1 /* SPDX-License-Identifier: GPL-2.0-or-later */
3 * AEAD: Authenticated Encryption with Associated Data
5 * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
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>
18 * DOC: Authenticated Encryption With Associated Data (AEAD) Cipher API
20 * The AEAD cipher API is used with the ciphers of type CRYPTO_ALG_TYPE_AEAD
21 * (listed as type "aead" in /proc/crypto)
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:
27 * authenc(keyed message digest, block cipher)
29 * For example: authenc(hmac(sha256), cbc(aes))
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
45 * The source scatterlist must contain the concatenation of
46 * associated data || plaintext or ciphertext.
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.
55 * In-place encryption/decryption is enabled by using the same scatterlist
56 * pointer for both the source and destination.
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.
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.
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.
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
87 * @dst: Destination data
88 * @__ctx: Start of private context data
91 struct crypto_async_request base;
93 unsigned int assoclen;
94 unsigned int cryptlen;
98 struct scatterlist *src;
99 struct scatterlist *dst;
101 void *__ctx[] CRYPTO_MINALIGN_ATTR;
105 * struct crypto_istat_aead - statistics for AEAD algorithm
106 * @encrypt_cnt: number of encrypt requests
107 * @encrypt_tlen: total data size handled by encrypt requests
108 * @decrypt_cnt: number of decrypt requests
109 * @decrypt_tlen: total data size handled by decrypt requests
110 * @err_cnt: number of error for AEAD requests
112 struct crypto_istat_aead {
113 atomic64_t encrypt_cnt;
114 atomic64_t encrypt_tlen;
115 atomic64_t decrypt_cnt;
116 atomic64_t decrypt_tlen;
121 * struct aead_alg - AEAD cipher definition
122 * @maxauthsize: Set the maximum authentication tag size supported by the
123 * transformation. A transformation may support smaller tag sizes.
124 * As the authentication tag is a message digest to ensure the
125 * integrity of the encrypted data, a consumer typically wants the
126 * largest authentication tag possible as defined by this
128 * @setauthsize: Set authentication size for the AEAD transformation. This
129 * function is used to specify the consumer requested size of the
130 * authentication tag to be either generated by the transformation
131 * during encryption or the size of the authentication tag to be
132 * supplied during the decryption operation. This function is also
133 * responsible for checking the authentication tag size for
135 * @setkey: see struct skcipher_alg
136 * @encrypt: see struct skcipher_alg
137 * @decrypt: see struct skcipher_alg
138 * @stat: statistics for AEAD algorithm
139 * @ivsize: see struct skcipher_alg
140 * @chunksize: see struct skcipher_alg
141 * @init: Initialize the cryptographic transformation object. This function
142 * is used to initialize the cryptographic transformation object.
143 * This function is called only once at the instantiation time, right
144 * after the transformation context was allocated. In case the
145 * cryptographic hardware has some special requirements which need to
146 * be handled by software, this function shall check for the precise
147 * requirement of the transformation and put any software fallbacks
149 * @exit: Deinitialize the cryptographic transformation object. This is a
150 * counterpart to @init, used to remove various changes set in
152 * @base: Definition of a generic crypto cipher algorithm.
154 * All fields except @ivsize is mandatory and must be filled.
157 int (*setkey)(struct crypto_aead *tfm, const u8 *key,
158 unsigned int keylen);
159 int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize);
160 int (*encrypt)(struct aead_request *req);
161 int (*decrypt)(struct aead_request *req);
162 int (*init)(struct crypto_aead *tfm);
163 void (*exit)(struct crypto_aead *tfm);
165 #ifdef CONFIG_CRYPTO_STATS
166 struct crypto_istat_aead stat;
170 unsigned int maxauthsize;
171 unsigned int chunksize;
173 struct crypto_alg base;
177 unsigned int authsize;
178 unsigned int reqsize;
180 struct crypto_tfm base;
183 static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
185 return container_of(tfm, struct crypto_aead, base);
189 * crypto_alloc_aead() - allocate AEAD cipher handle
190 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
192 * @type: specifies the type of the cipher
193 * @mask: specifies the mask for the cipher
195 * Allocate a cipher handle for an AEAD. The returned struct
196 * crypto_aead is the cipher handle that is required for any subsequent
197 * API invocation for that AEAD.
199 * Return: allocated cipher handle in case of success; IS_ERR() is true in case
200 * of an error, PTR_ERR() returns the error code.
202 struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);
204 static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
210 * crypto_free_aead() - zeroize and free aead handle
211 * @tfm: cipher handle to be freed
213 * If @tfm is a NULL or error pointer, this function does nothing.
215 static inline void crypto_free_aead(struct crypto_aead *tfm)
217 crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
221 * crypto_has_aead() - Search for the availability of an aead.
