aboutsummaryrefslogtreecommitdiff
path: root/include/crypto/aead.h
blob: e728469c4cccb3aa56835b042ee83373377acf24 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * AEAD: Authenticated Encryption with Associated Data
 * 
 * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
 */

#ifndef _CRYPTO_AEAD_H
#define _CRYPTO_AEAD_H

#include <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/slab.h>

/**
 * DOC: Authenticated Encryption With Associated Data (AEAD) Cipher API
 *
 * The AEAD cipher API is used with the ciphers of type CRYPTO_ALG_TYPE_AEAD
 * (listed as type "aead" in /proc/crypto)
 *
 * The most prominent examples for this type of encryption is GCM and CCM.
 * However, the kernel supports other types of AEAD ciphers which are defined
 * with the following cipher string:
 *
 *	authenc(keyed message digest, block cipher)
 *
 * For example: authenc(hmac(sha256), cbc(aes))
 *
 * The example code provided for the symmetric key cipher operation
 * applies here as well. Naturally all *skcipher* symbols must be exchanged
 * the *aead* pendants discussed in the following. In addition, for the AEAD
 * operation, the aead_request_set_ad function must be used to set the
 * pointer to the associated data memory location before performing the
 * encryption or decryption operation. In case of an encryption, the associated
 * data memory is filled during the encryption operation. For decryption, the
 * associated data memory must contain data that is used to verify the integrity
 * of the decrypted data. Another deviation from the asynchronous block cipher
 * operation is that the caller should explicitly check for -EBADMSG of the
 * crypto_aead_decrypt. That error indicates an authentication error, i.e.
 * a breach in the integrity of the message. In essence, that -EBADMSG error
 * code is the key bonus an AEAD cipher has over "standard" block chaining
 * modes.
 *
 * Memory Structure:
 *
 * The source scatterlist must contain the concatenation of
 * associated data || plaintext or ciphertext.
 *
 * The destination scatterlist has the same layout, except that the plaintext
 * (resp. ciphertext) will grow (resp. shrink) by the authentication tag size
 * during encryption (resp. decryption).
 *
 * In-place encryption/decryption is enabled by using the same scatterlist
 * pointer for both the source and destination.
 *
 * Even in the out-of-place case, space must be reserved in the destination for
 * the associated data, even though it won't be written to.  This makes the
 * in-place and out-of-place cases more consistent.  It is permissible for the
 * "destination" associated data to alias the "source" associated data.
 *
 * As with the other scatterlist crypto APIs, zero-length scatterlist elements
 * are not allowed in the used part of the scatterlist.  Thus, if there is no
 * associated data, the first element must point to the plaintext/ciphertext.
 *
 * To meet the needs of IPsec, a special quirk applies to rfc4106, rfc4309,
 * rfc4543, and rfc7539esp ciphers.  For these ciphers, the final 'ivsize' bytes
 * of the associated data buffer must contain a second copy of the IV.  This is
 * in addition to the copy passed to aead_request_set_crypt().  These two IV
 * copies must not differ; different implementations of the same algorithm may
 * behave differently in that case.  Note that the algorithm might not actually
 * treat the IV as associated data; nevertheless the length passed to
 * aead_request_set_ad() must include it.
 */

struct crypto_aead;

/**
 *	struct aead_request - AEAD request
 *	@base: Common attributes for async crypto requests
 *	@assoclen: Length in bytes of associated data for authentication
 *	@cryptlen: Length of data to be encrypted or decrypted
 *	@iv: Initialisation vector
 *	@src: Source data
 *	@dst: Destination data
 *	@__ctx: Start of private context data
 */
struct aead_request {
	struct crypto_async_request base;

	unsigned int assoclen;
	unsigned int cryptlen;

	u8 *iv;

	struct scatterlist *src;
	struct scatterlist *dst;

	void *__ctx[] CRYPTO_MINALIGN_ATTR;
};

