linux/include/crypto/skcipher.h
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   1/* SPDX-License-Identifier: GPL-2.0-or-later */
   2/*
   3 * Symmetric key ciphers.
   4 * 
   5 * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
   6 */
   7
   8#ifndef _CRYPTO_SKCIPHER_H
   9#define _CRYPTO_SKCIPHER_H
  10
  11#include <linux/crypto.h>
  12#include <linux/kernel.h>
  13#include <linux/slab.h>
  14
  15/**
  16 *      struct skcipher_request - Symmetric key cipher request
  17 *      @cryptlen: Number of bytes to encrypt or decrypt
  18 *      @iv: Initialisation Vector
  19 *      @src: Source SG list
  20 *      @dst: Destination SG list
  21 *      @base: Underlying async request
  22 *      @__ctx: Start of private context data
  23 */
  24struct skcipher_request {
  25        unsigned int cryptlen;
  26
  27        u8 *iv;
  28
  29        struct scatterlist *src;
  30        struct scatterlist *dst;
  31
  32        struct crypto_async_request base;
  33
  34        void *__ctx[] CRYPTO_MINALIGN_ATTR;
  35};
  36
  37struct crypto_skcipher {
  38        unsigned int reqsize;
  39
  40        struct crypto_tfm base;
  41};
  42
  43struct crypto_sync_skcipher {
  44        struct crypto_skcipher base;
  45};
  46
  47/**
  48 * struct skcipher_alg - symmetric key cipher definition
  49 * @min_keysize: Minimum key size supported by the transformation. This is the
  50 *               smallest key length supported by this transformation algorithm.
  51 *               This must be set to one of the pre-defined values as this is
  52 *               not hardware specific. Possible values for this field can be
  53 *               found via git grep "_MIN_KEY_SIZE" include/crypto/
  54 * @max_keysize: Maximum key size supported by the transformation. This is the
  55 *               largest key length supported by this transformation algorithm.
  56 *               This must be set to one of the pre-defined values as this is
  57 *               not hardware specific. Possible values for this field can be
  58 *               found via git grep "_MAX_KEY_SIZE" include/crypto/
  59 * @setkey: Set key for the transformation. This function is used to either
  60 *          program a supplied key into the hardware or store the key in the
  61 *          transformation context for programming it later. Note that this
  62 *          function does modify the transformation context. This function can
  63 *          be called multiple times during the existence of the transformation
  64 *          object, so one must make sure the key is properly reprogrammed into
  65 *          the hardware. This function is also responsible for checking the key
  66 *          length for validity. In case a software fallback was put in place in
  67 *          the @cra_init call, this function might need to use the fallback if
  68 *          the algorithm doesn't support all of the key sizes.
  69 * @encrypt: Encrypt a scatterlist of blocks. This function is used to encrypt
  70 *           the supplied scatterlist containing the blocks of data. The crypto
  71 *           API consumer is responsible for aligning the entries of the
  72 *           scatterlist properly and making sure the chunks are correctly
  73 *           sized. In case a software fallback was put in place in the
  74 *           @cra_init call, this function might need to use the fallback if
  75 *           the algorithm doesn't support all of the key sizes. In case the
  76 *           key was stored in transformation context, the key might need to be
  77 *           re-programmed into the hardware in this function. This function
  78 *           shall not modify the transformation context, as this function may
  79 *           be called in parallel with the same transformation object.
  80 * @decrypt: Decrypt a single block. This is a reverse counterpart to @encrypt
  81 *           and the conditions are exactly the same.
  82 * @init: Initialize the cryptographic transformation object. This function
  83 *        is used to initialize the cryptographic transformation object.
  84 *        This function is called only once at the instantiation time, right
  85 *        after the transformation context was allocated. In case the
  86 *        cryptographic hardware has some special requirements which need to
  87 *        be handled by software, this function shall check for the precise
  88 *        requirement of the transformation and put any software fallbacks
  89 *        in place.
