Milan Broz e853aa2e7c Fix blockwise access functions for systems with big page size. ...

Initially cryptsetup expected underlying device that was, by definition,
always aligned to a sector size (and length was always multiple of sectors).

For the images in file, we can now access the image directly.
Expecting that the image is always aligned to the whole block is now false
(the last block in file image can be incomplete).

Moreover, we cannot easily detect underlying block device sector (block) size
(the storage stack can be complex with various RAID and loop block sizes),
so code uses systyem PAGE_SIZE in this situation (should be the safest way).

Unfortunately, PAGE_SIZE can be bigger (1MB) than device sector (4k) and
the blockwise functions then fails because the image in file is not
aligned to PAGE_SIZE multiple..

Fix it by checking that read/write for the last part of an image is
the exact requested size and not a full block.

(The problem is for example for an unaligned hidden Truecrypt header
on PPC64LE systems, where page size is 64k.)

2017-07-24 14:17:21 +02:00

7.4 KiB

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