/**
 * struct aead_alg - AEAD cipher definition
 * @maxauthsize: Set the maximum authentication tag size supported by the
 *		 transformation. A transformation may support smaller tag sizes.
 *		 As the authentication tag is a message digest to ensure the
 *		 integrity of the encrypted data, a consumer typically wants the
 *		 largest authentication tag possible as defined by this
 *		 variable.
 * @setauthsize: Set authentication size for the AEAD transformation. This
 *		 function is used to specify the consumer requested size of the
 * 		 authentication tag to be either generated by the transformation
 *		 during encryption or the size of the authentication tag to be
 *		 supplied during the decryption operation. This function is also
 *		 responsible for checking the authentication tag size for
 *		 validity.
 * @setkey: see struct skcipher_alg
 * @encrypt: see struct skcipher_alg
 * @decrypt: see struct skcipher_alg
 * @ivsize: see struct skcipher_alg
 * @chunksize: see struct skcipher_alg
 * @init: Initialize the cryptographic transformation object. This function
 *	  is used to initialize the cryptographic transformation object.
 *	  This function is called only once at the instantiation time, right
 *	  after the transformation context was allocated. In case the
 *	  cryptographic hardware has some special requirements which need to
 *	  be handled by software, this function shall check for the precise
 *	  requirement of the transformation and put any software fallbacks
 *	  in place.
 * @exit: Deinitialize the cryptographic transformation object. This is a
 *	  counterpart to @init, used to remove various changes set in
 *	  @init.
 * @base: Definition of a generic crypto cipher algorithm.
 *
 * All fields except @ivsize is mandatory and must be filled.
 */
struct aead_alg {
	int (*setkey)(struct crypto_aead *tfm, const u8 *key,
	              unsigned int keylen);
	int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize);
	int (*encrypt)(struct aead_request *req);
	int (*decrypt)(struct aead_request *req);
	int (*init)(struct crypto_aead *tfm);
	void (*exit)(struct crypto_aead *tfm);

	unsigned int ivsize;
	unsigned int maxauthsize;
	unsigned int chunksize;

	struct crypto_alg base;
};

struct crypto_aead {
	unsigned int authsize;
	unsigned int reqsize;

	struct crypto_tfm base;
};

static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
{
	return container_of(tfm, struct crypto_aead, base);
}

/**
 * crypto_alloc_aead() - allocate AEAD cipher handle
 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
 *	     AEAD cipher
 * @type: specifies the type of the cipher
 * @mask: specifies the mask for the cipher
 *
 * Allocate a cipher handle for an AEAD. The returned struct
 * crypto_aead is the cipher handle that is required for any subsequent
 * API invocation for that AEAD.
 *
 * Return: allocated cipher handle in case of success; IS_ERR() is true in case
 *	   of an error, PTR_ERR() returns the error code.
 */
struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);

static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
{
	return &tfm->base;
}

/**
 * crypto_free_aead() - zeroize and free aead handle
 * @tfm: cipher handle to be freed
 *
 * If @tfm is a NULL or error pointer, this function does nothing.
 */
static inline void crypto_free_aead(struct crypto_aead *tfm)
{
	crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
}

static inline const char *crypto_aead_driver_name(struct crypto_aead *tfm)
{
	return crypto_tfm_alg_driver_name(crypto_aead_tfm(tfm));
}

static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
{
	return container_of(crypto_aead_tfm(tfm)->__crt_alg,
			    struct aead_alg, base);
}

static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
{
	return alg->ivsize;
}

/**
 * crypto_aead_ivsize() - obtain IV size
 * @tfm: cipher handle
 *
 * The size of the IV for the aead referenced by the cipher handle is
 * returned. This IV size may be zero if the cipher does not need an IV.
 *
 * Return: IV size in bytes
 */
static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)
{
	return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
}

/**
 * crypto_aead_authsize() - obtain maximum authentication data size
 * @tfm: cipher handle
 *
 * The maximum size of the authentication data for the AEAD cipher referenced
 * by the AEAD cipher handle is returned. The authentication data size may be
 * zero if the cipher implements a hard-coded maximum.
 *
 * The authentication data may also be known as "tag value".
 *
 * Return: authentication data size / tag size in bytes
 */
static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)
{
	return tfm->authsize;
}

static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg)
{
	return alg->maxauthsize;
}

static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead)
{
	return crypto_aead_alg_maxauthsize(crypto_aead_alg(aead));
}

