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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         return crypto_aead_alg(crypto_aead_reqtfm(req))->encrypt(req);
331 }
332 
333 /**
334  * crypto_aead_decrypt() - decrypt ciphertext
335  * @req: reference to the ablkcipher_request handle that holds all information
336  *       needed to perform the cipher operation
337  *
338  * Decrypt ciphertext data using the aead_request handle. That data structure
339  * and how it is filled with data is discussed with the aead_request_*
340  * functions.
341  *
342  * IMPORTANT NOTE The caller must concatenate the ciphertext followed by the
343  *                authentication data / tag. That authentication data / tag
344  *                must have the size defined by the crypto_aead_setauthsize
345  *                invocation.
346  *
347  *
348  * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
349  *         cipher operation performs the authentication of the data during the
350  *         decryption operation. Therefore, the function returns this error if
351  *         the authentication of the ciphertext was unsuccessful (i.e. the
352  *         integrity of the ciphertext or the associated data was violated);
353  *         < 0 if an error occurred.
354  */
355 static inline int crypto_aead_decrypt(struct aead_request *req)
356 {
357         struct crypto_aead *aead = crypto_aead_reqtfm(req);
358 
359         if (req->cryptlen < crypto_aead_authsize(aead))
360                 return -EINVAL;
361 
362         return crypto_aead_alg(aead)->decrypt(req);
363 }
364 
365 /**
366  * DOC: Asynchronous AEAD Request Handle
367  *
368  * The aead_request data structure contains all pointers to data required for
369  * the AEAD cipher operation. This includes the cipher handle (which can be
370  * used by multiple aead_request instances), pointer to plaintext and
371  * ciphertext, asynchronous callback function, etc. It acts as a handle to the
372  * aead_request_* API calls in a similar way as AEAD handle to the
373  * crypto_aead_* API calls.
374  */
375 
376 /**
377  * crypto_aead_reqsize() - obtain size of the request data structure
378  * @tfm: cipher handle
379  *
380  * Return: number of bytes
381  */
382 static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)
383 {
384         return tfm->reqsize;
385 }
386 
387 /**
388  * aead_request_set_tfm() - update cipher handle reference in request
389  * @req: request handle to be modified
390  * @tfm: cipher handle that shall be added to the request handle
391  *
392  * Allow the caller to replace the existing aead handle in the request
393  * data structure with a different one.
394  */
395 static inline void aead_request_set_tfm(struct aead_request *req,
396                                         struct crypto_aead *tfm)
397 {
398         req->base.tfm = crypto_aead_tfm(tfm);
399 }
400 
401 /**
402  * aead_request_alloc() - allocate request data structure
403  * @tfm: cipher handle to be registered with the request
404  * @gfp: memory allocation flag that is handed to kmalloc by the API call.
405  *
406  * Allocate the request data structure that must be used with the AEAD
407  * encrypt and decrypt API calls. During the allocation, the provided aead
408  * handle is registered in the request data structure.
409  *
410  * Return: allocated request handle in case of success, or NULL if out of memory
411  */
412 static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
413                                                       gfp_t gfp)
414 {
415         struct aead_request *req;
416 
417         req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);
418 
419         if (likely(req))
420                 aead_request_set_tfm(req, tfm);
421 
422         return req;
423 }
424 
425 /**
426  * aead_request_free() - zeroize and free request data structure
427  * @req: request data structure cipher handle to be freed
428  */
429 static inline void aead_request_free(struct aead_request *req)
430 {
431         kzfree(req);
432 }
433 
434 /**
435  * aead_request_set_callback() - set asynchronous callback function
436  * @req: request handle
437  * @flags: specify zero or an ORing of the flags
438  *         CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
439  *         increase the wait queue beyond the initial maximum size;
440  *         CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
441  * @compl: callback function pointer to be registered with the request handle
442  * @data: The data pointer refers to memory that is not used by the kernel
443  *        crypto API, but provided to the callback function for it to use. Here,
444  *        the caller can provide a reference to memory the callback function can
445  *        operate on. As the callback function is invoked asynchronously to the
446  *        related functionality, it may need to access data structures of the
447  *        related functionality which can be referenced using this pointer. The
448  *        callback function can access the memory via the "data" field in the
449  *        crypto_async_request data structure provided to the callback function.
450  *
451  * Setting the callback function that is triggered once the cipher operation
452  * completes
453  *
454  * The callback function is registered with the aead_request handle and
455  * must comply with the following template::
456  *
457  *      void callback_function(struct crypto_async_request *req, int error)
458  */
459 static inline void aead_request_set_callback(struct aead_request *req,
460                                              u32 flags,
461                                              crypto_completion_t compl,
462                                              void *data)
463 {
464         req->base.complete = compl;
465         req->base.data = data;
466         req->base.flags = flags;
467 }
468 
469 /**
470  * aead_request_set_crypt - set data buffers
471  * @req: request handle
472  * @src: source scatter / gather list
473  * @dst: destination scatter / gather list
474  * @cryptlen: number of bytes to process from @src
475  * @iv: IV for the cipher operation which must comply with the IV size defined
476  *      by crypto_aead_ivsize()
477  *
478  * Setting the source data and destination data scatter / gather lists which
479  * hold the associated data concatenated with the plaintext or ciphertext. See
480  * below for the authentication tag.
481  *
482  * For encryption, the source is treated as the plaintext and the
483  * destination is the ciphertext. For a decryption operation, the use is
484  * reversed - the source is the ciphertext and the destination is the plaintext.
485  *
486  * The memory structure for cipher operation has the following structure:
487  *
488  * - AEAD encryption input:  assoc data || plaintext
489  * - AEAD encryption output: assoc data || cipherntext || auth tag
490  * - AEAD decryption input:  assoc data || ciphertext || auth tag
491  * - AEAD decryption output: assoc data || plaintext
492  *
493  * Albeit the kernel requires the presence of the AAD buffer, however,
494  * the kernel does not fill the AAD buffer in the output case. If the
495  * caller wants to have that data buffer filled, the caller must either
496  * use an in-place cipher operation (i.e. same memory location for
497  * input/output memory location).
498  */
499 static inline void aead_request_set_crypt(struct aead_request *req,
500                                           struct scatterlist *src,
501                                           struct scatterlist *dst,
502                                           unsigned int cryptlen, u8 *iv)
503 {
504         req->src = src;
505         req->dst = dst;
506         req->cryptlen = cryptlen;
507         req->iv = iv;
508 }
509 
510 /**
511  * aead_request_set_ad - set associated data information
512  * @req: request handle
513  * @assoclen: number of bytes in associated data
514  *
515  * Setting the AD information.  This function sets the length of
516  * the associated data.
517  */
518 static inline void aead_request_set_ad(struct aead_request *req,
519                                        unsigned int assoclen)
520 {
521         req->assoclen = assoclen;
522 }
523 
524 #endif  /* _CRYPTO_AEAD_H */
525 

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