drivers/md/dm-crypt.c

   1 /*
   2  * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
   3  * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
   4  * Copyright (C) 2006 Red Hat, Inc. All rights reserved.
   5  *
   6  * This file is released under the GPL.
   7  */
   8
   9 #include <linux/err.h>
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/bio.h>
  14 #include <linux/blkdev.h>
  15 #include <linux/mempool.h>
  16 #include <linux/slab.h>
  17 #include <linux/crypto.h>
  18 #include <linux/workqueue.h>
  19 #include <linux/backing-dev.h>
  20 #include <asm/atomic.h>
  21 #include <linux/scatterlist.h>
  22 #include <asm/page.h>
  23 #include <asm/unaligned.h>
  24
  25 #include "dm.h"
  26
  27 #define DM_MSG_PREFIX "crypt"
  28 #define MESG_STR(x) x, sizeof(x)
  29
  30 /*
  31  * per bio private data
  32  */
  33 struct dm_crypt_io {
  34         struct dm_target *target;
  35         struct bio *base_bio;
  36         struct work_struct work;
  37         atomic_t pending;
  38         int error;
  39         int post_process;
  40 };
  41
  42 /*
  43  * context holding the current state of a multi-part conversion
  44  */
  45 struct convert_context {
  46         struct bio *bio_in;
  47         struct bio *bio_out;
  48         unsigned int offset_in;
  49         unsigned int offset_out;
  50         unsigned int idx_in;
  51         unsigned int idx_out;
  52         sector_t sector;
  53         int write;
  54 };
  55
  56 struct crypt_config;
  57
  58 struct crypt_iv_operations {
  59         int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
  60                    const char *opts);
  61         void (*dtr)(struct crypt_config *cc);
  62         const char *(*status)(struct crypt_config *cc);
  63         int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
  64 };
  65
  66 /*
  67  * Crypt: maps a linear range of a block device
  68  * and encrypts / decrypts at the same time.
  69  */
  70 enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
  71 struct crypt_config {
  72         struct dm_dev *dev;
  73         sector_t start;
  74
  75         /*
  76          * pool for per bio private data and
  77          * for encryption buffer pages
  78          */
  79         mempool_t *io_pool;
  80         mempool_t *page_pool;
  81         struct bio_set *bs;
  82
  83         /*
  84          * crypto related data
  85          */
  86         struct crypt_iv_operations *iv_gen_ops;
  87         char *iv_mode;
  88         union {
  89                 struct crypto_cipher *essiv_tfm;
  90                 int benbi_shift;
  91         } iv_gen_private;
  92         sector_t iv_offset;
  93         unsigned int iv_size;
  94
  95         char cipher[CRYPTO_MAX_ALG_NAME];
  96         char chainmode[CRYPTO_MAX_ALG_NAME];
  97         struct crypto_blkcipher *tfm;
  98         unsigned long flags;
  99         unsigned int key_size;
 100         u8 key[0];
 101 };
 102
 103 #define MIN_IOS        16
 104 #define MIN_POOL_PAGES 32
 105 #define MIN_BIO_PAGES  8
 106
 107 static struct kmem_cache *_crypt_io_pool;
 108
 109 static void clone_init(struct dm_crypt_io *, struct bio *);
 110
 111 /*
 112  * Different IV generation algorithms:
 113  *
 114  * plain: the initial vector is the 32-bit little-endian version of the sector
 115  *        number, padded with zeros if neccessary.
 116  *
 117  * essiv: "encrypted sector|salt initial vector", the sector number is
 118  *        encrypted with the bulk cipher using a salt as key. The salt
 119  *        should be derived from the bulk cipher's key via hashing.
 120  *
 121  * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
 122  *        (needed for LRW-32-AES and possible other narrow block modes)
 123  *
 124  * null: the initial vector is always zero.  Provides compatibility with
 125  *       obsolete loop_fish2 devices.  Do not use for new devices.
