1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 * AEAD: Authenticated Encryption with Associated Data
4 *
5 * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
6 */
7
8 #ifndef _CRYPTO_AEAD_H
9 #define _CRYPTO_AEAD_H
10
11 #include <linux/atomic.h>
12 #include <linux/container_of.h>
13 #include <linux/crypto.h>
14 #include <linux/slab.h>
15 #include <linux/types.h>
16
17 /**
18 * DOC: Authenticated Encryption With Associated Data (AEAD) Cipher API
19 *
20 * The AEAD cipher API is used with the ciphers of type CRYPTO_ALG_TYPE_AEAD
21 * (listed as type "aead" in /proc/crypto)
22 *
23 * The most prominent examples for this type of encryption is GCM and CCM.
24 * However, the kernel supports other types of AEAD ciphers which are defined
25 * with the following cipher string:
26 *
27 * authenc(keyed message digest, block cipher)
28 *
29 * For example: authenc(hmac(sha256), cbc(aes))
30 *
31 * The example code provided for the symmetric key cipher operation applies
32 * here as well. Naturally all *skcipher* symbols must be exchanged the *aead*
33 * pendants discussed in the following. In addition, for the AEAD operation,
34 * the aead_request_set_ad function must be used to set the pointer to the
35 * associated data memory location before performing the encryption or
36 * decryption operation. Another deviation from the asynchronous block cipher
37 * operation is that the caller should explicitly check for -EBADMSG of the
38 * crypto_aead_decrypt. That error indicates an authentication error, i.e.
39 * a breach in the integrity of the message. In essence, that -EBADMSG error
40 * code is the key bonus an AEAD cipher has over "standard" block chaining
41 * modes.
42 *
43 * Memory Structure:
44 *
45 * The source scatterlist must contain the concatenation of
46 * associated data || plaintext or ciphertext.
47 *
48 * The destination scatterlist has the same layout, except that the plaintext
49 * (resp. ciphertext) will grow (resp. shrink) by the authentication tag size
50 * during encryption (resp. decryption). The authentication tag is generated
51 * during the encryption operation and appended to the ciphertext. During
52 * decryption, the authentication tag is consumed along with the ciphertext and
53 * used to verify the integrity of the plaintext and the associated data.
54 *
55 * In-place encryption/decryption is enabled by using the same scatterlist
56 * pointer for both the source and destination.
57 *
58 * Even in the out-of-place case, space must be reserved in the destination for
59 * the associated data, even though it won't be written to. This makes the
60 * in-place and out-of-place cases more consistent. It is permissible for the
61 * "destination" associated data to alias the "source" associated data.
62 *
63 * As with the other scatterlist crypto APIs, zero-length scatterlist elements
64 * are not allowed in the used part of the scatterlist. Thus, if there is no
65 * associated data, the first element must point to the plaintext/ciphertext.
66 *
67 * To meet the needs of IPsec, a special quirk applies to rfc4106, rfc4309,
68 * rfc4543, and rfc7539esp ciphers. For these ciphers, the final 'ivsize' bytes
69 * of the associated data buffer must contain a second copy of the IV. This is
70 * in addition to the copy passed to aead_request_set_crypt(). These two IV
71 * copies must not differ; different implementations of the same algorithm may
72 * behave differently in that case. Note that the algorithm might not actually
73 * treat the IV as associated data; nevertheless the length passed to
74 * aead_request_set_ad() must include it.
75 */
76
77 struct crypto_aead;
78 struct scatterlist;
79
80 /**
81 * struct aead_request - AEAD request
82 * @base: Common attributes for async crypto requests
83 * @assoclen: Length in bytes of associated data for authentication
84 * @cryptlen: Length of data to be encrypted or decrypted
85 * @iv: Initialisation vector
86 * @src: Source data
87 * @dst: Destination data
88 * @__ctx: Start of private context data
89 */
90 struct aead_request {
91 struct crypto_async_request base;
92
93 unsigned int assoclen;
94 unsigned int cryptlen;
95
96 u8 *iv;
97
98 struct scatterlist *src;
99 struct scatterlist *dst;
100
101 void *__ctx[] CRYPTO_MINALIGN_ATTR;
102 };
103
104 /**
105 * struct aead_alg - AEAD cipher definition
106 * @maxauthsize: Set the maximum authentication tag size supported by the
107 * transformation. A transformation may support smaller tag sizes.
108 * As the authentication tag is a message digest to ensure the
109 * integrity of the encrypted data, a consumer typically wants the
110 * largest authentication tag possible as defined by this
111 * variable.