222 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
224 * @type: specifies the type of the aead
225 * @mask: specifies the mask for the aead
227 * Return: true when the aead is known to the kernel crypto API; false
230 int crypto_has_aead(const char *alg_name, u32 type, u32 mask);
232 static inline const char *crypto_aead_driver_name(struct crypto_aead *tfm)
234 return crypto_tfm_alg_driver_name(crypto_aead_tfm(tfm));
237 static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
239 return container_of(crypto_aead_tfm(tfm)->__crt_alg,
240 struct aead_alg, base);
243 static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
249 * crypto_aead_ivsize() - obtain IV size
250 * @tfm: cipher handle
252 * The size of the IV for the aead referenced by the cipher handle is
253 * returned. This IV size may be zero if the cipher does not need an IV.
255 * Return: IV size in bytes
257 static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)
259 return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
263 * crypto_aead_authsize() - obtain maximum authentication data size
264 * @tfm: cipher handle
266 * The maximum size of the authentication data for the AEAD cipher referenced
267 * by the AEAD cipher handle is returned. The authentication data size may be
268 * zero if the cipher implements a hard-coded maximum.
270 * The authentication data may also be known as "tag value".
272 * Return: authentication data size / tag size in bytes
274 static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)
276 return tfm->authsize;
279 static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg)
281 return alg->maxauthsize;
284 static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead)
286 return crypto_aead_alg_maxauthsize(crypto_aead_alg(aead));
290 * crypto_aead_blocksize() - obtain block size of cipher
291 * @tfm: cipher handle
293 * The block size for the AEAD referenced with the cipher handle is returned.
294 * The caller may use that information to allocate appropriate memory for the
295 * data returned by the encryption or decryption operation
297 * Return: block size of cipher
299 static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
301 return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
304 static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
306 return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));
309 static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)
311 return crypto_tfm_get_flags(crypto_aead_tfm(tfm));
314 static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)
316 crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);
319 static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)
321 crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
325 * crypto_aead_setkey() - set key for cipher
326 * @tfm: cipher handle
327 * @key: buffer holding the key
328 * @keylen: length of the key in bytes
330 * The caller provided key is set for the AEAD referenced by the cipher
333 * Note, the key length determines the cipher type. Many block ciphers implement
334 * different cipher modes depending on the key size, such as AES-128 vs AES-192
335 * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
338 * Return: 0 if the setting of the key was successful; < 0 if an error occurred
340 int crypto_aead_setkey(struct crypto_aead *tfm,
341 const u8 *key, unsigned int keylen);
344 * crypto_aead_setauthsize() - set authentication data size
345 * @tfm: cipher handle
346 * @authsize: size of the authentication data / tag in bytes
348 * Set the authentication data size / tag size. AEAD requires an authentication
349 * tag (or MAC) in addition to the associated data.
351 * Return: 0 if the setting of the key was successful; < 0 if an error occurred
353 int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);
355 static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
357 return __crypto_aead_cast(req->base.tfm);
361 * crypto_aead_encrypt() - encrypt plaintext
362 * @req: reference to the aead_request handle that holds all information
363 * needed to perform the cipher operation
365 * Encrypt plaintext data using the aead_request handle. That data structure
366 * and how it is filled with data is discussed with the aead_request_*
369 * IMPORTANT NOTE The encryption operation creates the authentication data /
370 * tag. That data is concatenated with the created ciphertext.
371 * The ciphertext memory size is therefore the given number of
372 * block cipher blocks + the size defined by the
373 * crypto_aead_setauthsize invocation. The caller must ensure
374 * that sufficient memory is available for the ciphertext and
375 * the authentication tag.
377 * Return: 0 if the cipher operation was successful; < 0 if an error occurred
379 int crypto_aead_encrypt(struct aead_request *req);
382 * crypto_aead_decrypt() - decrypt ciphertext
383 * @req: reference to the aead_request handle that holds all information
384 * needed to perform the cipher operation
386 * Decrypt ciphertext data using the aead_request handle. That data structure
387 * and how it is filled with data is discussed with the aead_request_*
390 * IMPORTANT NOTE The caller must concatenate the ciphertext followed by the
391 * authentication data / tag. That authentication data / tag
392 * must have the size defined by the crypto_aead_setauthsize
396 * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
397 * cipher operation performs the authentication of the data during the
398 * decryption operation. Therefore, the function returns this error if
399 * the authentication of the ciphertext was unsuccessful (i.e. the
400 * integrity of the ciphertext or the associated data was violated);
401 * < 0 if an error occurred.