  90 * @exit: Deinitialize the cryptographic transformation object. This is a
  91 *        counterpart to @init, used to remove various changes set in
  92 *        @init.
  93 * @ivsize: IV size applicable for transformation. The consumer must provide an
  94 *          IV of exactly that size to perform the encrypt or decrypt operation.
  95 * @chunksize: Equal to the block size except for stream ciphers such as
  96 *             CTR where it is set to the underlying block size.
  97 * @walksize: Equal to the chunk size except in cases where the algorithm is
  98 *            considerably more efficient if it can operate on multiple chunks
  99 *            in parallel. Should be a multiple of chunksize.
 100 * @base: Definition of a generic crypto algorithm.
 101 *
 102 * All fields except @ivsize are mandatory and must be filled.
 103 */
 104struct skcipher_alg {
 105        int (*setkey)(struct crypto_skcipher *tfm, const u8 *key,
 106                      unsigned int keylen);
 107        int (*encrypt)(struct skcipher_request *req);
 108        int (*decrypt)(struct skcipher_request *req);
 109        int (*init)(struct crypto_skcipher *tfm);
 110        void (*exit)(struct crypto_skcipher *tfm);
 111
 112        unsigned int min_keysize;
 113        unsigned int max_keysize;
 114        unsigned int ivsize;
 115        unsigned int chunksize;
 116        unsigned int walksize;
 117
 118        struct crypto_alg base;
 119};
 120
 121#define MAX_SYNC_SKCIPHER_REQSIZE      384
 122/*
 123 * This performs a type-check against the "tfm" argument to make sure
 124 * all users have the correct skcipher tfm for doing on-stack requests.
 125 */
 126#define SYNC_SKCIPHER_REQUEST_ON_STACK(name, tfm) \
 127        char __##name##_desc[sizeof(struct skcipher_request) + \
 128                             MAX_SYNC_SKCIPHER_REQSIZE + \
 129                             (!(sizeof((struct crypto_sync_skcipher *)1 == \
 130                                       (typeof(tfm))1))) \
 131                            ] CRYPTO_MINALIGN_ATTR; \
 132        struct skcipher_request *name = (void *)__##name##_desc
 133
 134/**
 135 * DOC: Symmetric Key Cipher API
 136 *
 137 * Symmetric key cipher API is used with the ciphers of type
 138 * CRYPTO_ALG_TYPE_SKCIPHER (listed as type "skcipher" in /proc/crypto).
 139 *
 140 * Asynchronous cipher operations imply that the function invocation for a
 141 * cipher request returns immediately before the completion of the operation.
 142 * The cipher request is scheduled as a separate kernel thread and therefore
 143 * load-balanced on the different CPUs via the process scheduler. To allow
 144 * the kernel crypto API to inform the caller about the completion of a cipher
 145 * request, the caller must provide a callback function. That function is
 146 * invoked with the cipher handle when the request completes.
 147 *
 148 * To support the asynchronous operation, additional information than just the
 149 * cipher handle must be supplied to the kernel crypto API. That additional
 150 * information is given by filling in the skcipher_request data structure.
 151 *
 152 * For the symmetric key cipher API, the state is maintained with the tfm
 153 * cipher handle. A single tfm can be used across multiple calls and in
 154 * parallel. For asynchronous block cipher calls, context data supplied and
 155 * only used by the caller can be referenced the request data structure in
 156 * addition to the IV used for the cipher request. The maintenance of such
 157 * state information would be important for a crypto driver implementer to
 158 * have, because when calling the callback function upon completion of the
 159 * cipher operation, that callback function may need some information about
 160 * which operation just finished if it invoked multiple in parallel. This
 161 * state information is unused by the kernel crypto API.
