linux/drivers/md/dm-crypt.c
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   1/*
   2 * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
   3 * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
   4 * Copyright (C) 2006-2008 Red Hat, Inc. All rights reserved.
   5 *
   6 * This file is released under the GPL.
   7 */
   8
   9#include <linux/completion.h>
  10#include <linux/err.h>
  11#include <linux/module.h>
  12#include <linux/init.h>
  13#include <linux/kernel.h>
  14#include <linux/bio.h>
  15#include <linux/blkdev.h>
  16#include <linux/mempool.h>
  17#include <linux/slab.h>
  18#include <linux/crypto.h>
  19#include <linux/workqueue.h>
  20#include <linux/backing-dev.h>
  21#include <asm/atomic.h>
  22#include <linux/scatterlist.h>
  23#include <asm/page.h>
  24#include <asm/unaligned.h>
  25
  26#include <linux/device-mapper.h>
  27
  28#define DM_MSG_PREFIX "crypt"
  29#define MESG_STR(x) x, sizeof(x)
  30
  31/*
  32 * context holding the current state of a multi-part conversion
  33 */
  34struct convert_context {
  35        struct completion restart;
  36        struct bio *bio_in;
  37        struct bio *bio_out;
  38        unsigned int offset_in;
  39        unsigned int offset_out;
  40        unsigned int idx_in;
  41        unsigned int idx_out;
  42        sector_t sector;
  43        atomic_t pending;
  44};
  45
  46/*
  47 * per bio private data
  48 */
  49struct dm_crypt_io {
  50        struct dm_target *target;
  51        struct bio *base_bio;
  52        struct work_struct work;
  53
  54        struct convert_context ctx;
  55
  56        atomic_t pending;
  57        int error;
  58        sector_t sector;
  59        struct dm_crypt_io *base_io;
  60};
  61
  62struct dm_crypt_request {
  63        struct scatterlist sg_in;
  64        struct scatterlist sg_out;
  65};
  66
  67struct crypt_config;
  68
  69struct crypt_iv_operations {
  70        int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
  71                   const char *opts);
  72        void (*dtr)(struct crypt_config *cc);
  73        const char *(*status)(struct crypt_config *cc);
  74        int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
  75};
  76
  77/*
  78 * Crypt: maps a linear range of a block device
  79 * and encrypts / decrypts at the same time.
  80 */
  81enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
  82struct crypt_config {
  83        struct dm_dev *dev;
  84        sector_t start;
  85
  86        /*
  87         * pool for per bio private data, crypto requests and
  88         * encryption requeusts/buffer pages
  89         */
  90        mempool_t *io_pool;
  91        mempool_t *req_pool;
  92        mempool_t *page_pool;
  93        struct bio_set *bs;
  94
  95        struct workqueue_struct *io_queue;
  96        struct workqueue_struct *crypt_queue;
  97
  98        /*
  99         * crypto related data
 100         */
 101        struct crypt_iv_operations *iv_gen_ops;
 102        char *iv_mode;
 103        union {
 104                struct crypto_cipher *essiv_tfm;
 105                int benbi_shift;
 106        } iv_gen_private;
 107        sector_t iv_offset;
 108        unsigned int iv_size;
 109
 110        /*
 111         * Layout of each crypto request:
 112         *
 113         *   struct ablkcipher_request
 114         *      context
 115         *      padding
 116         *   struct dm_crypt_request
 117         *      padding
 118         *   IV
 119         *
 120         * The padding is added so that dm_crypt_request and the IV are
 121         * correctly aligned.
 122         */
 123        unsigned int dmreq_start;
 124        struct ablkcipher_request *req;
 125
 126        char cipher[CRYPTO_MAX_ALG_NAME];
 127        char chainmode[CRYPTO_MAX_ALG_NAME];
 128        struct crypto_ablkcipher *tfm;
 129        unsigned long flags;
 130        unsigned int key_size;
 131        u8 key[0];
 132};
 133
 134#define MIN_IOS        16
 135#define MIN_POOL_PAGES 32
 136#define MIN_BIO_PAGES  8
 137
 138static struct kmem_cache *_crypt_io_pool;
 139
 140static void clone_init(struct dm_crypt_io *, struct bio *);
 141static void kcryptd_queue_crypt(struct dm_crypt_io *io);
 142
 143/*
 144 * Different IV generation algorithms:
 145 *
 146 * plain: the initial vector is the 32-bit little-endian version of the sector
 147 *        number, padded with zeros if necessary.
 148 *
 149 * essiv: "encrypted sector|salt initial vector", the sector number is
 150 *        encrypted with the bulk cipher using a salt as key. The salt
 151 *        should be derived from the bulk cipher's key via hashing.
 152 *
 153 * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
 154 *        (needed for LRW-32-AES and possible other narrow block modes)
 155 *
 156 * null: the initial vector is always zero.  Provides compatibility with
 157 *       obsolete loop_fish2 devices.  Do not use for new devices.