 126  *
 127  * plumb: unimplemented, see:
 128  * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
 129  */
 130
 131 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 132 {
 133         memset(iv, 0, cc->iv_size);
 134         *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
 135
 136         return 0;
 137 }
 138
 139 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 140                               const char *opts)
 141 {
 142         struct crypto_cipher *essiv_tfm;
 143         struct crypto_hash *hash_tfm;
 144         struct hash_desc desc;
 145         struct scatterlist sg;
 146         unsigned int saltsize;
 147         u8 *salt;
 148         int err;
 149
 150         if (opts == NULL) {
 151                 ti->error = "Digest algorithm missing for ESSIV mode";
 152                 return -EINVAL;
 153         }
 154
 155         /* Hash the cipher key with the given hash algorithm */
 156         hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
 157         if (IS_ERR(hash_tfm)) {
 158                 ti->error = "Error initializing ESSIV hash";
 159                 return PTR_ERR(hash_tfm);
 160         }
 161
 162         saltsize = crypto_hash_digestsize(hash_tfm);
 163         salt = kmalloc(saltsize, GFP_KERNEL);
 164         if (salt == NULL) {
 165                 ti->error = "Error kmallocing salt storage in ESSIV";
 166                 crypto_free_hash(hash_tfm);
 167                 return -ENOMEM;
 168         }
 169
 170         sg_set_buf(&sg, cc->key, cc->key_size);
 171         desc.tfm = hash_tfm;
 172         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 173         err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
 174         crypto_free_hash(hash_tfm);
 175
 176         if (err) {
 177                 ti->error = "Error calculating hash in ESSIV";
 178                 kfree(salt);
 179                 return err;
 180         }
 181
 182         /* Setup the essiv_tfm with the given salt */
 183         essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 184         if (IS_ERR(essiv_tfm)) {
 185                 ti->error = "Error allocating crypto tfm for ESSIV";
 186                 kfree(salt);
 187                 return PTR_ERR(essiv_tfm);
 188         }
 189         if (crypto_cipher_blocksize(essiv_tfm) !=
 190             crypto_blkcipher_ivsize(cc->tfm)) {
 191                 ti->error = "Block size of ESSIV cipher does "
 192                                 "not match IV size of block cipher";
 193                 crypto_free_cipher(essiv_tfm);
 194                 kfree(salt);
 195                 return -EINVAL;
 196         }
 197         err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
 198         if (err) {
 199                 ti->error = "Failed to set key for ESSIV cipher";
 200                 crypto_free_cipher(essiv_tfm);
 201                 kfree(salt);
 202                 return err;
 203         }
 204         kfree(salt);
 205
 206         cc->iv_gen_private.essiv_tfm = essiv_tfm;
 207         return 0;
 208 }
 209
 210 static void crypt_iv_essiv_dtr(struct crypt_config *cc)
 211 {
 212         crypto_free_cipher(cc->iv_gen_private.essiv_tfm);
 213         cc->iv_gen_private.essiv_tfm = NULL;
 214 }
 215
 216 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 217 {
 218         memset(iv, 0, cc->iv_size);
 219         *(u64 *)iv = cpu_to_le64(sector);
 220         crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv);
 221         return 0;
 222 }
 223
 224 static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
 225                               const char *opts)
 226 {
 227         unsigned int bs = crypto_blkcipher_blocksize(cc->tfm);
 228         int log = ilog2(bs);
 229
 230         /* we need to calculate how far we must shift the sector count
 231          * to get the cipher block count, we use this shift in _gen */
 232
 233         if (1 << log != bs) {
 234                 ti->error = "cypher blocksize is not a power of 2";
 235                 return -EINVAL;
 236         }
 237
 238         if (log > 9) {
 239                 ti->error = "cypher blocksize is > 512";
 240                 return -EINVAL;
 241         }
 242
 243         cc->iv_gen_private.benbi_shift = 9 - log;
 244
 245         return 0;
 246 }
 247
 248 static void crypt_iv_benbi_dtr(struct crypt_config *cc)
 249 {
 250 }
 251
 252 static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 253 {
 254         __be64 val;
 255
 256         memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */
 257
 258         val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi_shift) + 1);
 259         put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));
 260
 261         return 0;
 262 }
