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 crypto_istat_aead - statistics for AEAD algorithm |
106 | * @encrypt_cnt: number of encrypt requests |
107 | * @encrypt_tlen: total data size handled by encrypt requests |
108 | * @decrypt_cnt: number of decrypt requests |
109 | * @decrypt_tlen: total data size handled by decrypt requests |
110 | * @err_cnt: number of error for AEAD requests |
111 | */ |
112 | struct crypto_istat_aead { |
113 | atomic64_t encrypt_cnt; |
114 | atomic64_t encrypt_tlen; |
115 | atomic64_t decrypt_cnt; |
116 | atomic64_t decrypt_tlen; |
117 | atomic64_t err_cnt; |
118 | }; |
119 | |
120 | /** |
121 | * struct aead_alg - AEAD cipher definition |
122 | * @maxauthsize: Set the maximum authentication tag size supported by the |
123 | * transformation. A transformation may support smaller tag sizes. |
124 | * As the authentication tag is a message digest to ensure the |
125 | * integrity of the encrypted data, a consumer typically wants the |
126 | * largest authentication tag possible as defined by this |
127 | * variable. |
128 | * @setauthsize: Set authentication size for the AEAD transformation. This |
129 | * function is used to specify the consumer requested size of the |
130 | * authentication tag to be either generated by the transformation |
131 | * during encryption or the size of the authentication tag to be |
132 | * supplied during the decryption operation. This function is also |
133 | * responsible for checking the authentication tag size for |
134 | * validity. |
135 | * @setkey: see struct skcipher_alg |
136 | * @encrypt: see struct skcipher_alg |
137 | * @decrypt: see struct skcipher_alg |
138 | * @stat: statistics for AEAD algorithm |
139 | * @ivsize: see struct skcipher_alg |
140 | * @chunksize: see struct skcipher_alg |
141 | * @init: Initialize the cryptographic transformation object. This function |
142 | * is used to initialize the cryptographic transformation object. |
143 | * This function is called only once at the instantiation time, right |
144 | * after the transformation context was allocated. In case the |
145 | * cryptographic hardware has some special requirements which need to |
146 | * be handled by software, this function shall check for the precise |
147 | * requirement of the transformation and put any software fallbacks |
148 | * in place. |
149 | * @exit: Deinitialize the cryptographic transformation object. This is a |
150 | * counterpart to @init, used to remove various changes set in |
151 | * @init. |
152 | * @base: Definition of a generic crypto cipher algorithm. |
153 | * |
154 | * All fields except @ivsize is mandatory and must be filled. |
155 | */ |
156 | struct aead_alg { |
157 | int (*setkey)(struct crypto_aead *tfm, const u8 *key, |
158 | unsigned int keylen); |
159 | int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize); |
160 | int (*encrypt)(struct aead_request *req); |
161 | int (*decrypt)(struct aead_request *req); |
162 | int (*init)(struct crypto_aead *tfm); |
163 | void (*exit)(struct crypto_aead *tfm); |
164 | |
165 | #ifdef CONFIG_CRYPTO_STATS |
166 | struct crypto_istat_aead stat; |
167 | #endif |
168 | |
169 | unsigned int ivsize; |
170 | unsigned int maxauthsize; |
171 | unsigned int chunksize; |
172 | |
173 | struct crypto_alg base; |
174 | }; |
175 | |
176 | struct crypto_aead { |
177 | unsigned int authsize; |
178 | unsigned int reqsize; |
179 | |
180 | struct crypto_tfm base; |
181 | }; |
182 | |
183 | static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm) |
184 | { |
185 | return container_of(tfm, struct crypto_aead, base); |
186 | } |
187 | |
188 | /** |
189 | * crypto_alloc_aead() - allocate AEAD cipher handle |
190 | * @alg_name: is the cra_name / name or cra_driver_name / driver name of the |
191 | * AEAD cipher |
192 | * @type: specifies the type of the cipher |
193 | * @mask: specifies the mask for the cipher |
194 | * |
195 | * Allocate a cipher handle for an AEAD. The returned struct |
196 | * crypto_aead is the cipher handle that is required for any subsequent |
197 | * API invocation for that AEAD. |
198 | * |
199 | * Return: allocated cipher handle in case of success; IS_ERR() is true in case |
200 | * of an error, PTR_ERR() returns the error code. |
201 | */ |
202 | struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask); |
203 | |
204 | static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm) |
205 | { |
206 | return &tfm->base; |
207 | } |
208 | |
209 | /** |
210 | * crypto_free_aead() - zeroize and free aead handle |
211 | * @tfm: cipher handle to be freed |
212 | * |
213 | * If @tfm is a NULL or error pointer, this function does nothing. |
