[PATCH v2 4/9] luks2: grub_cryptodisk_t->total_length is the max number of device native sectors

[Patrick Steinhardt]

From: Glenn Washburn <development@efficientek.com>

The total_length field is named confusingly because length usually refers to
bytes, whereas in this case its really the total number of sectors on the
device. Also counter-intuitively, grub_disk_get_size returns the total
number of device native sectors sectors. We need to convert the sectors from
the size of the underlying device to the cryptodisk sector size. And
segment.size is in bytes which need to be converted to cryptodisk sectors.

Signed-off-by: Glenn Washburn <development@efficientek.com>
---
 grub-core/disk/luks2.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/grub-core/disk/luks2.c b/grub-core/disk/luks2.c
index c4c6ac90c..5f15a4d2c 100644
--- a/grub-core/disk/luks2.c
+++ b/grub-core/disk/luks2.c
@@ -417,7 +417,7 @@ luks2_decrypt_key (grub_uint8_t *out_key,
   grub_uint8_t salt[GRUB_CRYPTODISK_MAX_KEYLEN];
   grub_uint8_t *split_key = NULL;
   grub_size_t saltlen = sizeof (salt);
-  char cipher[32], *p;;
+  char cipher[32], *p;
   const gcry_md_spec_t *hash;
   gcry_err_code_t gcry_ret;
   grub_err_t ret;
@@ -603,9 +603,10 @@ luks2_recover_key (grub_disk_t disk,
       crypt->log_sector_size = sizeof (unsigned int) * 8
                - __builtin_clz ((unsigned int) segment.sector_size) - 1;
       if (grub_strcmp (segment.size, "dynamic") == 0)
-       crypt->total_length = grub_disk_get_size (disk) - crypt->offset;
+       crypt->total_length = (grub_disk_get_size (disk) >> 
(crypt->log_sector_size - disk->log_sector_size))
+                              - crypt->offset;
       else
-       crypt->total_length = grub_strtoull (segment.size, NULL, 10);
+       crypt->total_length = grub_strtoull (segment.size, NULL, 10) >> 
crypt->log_sector_size;
 
       ret = luks2_decrypt_key (candidate_key, disk, crypt, &keyslot,
                               (const grub_uint8_t *) passphrase, grub_strlen 
(passphrase));
-- 
2.28.0

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