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