On Wed, Jul 29, 2020 at 04:50:11PM -0500, developm...@efficientek.com wrote: > From: Glenn Washburn <developm...@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 <developm...@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 e3ff7c83d..632309e3c 100644 > --- a/grub-core/disk/luks2.c > +++ b/grub-core/disk/luks2.c > @@ -416,7 +416,7 @@ 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; > @@ -602,9 +602,10 @@ 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;
Oops, thanks for catching this. Could you maybe add a comment wrt to the magic going on with `(crypt->log_sector_size - disk->log_sector_size)`? I didn't think too hard about it and am in a hurry, but the conversion isn't that obvious to me. > 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)); > -- > 2.25.1 >
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