[PATCH] cmd_set_passphrase: initialize KDF parameters

[Mae Kasza <git@badat.dev>]

From: mae <git@badat.dev>

The set-passphrase command failed to derive the key for disks initially
formatted with --encrypted and --no_passphrase.

This happened because bch_sb_crypt_init only configures the KDF params
if a passphrase is specified.
This commit makes the command initialize the KDF with the same parameters
as bch_sb_crypt_init if the key wasn't encrypted before.

Signed-off-by: Mae Kasza <git@badat.dev>
---
 c_src/cmd_key.c |  9 +++++++--
 c_src/crypto.c  | 13 ++++++++-----
 c_src/crypto.h  |  1 +
 3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/c_src/cmd_key.c b/c_src/cmd_key.c
index adb0ac8d..2da83758 100644
--- a/c_src/cmd_key.c
+++ b/c_src/cmd_key.c
@@ -104,7 +104,8 @@ int cmd_set_passphrase(int argc, char *argv[])
 	if (IS_ERR(c))
 		die("Error opening %s: %s", argv[1], bch2_err_str(PTR_ERR(c)));
 
-	struct bch_sb_field_crypt *crypt = bch2_sb_field_get(c->disk_sb.sb, crypt);
+	struct bch_sb *sb = c->disk_sb.sb;
+	struct bch_sb_field_crypt *crypt = bch2_sb_field_get(sb, crypt);
 	if (!crypt)
 		die("Filesystem does not have encryption enabled");
 
@@ -116,9 +117,13 @@ int cmd_set_passphrase(int argc, char *argv[])
 		die("Error getting current key");
 
 	char *new_passphrase = read_passphrase_twice("Enter new passphrase: ");
+	if (!bch2_key_is_encrypted(&crypt->key)) {
+		bch_crypt_default_kdf_init(crypt);
+	}
+
 	struct bch_key passphrase_key = derive_passphrase(crypt, new_passphrase);
 
-	if (bch2_chacha_encrypt_key(&passphrase_key, __bch2_sb_key_nonce(c->disk_sb.sb),
+	if (bch2_chacha_encrypt_key(&passphrase_key, __bch2_sb_key_nonce(sb),
 				    &new_key, sizeof(new_key)))
 		die("error encrypting key");
 	crypt->key = new_key;
diff --git a/c_src/crypto.c b/c_src/crypto.c
index 32671bd8..30ad92d4 100644
--- a/c_src/crypto.c
+++ b/c_src/crypto.c
@@ -180,11 +180,7 @@ void bch_sb_crypt_init(struct bch_sb *sb,
 	get_random_bytes(&crypt->key.key, sizeof(crypt->key.key));
 
 	if (passphrase) {
-
-		SET_BCH_CRYPT_KDF_TYPE(crypt, BCH_KDF_SCRYPT);
-		SET_BCH_KDF_SCRYPT_N(crypt, ilog2(16384));
-		SET_BCH_KDF_SCRYPT_R(crypt, ilog2(8));
-		SET_BCH_KDF_SCRYPT_P(crypt, ilog2(16));
+		bch_crypt_default_kdf_init(crypt);
 
 		struct bch_key passphrase_key = derive_passphrase(crypt, passphrase);
 
@@ -199,3 +195,10 @@ void bch_sb_crypt_init(struct bch_sb *sb,
 		memzero_explicit(&passphrase_key, sizeof(passphrase_key));
 	}
 }
+
+void bch_crypt_default_kdf_init(struct bch_sb_field_crypt *crypt) {
+		SET_BCH_CRYPT_KDF_TYPE(crypt, BCH_KDF_SCRYPT);
+		SET_BCH_KDF_SCRYPT_N(crypt, ilog2(16384));
+		SET_BCH_KDF_SCRYPT_R(crypt, ilog2(8));
+		SET_BCH_KDF_SCRYPT_P(crypt, ilog2(16));
+}
diff --git a/c_src/crypto.h b/c_src/crypto.h
index baea6d86..846a8931 100644
--- a/c_src/crypto.h
+++ b/c_src/crypto.h
@@ -18,5 +18,6 @@ void bch2_passphrase_check(struct bch_sb *, const char *,
 void bch2_add_key(struct bch_sb *, const char *, const char *, const char *);
 void bch_sb_crypt_init(struct bch_sb *sb, struct bch_sb_field_crypt *,
 		       const char *);
+void bch_crypt_default_kdf_init(struct bch_sb_field_crypt *);
 
 #endif /* _CRYPTO_H */
-- 
2.45.2