214 | */ |
215 | static inline void crypto_free_aead(struct crypto_aead *tfm) |
216 | { |
217 | crypto_destroy_tfm(mem: tfm, tfm: crypto_aead_tfm(tfm)); |
218 | } |
219 | |
220 | /** |
221 | * crypto_has_aead() - Search for the availability of an aead. |
222 | * @alg_name: is the cra_name / name or cra_driver_name / driver name of the |
223 | * aead |
224 | * @type: specifies the type of the aead |
225 | * @mask: specifies the mask for the aead |
226 | * |
227 | * Return: true when the aead is known to the kernel crypto API; false |
228 | * otherwise |
229 | */ |
230 | int crypto_has_aead(const char *alg_name, u32 type, u32 mask); |
231 | |
232 | static inline const char *crypto_aead_driver_name(struct crypto_aead *tfm) |
233 | { |
234 | return crypto_tfm_alg_driver_name(tfm: crypto_aead_tfm(tfm)); |
235 | } |
236 | |
237 | static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm) |
238 | { |
239 | return container_of(crypto_aead_tfm(tfm)->__crt_alg, |
240 | struct aead_alg, base); |
241 | } |
242 | |
243 | static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg) |
244 | { |
245 | return alg->ivsize; |
246 | } |
247 | |
248 | /** |
249 | * crypto_aead_ivsize() - obtain IV size |
250 | * @tfm: cipher handle |
251 | * |
252 | * The size of the IV for the aead referenced by the cipher handle is |
253 | * returned. This IV size may be zero if the cipher does not need an IV. |
254 | * |
255 | * Return: IV size in bytes |
256 | */ |
257 | static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm) |
258 | { |
259 | return crypto_aead_alg_ivsize(alg: crypto_aead_alg(tfm)); |
260 | } |
261 | |
262 | /** |
263 | * crypto_aead_authsize() - obtain maximum authentication data size |
264 | * @tfm: cipher handle |
265 | * |
266 | * The maximum size of the authentication data for the AEAD cipher referenced |
267 | * by the AEAD cipher handle is returned. The authentication data size may be |
268 | * zero if the cipher implements a hard-coded maximum. |
269 | * |
270 | * The authentication data may also be known as "tag value". |
271 | * |
272 | * Return: authentication data size / tag size in bytes |
273 | */ |
274 | static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm) |
275 | { |
276 | return tfm->authsize; |
277 | } |
278 | |
279 | static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg) |
280 | { |
281 | return alg->maxauthsize; |
282 | } |
283 | |
284 | static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead) |
285 | { |
286 | return crypto_aead_alg_maxauthsize(alg: crypto_aead_alg(tfm: aead)); |
287 | } |
288 | |
289 | /** |
290 | * crypto_aead_blocksize() - obtain block size of cipher |
291 | * @tfm: cipher handle |
292 | * |
293 | * The block size for the AEAD referenced with the cipher handle is returned. |
294 | * The caller may use that information to allocate appropriate memory for the |
295 | * data returned by the encryption or decryption operation |
296 | * |
297 | * Return: block size of cipher |
298 | */ |
299 | static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm) |
300 | { |
301 | return crypto_tfm_alg_blocksize(tfm: crypto_aead_tfm(tfm)); |
302 | } |
303 | |
304 | static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm) |
305 | { |
306 | return crypto_tfm_alg_alignmask(tfm: crypto_aead_tfm(tfm)); |
307 | } |
308 | |
309 | static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm) |
310 | { |
311 | return crypto_tfm_get_flags(tfm: crypto_aead_tfm(tfm)); |
312 | } |
313 | |
314 | static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags) |
315 | { |
316 | crypto_tfm_set_flags(tfm: crypto_aead_tfm(tfm), flags); |
317 | } |
318 | |
319 | static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags) |
320 | { |
321 | crypto_tfm_clear_flags(tfm: crypto_aead_tfm(tfm), flags); |
322 | } |
323 | |
324 | /** |
325 | * crypto_aead_setkey() - set key for cipher |
326 | * @tfm: cipher handle |
327 | * @key: buffer holding the key |
328 | * @keylen: length of the key in bytes |
329 | * |
330 | * The caller provided key is set for the AEAD referenced by the cipher |
331 | * handle. |
332 | * |
333 | * Note, the key length determines the cipher type. Many block ciphers implement |
334 | * different cipher modes depending on the key size, such as AES-128 vs AES-192 |
335 | * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128 |
336 | * is performed. |
337 | * |
338 | * Return: 0 if the setting of the key was successful; < 0 if an error occurred |
339 | */ |
340 | int crypto_aead_setkey(struct crypto_aead *tfm, |
341 | const u8 *key, unsigned int keylen); |
342 | |
343 | /** |
344 | * crypto_aead_setauthsize() - set authentication data size |
