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TOMOYO Linux Cross Reference
Linux/include/crypto/aead.h

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  1 /*
  2  * AEAD: Authenticated Encryption with Associated Data
  3  * 
  4  * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
  5  *
  6  * This program is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License as published by the Free
  8  * Software Foundation; either version 2 of the License, or (at your option) 
  9  * any later version.
 10  *
 11  */
 12 
 13 #ifndef _CRYPTO_AEAD_H
 14 #define _CRYPTO_AEAD_H
 15 
 16 #include <linux/crypto.h>
 17 #include <linux/kernel.h>
 18 #include <linux/slab.h>
 19 
 20 /**
 21  * DOC: Authenticated Encryption With Associated Data (AEAD) Cipher API
 22  *
 23  * The AEAD cipher API is used with the ciphers of type CRYPTO_ALG_TYPE_AEAD
 24  * (listed as type "aead" in /proc/crypto)
 25  *
 26  * The most prominent examples for this type of encryption is GCM and CCM.
 27  * However, the kernel supports other types of AEAD ciphers which are defined
 28  * with the following cipher string:
 29  *
 30  *      authenc(keyed message digest, block cipher)
 31  *
 32  * For example: authenc(hmac(sha256), cbc(aes))
 33  *
 34  * The example code provided for the symmetric key cipher operation
 35  * applies here as well. Naturally all *skcipher* symbols must be exchanged
 36  * the *aead* pendants discussed in the following. In addition, for the AEAD
 37  * operation, the aead_request_set_ad function must be used to set the
 38  * pointer to the associated data memory location before performing the
 39  * encryption or decryption operation. In case of an encryption, the associated
 40  * data memory is filled during the encryption operation. For decryption, the
 41  * associated data memory must contain data that is used to verify the integrity
 42  * of the decrypted data. Another deviation from the asynchronous block cipher
 43  * operation is that the caller should explicitly check for -EBADMSG of the
 44  * crypto_aead_decrypt. That error indicates an authentication error, i.e.
 45  * a breach in the integrity of the message. In essence, that -EBADMSG error
 46  * code is the key bonus an AEAD cipher has over "standard" block chaining
 47  * modes.
 48  *
 49  * Memory Structure:
 50  *
 51  * To support the needs of the most prominent user of AEAD ciphers, namely
 52  * IPSEC, the AEAD ciphers have a special memory layout the caller must adhere
 53  * to.
 54  *
 55  * The scatter list pointing to the input data must contain:
 56  *
 57  * * for RFC4106 ciphers, the concatenation of
 58  *   associated authentication data || IV || plaintext or ciphertext. Note, the
 59  *   same IV (buffer) is also set with the aead_request_set_crypt call. Note,
 60  *   the API call of aead_request_set_ad must provide the length of the AAD and
 61  *   the IV. The API call of aead_request_set_crypt only points to the size of
 62  *   the input plaintext or ciphertext.
 63  *
 64  * * for "normal" AEAD ciphers, the concatenation of
 65  *   associated authentication data || plaintext or ciphertext.
 66  *
 67  * It is important to note that if multiple scatter gather list entries form
 68  * the input data mentioned above, the first entry must not point to a NULL
 69  * buffer. If there is any potential where the AAD buffer can be NULL, the
 70  * calling code must contain a precaution to ensure that this does not result
 71  * in the first scatter gather list entry pointing to a NULL buffer.
 72  */
 73 
 74 struct crypto_aead;
 75 
 76 /**
 77  *      struct aead_request - AEAD request
 78  *      @base: Common attributes for async crypto requests
 79  *      @assoclen: Length in bytes of associated data for authentication
 80  *      @cryptlen: Length of data to be encrypted or decrypted
 81  *      @iv: Initialisation vector
 82  *      @src: Source data
 83  *      @dst: Destination data
 84  *      @__ctx: Start of private context data
 85  */
 86 struct aead_request {
 87         struct crypto_async_request base;
 88 
 89         unsigned int assoclen;
 90         unsigned int cryptlen;
 91 
 92         u8 *iv;
 93 
 94         struct scatterlist *src;
 95         struct scatterlist *dst;
 96 
 97         void *__ctx[] CRYPTO_MINALIGN_ATTR;
 98 };
 99 
100 /**
101  * struct aead_alg - AEAD cipher definition
102  * @maxauthsize: Set the maximum authentication tag size supported by the
103  *               transformation. A transformation may support smaller tag sizes.