 158 *
 159 * plumb: unimplemented, see:
 160 * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
 161 */
 162
 163static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 164{
 165        memset(iv, 0, cc->iv_size);
 166        *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
 167
 168        return 0;
 169}
 170
 171static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 172                              const char *opts)
 173{
 174        struct crypto_cipher *essiv_tfm;
 175        struct crypto_hash *hash_tfm;
 176        struct hash_desc desc;
 177        struct scatterlist sg;
 178        unsigned int saltsize;
 179        u8 *salt;
 180        int err;
 181
 182        if (opts == NULL) {
 183                ti->error = "Digest algorithm missing for ESSIV mode";
 184                return -EINVAL;
 185        }
 186
 187        /* Hash the cipher key with the given hash algorithm */
 188        hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
 189        if (IS_ERR(hash_tfm)) {
 190                ti->error = "Error initializing ESSIV hash";
 191                return PTR_ERR(hash_tfm);
 192        }
 193
 194        saltsize = crypto_hash_digestsize(hash_tfm);
 195        salt = kmalloc(saltsize, GFP_KERNEL);
 196        if (salt == NULL) {
 197                ti->error = "Error kmallocing salt storage in ESSIV";
 198                crypto_free_hash(hash_tfm);
 199                return -ENOMEM;
 200        }
 201
 202        sg_init_one(&sg, cc->key, cc->key_size);
 203        desc.tfm = hash_tfm;
 204        desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 205        err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
 206        crypto_free_hash(hash_tfm);
 207
 208        if (err) {
 209                ti->error = "Error calculating hash in ESSIV";
 210                kfree(salt);
 211                return err;
 212        }
 213
 214        /* Setup the essiv_tfm with the given salt */
 215        essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 216        if (IS_ERR(essiv_tfm)) {
 217                ti->error = "Error allocating crypto tfm for ESSIV";
 218                kfree(salt);
 219                return PTR_ERR(essiv_tfm);
 220        }
 221        if (crypto_cipher_blocksize(essiv_tfm) !=
 222            crypto_ablkcipher_ivsize(cc->tfm)) {
 223                ti->error = "Block size of ESSIV cipher does "
 224                            "not match IV size of block cipher";
 225                crypto_free_cipher(essiv_tfm);
 226                kfree(salt);
 227                return -EINVAL;
 228        }
 229        err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
 230        if (err) {
 231                ti->error = "Failed to set key for ESSIV cipher";
 232                crypto_free_cipher(essiv_tfm);
 233                kfree(salt);
 234                return err;
 235        }
 236        kfree(salt);
 237
 238        cc->iv_gen_private.essiv_tfm = essiv_tfm;
 239        return 0;
 240}
 241
 242static void crypt_iv_essiv_dtr(struct crypt_config *cc)
 243{
 244        crypto_free_cipher(cc->iv_gen_private.essiv_tfm);
 245        cc->iv_gen_private.essiv_tfm = NULL;
 246}
 247
 248static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 249{
 250        memset(iv, 0, cc->iv_size);
 251        *(u64 *)iv = cpu_to_le64(sector);
 252        crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv);
 253        return 0;
 254}
 255
 256static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
 257                              const char *opts)
 258{
 259        unsigned bs = crypto_ablkcipher_blocksize(cc->tfm);
 260        int log = ilog2(bs);
 261
 262        /* we need to calculate how far we must shift the sector count
 263         * to get the cipher block count, we use this shift in _gen */
 264
 265        if (1 << log != bs) {
 266                ti->error = "cypher blocksize is not a power of 2";
 267                return -EINVAL;
 268        }
 269
 270        if (log > 9) {
 271                ti->error = "cypher blocksize is > 512";
 272                return -EINVAL;
 273        }
 274
 275        cc->iv_gen_private.benbi_shift = 9 - log;
 276
 277        return 0;
 278}
 279
 280static void crypt_iv_benbi_dtr(struct crypt_config *cc)
 281{
 282}
 283
 284static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 285{
 286        __be64 val;
 287
 288        memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */
 289
 290        val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi_shift) + 1);
 291        put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));
 292
 293        return 0;
 294}
 295
 296static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 297{
 298        memset(iv, 0, cc->iv_size);
 299
 300        return 0;
 301}
 302
 303static struct crypt_iv_operations crypt_iv_plain_ops = {
 304        .generator = crypt_iv_plain_gen
 305};
 306
 307static struct crypt_iv_operations crypt_iv_essiv_ops = {
 308        .ctr       = crypt_iv_essiv_ctr,
 309        .dtr       = crypt_iv_essiv_dtr,
 310        .generator = crypt_iv_essiv_gen
 311};
 312
 313static struct crypt_iv_operations crypt_iv_benbi_ops = {
 314        .ctr       = crypt_iv_benbi_ctr,
 315        .dtr       = crypt_iv_benbi_dtr,
 316        .generator = crypt_iv_benbi_gen
