1 /* 2 * AEAD: Authenticated Encryption with Associated Data 3 * 4 * Copyright (c) 2007 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 asynchronous block cipher operation 35 * applies here as well. Naturally all *ablkcipher* symbols must be exchanged 36 * the *aead* pendants discussed in the following. In addition, for the AEAD 37 * operation, the aead_request_set_assoc 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 50 /** 51 * struct aead_request - AEAD request 52 * @base: Common attributes for async crypto requests 53 * @old: Boolean whether the old or new AEAD API is used 54 * @assoclen: Length in bytes of associated data for authentication 55 * @cryptlen: Length of data to be encrypted or decrypted 56 * @iv: Initialisation vector 57 * @assoc: Associated data 58 * @src: Source data 59 * @dst: Destination data 60 * @__ctx: Start of private context data 61 */ 62 struct aead_request { 63 struct crypto_async_request base; 64 65 bool old; 66 67 unsigned int assoclen; 68 unsigned int cryptlen; 69 70 u8 *iv; 71 72 struct scatterlist *assoc; 73 struct scatterlist *src; 74 struct scatterlist *dst; 75 76 void *__ctx[] CRYPTO_MINALIGN_ATTR; 77 }; 78 79 /** 80 * struct aead_givcrypt_request - AEAD request with IV generation 81 * @seq: Sequence number for IV generation 82 * @giv: Space for generated IV 83 * @areq: The AEAD request itself 84 */ 85 struct aead_givcrypt_request { 86 u64 seq; 87 u8 *giv; 88 89 struct aead_request areq; 90 }; 91 92 /** 93 * struct aead_alg - AEAD cipher definition 94 * @maxauthsize: Set the maximum authentication tag size supported by the 95 * transformation. A transformation may support smaller tag sizes. 96 * As the authentication tag is a message digest to ensure the 97 * integrity of the encrypted data, a consumer typically wants the 98 * largest authentication tag possible as defined by this 99 * variable. 100 * @setauthsize: Set authentication size for the AEAD transformation. This 101 * function is used to specify the consumer requested size of the 102 * authentication tag to be either generated by the transformation 103 * during encryption or the size of the authentication tag to be 104 * supplied during the decryption operation. This function is also 105 * responsible for checking the authentication tag size for 106 * validity. 107 * @setkey: see struct ablkcipher_alg 108 * @encrypt: see struct ablkcipher_alg 109 * @decrypt: see struct ablkcipher_alg 110 * @geniv: see struct ablkcipher_alg 111 * @ivsize: see struct ablkcipher_alg 112 * @init: Initialize the cryptographic transformation object. This function 113 * is used to initialize the cryptographic transformation object. 114 * This function is called only once at the instantiation time, right 115 * after the transformation context was allocated. In case the 116 * cryptographic hardware has some special requirements which need to 117 * be handled by software, this function shall check for the precise 118 * requirement of the transformation and put any software fallbacks 119 * in place. 120 * @exit: Deinitialize the cryptographic transformation object. This is a 121 * counterpart to @init, used to remove various changes set in 122 * @init. 123 * 124 * All fields except @ivsize is mandatory and must be filled. 125 */ 126 struct aead_alg { 127 int (*setkey)(struct crypto_aead *tfm, const u8 *key, 128 unsigned int keylen); 129 int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize); 130 int (*encrypt)(struct aead_request *req); 131 int (*decrypt)(struct aead_request *req); 132 int (*init)(struct crypto_aead *tfm); 133 void (*exit)(struct crypto_aead *tfm); 134 135 const char *geniv; 136 137 unsigned int ivsize; 138 unsigned int maxauthsize; 139 140 struct crypto_alg base; 141 }; 142 143 struct crypto_aead { 144 int (*setkey)(struct crypto_aead *tfm, const u8 *key, 145 unsigned int keylen); 146 int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize); 147 int (*encrypt)(struct aead_request *req); 148 int (*decrypt)(struct aead_request *req); 149 int (*givencrypt)(struct