345 | * @tfm: cipher handle |
346 | * @authsize: size of the authentication data / tag in bytes |
347 | * |
348 | * Set the authentication data size / tag size. AEAD requires an authentication |
349 | * tag (or MAC) in addition to the associated data. |
350 | * |
351 | * Return: 0 if the setting of the key was successful; < 0 if an error occurred |
352 | */ |
353 | int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize); |
354 | |
355 | static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req) |
356 | { |
357 | return __crypto_aead_cast(tfm: req->base.tfm); |
358 | } |
359 | |
360 | /** |
361 | * crypto_aead_encrypt() - encrypt plaintext |
362 | * @req: reference to the aead_request handle that holds all information |
363 | * needed to perform the cipher operation |
364 | * |
365 | * Encrypt plaintext 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 encryption operation creates the authentication data / |
370 | * tag. That data is concatenated with the created ciphertext. |
371 | * The ciphertext memory size is therefore the given number of |
372 | * block cipher blocks + the size defined by the |
373 | * crypto_aead_setauthsize invocation. The caller must ensure |
374 | * that sufficient memory is available for the ciphertext and |
375 | * the authentication tag. |
376 | * |
377 | * Return: 0 if the cipher operation was successful; < 0 if an error occurred |
378 | */ |
379 | int crypto_aead_encrypt(struct aead_request *req); |
380 | |
381 | /** |
382 | * crypto_aead_decrypt() - decrypt ciphertext |
383 | * @req: reference to the aead_request handle that holds all information |
384 | * needed to perform the cipher operation |
385 | * |
386 | * Decrypt ciphertext data using the aead_request handle. That data structure |
387 | * and how it is filled with data is discussed with the aead_request_* |
388 | * functions. |
389 | * |
390 | * IMPORTANT NOTE The caller must concatenate the ciphertext followed by the |
391 | * authentication data / tag. That authentication data / tag |
392 | * must have the size defined by the crypto_aead_setauthsize |
393 | * invocation. |
394 | * |
395 | * |
396 | * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD |
397 | * cipher operation performs the authentication of the data during the |
398 | * decryption operation. Therefore, the function returns this error if |
399 | * the authentication of the ciphertext was unsuccessful (i.e. the |
400 | * integrity of the ciphertext or the associated data was violated); |
401 | * < 0 if an error occurred. |
402 | */ |
403 | int crypto_aead_decrypt(struct aead_request *req); |
404 | |
405 | /** |
406 | * DOC: Asynchronous AEAD Request Handle |
407 | * |
408 | * The aead_request data structure contains all pointers to data required for |
409 | * the AEAD cipher operation. This includes the cipher handle (which can be |
410 | * used by multiple aead_request instances), pointer to plaintext and |
411 | * ciphertext, asynchronous callback function, etc. It acts as a handle to the |
412 | * aead_request_* API calls in a similar way as AEAD handle to the |
413 | * crypto_aead_* API calls. |
414 | */ |
415 | |
416 | /** |
417 | * crypto_aead_reqsize() - obtain size of the request data structure |
418 | * @tfm: cipher handle |
419 | * |
420 | * Return: number of bytes |
421 | */ |
422 | static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm) |
423 | { |
424 | return tfm->reqsize; |
425 | } |
426 | |
427 | /** |
428 | * aead_request_set_tfm() - update cipher handle reference in request |
429 | * @req: request handle to be modified |
430 | * @tfm: cipher handle that shall be added to the request handle |
431 | * |
432 | * Allow the caller to replace the existing aead handle in the request |
433 | * data structure with a different one. |
434 | */ |
435 | static inline void aead_request_set_tfm(struct aead_request *req, |
436 | struct crypto_aead *tfm) |
437 | { |
438 | req->base.tfm = crypto_aead_tfm(tfm); |
439 | } |
440 | |
441 | /** |
442 | * aead_request_alloc() - allocate request data structure |
443 | * @tfm: cipher handle to be registered with the request |
444 | * @gfp: memory allocation flag that is handed to kmalloc by the API call. |
445 | * |
446 | * Allocate the request data structure that must be used with the AEAD |
447 | * encrypt and decrypt API calls. During the allocation, the provided aead |
448 | * handle is registered in the request data structure. |
449 | * |
450 | * Return: allocated request handle in case of success, or NULL if out of memory |
451 | */ |
452 | static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm, |
453 | gfp_t gfp) |
454 | { |