 162 */
 163
 164static inline struct crypto_skcipher *__crypto_skcipher_cast(
 165        struct crypto_tfm *tfm)
 166{
 167        return container_of(tfm, struct crypto_skcipher, base);
 168}
 169
 170/**
 171 * crypto_alloc_skcipher() - allocate symmetric key cipher handle
 172 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
 173 *            skcipher cipher
 174 * @type: specifies the type of the cipher
 175 * @mask: specifies the mask for the cipher
 176 *
 177 * Allocate a cipher handle for an skcipher. The returned struct
 178 * crypto_skcipher is the cipher handle that is required for any subsequent
 179 * API invocation for that skcipher.
 180 *
 181 * Return: allocated cipher handle in case of success; IS_ERR() is true in case
 182 *         of an error, PTR_ERR() returns the error code.
 183 */
 184struct crypto_skcipher *crypto_alloc_skcipher(const char *alg_name,
 185                                              u32 type, u32 mask);
 186
 187struct crypto_sync_skcipher *crypto_alloc_sync_skcipher(const char *alg_name,
 188                                              u32 type, u32 mask);
 189
 190static inline struct crypto_tfm *crypto_skcipher_tfm(
 191        struct crypto_skcipher *tfm)
 192{
 193        return &tfm->base;
 194}
 195
 196/**
 197 * crypto_free_skcipher() - zeroize and free cipher handle
 198 * @tfm: cipher handle to be freed
 199 *
 200 * If @tfm is a NULL or error pointer, this function does nothing.
 201 */
 202static inline void crypto_free_skcipher(struct crypto_skcipher *tfm)
 203{
 204        crypto_destroy_tfm(tfm, crypto_skcipher_tfm(tfm));
 205}
 206
 207static inline void crypto_free_sync_skcipher(struct crypto_sync_skcipher *tfm)
 208{
 209        crypto_free_skcipher(&tfm->base);
 210}
 211
 212/**
 213 * crypto_has_skcipher() - Search for the availability of an skcipher.
 214 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
 215 *            skcipher
 216 * @type: specifies the type of the skcipher
 217 * @mask: specifies the mask for the skcipher
 218 *
 219 * Return: true when the skcipher is known to the kernel crypto API; false
 220 *         otherwise
 221 */
 222int crypto_has_skcipher(const char *alg_name, u32 type, u32 mask);
 223
 224static inline const char *crypto_skcipher_driver_name(
 225        struct crypto_skcipher *tfm)
 226{
 227        return crypto_tfm_alg_driver_name(crypto_skcipher_tfm(tfm));
 228}
 229
 230static inline struct skcipher_alg *crypto_skcipher_alg(
 231        struct crypto_skcipher *tfm)
 232{
 233        return container_of(crypto_skcipher_tfm(tfm)->__crt_alg,
 234                            struct skcipher_alg, base);
 235}
 236
 237static inline unsigned int crypto_skcipher_alg_ivsize(struct skcipher_alg *alg)
 238{
 239        return alg->ivsize;
 240}
 241
 242/**
 243 * crypto_skcipher_ivsize() - obtain IV size
 244 * @tfm: cipher handle
 245 *
 246 * The size of the IV for the skcipher referenced by the cipher handle is
 247 * returned. This IV size may be zero if the cipher does not need an IV.
 248 *
 249 * Return: IV size in bytes
 250 */
 251static inline unsigned int crypto_skcipher_ivsize(struct crypto_skcipher *tfm)
 252{
 253        return crypto_skcipher_alg(tfm)->ivsize;
 254}
 255
 256static inline unsigned int crypto_sync_skcipher_ivsize(
 257        struct crypto_sync_skcipher *tfm)
 258{
 259        return crypto_skcipher_ivsize(&tfm->base);
 260}
 261
 262/**
 263 * crypto_skcipher_blocksize() - obtain block size of cipher
 264 * @tfm: cipher handle
 265 *
 266 * The block size for the skcipher referenced with the cipher handle is
 267 * returned. The caller may use that information to allocate appropriate
 268 * memory for the data returned by the encryption or decryption operation
 269 *
 270 * Return: block size of cipher
 271 */
 272static inline unsigned int crypto_skcipher_blocksize(
 273        struct crypto_skcipher *tfm)
 274{
 275        return crypto_tfm_alg_blocksize(crypto_skcipher_tfm(tfm));
 276}
 277
 278static inline unsigned int crypto_skcipher_alg_chunksize(
 279        struct skcipher_alg *alg)
 280{
 281        return alg->chunksize;
 282}
 283
 284/**
 285 * crypto_skcipher_chunksize() - obtain chunk size
 286 * @tfm: cipher handle
 287 *
 288 * The block size is set to one for ciphers such as CTR.  However,
 289 * you still need to provide incremental updates in multiples of
 290 * the underlying block size as the IV does not have sub-block
 291 * granularity.  This is known in this API as the chunk size.
