From dc94902bde1e158cd19c4deab208e5d6eb382a44 Mon Sep 17 00:00:00 2001
From: Ondrej Kozina <okozina@redhat.com>
Date: Fri, 12 Jan 2018 16:30:32 +0100
Subject: [PATCH] dm crypt: wipe kernel key copy after IV initialization
Git-commit: dc94902bde1e158cd19c4deab208e5d6eb382a44
Patch-mainline: v4.15-rc9
References: bsc#1093023

Loading key via kernel keyring service erases the internal
key copy immediately after we pass it in crypto layer. This is
wrong because IV is initialized later and we use wrong key
for the initialization (instead of real key there's just zeroed
block).

The bug may cause data corruption if key is loaded via kernel keyring
service first and later same crypt device is reactivated using exactly
same key in hexbyte representation, or vice versa. The bug (and fix)
affects only ciphers using following IVs: essiv, lmk and tcw.

Fixes: c538f6ec9f56 ("dm crypt: add ability to use keys from the kernel key retention service")
Cc: stable@vger.kernel.org # 4.10+
Signed-off-by: Ondrej Kozina <okozina@redhat.com>
Reviewed-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Coly Li <colyli@suse.de>

---
 drivers/md/dm-crypt.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 4cc3809b2a3a..971241409c30 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2058,9 +2058,6 @@ static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string
 
 	ret = crypt_setkey(cc);
 
-	/* wipe the kernel key payload copy in each case */
-	memset(cc->key, 0, cc->key_size * sizeof(u8));
-
 	if (!ret) {
 		set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 		kzfree(cc->key_string);
@@ -2528,6 +2525,10 @@ static int crypt_ctr_cipher(struct dm_target *ti, char *cipher_in, char *key)
 		}
 	}
 
+	/* wipe the kernel key payload copy */
+	if (cc->key_string)
+		memset(cc->key, 0, cc->key_size * sizeof(u8));
+
 	return ret;
 }
 
@@ -2966,6 +2967,9 @@ static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
 				return ret;
 			if (cc->iv_gen_ops && cc->iv_gen_ops->init)
 				ret = cc->iv_gen_ops->init(cc);
+			/* wipe the kernel key payload copy */
+			if (cc->key_string)
+				memset(cc->key, 0, cc->key_size * sizeof(u8));
 			return ret;
 		}
 		if (argc == 2 && !strcasecmp(argv[1], "wipe")) {
@@ -3012,7 +3016,7 @@ static void crypt_io_hints(struct dm_target *ti, struct queue_limits *limits)
 
 static struct target_type crypt_target = {
 	.name   = "crypt",
-	.version = {1, 18, 0},
+	.version = {1, 18, 1},
 	.module = THIS_MODULE,
 	.ctr    = crypt_ctr,
 	.dtr    = crypt_dtr,
-- 
2.16.3