 263
 264 static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 265 {
 266         memset(iv, 0, cc->iv_size);
 267
 268         return 0;
 269 }
 270
 271 static struct crypt_iv_operations crypt_iv_plain_ops = {
 272         .generator = crypt_iv_plain_gen
 273 };
 274
 275 static struct crypt_iv_operations crypt_iv_essiv_ops = {
 276         .ctr       = crypt_iv_essiv_ctr,
 277         .dtr       = crypt_iv_essiv_dtr,
 278         .generator = crypt_iv_essiv_gen
 279 };
 280
 281 static struct crypt_iv_operations crypt_iv_benbi_ops = {
 282         .ctr       = crypt_iv_benbi_ctr,
 283         .dtr       = crypt_iv_benbi_dtr,
 284         .generator = crypt_iv_benbi_gen
 285 };
 286
 287 static struct crypt_iv_operations crypt_iv_null_ops = {
 288         .generator = crypt_iv_null_gen
 289 };
 290
 291 static int
 292 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
 293                           struct scatterlist *in, unsigned int length,
 294                           int write, sector_t sector)
 295 {
 296         u8 iv[cc->iv_size] __attribute__ ((aligned(__alignof__(u64))));
 297         struct blkcipher_desc desc = {
 298                 .tfm = cc->tfm,
 299                 .info = iv,
 300                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP,
 301         };
 302         int r;
 303
 304         if (cc->iv_gen_ops) {
 305                 r = cc->iv_gen_ops->generator(cc, iv, sector);
 306                 if (r < 0)
 307                         return r;
 308
 309                 if (write)
 310                         r = crypto_blkcipher_encrypt_iv(&desc, out, in, length);
 311                 else
 312                         r = crypto_blkcipher_decrypt_iv(&desc, out, in, length);
 313         } else {
 314                 if (write)
 315                         r = crypto_blkcipher_encrypt(&desc, out, in, length);
 316                 else
 317                         r = crypto_blkcipher_decrypt(&desc, out, in, length);
 318         }
 319
 320         return r;
 321 }
 322
 323 static void
 324 crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx,
 325                    struct bio *bio_out, struct bio *bio_in,
 326                    sector_t sector, int write)
 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         ctx->write = write;
 336 }
 337
 338 /*
 339  * Encrypt / decrypt data from one bio to another one (can be the same one)
 340  */
 341 static int crypt_convert(struct crypt_config *cc,
 342                          struct convert_context *ctx)
 343 {
 344         int r = 0;
 345
 346         while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
 347               ctx->idx_out < ctx->bio_out->bi_vcnt) {
 348                 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
 349                 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
 350                 struct scatterlist sg_in = {
 351                         .page = bv_in->bv_page,
 352                         .offset = bv_in->bv_offset + ctx->offset_in,
 353                         .length = 1 << SECTOR_SHIFT
 354                 };
 355                 struct scatterlist sg_out = {
 356                         .page = bv_out->bv_page,
 357                         .offset = bv_out->bv_offset + ctx->offset_out,
 358                         .length = 1 << SECTOR_SHIFT
 359                 };
 360
 361                 ctx->offset_in += sg_in.length;
 362                 if (ctx->offset_in >= bv_in->bv_len) {
 363                         ctx->offset_in = 0;
 364                         ctx->idx_in++;
 365                 }
 366
 367                 ctx->offset_out += sg_out.length;
 368                 if (ctx->offset_out >= bv_out->bv_len) {
 369                         ctx->offset_out = 0;
 370                         ctx->idx_out++;
 371                 }
 372
 373                 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
 374                                               ctx->write, ctx->sector);
 375                 if (r < 0)
 376                         break;
 377
 378                 ctx->sector++;
 379         }
 380
 381         return r;
 382 }
 383
 384  static void dm_crypt_bio_destructor(struct bio *bio)
 385  {
 386         struct dm_crypt_io *io = bio->bi_private;
 387         struct crypt_config *cc = io->target->private;
 388
 389         bio_free(bio, cc->bs);
 390  }
 391
 392 /*
 393  * Generate a new unfragmented bio with the given size
 394  * This should never violate the device limitations
 395  * May return a smaller bio when running out of pages
 396  */
 397 static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size)
 398 {
 399         struct crypt_config *cc = io->target->private;
 400         struct bio *clone;
