At present, setup_per_mode_enc_key() tries to find, within an array of
mode keys in the master key, an already prepared key, and if it doesn't
find a pre-prepared key, sets up a new one. This caching is not super
clear, at least to me, and splitting this function makes it clearer.
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@xxxxxxxxxx>
---
fs/crypto/keysetup.c | 59 +++++++++++++++++++++++++++-----------------
1 file changed, 36 insertions(+), 23 deletions(-)
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index 727d473b6b03..69bd27b7e9d8 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -184,34 +184,24 @@ int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key)
return fscrypt_prepare_key(&ci->ci_enc_key, raw_key, ci);
}
-static int setup_per_mode_enc_key(struct fscrypt_info *ci,
- struct fscrypt_master_key *mk,
- struct fscrypt_prepared_key *keys,
- u8 hkdf_context, bool include_fs_uuid)
+static int setup_new_mode_prepared_key(struct fscrypt_master_key *mk,
+ struct fscrypt_prepared_key *prep_key,
+ const struct fscrypt_info *ci,
+ u8 hkdf_context, bool include_fs_uuid)
{
const struct inode *inode = ci->ci_inode;
const struct super_block *sb = inode->i_sb;
struct fscrypt_mode *mode = ci->ci_mode;
const u8 mode_num = mode - fscrypt_modes;
- struct fscrypt_prepared_key *prep_key;
u8 mode_key[FSCRYPT_MAX_KEY_SIZE];
u8 hkdf_info[sizeof(mode_num) + sizeof(sb->s_uuid)];
unsigned int hkdf_infolen = 0;
int err;
- if (WARN_ON_ONCE(mode_num > FSCRYPT_MODE_MAX))
- return -EINVAL;
-
- prep_key = &keys[mode_num];
- if (fscrypt_is_key_prepared(prep_key, ci)) {
- ci->ci_enc_key = *prep_key;
- return 0;
- }
-
mutex_lock(&fscrypt_mode_key_setup_mutex);
if (fscrypt_is_key_prepared(prep_key, ci))
- goto done_unlock;
+ goto out_unlock;
BUILD_BUG_ON(sizeof(mode_num) != 1);
BUILD_BUG_ON(sizeof(sb->s_uuid) != 16);
@@ -229,16 +219,39 @@ static int setup_per_mode_enc_key(struct fscrypt_info *ci,
goto out_unlock;
err = fscrypt_prepare_key(prep_key, mode_key, ci);
memzero_explicit(mode_key, mode->keysize);
- if (err)
- goto out_unlock;
-done_unlock:
- ci->ci_enc_key = *prep_key;
- err = 0;
+
out_unlock:
mutex_unlock(&fscrypt_mode_key_setup_mutex);
return err;
}
+static int find_mode_prepared_key(struct fscrypt_info *ci,
+ struct fscrypt_master_key *mk,
+ struct fscrypt_prepared_key *keys,
+ u8 hkdf_context, bool include_fs_uuid)
+{
+ struct fscrypt_mode *mode = ci->ci_mode;
+ const u8 mode_num = mode - fscrypt_modes;
+ struct fscrypt_prepared_key *prep_key;
+ int err;
+
+ if (WARN_ON_ONCE(mode_num > FSCRYPT_MODE_MAX))
+ return -EINVAL;
+
+ prep_key = &keys[mode_num];
+ if (fscrypt_is_key_prepared(prep_key, ci)) {
+ ci->ci_enc_key = *prep_key;
+ return 0;
+ }
+ err = setup_new_mode_prepared_key(mk, prep_key, ci, hkdf_context,
+ include_fs_uuid);
+ if (err)
+ return err;
+
+ ci->ci_enc_key = *prep_key;
+ return 0;
+}
+
/*
* Derive a SipHash key from the given fscrypt master key and the given
* application-specific information string.
@@ -294,7 +307,7 @@ static int fscrypt_setup_iv_ino_lblk_32_key(struct fscrypt_info *ci,
{
int err;
- err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_32_keys,
+ err = find_mode_prepared_key(ci, mk, mk->mk_iv_ino_lblk_32_keys,
HKDF_CONTEXT_IV_INO_LBLK_32_KEY, true);
if (err)
return err;
@@ -344,7 +357,7 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci,
* encryption key. This ensures that the master key is
* consistently used only for HKDF, avoiding key reuse issues.
*/
- err = setup_per_mode_enc_key(ci, mk, mk->mk_direct_keys,
+ err = find_mode_prepared_key(ci, mk, mk->mk_direct_keys,
HKDF_CONTEXT_DIRECT_KEY, false);
} else if (ci->ci_policy.v2.flags &
FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) {
@@ -354,7 +367,7 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci,
* the IVs. This format is optimized for use with inline
* encryption hardware compliant with the UFS standard.
*/
- err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_64_keys,
+ err = find_mode_prepared_key(ci, mk, mk->mk_iv_ino_lblk_64_keys,
HKDF_CONTEXT_IV_INO_LBLK_64_KEY,
true);
} else if (ci->ci_policy.v2.flags &
--
2.40.0
|