aead_givcrypt_request *req); 150 int (*givdecrypt)(struct aead_givcrypt_request *req); 151 152 struct crypto_aead *child; 153 154 unsigned int authsize; 155 unsigned int reqsize; 156 157 struct crypto_tfm base; 158 }; 159 160 static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm) 161 { 162 return container_of(tfm, struct crypto_aead, base); 163 } 164 165 /** 166 * crypto_alloc_aead() - allocate AEAD cipher handle 167 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the 168 * AEAD cipher 169 * @type: specifies the type of the cipher 170 * @mask: specifies the mask for the cipher 171 * 172 * Allocate a cipher handle for an AEAD. The returned struct 173 * crypto_aead is the cipher handle that is required for any subsequent 174 * API invocation for that AEAD. 175 * 176 * Return: allocated cipher handle in case of success; IS_ERR() is true in case 177 * of an error, PTR_ERR() returns the error code. 178 */ 179 struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask); 180 181 static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm) 182 { 183 return &tfm->base; 184 } 185 186 /** 187 * crypto_free_aead() - zeroize and free aead handle 188 * @tfm: cipher handle to be freed 189 */ 190 static inline void crypto_free_aead(struct crypto_aead *tfm) 191 { 192 crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm)); 193 } 194 195 static inline struct crypto_aead *crypto_aead_crt(struct crypto_aead *tfm) 196 { 197 return tfm; 198 } 199 200 static inline struct old_aead_alg *crypto_old_aead_alg(struct crypto_aead *tfm) 201 { 202 return &crypto_aead_tfm(tfm)->__crt_alg->cra_aead; 203 } 204 205 static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm) 206 { 207 return container_of(crypto_aead_tfm(tfm)->__crt_alg, 208 struct aead_alg, base); 209 } 210 211 static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg) 212 { 213 return alg->base.cra_aead.encrypt ? alg->base.cra_aead.ivsize : 214 alg->ivsize; 215 } 216 217 /** 218 * crypto_aead_ivsize() - obtain IV size 219 * @tfm: cipher handle 220 * 221 * The size of the IV for the aead referenced by the cipher handle is 222 * returned. This IV size may be zero if the cipher does not need an IV. 223 * 224 * Return: IV size in bytes 225 */ 226 static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm) 227 { 228 return crypto_aead_alg_ivsize(crypto_aead_alg(tfm)); 229 } 230 231 /** 232 * crypto_aead_authsize() - obtain maximum authentication data size 233 * @tfm: cipher handle 234 * 235 * The maximum size of the authentication data for the AEAD cipher referenced 236 * by the AEAD cipher handle is returned. The authentication data size may be 237 * zero if the cipher implements a hard-coded maximum. 238 * 239 * The authentication data may also be known as "tag value". 240 * 241 * Return: authentication data size / tag size in bytes 242 */ 243 static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm) 244 { 245 return tfm->authsize; 246 } 247 248 /** 249 * crypto_aead_blocksize() - obtain block size of cipher 250 * @tfm: cipher handle 251 * 252 * The block size for the AEAD referenced with the cipher handle is returned. 253 * The caller may use that information to allocate appropriate memory for the 254 * data returned by the encryption or decryption operation 255 * 256 * Return: block size of cipher 257 */ 258 static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm) 259 { 260 return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm)); 261 } 262 263 static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm) 264 { 265 return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm)); 266 } 267 268 static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm) 269 { 270 return crypto_tfm_get_flags(crypto_aead_tfm(tfm)); 271 } 272 273 static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags) 274 { 275 crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags); 276 } 277 278 static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags) 279 { 280 crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags); 281 } 282 283 /** 284 * crypto_aead_setkey() - set key for cipher 285 * @tfm: cipher handle 286 * @key: buffer holding the key 287 * @keylen: length of the key in bytes 288 * 289 * The caller provided key is set for the AEAD referenced by the cipher 290 * handle. 