xref: /linux/include/crypto/aead.h (revision 621cde16e49b3ecf7d59a8106a20aaebfb4a59a9)
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 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  */
139 struct 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 
155 struct crypto_aead {
156 	unsigned int authsize;
157 	unsigned int reqsize;
158 
159 	struct crypto_tfm base;
160 };
161 
__crypto_aead_cast(struct crypto_tfm * tfm)162 static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
163 {
164 	return container_of(tfm, struct crypto_aead, base);
165 }
166 
167 /**
168  * crypto_alloc_aead() - allocate AEAD cipher handle
169  * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
170  *	     AEAD cipher
171  * @type: specifies the type of the cipher
172  * @mask: specifies the mask for the cipher
173  *
174  * Allocate a cipher handle for an AEAD. The returned struct
175  * crypto_aead is the cipher handle that is required for any subsequent
176  * API invocation for that AEAD.
177  *
178  * Return: allocated cipher handle in case of success; IS_ERR() is true in case
179  *	   of an error, PTR_ERR() returns the error code.
180  */
181 struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);
182 
crypto_aead_tfm(struct crypto_aead * tfm)183 static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
184 {
185 	return &tfm->base;
186 }
187 
188 /**
189  * crypto_free_aead() - zeroize and free aead handle
190  * @tfm: cipher handle to be freed
191  *
192  * If @tfm is a NULL or error pointer, this function does nothing.
193  */
crypto_free_aead(struct crypto_aead * tfm)194 static inline void crypto_free_aead(struct crypto_aead *tfm)
195 {
196 	crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
197 }
198 
199 /**
200  * crypto_has_aead() - Search for the availability of an aead.
201  * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
202  *	      aead
203  * @type: specifies the type of the aead
204  * @mask: specifies the mask for the aead
205  *
206  * Return: true when the aead is known to the kernel crypto API; false
207  *	   otherwise
208  */
209 int crypto_has_aead(const char *alg_name, u32 type, u32 mask);
210 
crypto_aead_driver_name(struct crypto_aead * tfm)211 static inline const char *crypto_aead_driver_name(struct crypto_aead *tfm)
212 {
213 	return crypto_tfm_alg_driver_name(crypto_aead_tfm(tfm));
214 }
215 
crypto_aead_alg(struct crypto_aead * tfm)216 static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
217 {
218 	return container_of(crypto_aead_tfm(tfm)->__crt_alg,
219 			    struct aead_alg, base);
220 }
221 
crypto_aead_alg_ivsize(struct aead_alg * alg)222 static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
223 {
224 	return alg->ivsize;
225 }
226 
227 /**
228  * crypto_aead_ivsize() - obtain IV size
229  * @tfm: cipher handle
230  *
231  * The size of the IV for the aead referenced by the cipher handle is
232  * returned. This IV size may be zero if the cipher does not need an IV.
233  *
234  * Return: IV size in bytes
235  */
crypto_aead_ivsize(struct crypto_aead * tfm)236 static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)
237 {
238 	return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
239 }
240 
241 /**
242  * crypto_aead_authsize() - obtain maximum authentication data size
243  * @tfm: cipher handle
244  *
245  * The maximum size of the authentication data for the AEAD cipher referenced
246  * by the AEAD cipher handle is returned. The authentication data size may be
247  * zero if the cipher implements a hard-coded maximum.
248  *
249  * The authentication data may also be known as "tag value".
250  *
251  * Return: authentication data size / tag size in bytes
252  */
crypto_aead_authsize(struct crypto_aead * tfm)253 static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)
254 {
255 	return tfm->authsize;
256 }
257 
crypto_aead_alg_maxauthsize(struct aead_alg * alg)258 static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg)
259 {
260 	return alg->maxauthsize;
261 }
262 
crypto_aead_maxauthsize(struct crypto_aead * aead)263 static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead)
264 {
265 	return crypto_aead_alg_maxauthsize(crypto_aead_alg(aead));
266 }
267 
268 /**
269  * crypto_aead_blocksize() - obtain block size of cipher
270  * @tfm: cipher handle
271  *
272  * The block size for the AEAD referenced with the cipher handle is returned.
273  * The caller may use that information to allocate appropriate memory for the
274  * data returned by the encryption or decryption operation
275  *
276  * Return: block size of cipher
277  */
crypto_aead_blocksize(struct crypto_aead * tfm)278 static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
279 {
280 	return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
281 }
282 
crypto_aead_alignmask(struct crypto_aead * tfm)283 static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
284 {
285 	return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));
286 }
287 
crypto_aead_get_flags(struct crypto_aead * tfm)288 static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)
289 {
290 	return crypto_tfm_get_flags(crypto_aead_tfm(tfm));
291 }
292 
crypto_aead_set_flags(struct crypto_aead * tfm,u32 flags)293 static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)
294 {
295 	crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);
296 }
297 
crypto_aead_clear_flags(struct crypto_aead * tfm,u32 flags)298 static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)
299 {
300 	crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
301 }
302 
303 /**
304  * crypto_aead_setkey() - set key for cipher
305  * @tfm: cipher handle
306  * @key: buffer holding the key
307  * @keylen: length of the key in bytes
308  *
309  * The caller provided key is set for the AEAD referenced by the cipher
310  * handle.
