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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  * @ivsize: see struct skcipher_alg
119  * @chunksize: see struct skcipher_alg
120  * @init: Initialize the cryptographic transformation object. This function
121  *        is used to initialize the cryptographic transformation object.
122  *        This function is called only once at the instantiation time, right
123  *        after the transformation context was allocated. In case the
124  *        cryptographic hardware has some special requirements which need to
125  *        be handled by software, this function shall check for the precise
126  *        requirement of the transformation and put any software fallbacks
127  *        in place.
128  * @exit: Deinitialize the cryptographic transformation object. This is a
129  *        counterpart to @init, used to remove various changes set in
130  *        @init.
131  * @base: Definition of a generic crypto cipher algorithm.
132  *
133  * All fields except @ivsize is mandatory and must be filled.
134  */
135 struct aead_alg {
136         int (*setkey)(struct crypto_aead *tfm, const u8 *key,
137                       unsigned int keylen);
138         int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize);
139         int (*encrypt)(struct aead_request *req);
140         int (*decrypt)(struct aead_request *req);
141         int (*init)(struct crypto_aead *tfm);
142         void (*exit)(struct crypto_aead *tfm);
143 
144         unsigned int ivsize;
145         unsigned int maxauthsize;
146         unsigned int chunksize;
147 
148         struct crypto_alg base;
149 };
150 
151 struct crypto_aead {
152         unsigned int authsize;
153         unsigned int reqsize;
154 
155         struct crypto_tfm base;
156 };
157 
158 static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
159 {
160         return container_of(tfm, struct crypto_aead, base);
161 }
162 
163 /**
164  * crypto_alloc_aead() - allocate AEAD cipher handle
165  * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
166  *           AEAD cipher
167  * @type: specifies the type of the cipher
168  * @mask: specifies the mask for the cipher
169  *
170  * Allocate a cipher handle for an AEAD. The returned struct
171  * crypto_aead is the cipher handle that is required for any subsequent
172  * API invocation for that AEAD.
173  *
174  * Return: allocated cipher handle in case of success; IS_ERR() is true in case
175  *         of an error, PTR_ERR() returns the error code.
176  */
177 struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);
178 
179 static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
180 {
181         return &tfm->base;
182 }
183 
184 /**
185  * crypto_free_aead() - zeroize and free aead handle
186  * @tfm: cipher handle to be freed
187  */
188 static inline void crypto_free_aead(struct crypto_aead *tfm)
189 {
190         crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
191 }
192 
193 static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
194 {
195         return container_of(crypto_aead_tfm(tfm)->__crt_alg,
196                             struct aead_alg, base);
197 }
198 
199 static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
200 {
201         return alg->ivsize;
202 }
203 
204 /**
205  * crypto_aead_ivsize() - obtain IV size
206  * @tfm: cipher handle
207  *
208  * The size of the IV for the aead referenced by the cipher handle is
209  * returned. This IV size may be zero if the cipher does not need an IV.
210  *
211  * Return: IV size in bytes
212  */
213 static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)
214 {
215         return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
216 }
217 
218 /**
219  * crypto_aead_authsize() - obtain maximum authentication data size
220  * @tfm: cipher handle
221  *
222  * The maximum size of the authentication data for the AEAD cipher referenced
223  * by the AEAD cipher handle is returned. The authentication data size may be
224  * zero if the cipher implements a hard-coded maximum.
225  *
226  * The authentication data may also be known as "tag value".
227  *
228  * Return: authentication data size / tag size in bytes
229  */
230 static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)
231 {
232         return tfm->authsize;
233 }
234 
235 /**
236  * crypto_aead_blocksize() - obtain block size of cipher
237  * @tfm: cipher handle
238  *
239  * The block size for the AEAD referenced with the cipher handle is returned.
240  * The caller may use that information to allocate appropriate memory for the
241  * data returned by the encryption or decryption operation
242  *
243  * Return: block size of cipher
244  */
245 static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
246 {
247         return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
248 }
249 
250 static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
251 {
252         return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));
253 }
254 
255 static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)
256 {
257         return crypto_tfm_get_flags(crypto_aead_tfm(tfm));
258 }
259 
260 static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)
261 {
262         crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);
263 }
264 
265 static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)
266 {
267         crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
268 }
269 
270 /**
271  * crypto_aead_setkey() - set key for cipher
272  * @tfm: cipher handle
273  * @key: buffer holding the key
274  * @keylen: length of the key in bytes
275  *
276  * The caller provided key is set for the AEAD referenced by the cipher
277  * handle.
278  *
279  * Note, the key length determines the cipher type. Many block ciphers implement
280  * different cipher modes depending on the key size, such as AES-128 vs AES-192
281  * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
282  * is performed.
