fscrypt: remove internal key size constants

With one exception, the internal key size constants such as
FS_AES_256_XTS_KEY_SIZE are only used for the 'available_modes' array,
where they really only serve to obfuscate what the values are.  Also
some of the constants are unused, and the key sizes tend to be in the
names of the algorithms anyway.  In the past these values were also
misused, e.g. we used to have FS_AES_256_XTS_KEY_SIZE in places that
technically should have been FS_MAX_KEY_SIZE.

The exception is that FS_AES_128_ECB_KEY_SIZE is used for key
derivation.  But it's more appropriate to use
FS_KEY_DERIVATION_NONCE_SIZE for that instead.

Thus, just put the sizes directly in the 'available_modes' array.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 05e0f88c4a7032a754cdecbfcccdd85140689971..dbe797fb6fdb42f3b26fcffe55c5e4be10ba72db 100644 (file)
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -18,15 +18,7 @@
 
 /* Encryption parameters */
 #define FS_IV_SIZE                     16
-#define FS_AES_128_ECB_KEY_SIZE                16
-#define FS_AES_128_CBC_KEY_SIZE                16
-#define FS_AES_128_CTS_KEY_SIZE                16
-#define FS_AES_256_GCM_KEY_SIZE                32
-#define FS_AES_256_CBC_KEY_SIZE                32
-#define FS_AES_256_CTS_KEY_SIZE                32
-#define FS_AES_256_XTS_KEY_SIZE                64
-
-#define FS_KEY_DERIVATION_NONCE_SIZE           16
+#define FS_KEY_DERIVATION_NONCE_SIZE   16
 
 /**
  * Encryption context for inode

diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
index 0b48aa469453f1db8ce609b2a450e2e8b58e3b74..f6d6acd37b97a738474f8bcff851eadd591363f2 100644 (file)
--- a/fs/crypto/keyinfo.c
+++ b/fs/crypto/keyinfo.c
@@ -27,7 +27,7 @@ static struct crypto_shash *essiv_hash_tfm;
  *
  * Return: Zero on success; non-zero otherwise.
  */
-static int derive_key_aes(u8 deriving_key[FS_AES_128_ECB_KEY_SIZE],
+static int derive_key_aes(u8 deriving_key[FS_KEY_DERIVATION_NONCE_SIZE],
                                const struct fscrypt_key *source_key,
                                u8 derived_raw_key[FS_MAX_KEY_SIZE])
 {
@@ -52,7 +52,7 @@ static int derive_key_aes(u8 deriving_key[FS_AES_128_ECB_KEY_SIZE],
                        CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
                        crypto_req_done, &wait);
        res = crypto_skcipher_setkey(tfm, deriving_key,
-                                       FS_AES_128_ECB_KEY_SIZE);
+                                    FS_KEY_DERIVATION_NONCE_SIZE);
        if (res < 0)
                goto out;
 
@@ -100,7 +100,6 @@ static int validate_user_key(struct fscrypt_info *crypt_info,
                goto out;
        }
        master_key = (struct fscrypt_key *)ukp->data;
-       BUILD_BUG_ON(FS_AES_128_ECB_KEY_SIZE != FS_KEY_DERIVATION_NONCE_SIZE);
 
        if (master_key->size < min_keysize || master_key->size > FS_MAX_KEY_SIZE
            || master_key->size % AES_BLOCK_SIZE != 0) {
@@ -121,14 +120,10 @@ static const struct {
        const char *cipher_str;
        int keysize;
 } available_modes[] = {
-       [FS_ENCRYPTION_MODE_AES_256_XTS] = { "xts(aes)",
-                                            FS_AES_256_XTS_KEY_SIZE },
-       [FS_ENCRYPTION_MODE_AES_256_CTS] = { "cts(cbc(aes))",
-                                            FS_AES_256_CTS_KEY_SIZE },
-       [FS_ENCRYPTION_MODE_AES_128_CBC] = { "cbc(aes)",
-                                            FS_AES_128_CBC_KEY_SIZE },
-       [FS_ENCRYPTION_MODE_AES_128_CTS] = { "cts(cbc(aes))",
-                                            FS_AES_128_CTS_KEY_SIZE },
+       [FS_ENCRYPTION_MODE_AES_256_XTS]      = { "xts(aes)",           64 },
+       [FS_ENCRYPTION_MODE_AES_256_CTS]      = { "cts(cbc(aes))",      32 },
+       [FS_ENCRYPTION_MODE_AES_128_CBC]      = { "cbc(aes)",           16 },
+       [FS_ENCRYPTION_MODE_AES_128_CTS]      = { "cts(cbc(aes))",      16 },
 };
 
 static int determine_cipher_type(struct fscrypt_info *ci, struct inode *inode,