linux/crypto/ctr.c
<<
>>
Prefs
   1/*
   2 * CTR: Counter mode
   3 *
   4 * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
   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#include <crypto/algapi.h>
  14#include <crypto/ctr.h>
  15#include <crypto/internal/skcipher.h>
  16#include <linux/err.h>
  17#include <linux/init.h>
  18#include <linux/kernel.h>
  19#include <linux/module.h>
  20#include <linux/random.h>
  21#include <linux/scatterlist.h>
  22#include <linux/slab.h>
  23
  24struct crypto_ctr_ctx {
  25        struct crypto_cipher *child;
  26};
  27
  28struct crypto_rfc3686_ctx {
  29        struct crypto_ablkcipher *child;
  30        u8 nonce[CTR_RFC3686_NONCE_SIZE];
  31};
  32
  33struct crypto_rfc3686_req_ctx {
  34        u8 iv[CTR_RFC3686_BLOCK_SIZE];
  35        struct ablkcipher_request subreq CRYPTO_MINALIGN_ATTR;
  36};
  37
  38static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
  39                             unsigned int keylen)
  40{
  41        struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent);
  42        struct crypto_cipher *child = ctx->child;
  43        int err;
  44
  45        crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
  46        crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
  47                                CRYPTO_TFM_REQ_MASK);
  48        err = crypto_cipher_setkey(child, key, keylen);
  49        crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
  50                             CRYPTO_TFM_RES_MASK);
  51
  52        return err;
  53}
  54
  55static void crypto_ctr_crypt_final(struct blkcipher_walk *walk,
  56                                   struct crypto_cipher *tfm)
  57{
  58        unsigned int bsize = crypto_cipher_blocksize(tfm);
  59        unsigned long alignmask = crypto_cipher_alignmask(tfm);
  60        u8 *ctrblk = walk->iv;
  61        u8 tmp[bsize + alignmask];
  62        u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
  63        u8 *src = walk->src.virt.addr;
  64        u8 *dst = walk->dst.virt.addr;
  65        unsigned int nbytes = walk->nbytes;
  66
  67        crypto_cipher_encrypt_one(tfm, keystream, ctrblk);
  68        crypto_xor(keystream, src, nbytes);
  69        memcpy(dst, keystream, nbytes);
  70
  71        crypto_inc(ctrblk, bsize);
  72}
  73
  74static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
  75                                    struct crypto_cipher *tfm)
  76{
  77        void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
  78                   crypto_cipher_alg(tfm)->cia_encrypt;
  79        unsigned int bsize = crypto_cipher_blocksize(tfm);
  80        u8 *ctrblk = walk->iv;
  81        u8 *src = walk->src.virt.addr;
  82        u8 *dst = walk->dst.virt.addr;
  83        unsigned int nbytes = walk->nbytes;
  84
  85        do {
  86                /* create keystream */
  87                fn(crypto_cipher_tfm(tfm), dst, ctrblk);
  88                crypto_xor(dst, src, bsize);
  89
  90                /* increment counter in counterblock */
  91                crypto_inc(ctrblk, bsize);
  92
  93                src += bsize;
  94                dst += bsize;
  95        } while ((nbytes -= bsize) >= bsize);
  96
  97        return nbytes;
  98}
  99
 100static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
 101                                    struct crypto_cipher *tfm)
 102{
 103        void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
 104                   crypto_cipher_alg(tfm)->cia_encrypt;
 105        unsigned int bsize = crypto_cipher_blocksize(tfm);
 106        unsigned long alignmask = crypto_cipher_alignmask(tfm);
 107        unsigned int nbytes = walk->nbytes;
 108        u8 *ctrblk = walk->iv;
 109        u8 *src = walk->src.virt.addr;
 110        u8 tmp[bsize + alignmask];
 111        u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
 112
 113        do {
 114                /* create keystream */
 115                fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
 116                crypto_xor(src, keystream, bsize);
 117
 118                /* increment counter in counterblock */
 119                crypto_inc(ctrblk, bsize);
 120
 121                src += bsize;