291 * 292 * Note, the key length determines the cipher type. Many block ciphers implement 293 * different cipher modes depending on the key size, such as AES-128 vs AES-192 294 * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128 295 * is performed. 296 * 297 * Return: 0 if the setting of the key was successful; < 0 if an error occurred 298 */ 299 int crypto_aead_setkey(struct crypto_aead *tfm, 300 const u8 *key, unsigned int keylen); 301 302 /** 303 * crypto_aead_setauthsize() - set authentication data size 304 * @tfm: cipher handle 305 * @authsize: size of the authentication data / tag in bytes 306 * 307 * Set the authentication data size / tag size. AEAD requires an authentication 308 * tag (or MAC) in addition to the associated data. 309 * 310 * Return: 0 if the setting of the key was successful; < 0 if an error occurred 311 */ 312 int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize); 313 314 static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req) 315 { 316 return __crypto_aead_cast(req->base.tfm); 317 } 318 319 /** 320 * crypto_aead_encrypt() - encrypt plaintext 321 * @req: reference to the aead_request handle that holds all information 322 * needed to perform the cipher operation 323 * 324 * Encrypt plaintext data using the aead_request handle. That data structure 325 * and how it is filled with data is discussed with the aead_request_* 326 * functions. 327 * 328 * IMPORTANT NOTE The encryption operation creates the authentication data / 329 * tag. That data is concatenated with the created ciphertext. 330 * The ciphertext memory size is therefore the given number of 331 * block cipher blocks + the size defined by the 332 * crypto_aead_setauthsize invocation. The caller must ensure 333 * that sufficient memory is available for the ciphertext and 334 * the authentication tag. 335 * 336 * Return: 0 if the cipher operation was successful; < 0 if an error occurred 337 */ 338 static inline int crypto_aead_encrypt(struct aead_request *req) 339 { 340 return crypto_aead_reqtfm(req)->encrypt(req); 341 } 342 343 /** 344 * crypto_aead_decrypt() - decrypt ciphertext 345 * @req: reference to the ablkcipher_request handle that holds all information 346 * needed to perform the cipher operation 347 * 348 * Decrypt ciphertext data using the aead_request handle. That data structure 349 * and how it is filled with data is discussed with the aead_request_* 350 * functions. 351 * 352 * IMPORTANT NOTE The caller must concatenate the ciphertext followed by the 353 * authentication data / tag. That authentication data / tag 354 * must have the size defined by the crypto_aead_setauthsize 355 * invocation. 356 * 357 * 358 * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD 359 * cipher operation performs the authentication of the data during the 360 * decryption operation. Therefore, the function returns this error if 361 * the authentication of the ciphertext was unsuccessful (i.e. the 362 * integrity of the ciphertext or the associated data was violated); 363 * < 0 if an error occurred. 364 */ 365 static inline int crypto_aead_decrypt(struct aead_request *req) 366 { 367 if (req->cryptlen < crypto_aead_authsize(crypto_aead_reqtfm(req))) 368 return -EINVAL; 369 370 return crypto_aead_reqtfm(req)->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 unsigned int crypto_aead_reqsize(struct crypto_aead *tfm); 391 392 /** 393 * aead_request_set_tfm() - update cipher handle reference in request 394 * @req: request handle to be modified 395 * @tfm: cipher handle that shall be added to the request handle 396 * 397 * Allow the caller to replace the existing aead handle in the request 398 * data structure with a different one. 399 */ 400 static inline void aead_request_set_tfm(struct aead_request *req, 401 struct crypto_aead *tfm) 402 { 403 req->base.tfm = crypto_aead_tfm(tfm->child); 404 } 405 406 /** 407 * aead_request_alloc() - allocate request data structure 408 * @tfm: cipher handle to be registered with the request 409 * @gfp: memory allocation flag that is handed to kmalloc by the API call. 410 * 411 * Allocate the request data structure that must be used with the AEAD 412 * encrypt and decrypt API calls. During the allocation, the provided aead 413 * handle is registered in the request data structure. 