 401         unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 402         gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
 403         unsigned int i;
 404
 405         clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
 406         if (!clone)
 407                 return NULL;
 408
 409         clone_init(io, clone);
 410
 411         for (i = 0; i < nr_iovecs; i++) {
 412                 struct bio_vec *bv = bio_iovec_idx(clone, i);
 413
 414                 bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
 415                 if (!bv->bv_page)
 416                         break;
 417
 418                 /*
 419                  * if additional pages cannot be allocated without waiting,
 420                  * return a partially allocated bio, the caller will then try
 421                  * to allocate additional bios while submitting this partial bio
 422                  */
 423                 if (i == (MIN_BIO_PAGES - 1))
 424                         gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
 425
 426                 bv->bv_offset = 0;
 427                 if (size > PAGE_SIZE)
 428                         bv->bv_len = PAGE_SIZE;
 429                 else
 430                         bv->bv_len = size;
 431
 432                 clone->bi_size += bv->bv_len;
 433                 clone->bi_vcnt++;
 434                 size -= bv->bv_len;
 435         }
 436
 437         if (!clone->bi_size) {
 438                 bio_put(clone);
 439                 return NULL;
 440         }
 441
 442         return clone;
 443 }
 444
 445 static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
 446 {
 447         unsigned int i;
 448         struct bio_vec *bv;
 449
 450         for (i = 0; i < clone->bi_vcnt; i++) {
 451                 bv = bio_iovec_idx(clone, i);
 452                 BUG_ON(!bv->bv_page);
 453                 mempool_free(bv->bv_page, cc->page_pool);
 454                 bv->bv_page = NULL;
 455         }
 456 }
 457
 458 /*
 459  * One of the bios was finished. Check for completion of
 460  * the whole request and correctly clean up the buffer.
 461  */
 462 static void dec_pending(struct dm_crypt_io *io, int error)
 463 {
 464         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 465
 466         if (error < 0)
 467                 io->error = error;
 468
 469         if (!atomic_dec_and_test(&io->pending))
 470                 return;
 471
 472         bio_endio(io->base_bio, io->error);
 473
 474         mempool_free(io, cc->io_pool);
 475 }
 476
 477 /*
 478  * kcryptd:
 479  *
 480  * Needed because it would be very unwise to do decryption in an
 481  * interrupt context.
 482  */
 483 static struct workqueue_struct *_kcryptd_workqueue;
 484 static void kcryptd_do_work(struct work_struct *work);
 485
 486 static void kcryptd_queue_io(struct dm_crypt_io *io)
 487 {
 488         INIT_WORK(&io->work, kcryptd_do_work);
 489         queue_work(_kcryptd_workqueue, &io->work);
 490 }
 491
 492 static void crypt_endio(struct bio *clone, int error)
 493 {
 494         struct dm_crypt_io *io = clone->bi_private;
 495         struct crypt_config *cc = io->target->private;
 496         unsigned read_io = bio_data_dir(clone) == READ;
 497
 498         /*
 499          * free the processed pages
 500          */
 501         if (!read_io) {
 502                 crypt_free_buffer_pages(cc, clone);
 503                 goto out;
 504         }
 505
 506         if (unlikely(!bio_flagged(clone, BIO_UPTODATE))) {
 507                 error = -EIO;
 508                 goto out;
 509         }
 510
 511         bio_put(clone);
 512         io->post_process = 1;
 513         kcryptd_queue_io(io);
 514         return;
 515
 516 out:
 517         bio_put(clone);
 518         dec_pending(io, error);
 519 }
 520
 521 static void clone_init(struct dm_crypt_io *io, struct bio *clone)
 522 {
 523         struct crypt_config *cc = io->target->private;
 524
 525         clone->bi_private = io;
 526         clone->bi_end_io  = crypt_endio;
 527         clone->bi_bdev    = cc->dev->bdev;
 528         clone->bi_rw      = io->base_bio->bi_rw;
 529         clone->bi_destructor = dm_crypt_bio_destructor;
 530 }
 531
 532 static void process_read(struct dm_crypt_io *io)
 533 {
 534         struct crypt_config *cc = io->target->private;
 535         struct bio *base_bio = io->base_bio;
 536         struct bio *clone;
 537         sector_t sector = base_bio->bi_sector - io->target->begin;
 538
 539         atomic_inc(&io->pending);
 540
 541         /*
 542          * The block layer might modify the bvec array, so always
 543          * copy the required bvecs because we need the original
 544          * one in order to decrypt the whole bio data *afterwards*.