 317};
 318
 319static struct crypt_iv_operations crypt_iv_null_ops = {
 320        .generator = crypt_iv_null_gen
 321};
 322
 323static void crypt_convert_init(struct crypt_config *cc,
 324                               struct convert_context *ctx,
 325                               struct bio *bio_out, struct bio *bio_in,
 326                               sector_t sector)
 327{
 328        ctx->bio_in = bio_in;
 329        ctx->bio_out = bio_out;
 330        ctx->offset_in = 0;
 331        ctx->offset_out = 0;
 332        ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
 333        ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
 334        ctx->sector = sector + cc->iv_offset;
 335        init_completion(&ctx->restart);
 336}
 337
 338static int crypt_convert_block(struct crypt_config *cc,
 339                               struct convert_context *ctx,
 340                               struct ablkcipher_request *req)
 341{
 342        struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
 343        struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
 344        struct dm_crypt_request *dmreq;
 345        u8 *iv;
 346        int r = 0;
 347
 348        dmreq = (struct dm_crypt_request *)((char *)req + cc->dmreq_start);
 349        iv = (u8 *)ALIGN((unsigned long)(dmreq + 1),
 350                         crypto_ablkcipher_alignmask(cc->tfm) + 1);
 351
 352        sg_init_table(&dmreq->sg_in, 1);
 353        sg_set_page(&dmreq->sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT,
 354                    bv_in->bv_offset + ctx->offset_in);
 355
 356        sg_init_table(&dmreq->sg_out, 1);
 357        sg_set_page(&dmreq->sg_out, bv_out->bv_page, 1 << SECTOR_SHIFT,
 358                    bv_out->bv_offset + ctx->offset_out);
 359
 360        ctx->offset_in += 1 << SECTOR_SHIFT;
 361        if (ctx->offset_in >= bv_in->bv_len) {
 362                ctx->offset_in = 0;
 363                ctx->idx_in++;
 364        }
 365
 366        ctx->offset_out += 1 << SECTOR_SHIFT;
 367        if (ctx->offset_out >= bv_out->bv_len) {
 368                ctx->offset_out = 0;
 369                ctx->idx_out++;
 370        }
 371
 372        if (cc->iv_gen_ops) {
 373                r = cc->iv_gen_ops->generator(cc, iv, ctx->sector);
 374                if (r < 0)
 375                        return r;
 376        }
 377
 378        ablkcipher_request_set_crypt(req, &dmreq->sg_in, &dmreq->sg_out,
 379                                     1 << SECTOR_SHIFT, iv);
 380
 381        if (bio_data_dir(ctx->bio_in) == WRITE)
 382                r = crypto_ablkcipher_encrypt(req);
 383        else
 384                r = crypto_ablkcipher_decrypt(req);
 385
 386        return r;
 387}
 388
 389static void kcryptd_async_done(struct crypto_async_request *async_req,
 390                               int error);
 391static void crypt_alloc_req(struct crypt_config *cc,
 392                            struct convert_context *ctx)
 393{
 394        if (!cc->req)
 395                cc->req = mempool_alloc(cc->req_pool, GFP_NOIO);
 396        ablkcipher_request_set_tfm(cc->req, cc->tfm);
 397        ablkcipher_request_set_callback(cc->req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 398                                             CRYPTO_TFM_REQ_MAY_SLEEP,
 399                                             kcryptd_async_done, ctx);
 400}
 401
 402/*
 403 * Encrypt / decrypt data from one bio to another one (can be the same one)
 404 */
 405static int crypt_convert(struct crypt_config *cc,
 406                         struct convert_context *ctx)
 407{
 408        int r;
 409
 410        atomic_set(&ctx->pending, 1);
 411
 412        while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
 413              ctx->idx_out < ctx->bio_out->bi_vcnt) {
 414
 415                crypt_alloc_req(cc, ctx);
 416
 417                atomic_inc(&ctx->pending);
 418
 419                r = crypt_convert_block(cc, ctx, cc->req);
 420
 421                switch (r) {
 422                /* async */
 423                case -EBUSY:
 424                        wait_for_completion(&ctx->restart);
 425                        INIT_COMPLETION(ctx->restart);
 426                        /* fall through*/
 427                case -EINPROGRESS:
 428                        cc->req = NULL;
 429                        ctx->sector++;
 430                        continue;
 431
 432                /* sync */
 433                case 0:
 434                        atomic_dec(&ctx->pending);
 435                        ctx->sector++;
 436                        cond_resched();
 437                        continue;
 438
 439                /* error */
 440                default:
 441                        atomic_dec(&ctx->pending);
 442                        return r;
 443                }
 444        }
 445
 446        return 0;
 447}
 448
 449static void dm_crypt_bio_destructor(struct bio *bio)
 450{
 451        struct dm_crypt_io *io = bio->bi_private;
 452        struct crypt_config *cc = io->target->private;
 453
 454        bio_free(bio, cc->bs);
 455}
 456
 457/*
 458 * Generate a new unfragmented bio with the given size
 459 * This should never violate the device limitations
 460 * May return a smaller bio when running out of pages, indicated by
 461 * *out_of_pages set to 1.