 292 *
 293 * Return: chunk size in bytes
 294 */
 295static inline unsigned int crypto_skcipher_chunksize(
 296        struct crypto_skcipher *tfm)
 297{
 298        return crypto_skcipher_alg_chunksize(crypto_skcipher_alg(tfm));
 299}
 300
 301static inline unsigned int crypto_sync_skcipher_blocksize(
 302        struct crypto_sync_skcipher *tfm)
 303{
 304        return crypto_skcipher_blocksize(&tfm->base);
 305}
 306
 307static inline unsigned int crypto_skcipher_alignmask(
 308        struct crypto_skcipher *tfm)
 309{
 310        return crypto_tfm_alg_alignmask(crypto_skcipher_tfm(tfm));
 311}
 312
 313static inline u32 crypto_skcipher_get_flags(struct crypto_skcipher *tfm)
 314{
 315        return crypto_tfm_get_flags(crypto_skcipher_tfm(tfm));
 316}
 317
 318static inline void crypto_skcipher_set_flags(struct crypto_skcipher *tfm,
 319                                               u32 flags)
 320{
 321        crypto_tfm_set_flags(crypto_skcipher_tfm(tfm), flags);
 322}
 323
 324static inline void crypto_skcipher_clear_flags(struct crypto_skcipher *tfm,
 325                                                 u32 flags)
 326{
 327        crypto_tfm_clear_flags(crypto_skcipher_tfm(tfm), flags);
 328}
 329
 330static inline u32 crypto_sync_skcipher_get_flags(
 331        struct crypto_sync_skcipher *tfm)
 332{
 333        return crypto_skcipher_get_flags(&tfm->base);
 334}
 335
 336static inline void crypto_sync_skcipher_set_flags(
 337        struct crypto_sync_skcipher *tfm, u32 flags)
 338{
 339        crypto_skcipher_set_flags(&tfm->base, flags);
 340}
 341
 342static inline void crypto_sync_skcipher_clear_flags(
 343        struct crypto_sync_skcipher *tfm, u32 flags)
 344{
 345        crypto_skcipher_clear_flags(&tfm->base, flags);
 346}
 347
 348/**
 349 * crypto_skcipher_setkey() - set key for cipher
 350 * @tfm: cipher handle
 351 * @key: buffer holding the key
 352 * @keylen: length of the key in bytes
 353 *
 354 * The caller provided key is set for the skcipher referenced by the cipher
 355 * handle.
 356 *
 357 * Note, the key length determines the cipher type. Many block ciphers implement
 358 * different cipher modes depending on the key size, such as AES-128 vs AES-192
 359 * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
 360 * is performed.
 361 *
 362 * Return: 0 if the setting of the key was successful; < 0 if an error occurred
 363 */
 364int crypto_skcipher_setkey(struct crypto_skcipher *tfm,
 365                           const u8 *key, unsigned int keylen);
 366
 367static inline int crypto_sync_skcipher_setkey(struct crypto_sync_skcipher *tfm,
 368                                         const u8 *key, unsigned int keylen)
 369{
 370        return crypto_skcipher_setkey(&tfm->base, key, keylen);
 371}
 372
 373static inline unsigned int crypto_skcipher_min_keysize(
 374        struct crypto_skcipher *tfm)
 375{
 376        return crypto_skcipher_alg(tfm)->min_keysize;
 377}
 378
 379static inline unsigned int crypto_skcipher_max_keysize(
 380        struct crypto_skcipher *tfm)
 381{
 382        return crypto_skcipher_alg(tfm)->max_keysize;
 383}
 384
 385/**
 386 * crypto_skcipher_reqtfm() - obtain cipher handle from request
 387 * @req: skcipher_request out of which the cipher handle is to be obtained
 388 *
 389 * Return the crypto_skcipher handle when furnishing an skcipher_request
 390 * data structure.
