From 48527fa7cf7fefb84e9fe03cddd08ddafc9f15f3 Mon Sep 17 00:00:00 2001 From: Rik Snel Date: Sun, 3 Sep 2006 08:56:39 +1000 Subject: [PATCH] [BLOCK] dm-crypt: benbi IV, big endian narrow block count for LRW-32-AES LRW-32-AES needs a certain IV. This IV should be provided dm-crypt. The block cipher mode could, in principle generate the correct IV from the plain IV, but I think that it is cleaner to supply the right IV directly. The sector -> narrow block calculation uses a shift for performance reasons. This shift is computed in .ctr and stored in cc->iv_gen_private (as a void *). Signed-off-by: Rik Snel Signed-off-by: Herbert Xu --- drivers/md/dm-crypt.c | 51 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 50 insertions(+), 1 deletion(-) diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index ed2d4ef27fd8..6dbaeee48ced 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -20,6 +20,7 @@ #include #include #include +#include #include "dm.h" @@ -113,6 +114,9 @@ static kmem_cache_t *_crypt_io_pool; * encrypted with the bulk cipher using a salt as key. The salt * should be derived from the bulk cipher's key via hashing. * + * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1 + * (needed for LRW-32-AES and possible other narrow block modes) + * * plumb: unimplemented, see: * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454 */ @@ -209,6 +213,44 @@ static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector) return 0; } +static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti, + const char *opts) +{ + unsigned int bs = crypto_blkcipher_blocksize(cc->tfm); + int log = long_log2(bs); + + /* we need to calculate how far we must shift the sector count + * to get the cipher block count, we use this shift in _gen */ + + if (1 << log != bs) { + ti->error = "cypher blocksize is not a power of 2"; + return -EINVAL; + } + + if (log > 9) { + ti->error = "cypher blocksize is > 512"; + return -EINVAL; + } + + cc->iv_gen_private = (void *)(9 - log); + + return 0; +} + +static void crypt_iv_benbi_dtr(struct crypt_config *cc) +{ + cc->iv_gen_private = NULL; +} + +static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector) +{ + memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */ + put_unaligned(cpu_to_be64(((u64)sector << (u32)cc->iv_gen_private) + 1), + (__be64 *)(iv + cc->iv_size - sizeof(u64))); + + return 0; +} + static struct crypt_iv_operations crypt_iv_plain_ops = { .generator = crypt_iv_plain_gen }; @@ -219,6 +261,11 @@ static struct crypt_iv_operations crypt_iv_essiv_ops = { .generator = crypt_iv_essiv_gen }; +static struct crypt_iv_operations crypt_iv_benbi_ops = { + .ctr = crypt_iv_benbi_ctr, + .dtr = crypt_iv_benbi_dtr, + .generator = crypt_iv_benbi_gen +}; static int crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out, @@ -768,7 +815,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) cc->tfm = tfm; /* - * Choose ivmode. Valid modes: "plain", "essiv:". + * Choose ivmode. Valid modes: "plain", "essiv:", "benbi". * See comments at iv code */ @@ -778,6 +825,8 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) cc->iv_gen_ops = &crypt_iv_plain_ops; else if (strcmp(ivmode, "essiv") == 0) cc->iv_gen_ops = &crypt_iv_essiv_ops; + else if (strcmp(ivmode, "benbi") == 0) + cc->iv_gen_ops = &crypt_iv_benbi_ops; else { ti->error = "Invalid IV mode"; goto bad2; -- 2.20.1