 462 */
 463static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size,
 464                                      unsigned *out_of_pages)
 465{
 466        struct crypt_config *cc = io->target->private;
 467        struct bio *clone;
 468        unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 469        gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
 470        unsigned i, len;
 471        struct page *page;
 472
 473        clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
 474        if (!clone)
 475                return NULL;
 476
 477        clone_init(io, clone);
 478        *out_of_pages = 0;
 479
 480        for (i = 0; i < nr_iovecs; i++) {
 481                page = mempool_alloc(cc->page_pool, gfp_mask);
 482                if (!page) {
 483                        *out_of_pages = 1;
 484                        break;
 485                }
 486
 487                /*
 488                 * if additional pages cannot be allocated without waiting,
 489                 * return a partially allocated bio, the caller will then try
 490                 * to allocate additional bios while submitting this partial bio
 491                 */
 492                if (i == (MIN_BIO_PAGES - 1))
 493                        gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
 494
 495                len = (size > PAGE_SIZE) ? PAGE_SIZE : size;
 496
 497                if (!bio_add_page(clone, page, len, 0)) {
 498                        mempool_free(page, cc->page_pool);
 499                        break;
 500                }
 501
 502                size -= len;
 503        }
 504
 505        if (!clone->bi_size) {
 506                bio_put(clone);
 507                return NULL;
 508        }
 509
 510        return clone;
 511}
 512
 513static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
 514{
 515        unsigned int i;
 516        struct bio_vec *bv;
 517
 518        for (i = 0; i < clone->bi_vcnt; i++) {
 519                bv = bio_iovec_idx(clone, i);
 520                BUG_ON(!bv->bv_page);
 521                mempool_free(bv->bv_page, cc->page_pool);
 522                bv->bv_page = NULL;
 523        }
 524}
 525
 526static struct dm_crypt_io *crypt_io_alloc(struct dm_target *ti,
 527                                          struct bio *bio, sector_t sector)
 528{
 529        struct crypt_config *cc = ti->private;
 530        struct dm_crypt_io *io;
 531
 532        io = mempool_alloc(cc->io_pool, GFP_NOIO);
 533        io->target = ti;
 534        io->base_bio = bio;
 535        io->sector = sector;
 536        io->error = 0;
 537        io->base_io = NULL;
 538        atomic_set(&io->pending, 0);
 539
 540        return io;
 541}
 542
 543static void crypt_inc_pending(struct dm_crypt_io *io)
 544{
 545        atomic_inc(&io->pending);
 546}
 547
 548/*
 549 * One of the bios was finished. Check for completion of
 550 * the whole request and correctly clean up the buffer.
 551 * If base_io is set, wait for the last fragment to complete.
 552 */
 553static void crypt_dec_pending(struct dm_crypt_io *io)
 554{
 555        struct crypt_config *cc = io->target->private;
 556
 557        if (!atomic_dec_and_test(&io->pending))
 558                return;
 559
 560        if (likely(!io->base_io))
 561                bio_endio(io->base_bio, io->error);
 562        else {
 563                if (io->error && !io->base_io->error)
 564                        io->base_io->error = io->error;
 565                crypt_dec_pending(io->base_io);
 566        }
 567
 568        mempool_free(io, cc->io_pool);
 569}
 570
 571/*
 572 * kcryptd/kcryptd_io:
 573 *
 574 * Needed because it would be very unwise to do decryption in an
 575 * interrupt context.
 576 *
 577 * kcryptd performs the actual encryption or decryption.
 578 *
 579 * kcryptd_io performs the IO submission.
 580 *
 581 * They must be separated as otherwise the final stages could be
 582 * starved by new requests which can block in the first stages due
 583 * to memory allocation.
 584 */
 585static void crypt_endio(struct bio *clone, int error)
 586{
 587        struct dm_crypt_io *io = clone->bi_private;
 588        struct crypt_config *cc = io->target->private;
 589        unsigned rw = bio_data_dir(clone);
 590
 591        if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error))
 592                error = -EIO;
 593
 594        /*
 595         * free the processed pages
 596         */
 597        if (rw == WRITE)
 598                crypt_free_buffer_pages(cc, clone);
 599
 600        bio_put(clone);
 601
 602        if (rw == READ && !error) {
 603                kcryptd_queue_crypt(io);
 604                return;
 605        }
 606
 607        if (unlikely(error))
 608                io->error = error;
 609
 610        crypt_dec_pending(io);
 611}
 612
 613static void clone_init(struct dm_crypt_io *io, struct bio *clone)
 614{
 615        struct crypt_config *cc = io->target->private;
 616
 617        clone->bi_private = io;
 618        clone->bi_end_io  = crypt_endio;
 619        clone->bi_bdev    = cc->dev->bdev;
 620        clone->bi_rw      = io->base_bio->bi_rw;
 621        clone->bi_destructor = dm_crypt_bio_destructor;
 622}
 623
 624static void kcryptd_io_read(struct dm_crypt_io *io)
 625{
 626        struct crypt_config *cc = io->target->private;
 627        struct bio *base_bio = io->base_bio;
 628        struct bio *clone;
 629
 630        crypt_inc_pending(io);
 631
 632        /*
 633         * The block layer might modify the bvec array, so always
 634         * copy the required bvecs because we need the original
 635         * one in order to decrypt the whole bio data *afterwards*.
