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-rw-r--r--drivers/md/dm-crypt.c185
1 files changed, 183 insertions, 2 deletions
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index e0c61a326550..50ea7ed24dce 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2,6 +2,7 @@
* Copyright (C) 2003 Christophe Saout <christophe@saout.de>
* Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
* Copyright (C) 2006-2009 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2013 Milan Broz <gmazyland@gmail.com>
*
* This file is released under the GPL.
*/
@@ -98,6 +99,13 @@ struct iv_lmk_private {
u8 *seed;
};
+#define TCW_WHITENING_SIZE 16
+struct iv_tcw_private {
+ struct crypto_shash *crc32_tfm;
+ u8 *iv_seed;
+ u8 *whitening;
+};
+
/*
* Crypt: maps a linear range of a block device
* and encrypts / decrypts at the same time.
@@ -139,6 +147,7 @@ struct crypt_config {
struct iv_essiv_private essiv;
struct iv_benbi_private benbi;
struct iv_lmk_private lmk;
+ struct iv_tcw_private tcw;
} iv_gen_private;
sector_t iv_offset;
unsigned int iv_size;
@@ -231,6 +240,16 @@ static struct crypto_ablkcipher *any_tfm(struct crypt_config *cc)
* version 3: the same as version 2 with additional IV seed
* (it uses 65 keys, last key is used as IV seed)
*
+ * tcw: Compatible implementation of the block chaining mode used
+ * by the TrueCrypt device encryption system (prior to version 4.1).
+ * For more info see: http://www.truecrypt.org
+ * It operates on full 512 byte sectors and uses CBC
+ * with an IV derived from initial key and the sector number.
+ * In addition, whitening value is applied on every sector, whitening
+ * is calculated from initial key, sector number and mixed using CRC32.
+ * Note that this encryption scheme is vulnerable to watermarking attacks
+ * and should be used for old compatible containers access only.
+ *
* plumb: unimplemented, see:
* http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
*/
@@ -609,6 +628,153 @@ static int crypt_iv_lmk_post(struct crypt_config *cc, u8 *iv,
return r;
}
+static void crypt_iv_tcw_dtr(struct crypt_config *cc)
+{
+ struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
+
+ kzfree(tcw->iv_seed);
+ tcw->iv_seed = NULL;
+ kzfree(tcw->whitening);
+ tcw->whitening = NULL;
+
+ if (tcw->crc32_tfm && !IS_ERR(tcw->crc32_tfm))
+ crypto_free_shash(tcw->crc32_tfm);
+ tcw->crc32_tfm = NULL;
+}
+
+static int crypt_iv_tcw_ctr(struct crypt_config *cc, struct dm_target *ti,
+ const char *opts)
+{
+ struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
+
+ if (cc->key_size <= (cc->iv_size + TCW_WHITENING_SIZE)) {
+ ti->error = "Wrong key size for TCW";
+ return -EINVAL;
+ }
+
+ tcw->crc32_tfm = crypto_alloc_shash("crc32", 0, 0);
+ if (IS_ERR(tcw->crc32_tfm)) {
+ ti->error = "Error initializing CRC32 in TCW";
+ return PTR_ERR(tcw->crc32_tfm);
+ }
+
+ tcw->iv_seed = kzalloc(cc->iv_size, GFP_KERNEL);
+ tcw->whitening = kzalloc(TCW_WHITENING_SIZE, GFP_KERNEL);
+ if (!tcw->iv_seed || !tcw->whitening) {
+ crypt_iv_tcw_dtr(cc);
+ ti->error = "Error allocating seed storage in TCW";
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static int crypt_iv_tcw_init(struct crypt_config *cc)
+{
+ struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
+ int key_offset = cc->key_size - cc->iv_size - TCW_WHITENING_SIZE;
+
+ memcpy(tcw->iv_seed, &cc->key[key_offset], cc->iv_size);
+ memcpy(tcw->whitening, &cc->key[key_offset + cc->iv_size],
+ TCW_WHITENING_SIZE);
+
+ return 0;
+}
+
+static int crypt_iv_tcw_wipe(struct crypt_config *cc)
+{
+ struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
+
+ memset(tcw->iv_seed, 0, cc->iv_size);
+ memset(tcw->whitening, 0, TCW_WHITENING_SIZE);
+
+ return 0;
+}
+
+static int crypt_iv_tcw_whitening(struct crypt_config *cc,
+ struct dm_crypt_request *dmreq,
+ u8 *data)