283  *
284  * Return: 0 if the setting of the key was successful; < 0 if an error occurred
285  */
286 int crypto_aead_setkey(struct crypto_aead *tfm,
287                        const u8 *key, unsigned int keylen);
288 
289 /**
290  * crypto_aead_setauthsize() - set authentication data size
291  * @tfm: cipher handle
292  * @authsize: size of the authentication data / tag in bytes
293  *
294  * Set the authentication data size / tag size. AEAD requires an authentication
295  * tag (or MAC) in addition to the associated data.
296  *
297  * Return: 0 if the setting of the key was successful; < 0 if an error occurred
298  */
299 int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);
300 
301 static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
302 {
303         return __crypto_aead_cast(req->base.tfm);
304 }
305 
306 /**
307  * crypto_aead_encrypt() - encrypt plaintext
308  * @req: reference to the aead_request handle that holds all information
309  *       needed to perform the cipher operation
310  *
311  * Encrypt plaintext data using the aead_request handle. That data structure
312  * and how it is filled with data is discussed with the aead_request_*
313  * functions.
314  *
315  * IMPORTANT NOTE The encryption operation creates the authentication data /
316  *                tag. That data is concatenated with the created ciphertext.
317  *                The ciphertext memory size is therefore the given number of
318  *                block cipher blocks + the size defined by the
319  *                crypto_aead_setauthsize invocation. The caller must ensure
320  *                that sufficient memory is available for the ciphertext and
321  *                the authentication tag.
322  *
323  * Return: 0 if the cipher operation was successful; < 0 if an error occurred
324  */
325 static inline int crypto_aead_encrypt(struct aead_request *req)
326 {
327         struct crypto_aead *aead = crypto_aead_reqtfm(req);
328         struct crypto_alg *alg = aead->base.__crt_alg;
329         unsigned int cryptlen = req->cryptlen;
330         int ret;
331 
332         crypto_stats_get(alg);
333         if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
334                 ret = -ENOKEY;
335         else
336                 ret = crypto_aead_alg(aead)->encrypt(req);
337         crypto_stats_aead_encrypt(cryptlen, alg, ret);
338         return ret;
339 }
340 
341 /**
342  * crypto_aead_decrypt() - decrypt ciphertext
343  * @req: reference to the ablkcipher_request handle that holds all information
344  *       needed to perform the cipher operation
345  *
346  * Decrypt ciphertext data using the aead_request handle. That data structure
347  * and how it is filled with data is discussed with the aead_request_*
348  * functions.
349  *
350  * IMPORTANT NOTE The caller must concatenate the ciphertext followed by the
351  *                authentication data / tag. That authentication data / tag
352  *                must have the size defined by the crypto_aead_setauthsize
353  *                invocation.
354  *
355  *
356  * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
357  *         cipher operation performs the authentication of the data during the
358  *         decryption operation. Therefore, the function returns this error if
359  *         the authentication of the ciphertext was unsuccessful (i.e. the
360  *         integrity of the ciphertext or the associated data was violated);
361  *         < 0 if an error occurred.
362  */
363 static inline int crypto_aead_decrypt(struct aead_request *req)
364 {
365         struct crypto_aead *aead = crypto_aead_reqtfm(req);
366         struct crypto_alg *alg = aead->base.__crt_alg;
367         unsigned int cryptlen = req->cryptlen;
368         int ret;
369 
370         crypto_stats_get(alg);
371         if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
372                 ret = -ENOKEY;
373         else if (req->cryptlen < crypto_aead_authsize(aead))
374                 ret = -EINVAL;
375         else
376                 ret = crypto_aead_alg(aead)->decrypt(req);
377         crypto_stats_aead_decrypt(cryptlen, alg, ret);
378         return ret;
379 }
380 
381 /**
382  * DOC: Asynchronous AEAD Request Handle
383  *
384  * The aead_request data structure contains all pointers to data required for
385  * the AEAD cipher operation. This includes the cipher handle (which can be
386  * used by multiple aead_request instances), pointer to plaintext and
387  * ciphertext, asynchronous callback function, etc. It acts as a handle to the
388  * aead_request_* API calls in a similar way as AEAD handle to the
389  * crypto_aead_* API calls.
390  */
391 
392 /**
393  * crypto_aead_reqsize() - obtain size of the request data structure
394  * @tfm: cipher handle
395  *
396  * Return: number of bytes
397  */
398 static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)
399 {
400         return tfm->reqsize;
401 }
402 
403 /**
404  * aead_request_set_tfm() - update cipher handle reference in request
405  * @req: request handle to be modified
406  * @tfm: cipher handle that shall be added to the request handle
407  *
408  * Allow the caller to replace the existing aead handle in the request
409  * data structure with a different one.
