crypto: enforce that LUKS stripes is always a fixed value

Although the LUKS stripes are encoded in the keyslot header and so
potentially configurable, in pratice the cryptsetup impl mandates
this has the fixed value 4000. To avoid incompatibility apply the
same enforcement in QEMU too. This also caps the memory usage for
key material when QEMU tries to open a LUKS volume.

Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

diff --git a/crypto/block-luks.c b/crypto/block-luks.c
index 27d1b34c1d28ab2995a12973e28aa9e6f5240ea6..81744e2a8ee59cf13ba78ba241ca24cd3eac1cce 100644 (file)
--- a/crypto/block-luks.c
+++ b/crypto/block-luks.c
@@ -582,8 +582,9 @@ qcrypto_block_luks_check_header(const QCryptoBlockLUKS *luks, Error **errp)
                                                    header_sectors,
                                                    slot1->stripes);
 
-        if (slot1->stripes == 0) {
-            error_setg(errp, "Keyslot %zu is corrupted (stripes == 0)", i);
+        if (slot1->stripes != QCRYPTO_BLOCK_LUKS_STRIPES) {
+            error_setg(errp, "Keyslot %zu is corrupted (stripes %d != %d)",
+                       i, slot1->stripes, QCRYPTO_BLOCK_LUKS_STRIPES);
             return -1;
         }