414 * 415 * Return: allocated request handle in case of success; IS_ERR() is true in case 416 * of an error, PTR_ERR() returns the error code. 417 */ 418 static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm, 419 gfp_t gfp) 420 { 421 struct aead_request *req; 422 423 req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp); 424 425 if (likely(req)) 426 aead_request_set_tfm(req, tfm); 427 428 return req; 429 } 430 431 /** 432 * aead_request_free() - zeroize and free request data structure 433 * @req: request data structure cipher handle to be freed 434 */ 435 static inline void aead_request_free(struct aead_request *req) 436 { 437 kzfree(req); 438 } 439 440 /** 441 * aead_request_set_callback() - set asynchronous callback function 442 * @req: request handle 443 * @flags: specify zero or an ORing of the flags 444 * CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and 445 * increase the wait queue beyond the initial maximum size; 446 * CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep 447 * @compl: callback function pointer to be registered with the request handle 448 * @data: The data pointer refers to memory that is not used by the kernel 449 * crypto API, but provided to the callback function for it to use. Here, 450 * the caller can provide a reference to memory the callback function can 451 * operate on. As the callback function is invoked asynchronously to the 452 * related functionality, it may need to access data structures of the 453 * related functionality which can be referenced using this pointer. The 454 * callback function can access the memory via the "data" field in the 455 * crypto_async_request data structure provided to the callback function. 456 * 457 * Setting the callback function that is triggered once the cipher operation 458 * completes 459 * 460 * The callback function is registered with the aead_request handle and 461 * must comply with the following template 462 * 463 * void callback_function(struct crypto_async_request *req, int error) 464 */ 465 static inline void aead_request_set_callback(struct aead_request *req, 466 u32 flags, 467 crypto_completion_t compl, 468 void *data) 469 { 470 req->base.complete = compl; 471 req->base.data = data; 472 req->base.flags = flags; 473 } 474 475 /** 476 * aead_request_set_crypt - set data buffers 477 * @req: request handle 478 * @src: source scatter / gather list 479 * @dst: destination scatter / gather list 480 * @cryptlen: number of bytes to process from @src 481 * @iv: IV for the cipher operation which must comply with the IV size defined 482 * by crypto_aead_ivsize() 483 * 484 * Setting the source data and destination data scatter / gather lists which 485 * hold the associated data concatenated with the plaintext or ciphertext. See 486 * below for the authentication tag. 487 * 488 * For encryption, the source is treated as the plaintext and the 489 * destination is the ciphertext. For a decryption operation, the use is 490 * reversed - the source is the ciphertext and the destination is the plaintext. 