dm crypt: fix parsing of extended IV arguments

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>

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 0ff2215..47d4e0d 100644 (file)
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2414,9 +2414,21 @@ static int crypt_ctr_cipher_new(struct dm_target *ti, char *cipher_in, char *key
         * 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;
@@ -2486,11 +2498,8 @@ static int crypt_ctr_cipher_old(struct dm_target *ti, char *cipher_in, char *key
                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