aead.h

  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
 77struct crypto_aead;
 78struct 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 */
 90struct 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 */
139struct 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
155struct crypto_aead {
156	unsigned int authsize;
157	unsigned int reqsize;
158
159	struct crypto_tfm base;
160};
161
162struct crypto_sync_aead {
163	struct crypto_aead base;
164};
165
166#define MAX_SYNC_AEAD_REQSIZE		384
167
168#define SYNC_AEAD_REQUEST_ON_STACK(name, _tfm)		\
169	char __##name##_desc[sizeof(struct aead_request) +	\
170			     MAX_SYNC_AEAD_REQSIZE		\
171			    ] CRYPTO_MINALIGN_ATTR;		\
172	struct aead_request *name =				\
173		(((struct aead_request *)__##name##_desc)->base.tfm = \
174			crypto_sync_aead_tfm((_tfm)),		\
175		 (void *)__##name##_desc)
176
177static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
178{
179	return container_of(tfm, struct crypto_aead, base);
180}
181
182/**
183 * crypto_alloc_aead() - allocate AEAD cipher handle
184 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
185 *	     AEAD cipher
186 * @type: specifies the type of the cipher
187 * @mask: specifies the mask for the cipher
188 *
189 * Allocate a cipher handle for an AEAD. The returned struct
190 * crypto_aead is the cipher handle that is required for any subsequent
191 * API invocation for that AEAD.
192 *
193 * Return: allocated cipher handle in case of success; IS_ERR() is true in case
194 *	   of an error, PTR_ERR() returns the error code.
195 */
196struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);
197
198struct crypto_sync_aead *crypto_alloc_sync_aead(const char *alg_name, u32 type, u32 mask);
199
200static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
201{
202	return &tfm->base;
203}
204
205static inline struct crypto_tfm *crypto_sync_aead_tfm(struct crypto_sync_aead *tfm)
206{
207	return crypto_aead_tfm(&tfm->base);
208}
209
210/**
211 * crypto_free_aead() - zeroize and free aead handle
212 * @tfm: cipher handle to be freed
213 *
214 * If @tfm is a NULL or error pointer, this function does nothing.
215 */
216static inline void crypto_free_aead(struct crypto_aead *tfm)
217{
218	crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
219}
220
221static inline void crypto_free_sync_aead(struct crypto_sync_aead *tfm)
222{
223	crypto_free_aead(&tfm->base);
224}
225
226/**
227 * crypto_has_aead() - Search for the availability of an aead.
228 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
229 *	      aead
230 * @type: specifies the type of the aead
231 * @mask: specifies the mask for the aead
232 *
233 * Return: true when the aead is known to the kernel crypto API; false
234 *	   otherwise
235 */
236int crypto_has_aead(const char *alg_name, u32 type, u32 mask);
237
238static inline const char *crypto_aead_driver_name(struct crypto_aead *tfm)
239{
240	return crypto_tfm_alg_driver_name(crypto_aead_tfm(tfm));
241}
242
243static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
244{
245	return container_of(crypto_aead_tfm(tfm)->__crt_alg,
246			    struct aead_alg, base);
247}
248
249static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
250{
251	return alg->ivsize;
252}
253
254/**
255 * crypto_aead_ivsize() - obtain IV size
256 * @tfm: cipher handle
257 *
258 * The size of the IV for the aead referenced by the cipher handle is
259 * returned. This IV size may be zero if the cipher does not need an IV.
260 *
261 * Return: IV size in bytes
262 */
263static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)
264{
265	return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
266}
267
268static inline unsigned int crypto_sync_aead_ivsize(struct crypto_sync_aead *tfm)
269{
270	return crypto_aead_ivsize(&tfm->base);
271}
272
273/**
274 * crypto_aead_authsize() - obtain maximum authentication data size
275 * @tfm: cipher handle
276 *
277 * The maximum size of the authentication data for the AEAD cipher referenced
278 * by the AEAD cipher handle is returned. The authentication data size may be
279 * zero if the cipher implements a hard-coded maximum.