 545          */
 546         clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
 547         if (unlikely(!clone)) {
 548                 dec_pending(io, -ENOMEM);
 549                 return;
 550         }
 551
 552         clone_init(io, clone);
 553         clone->bi_idx = 0;
 554         clone->bi_vcnt = bio_segments(base_bio);
 555         clone->bi_size = base_bio->bi_size;
 556         clone->bi_sector = cc->start + sector;
 557         memcpy(clone->bi_io_vec, bio_iovec(base_bio),
 558                sizeof(struct bio_vec) * clone->bi_vcnt);
 559
 560         generic_make_request(clone);
 561 }
 562
 563 static void process_write(struct dm_crypt_io *io)
 564 {
 565         struct crypt_config *cc = io->target->private;
 566         struct bio *base_bio = io->base_bio;
 567         struct bio *clone;
 568         struct convert_context ctx;
 569         unsigned remaining = base_bio->bi_size;
 570         sector_t sector = base_bio->bi_sector - io->target->begin;
 571
 572         atomic_inc(&io->pending);
 573
 574         crypt_convert_init(cc, &ctx, NULL, base_bio, sector, 1);
 575
 576         /*
 577          * The allocated buffers can be smaller than the whole bio,
 578          * so repeat the whole process until all the data can be handled.
 579          */
 580         while (remaining) {
 581                 clone = crypt_alloc_buffer(io, remaining);
 582                 if (unlikely(!clone)) {
 583                         dec_pending(io, -ENOMEM);
 584                         return;
 585                 }
 586
 587                 ctx.bio_out = clone;
 588                 ctx.idx_out = 0;
 589
 590                 if (unlikely(crypt_convert(cc, &ctx) < 0)) {
 591                         crypt_free_buffer_pages(cc, clone);
 592                         bio_put(clone);
 593                         dec_pending(io, -EIO);
 594                         return;
 595                 }
 596
 597                 /* crypt_convert should have filled the clone bio */
 598                 BUG_ON(ctx.idx_out < clone->bi_vcnt);
 599
 600                 clone->bi_sector = cc->start + sector;
 601                 remaining -= clone->bi_size;
 602                 sector += bio_sectors(clone);
 603
 604                 /* Grab another reference to the io struct
 605                  * before we kick off the request */
 606                 if (remaining)
 607                         atomic_inc(&io->pending);
 608
 609                 generic_make_request(clone);
 610
 611                 /* Do not reference clone after this - it
 612                  * may be gone already. */
 613
 614                 /* out of memory -> run queues */
 615                 if (remaining)
 616                         congestion_wait(WRITE, HZ/100);
 617         }
 618 }
 619
 620 static void process_read_endio(struct dm_crypt_io *io)
 621 {
 622         struct crypt_config *cc = io->target->private;
 623         struct convert_context ctx;
 624
 625         crypt_convert_init(cc, &ctx, io->base_bio, io->base_bio,
 626                            io->base_bio->bi_sector - io->target->begin, 0);
 627
 628         dec_pending(io, crypt_convert(cc, &ctx));
 629 }
 630
 631 static void kcryptd_do_work(struct work_struct *work)
 632 {
 633         struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
 634
 635         if (io->post_process)
 636                 process_read_endio(io);
 637         else if (bio_data_dir(io->base_bio) == READ)
 638                 process_read(io);
 639         else
 640                 process_write(io);
 641 }
 642
 643 /*
 644  * Decode key from its hex representation
 645  */
 646 static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
 647 {
 648         char buffer[3];
 649         char *endp;
 650         unsigned int i;
 651
 652         buffer[2] = '\0';
 653
 654         for (i = 0; i < size; i++) {
 655                 buffer[0] = *hex++;
 656                 buffer[1] = *hex++;
 657
 658                 key[i] = (u8)simple_strtoul(buffer, &endp, 16);
 659
 660                 if (endp != &buffer[2])
 661                         return -EINVAL;
 662         }
 663
 664         if (*hex != '\0')
 665                 return -EINVAL;
 666
 667         return 0;
 668 }
 669
 670 /*
 671  * Encode key into its hex representation
 672  */
 673 static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
 674 {
 675         unsigned int i;
 676
 677         for (i = 0; i < size; i++) {
 678                 sprintf(hex, "%02x", *key);
 679                 hex += 2;
 680                 key++;
