[dm-devel] [PATCH 1/3] dm crypt: wipe keys string immediately after key is set

[Milan Broz]

If the tfm key was set up correctly, do not keep another
copy of key and immediately replace it with zero string.

Signed-off-by: Milan Broz <mbroz at redhat.com>
---
 drivers/md/dm-crypt.c |   16 +++++++++++-----
 1 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 4e054bd..d748433 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1331,20 +1331,26 @@ static int crypt_setkey_allcpus(struct crypt_config *cc)
 
 static int crypt_set_key(struct crypt_config *cc, char *key)
 {
+	int r = -EINVAL, key_string_len = strlen(key);
+
 	/* The key size may not be changed. */
-	if (cc->key_size != (strlen(key) >> 1))
-		return -EINVAL;
+	if (cc->key_size != (key_string_len >> 1))
+		goto out;
 
 	/* Hyphen (which gives a key_size of zero) means there is no key. */
 	if (!cc->key_size && strcmp(key, "-"))
-		return -EINVAL;
+		goto out;
 
 	if (cc->key_size && crypt_decode_key(cc->key, key, cc->key_size) < 0)
-		return -EINVAL;
+		goto out;
 
 	set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 
-	return crypt_setkey_allcpus(cc);
+	r = crypt_setkey_allcpus(cc);
+out:
+	/* Wipe hexa key string as soon as possible */
+	memset(key, '0', key_string_len);
+	return r;
 }
 
 static int crypt_wipe_key(struct crypt_config *cc)
-- 
1.7.2.3