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From 5d29bc014a33d9bdc1c5fb4b8add2f38850f46a8 Mon Sep 17 00:00:00 2001
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From: Vojtech Trefny <vtrefny@redhat.com>
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Date: Wed, 24 Feb 2021 14:44:03 +0100
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Subject: [PATCH] crypto: Fix default key size for non XTS ciphers
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512 bits should be default only for AES-XTS which needs two keys,
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default for other modes must be 256 bits.
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resolves: rhbz#1931847
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---
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src/plugins/crypto.c | 11 +++++++++--
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src/plugins/crypto.h | 2 +-
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tests/crypto_test.py | 36 ++++++++++++++++++++++++++++++++++++
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3 files changed, 46 insertions(+), 3 deletions(-)
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diff --git a/src/plugins/crypto.c b/src/plugins/crypto.c
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index f4a2e8f0..1e7043fa 100644
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--- a/src/plugins/crypto.c
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+++ b/src/plugins/crypto.c
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@@ -774,8 +774,15 @@ static gboolean luks_format (const gchar *device, const gchar *cipher, guint64 k
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return FALSE;
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}
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- /* resolve requested/default key_size (should be in bytes) */
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- key_size = (key_size != 0) ? (key_size / 8) : (DEFAULT_LUKS_KEYSIZE_BITS / 8);
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+ if (key_size == 0) {
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+ if (g_str_has_prefix (cipher_specs[1], "xts-"))
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+ key_size = DEFAULT_LUKS_KEYSIZE_BITS * 2;
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+ else
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+ key_size = DEFAULT_LUKS_KEYSIZE_BITS;
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+ }
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+
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+ /* key_size should be in bytes */
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+ key_size = key_size / 8;
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/* wait for enough random data entropy (if requested) */
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if (min_entropy > 0) {
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diff --git a/src/plugins/crypto.h b/src/plugins/crypto.h
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index 71a1438d..a38724d9 100644
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--- a/src/plugins/crypto.h
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+++ b/src/plugins/crypto.h
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@@ -36,7 +36,7 @@ typedef enum {
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/* 20 chars * 6 bits per char (64-item charset) = 120 "bits of security" */
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#define BD_CRYPTO_BACKUP_PASSPHRASE_LENGTH 20
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-#define DEFAULT_LUKS_KEYSIZE_BITS 512
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+#define DEFAULT_LUKS_KEYSIZE_BITS 256
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#define DEFAULT_LUKS_CIPHER "aes-xts-plain64"
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#define DEFAULT_LUKS2_SECTOR_SIZE 512
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diff --git a/tests/crypto_test.py b/tests/crypto_test.py
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index 0609a070..0aecc032 100644
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--- a/tests/crypto_test.py
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+++ b/tests/crypto_test.py
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@@ -236,6 +236,42 @@ def test_luks2_format(self):
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self.fail("Failed to get pbkdf information from:\n%s %s" % (out, err))
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self.assertEqual(int(m.group(1)), 5)
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+ def _get_luks1_key_size(self, device):
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+ _ret, out, err = run_command("cryptsetup luksDump %s" % device)
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+ m = re.search(r"MK bits:\s*(\S+)\s*", out)
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+ if not m or len(m.groups()) != 1:
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+ self.fail("Failed to get key size information from:\n%s %s" % (out, err))
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+ key_size = m.group(1)
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+ if not key_size.isnumeric():
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+ self.fail("Failed to get key size information from: %s" % key_size)
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+ return int(key_size)
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+
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+ @tag_test(TestTags.SLOW, TestTags.CORE)
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+ def test_luks_format_key_size(self):
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+ """Verify that formating device as LUKS works"""
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+
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+ # aes-xts: key size should default to 512
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+ succ = BlockDev.crypto_luks_format(self.loop_dev, "aes-xts-plain64", 0, PASSWD, None, 0)
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+ self.assertTrue(succ)
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+
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+ key_size = self._get_luks1_key_size(self.loop_dev)
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+ self.assertEqual(key_size, 512)
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+
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+ # aes-cbc: key size should default to 256
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+ succ = BlockDev.crypto_luks_format(self.loop_dev, "aes-cbc-essiv:sha256", 0, PASSWD, None, 0)
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+ self.assertTrue(succ)
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+
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+ key_size = self._get_luks1_key_size(self.loop_dev)
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+ self.assertEqual(key_size, 256)
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+
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+ # try specifying key size for aes-xts
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+ succ = BlockDev.crypto_luks_format(self.loop_dev, "aes-xts-plain64", 256, PASSWD, None, 0)
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+ self.assertTrue(succ)
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+
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+ key_size = self._get_luks1_key_size(self.loop_dev)
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+ self.assertEqual(key_size, 256)
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+
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+
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class CryptoTestResize(CryptoTestCase):
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def _get_key_location(self, device):
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