 391 *
 392 * Return: crypto_skcipher handle
 393 */
 394static inline struct crypto_skcipher *crypto_skcipher_reqtfm(
 395        struct skcipher_request *req)
 396{
 397        return __crypto_skcipher_cast(req->base.tfm);
 398}
 399
 400static inline struct crypto_sync_skcipher *crypto_sync_skcipher_reqtfm(
 401        struct skcipher_request *req)
 402{
 403        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 404
 405        return container_of(tfm, struct crypto_sync_skcipher, base);
 406}
 407
 408/**
 409 * crypto_skcipher_encrypt() - encrypt plaintext
 410 * @req: reference to the skcipher_request handle that holds all information
 411 *       needed to perform the cipher operation
 412 *
 413 * Encrypt plaintext data using the skcipher_request handle. That data
 414 * structure and how it is filled with data is discussed with the
 415 * skcipher_request_* functions.
 416 *
 417 * Return: 0 if the cipher operation was successful; < 0 if an error occurred
 418 */
 419int crypto_skcipher_encrypt(struct skcipher_request *req);
 420
 421/**
 422 * crypto_skcipher_decrypt() - decrypt ciphertext
 423 * @req: reference to the skcipher_request handle that holds all information
 424 *       needed to perform the cipher operation
 425 *
 426 * Decrypt ciphertext data using the skcipher_request handle. That data
 427 * structure and how it is filled with data is discussed with the
 428 * skcipher_request_* functions.
 429 *
 430 * Return: 0 if the cipher operation was successful; < 0 if an error occurred
 431 */
 432int crypto_skcipher_decrypt(struct skcipher_request *req);
 433
 434/**
 435 * DOC: Symmetric Key Cipher Request Handle
 436 *
 437 * The skcipher_request data structure contains all pointers to data
 438 * required for the symmetric key cipher operation. This includes the cipher
 439 * handle (which can be used by multiple skcipher_request instances), pointer
 440 * to plaintext and ciphertext, asynchronous callback function, etc. It acts
 441 * as a handle to the skcipher_request_* API calls in a similar way as
 442 * skcipher handle to the crypto_skcipher_* API calls.
 443 */
 444
 445/**
 446 * crypto_skcipher_reqsize() - obtain size of the request data structure
 447 * @tfm: cipher handle
 448 *
 449 * Return: number of bytes
 450 */
 451static inline unsigned int crypto_skcipher_reqsize(struct crypto_skcipher *tfm)
 452{
 453        return tfm->reqsize;
 454}
 455
 456/**
 457 * skcipher_request_set_tfm() - update cipher handle reference in request
 458 * @req: request handle to be modified
 459 * @tfm: cipher handle that shall be added to the request handle
 460 *
 461 * Allow the caller to replace the existing skcipher handle in the request
 462 * data structure with a different one.
 463 */
 464static inline void skcipher_request_set_tfm(struct skcipher_request *req,
 465                                            struct crypto_skcipher *tfm)
 466{
 467        req->base.tfm = crypto_skcipher_tfm(tfm);
 468}
 469
 470static inline void skcipher_request_set_sync_tfm(struct skcipher_request *req,
 471                                            struct crypto_sync_skcipher *tfm)
 472{
 473        skcipher_request_set_tfm(req, &tfm->base);
 474}
 475
 476static inline struct skcipher_request *skcipher_request_cast(
 477        struct crypto_async_request *req)
 478{
 479        return container_of(req, struct skcipher_request, base);
 480}
 481
 482/**
 483 * skcipher_request_alloc() - allocate request data structure
 484 * @tfm: cipher handle to be registered with the request
 485 * @gfp: memory allocation flag that is handed to kmalloc by the API call.
