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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 : : * To support the needs of the most prominent user of AEAD ciphers, namely
47 : : * IPSEC, the AEAD ciphers have a special memory layout the caller must adhere
48 : : * to.
49 : : *
50 : : * The scatter list pointing to the input data must contain:
51 : : *
52 : : * * for RFC4106 ciphers, the concatenation of
53 : : * associated authentication data || IV || plaintext or ciphertext. Note, the
54 : : * same IV (buffer) is also set with the aead_request_set_crypt call. Note,
55 : : * the API call of aead_request_set_ad must provide the length of the AAD and
56 : : * the IV. The API call of aead_request_set_crypt only points to the size of
57 : : * the input plaintext or ciphertext.
58 : : *
59 : : * * for "normal" AEAD ciphers, the concatenation of
60 : : * associated authentication data || plaintext or ciphertext.
61 : : *
62 : : * It is important to note that if multiple scatter gather list entries form
63 : : * the input data mentioned above, the first entry must not point to a NULL
64 : : * buffer. If there is any potential where the AAD buffer can be NULL, the
65 : : * calling code must contain a precaution to ensure that this does not result
66 : : * in the first scatter gather list entry pointing to a NULL buffer.
67 : : */
68 : :
69 : : struct crypto_aead;
70 : :
71 : : /**
72 : : * struct aead_request - AEAD request
73 : : * @base: Common attributes for async crypto requests
74 : : * @assoclen: Length in bytes of associated data for authentication
75 : : * @cryptlen: Length of data to be encrypted or decrypted
76 : : * @iv: Initialisation vector
77 : : * @src: Source data
78 : : * @dst: Destination data
79 : : * @__ctx: Start of private context data
80 : : */
81 : : struct aead_request {
82 : : struct crypto_async_request base;
83 : :
84 : : unsigned int assoclen;
85 : : unsigned int cryptlen;
86 : :
87 : : u8 *iv;
88 : :
89 : : struct scatterlist *src;
90 : : struct scatterlist *dst;
91 : :
92 : : void *__ctx[] CRYPTO_MINALIGN_ATTR;
93 : : };
94 : :
95 : : /**
96 : : * struct aead_alg - AEAD cipher definition
97 : : * @maxauthsize: Set the maximum authentication tag size supported by the
98 : : * transformation. A transformation may support smaller tag sizes.
99 : : * As the authentication tag is a message digest to ensure the
100 : : * integrity of the encrypted data, a consumer typically wants the
101 : : * largest authentication tag possible as defined by this
102 : : * variable.
103 : : * @setauthsize: Set authentication size for the AEAD transformation. This
104 : : * function is used to specify the consumer requested size of the
105 : : * authentication tag to be either generated by the transformation
106 : : * during encryption or the size of the authentication tag to be
107 : : * supplied during the decryption operation. This function is also
108 : : * responsible for checking the authentication tag size for
109 : : * validity.
110 : : * @setkey: see struct skcipher_alg
111 : : * @encrypt: see struct skcipher_alg
112 : : * @decrypt: see struct skcipher_alg
113 : : * @ivsize: see struct skcipher_alg
114 : : * @chunksize: see struct skcipher_alg
115 : : * @init: Initialize the cryptographic transformation object. This function
116 : : * is used to initialize the cryptographic transformation object.
117 : : * This function is called only once at the instantiation time, right
118 : : * after the transformation context was allocated. In case the
119 : : * cryptographic hardware has some special requirements which need to
120 : : * be handled by software, this function shall check for the precise
121 : : * requirement of the transformation and put any software fallbacks
122 : : * in place.
123 : : * @exit: Deinitialize the cryptographic transformation object. This is a
124 : : * counterpart to @init, used to remove various changes set in
125 : : * @init.
126 : : * @base: Definition of a generic crypto cipher algorithm.
127 : : *
128 : : * All fields except @ivsize is mandatory and must be filled.
