From: Eric Biggers <ebiggers@kernel.org>
To: linux-f2fs-devel@lists.sourceforge.net
Cc: linux-fscrypt@vger.kernel.org,
Gabriel Krisman Bertazi <krisman@collabora.com>,
Daniel Rosenberg <drosen@google.com>
Subject: [f2fs-dev] [RFC PATCH 4/4] f2fs: Handle casefolding with Encryption (INCOMPLETE)
Date: Thu, 7 May 2020 00:59:05 -0700 [thread overview]
Message-ID: <20200507075905.953777-5-ebiggers@kernel.org> (raw)
In-Reply-To: <20200507075905.953777-1-ebiggers@kernel.org>
From: Eric Biggers <ebiggers@google.com>
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.
[Based on patches from Daniel Rosenberg <drosen@google.com>
and Jaegeuk Kim <jaegeuk@kernel.org>. This patch is incomplete as it
doesn't include the generic_set_encrypted_ci_d_ops(). This patch just
shows the other changes based on top of the f2fs_filename rework.]
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/f2fs/dir.c | 63 ++++++++++++++++++++++++++++++++++++++--------
fs/f2fs/f2fs.h | 8 +++---
fs/f2fs/hash.c | 11 +++++++-
fs/f2fs/recovery.c | 12 ++++++++-
4 files changed, 79 insertions(+), 15 deletions(-)
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 29f70f2295cce8..eea9458a37b384 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -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 <linux/sched/signal.h>
@@ -217,9 +218,28 @@ static bool f2fs_match_ci_name(const struct inode *dir, const struct qstr *name,
{
const struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
const struct unicode_map *um = sbi->s_encoding;
+ struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len);
struct qstr entry = QSTR_INIT(de_name, de_name_len);
int res;
+ if (IS_ENCRYPTED(dir)) {
+ const struct fscrypt_str encrypted_name =
+ FSTR_INIT((u8 *)de_name, de_name_len);
+
+ if (WARN_ON_ONCE(!fscrypt_has_encryption_key(dir)))
+ return false;
+
+ decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL);
+ if (!decrypted_name.name)
+ return false;
+ res = fscrypt_fname_disk_to_usr(dir, 0, 0, &encrypted_name,
+ &decrypted_name);
+ if (res < 0)
+ goto out;
+ entry.name = decrypted_name.name;
+ entry.len = decrypted_name.len;
+ }
+
res = utf8_strncasecmp_folded(um, name, &entry);
if (res < 0) {
/*
@@ -227,9 +247,12 @@ static bool f2fs_match_ci_name(const struct inode *dir, const struct qstr *name,
* fall back to treating them as opaque byte sequences.
*/
if (f2fs_has_strict_mode(sbi) || name->len != entry.len)
- return false;
- return !memcmp(name->name, entry.name, name->len);
+ res = 1;
+ else
+ res = memcmp(name->name, entry.name, name->len);
}
+out:
+ kfree(decrypted_name.name);
return res == 0;
}
#endif /* CONFIG_UNICODE */
@@ -454,17 +477,39 @@ void f2fs_set_link(struct inode *dir, struct f2fs_dir_entry *de,
f2fs_put_page(page, 1);
}
-static void init_dent_inode(const struct f2fs_filename *fname,
+static void init_dent_inode(struct inode *dir, struct inode *inode,
+ const struct f2fs_filename *fname,
struct page *ipage)
{
struct f2fs_inode *ri;
+ if (!fname) /* tmpfile case? */
+ return;
+
f2fs_wait_on_page_writeback(ipage, NODE, true, true);
/* copy name info. to this inode page */
ri = F2FS_INODE(ipage);
ri->i_namelen = cpu_to_le32(fname->disk_name.len);
memcpy(ri->i_name, fname->disk_name.name, fname->disk_name.len);
+ if (IS_ENCRYPTED(dir)) {
+ file_set_enc_name(inode);
+ /*
+ * Roll-forward recovery doesn't have encryption keys available,
+ * so it can't compute the dirhash for encrypted+casefolded
+ * filenames. Append it to i_name if possible. Else, disable
+ * roll-forward recovery of the dentry (i.e., make fsync'ing the
+ * file force a checkpoint) by setting LOST_PINO.