280 *
281 * The authentication data may also be known as "tag value".
282 *
283 * Return: authentication data size / tag size in bytes
284 */
285static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)
286{
287	return tfm->authsize;
288}
289
290static inline unsigned int crypto_sync_aead_authsize(struct crypto_sync_aead *tfm)
291{
292	return crypto_aead_authsize(&tfm->base);
293}
294
295static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg)
296{
297	return alg->maxauthsize;
298}
299
300static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead)
301{
302	return crypto_aead_alg_maxauthsize(crypto_aead_alg(aead));
303}
304
305static inline unsigned int crypto_sync_aead_maxauthsize(struct crypto_sync_aead *tfm)
306{
307	return crypto_aead_maxauthsize(&tfm->base);
308}
309
310/**
311 * crypto_aead_blocksize() - obtain block size of cipher
312 * @tfm: cipher handle
313 *
314 * The block size for the AEAD referenced with the cipher handle is returned.
315 * The caller may use that information to allocate appropriate memory for the
316 * data returned by the encryption or decryption operation
317 *
318 * Return: block size of cipher
319 */
320static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
321{
322	return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
323}
324
325static inline unsigned int crypto_sync_aead_blocksize(struct crypto_sync_aead *tfm)
326{
327	return crypto_aead_blocksize(&tfm->base);
328}
329
330static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
331{
332	return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));
333}
334
335static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)
336{
337	return crypto_tfm_get_flags(crypto_aead_tfm(tfm));
338}
339
340static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)
341{
342	crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);
343}
344
345static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)
346{
347	crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
348}
349
350static inline u32 crypto_sync_aead_get_flags(struct crypto_sync_aead *tfm)
351{
352	return crypto_aead_get_flags(&tfm->base);
353}
354
355static inline void crypto_sync_aead_set_flags(struct crypto_sync_aead *tfm, u32 flags)
356{
357	crypto_aead_set_flags(&tfm->base, flags);
358}
359
360static inline void crypto_sync_aead_clear_flags(struct crypto_sync_aead *tfm, u32 flags)
361{
362	crypto_aead_clear_flags(&tfm->base, flags);
363}
364
365/**
366 * crypto_aead_setkey() - set key for cipher
367 * @tfm: cipher handle
368 * @key: buffer holding the key
369 * @keylen: length of the key in bytes
370 *
371 * The caller provided key is set for the AEAD referenced by the cipher
372 * handle.
373 *
374 * Note, the key length determines the cipher type. Many block ciphers implement
375 * different cipher modes depending on the key size, such as AES-128 vs AES-192
376 * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
377 * is performed.
378 *
379 * Return: 0 if the setting of the key was successful; < 0 if an error occurred
380 */
381int crypto_aead_setkey(struct crypto_aead *tfm,
382		       const u8 *key, unsigned int keylen);
383
384static inline int crypto_sync_aead_setkey(struct crypto_sync_aead *tfm,
385					 const u8 *key, unsigned int keylen)
386{
387	return crypto_aead_setkey(&tfm->base, key, keylen);
388}
389
390/**
391 * crypto_aead_setauthsize() - set authentication data size
392 * @tfm: cipher handle
393 * @authsize: size of the authentication data / tag in bytes
394 *
395 * Set the authentication data size / tag size. AEAD requires an authentication
396 * tag (or MAC) in addition to the associated data.