 486 *
 487 * Allocate the request data structure that must be used with the skcipher
 488 * encrypt and decrypt API calls. During the allocation, the provided skcipher
 489 * handle is registered in the request data structure.
 490 *
 491 * Return: allocated request handle in case of success, or NULL if out of memory
 492 */
 493static inline struct skcipher_request *skcipher_request_alloc(
 494        struct crypto_skcipher *tfm, gfp_t gfp)
 495{
 496        struct skcipher_request *req;
 497
 498        req = kmalloc(sizeof(struct skcipher_request) +
 499                      crypto_skcipher_reqsize(tfm), gfp);
 500
 501        if (likely(req))
 502                skcipher_request_set_tfm(req, tfm);
 503
 504        return req;
 505}
 506
 507/**
 508 * skcipher_request_free() - zeroize and free request data structure
 509 * @req: request data structure cipher handle to be freed
 510 */
 511static inline void skcipher_request_free(struct skcipher_request *req)
 512{
 513        kfree_sensitive(req);
 514}
 515
 516static inline void skcipher_request_zero(struct skcipher_request *req)
 517{
 518        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 519
 520        memzero_explicit(req, sizeof(*req) + crypto_skcipher_reqsize(tfm));
 521}
 522
 523/**
 524 * skcipher_request_set_callback() - set asynchronous callback function
 525 * @req: request handle
 526 * @flags: specify zero or an ORing of the flags
 527 *         CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
 528 *         increase the wait queue beyond the initial maximum size;
 529 *         CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
 530 * @compl: callback function pointer to be registered with the request handle
 531 * @data: The data pointer refers to memory that is not used by the kernel
 532 *        crypto API, but provided to the callback function for it to use. Here,
 533 *        the caller can provide a reference to memory the callback function can
 534 *        operate on. As the callback function is invoked asynchronously to the
 535 *        related functionality, it may need to access data structures of the
 536 *        related functionality which can be referenced using this pointer. The
 537 *        callback function can access the memory via the "data" field in the
 538 *        crypto_async_request data structure provided to the callback function.
 539 *
 540 * This function allows setting the callback function that is triggered once the
 541 * cipher operation completes.
 542 *
 543 * The callback function is registered with the skcipher_request handle and
 544 * must comply with the following template::
 545 *
 546 *      void callback_function(struct crypto_async_request *req, int error)
 547 */
 548static inline void skcipher_request_set_callback(struct skcipher_request *req,
 549                                                 u32 flags,
 550                                                 crypto_completion_t compl,
 551                                                 void *data)
 552{
 553        req->base.complete = compl;
 554        req->base.data = data;
 555        req->base.flags = flags;
 556}
 557
 558/**
 559 * skcipher_request_set_crypt() - set data buffers
 560 * @req: request handle
 561 * @src: source scatter / gather list
 562 * @dst: destination scatter / gather list
 563 * @cryptlen: number of bytes to process from @src
 564 * @iv: IV for the cipher operation which must comply with the IV size defined
 565 *      by crypto_skcipher_ivsize
 566 *
 567 * This function allows setting of the source data and destination data
 568 * scatter / gather lists.
 569 *
 570 * For encryption, the source is treated as the plaintext and the
 571 * destination is the ciphertext. For a decryption operation, the use is
 572 * reversed - the source is the ciphertext and the destination is the plaintext.
 573 */
 574static inline void skcipher_request_set_crypt(
 575        struct skcipher_request *req,
 576        struct scatterlist *src, struct scatterlist *dst,
 577        unsigned int cryptlen, void *iv)
 578{
 579        req->src = src;
 580        req->dst = dst;
 581        req->cryptlen = cryptlen;
 582        req->iv = iv;
 583}
 584
 585#endif  /* _CRYPTO_SKCIPHER_H */
 586
 587
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