+{
+ struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
+ u64 sector = cpu_to_le64((u64)dmreq->iv_sector);
+ u8 buf[TCW_WHITENING_SIZE];
+ struct {
+ struct shash_desc desc;
+ char ctx[crypto_shash_descsize(tcw->crc32_tfm)];
+ } sdesc;
+ int i, r;
+
+ /* xor whitening with sector number */
+ memcpy(buf, tcw->whitening, TCW_WHITENING_SIZE);
+ crypto_xor(buf, (u8 *)&sector, 8);
+ crypto_xor(&buf[8], (u8 *)&sector, 8);
+
+ /* calculate crc32 for every 32bit part and xor it */
+ sdesc.desc.tfm = tcw->crc32_tfm;
+ sdesc.desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+ for (i = 0; i < 4; i++) {
+ r = crypto_shash_init(&sdesc.desc);
+ if (r)
+ goto out;
+ r = crypto_shash_update(&sdesc.desc, &buf[i * 4], 4);
+ if (r)
+ goto out;
+ r = crypto_shash_final(&sdesc.desc, &buf[i * 4]);
+ if (r)
+ goto out;
+ }
+ crypto_xor(&buf[0], &buf[12], 4);
+ crypto_xor(&buf[4], &buf[8], 4);
+
+ /* apply whitening (8 bytes) to whole sector */
+ for (i = 0; i < ((1 << SECTOR_SHIFT) / 8); i++)
+ crypto_xor(data + i * 8, buf, 8);
+out:
+ memset(buf, 0, sizeof(buf));
+ return r;
+}
+
+static int crypt_iv_tcw_gen(struct crypt_config *cc, u8 *iv,
+ struct dm_crypt_request *dmreq)
+{
+ struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
+ u64 sector = cpu_to_le64((u64)dmreq->iv_sector);
+ u8 *src;
+ int r = 0;
+
+ /* Remove whitening from ciphertext */
+ if (bio_data_dir(dmreq->ctx->bio_in) != WRITE) {
+ src = kmap_atomic(sg_page(&dmreq->sg_in));
+ r = crypt_iv_tcw_whitening(cc, dmreq, src + dmreq->sg_in.offset);
+ kunmap_atomic(src);
+ }
+
+ /* Calculate IV */
+ memcpy(iv, tcw->iv_seed, cc->iv_size);
+ crypto_xor(iv, (u8 *)&sector, 8);
+ if (cc->iv_size > 8)
+ crypto_xor(&iv[8], (u8 *)&sector, cc->iv_size - 8);
+
+ return r;
+}
+
+static int crypt_iv_tcw_post(struct crypt_config *cc, u8 *iv,
+ struct dm_crypt_request *dmreq)
+{
+ u8 *dst;
+ int r;
+
+ if (bio_data_dir(dmreq->ctx->bio_in) != WRITE)
+ return 0;
+
+ /* Apply whitening on ciphertext */
+ dst = kmap_atomic(sg_page(&dmreq->sg_out));
+ r = crypt_iv_tcw_whitening(cc, dmreq, dst + dmreq->sg_out.offset);
+ kunmap_atomic(dst);
+
+ return r;
+}
+
static struct crypt_iv_operations crypt_iv_plain_ops = {
.generator = crypt_iv_plain_gen
};
@@ -644,6 +810,15 @@ static struct crypt_iv_operations crypt_iv_lmk_ops = {
.post = crypt_iv_lmk_post
};
+static struct crypt_iv_operations crypt_iv_tcw_ops = {
+ .ctr = crypt_iv_tcw_ctr,
+ .dtr = crypt_iv_tcw_dtr,
+ .init = crypt_iv_tcw_init,
+ .wipe = crypt_iv_tcw_wipe,
+ .generator = crypt_iv_tcw_gen,
+ .post = crypt_iv_tcw_post
+};
+
static void crypt_convert_init(struct crypt_config *cc,
struct convert_context *ctx,
struct bio *bio_out, struct bio *bio_in,
@@ -1491,14 +1666,20 @@ static int crypt_ctr_cipher(struct dm_target *ti,
cc->iv_gen_ops = &crypt_iv_null_ops;
else if (strcmp(ivmode, "lmk") == 0) {
cc->iv_gen_ops = &crypt_iv_lmk_ops;
- /* Version 2 and 3 is recognised according
+ /*
+ * Version 2 and 3 is recognised according
* to length of provided multi-key string.
* If present (version 3), last key is used as IV seed.
+ * All keys (including IV seed) are always the same size.
*/
if (cc->key_size % cc->key_parts) {
cc->key_parts++;
cc->key_extra_size = cc->key_size / cc->key_parts;
}
+ } else if (strcmp(ivmode, "tcw") == 0) {
+ cc->iv_gen_ops = &crypt_iv_tcw_ops;
+ cc->key_parts += 2; /* IV + whitening */
+ cc->key_extra_size = cc->iv_size + TCW_WHITENING_SIZE;
} else {
ret = -EINVAL;
ti->error = "Invalid IV mode";
@@ -1824,7 +2005,7 @@ static int crypt_iterate_devices(struct dm_target *ti,
static struct target_type crypt_target = {
.name = "crypt",
- .version = {1, 12, 1},
+ .version = {1, 13, 0},
.module = THIS_MODULE,
.ctr = crypt_ctr,
.dtr = crypt_dtr,
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-29 19:04:27 +0100