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7ad08a58bf
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>
137 lines
3.0 KiB
C
137 lines
3.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* fs/f2fs/hash.c
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*
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* Copyright (c) 2012 Samsung Electronics Co., Ltd.
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* http://www.samsung.com/
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*
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* Portions of this code from linux/fs/ext3/hash.c
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*
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* Copyright (C) 2002 by Theodore Ts'o
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*/
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#include <linux/types.h>
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#include <linux/fs.h>
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#include <linux/f2fs_fs.h>
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#include <linux/pagemap.h>
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#include <linux/unicode.h>
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#include "f2fs.h"
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/*
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* Hashing code copied from ext3
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*/
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#define DELTA 0x9E3779B9
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static void TEA_transform(unsigned int buf[4], unsigned int const in[])
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{
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__u32 sum = 0;
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__u32 b0 = buf[0], b1 = buf[1];
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__u32 a = in[0], b = in[1], c = in[2], d = in[3];
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int n = 16;
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do {
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sum += DELTA;
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b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
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b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
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} while (--n);
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buf[0] += b0;
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buf[1] += b1;
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}
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static void str2hashbuf(const unsigned char *msg, size_t len,
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unsigned int *buf, int num)
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{
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unsigned pad, val;
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int i;
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pad = (__u32)len | ((__u32)len << 8);
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pad |= pad << 16;
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val = pad;
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if (len > num * 4)
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len = num * 4;
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for (i = 0; i < len; i++) {
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if ((i % 4) == 0)
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val = pad;
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val = msg[i] + (val << 8);
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if ((i % 4) == 3) {
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*buf++ = val;
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val = pad;
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num--;
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}
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}
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if (--num >= 0)
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*buf++ = val;
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while (--num >= 0)
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*buf++ = pad;
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}
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static u32 TEA_hash_name(const u8 *p, size_t len)
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{
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__u32 in[8], buf[4];
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/* Initialize the default seed for the hash checksum functions */
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buf[0] = 0x67452301;
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buf[1] = 0xefcdab89;
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buf[2] = 0x98badcfe;
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buf[3] = 0x10325476;
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while (1) {
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str2hashbuf(p, len, in, 4);
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TEA_transform(buf, in);
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p += 16;
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if (len <= 16)
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break;
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len -= 16;
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}
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return buf[0] & ~F2FS_HASH_COL_BIT;
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}
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/*
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* Compute @fname->hash. For all directories, @fname->disk_name must be set.
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* For casefolded directories, @fname->usr_fname must be set, and also
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* @fname->cf_name if the filename is valid Unicode.
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*/
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void f2fs_hash_filename(const struct inode *dir, struct f2fs_filename *fname)
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{
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const u8 *name = fname->disk_name.name;
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size_t len = fname->disk_name.len;
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WARN_ON_ONCE(!name);
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if (is_dot_dotdot(name, len)) {
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fname->hash = 0;
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return;
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}
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#ifdef CONFIG_UNICODE
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if (IS_CASEFOLDED(dir)) {
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/*
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* If the casefolded name is provided, hash it instead of the
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* on-disk name. If the casefolded name is *not* provided, that
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* should only be because the name wasn't valid Unicode, so fall
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* back to treating the name as an opaque byte sequence. Note
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* that to handle encrypted directories, the fallback must use
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* usr_fname (plaintext) rather than disk_name (ciphertext).
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*/
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WARN_ON_ONCE(!fname->usr_fname->name);
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if (fname->cf_name.name) {
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name = fname->cf_name.name;
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len = fname->cf_name.len;
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} else {
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name = fname->usr_fname->name;
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len = fname->usr_fname->len;
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}
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if (IS_ENCRYPTED(dir)) {
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struct qstr tmp = QSTR_INIT(name, len);
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fname->hash =
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cpu_to_le32(fscrypt_fname_siphash(dir, &tmp));
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return;
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}
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}
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#endif
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fname->hash = cpu_to_le32(TEA_hash_name(name, len));
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}
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