From: Eric Biggers <ebiggers@xxxxxxxxxx>
Improve a few comments. These were extracted from the patch
"fscrypt: add support for hardware-wrapped keys"
(https://lore.kernel.org/r/20211021181608.54127-4-ebiggers@xxxxxxxxxx).
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
fs/crypto/fscrypt_private.h | 11 ++++++++++-
fs/crypto/keysetup.c | 5 +++--
2 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index cb25ef0cdf1f3..5b0a9e6478b5d 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -20,6 +20,11 @@
#define FSCRYPT_FILE_NONCE_SIZE 16
+/*
+ * Minimum size of an fscrypt master key. Note: a longer key will be required
+ * if ciphers with a 256-bit security strength are used. This is just the
+ * absolute minimum, which applies when only 128-bit encryption is used.
+ */
#define FSCRYPT_MIN_KEY_SIZE 16
#define FSCRYPT_CONTEXT_V1 1
@@ -413,7 +418,11 @@ struct fscrypt_master_key_secret {
*/
struct fscrypt_hkdf hkdf;
- /* Size of the raw key in bytes. Set even if ->raw isn't set. */
+ /*
+ * Size of the raw key in bytes. This remains set even if ->raw was
+ * zeroized due to no longer being needed. I.e. we still remember the
+ * size of the key even if we don't need to remember the key itself.
+ */
u32 size;
/* For v1 policy keys: the raw key. Wiped for v2 policy keys. */
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index 89cd533a88bff..eede186b04ce3 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -122,8 +122,9 @@ fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
/*
* Prepare the crypto transform object or blk-crypto key in @prep_key, given the
- * raw key, encryption mode, and flag indicating which encryption implementation
- * (fs-layer or blk-crypto) will be used.
+ * raw key, encryption mode (@ci->ci_mode), flag indicating which encryption
+ * implementation (fs-layer or blk-crypto) will be used (@ci->ci_inlinecrypt),
+ * and IV generation method (@ci->ci_policy.flags).
*/
int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key,
const u8 *raw_key, const struct fscrypt_info *ci)
base-commit: 7f595d6a6cdc336834552069a2e0a4f6d4756ddf
--
2.33.1
|