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 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 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 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 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 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 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 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 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 */