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
![]() |