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| author | Eric Biggers <ebiggers@google.com> | 2022-04-05 04:09:14 +0300 |
|---|---|---|
| committer | Eric Biggers <ebiggers@google.com> | 2022-04-14 01:03:09 +0300 |
| commit | 63cec1389e116ae0e2a15e612a5b49651e04be3f (patch) | |
| tree | c1d31f842262e5de906e5845f3c2bb15736a25ad /fs/crypto/fname.c | |
| parent | ce522ba9ef7e2d9fb22a39eb3371c0c64e2a433e (diff) | |
| download | linux-63cec1389e116ae0e2a15e612a5b49651e04be3f.tar.xz | |
fscrypt: split up FS_CRYPTO_BLOCK_SIZE
FS_CRYPTO_BLOCK_SIZE is neither the filesystem block size nor the
granularity of encryption. Rather, it defines two logically separate
constraints that both arise from the block size of the AES cipher:
- The alignment required for the lengths of file contents blocks
- The minimum input/output length for the filenames encryption modes
Since there are way too many things called the "block size", and the
connection with the AES block size is not easily understood, split
FS_CRYPTO_BLOCK_SIZE into two constants FSCRYPT_CONTENTS_ALIGNMENT and
FSCRYPT_FNAME_MIN_MSG_LEN that more clearly describe what they are.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220405010914.18519-1-ebiggers@kernel.org
Diffstat (limited to 'fs/crypto/fname.c')
| -rw-r--r-- | fs/crypto/fname.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c index a9be4bc74a94..14e0ef5e9a20 100644 --- a/fs/crypto/fname.c +++ b/fs/crypto/fname.c @@ -19,6 +19,13 @@ #include "fscrypt_private.h" /* + * The minimum message length (input and output length), in bytes, for all + * filenames encryption modes. Filenames shorter than this will be zero-padded + * before being encrypted. + */ +#define FSCRYPT_FNAME_MIN_MSG_LEN 16 + +/* * struct fscrypt_nokey_name - identifier for directory entry when key is absent * * When userspace lists an encrypted directory without access to the key, the @@ -267,7 +274,7 @@ bool fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, if (orig_len > max_len) return false; - encrypted_len = max(orig_len, (u32)FS_CRYPTO_BLOCK_SIZE); + encrypted_len = max_t(u32, orig_len, FSCRYPT_FNAME_MIN_MSG_LEN); encrypted_len = round_up(encrypted_len, padding); *encrypted_len_ret = min(encrypted_len, max_len); return true; @@ -350,7 +357,7 @@ int fscrypt_fname_disk_to_usr(const struct inode *inode, return 0; } - if (iname->len < FS_CRYPTO_BLOCK_SIZE) + if (iname->len < FSCRYPT_FNAME_MIN_MSG_LEN) return -EUCLEAN; if (fscrypt_has_encryption_key(inode)) |