129 : : */
130 : : struct aead_alg {
131 : : int (*setkey)(struct crypto_aead *tfm, const u8 *key,
132 : : unsigned int keylen);
133 : : int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize);
134 : : int (*encrypt)(struct aead_request *req);
135 : : int (*decrypt)(struct aead_request *req);
136 : : int (*init)(struct crypto_aead *tfm);
137 : : void (*exit)(struct crypto_aead *tfm);
138 : :
139 : : unsigned int ivsize;
140 : : unsigned int maxauthsize;
141 : : unsigned int chunksize;
142 : :
143 : : struct crypto_alg base;
144 : : };
145 : :
146 : : struct crypto_aead {
147 : : unsigned int authsize;
148 : : unsigned int reqsize;
149 : :
150 : : struct crypto_tfm base;
151 : : };
152 : :
153 : : static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
154 : : {
155 : 0 : return container_of(tfm, struct crypto_aead, base);
156 : : }
157 : :
158 : : /**
159 : : * crypto_alloc_aead() - allocate AEAD cipher handle
160 : : * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
161 : : * AEAD cipher
162 : : * @type: specifies the type of the cipher
163 : : * @mask: specifies the mask for the cipher
164 : : *
165 : : * Allocate a cipher handle for an AEAD. The returned struct
166 : : * crypto_aead is the cipher handle that is required for any subsequent
167 : : * API invocation for that AEAD.
168 : : *
169 : : * Return: allocated cipher handle in case of success; IS_ERR() is true in case
170 : : * of an error, PTR_ERR() returns the error code.
171 : : */
172 : : struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);
173 : :
174 : : static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
175 : : {
176 : 0 : return &tfm->base;
177 : : }
178 : :
179 : : /**
180 : : * crypto_free_aead() - zeroize and free aead handle
181 : : * @tfm: cipher handle to be freed
182 : : */
183 : : static inline void crypto_free_aead(struct crypto_aead *tfm)
184 : : {
185 : 0 : crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
186 : : }
187 : :
188 : : static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
189 : : {
190 : 0 : return container_of(crypto_aead_tfm(tfm)->__crt_alg,
191 : : struct aead_alg, base);
192 : : }
193 : :
194 : : static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
195 : : {
196 : 0 : return alg->ivsize;
197 : : }
198 : :
199 : : /**
200 : : * crypto_aead_ivsize() - obtain IV size
201 : : * @tfm: cipher handle
202 : : *
203 : : * The size of the IV for the aead referenced by the cipher handle is
204 : : * returned. This IV size may be zero if the cipher does not need an IV.
205 : : *
206 : : * Return: IV size in bytes
207 : : */
208 : : static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)
209 : : {
210 : : return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
211 : : }
212 : :
213 : : /**
214 : : * crypto_aead_authsize() - obtain maximum authentication data size
215 : : * @tfm: cipher handle
216 : : *
217 : : * The maximum size of the authentication data for the AEAD cipher referenced
218 : : * by the AEAD cipher handle is returned. The authentication data size may be
219 : : * zero if the cipher implements a hard-coded maximum.
220 : : *
221 : : * The authentication data may also be known as "tag value".
222 : : *
223 : : * Return: authentication data size / tag size in bytes
224 : : */
225 : : static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)
226 : : {
227 : 0 : return tfm->authsize;
228 : : }
229 : :
230 : : /**
231 : : * crypto_aead_blocksize() - obtain block size of cipher
232 : : * @tfm: cipher handle
233 : : *
234 : : * The block size for the AEAD referenced with the cipher handle is returned.
235 : : * The caller may use that information to allocate appropriate memory for the
236 : : * data returned by the encryption or decryption operation
237 : : *
238 : : * Return: block size of cipher
239 : : */
240 : : static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
241 : : {
242 : : return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
243 : : }
244 : :
245 : : static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
246 : : {
247 : : return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));
248 : : }
249 : :
250 : : static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)
251 : : {
252 : : return crypto_tfm_get_flags(crypto_aead_tfm(tfm));
253 : : }
254 : :
255 : : static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)
256 : : {
257 : : crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);
258 : : }
259 : :
260 : : static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)
261 : : {
262 : : crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
263 : : }
264 : :
265 : : /**
266 : : * crypto_aead_setkey() - set key for cipher
267 : : * @tfm: cipher handle
268 : : * @key: buffer holding the key
269 : : * @keylen: length of the key in bytes
270 : : *
271 : : * The caller provided key is set for the AEAD referenced by the cipher
272 : : * handle.
273 : : *
274 : : * Note, the key length determines the cipher type. Many block ciphers implement
275 : : * different cipher modes depending on the key size, such as AES-128 vs AES-192
276 : : * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
277 : : * is performed.
