALG_NEED_FALLBACK);
209 	if (IS_ERR(fallback_tfm)) {
210 		pr_warn("could not load fallback driver xts(aes)\n");
211 		return PTR_ERR(fallback_tfm);
212 	}
213 	ctx->u.aes.tfm_skcipher = fallback_tfm;
214 
215 	crypto_skcipher_set_reqsize(tfm, sizeof(struct ccp_aes_req_ctx));
216 
217 	return 0;
218 }
219 
220 static void ccp_aes_xts_exit_tfm(struct crypto_skcipher *tfm)
221 {
222 	struct ccp_ctx *ctx = crypto_skcipher_ctx(tfm);
223 
224 	crypto_free_sync_skcipher(ctx->u.aes.tfm_skcipher);
225 }
226 
227 static int ccp_register_aes_xts_alg(struct list_head *head,
228 				    const struct ccp_aes_xts_def *def)
229 {
230 	struct ccp_crypto_skcipher_alg *ccp_alg;
231 	struct skcipher_alg *alg;
232 	int ret;
233 
234 	ccp_alg = kzalloc(sizeof(*ccp_alg), GFP_KERNEL);
235 	if (!ccp_alg)
236 		return -ENOMEM;
237 
238 	INIT_LIST_HEAD(&ccp_alg->entry);
239 
240 	alg = &ccp_alg->alg;
241 
242 	snprintf(alg->base.cra_name, CRYPTO_MAX_ALG_NAME, "%s", def->name);
243 	snprintf(alg->base.cra_driver_name, CRYPTO_MAX_ALG_NAME, "%s",
244 		 def->drv_name);
245 	alg->base.cra_flags	= CRYPTO_ALG_ASYNC |
246 				  CRYPTO_ALG_KERN_DRIVER_ONLY |
247 				  CRYPTO_ALG_NEED_FALLBACK;
248 	alg->base.cra_blocksize	= AES_BLOCK_SIZE;
249 	alg->base.cra_ctxsize	= sizeof(struct ccp_ctx);
250 	alg->base.cra_priority	= CCP_CRA_PRIORITY;
251 	alg->base.cra_module	= THIS_MODULE;
252 
253 	alg->setkey		= ccp_aes_xts_setkey;
254 	alg->encrypt		= ccp_aes_xts_encrypt;
255 	alg->decrypt		= ccp_aes_xts_decrypt;
256 	alg->min_keysize	= AES_MIN_KEY_SIZE * 2;
257 	alg->max_keysize	= AES_MAX_KEY_SIZE * 2;
258 	alg->ivsize		= AES_BLOCK_SIZE;
259 	alg->init		= ccp_aes_xts_init_tfm;
260 	alg->exit		= ccp_aes_xts_exit_tfm;
261 
262 	ret = crypto_register_skcipher(alg);
263 	if (ret) {
264 		pr_err("%s skcipher algorithm registration error (%d)\n",
265 		       alg->base.cra_name, ret);
266 		kfree(ccp_alg);
267 		return ret;
268 	}
269 
270 	list_add(&ccp_alg->entry, head);
271 
272 	return 0;
273 }
274 
275 int ccp_register_aes_xts_algs(struct list_head *head)
276 {
277 	int i, ret;
278 
279 	for (i = 0; i < ARRAY_SIZE(aes_xts_algs); i++) {
280 		ret = ccp_register_aes_xts_alg(head, &aes_xts_algs[i]);
281 		if (ret)
282 			return ret;
283 	}
284 
285 	return 0;
286 }
287