From b7e072f9b77f4c516df96e0c22ec09f8b2e76ba1 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Mon, 25 Oct 2021 19:10:42 -0700 Subject: fscrypt: improve a few comments 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@kernel.org). Link: https://lore.kernel.org/r/20211026021042.6581-1-ebiggers@kernel.org Signed-off-by: Eric Biggers --- fs/crypto/fscrypt_private.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'fs/crypto/fscrypt_private.h') diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index cb25ef0cdf1f..5b0a9e6478b5 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. */ -- cgit v1.2.3