311  *
312  * Note, the key length determines the cipher type. Many block ciphers implement
313  * different cipher modes depending on the key size, such as AES-128 vs AES-192
314  * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
315  * is performed.
316  *
317  * Return: 0 if the setting of the key was successful; < 0 if an error occurred
318  */
319 int crypto_aead_setkey(struct crypto_aead *tfm,
320 		       const u8 *key, unsigned int keylen);
321 
322 /**
323  * crypto_aead_setauthsize() - set authentication data size
324  * @tfm: cipher handle
325  * @authsize: size of the authentication data / tag in bytes
326  *
327  * Set the authentication data size / tag size. AEAD requires an authentication
328  * tag (or MAC) in addition to the associated data.
329  *
330  * Return: 0 if the setting of the key was successful; < 0 if an error occurred
331  */
332 int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);
333 
crypto_aead_reqtfm(struct aead_request * req)334 static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
335 {
336 	return __crypto_aead_cast(req->base.tfm);
337 }
338 
339 /**
340  * crypto_aead_encrypt() - encrypt plaintext
341  * @req: reference to the aead_request handle that holds all information
342  *	 needed to perform the cipher operation
343  *
344  * Encrypt plaintext data using the aead_request handle. That data structure
345  * and how it is filled with data is discussed with the aead_request_*
346  * functions.
347  *
348  * IMPORTANT NOTE The encryption operation creates the authentication data /
349  *		  tag. That data is concatenated with the created ciphertext.
350  *		  The ciphertext memory size is therefore the given number of
351  *		  block cipher blocks + the size defined by the
352  *		  crypto_aead_setauthsize invocation. The caller must ensure
353  *		  that sufficient memory is available for the ciphertext and
354  *		  the authentication tag.
355  *
356  * Return: 0 if the cipher operation was successful; < 0 if an error occurred
357  */
358 int crypto_aead_encrypt(struct aead_request *req);
359 
360 /**
361  * crypto_aead_decrypt() - decrypt ciphertext
362  * @req: reference to the aead_request handle that holds all information
363  *	 needed to perform the cipher operation
364  *
365  * Decrypt ciphertext 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 caller must concatenate the ciphertext followed by the
370  *		  authentication data / tag. That authentication data / tag
371  *		  must have the size defined by the crypto_aead_setauthsize
372  *		  invocation.
373  *
374  *
375  * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
376  *	   cipher operation performs the authentication of the data during the
377  *	   decryption operation. Therefore, the function returns this error if
378  *	   the authentication of the ciphertext was unsuccessful (i.e. the
379  *	   integrity of the ciphertext or the associated data was violated);
380  *	   < 0 if an error occurred.
381  */
382 int crypto_aead_decrypt(struct aead_request *req);
383 
384 /**
385  * DOC: Asynchronous AEAD Request Handle
386  *
387  * The aead_request data structure contains all pointers to data required for
388  * the AEAD cipher operation. This includes the cipher handle (which can be
389  * used by multiple aead_request instances), pointer to plaintext and
390  * ciphertext, asynchronous callback function, etc. It acts as a handle to the
391  * aead_request_* API calls in a similar way as AEAD handle to the
392  * crypto_aead_* API calls.
393  */
394 
395 /**
396  * crypto_aead_reqsize() - obtain size of the request data structure
397  * @tfm: cipher handle
398  *
399  * Return: number of bytes
400  */
crypto_aead_reqsize(struct crypto_aead * tfm)401 static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)
402 {
403 	return tfm->reqsize;
404 }
405 
406 /**
407  * aead_request_set_tfm() - update cipher handle reference in request
408  * @req: request handle to be modified
409  * @tfm: cipher handle that shall be added to the request handle
410  *
411  * Allow the caller to replace the existing aead handle in the request
412  * data structure with a different one.
413  */
aead_request_set_tfm(struct aead_request * req,struct crypto_aead * tfm)414 static inline void aead_request_set_tfm(struct aead_request *req,
415 					struct crypto_aead *tfm)
416 {
417 	req->base.tfm = crypto_aead_tfm(tfm);
418 }
419 
420 /**
421  * aead_request_alloc() - allocate request data structure
422  * @tfm: cipher handle to be registered with the request
423  * @gfp: memory allocation flag that is handed to kmalloc by the API call.