 122        } while ((nbytes -= bsize) >= bsize);
 123
 124        return nbytes;
 125}
 126
 127static int crypto_ctr_crypt(struct blkcipher_desc *desc,
 128                              struct scatterlist *dst, struct scatterlist *src,
 129                              unsigned int nbytes)
 130{
 131        struct blkcipher_walk walk;
 132        struct crypto_blkcipher *tfm = desc->tfm;
 133        struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
 134        struct crypto_cipher *child = ctx->child;
 135        unsigned int bsize = crypto_cipher_blocksize(child);
 136        int err;
 137
 138        blkcipher_walk_init(&walk, dst, src, nbytes);
 139        err = blkcipher_walk_virt_block(desc, &walk, bsize);
 140
 141        while (walk.nbytes >= bsize) {
 142                if (walk.src.virt.addr == walk.dst.virt.addr)
 143                        nbytes = crypto_ctr_crypt_inplace(&walk, child);
 144                else
 145                        nbytes = crypto_ctr_crypt_segment(&walk, child);
 146
 147                err = blkcipher_walk_done(desc, &walk, nbytes);
 148        }
 149
 150        if (walk.nbytes) {
 151                crypto_ctr_crypt_final(&walk, child);
 152                err = blkcipher_walk_done(desc, &walk, 0);
 153        }
 154
 155        return err;
 156}
 157
 158static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
 159{
 160        struct crypto_instance *inst = (void *)tfm->__crt_alg;
 161        struct crypto_spawn *spawn = crypto_instance_ctx(inst);
 162        struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
 163        struct crypto_cipher *cipher;
 164
 165        cipher = crypto_spawn_cipher(spawn);
 166        if (IS_ERR(cipher))
 167                return PTR_ERR(cipher);
 168
 169        ctx->child = cipher;
 170
 171        return 0;
 172}
 173
 174static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm)
 175{
 176        struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
 177
 178        crypto_free_cipher(ctx->child);
 179}
 180
 181static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
 182{
 183        struct crypto_instance *inst;
 184        struct crypto_alg *alg;
 185        int err;
 186
 187        err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
 188        if (err)
 189                return ERR_PTR(err);
 190
 191        alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
 192                                  CRYPTO_ALG_TYPE_MASK);
 193        if (IS_ERR(alg))
 194                return ERR_CAST(alg);
 195
 196        /* Block size must be >= 4 bytes. */
 197        err = -EINVAL;
 198        if (alg->cra_blocksize < 4)
 199                goto out_put_alg;
 200
 201        /* If this is false we'd fail the alignment of crypto_inc. */
 202        if (alg->cra_blocksize % 4)
 203                goto out_put_alg;
 204
 205        inst = crypto_alloc_instance("ctr", alg);
 206        if (IS_ERR(inst))
 207                goto out;
 208
 209        inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
 210        inst->alg.cra_priority = alg->cra_priority;
 211        inst->alg.cra_blocksize = 1;
 212        inst->alg.cra_alignmask = alg->cra_alignmask | (__alignof__(u32) - 1);
 213        inst->alg.cra_type = &crypto_blkcipher_type;
 214
 215        inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
 216        inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
 217        inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
 218
 219        inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx);
 220
 221        inst->alg.cra_init = crypto_ctr_init_tfm;
 222        inst->alg.cra_exit = crypto_ctr_exit_tfm;
 223
 224        inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
 225        inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
 226        inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;
 227
 228        inst->alg.cra_blkcipher.geniv = "chainiv";
 229
 230out:
 231        crypto_mod_put(alg);
 232        return inst;
 233
 234out_put_alg:
 235        inst = ERR_PTR(err);
 236        goto out;
 237}
 238
 239static void crypto_ctr_free(struct crypto_instance *inst)
 240{
 241        crypto_drop_spawn(crypto_instance_ctx(inst));