104  *               As the authentication tag is a message digest to ensure the
105  *               integrity of the encrypted data, a consumer typically wants the
106  *               largest authentication tag possible as defined by this
107  *               variable.
108  * @setauthsize: Set authentication size for the AEAD transformation. This
109  *               function is used to specify the consumer requested size of the
110  *               authentication tag to be either generated by the transformation
111  *               during encryption or the size of the authentication tag to be
112  *               supplied during the decryption operation. This function is also
113  *               responsible for checking the authentication tag size for
114  *               validity.
115  * @setkey: see struct skcipher_alg
116  * @encrypt: see struct skcipher_alg
117  * @decrypt: see struct skcipher_alg
118  * @geniv: 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         const char *geniv;
146 
147         unsigned int ivsize;
148         unsigned int maxauthsize;
149         unsigned int chunksize;
150 
151         struct crypto_alg base;
152 };
153 
154 struct crypto_aead {
155         unsigned int authsize;
156         unsigned int reqsize;
157 
158         struct crypto_tfm base;
159 };
160 
161 static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
162 {
163         return container_of(tfm, struct crypto_aead, base);
164 }
165 
166 /**
167  * crypto_alloc_aead() - allocate AEAD cipher handle
168  * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
169  *           AEAD cipher
170  * @type: specifies the type of the cipher
171  * @mask: specifies the mask for the cipher
172  *
173  * Allocate a cipher handle for an AEAD. The returned struct
174  * crypto_aead is the cipher handle that is required for any subsequent
175  * API invocation for that AEAD.
176  *
177  * Return: allocated cipher handle in case of success; IS_ERR() is true in case
178  *         of an error, PTR_ERR() returns the error code.
179  */
180 struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);
181 
182 static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
183 {
184         return &tfm->base;
185 }
186 
187 /**
188  * crypto_free_aead() - zeroize and free aead handle
189  * @tfm: cipher handle to be freed
190  */
191 static inline void crypto_free_aead(struct crypto_aead *tfm)
192 {
193         crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
194 }
195 
196 static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
197 {
198         return container_of(crypto_aead_tfm(tfm)->__crt_alg,
199                             struct aead_alg, base);
200 }
201 
202 static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
203 {
204         return alg->ivsize;
205 }
206 
207 /**
208  * crypto_aead_ivsize() - obtain IV size
209  * @tfm: cipher handle
210  *
211  * The size of the IV for the aead referenced by the cipher handle is
212  * returned. This IV size may be zero if the cipher does not need an IV.
213  *
214  * Return: IV size in bytes
215  */
216 static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)
217 {
218         return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
219 }
220 
221 /**
222  * crypto_aead_authsize() - obtain maximum authentication data size
223  * @tfm: cipher handle
224  *
225  * The maximum size of the authentication data for the AEAD cipher referenced
226  * by the AEAD cipher handle is returned. The authentication data size may be
227  * zero if the cipher implements a hard-coded maximum.
228  *
229  * The authentication data may also be known as "tag value".
230  *
231  * Return: authentication data size / tag size in bytes
232  */
233 static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)
234 {
235         return tfm->authsize;
236 }
237 
238 /**
239  * crypto_aead_blocksize() - obtain block size of cipher
240  * @tfm: cipher handle
241  *
242  * The block size for the AEAD referenced with the cipher handle is returned.
243  * The caller may use that information to allocate appropriate memory for the
244  * data returned by the encryption or decryption operation
245  *
246  * Return: block size of cipher
247  */
248 static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
249 {
250         return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
251 }
252 
253 static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
254 {
255         return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));
256 }
257 
258 static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)
259 {
260         return crypto_tfm_get_flags(crypto_aead_tfm(tfm));
261 }
262 
263 static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)
264 {
265         crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);
266 }
267 
268 static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)
269 {
270         crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
271 }
272 
273 /**
274  * crypto_aead_setkey() - set key for cipher
275  * @tfm: cipher handle
276  * @key: buffer holding the key
277  * @keylen: length of the key in bytes
278  *
279  * The caller provided key is set for the AEAD referenced by the cipher
280  * handle.
281  *
282  * Note, the key length determines the cipher type. Many block ciphers implement
283  * different cipher modes depending on the key size, such as AES-128 vs AES-192
284  * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
285  * is performed.