403 int crypto_aead_decrypt(struct aead_request *req);
406 * DOC: Asynchronous AEAD Request Handle
408 * The aead_request data structure contains all pointers to data required for
409 * the AEAD cipher operation. This includes the cipher handle (which can be
410 * used by multiple aead_request instances), pointer to plaintext and
411 * ciphertext, asynchronous callback function, etc. It acts as a handle to the
412 * aead_request_* API calls in a similar way as AEAD handle to the
413 * crypto_aead_* API calls.
417 * crypto_aead_reqsize() - obtain size of the request data structure
418 * @tfm: cipher handle
420 * Return: number of bytes
422 static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)
428 * aead_request_set_tfm() - update cipher handle reference in request
429 * @req: request handle to be modified
430 * @tfm: cipher handle that shall be added to the request handle
432 * Allow the caller to replace the existing aead handle in the request
433 * data structure with a different one.
435 static inline void aead_request_set_tfm(struct aead_request *req,
436 struct crypto_aead *tfm)
438 req->base.tfm = crypto_aead_tfm(tfm);
442 * aead_request_alloc() - allocate request data structure
443 * @tfm: cipher handle to be registered with the request
444 * @gfp: memory allocation flag that is handed to kmalloc by the API call.
446 * Allocate the request data structure that must be used with the AEAD
447 * encrypt and decrypt API calls. During the allocation, the provided aead
448 * handle is registered in the request data structure.
450 * Return: allocated request handle in case of success, or NULL if out of memory
452 static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
455 struct aead_request *req;
457 req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);
460 aead_request_set_tfm(req, tfm);
466 * aead_request_free() - zeroize and free request data structure
467 * @req: request data structure cipher handle to be freed
469 static inline void aead_request_free(struct aead_request *req)
471 kfree_sensitive(req);
475 * aead_request_set_callback() - set asynchronous callback function
476 * @req: request handle
477 * @flags: specify zero or an ORing of the flags
478 * CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
479 * increase the wait queue beyond the initial maximum size;
480 * CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
481 * @compl: callback function pointer to be registered with the request handle
482 * @data: The data pointer refers to memory that is not used by the kernel
483 * crypto API, but provided to the callback function for it to use. Here,
484 * the caller can provide a reference to memory the callback function can
485 * operate on. As the callback function is invoked asynchronously to the
486 * related functionality, it may need to access data structures of the
487 * related functionality which can be referenced using this pointer. The
488 * callback function can access the memory via the "data" field in the
489 * crypto_async_request data structure provided to the callback function.
491 * Setting the callback function that is triggered once the cipher operation
494 * The callback function is registered with the aead_request handle and
495 * must comply with the following template::
497 * void callback_function(struct crypto_async_request *req, int error)
499 static inline void aead_request_set_callback(struct aead_request *req,
501 crypto_completion_t compl,
504 req->base.complete = compl;
505 req->base.data = data;
506 req->base.flags = flags;
510 * aead_request_set_crypt - set data buffers
511 * @req: request handle
512 * @src: source scatter / gather list
513 * @dst: destination scatter / gather list
514 * @cryptlen: number of bytes to process from @src
515 * @iv: IV for the cipher operation which must comply with the IV size defined
516 * by crypto_aead_ivsize()
518 * Setting the source data and destination data scatter / gather lists which
519 * hold the associated data concatenated with the plaintext or ciphertext. See
520 * below for the authentication tag.
522 * For encryption, the source is treated as the plaintext and the
523 * destination is the ciphertext. For a decryption operation, the use is
524 * reversed - the source is the ciphertext and the destination is the plaintext.
526 * The memory structure for cipher operation has the following structure:
528 * - AEAD encryption input: assoc data || plaintext
529 * - AEAD encryption output: assoc data || ciphertext || auth tag
530 * - AEAD decryption input: assoc data || ciphertext || auth tag
531 * - AEAD decryption output: assoc data || plaintext
533 * Albeit the kernel requires the presence of the AAD buffer, however,
534 * the kernel does not fill the AAD buffer in the output case. If the
535 * caller wants to have that data buffer filled, the caller must either
536 * use an in-place cipher operation (i.e. same memory location for
537 * input/output memory location).
539 static inline void aead_request_set_crypt(struct aead_request *req,
540 struct scatterlist *src,
541 struct scatterlist *dst,
542 unsigned int cryptlen, u8 *iv)
546 req->cryptlen = cryptlen;
551 * aead_request_set_ad - set associated data information
552 * @req: request handle
553 * @assoclen: number of bytes in associated data
555 * Setting the AD information. This function sets the length of
556 * the associated data.
558 static inline void aead_request_set_ad(struct aead_request *req,
559 unsigned int assoclen)
561 req->assoclen = assoclen;
564 #endif /* _CRYPTO_AEAD_H */