 681         }
 682 }
 683
 684 static int crypt_set_key(struct crypt_config *cc, char *key)
 685 {
 686         unsigned key_size = strlen(key) >> 1;
 687
 688         if (cc->key_size && cc->key_size != key_size)
 689                 return -EINVAL;
 690
 691         cc->key_size = key_size; /* initial settings */
 692
 693         if ((!key_size && strcmp(key, "-")) ||
 694             (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
 695                 return -EINVAL;
 696
 697         set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 698
 699         return 0;
 700 }
 701
 702 static int crypt_wipe_key(struct crypt_config *cc)
 703 {
 704         clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 705         memset(&cc->key, 0, cc->key_size * sizeof(u8));
 706         return 0;
 707 }
 708
 709 /*
 710  * Construct an encryption mapping:
 711  * <cipher> <key> <iv_offset> <dev_path> <start>
 712  */
 713 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 714 {
 715         struct crypt_config *cc;
 716         struct crypto_blkcipher *tfm;
 717         char *tmp;
 718         char *cipher;
 719         char *chainmode;
 720         char *ivmode;
 721         char *ivopts;
 722         unsigned int key_size;
 723         unsigned long long tmpll;
 724
 725         if (argc != 5) {
 726                 ti->error = "Not enough arguments";
 727                 return -EINVAL;
 728         }
 729
 730         tmp = argv[0];
 731         cipher = strsep(&tmp, "-");
 732         chainmode = strsep(&tmp, "-");
 733         ivopts = strsep(&tmp, "-");
 734         ivmode = strsep(&ivopts, ":");
 735
 736         if (tmp)
 737                 DMWARN("Unexpected additional cipher options");
 738
 739         key_size = strlen(argv[1]) >> 1;
 740
 741         cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
 742         if (cc == NULL) {
 743                 ti->error =
 744                         "Cannot allocate transparent encryption context";
 745                 return -ENOMEM;
 746         }
 747
 748         if (crypt_set_key(cc, argv[1])) {
 749                 ti->error = "Error decoding key";
 750                 goto bad1;
 751         }
 752
 753         /* Compatiblity mode for old dm-crypt cipher strings */
 754         if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
 755                 chainmode = "cbc";
 756                 ivmode = "plain";
 757         }
 758
 759         if (strcmp(chainmode, "ecb") && !ivmode) {
 760                 ti->error = "This chaining mode requires an IV mechanism";
 761                 goto bad1;
 762         }
 763
 764         if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)", chainmode,
 765                      cipher) >= CRYPTO_MAX_ALG_NAME) {
 766                 ti->error = "Chain mode + cipher name is too long";
 767                 goto bad1;
 768         }
 769
 770         tfm = crypto_alloc_blkcipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 771         if (IS_ERR(tfm)) {
 772                 ti->error = "Error allocating crypto tfm";
 773                 goto bad1;
 774         }
 775
 776         strcpy(cc->cipher, cipher);
 777         strcpy(cc->chainmode, chainmode);
 778         cc->tfm = tfm;
 779
 780         /*
 781          * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
 782          * See comments at iv code
 783          */
 784
 785         if (ivmode == NULL)
 786                 cc->iv_gen_ops = NULL;
 787         else if (strcmp(ivmode, "plain") == 0)
 788                 cc->iv_gen_ops = &crypt_iv_plain_ops;
 789         else if (strcmp(ivmode, "essiv") == 0)
 790                 cc->iv_gen_ops = &crypt_iv_essiv_ops;
 791         else if (strcmp(ivmode, "benbi") == 0)
 792                 cc->iv_gen_ops = &crypt_iv_benbi_ops;
 793         else if (strcmp(ivmode, "null") == 0)
 794                 cc->iv_gen_ops = &crypt_iv_null_ops;
 795         else {
 796                 ti->error = "Invalid IV mode";
 797                 goto bad2;
 798         }
 799
 800         if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
 801             cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
 802                 goto bad2;
 803
 804         cc->iv_size = crypto_blkcipher_ivsize(tfm);
 805         if (cc->iv_size)
 806                 /* at least a 64 bit sector number should fit in our buffer */
 807                 cc->iv_size = max(cc->iv_size,
 808                                   (unsigned int)(sizeof(u64) / sizeof(u8)));
 809         else {