112 * @setauthsize: Set authentication size for the AEAD transformation. This
113 * function is used to specify the consumer requested size of the
114 * authentication tag to be either generated by the transformation
115 * during encryption or the size of the authentication tag to be
116 * supplied during the decryption operation. This function is also
117 * responsible for checking the authentication tag size for
118 * validity.
119 * @setkey: see struct skcipher_alg
120 * @encrypt: see struct skcipher_alg
121 * @decrypt: see struct skcipher_alg
122 * @ivsize: see struct skcipher_alg
123 * @chunksize: see struct skcipher_alg
124 * @init: Initialize the cryptographic transformation object. This function
125 * is used to initialize the cryptographic transformation object.
126 * This function is called only once at the instantiation time, right
127 * after the transformation context was allocated. In case the
128 * cryptographic hardware has some special requirements which need to
129 * be handled by software, this function shall check for the precise
130 * requirement of the transformation and put any software fallbacks
131 * in place.
132 * @exit: Deinitialize the cryptographic transformation object. This is a
133 * counterpart to @init, used to remove various changes set in
134 * @init.
135 * @base: Definition of a generic crypto cipher algorithm.
136 *
137 * All fields except @ivsize is mandatory and must be filled.
138 */
139 struct aead_alg {
140 int (*setkey)(struct crypto_aead *tfm, const u8 *key,
141 unsigned int keylen);
142 int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize);
143 int (*encrypt)(struct aead_request *req);
144 int (*decrypt)(struct aead_request *req);
145 int (*init)(struct crypto_aead *tfm);
146 void (*exit)(struct crypto_aead *tfm);
147
148 unsigned int ivsize;
149 unsigned int maxauthsize;
150 unsigned int chunksize;
151
152 struct crypto_alg base;
153 };
154
155 struct crypto_aead {
156 unsigned int authsize;
157 unsigned int reqsize;
158
159 struct crypto_tfm base;
160 };
161
162 static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
163 {
164 return container_of(tfm, struct crypto_aead, base);
165 }
166
167 /**
168 * crypto_alloc_aead() - allocate AEAD cipher handle
169 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
170 * AEAD cipher
171 * @type: specifies the type of the cipher
172 * @mask: specifies the mask for the cipher
173 *
174 * Allocate a cipher handle for an AEAD. The returned struct
175 * crypto_aead is the cipher handle that is required for any subsequent
176 * API invocation for that AEAD.
177 *
178 * Return: allocated cipher handle in case of success; IS_ERR() is true in case
179 * of an error, PTR_ERR() returns the error code.
180 */
181 struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);
182
183 static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
184 {
185 return &tfm->base;
186 }
187
188 /**
189 * crypto_free_aead() - zeroize and free aead handle
190 * @tfm: cipher handle to be freed
191 *
192 * If @tfm is a NULL or error pointer, this function does nothing.
193 */
194 static inline void crypto_free_aead(struct crypto_aead *tfm)
195 {
196 crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
197 }
198
199 /**
200 * crypto_has_aead() - Search for the availability of an aead.
201 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
202 * aead
203 * @type: specifies the type of the aead
204 * @mask: specifies the mask for the aead
205 *
206 * Return: true when the aead is known to the kernel crypto API; false
207 * otherwise
208 */
209 int crypto_has_aead(const char *alg_name, u32 type, u32 mask);
210
211 static inline const char *crypto_aead_driver_name(struct crypto_aead *tfm)
212 {
213 return crypto_tfm_alg_driver_name(crypto_aead_tfm(tfm));
214 }
215
216 static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
217 {
218 return container_of(crypto_aead_tfm(tfm)->__crt_alg,
219 struct aead_alg, base);
220 }
221
222 static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
223 {
224 return alg->ivsize;
225 }
226
227 /**
228 * crypto_aead_ivsize() - obtain IV size
229 * @tfm: cipher handle
230 *
231 * The size of the IV for the aead referenced by the cipher handle is
232 * returned. This IV size may be zero if the cipher does not need an IV.
233 *
234 * Return: IV size in bytes
235 */
236 static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)
237 {
238 return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
239 }
240
241 /**
242 * crypto_aead_authsize() - obtain maximum authentication data size
243 * @tfm: cipher handle
244 *
245 * The maximum size of the authentication data for the AEAD cipher referenced
246 * by the AEAD cipher handle is returned. The authentication data size may be
247 * zero if the cipher implements a hard-coded maximum.
248 *
249 * The authentication data may also be known as "tag value".