397 *
398 * Return: 0 if the setting of the key was successful; < 0 if an error occurred
399 */
400int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);
401
402static inline int crypto_sync_aead_setauthsize(struct crypto_sync_aead *tfm,
403					       unsigned int authsize)
404{
405	return crypto_aead_setauthsize(&tfm->base, authsize);
406}
407
408static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
409{
410	return __crypto_aead_cast(req->base.tfm);
411}
412
413static inline struct crypto_sync_aead *crypto_sync_aead_reqtfm(struct aead_request *req)
414{
415	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
416
417	return container_of(tfm, struct crypto_sync_aead, base);
418}
419
420/**
421 * crypto_aead_encrypt() - encrypt plaintext
422 * @req: reference to the aead_request handle that holds all information
423 *	 needed to perform the cipher operation
424 *
425 * Encrypt plaintext data using the aead_request handle. That data structure
426 * and how it is filled with data is discussed with the aead_request_*
427 * functions.
428 *
429 * IMPORTANT NOTE The encryption operation creates the authentication data /
430 *		  tag. That data is concatenated with the created ciphertext.
431 *		  The ciphertext memory size is therefore the given number of
432 *		  block cipher blocks + the size defined by the
433 *		  crypto_aead_setauthsize invocation. The caller must ensure
434 *		  that sufficient memory is available for the ciphertext and
435 *		  the authentication tag.
436 *
437 * Return: 0 if the cipher operation was successful; < 0 if an error occurred
438 */
439int crypto_aead_encrypt(struct aead_request *req);
440
441/**
442 * crypto_aead_decrypt() - decrypt ciphertext
443 * @req: reference to the aead_request handle that holds all information
444 *	 needed to perform the cipher operation
445 *
446 * Decrypt ciphertext data using the aead_request handle. That data structure
447 * and how it is filled with data is discussed with the aead_request_*
448 * functions.
449 *
450 * IMPORTANT NOTE The caller must concatenate the ciphertext followed by the
451 *		  authentication data / tag. That authentication data / tag
452 *		  must have the size defined by the crypto_aead_setauthsize
453 *		  invocation.
454 *
455 *
456 * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
457 *	   cipher operation performs the authentication of the data during the
458 *	   decryption operation. Therefore, the function returns this error if
459 *	   the authentication of the ciphertext was unsuccessful (i.e. the
460 *	   integrity of the ciphertext or the associated data was violated);
461 *	   < 0 if an error occurred.
462 */
463int crypto_aead_decrypt(struct aead_request *req);
464
465/**
466 * DOC: Asynchronous AEAD Request Handle
467 *
468 * The aead_request data structure contains all pointers to data required for
469 * the AEAD cipher operation. This includes the cipher handle (which can be
470 * used by multiple aead_request instances), pointer to plaintext and
471 * ciphertext, asynchronous callback function, etc. It acts as a handle to the
472 * aead_request_* API calls in a similar way as AEAD handle to the
473 * crypto_aead_* API calls.
474 */
475
476/**
477 * crypto_aead_reqsize() - obtain size of the request data structure
478 * @tfm: cipher handle
479 *
480 * Return: number of bytes
481 */
482static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)
483{
484	return tfm->reqsize;
485}
486
487/**
488 * aead_request_set_tfm() - update cipher handle reference in request
489 * @req: request handle to be modified
490 * @tfm: cipher handle that shall be added to the request handle
491 *
492 * Allow the caller to replace the existing aead handle in the request
493 * data structure with a different one.
494 */
495static inline void aead_request_set_tfm(struct aead_request *req,
496					struct crypto_aead *tfm)
497{
498	req->base.tfm = crypto_aead_tfm(tfm);
499}
500
501static inline void aead_request_set_sync_tfm(struct aead_request *req,
502					     struct crypto_sync_aead *tfm)
503{
504	aead_request_set_tfm(req, &tfm->base);
505}
506
507/**
508 * aead_request_alloc() - allocate request data structure
509 * @tfm: cipher handle to be registered with the request
510 * @gfp: memory allocation flag that is handed to kmalloc by the API call.
511 *
512 * Allocate the request data structure that must be used with the AEAD
513 * encrypt and decrypt API calls. During the allocation, the provided aead
514 * handle is registered in the request data structure.