410  */
411 static inline void aead_request_set_tfm(struct aead_request *req,
412                                         struct crypto_aead *tfm)
413 {
414         req->base.tfm = crypto_aead_tfm(tfm);
415 }
416 
417 /**
418  * aead_request_alloc() - allocate request data structure
419  * @tfm: cipher handle to be registered with the request
420  * @gfp: memory allocation flag that is handed to kmalloc by the API call.
421  *
422  * Allocate the request data structure that must be used with the AEAD
423  * encrypt and decrypt API calls. During the allocation, the provided aead
424  * handle is registered in the request data structure.
425  *
426  * Return: allocated request handle in case of success, or NULL if out of memory
427  */
428 static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
429                                                       gfp_t gfp)
430 {
431         struct aead_request *req;
432 
433         req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);
434 
435         if (likely(req))
436                 aead_request_set_tfm(req, tfm);
437 
438         return req;
439 }
440 
441 /**
442  * aead_request_free() - zeroize and free request data structure
443  * @req: request data structure cipher handle to be freed
444  */
445 static inline void aead_request_free(struct aead_request *req)
446 {
447         kzfree(req);
448 }
449 
450 /**
451  * aead_request_set_callback() - set asynchronous callback function
452  * @req: request handle
453  * @flags: specify zero or an ORing of the flags
454  *         CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
455  *         increase the wait queue beyond the initial maximum size;
456  *         CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
457  * @compl: callback function pointer to be registered with the request handle
458  * @data: The data pointer refers to memory that is not used by the kernel
459  *        crypto API, but provided to the callback function for it to use. Here,
460  *        the caller can provide a reference to memory the callback function can
461  *        operate on. As the callback function is invoked asynchronously to the
462  *        related functionality, it may need to access data structures of the
463  *        related functionality which can be referenced using this pointer. The
464  *        callback function can access the memory via the "data" field in the
465  *        crypto_async_request data structure provided to the callback function.
466  *
467  * Setting the callback function that is triggered once the cipher operation
468  * completes
469  *
470  * The callback function is registered with the aead_request handle and
471  * must comply with the following template::
472  *
473  *      void callback_function(struct crypto_async_request *req, int error)
474  */
475 static inline void aead_request_set_callback(struct aead_request *req,
476                                              u32 flags,
477                                              crypto_completion_t compl,
478                                              void *data)
479 {
480         req->base.complete = compl;
481         req->base.data = data;
482         req->base.flags = flags;
483 }
484 
485 /**
486  * aead_request_set_crypt - set data buffers
487  * @req: request handle
488  * @src: source scatter / gather list
489  * @dst: destination scatter / gather list
490  * @cryptlen: number of bytes to process from @src
491  * @iv: IV for the cipher operation which must comply with the IV size defined
492  *      by crypto_aead_ivsize()
493  *
494  * Setting the source data and destination data scatter / gather lists which
495  * hold the associated data concatenated with the plaintext or ciphertext. See
496  * below for the authentication tag.
497  *
498  * For encryption, the source is treated as the plaintext and the
499  * destination is the ciphertext. For a decryption operation, the use is
500  * reversed - the source is the ciphertext and the destination is the plaintext.
501  *
502  * The memory structure for cipher operation has the following structure:
503  *
504  * - AEAD encryption input:  assoc data || plaintext
505  * - AEAD encryption output: assoc data || cipherntext || auth tag
506  * - AEAD decryption input:  assoc data || ciphertext || auth tag
507  * - AEAD decryption output: assoc data || plaintext
508  *
509  * Albeit the kernel requires the presence of the AAD buffer, however,
510  * the kernel does not fill the AAD buffer in the output case. If the
511  * caller wants to have that data buffer filled, the caller must either
512  * use an in-place cipher operation (i.e. same memory location for
513  * input/output memory location).
514  */
515 static inline void aead_request_set_crypt(struct aead_request *req,
516                                           struct scatterlist *src,
517                                           struct scatterlist *dst,
518                                           unsigned int cryptlen, u8 *iv)
519 {
520         req->src = src;
521         req->dst = dst;
522         req->cryptlen = cryptlen;
523         req->iv = iv;
524 }
525 
526 /**
527  * aead_request_set_ad - set associated data information
528  * @req: request handle
529  * @assoclen: number of bytes in associated data
530  *
531  * Setting the AD information.  This function sets the length of
532  * the associated data.
533  */
534 static inline void aead_request_set_ad(struct aead_request *req,
535                                        unsigned int assoclen)
536 {
537         req->assoclen = assoclen;
538 }
539 
540 #endif  /* _CRYPTO_AEAD_H */
541 

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