[PATCH v9 6/7] luks2: Add detached header support

[Glenn Washburn]

If a header file is given to the LUKS2 backend, use that file as the LUKS2
header, instead of looking for it on the disk.

Signed-off-by: Glenn Washburn <development@efficientek.com>
---
 grub-core/disk/luks2.c | 67 ++++++++++++++++++++++++++++++------------
 1 file changed, 49 insertions(+), 18 deletions(-)

diff --git a/grub-core/disk/luks2.c b/grub-core/disk/luks2.c
index 349462c61a..af5bc4fc82 100644
--- a/grub-core/disk/luks2.c
+++ b/grub-core/disk/luks2.c
@@ -313,13 +313,22 @@ luks2_get_keyslot (grub_luks2_keyslot_t *k, 
grub_luks2_digest_t *d, grub_luks2_s
 
 /* Determine whether to use primary or secondary header */
 static grub_err_t
-luks2_read_header (grub_disk_t disk, grub_luks2_header_t *outhdr)
+luks2_read_header (grub_disk_t disk, grub_file_t hdr_file, grub_luks2_header_t 
*outhdr)
 {
   grub_luks2_header_t primary, secondary, *header = &primary;
-  grub_err_t ret;
+  grub_err_t ret = GRUB_ERR_NONE;
 
   /* Read the primary LUKS header. */
-  ret = grub_disk_read (disk, 0, 0, sizeof (primary), &primary);
+  if (hdr_file)
+    {
+      if (grub_file_seek (hdr_file, 0) == (grub_off_t) -1)
+       ret = grub_errno;
+
+      else if (grub_file_read (hdr_file, &primary, sizeof (primary)) != sizeof 
(primary))
+       ret = grub_errno;
+    }
+  else
+    ret = grub_disk_read (disk, 0, 0, sizeof (primary), &primary);
   if (ret)
     return ret;
 
@@ -329,7 +338,16 @@ luks2_read_header (grub_disk_t disk, grub_luks2_header_t 
*outhdr)
     return GRUB_ERR_BAD_SIGNATURE;
 
   /* Read the secondary header. */
-  ret = grub_disk_read (disk, 0, grub_be_to_cpu64 (primary.hdr_size), sizeof 
(secondary), &secondary);
+  if (hdr_file)
+    {
+      if (grub_file_seek (hdr_file, grub_be_to_cpu64 (primary.hdr_size)) == 
(grub_off_t) -1)
+       ret = grub_errno;
+
+      else if (grub_file_read (hdr_file, &secondary, sizeof (secondary)) != 
sizeof (secondary))
+       ret = grub_errno;
+    }
+  else
+    ret = grub_disk_read (disk, 0, grub_be_to_cpu64 (primary.hdr_size), sizeof 
(secondary), &secondary);
   if (ret)
     return ret;
 
@@ -353,14 +371,10 @@ luks2_scan (grub_disk_t disk, grub_cryptomount_args_t 
cargs)
   char uuid[sizeof (header.uuid) + 1];
   grub_size_t i, j;
 
-  /* Detached headers are not implemented yet */
-  if (cargs->hdr_file)
-    return NULL;
-
   if (cargs->check_boot)
     return NULL;
 
-  if (luks2_read_header (disk, &header))
+  if (luks2_read_header (disk, cargs->hdr_file, &header))
     {
       grub_errno = GRUB_ERR_NONE;
       return NULL;
@@ -427,6 +441,7 @@ luks2_verify_key (grub_luks2_digest_t *d, grub_uint8_t 
*candidate_key,
 static grub_err_t
 luks2_decrypt_key (grub_uint8_t *out_key,
                   grub_disk_t source, grub_cryptodisk_t crypt,
+                  grub_cryptomount_args_t cargs,
                   grub_luks2_keyslot_t *k,
                   const grub_uint8_t *passphrase, grub_size_t passphraselen)
 {
@@ -502,7 +517,17 @@ luks2_decrypt_key (grub_uint8_t *out_key,
     }
 
   grub_errno = GRUB_ERR_NONE;
-  ret = grub_disk_read (source, 0, k->area.offset, k->area.size, split_key);
+  if (cargs->hdr_file)
+    {
+      if (grub_file_seek (cargs->hdr_file, k->area.offset) == (grub_off_t) -1)
+       ret = grub_errno;
+
+      else if (grub_file_read (cargs->hdr_file, split_key, k->area.size) != 
k->area.size)
+       ret = grub_errno;
+    }
+  else
+    ret = grub_disk_read (source, 0, k->area.offset, k->area.size, split_key);
+
   if (ret)
     {
       grub_error (GRUB_ERR_IO, "Read error: %s\n", grub_errmsg);
@@ -564,11 +589,7 @@ luks2_recover_key (grub_disk_t source,
   if (cargs->key_data == NULL || cargs->key_len == 0)
     return grub_error (GRUB_ERR_BAD_ARGUMENT, "no key data");
 
-  /* Detached headers are not implemented yet */
-  if (cargs->hdr_file)
-     return GRUB_ERR_NOT_IMPLEMENTED_YET;
-
-  ret = luks2_read_header (source, &header);
+  ret = luks2_read_header (source, cargs->hdr_file, &header);
   if (ret)
     return ret;
 
@@ -577,8 +598,18 @@ luks2_recover_key (grub_disk_t source,
       return GRUB_ERR_OUT_OF_MEMORY;
 
   /* Read the JSON area. */
-  ret = grub_disk_read (source, 0, grub_be_to_cpu64 (header.hdr_offset) + 
sizeof (header),
-                       grub_be_to_cpu64 (header.hdr_size) - sizeof (header), 
json_header);
+  if (cargs->hdr_file)
+    {
+      if (grub_file_seek (cargs->hdr_file, grub_be_to_cpu64 
(header.hdr_offset) + sizeof (header)) == (grub_off_t) -1)
+       ret = grub_errno;
+
+      else if (grub_file_read (cargs->hdr_file, json_header, grub_be_to_cpu64 
(header.hdr_size) - sizeof (header)) != (grub_be_to_cpu64 (header.hdr_size) - 
sizeof (header)))
+       ret = grub_errno;
+    }
+  else
+    ret = grub_disk_read (source, 0, grub_be_to_cpu64 (header.hdr_offset) + 
sizeof (header),
+                         grub_be_to_cpu64 (header.hdr_size) - sizeof (header), 
json_header);
+
   if (ret)
       goto err;
 
@@ -716,7 +747,7 @@ luks2_recover_key (grub_disk_t source,
          crypt->total_sectors = max_crypt_sectors - crypt->offset_sectors;
        }
 
-      ret = luks2_decrypt_key (candidate_key, source, crypt, &keyslot,
+      ret = luks2_decrypt_key (candidate_key, source, crypt, cargs, &keyslot,
                               cargs->key_data, cargs->key_len);
       if (ret)
        {
-- 
2.25.1