 636         */
 637        clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
 638        if (unlikely(!clone)) {
 639                io->error = -ENOMEM;
 640                crypt_dec_pending(io);
 641                return;
 642        }
 643
 644        clone_init(io, clone);
 645        clone->bi_idx = 0;
 646        clone->bi_vcnt = bio_segments(base_bio);
 647        clone->bi_size = base_bio->bi_size;
 648        clone->bi_sector = cc->start + io->sector;
 649        memcpy(clone->bi_io_vec, bio_iovec(base_bio),
 650               sizeof(struct bio_vec) * clone->bi_vcnt);
 651
 652        generic_make_request(clone);
 653}
 654
 655static void kcryptd_io_write(struct dm_crypt_io *io)
 656{
 657        struct bio *clone = io->ctx.bio_out;
 658        generic_make_request(clone);
 659}
 660
 661static void kcryptd_io(struct work_struct *work)
 662{
 663        struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
 664
 665        if (bio_data_dir(io->base_bio) == READ)
 666                kcryptd_io_read(io);
 667        else
 668                kcryptd_io_write(io);
 669}
 670
 671static void kcryptd_queue_io(struct dm_crypt_io *io)
 672{
 673        struct crypt_config *cc = io->target->private;
 674
 675        INIT_WORK(&io->work, kcryptd_io);
 676        queue_work(cc->io_queue, &io->work);
 677}
 678
 679static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io,
 680                                          int error, int async)
 681{
 682        struct bio *clone = io->ctx.bio_out;
 683        struct crypt_config *cc = io->target->private;
 684
 685        if (unlikely(error < 0)) {
 686                crypt_free_buffer_pages(cc, clone);
 687                bio_put(clone);
 688                io->error = -EIO;
 689                crypt_dec_pending(io);
 690                return;
 691        }
 692
 693        /* crypt_convert should have filled the clone bio */
 694        BUG_ON(io->ctx.idx_out < clone->bi_vcnt);
 695
 696        clone->bi_sector = cc->start + io->sector;
 697
 698        if (async)
 699                kcryptd_queue_io(io);
 700        else
 701                generic_make_request(clone);
 702}
 703
 704static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
 705{
 706        struct crypt_config *cc = io->target->private;
 707        struct bio *clone;
 708        struct dm_crypt_io *new_io;
 709        int crypt_finished;
 710        unsigned out_of_pages = 0;
 711        unsigned remaining = io->base_bio->bi_size;
 712        sector_t sector = io->sector;
 713        int r;
 714
 715        /*
 716         * Prevent io from disappearing until this function completes.
 717         */
 718        crypt_inc_pending(io);
 719        crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, sector);
 720
 721        /*
 722         * The allocated buffers can be smaller than the whole bio,
 723         * so repeat the whole process until all the data can be handled.
 724         */
 725        while (remaining) {
 726                clone = crypt_alloc_buffer(io, remaining, &out_of_pages);
 727                if (unlikely(!clone)) {
 728                        io->error = -ENOMEM;
 729                        break;
 730                }
 731
 732                io->ctx.bio_out = clone;
 733                io->ctx.idx_out = 0;
 734
 735                remaining -= clone->bi_size;
 736                sector += bio_sectors(clone);
 737
 738                crypt_inc_pending(io);
 739                r = crypt_convert(cc, &io->ctx);
 740                crypt_finished = atomic_dec_and_test(&io->ctx.pending);
 741
 742                /* Encryption was already finished, submit io now */
 743                if (crypt_finished) {
 744                        kcryptd_crypt_write_io_submit(io, r, 0);
 745
 746                        /*
 747                         * If there was an error, do not try next fragments.
 748                         * For async, error is processed in async handler.
 749                         */
 750                        if (unlikely(r < 0))
 751                                break;
 752
 753                        io->sector = sector;
 754                }
 755
 756                /*
 757                 * Out of memory -> run queues
 758                 * But don't wait if split was due to the io size restriction
 759                 */
 760                if (unlikely(out_of_pages))
 761                        congestion_wait(WRITE, HZ/100);
 762
 763                /*
 764                 * With async crypto it is unsafe to share the crypto context
 765                 * between fragments, so switch to a new dm_crypt_io structure.
 766                 */
 767                if (unlikely(!crypt_finished && remaining)) {
 768                        new_io = crypt_io_alloc(io->target, io->base_bio,
 769                                                sector);
 770                        crypt_inc_pending(new_io);
 771                        crypt_convert_init(cc, &new_io->ctx, NULL,
 772                                           io->base_bio, sector);
 773                        new_io->ctx.idx_in = io->ctx.idx_in;
 774                        new_io->ctx.offset_in = io->ctx.offset_in;
 775
 776                        /*
 777                         * Fragments after the first use the base_io
 778                         * pending count.
 779                         */
 780                        if (!io->base_io)
 781                                new_io->base_io = io;
 782                        else {
 783                                new_io->base_io = io->base_io;
 784                                crypt_inc_pending(io->base_io);
 785                                crypt_dec_pending(io);
 786                        }
 787
 788                        io = new_io;
 789                }
 790        }
 791
 792        crypt_dec_pending(io);
 793}
 794
 795static void kcryptd_crypt_read_done(struct dm_crypt_io *io, int error)
 796{
 797        if (unlikely(error < 0))