278 : : *
279 : : * Return: 0 if the setting of the key was successful; < 0 if an error occurred
280 : : */
281 : : int crypto_aead_setkey(struct crypto_aead *tfm,
282 : : const u8 *key, unsigned int keylen);
283 : :
284 : : /**
285 : : * crypto_aead_setauthsize() - set authentication data size
286 : : * @tfm: cipher handle
287 : : * @authsize: size of the authentication data / tag in bytes
288 : : *
289 : : * Set the authentication data size / tag size. AEAD requires an authentication
290 : : * tag (or MAC) in addition to the associated data.
291 : : *
292 : : * Return: 0 if the setting of the key was successful; < 0 if an error occurred
293 : : */
294 : : int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);
295 : :
296 : : static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
297 : : {
298 : 0 : return __crypto_aead_cast(req->base.tfm);
299 : : }
300 : :
301 : : /**
302 : : * crypto_aead_encrypt() - encrypt plaintext
303 : : * @req: reference to the aead_request handle that holds all information
304 : : * needed to perform the cipher operation
305 : : *
306 : : * Encrypt plaintext data using the aead_request handle. That data structure
307 : : * and how it is filled with data is discussed with the aead_request_*
308 : : * functions.
309 : : *
310 : : * IMPORTANT NOTE The encryption operation creates the authentication data /
311 : : * tag. That data is concatenated with the created ciphertext.
312 : : * The ciphertext memory size is therefore the given number of
313 : : * block cipher blocks + the size defined by the
314 : : * crypto_aead_setauthsize invocation. The caller must ensure
315 : : * that sufficient memory is available for the ciphertext and
316 : : * the authentication tag.
317 : : *
318 : : * Return: 0 if the cipher operation was successful; < 0 if an error occurred
319 : : */
320 : : int crypto_aead_encrypt(struct aead_request *req);
321 : :
322 : : /**
323 : : * crypto_aead_decrypt() - decrypt ciphertext
324 : : * @req: reference to the ablkcipher_request handle that holds all information
325 : : * needed to perform the cipher operation
326 : : *
327 : : * Decrypt ciphertext 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 caller must concatenate the ciphertext followed by the
332 : : * authentication data / tag. That authentication data / tag
333 : : * must have the size defined by the crypto_aead_setauthsize
334 : : * invocation.
335 : : *
336 : : *
337 : : * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
338 : : * cipher operation performs the authentication of the data during the
339 : : * decryption operation. Therefore, the function returns this error if
340 : : * the authentication of the ciphertext was unsuccessful (i.e. the
341 : : * integrity of the ciphertext or the associated data was violated);
342 : : * < 0 if an error occurred.
343 : : */
344 : : int crypto_aead_decrypt(struct aead_request *req);
345 : :
346 : : /**
347 : : * DOC: Asynchronous AEAD Request Handle
348 : : *
349 : : * The aead_request data structure contains all pointers to data required for
350 : : * the AEAD cipher operation. This includes the cipher handle (which can be
351 : : * used by multiple aead_request instances), pointer to plaintext and
352 : : * ciphertext, asynchronous callback function, etc. It acts as a handle to the
353 : : * aead_request_* API calls in a similar way as AEAD handle to the
354 : : * crypto_aead_* API calls.
355 : : */
356 : :
357 : : /**
358 : : * crypto_aead_reqsize() - obtain size of the request data structure
359 : : * @tfm: cipher handle
360 : : *
361 : : * Return: number of bytes
362 : : */
363 : : static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)
364 : : {
365 : 0 : return tfm->reqsize;
366 : : }
367 : :
368 : : /**
369 : : * aead_request_set_tfm() - update cipher handle reference in request
370 : : * @req: request handle to be modified
371 : : * @tfm: cipher handle that shall be added to the request handle
372 : : *
373 : : * Allow the caller to replace the existing aead handle in the request
374 : : * data structure with a different one.
375 : : */
376 : : static inline void aead_request_set_tfm(struct aead_request *req,
377 : : struct crypto_aead *tfm)
378 : : {
379 : : req->base.tfm = crypto_aead_tfm(tfm);
380 : : }
381 : :
382 : : /**
383 : : * aead_request_alloc() - allocate request data structure
384 : : * @tfm: cipher handle to be registered with the request
385 : : * @gfp: memory allocation flag that is handed to kmalloc by the API call.
386 : : *
387 : : * Allocate the request data structure that must be used with the AEAD
388 : : * encrypt and decrypt API calls. During the allocation, the provided aead
389 : : * handle is registered in the request data structure.