491 * 492 * For both src/dst the layout is associated data, plain/cipher text, 493 * authentication tag. 494 * 495 * The content of the AD in the destination buffer after processing 496 * will either be untouched, or it will contain a copy of the AD 497 * from the source buffer. In order to ensure that it always has 498 * a copy of the AD, the user must copy the AD over either before 499 * or after processing. Of course this is not relevant if the user 500 * is doing in-place processing where src == dst. 501 * 502 * IMPORTANT NOTE AEAD requires an authentication tag (MAC). For decryption, 503 * the caller must concatenate the ciphertext followed by the 504 * authentication tag and provide the entire data stream to the 505 * decryption operation (i.e. the data length used for the 506 * initialization of the scatterlist and the data length for the 507 * decryption operation is identical). For encryption, however, 508 * the authentication tag is created while encrypting the data. 509 * The destination buffer must hold sufficient space for the 510 * ciphertext and the authentication tag while the encryption 511 * invocation must only point to the plaintext data size. The 512 * following code snippet illustrates the memory usage 513 * buffer = kmalloc(ptbuflen + (enc ? authsize : 0)); 514 * sg_init_one(&sg, buffer, ptbuflen + (enc ? authsize : 0)); 515 * aead_request_set_crypt(req, &sg, &sg, ptbuflen, iv); 516 */ 517 static inline void aead_request_set_crypt(struct aead_request *req, 518 struct scatterlist *src, 519 struct scatterlist *dst, 520 unsigned int cryptlen, u8 *iv) 521 { 522 req->src = src; 523 req->dst = dst; 524 req->cryptlen = cryptlen; 525 req->iv = iv; 526 } 527 528 /** 529 * aead_request_set_assoc() - set the associated data scatter / gather list 530 * @req: request handle 531 * @assoc: associated data scatter / gather list 532 * @assoclen: number of bytes to process from @assoc 533 * 534 * Obsolete, do not use. 535 */ 536 static inline void aead_request_set_assoc(struct aead_request *req, 537 struct scatterlist *assoc, 538 unsigned int assoclen) 539 { 540 req->assoc = assoc; 541 req->assoclen = assoclen; 542 req->old = true; 543 } 544 545 /** 546 * aead_request_set_ad - set associated data information 547 * @req: request handle 548 * @assoclen: number of bytes in associated data 549 * 550 * Setting the AD information. This function sets the length of 551 * the associated data. 552 */ 553 static inline void aead_request_set_ad(struct aead_request *req, 554 unsigned int assoclen) 555 { 556 req->assoclen = assoclen; 557 req->old = false; 558 } 559 560 static inline struct crypto_aead *aead_givcrypt_reqtfm( 561 struct aead_givcrypt_request *req) 562 { 563 return crypto_aead_reqtfm(&req->areq); 564 } 565 566 static inline int crypto_aead_givencrypt(struct aead_givcrypt_request *req) 567 { 568 return aead_givcrypt_reqtfm(req)->givencrypt(req); 569 }; 570 571 static inline int crypto_aead_givdecrypt(struct aead_givcrypt_request *req) 572 { 573 return aead_givcrypt_reqtfm(req)->givdecrypt(req); 574 }; 575 576 static inline void aead_givcrypt_set_tfm(struct aead_givcrypt_request *req, 577 struct crypto_aead *tfm) 578 { 579 req->areq.base.tfm = crypto_aead_tfm(tfm); 580 } 581 582 static inline struct aead_givcrypt_request *aead_givcrypt_alloc( 583 struct crypto_aead *tfm, gfp_t gfp) 584 { 585 struct aead_givcrypt_request *req; 586 587 req = kmalloc(sizeof(struct aead_givcrypt_request) + 588 crypto_aead_reqsize(tfm), gfp); 589 590 if (likely(req)) 591 aead_givcrypt_set_tfm(req, tfm); 592 593 return req; 594 } 595 596 static inline void aead_givcrypt_free(struct aead_givcrypt_request *req) 597 { 598 kfree(req); 599 } 600 601 static inline void aead_givcrypt_set_callback( 602 struct aead_givcrypt_request *req, u32 flags, 603 crypto_completion_t compl, void *data) 604 { 605 aead_request_set_callback(&req->areq, flags, compl, data); 606 } 607 608 static inline void aead_givcrypt_set_crypt(struct aead_givcrypt_request *req, 609 struct scatterlist *src, 610 struct scatterlist *dst, 611 unsigned int nbytes, void *iv) 612 { 613 aead_request_set_crypt(&req->areq, src, dst, nbytes, iv); 614 } 615 616 static inline void aead_givcrypt_set_assoc(struct aead_givcrypt_request *req, 617 struct scatterlist *assoc, 618 unsigned int assoclen) 619 { 620 aead_request_set_assoc(&req->areq, assoc, assoclen); 621 } 622 623 static inline void aead_givcrypt_set_giv(struct aead_givcrypt_request *req, 624 u8 *giv, u64 seq) 625 { 626 req->giv = giv; 627 req->seq = seq; 628 } 629 630 #endif /* _CRYPTO_AEAD_H */ 631