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f2fs: Handle casefolding with Encryption

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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>
This commit is contained in:
Daniel Rosenberg
2020-11-19 06:09:04 +00:00
committed by Jaegeuk Kim
parent 04d57a86ea
commit 2ea369bdcc
6 changed files with 107 additions and 34 deletions
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12
fs/f2fs/recovery.c
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@@ -5,6 +5,7 @@
* Copyright (c) 2012 Samsung Electronics Co., Ltd.
* http://www.samsung.com/
*/
#include <asm/unaligned.h>
#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include "f2fs.h"
@@ -128,7 +129,16 @@ static int init_recovered_filename(const struct inode *dir,
}
/* Compute the hash of the filename */
if (IS_CASEFOLDED(dir)) {
if (IS_ENCRYPTED(dir) && IS_CASEFOLDED(dir)) {
/*
* In this case the hash isn't computable without the key, so it
* was saved on-disk.
*/
if (fname->disk_name.len + sizeof(f2fs_hash_t) > F2FS_NAME_LEN)
return -EINVAL;
fname->hash = get_unaligned((f2fs_hash_t *)
&raw_inode->i_name[fname->disk_name.len]);
} else if (IS_CASEFOLDED(dir)) {
err = f2fs_init_casefolded_name(dir, fname);
if (err)
return err;