 798                io->error = -EIO;
 799
 800        crypt_dec_pending(io);
 801}
 802
 803static void kcryptd_crypt_read_convert(struct dm_crypt_io *io)
 804{
 805        struct crypt_config *cc = io->target->private;
 806        int r = 0;
 807
 808        crypt_inc_pending(io);
 809
 810        crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio,
 811                           io->sector);
 812
 813        r = crypt_convert(cc, &io->ctx);
 814
 815        if (atomic_dec_and_test(&io->ctx.pending))
 816                kcryptd_crypt_read_done(io, r);
 817
 818        crypt_dec_pending(io);
 819}
 820
 821static void kcryptd_async_done(struct crypto_async_request *async_req,
 822                               int error)
 823{
 824        struct convert_context *ctx = async_req->data;
 825        struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx);
 826        struct crypt_config *cc = io->target->private;
 827
 828        if (error == -EINPROGRESS) {
 829                complete(&ctx->restart);
 830                return;
 831        }
 832
 833        mempool_free(ablkcipher_request_cast(async_req), cc->req_pool);
 834
 835        if (!atomic_dec_and_test(&ctx->pending))
 836                return;
 837
 838        if (bio_data_dir(io->base_bio) == READ)
 839                kcryptd_crypt_read_done(io, error);
 840        else
 841                kcryptd_crypt_write_io_submit(io, error, 1);
 842}
 843
 844static void kcryptd_crypt(struct work_struct *work)
 845{
 846        struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
 847
 848        if (bio_data_dir(io->base_bio) == READ)
 849                kcryptd_crypt_read_convert(io);
 850        else
 851                kcryptd_crypt_write_convert(io);
 852}
 853
 854static void kcryptd_queue_crypt(struct dm_crypt_io *io)
 855{
 856        struct crypt_config *cc = io->target->private;
 857
 858        INIT_WORK(&io->work, kcryptd_crypt);
 859        queue_work(cc->crypt_queue, &io->work);
 860}
 861
 862/*
 863 * Decode key from its hex representation
 864 */
 865static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
 866{
 867        char buffer[3];
 868        char *endp;
 869        unsigned int i;
 870
 871        buffer[2] = '\0';
 872
 873        for (i = 0; i < size; i++) {
 874                buffer[0] = *hex++;
 875                buffer[1] = *hex++;
 876
 877                key[i] = (u8)simple_strtoul(buffer, &endp, 16);
 878
 879                if (endp != &buffer[2])
 880                        return -EINVAL;
 881        }
 882
 883        if (*hex != '\0')
 884                return -EINVAL;
 885
 886        return 0;
 887}
 888
 889/*
 890 * Encode key into its hex representation
 891 */
 892static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
 893{
 894        unsigned int i;
 895
 896        for (i = 0; i < size; i++) {
 897                sprintf(hex, "%02x", *key);
 898                hex += 2;
 899                key++;
 900        }
 901}
 902
 903static int crypt_set_key(struct crypt_config *cc, char *key)
 904{
 905        unsigned key_size = strlen(key) >> 1;
 906
 907        if (cc->key_size && cc->key_size != key_size)
 908                return -EINVAL;
 909
 910        cc->key_size = key_size; /* initial settings */
 911
 912        if ((!key_size && strcmp(key, "-")) ||
 913           (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
 914                return -EINVAL;
 915
 916        set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 917
 918        return 0;
 919}
 920
 921static int crypt_wipe_key(struct crypt_config *cc)
 922{
 923        clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 924        memset(&cc->key, 0, cc->key_size * sizeof(u8));
 925        return 0;
 926}
 927
 928/*
 929 * Construct an encryption mapping:
 930 * <cipher> <key> <iv_offset> <dev_path> <start>
 931 */
 932static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 933{
 934        struct crypt_config *cc;
 935        struct crypto_ablkcipher *tfm;
 936        char *tmp;
 937        char *cipher;
 938        char *chainmode;
 939        char *ivmode;
 940        char *ivopts;
 941        unsigned int key_size;
 942        unsigned long long tmpll;
 943
 944        if (argc != 5) {
 945                ti->error = "Not enough arguments";
 946                return -EINVAL;
 947        }
 948
 949        tmp = argv[0];
 950        cipher = strsep(&tmp, "-");
 951        chainmode = strsep(&tmp, "-");
 952        ivopts = strsep(&tmp, "-");
 953        ivmode = strsep(&ivopts, ":");
 954
 955        if (tmp)
 956                DMWARN("Unexpected additional cipher options");
 957
 958        key_size = strlen(argv[1]) >> 1;
 959
 960        cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
 961        if (cc == NULL) {
 962                ti->error =
 963                        "Cannot allocate transparent encryption context";
 964                return -ENOMEM;
 965        }
 966
 967        if (crypt_set_key(cc, argv[1])) {
 968                ti->error = "Error decoding key";
 969                goto bad_cipher;
 970        }
 971
 972        /* Compatiblity mode for old dm-crypt cipher strings */
 973        if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
 974                chainmode = "cbc";
 975                ivmode = "plain";
 976        }
 977
 978        if (strcmp(chainmode, "ecb") && !ivmode) {
 979                ti->error = "This chaining mode requires an IV mechanism";
 980                goto bad_cipher;
 981        }
 982
 983        if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)",
 984                     chainmode, cipher) >= CRYPTO_MAX_ALG_NAME) {
 985                ti->error = "Chain mode + cipher name is too long";
 986                goto bad_cipher;
 987        }
 988
 989        tfm = crypto_alloc_ablkcipher(cc->cipher, 0, 0);
 990        if (IS_ERR(tfm)) {
 991                ti->error = "Error allocating crypto tfm";
 992                goto bad_cipher;
 993        }
 994