/**
 * crypto_aead_blocksize() - obtain block size of cipher
 * @tfm: cipher handle
 *
 * The block size for the AEAD referenced with the cipher handle is returned.
 * The caller may use that information to allocate appropriate memory for the
 * data returned by the encryption or decryption operation
 *
 * Return: block size of cipher
 */
static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
{
	return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
}

static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
{
	return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));
}

static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)
{
	return crypto_tfm_get_flags(crypto_aead_tfm(tfm));
}

static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)
{
	crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);
}

static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)
{
	crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
}

/**
 * crypto_aead_setkey() - set key for cipher
 * @tfm: cipher handle
 * @key: buffer holding the key
 * @keylen: length of the key in bytes
 *
 * The caller provided key is set for the AEAD referenced by the cipher
 * handle.
 *
 * Note, the key length determines the cipher type. Many block ciphers implement
 * different cipher modes depending on the key size, such as AES-128 vs AES-192
 * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
 * is performed.
 *
 * Return: 0 if the setting of the key was successful; < 0 if an error occurred
 */
int crypto_aead_setkey(struct crypto_aead *tfm,
		       const u8 *key, unsigned int keylen);

/**
 * crypto_aead_setauthsize() - set authentication data size
 * @tfm: cipher handle
 * @authsize: size of the authentication data / tag in bytes
 *
 * Set the authentication data size / tag size. AEAD requires an authentication
 * tag (or MAC) in addition to the associated data.
 *
 * Return: 0 if the setting of the key was successful; < 0 if an error occurred
 */
int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);

static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
{
	return __crypto_aead_cast(req->base.tfm);
}

/**
 * crypto_aead_encrypt() - encrypt plaintext
 * @req: reference to the aead_request handle that holds all information
 *	 needed to perform the cipher operation
 *
 * Encrypt plaintext data using the aead_request handle. That data structure
 * and how it is filled with data is discussed with the aead_request_*
 * functions.
 *
 * IMPORTANT NOTE The encryption operation creates the authentication data /
 *		  tag. That data is concatenated with the created ciphertext.
 *		  The ciphertext memory size is therefore the given number of
 *		  block cipher blocks + the size defined by the
 *		  crypto_aead_setauthsize invocation. The caller must ensure
 *		  that sufficient memory is available for the ciphertext and
 *		  the authentication tag.
 *
 * Return: 0 if the cipher operation was successful; < 0 if an error occurred
 */
int crypto_aead_encrypt(struct aead_request *req);

/**
 * crypto_aead_decrypt() - decrypt ciphertext
 * @req: reference to the aead_request handle that holds all information
 *	 needed to perform the cipher operation
 *
 * Decrypt ciphertext data using the aead_request handle. That data structure
 * and how it is filled with data is discussed with the aead_request_*
 * functions.
 *
 * IMPORTANT NOTE The caller must concatenate the ciphertext followed by the
 *		  authentication data / tag. That authentication data / tag
 *		  must have the size defined by the crypto_aead_setauthsize
 *		  invocation.
 *
 *
 * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
 *	   cipher operation performs the authentication of the data during the
 *	   decryption operation. Therefore, the function returns this error if
 *	   the authentication of the ciphertext was unsuccessful (i.e. the
 *	   integrity of the ciphertext or the associated data was violated);
 *	   < 0 if an error occurred.
 */
int crypto_aead_decrypt(struct aead_request *req);

/**
 * DOC: Asynchronous AEAD Request Handle
 *
 * The aead_request data structure contains all pointers to data required for
 * the AEAD cipher operation. This includes the cipher handle (which can be
 * used by multiple aead_request instances), pointer to plaintext and
 * ciphertext, asynchronous callback function, etc. It acts as a handle to the
 * aead_request_* API calls in a similar way as AEAD handle to the
 * crypto_aead_* API calls.
 */

/**
 * crypto_aead_reqsize() - obtain size of the request data structure
 * @tfm: cipher handle
 *
 * Return: number of bytes
 */
static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)
{
	return tfm->reqsize;
}

/**
 * aead_request_set_tfm() - update cipher handle reference in request
 * @req: request handle to be modified
 * @tfm: cipher handle that shall be added to the request handle
 *
 * Allow the caller to replace the existing aead handle in the request
 * data structure with a different one.
 */
static inline void aead_request_set_tfm(struct aead_request *req,
					struct crypto_aead *tfm)
{
	req->base.tfm = crypto_aead_tfm(tfm);
}