 242        kfree(inst);
 243}
 244
 245static struct crypto_template crypto_ctr_tmpl = {
 246        .name = "ctr",
 247        .alloc = crypto_ctr_alloc,
 248        .free = crypto_ctr_free,
 249        .module = THIS_MODULE,
 250};
 251
 252static int crypto_rfc3686_setkey(struct crypto_ablkcipher *parent,
 253                                 const u8 *key, unsigned int keylen)
 254{
 255        struct crypto_rfc3686_ctx *ctx = crypto_ablkcipher_ctx(parent);
 256        struct crypto_ablkcipher *child = ctx->child;
 257        int err;
 258
 259        /* the nonce is stored in bytes at end of key */
 260        if (keylen < CTR_RFC3686_NONCE_SIZE)
 261                return -EINVAL;
 262
 263        memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE),
 264               CTR_RFC3686_NONCE_SIZE);
 265
 266        keylen -= CTR_RFC3686_NONCE_SIZE;
 267
 268        crypto_ablkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
 269        crypto_ablkcipher_set_flags(child, crypto_ablkcipher_get_flags(parent) &
 270                                    CRYPTO_TFM_REQ_MASK);
 271        err = crypto_ablkcipher_setkey(child, key, keylen);
 272        crypto_ablkcipher_set_flags(parent, crypto_ablkcipher_get_flags(child) &
 273                                    CRYPTO_TFM_RES_MASK);
 274
 275        return err;
 276}
 277
 278static int crypto_rfc3686_crypt(struct ablkcipher_request *req)
 279{
 280        struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);
 281        struct crypto_rfc3686_ctx *ctx = crypto_ablkcipher_ctx(tfm);
 282        struct crypto_ablkcipher *child = ctx->child;
 283        unsigned long align = crypto_ablkcipher_alignmask(tfm);
 284        struct crypto_rfc3686_req_ctx *rctx =
 285                (void *)PTR_ALIGN((u8 *)ablkcipher_request_ctx(req), align + 1);
 286        struct ablkcipher_request *subreq = &rctx->subreq;
 287        u8 *iv = rctx->iv;
 288
 289        /* set up counter block */
 290        memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE);
 291        memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->info, CTR_RFC3686_IV_SIZE);
 292
 293        /* initialize counter portion of counter block */
 294        *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) =
 295                cpu_to_be32(1);
 296
 297        ablkcipher_request_set_tfm(subreq, child);
 298        ablkcipher_request_set_callback(subreq, req->base.flags,
 299                                        req->base.complete, req->base.data);
 300        ablkcipher_request_set_crypt(subreq, req->src, req->dst, req->nbytes,
 301                                     iv);
 302
 303        return crypto_ablkcipher_encrypt(subreq);
 304}
 305
 306static int crypto_rfc3686_init_tfm(struct crypto_tfm *tfm)
 307{
 308        struct crypto_instance *inst = (void *)tfm->__crt_alg;
 309        struct crypto_skcipher_spawn *spawn = crypto_instance_ctx(inst);
 310        struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
 311        struct crypto_ablkcipher *cipher;
 312        unsigned long align;
 313
 314        cipher = crypto_spawn_skcipher(spawn);
 315        if (IS_ERR(cipher))
 316                return PTR_ERR(cipher);
 317
 318        ctx->child = cipher;
 319
 320        align = crypto_tfm_alg_alignmask(tfm);
 321        align &= ~(crypto_tfm_ctx_alignment() - 1);
 322        tfm->crt_ablkcipher.reqsize = align +
 323                sizeof(struct crypto_rfc3686_req_ctx) +
 324                crypto_ablkcipher_reqsize(cipher);
 325
 326        return 0;
 327}
 328
 329static void crypto_rfc3686_exit_tfm(struct crypto_tfm *tfm)
 330{
 331        struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
 332
 333        crypto_free_ablkcipher(ctx->child);
 334}
 335
 336static struct crypto_instance *crypto_rfc3686_alloc(struct rtattr **tb)
 337{
 338        struct crypto_attr_type *algt;
 339        struct crypto_instance *inst;
 340        struct crypto_alg *alg;
 341        struct crypto_skcipher_spawn *spawn;
 342        const char *cipher_name;
 343        int err;
 344
 345        algt = crypto_get_attr_type(tb);
 346        if (IS_ERR(algt))
 347                return ERR_CAST(algt);
 348
 349        if ((algt->type ^ CRYPTO_ALG_TYPE_BLKCIPHER) & algt->mask)
