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