455 | struct aead_request *req; |
456 | |
457 | req = kmalloc(size: sizeof(*req) + crypto_aead_reqsize(tfm), flags: gfp); |
458 | |
459 | if (likely(req)) |
460 | aead_request_set_tfm(req, tfm); |
461 | |
462 | return req; |
463 | } |
464 | |
465 | /** |
466 | * aead_request_free() - zeroize and free request data structure |
467 | * @req: request data structure cipher handle to be freed |
468 | */ |
469 | static inline void aead_request_free(struct aead_request *req) |
470 | { |
471 | kfree_sensitive(objp: req); |
472 | } |
473 | |
474 | /** |
475 | * aead_request_set_callback() - set asynchronous callback function |
476 | * @req: request handle |
477 | * @flags: specify zero or an ORing of the flags |
478 | * CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and |
479 | * increase the wait queue beyond the initial maximum size; |
480 | * CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep |
481 | * @compl: callback function pointer to be registered with the request handle |
482 | * @data: The data pointer refers to memory that is not used by the kernel |
483 | * crypto API, but provided to the callback function for it to use. Here, |
484 | * the caller can provide a reference to memory the callback function can |
485 | * operate on. As the callback function is invoked asynchronously to the |
486 | * related functionality, it may need to access data structures of the |
487 | * related functionality which can be referenced using this pointer. The |
488 | * callback function can access the memory via the "data" field in the |
489 | * crypto_async_request data structure provided to the callback function. |
490 | * |
491 | * Setting the callback function that is triggered once the cipher operation |
492 | * completes |
493 | * |
494 | * The callback function is registered with the aead_request handle and |
495 | * must comply with the following template:: |
496 | * |
497 | * void callback_function(struct crypto_async_request *req, int error) |
498 | */ |
499 | static inline void aead_request_set_callback(struct aead_request *req, |
500 | u32 flags, |
501 | crypto_completion_t compl, |
502 | void *data) |
503 | { |
504 | req->base.complete = compl; |
505 | req->base.data = data; |
506 | req->base.flags = flags; |
507 | } |
508 | |
509 | /** |
510 | * aead_request_set_crypt - set data buffers |
511 | * @req: request handle |
512 | * @src: source scatter / gather list |
513 | * @dst: destination scatter / gather list |
514 | * @cryptlen: number of bytes to process from @src |
515 | * @iv: IV for the cipher operation which must comply with the IV size defined |
516 | * by crypto_aead_ivsize() |
517 | * |
518 | * Setting the source data and destination data scatter / gather lists which |
519 | * hold the associated data concatenated with the plaintext or ciphertext. See |
520 | * below for the authentication tag. |
521 | * |
522 | * For encryption, the source is treated as the plaintext and the |
523 | * destination is the ciphertext. For a decryption operation, the use is |
524 | * reversed - the source is the ciphertext and the destination is the plaintext. |
525 | * |
526 | * The memory structure for cipher operation has the following structure: |
527 | * |
528 | * - AEAD encryption input: assoc data || plaintext |
529 | * - AEAD encryption output: assoc data || ciphertext || auth tag |
530 | * - AEAD decryption input: assoc data || ciphertext || auth tag |
531 | * - AEAD decryption output: assoc data || plaintext |
532 | * |
533 | * Albeit the kernel requires the presence of the AAD buffer, however, |
534 | * the kernel does not fill the AAD buffer in the output case. If the |
535 | * caller wants to have that data buffer filled, the caller must either |
536 | * use an in-place cipher operation (i.e. same memory location for |
537 | * input/output memory location). |
538 | */ |
539 | static inline void aead_request_set_crypt(struct aead_request *req, |
540 | struct scatterlist *src, |
541 | struct scatterlist *dst, |
542 | unsigned int cryptlen, u8 *iv) |
543 | { |
544 | req->src = src; |
545 | req->dst = dst; |
546 | req->cryptlen = cryptlen; |
547 | req->iv = iv; |
548 | } |
549 | |
550 | /** |
551 | * aead_request_set_ad - set associated data information |
552 | * @req: request handle |
553 | * @assoclen: number of bytes in associated data |
554 | * |
555 | * Setting the AD information. This function sets the length of |
556 | * the associated data. |
557 | */ |
558 | static inline void aead_request_set_ad(struct aead_request *req, |
559 | unsigned int assoclen) |
560 | { |
561 | req->assoclen = assoclen; |
562 | } |
563 | |
564 | #endif /* _CRYPTO_AEAD_H */ |
565 | |