424  *
425  * Allocate the request data structure that must be used with the AEAD
426  * encrypt and decrypt API calls. During the allocation, the provided aead
427  * handle is registered in the request data structure.
428  *
429  * Return: allocated request handle in case of success, or NULL if out of memory
430  */
aead_request_alloc(struct crypto_aead * tfm,gfp_t gfp)431 static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
432 						      gfp_t gfp)
433 {
434 	struct aead_request *req;
435 
436 	req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);
437 
438 	if (likely(req))
439 		aead_request_set_tfm(req, tfm);
440 
441 	return req;
442 }
443 
444 /**
445  * aead_request_free() - zeroize and free request data structure
446  * @req: request data structure cipher handle to be freed
447  */
aead_request_free(struct aead_request * req)448 static inline void aead_request_free(struct aead_request *req)
449 {
450 	kfree_sensitive(req);
451 }
452 
453 /**
454  * aead_request_set_callback() - set asynchronous callback function
455  * @req: request handle
456  * @flags: specify zero or an ORing of the flags
457  *	   CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
458  *	   increase the wait queue beyond the initial maximum size;
459  *	   CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
460  * @compl: callback function pointer to be registered with the request handle
461  * @data: The data pointer refers to memory that is not used by the kernel
462  *	  crypto API, but provided to the callback function for it to use. Here,
463  *	  the caller can provide a reference to memory the callback function can
464  *	  operate on. As the callback function is invoked asynchronously to the
465  *	  related functionality, it may need to access data structures of the
466  *	  related functionality which can be referenced using this pointer. The
467  *	  callback function can access the memory via the "data" field in the
468  *	  crypto_async_request data structure provided to the callback function.
469  *
470  * Setting the callback function that is triggered once the cipher operation
471  * completes
472  *
473  * The callback function is registered with the aead_request handle and
474  * must comply with the following template::
475  *
476  *	void callback_function(struct crypto_async_request *req, int error)
477  */
aead_request_set_callback(struct aead_request * req,u32 flags,crypto_completion_t compl,void * data)478 static inline void aead_request_set_callback(struct aead_request *req,
479 					     u32 flags,
480 					     crypto_completion_t compl,
481 					     void *data)
482 {
483 	req->base.complete = compl;
484 	req->base.data = data;
485 	req->base.flags = flags;
486 }
487 
488 /**
489  * aead_request_set_crypt - set data buffers
490  * @req: request handle
491  * @src: source scatter / gather list
492  * @dst: destination scatter / gather list
493  * @cryptlen: number of bytes to process from @src
494  * @iv: IV for the cipher operation which must comply with the IV size defined
495  *      by crypto_aead_ivsize()
496  *
497  * Setting the source data and destination data scatter / gather lists which
498  * hold the associated data concatenated with the plaintext or ciphertext. See
499  * below for the authentication tag.
500  *
501  * For encryption, the source is treated as the plaintext and the
502  * destination is the ciphertext. For a decryption operation, the use is
503  * reversed - the source is the ciphertext and the destination is the plaintext.
504  *
505  * The memory structure for cipher operation has the following structure:
506  *
507  * - AEAD encryption input:  assoc data || plaintext
508  * - AEAD encryption output: assoc data || ciphertext || auth tag
509  * - AEAD decryption input:  assoc data || ciphertext || auth tag
510  * - AEAD decryption output: assoc data || plaintext
511  *
512  * Albeit the kernel requires the presence of the AAD buffer, however,
513  * the kernel does not fill the AAD buffer in the output case. If the
514  * caller wants to have that data buffer filled, the caller must either
515  * use an in-place cipher operation (i.e. same memory location for
516  * input/output memory location).
517  */
aead_request_set_crypt(struct aead_request * req,struct scatterlist * src,struct scatterlist * dst,unsigned int cryptlen,u8 * iv)518 static inline void aead_request_set_crypt(struct aead_request *req,
519 					  struct scatterlist *src,
520 					  struct scatterlist *dst,
521 					  unsigned int cryptlen, u8 *iv)
522 {
523 	req->src = src;
524 	req->dst = dst;
525 	req->cryptlen = cryptlen;
526 	req->iv = iv;
527 }
528 
529 /**
530  * aead_request_set_ad - set associated data information
531  * @req: request handle
532  * @assoclen: number of bytes in associated data
533  *
534  * Setting the AD information.  This function sets the length of
535  * the associated data.
536  */
aead_request_set_ad(struct aead_request * req,unsigned int assoclen)537 static inline void aead_request_set_ad(struct aead_request *req,
538 				       unsigned int assoclen)
539 {
540 	req->assoclen = assoclen;
541 }
542 
543 #endif	/* _CRYPTO_AEAD_H */
544