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Subject[PATCH 4.19 065/103] dm crypt: fix parsing of extended IV arguments
Date
4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Milan Broz <gmazyland@gmail.com>

commit 1856b9f7bcc8e9bdcccc360aabb56fbd4dd6c565 upstream.

The dm-crypt cipher specification in a mapping table is defined as:
cipher[:keycount]-chainmode-ivmode[:ivopts]
or (new crypt API format):
capi:cipher_api_spec-ivmode[:ivopts]

For ESSIV, the parameter includes hash specification, for example:
aes-cbc-essiv:sha256

The implementation expected that additional IV option to never include
another dash '-' character.

But, with SHA3, there are names like sha3-256; so the mapping table
parser fails:

dmsetup create test --table "0 8 crypt aes-cbc-essiv:sha3-256 9c1185a5c5e9fc54612808977ee8f5b9e 0 /dev/sdb 0"
or (new crypt API format)
dmsetup create test --table "0 8 crypt capi:cbc(aes)-essiv:sha3-256 9c1185a5c5e9fc54612808977ee8f5b9e 0 /dev/sdb 0"

device-mapper: crypt: Ignoring unexpected additional cipher options
device-mapper: table: 253:0: crypt: Error creating IV
device-mapper: ioctl: error adding target to table

Fix the dm-crypt constructor to ignore additional dash in IV options and
also remove a bogus warning (that is ignored anyway).

Cc: stable@vger.kernel.org # 4.12+
Signed-off-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/md/dm-crypt.c | 25 +++++++++++++++++--------
1 file changed, 17 insertions(+), 8 deletions(-)

--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2405,9 +2405,21 @@ static int crypt_ctr_cipher_new(struct d
* capi:cipher_api_spec-iv:ivopts
*/
tmp = &cipher_in[strlen("capi:")];
- cipher_api = strsep(&tmp, "-");
- *ivmode = strsep(&tmp, ":");
- *ivopts = tmp;
+
+ /* Separate IV options if present, it can contain another '-' in hash name */
+ *ivopts = strrchr(tmp, ':');
+ if (*ivopts) {
+ **ivopts = '\0';
+ (*ivopts)++;
+ }
+ /* Parse IV mode */
+ *ivmode = strrchr(tmp, '-');
+ if (*ivmode) {
+ **ivmode = '\0';
+ (*ivmode)++;
+ }
+ /* The rest is crypto API spec */
+ cipher_api = tmp;

if (*ivmode && !strcmp(*ivmode, "lmk"))
cc->tfms_count = 64;
@@ -2477,11 +2489,8 @@ static int crypt_ctr_cipher_old(struct d
goto bad_mem;

chainmode = strsep(&tmp, "-");
- *ivopts = strsep(&tmp, "-");
- *ivmode = strsep(&*ivopts, ":");
-
- if (tmp)
- DMWARN("Ignoring unexpected additional cipher options");
+ *ivmode = strsep(&tmp, ":");
+ *ivopts = tmp;

/*
* For compatibility with the original dm-crypt mapping format, if

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