+ */
+ if (IS_CASEFOLDED(dir)) {
+ if (fname->disk_name.len + sizeof(f2fs_hash_t) <=
+ F2FS_NAME_LEN)
+ put_unaligned(fname->hash,
+ &ri->i_name[fname->disk_name.len]);
+ else
+ file_lost_pino(inode);
+ }
+ }
set_page_dirty(ipage);
}
@@ -547,11 +592,7 @@ struct page *f2fs_init_inode_metadata(struct inode *inode, struct inode *dir,
return page;
}
- if (fname) {
- init_dent_inode(fname, page);
- if (IS_ENCRYPTED(dir))
- file_set_enc_name(inode);
- }
+ init_dent_inode(dir, inode, fname, page);
/*
* This file should be checkpointed during fsync.
@@ -1116,7 +1157,8 @@ static int f2fs_d_compare(const struct dentry *dentry, unsigned int len,
struct qstr entry = QSTR_INIT(str, len);
int res;
- if (!dir || !IS_CASEFOLDED(dir))
+ if (!dir || !IS_CASEFOLDED(dir) ||
+ (IS_ENCRYPTED(dir) && !fscrypt_has_encryption_key(dir)))
goto fallback;
res = utf8_strncasecmp(sbi->s_encoding, name, &entry);
@@ -1139,7 +1181,8 @@ static int f2fs_d_hash(const struct dentry *dentry, struct qstr *str)
unsigned char *norm;
int len, ret = 0;
- if (!inode || !IS_CASEFOLDED(inode))
+ if (!inode || !IS_CASEFOLDED(inode) ||
+ (IS_ENCRYPTED(inode) && !fscrypt_has_encryption_key(inode)))
return 0;
norm = f2fs_kmalloc(sbi, PATH_MAX, GFP_ATOMIC);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 1df50d9224bb71..1c01d6b87e936f 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -534,9 +534,11 @@ struct f2fs_filename {
#ifdef CONFIG_UNICODE
/*
* For casefolded directories: the casefolded name, but it's left NULL
- * if the original name is not valid Unicode or if the filesystem is
- * doing an internal operation where usr_fname is also NULL. In these
- * cases we fall back to treating the name as an opaque byte sequence.
+ * if the original name is not valid Unicode, if the directory is both
+ * casefolded and encrypted and its encryption key is unavailable, or if
+ * the filesystem is doing an internal operation where usr_fname is also
+ * NULL. In all these cases we fall back to treating the name as an
+ * opaque byte sequence.
*/
struct fscrypt_str cf_name;
#endif
diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c
index e5997919472d4f..f9b706495d1d62 100644
--- a/fs/f2fs/hash.c
+++ b/fs/f2fs/hash.c
@@ -112,7 +112,9 @@ 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) {
@@ -122,6 +124,13 @@ 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));
diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index ae5310f02e7ff1..c762a9e4300620 100644
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -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;
--
2.26.2
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next prev parent reply other threads:[~2020-05-07 8:02 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-07 7:59 [f2fs-dev] [PATCH 0/4] f2fs: rework filename handling Eric Biggers
2020-05-07 7:59 ` [f2fs-dev] [PATCH 1/4] f2fs: don't leak filename in f2fs_try_convert_inline_dir() Eric Biggers
2020-05-08 8:25 ` Chao Yu
2020-05-07 7:59 ` [f2fs-dev] [PATCH 2/4] f2fs: split f2fs_d_compare() from f2fs_match_name() Eric Biggers
2020-05-11 2:47 ` Chao Yu
2020-05-07 7:59 ` [f2fs-dev] [PATCH 3/4] f2fs: rework filename handling Eric Biggers
2020-05-25 8:12 ` Chao Yu
2020-05-25 15:10 ` Jaegeuk Kim
2020-05-07 7:59 ` Eric Biggers [this message]
2020-05-08 2:55 ` [f2fs-dev] [RFC PATCH 4/4] f2fs: Handle casefolding with Encryption (INCOMPLETE) Eric Biggers
2020-05-07 13:09 ` [f2fs-dev] [PATCH 0/4] f2fs: rework filename handling Jaegeuk Kim
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