390 : : *
391 : : * Return: allocated request handle in case of success, or NULL if out of memory
392 : : */
393 : : static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
394 : : gfp_t gfp)
395 : : {
396 : : struct aead_request *req;
397 : :
398 : : req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);
399 : :
400 : : if (likely(req))
401 : : aead_request_set_tfm(req, tfm);
402 : :
403 : : return req;
404 : : }
405 : :
406 : : /**
407 : : * aead_request_free() - zeroize and free request data structure
408 : : * @req: request data structure cipher handle to be freed
409 : : */
410 : : static inline void aead_request_free(struct aead_request *req)
411 : : {
412 : : kzfree(req);
413 : : }
414 : :
415 : : /**
416 : : * aead_request_set_callback() - set asynchronous callback function
417 : : * @req: request handle
418 : : * @flags: specify zero or an ORing of the flags
419 : : * CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
420 : : * increase the wait queue beyond the initial maximum size;
421 : : * CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
422 : : * @compl: callback function pointer to be registered with the request handle
423 : : * @data: The data pointer refers to memory that is not used by the kernel
424 : : * crypto API, but provided to the callback function for it to use. Here,
425 : : * the caller can provide a reference to memory the callback function can
426 : : * operate on. As the callback function is invoked asynchronously to the
427 : : * related functionality, it may need to access data structures of the
428 : : * related functionality which can be referenced using this pointer. The
429 : : * callback function can access the memory via the "data" field in the
430 : : * crypto_async_request data structure provided to the callback function.
431 : : *
432 : : * Setting the callback function that is triggered once the cipher operation
433 : : * completes
434 : : *
435 : : * The callback function is registered with the aead_request handle and
436 : : * must comply with the following template::
437 : : *
438 : : * void callback_function(struct crypto_async_request *req, int error)
439 : : */
440 : : static inline void aead_request_set_callback(struct aead_request *req,
441 : : u32 flags,
442 : : crypto_completion_t compl,
443 : : void *data)
444 : : {
445 : : req->base.complete = compl;
446 : : req->base.data = data;
447 : : req->base.flags = flags;
448 : : }
449 : :
450 : : /**
451 : : * aead_request_set_crypt - set data buffers
452 : : * @req: request handle
453 : : * @src: source scatter / gather list
454 : : * @dst: destination scatter / gather list
455 : : * @cryptlen: number of bytes to process from @src
456 : : * @iv: IV for the cipher operation which must comply with the IV size defined
457 : : * by crypto_aead_ivsize()
458 : : *
459 : : * Setting the source data and destination data scatter / gather lists which
460 : : * hold the associated data concatenated with the plaintext or ciphertext. See
461 : : * below for the authentication tag.
462 : : *
463 : : * For encryption, the source is treated as the plaintext and the
464 : : * destination is the ciphertext. For a decryption operation, the use is
465 : : * reversed - the source is the ciphertext and the destination is the plaintext.
466 : : *
467 : : * The memory structure for cipher operation has the following structure:
468 : : *
469 : : * - AEAD encryption input: assoc data || plaintext
470 : : * - AEAD encryption output: assoc data || cipherntext || auth tag
471 : : * - AEAD decryption input: assoc data || ciphertext || auth tag
472 : : * - AEAD decryption output: assoc data || plaintext
473 : : *
474 : : * Albeit the kernel requires the presence of the AAD buffer, however,
475 : : * the kernel does not fill the AAD buffer in the output case. If the
476 : : * caller wants to have that data buffer filled, the caller must either
477 : : * use an in-place cipher operation (i.e. same memory location for
478 : : * input/output memory location).
479 : : */
480 : : static inline void aead_request_set_crypt(struct aead_request *req,
481 : : struct scatterlist *src,
482 : : struct scatterlist *dst,
483 : : unsigned int cryptlen, u8 *iv)
484 : : {
485 : : req->src = src;
486 : : req->dst = dst;
487 : : req->cryptlen = cryptlen;
488 : : req->iv = iv;
489 : : }
490 : :
491 : : /**
492 : : * aead_request_set_ad - set associated data information
493 : : * @req: request handle
494 : : * @assoclen: number of bytes in associated data
495 : : *
496 : : * Setting the AD information. This function sets the length of
497 : : * the associated data.
498 : : */
499 : : static inline void aead_request_set_ad(struct aead_request *req,
500 : : unsigned int assoclen)
501 : : {
502 : : req->assoclen = assoclen;
503 : : }
504 : :
505 : : #endif /* _CRYPTO_AEAD_H */
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