dm crypt: make wipe message also wipe tfm key

The "wipe key" message is used to wipe a volume key from memory
temporarily, for example when suspending to RAM.

There are two instances of the key in memory (inside crypto tfm)
but only one got wiped.  This patch wipes them both.

Cc: stable@kernel.org
Signed-off-by: NMilan Broz <mbroz@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

drivers/md/dm-crypt.c

@@ -934,14 +934,14 @@ static int crypt_set_key(struct crypt_config *cc, char *key)
 
 	set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 
-	return 0;
+	return crypto_ablkcipher_setkey(cc->tfm, cc->key, cc->key_size);
 }
 
 static int crypt_wipe_key(struct crypt_config *cc)
 {
 	clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 	memset(&cc->key, 0, cc->key_size * sizeof(u8));
-	return 0;
+	return crypto_ablkcipher_setkey(cc->tfm, cc->key, cc->key_size);
 }
 
 /*
@@ -983,11 +983,6 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		return -ENOMEM;
 	}
 
- 	if (crypt_set_key(cc, argv[1])) {
-		ti->error = "Error decoding key";
-		goto bad_cipher;
-	}
-
 	/* Compatibility mode for old dm-crypt cipher strings */
 	if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
 		chainmode = "cbc";
@@ -1015,6 +1010,11 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	strcpy(cc->chainmode, chainmode);
 	cc->tfm = tfm;
 
+	if (crypt_set_key(cc, argv[1]) < 0) {
+		ti->error = "Error decoding and setting key";
+		goto bad_ivmode;
+	}
+
 	/*
 	 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
 	 * See comments at iv code
@@ -1085,11 +1085,6 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		goto bad_bs;
 	}
 
-	if (crypto_ablkcipher_setkey(tfm, cc->key, key_size) < 0) {
-		ti->error = "Error setting key";
-		goto bad_device;
-	}
-
 	if (sscanf(argv[2], "%llu", &tmpll) != 1) {
 		ti->error = "Invalid iv_offset sector";
 		goto bad_device;