286  *
287  * Return: 0 if the setting of the key was successful; < 0 if an error occurred
288  */
289 int crypto_aead_setkey(struct crypto_aead *tfm,
290                        const u8 *key, unsigned int keylen);
291 
292 /**
293  * crypto_aead_setauthsize() - set authentication data size
294  * @tfm: cipher handle
295  * @authsize: size of the authentication data / tag in bytes
296  *
297  * Set the authentication data size / tag size. AEAD requires an authentication
298  * tag (or MAC) in addition to the associated data.
299  *
300  * Return: 0 if the setting of the key was successful; < 0 if an error occurred
301  */
302 int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);
303 
304 static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
305 {
306         return __crypto_aead_cast(req->base.tfm);
307 }
308 
309 /**
310  * crypto_aead_encrypt() - encrypt plaintext
311  * @req: reference to the aead_request handle that holds all information
312  *       needed to perform the cipher operation
313  *
314  * Encrypt plaintext data using the aead_request handle. That data structure
315  * and how it is filled with data is discussed with the aead_request_*
316  * functions.
317  *
318  * IMPORTANT NOTE The encryption operation creates the authentication data /
319  *                tag. That data is concatenated with the created ciphertext.
320  *                The ciphertext memory size is therefore the given number of
321  *                block cipher blocks + the size defined by the
322  *                crypto_aead_setauthsize invocation. The caller must ensure
323  *                that sufficient memory is available for the ciphertext and
324  *                the authentication tag.
325  *
326  * Return: 0 if the cipher operation was successful; < 0 if an error occurred
327  */
328 static inline int crypto_aead_encrypt(struct aead_request *req)
329 {
330         struct crypto_aead *aead = crypto_aead_reqtfm(req);
331 
332         if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
333                 return -ENOKEY;
334 
335         return crypto_aead_alg(aead)->encrypt(req);
336 }
337 
338 /**
339  * crypto_aead_decrypt() - decrypt ciphertext
340  * @req: reference to the ablkcipher_request handle that holds all information
341  *       needed to perform the cipher operation
342  *
343  * Decrypt ciphertext data using the aead_request handle. That data structure
344  * and how it is filled with data is discussed with the aead_request_*
345  * functions.
346  *
347  * IMPORTANT NOTE The caller must concatenate the ciphertext followed by the
348  *                authentication data / tag. That authentication data / tag
349  *                must have the size defined by the crypto_aead_setauthsize
350  *                invocation.
351  *
352  *
353  * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
354  *         cipher operation performs the authentication of the data during the
355  *         decryption operation. Therefore, the function returns this error if
356  *         the authentication of the ciphertext was unsuccessful (i.e. the
357  *         integrity of the ciphertext or the associated data was violated);
358  *         < 0 if an error occurred.
359  */
360 static inline int crypto_aead_decrypt(struct aead_request *req)
361 {
362         struct crypto_aead *aead = crypto_aead_reqtfm(req);
363 
364         if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
365                 return -ENOKEY;
366 
367         if (req->cryptlen < crypto_aead_authsize(aead))
368                 return -EINVAL;
369 
370         return crypto_aead_alg(aead)->decrypt(req);
371 }
372 
373 /**
374  * DOC: Asynchronous AEAD Request Handle
375  *
376  * The aead_request data structure contains all pointers to data required for
377  * the AEAD cipher operation. This includes the cipher handle (which can be
378  * used by multiple aead_request instances), pointer to plaintext and
379  * ciphertext, asynchronous callback function, etc. It acts as a handle to the
380  * aead_request_* API calls in a similar way as AEAD handle to the
381  * crypto_aead_* API calls.
382  */
383 
384 /**
385  * crypto_aead_reqsize() - obtain size of the request data structure
386  * @tfm: cipher handle
387  *
388  * Return: number of bytes
389  */
390 static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)
391 {
392         return tfm->reqsize;
393 }
394 
395 /**
396  * aead_request_set_tfm() - update cipher handle reference in request
397  * @req: request handle to be modified
398  * @tfm: cipher handle that shall be added to the request handle
399  *
400  * Allow the caller to replace the existing aead handle in the request
401  * data structure with a different one.
402  */
403 static inline void aead_request_set_tfm(struct aead_request *req,
404                                         struct crypto_aead *tfm)
405 {
406         req->base.tfm = crypto_aead_tfm(tfm);
407 }
408 
409 /**
410  * aead_request_alloc() - allocate request data structure
411  * @tfm: cipher handle to be registered with the request
412  * @gfp: memory allocation flag that is handed to kmalloc by the API call.
