cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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hash.c (3080B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * fs/f2fs/hash.c
      4 *
      5 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
      6 *             http://www.samsung.com/
      7 *
      8 * Portions of this code from linux/fs/ext3/hash.c
      9 *
     10 * Copyright (C) 2002 by Theodore Ts'o
     11 */
     12#include <linux/types.h>
     13#include <linux/fs.h>
     14#include <linux/f2fs_fs.h>
     15#include <linux/pagemap.h>
     16#include <linux/unicode.h>
     17
     18#include "f2fs.h"
     19
     20/*
     21 * Hashing code copied from ext3
     22 */
     23#define DELTA 0x9E3779B9
     24
     25static void TEA_transform(unsigned int buf[4], unsigned int const in[])
     26{
     27	__u32 sum = 0;
     28	__u32 b0 = buf[0], b1 = buf[1];
     29	__u32 a = in[0], b = in[1], c = in[2], d = in[3];
     30	int n = 16;
     31
     32	do {
     33		sum += DELTA;
     34		b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
     35		b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
     36	} while (--n);
     37
     38	buf[0] += b0;
     39	buf[1] += b1;
     40}
     41
     42static void str2hashbuf(const unsigned char *msg, size_t len,
     43				unsigned int *buf, int num)
     44{
     45	unsigned pad, val;
     46	int i;
     47
     48	pad = (__u32)len | ((__u32)len << 8);
     49	pad |= pad << 16;
     50
     51	val = pad;
     52	if (len > num * 4)
     53		len = num * 4;
     54	for (i = 0; i < len; i++) {
     55		if ((i % 4) == 0)
     56			val = pad;
     57		val = msg[i] + (val << 8);
     58		if ((i % 4) == 3) {
     59			*buf++ = val;
     60			val = pad;
     61			num--;
     62		}
     63	}
     64	if (--num >= 0)
     65		*buf++ = val;
     66	while (--num >= 0)
     67		*buf++ = pad;
     68}
     69
     70static u32 TEA_hash_name(const u8 *p, size_t len)
     71{
     72	__u32 in[8], buf[4];
     73
     74	/* Initialize the default seed for the hash checksum functions */
     75	buf[0] = 0x67452301;
     76	buf[1] = 0xefcdab89;
     77	buf[2] = 0x98badcfe;
     78	buf[3] = 0x10325476;
     79
     80	while (1) {
     81		str2hashbuf(p, len, in, 4);
     82		TEA_transform(buf, in);
     83		p += 16;
     84		if (len <= 16)
     85			break;
     86		len -= 16;
     87	}
     88	return buf[0] & ~F2FS_HASH_COL_BIT;
     89}
     90
     91/*
     92 * Compute @fname->hash.  For all directories, @fname->disk_name must be set.
     93 * For casefolded directories, @fname->usr_fname must be set, and also
     94 * @fname->cf_name if the filename is valid Unicode and is not "." or "..".
     95 */
     96void f2fs_hash_filename(const struct inode *dir, struct f2fs_filename *fname)
     97{
     98	const u8 *name = fname->disk_name.name;
     99	size_t len = fname->disk_name.len;
    100
    101	WARN_ON_ONCE(!name);
    102
    103	if (is_dot_dotdot(name, len)) {
    104		fname->hash = 0;
    105		return;
    106	}
    107
    108#if IS_ENABLED(CONFIG_UNICODE)
    109	if (IS_CASEFOLDED(dir)) {
    110		/*
    111		 * If the casefolded name is provided, hash it instead of the
    112		 * on-disk name.  If the casefolded name is *not* provided, that
    113		 * should only be because the name wasn't valid Unicode or was
    114		 * "." or "..", so fall back to treating the name as an opaque
    115		 * byte sequence.  Note that to handle encrypted directories,
    116		 * the fallback must use usr_fname (plaintext) rather than
    117		 * disk_name (ciphertext).
    118		 */
    119		WARN_ON_ONCE(!fname->usr_fname->name);
    120		if (fname->cf_name.name) {
    121			name = fname->cf_name.name;
    122			len = fname->cf_name.len;
    123		} else {
    124			name = fname->usr_fname->name;
    125			len = fname->usr_fname->len;
    126		}
    127		if (IS_ENCRYPTED(dir)) {
    128			struct qstr tmp = QSTR_INIT(name, len);
    129
    130			fname->hash =
    131				cpu_to_le32(fscrypt_fname_siphash(dir, &tmp));
    132			return;
    133		}
    134	}
    135#endif
    136	fname->hash = cpu_to_le32(TEA_hash_name(name, len));
    137}