515 *
516 * Return: allocated request handle in case of success, or NULL if out of memory
517 */
518static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
519						      gfp_t gfp)
520{
521	struct aead_request *req;
522
523	req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);
524
525	if (likely(req))
526		aead_request_set_tfm(req, tfm);
527
528	return req;
529}
530
531/**
532 * aead_request_free() - zeroize and free request data structure
533 * @req: request data structure cipher handle to be freed
534 */
535static inline void aead_request_free(struct aead_request *req)
536{
537	kfree_sensitive(req);
538}
539
540/**
541 * aead_request_set_callback() - set asynchronous callback function
542 * @req: request handle
543 * @flags: specify zero or an ORing of the flags
544 *	   CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
545 *	   increase the wait queue beyond the initial maximum size;
546 *	   CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
547 * @compl: callback function pointer to be registered with the request handle
548 * @data: The data pointer refers to memory that is not used by the kernel
549 *	  crypto API, but provided to the callback function for it to use. Here,
550 *	  the caller can provide a reference to memory the callback function can
551 *	  operate on. As the callback function is invoked asynchronously to the
552 *	  related functionality, it may need to access data structures of the
553 *	  related functionality which can be referenced using this pointer. The
554 *	  callback function can access the memory via the "data" field in the
555 *	  crypto_async_request data structure provided to the callback function.
556 *
557 * Setting the callback function that is triggered once the cipher operation
558 * completes
559 *
560 * The callback function is registered with the aead_request handle and
561 * must comply with the following template::
562 *
563 *	void callback_function(struct crypto_async_request *req, int error)
564 */
565static inline void aead_request_set_callback(struct aead_request *req,
566					     u32 flags,
567					     crypto_completion_t compl,
568					     void *data)
569{
570	req->base.complete = compl;
571	req->base.data = data;
572	req->base.flags = flags;
573}
574
575/**
576 * aead_request_set_crypt - set data buffers
577 * @req: request handle
578 * @src: source scatter / gather list
579 * @dst: destination scatter / gather list
580 * @cryptlen: number of bytes to process from @src
581 * @iv: IV for the cipher operation which must comply with the IV size defined
582 *      by crypto_aead_ivsize()
583 *
584 * Setting the source data and destination data scatter / gather lists which
585 * hold the associated data concatenated with the plaintext or ciphertext. See
586 * below for the authentication tag.
587 *
588 * For encryption, the source is treated as the plaintext and the
589 * destination is the ciphertext. For a decryption operation, the use is
590 * reversed - the source is the ciphertext and the destination is the plaintext.
591 *
592 * The memory structure for cipher operation has the following structure:
593 *
594 * - AEAD encryption input:  assoc data || plaintext
595 * - AEAD encryption output: assoc data || ciphertext || auth tag
596 * - AEAD decryption input:  assoc data || ciphertext || auth tag
597 * - AEAD decryption output: assoc data || plaintext
598 *
599 * Albeit the kernel requires the presence of the AAD buffer, however,
600 * the kernel does not fill the AAD buffer in the output case. If the
601 * caller wants to have that data buffer filled, the caller must either
602 * use an in-place cipher operation (i.e. same memory location for
603 * input/output memory location).
604 */
605static inline void aead_request_set_crypt(struct aead_request *req,
606					  struct scatterlist *src,
607					  struct scatterlist *dst,
608					  unsigned int cryptlen, u8 *iv)
609{
610	req->src = src;
611	req->dst = dst;
612	req->cryptlen = cryptlen;
613	req->iv = iv;
614}
615
616/**
617 * aead_request_set_ad - set associated data information
618 * @req: request handle
619 * @assoclen: number of bytes in associated data
620 *
621 * Setting the AD information.  This function sets the length of
622 * the associated data.
623 */
624static inline void aead_request_set_ad(struct aead_request *req,
625				       unsigned int assoclen)
626{
627	req->assoclen = assoclen;
628}
629
630#endif	/* _CRYPTO_AEAD_H */