413  *
414  * Allocate the request data structure that must be used with the AEAD
415  * encrypt and decrypt API calls. During the allocation, the provided aead
416  * handle is registered in the request data structure.
417  *
418  * Return: allocated request handle in case of success, or NULL if out of memory
419  */
420 static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
421                                                       gfp_t gfp)
422 {
423         struct aead_request *req;
424 
425         req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);
426 
427         if (likely(req))
428                 aead_request_set_tfm(req, tfm);
429 
430         return req;
431 }
432 
433 /**
434  * aead_request_free() - zeroize and free request data structure
435  * @req: request data structure cipher handle to be freed
436  */
437 static inline void aead_request_free(struct aead_request *req)
438 {
439         kzfree(req);
440 }
441 
442 /**
443  * aead_request_set_callback() - set asynchronous callback function
444  * @req: request handle
445  * @flags: specify zero or an ORing of the flags
446  *         CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
447  *         increase the wait queue beyond the initial maximum size;
448  *         CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
449  * @compl: callback function pointer to be registered with the request handle
450  * @data: The data pointer refers to memory that is not used by the kernel
451  *        crypto API, but provided to the callback function for it to use. Here,
452  *        the caller can provide a reference to memory the callback function can
453  *        operate on. As the callback function is invoked asynchronously to the
454  *        related functionality, it may need to access data structures of the
455  *        related functionality which can be referenced using this pointer. The
456  *        callback function can access the memory via the "data" field in the
457  *        crypto_async_request data structure provided to the callback function.
458  *
459  * Setting the callback function that is triggered once the cipher operation
460  * completes
461  *
462  * The callback function is registered with the aead_request handle and
463  * must comply with the following template::
464  *
465  *      void callback_function(struct crypto_async_request *req, int error)
466  */
467 static inline void aead_request_set_callback(struct aead_request *req,
468                                              u32 flags,
469                                              crypto_completion_t compl,
470                                              void *data)
471 {
472         req->base.complete = compl;
473         req->base.data = data;
474         req->base.flags = flags;
475 }
476 
477 /**
478  * aead_request_set_crypt - set data buffers
479  * @req: request handle
480  * @src: source scatter / gather list
481  * @dst: destination scatter / gather list
482  * @cryptlen: number of bytes to process from @src
483  * @iv: IV for the cipher operation which must comply with the IV size defined
484  *      by crypto_aead_ivsize()
485  *
486  * Setting the source data and destination data scatter / gather lists which
487  * hold the associated data concatenated with the plaintext or ciphertext. See
488  * below for the authentication tag.
489  *
490  * For encryption, the source is treated as the plaintext and the
491  * destination is the ciphertext. For a decryption operation, the use is
492  * reversed - the source is the ciphertext and the destination is the plaintext.
493  *
494  * The memory structure for cipher operation has the following structure:
495  *
496  * - AEAD encryption input:  assoc data || plaintext
497  * - AEAD encryption output: assoc data || cipherntext || auth tag
498  * - AEAD decryption input:  assoc data || ciphertext || auth tag
499  * - AEAD decryption output: assoc data || plaintext
500  *
501  * Albeit the kernel requires the presence of the AAD buffer, however,
502  * the kernel does not fill the AAD buffer in the output case. If the
503  * caller wants to have that data buffer filled, the caller must either
504  * use an in-place cipher operation (i.e. same memory location for
505  * input/output memory location).
506  */
507 static inline void aead_request_set_crypt(struct aead_request *req,
508                                           struct scatterlist *src,
509                                           struct scatterlist *dst,
510                                           unsigned int cryptlen, u8 *iv)
511 {
512         req->src = src;
513         req->dst = dst;
514         req->cryptlen = cryptlen;
515         req->iv = iv;
516 }
517 
518 /**
519  * aead_request_set_ad - set associated data information
520  * @req: request handle
521  * @assoclen: number of bytes in associated data
522  *
523  * Setting the AD information.  This function sets the length of
524  * the associated data.
525  */
526 static inline void aead_request_set_ad(struct aead_request *req,
527                                        unsigned int assoclen)
528 {
529         req->assoclen = assoclen;
530 }
531 
532 #endif  /* _CRYPTO_AEAD_H */
533 

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