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authorDaniel Rosenberg <drosen@google.com>2020-11-19 06:09:04 +0000
committerJaegeuk Kim <jaegeuk@kernel.org>2020-12-02 22:00:21 -0800
commit7ad08a58bf67594057362e45cbddd3e27e53e557 (patch)
treecc8f281ee95421efe8cb34564938b466141ee506 /fs/f2fs/hash.c
parentbb9cd9106b22b4fc5ff8d78a752be8a4ba2cbba5 (diff)
f2fs: Handle casefolding with Encryption
Expand f2fs's casefolding support to include encrypted directories. To index casefolded+encrypted directories, we use the SipHash of the casefolded name, keyed by a key derived from the directory's fscrypt master key. This ensures that the dirhash doesn't leak information about the plaintext filenames. Encryption keys are unavailable during roll-forward recovery, so we can't compute the dirhash when recovering a new dentry in an encrypted + casefolded directory. To avoid having to force a checkpoint when a new file is fsync'ed, store the dirhash on-disk appended to i_name. This patch incorporates work by Eric Biggers <ebiggers@google.com> and Jaegeuk Kim <jaegeuk@kernel.org>. Co-developed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Daniel Rosenberg <drosen@google.com> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs/hash.c')
-rw-r--r--fs/f2fs/hash.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c
index de841aaf3c43..e3beac546c63 100644
--- a/fs/f2fs/hash.c
+++ b/fs/f2fs/hash.c
@@ -111,7 +111,9 @@ void f2fs_hash_filename(const struct inode *dir, struct f2fs_filename *fname)
* If the casefolded name is provided, hash it instead of the
* on-disk name. If the casefolded name is *not* provided, that
* should only be because the name wasn't valid Unicode, so fall
- * back to treating the name as an opaque byte sequence.
+ * back to treating the name as an opaque byte sequence. Note
+ * that to handle encrypted directories, the fallback must use
+ * usr_fname (plaintext) rather than disk_name (ciphertext).
*/
WARN_ON_ONCE(!fname->usr_fname->name);
if (fname->cf_name.name) {
@@ -121,6 +123,13 @@ void f2fs_hash_filename(const struct inode *dir, struct f2fs_filename *fname)
name = fname->usr_fname->name;
len = fname->usr_fname->len;
}
+ if (IS_ENCRYPTED(dir)) {
+ struct qstr tmp = QSTR_INIT(name, len);
+
+ fname->hash =
+ cpu_to_le32(fscrypt_fname_siphash(dir, &tmp));
+ return;
+ }
}
#endif
fname->hash = cpu_to_le32(TEA_hash_name(name, len));