 995        strcpy(cc->cipher, cipher);
 996        strcpy(cc->chainmode, chainmode);
 997        cc->tfm = tfm;
 998
 999        /*
1000         * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
1001         * See comments at iv code
1002         */
1003
1004        if (ivmode == NULL)
1005                cc->iv_gen_ops = NULL;
1006        else if (strcmp(ivmode, "plain") == 0)
1007                cc->iv_gen_ops = &crypt_iv_plain_ops;
1008        else if (strcmp(ivmode, "essiv") == 0)
1009                cc->iv_gen_ops = &crypt_iv_essiv_ops;
1010        else if (strcmp(ivmode, "benbi") == 0)
1011                cc->iv_gen_ops = &crypt_iv_benbi_ops;
1012        else if (strcmp(ivmode, "null") == 0)
1013                cc->iv_gen_ops = &crypt_iv_null_ops;
1014        else {
1015                ti->error = "Invalid IV mode";
1016                goto bad_ivmode;
1017        }
1018
1019        if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
1020            cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
1021                goto bad_ivmode;
1022
1023        cc->iv_size = crypto_ablkcipher_ivsize(tfm);
1024        if (cc->iv_size)
1025                /* at least a 64 bit sector number should fit in our buffer */
1026                cc->iv_size = max(cc->iv_size,
1027                                  (unsigned int)(sizeof(u64) / sizeof(u8)));
1028        else {
1029                if (cc->iv_gen_ops) {
1030                        DMWARN("Selected cipher does not support IVs");
1031                        if (cc->iv_gen_ops->dtr)
1032                                cc->iv_gen_ops->dtr(cc);
1033                        cc->iv_gen_ops = NULL;
1034                }
1035        }
1036
1037        cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
1038        if (!cc->io_pool) {
1039                ti->error = "Cannot allocate crypt io mempool";
1040                goto bad_slab_pool;
1041        }
1042
1043        cc->dmreq_start = sizeof(struct ablkcipher_request);
1044        cc->dmreq_start += crypto_ablkcipher_reqsize(tfm);
1045        cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment());
1046        cc->dmreq_start += crypto_ablkcipher_alignmask(tfm) &
1047                           ~(crypto_tfm_ctx_alignment() - 1);
1048
1049        cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start +
1050                        sizeof(struct dm_crypt_request) + cc->iv_size);
1051        if (!cc->req_pool) {
1052                ti->error = "Cannot allocate crypt request mempool";
1053                goto bad_req_pool;
1054        }
1055        cc->req = NULL;
1056
1057        cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
1058        if (!cc->page_pool) {
1059                ti->error = "Cannot allocate page mempool";
1060                goto bad_page_pool;
1061        }
1062
1063        cc->bs = bioset_create(MIN_IOS, MIN_IOS);
1064        if (!cc->bs) {
1065                ti->error = "Cannot allocate crypt bioset";
1066                goto bad_bs;
1067        }
1068
1069        if (crypto_ablkcipher_setkey(tfm, cc->key, key_size) < 0) {
1070                ti->error = "Error setting key";
1071                goto bad_device;
1072        }
1073
1074        if (sscanf(argv[2], "%llu", &tmpll) != 1) {
1075                ti->error = "Invalid iv_offset sector";
1076                goto bad_device;
1077        }
1078        cc->iv_offset = tmpll;
1079
1080        if (sscanf(argv[4], "%llu", &tmpll) != 1) {
1081                ti->error = "Invalid device sector";
1082                goto bad_device;
1083        }
1084        cc->start = tmpll;
1085
1086        if (dm_get_device(ti, argv[3], cc->start, ti->len,
1087                          dm_table_get_mode(ti->table), &cc->dev)) {
1088                ti->error = "Device lookup failed";
1089                goto bad_device;
1090        }
1091
1092        if (ivmode && cc->iv_gen_ops) {
1093                if (ivopts)
1094                        *(ivopts - 1) = ':';
1095                cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
1096                if (!cc->iv_mode) {
1097                        ti->error = "Error kmallocing iv_mode string";
1098                        goto bad_ivmode_string;
1099                }
1100                strcpy(cc->iv_mode, ivmode);
1101        } else
1102                cc->iv_mode = NULL;
1103
1104        cc->io_queue = create_singlethread_workqueue("kcryptd_io");
1105        if (!cc->io_queue) {
1106                ti->error = "Couldn't create kcryptd io queue";
1107                goto bad_io_queue;
1108        }
1109
1110        cc->crypt_queue = create_singlethread_workqueue("kcryptd");
1111        if (!cc->crypt_queue) {
1112                ti->error = "Couldn't create kcryptd queue";
1113                goto bad_crypt_queue;
1114        }
1115
1116        ti->private = cc;
1117        return 0;
1118
1119bad_crypt_queue:
1120        destroy_workqueue(cc->io_queue);
1121bad_io_queue:
1122        kfree(cc->iv_mode);
1123bad_ivmode_string:
1124        dm_put_device(ti, cc->dev);
1125bad_device:
1126        bioset_free(cc->bs);
1127bad_bs:
1128        mempool_destroy(cc->page_pool);
1129bad_page_pool:
1130        mempool_destroy(cc->req_pool);
1131bad_req_pool:
1132        mempool_destroy(cc->io_pool);
1133bad_slab_pool:
1134        if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
1135                cc->iv_gen_ops->dtr(cc);
1136bad_ivmode:
1137        crypto_free_ablkcipher(tfm);
1138bad_cipher:
1139        /* Must zero key material before freeing */
1140        memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
1141        kfree(cc);
1142        return -EINVAL;
1143}
1144
1145static void crypt_dtr(struct dm_target *ti)
1146{
1147        struct crypt_config *cc = (struct crypt_config *) ti->private;
1148
1149        destroy_workqueue(cc->io_queue);
1150        destroy_workqueue(cc->crypt_queue);
1151
1152        if (cc->req)
1153                mempool_free(cc->req, cc->req_pool);
1154
1155        bioset_free(cc->bs);