250 *
251 * Return: authentication data size / tag size in bytes
252 */
253 static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)
254 {
255 return tfm->authsize;
256 }
257
258 static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg)
259 {
260 return alg->maxauthsize;
261 }
262
263 static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead)
264 {
265 return crypto_aead_alg_maxauthsize(crypto_aead_alg(aead));
266 }
267
268 /**
269 * crypto_aead_blocksize() - obtain block size of cipher
270 * @tfm: cipher handle
271 *
272 * The block size for the AEAD referenced with the cipher handle is returned.
273 * The caller may use that information to allocate appropriate memory for the
274 * data returned by the encryption or decryption operation
275 *
276 * Return: block size of cipher
277 */
278 static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
279 {
280 return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
281 }
282
283 static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
284 {
285 return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));
286 }
287
288 static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)
289 {
290 return crypto_tfm_get_flags(crypto_aead_tfm(tfm));
291 }
292
293 static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)
294 {
295 crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);
296 }
297
298 static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)
299 {
300 crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
301 }
302
303 /**
304 * crypto_aead_setkey() - set key for cipher
305 * @tfm: cipher handle
306 * @key: buffer holding the key
307 * @keylen: length of the key in bytes
308 *
309 * The caller provided key is set for the AEAD referenced by the cipher
310 * handle.
311 *
312 * Note, the key length determines the cipher type. Many block ciphers implement
313 * different cipher modes depending on the key size, such as AES-128 vs AES-192
314 * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
315 * is performed.
316 *
317 * Return: 0 if the setting of the key was successful; < 0 if an error occurred
318 */
319 int crypto_aead_setkey(struct crypto_aead *tfm,
320 const u8 *key, unsigned int keylen);
321
322 /**
323 * crypto_aead_setauthsize() - set authentication data size
324 * @tfm: cipher handle
325 * @authsize: size of the authentication data / tag in bytes
326 *
327 * Set the authentication data size / tag size. AEAD requires an authentication
328 * tag (or MAC) in addition to the associated data.
329 *
330 * Return: 0 if the setting of the key was successful; < 0 if an error occurred
331 */
332 int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);
333
334 static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
335 {
336 return __crypto_aead_cast(req->base.tfm);
337 }
338
339 /**
340 * crypto_aead_encrypt() - encrypt plaintext
341 * @req: reference to the aead_request handle that holds all information
342 * needed to perform the cipher operation
343 *
344 * Encrypt plaintext data using the aead_request handle. That data structure
345 * and how it is filled with data is discussed with the aead_request_*
346 * functions.
347 *
348 * IMPORTANT NOTE The encryption operation creates the authentication data /
349 * tag. That data is concatenated with the created ciphertext.
350 * The ciphertext memory size is therefore the given number of
351 * block cipher blocks + the size defined by the
352 * crypto_aead_setauthsize invocation. The caller must ensure
353 * that sufficient memory is available for the ciphertext and
354 * the authentication tag.
355 *
356 * Return: 0 if the cipher operation was successful; < 0 if an error occurred
357 */
358 int crypto_aead_encrypt(struct aead_request *req);
359
360 /**
361 * crypto_aead_decrypt() - decrypt ciphertext
362 * @req: reference to the aead_request handle that holds all information
363 * needed to perform the cipher operation
364 *
365 * Decrypt ciphertext data using the aead_request handle. That data structure
366 * and how it is filled with data is discussed with the aead_request_*
367 * functions.
368 *
369 * IMPORTANT NOTE The caller must concatenate the ciphertext followed by the
370 * authentication data / tag. That authentication data / tag
371 * must have the size defined by the crypto_aead_setauthsize
372 * invocation.
373 *
374 *
375 * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
376 * cipher operation performs the authentication of the data during the
377 * decryption operation. Therefore, the function returns this error if
378 * the authentication of the ciphertext was unsuccessful (i.e. the
379 * integrity of the ciphertext or the associated data was violated);
380 * < 0 if an error occurred.
381 */
382 int crypto_aead_decrypt(struct aead_request *req);
383
384 /**
385 * DOC: Asynchronous AEAD Request Handle
386 *
387 * The aead_request data structure contains all pointers to data required for
388 * the AEAD cipher operation. This includes the cipher handle (which can be
389 * used by multiple aead_request instances), pointer to plaintext and
390 * ciphertext, asynchronous callback function, etc. It acts as a handle to the
391 * aead_request_* API calls in a similar way as AEAD handle to the
392 * crypto_aead_* API calls.
393 */
394
395 /**
396 * crypto_aead_reqsize() - obtain size of the request data structure
397 * @tfm: cipher handle
398 *
399 * Return: number of bytes
400 */
401 static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)
402 {
403 return tfm->reqsize;
404 }
405
406 /**
407 * aead_request_set_tfm() - update cipher handle reference in request
408 * @req: request handle to be modified
409 * @tfm: cipher handle that shall be added to the request handle
410 *
411 * Allow the caller to replace the existing aead handle in the request
412 * data structure with a different one.