/**
 * aead_request_alloc() - allocate request data structure
 * @tfm: cipher handle to be registered with the request
 * @gfp: memory allocation flag that is handed to kmalloc by the API call.
 *
 * Allocate the request data structure that must be used with the AEAD
 * encrypt and decrypt API calls. During the allocation, the provided aead
 * handle is registered in the request data structure.
 *
 * Return: allocated request handle in case of success, or NULL if out of memory
 */
static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
						      gfp_t gfp)
{
	struct aead_request *req;

	req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);

	if (likely(req))
		aead_request_set_tfm(req, tfm);

	return req;
}

/**
 * aead_request_free() - zeroize and free request data structure
 * @req: request data structure cipher handle to be freed
 */
static inline void aead_request_free(struct aead_request *req)
{
	kfree_sensitive(req);
}

/**
 * aead_request_set_callback() - set asynchronous callback function
 * @req: request handle
 * @flags: specify zero or an ORing of the flags
 *	   CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
 *	   increase the wait queue beyond the initial maximum size;
 *	   CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
 * @compl: callback function pointer to be registered with the request handle
 * @data: The data pointer refers to memory that is not used by the kernel
 *	  crypto API, but provided to the callback function for it to use. Here,
 *	  the caller can provide a reference to memory the callback function can
 *	  operate on. As the callback function is invoked asynchronously to the
 *	  related functionality, it may need to access data structures of the
 *	  related functionality which can be referenced using this pointer. The
 *	  callback function can access the memory via the "data" field in the
 *	  crypto_async_request data structure provided to the callback function.
 *
 * Setting the callback function that is triggered once the cipher operation
 * completes
 *
 * The callback function is registered with the aead_request handle and
 * must comply with the following template::
 *
 *	void callback_function(struct crypto_async_request *req, int error)
 */
static inline void aead_request_set_callback(struct aead_request *req,
					     u32 flags,
					     crypto_completion_t compl,
					     void *data)
{
	req->base.complete = compl;
	req->base.data = data;
	req->base.flags = flags;
}

/**
 * aead_request_set_crypt - set data buffers
 * @req: request handle
 * @src: source scatter / gather list
 * @dst: destination scatter / gather list
 * @cryptlen: number of bytes to process from @src
 * @iv: IV for the cipher operation which must comply with the IV size defined
 *      by crypto_aead_ivsize()
 *
 * Setting the source data and destination data scatter / gather lists which
 * hold the associated data concatenated with the plaintext or ciphertext. See
 * below for the authentication tag.
 *
 * For encryption, the source is treated as the plaintext and the
 * destination is the ciphertext. For a decryption operation, the use is
 * reversed - the source is the ciphertext and the destination is the plaintext.
 *
 * The memory structure for cipher operation has the following structure:
 *
 * - AEAD encryption input:  assoc data || plaintext
 * - AEAD encryption output: assoc data || cipherntext || auth tag
 * - AEAD decryption input:  assoc data || ciphertext || auth tag
 * - AEAD decryption output: assoc data || plaintext
 *
 * Albeit the kernel requires the presence of the AAD buffer, however,
 * the kernel does not fill the AAD buffer in the output case. If the
 * caller wants to have that data buffer filled, the caller must either
 * use an in-place cipher operation (i.e. same memory location for
 * input/output memory location).
 */
static inline void aead_request_set_crypt(struct aead_request *req,
					  struct scatterlist *src,
					  struct scatterlist *dst,
					  unsigned int cryptlen, u8 *iv)
{
	req->src = src;
	req->dst = dst;
	req->cryptlen = cryptlen;
	req->iv = iv;
}

/**
 * aead_request_set_ad - set associated data information
 * @req: request handle
 * @assoclen: number of bytes in associated data
 *
 * Setting the AD information.  This function sets the length of
 * the associated data.
 */
static inline void aead_request_set_ad(struct aead_request *req,
				       unsigned int assoclen)
{
	req->assoclen = assoclen;
}

#endif	/* _CRYPTO_AEAD_H */