 810                 if (cc->iv_gen_ops) {
 811                         DMWARN("Selected cipher does not support IVs");
 812                         if (cc->iv_gen_ops->dtr)
 813                                 cc->iv_gen_ops->dtr(cc);
 814                         cc->iv_gen_ops = NULL;
 815                 }
 816         }
 817
 818         cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
 819         if (!cc->io_pool) {
 820                 ti->error = "Cannot allocate crypt io mempool";
 821                 goto bad3;
 822         }
 823
 824         cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
 825         if (!cc->page_pool) {
 826                 ti->error = "Cannot allocate page mempool";
 827                 goto bad4;
 828         }
 829
 830         cc->bs = bioset_create(MIN_IOS, MIN_IOS);
 831         if (!cc->bs) {
 832                 ti->error = "Cannot allocate crypt bioset";
 833                 goto bad_bs;
 834         }
 835
 836         if (crypto_blkcipher_setkey(tfm, cc->key, key_size) < 0) {
 837                 ti->error = "Error setting key";
 838                 goto bad5;
 839         }
 840
 841         if (sscanf(argv[2], "%llu", &tmpll) != 1) {
 842                 ti->error = "Invalid iv_offset sector";
 843                 goto bad5;
 844         }
 845         cc->iv_offset = tmpll;
 846
 847         if (sscanf(argv[4], "%llu", &tmpll) != 1) {
 848                 ti->error = "Invalid device sector";
 849                 goto bad5;
 850         }
 851         cc->start = tmpll;
 852
 853         if (dm_get_device(ti, argv[3], cc->start, ti->len,
 854                           dm_table_get_mode(ti->table), &cc->dev)) {
 855                 ti->error = "Device lookup failed";
 856                 goto bad5;
 857         }
 858
 859         if (ivmode && cc->iv_gen_ops) {
 860                 if (ivopts)
 861                         *(ivopts - 1) = ':';
 862                 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
 863                 if (!cc->iv_mode) {
 864                         ti->error = "Error kmallocing iv_mode string";
 865                         goto bad_iv_mode;
 866                 }
 867                 strcpy(cc->iv_mode, ivmode);
 868         } else
 869                 cc->iv_mode = NULL;
 870
 871         ti->private = cc;
 872         return 0;
 873
 874 bad_iv_mode:
 875         dm_put_device(ti, cc->dev);
 876 bad5:
 877         bioset_free(cc->bs);
 878 bad_bs:
 879         mempool_destroy(cc->page_pool);
 880 bad4:
 881         mempool_destroy(cc->io_pool);
 882 bad3:
 883         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 884                 cc->iv_gen_ops->dtr(cc);
 885 bad2:
 886         crypto_free_blkcipher(tfm);
 887 bad1:
 888         /* Must zero key material before freeing */
 889         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 890         kfree(cc);
 891         return -EINVAL;
 892 }
 893
 894 static void crypt_dtr(struct dm_target *ti)
 895 {
 896         struct crypt_config *cc = (struct crypt_config *) ti->private;
 897
 898         flush_workqueue(_kcryptd_workqueue);
 899
 900         bioset_free(cc->bs);
 901         mempool_destroy(cc->page_pool);
 902         mempool_destroy(cc->io_pool);
 903
 904         kfree(cc->iv_mode);
 905         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 906                 cc->iv_gen_ops->dtr(cc);
 907         crypto_free_blkcipher(cc->tfm);
 908         dm_put_device(ti, cc->dev);
 909
 910         /* Must zero key material before freeing */
 911         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 912         kfree(cc);
 913 }
 914
 915 static int crypt_map(struct dm_target *ti, struct bio *bio,
 916                      union map_info *map_context)
 917 {
 918         struct crypt_config *cc = ti->private;
 919         struct dm_crypt_io *io;
 920
 921         io = mempool_alloc(cc->io_pool, GFP_NOIO);
 922         io->target = ti;
 923         io->base_bio = bio;
 924         io->error = io->post_process = 0;
 925         atomic_set(&io->pending, 0);
 926         kcryptd_queue_io(io);
 927
 928         return DM_MAPIO_SUBMITTED;
 929 }
 930
 931 static int crypt_status(struct dm_target *ti, status_type_t type,
 932                         char *result, unsigned int maxlen)
 933 {
 934         struct crypt_config *cc = (struct crypt_config *) ti->private;
 935         unsigned int sz = 0;
 936
 937         switch (type) {
 938         case STATUSTYPE_INFO:
 939                 result[0] = '\0';
 940                 break;
 941
 942         case STATUSTYPE_TABLE:
 943                 if (cc->iv_mode)
 944                         DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
 945                                cc->iv_mode);
 946                 else
 947                         DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
 948
 949                 if (cc->key_size > 0) {
 950                         if ((maxlen - sz) < ((cc->key_size << 1) + 1))
 951                                 return -ENOMEM;
 952
 953                         crypt_encode_key(result + sz, cc->key, cc->key_size);
 954                         sz += cc->key_size << 1;
 955                 } else {
 956                         if (sz >= maxlen)
 957                                 return -ENOMEM;
 958                         result[sz++] = '-';
 959                 }
 960
 961                 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
 962                                 cc->dev->name, (unsigned long long)cc->start);
 963                 break;
 964         }
 965         return 0;
 966 }
 967
 968 static void crypt_postsuspend(struct dm_target *ti)
 969 {
 970         struct crypt_config *cc = ti->private;
 971
 972         set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
 973 }
 974
 975 static int crypt_preresume(struct dm_target *ti)
 976 {
 977         struct crypt_config *cc = ti->private;
 978
 979         if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
 980                 DMERR("aborting resume - crypt key is not set.");
 981                 return -EAGAIN;
 982         }
 983
 984         return 0;
 985 }
 986
 987 static void crypt_resume(struct dm_target *ti)
 988 {
 989         struct crypt_config *cc = ti->private;
 990
 991         clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
 992 }
 993
 994 /* Message interface
 995  *      key set <key>
 996  *      key wipe
 997  */
 998 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
 999 {
1000         struct crypt_config *cc = ti->private;
1001
1002         if (argc < 2)
1003                 goto error;
1004
1005         if (!strnicmp(argv[0], MESG_STR("key"))) {
1006                 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
1007                         DMWARN("not suspended during key manipulation.");
1008                         return -EINVAL;
1009                 }
1010                 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
1011                         return crypt_set_key(cc, argv[2]);
1012                 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
1013                         return crypt_wipe_key(cc);
1014         }
1015
1016 error:
1017         DMWARN("unrecognised message received.");
1018         return -EINVAL;
1019 }
1020
1021 static struct target_type crypt_target = {
1022         .name   = "crypt",
1023         .version= {1, 5, 0},
1024         .module = THIS_MODULE,
1025         .ctr    = crypt_ctr,
1026         .dtr    = crypt_dtr,
1027         .map    = crypt_map,
1028         .status = crypt_status,
1029         .postsuspend = crypt_postsuspend,
1030         .preresume = crypt_preresume,
1031         .resume = crypt_resume,
1032         .message = crypt_message,
1033 };
1034
1035 static int __init dm_crypt_init(void)
1036 {
1037         int r;
1038
1039         _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
1040         if (!_crypt_io_pool)
1041                 return -ENOMEM;
1042
1043         _kcryptd_workqueue = create_workqueue("kcryptd");
1044         if (!_kcryptd_workqueue) {
1045                 r = -ENOMEM;
1046                 DMERR("couldn't create kcryptd");
1047                 goto bad1;
1048         }
1049
1050         r = dm_register_target(&crypt_target);
1051         if (r < 0) {
1052                 DMERR("register failed %d", r);
1053                 goto bad2;
1054         }
1055
1056         return 0;
1057
1058 bad2:
1059         destroy_workqueue(_kcryptd_workqueue);
1060 bad1:
1061         kmem_cache_destroy(_crypt_io_pool);
1062         return r;
1063 }
1064
1065 static void __exit dm_crypt_exit(void)
1066 {
1067         int r = dm_unregister_target(&crypt_target);
1068
1069         if (r < 0)
1070                 DMERR("unregister failed %d", r);
1071
1072         destroy_workqueue(_kcryptd_workqueue);
1073         kmem_cache_destroy(_crypt_io_pool);
1074 }
1075
1076 module_init(dm_crypt_init);
1077 module_exit(dm_crypt_exit);
1078
1079 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
1080 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
1081 MODULE_LICENSE("GPL");