413 */
414 static inline void aead_request_set_tfm(struct aead_request *req,
415 struct crypto_aead *tfm)
416 {
417 req->base.tfm = crypto_aead_tfm(tfm);
418 }
419
420 /**
421 * aead_request_alloc() - allocate request data structure
422 * @tfm: cipher handle to be registered with the request
423 * @gfp: memory allocation flag that is handed to kmalloc by the API call.
424 *
425 * Allocate the request data structure that must be used with the AEAD
426 * encrypt and decrypt API calls. During the allocation, the provided aead
427 * handle is registered in the request data structure.
428 *
429 * Return: allocated request handle in case of success, or NULL if out of memory
430 */
431 static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
432 gfp_t gfp)
433 {
434 struct aead_request *req;
435
436 req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);
437
438 if (likely(req))
439 aead_request_set_tfm(req, tfm);
440
441 return req;
442 }
443
444 /**
445 * aead_request_free() - zeroize and free request data structure
446 * @req: request data structure cipher handle to be freed
447 */
448 static inline void aead_request_free(struct aead_request *req)
449 {
450 kfree_sensitive(req);
451 }
452
453 /**
454 * aead_request_set_callback() - set asynchronous callback function
455 * @req: request handle
456 * @flags: specify zero or an ORing of the flags
457 * CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
458 * increase the wait queue beyond the initial maximum size;
459 * CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
460 * @compl: callback function pointer to be registered with the request handle
461 * @data: The data pointer refers to memory that is not used by the kernel
462 * crypto API, but provided to the callback function for it to use. Here,
463 * the caller can provide a reference to memory the callback function can
464 * operate on. As the callback function is invoked asynchronously to the
465 * related functionality, it may need to access data structures of the
466 * related functionality which can be referenced using this pointer. The
467 * callback function can access the memory via the "data" field in the
468 * crypto_async_request data structure provided to the callback function.
469 *
470 * Setting the callback function that is triggered once the cipher operation
471 * completes
472 *
473 * The callback function is registered with the aead_request handle and
474 * must comply with the following template::
475 *
476 * void callback_function(struct crypto_async_request *req, int error)
477 */
478 static inline void aead_request_set_callback(struct aead_request *req,
479 u32 flags,
480 crypto_completion_t compl,
481 void *data)
482 {
483 req->base.complete = compl;
484 req->base.data = data;
485 req->base.flags = flags;
486 }
487
488 /**
489 * aead_request_set_crypt - set data buffers
490 * @req: request handle
491 * @src: source scatter / gather list
492 * @dst: destination scatter / gather list
493 * @cryptlen: number of bytes to process from @src
494 * @iv: IV for the cipher operation which must comply with the IV size defined
495 * by crypto_aead_ivsize()
496 *
497 * Setting the source data and destination data scatter / gather lists which
498 * hold the associated data concatenated with the plaintext or ciphertext. See
499 * below for the authentication tag.
500 *
501 * For encryption, the source is treated as the plaintext and the
502 * destination is the ciphertext. For a decryption operation, the use is
503 * reversed - the source is the ciphertext and the destination is the plaintext.
504 *
505 * The memory structure for cipher operation has the following structure:
506 *
507 * - AEAD encryption input: assoc data || plaintext
508 * - AEAD encryption output: assoc data || ciphertext || auth tag
509 * - AEAD decryption input: assoc data || ciphertext || auth tag
510 * - AEAD decryption output: assoc data || plaintext
511 *
512 * Albeit the kernel requires the presence of the AAD buffer, however,
513 * the kernel does not fill the AAD buffer in the output case. If the
514 * caller wants to have that data buffer filled, the caller must either
515 * use an in-place cipher operation (i.e. same memory location for
516 * input/output memory location).
517 */
518 static inline void aead_request_set_crypt(struct aead_request *req,
519 struct scatterlist *src,
520 struct scatterlist *dst,
521 unsigned int cryptlen, u8 *iv)
522 {
523 req->src = src;
524 req->dst = dst;
525 req->cryptlen = cryptlen;
526 req->iv = iv;
527 }
528
529 /**
530 * aead_request_set_ad - set associated data information
531 * @req: request handle
532 * @assoclen: number of bytes in associated data
533 *
534 * Setting the AD information. This function sets the length of
535 * the associated data.
536 */
537 static inline void aead_request_set_ad(struct aead_request *req,
538 unsigned int assoclen)
539 {
540 req->assoclen = assoclen;
541 }
542
543 #endif /* _CRYPTO_AEAD_H */
544
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