[PATCH v4 14/15] luks2: Better error handling when setting up the cryptodisk.

[Glenn Washburn]

Signed-off-by: Glenn Washburn <development@efficientek.com>
---
 grub-core/disk/luks2.c | 70 +++++++++++++++++++++++++++++++++++++++---
 include/grub/misc.h    |  2 ++
 2 files changed, 67 insertions(+), 5 deletions(-)

diff --git a/grub-core/disk/luks2.c b/grub-core/disk/luks2.c
index 4a4a0dec4..751b48d6a 100644
--- a/grub-core/disk/luks2.c
+++ b/grub-core/disk/luks2.c
@@ -600,9 +600,16 @@ luks2_recover_key (grub_disk_t source,
       goto err;
     }
 
+  if (source->total_sectors == GRUB_DISK_SIZE_UNKNOWN)
+    {
+      ret = grub_error (GRUB_ERR_BUG, "not a luks2 device");
+      goto err;
+    }
+
   /* Try all keyslot */
   for (i = 0; i < size; i++)
     {
+      grub_errno = GRUB_ERR_NONE;
       ret = luks2_get_keyslot (&keyslot, &digest, &segment, json, i);
       if (ret)
        goto err;
@@ -617,13 +624,66 @@ luks2_recover_key (grub_disk_t source,
 
       /* Set up disk according to keyslot's segment. */
       crypt->offset_sectors = grub_divmod64 (segment.offset, 
segment.sector_size, NULL);
-      crypt->log_sector_size = sizeof (unsigned int) * 8
-               - __builtin_clz ((unsigned int) segment.sector_size) - 1;
+      crypt->log_sector_size = grub_log2ull (segment.sector_size);
       if (grub_strcmp (segment.size, "dynamic") == 0)
-       crypt->total_sectors = (grub_disk_get_size (source) >> 
(crypt->log_sector_size - source->log_sector_size))
-                              - crypt->offset_sectors;
+       {
+         /* Convert source sized number of sectors to cryptodisk sized sectors 
*/
+         crypt->total_sectors = source->total_sectors >> 
(crypt->log_sector_size - source->log_sector_size);
+         if (crypt->total_sectors < crypt->offset_sectors)
+           {
+             grub_dprintf ("luks2", "Segment \"%"PRIuGRUB_UINT64_T"\" offset"
+                                    " is greater than disk size.",
+                                     segment.slot_key);
+             continue;
+           }
+
+         crypt->total_sectors -= crypt->offset_sectors;
+       }
       else
-       crypt->total_sectors = grub_strtoull (segment.size, NULL, 10) >> 
crypt->log_sector_size;
+       {
+         crypt->total_sectors = grub_strtoull (segment.size, NULL, 10) >> 
crypt->log_sector_size;
+         if (grub_errno == GRUB_ERR_NONE)
+           ;
+         else if(grub_errno == GRUB_ERR_BAD_NUMBER)
+           {
+             /* TODO: Unparsable number-string, try to use the whole disk */
+             grub_dprintf ("luks2", "Segment \"%"PRIuGRUB_UINT64_T"\" size"
+                                    " is not a parsable number.",
+                                    segment.slot_key);
+             continue;
+           }
+         else if(grub_errno == GRUB_ERR_OUT_OF_RANGE)
+           {
+             /* There was an overflow in parsing segment.size, so disk must
+              * be very large or the string is incorrect. */
+             if ((source->total_sectors
+                   >> (crypt->log_sector_size - source->log_sector_size))
+                 > crypt->total_sectors)
+               {
+                 grub_dprintf ("luks2", "Segment \"%"PRIuGRUB_UINT64_T"\""
+                                        " size is very large. The end may be"
+                                        " inaccessible.",
+                                        segment.slot_key);
+               }
+             else
+               {
+                 /* FIXME: Set total_sectors as in "dynamic" case. */
+                 grub_dprintf ("luks2", "Segment \"%"PRIuGRUB_UINT64_T"\""
+                                        " size greater than the source"
+                                        " device.",
+                                        segment.slot_key);
+                 continue;
+               }
+           }
+       }
+
+      if (crypt->total_sectors == 0)
+       {
+         grub_dprintf ("luks2", "Segment \"%"PRIuGRUB_UINT64_T"\" has"
+                                " zero sectors, skipping.",
+                                segment.slot_key);
+         continue;
+       }
 
       ret = luks2_decrypt_key (candidate_key, source, crypt, &keyslot,
                               (const grub_uint8_t *) passphrase, grub_strlen 
(passphrase));
diff --git a/include/grub/misc.h b/include/grub/misc.h
index b7ca6dd58..ec25131ba 100644
--- a/include/grub/misc.h
+++ b/include/grub/misc.h
@@ -481,5 +481,7 @@ void EXPORT_FUNC(grub_real_boot_time) (const char *file,
 
 #define grub_max(a, b) (((a) > (b)) ? (a) : (b))
 #define grub_min(a, b) (((a) < (b)) ? (a) : (b))
+#define grub_log2ull(n) (GRUB_TYPE_BITS (grub_uint64_t) \
+                         - __builtin_clzll (n) - 1)
 
 #endif /* ! GRUB_MISC_HEADER */
-- 
2.27.0