1156        mempool_destroy(cc->page_pool);
1157        mempool_destroy(cc->req_pool);
1158        mempool_destroy(cc->io_pool);
1159
1160        kfree(cc->iv_mode);
1161        if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
1162                cc->iv_gen_ops->dtr(cc);
1163        crypto_free_ablkcipher(cc->tfm);
1164        dm_put_device(ti, cc->dev);
1165
1166        /* Must zero key material before freeing */
1167        memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
1168        kfree(cc);
1169}
1170
1171static int crypt_map(struct dm_target *ti, struct bio *bio,
1172                     union map_info *map_context)
1173{
1174        struct dm_crypt_io *io;
1175
1176        io = crypt_io_alloc(ti, bio, bio->bi_sector - ti->begin);
1177
1178        if (bio_data_dir(io->base_bio) == READ)
1179                kcryptd_queue_io(io);
1180        else
1181                kcryptd_queue_crypt(io);
1182
1183        return DM_MAPIO_SUBMITTED;
1184}
1185
1186static int crypt_status(struct dm_target *ti, status_type_t type,
1187                        char *result, unsigned int maxlen)
1188{
1189        struct crypt_config *cc = (struct crypt_config *) ti->private;
1190        unsigned int sz = 0;
1191
1192        switch (type) {
1193        case STATUSTYPE_INFO:
1194                result[0] = '\0';
1195                break;
1196
1197        case STATUSTYPE_TABLE:
1198                if (cc->iv_mode)
1199                        DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
1200                               cc->iv_mode);
1201                else
1202                        DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
1203
1204                if (cc->key_size > 0) {
1205                        if ((maxlen - sz) < ((cc->key_size << 1) + 1))
1206                                return -ENOMEM;
1207
1208                        crypt_encode_key(result + sz, cc->key, cc->key_size);
1209                        sz += cc->key_size << 1;
1210                } else {
1211                        if (sz >= maxlen)
1212                                return -ENOMEM;
1213                        result[sz++] = '-';
1214                }
1215
1216                DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
1217                                cc->dev->name, (unsigned long long)cc->start);
1218                break;
1219        }
1220        return 0;
1221}
1222
1223static void crypt_postsuspend(struct dm_target *ti)
1224{
1225        struct crypt_config *cc = ti->private;
1226
1227        set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1228}
1229
1230static int crypt_preresume(struct dm_target *ti)
1231{
1232        struct crypt_config *cc = ti->private;
1233
1234        if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
1235                DMERR("aborting resume - crypt key is not set.");
1236                return -EAGAIN;
1237        }
1238
1239        return 0;
1240}
1241
1242static void crypt_resume(struct dm_target *ti)
1243{
1244        struct crypt_config *cc = ti->private;
1245
1246        clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1247}
1248
1249/* Message interface
1250 *      key set <key>
1251 *      key wipe
1252 */
1253static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
1254{
1255        struct crypt_config *cc = ti->private;
1256
1257        if (argc < 2)
1258                goto error;
1259
1260        if (!strnicmp(argv[0], MESG_STR("key"))) {
1261                if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
1262                        DMWARN("not suspended during key manipulation.");
1263                        return -EINVAL;
1264                }
1265                if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
1266                        return crypt_set_key(cc, argv[2]);
1267                if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
1268                        return crypt_wipe_key(cc);
1269        }
1270
1271error:
1272        DMWARN("unrecognised message received.");
1273        return -EINVAL;
1274}
1275
1276static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
1277                       struct bio_vec *biovec, int max_size)
1278{
1279        struct crypt_config *cc = ti->private;
1280        struct request_queue *q = bdev_get_queue(cc->dev->bdev);
1281
1282        if (!q->merge_bvec_fn)
1283                return max_size;
1284
1285        bvm->bi_bdev = cc->dev->bdev;
1286        bvm->bi_sector = cc->start + bvm->bi_sector - ti->begin;
1287
1288        return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
1289}
1290
1291static struct target_type crypt_target = {
1292        .name   = "crypt",
1293        .version= {1, 6, 0},
1294        .module = THIS_MODULE,
1295        .ctr    = crypt_ctr,
1296        .dtr    = crypt_dtr,
1297        .map    = crypt_map,
1298        .status = crypt_status,
1299        .postsuspend = crypt_postsuspend,
1300        .preresume = crypt_preresume,
1301        .resume = crypt_resume,
1302        .message = crypt_message,
1303        .merge  = crypt_merge,
1304};
1305
1306static int __init dm_crypt_init(void)
1307{
1308        int r;
1309
1310        _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
1311        if (!_crypt_io_pool)
1312                return -ENOMEM;
1313
1314        r = dm_register_target(&crypt_target);
1315        if (r < 0) {
1316                DMERR("register failed %d", r);
1317                kmem_cache_destroy(_crypt_io_pool);
1318        }
1319
1320        return r;
1321}
1322
1323static void __exit dm_crypt_exit(void)
1324{
1325        int r = dm_unregister_target(&crypt_target);
1326
1327        if (r < 0)
1328                DMERR("unregister failed %d", r);
1329
1330        kmem_cache_destroy(_crypt_io_pool);
1331}
1332
1333module_init(dm_crypt_init);
1334module_exit(dm_crypt_exit);
1335
1336MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
1337MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
1338MODULE_LICENSE("GPL");
1339