 350                return ERR_PTR(-EINVAL);
 351
 352        cipher_name = crypto_attr_alg_name(tb[1]);
 353        if (IS_ERR(cipher_name))
 354                return ERR_CAST(cipher_name);
 355
 356        inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 357        if (!inst)
 358                return ERR_PTR(-ENOMEM);
 359
 360        spawn = crypto_instance_ctx(inst);
 361
 362        crypto_set_skcipher_spawn(spawn, inst);
 363        err = crypto_grab_skcipher(spawn, cipher_name, 0,
 364                                   crypto_requires_sync(algt->type,
 365                                                        algt->mask));
 366        if (err)
 367                goto err_free_inst;
 368
 369        alg = crypto_skcipher_spawn_alg(spawn);
 370
 371        /* We only support 16-byte blocks. */
 372        err = -EINVAL;
 373        if (alg->cra_ablkcipher.ivsize != CTR_RFC3686_BLOCK_SIZE)
 374                goto err_drop_spawn;
 375
 376        /* Not a stream cipher? */
 377        if (alg->cra_blocksize != 1)
 378                goto err_drop_spawn;
 379
 380        err = -ENAMETOOLONG;
 381        if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME, "rfc3686(%s)",
 382                     alg->cra_name) >= CRYPTO_MAX_ALG_NAME)
 383                goto err_drop_spawn;
 384        if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 385                     "rfc3686(%s)", alg->cra_driver_name) >=
 386                        CRYPTO_MAX_ALG_NAME)
 387                goto err_drop_spawn;
 388
 389        inst->alg.cra_priority = alg->cra_priority;
 390        inst->alg.cra_blocksize = 1;
 391        inst->alg.cra_alignmask = alg->cra_alignmask;
 392
 393        inst->alg.cra_flags = CRYPTO_ALG_TYPE_ABLKCIPHER |
 394                              (alg->cra_flags & CRYPTO_ALG_ASYNC);
 395        inst->alg.cra_type = &crypto_ablkcipher_type;
 396
 397        inst->alg.cra_ablkcipher.ivsize = CTR_RFC3686_IV_SIZE;
 398        inst->alg.cra_ablkcipher.min_keysize =
 399                alg->cra_ablkcipher.min_keysize + CTR_RFC3686_NONCE_SIZE;
 400        inst->alg.cra_ablkcipher.max_keysize =
 401                alg->cra_ablkcipher.max_keysize + CTR_RFC3686_NONCE_SIZE;
 402
 403        inst->alg.cra_ablkcipher.geniv = "seqiv";
 404
 405        inst->alg.cra_ablkcipher.setkey = crypto_rfc3686_setkey;
 406        inst->alg.cra_ablkcipher.encrypt = crypto_rfc3686_crypt;
 407        inst->alg.cra_ablkcipher.decrypt = crypto_rfc3686_crypt;
 408
 409        inst->alg.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);
 410
 411        inst->alg.cra_init = crypto_rfc3686_init_tfm;
 412        inst->alg.cra_exit = crypto_rfc3686_exit_tfm;
 413
 414        return inst;
 415
 416err_drop_spawn:
 417        crypto_drop_skcipher(spawn);
 418err_free_inst:
 419        kfree(inst);
 420        return ERR_PTR(err);
 421}
 422
 423static void crypto_rfc3686_free(struct crypto_instance *inst)
 424{
 425        struct crypto_skcipher_spawn *spawn = crypto_instance_ctx(inst);
 426
 427        crypto_drop_skcipher(spawn);
 428        kfree(inst);
 429}
 430
 431static struct crypto_template crypto_rfc3686_tmpl = {
 432        .name = "rfc3686",
 433        .alloc = crypto_rfc3686_alloc,
 434        .free = crypto_rfc3686_free,
 435        .module = THIS_MODULE,
 436};
 437
 438static int __init crypto_ctr_module_init(void)
 439{
 440        int err;
 441
 442        err = crypto_register_template(&crypto_ctr_tmpl);
 443        if (err)
 444                goto out;
 445
 446        err = crypto_register_template(&crypto_rfc3686_tmpl);
 447        if (err)
 448                goto out_drop_ctr;
 449
 450out:
 451        return err;
 452
 453out_drop_ctr:
 454        crypto_unregister_template(&crypto_ctr_tmpl);
 455        goto out;
 456}
 457
 458static void __exit crypto_ctr_module_exit(void)
 459{
 460        crypto_unregister_template(&crypto_rfc3686_tmpl);
 461        crypto_unregister_template(&crypto_ctr_tmpl);
 462}
 463
 464module_init(crypto_ctr_module_init);
 465module_exit(crypto_ctr_module_exit);
 466
 467MODULE_LICENSE("GPL");
 468MODULE_DESCRIPTION("CTR Counter block mode");
 469MODULE_ALIAS("rfc3686");
 470
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.