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1// SPDX-License-Identifier: GPL-2.02/*3 * linux/fs/ext4/hash.c4 *5 * Copyright (C) 2002 by Theodore Ts'o6 */7 8#include <linux/fs.h>9#include <linux/unicode.h>10#include <linux/compiler.h>11#include <linux/bitops.h>12#include "ext4.h"13 14#define DELTA 0x9E3779B915 16static void TEA_transform(__u32 buf[4], __u32 const in[])17{18 __u32 sum = 0;19 __u32 b0 = buf[0], b1 = buf[1];20 __u32 a = in[0], b = in[1], c = in[2], d = in[3];21 int n = 16;22 23 do {24 sum += DELTA;25 b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);26 b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);27 } while (--n);28 29 buf[0] += b0;30 buf[1] += b1;31}32 33/* F, G and H are basic MD4 functions: selection, majority, parity */34#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))35#define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))36#define H(x, y, z) ((x) ^ (y) ^ (z))37 38/*39 * The generic round function. The application is so specific that40 * we don't bother protecting all the arguments with parens, as is generally41 * good macro practice, in favor of extra legibility.42 * Rotation is separate from addition to prevent recomputation43 */44#define ROUND(f, a, b, c, d, x, s) \45 (a += f(b, c, d) + x, a = rol32(a, s))46#define K1 047#define K2 013240474631UL48#define K3 015666365641UL49 50/*51 * Basic cut-down MD4 transform. Returns only 32 bits of result.52 */53static __u32 half_md4_transform(__u32 buf[4], __u32 const in[8])54{55 __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];56 57 /* Round 1 */58 ROUND(F, a, b, c, d, in[0] + K1, 3);59 ROUND(F, d, a, b, c, in[1] + K1, 7);60 ROUND(F, c, d, a, b, in[2] + K1, 11);61 ROUND(F, b, c, d, a, in[3] + K1, 19);62 ROUND(F, a, b, c, d, in[4] + K1, 3);63 ROUND(F, d, a, b, c, in[5] + K1, 7);64 ROUND(F, c, d, a, b, in[6] + K1, 11);65 ROUND(F, b, c, d, a, in[7] + K1, 19);66 67 /* Round 2 */68 ROUND(G, a, b, c, d, in[1] + K2, 3);69 ROUND(G, d, a, b, c, in[3] + K2, 5);70 ROUND(G, c, d, a, b, in[5] + K2, 9);71 ROUND(G, b, c, d, a, in[7] + K2, 13);72 ROUND(G, a, b, c, d, in[0] + K2, 3);73 ROUND(G, d, a, b, c, in[2] + K2, 5);74 ROUND(G, c, d, a, b, in[4] + K2, 9);75 ROUND(G, b, c, d, a, in[6] + K2, 13);76 77 /* Round 3 */78 ROUND(H, a, b, c, d, in[3] + K3, 3);79 ROUND(H, d, a, b, c, in[7] + K3, 9);80 ROUND(H, c, d, a, b, in[2] + K3, 11);81 ROUND(H, b, c, d, a, in[6] + K3, 15);82 ROUND(H, a, b, c, d, in[1] + K3, 3);83 ROUND(H, d, a, b, c, in[5] + K3, 9);84 ROUND(H, c, d, a, b, in[0] + K3, 11);85 ROUND(H, b, c, d, a, in[4] + K3, 15);86 87 buf[0] += a;88 buf[1] += b;89 buf[2] += c;90 buf[3] += d;91 92 return buf[1]; /* "most hashed" word */93}94#undef ROUND95#undef K196#undef K297#undef K398#undef F99#undef G100#undef H101 102/* The old legacy hash */103static __u32 dx_hack_hash_unsigned(const char *name, int len)104{105 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;106 const unsigned char *ucp = (const unsigned char *) name;107 108 while (len--) {109 hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));110 111 if (hash & 0x80000000)112 hash -= 0x7fffffff;113 hash1 = hash0;114 hash0 = hash;115 }116 return hash0 << 1;117}118 119static __u32 dx_hack_hash_signed(const char *name, int len)120{121 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;122 const signed char *scp = (const signed char *) name;123 124 while (len--) {125 hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));126 127 if (hash & 0x80000000)128 hash -= 0x7fffffff;129 hash1 = hash0;130 hash0 = hash;131 }132 return hash0 << 1;133}134 135static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)136{137 __u32 pad, val;138 int i;139 const signed char *scp = (const signed char *) msg;140 141 pad = (__u32)len | ((__u32)len << 8);142 pad |= pad << 16;143 144 val = pad;145 if (len > num*4)146 len = num * 4;147 for (i = 0; i < len; i++) {148 val = ((int) scp[i]) + (val << 8);149 if ((i % 4) == 3) {150 *buf++ = val;151 val = pad;152 num--;153 }154 }155 if (--num >= 0)156 *buf++ = val;157 while (--num >= 0)158 *buf++ = pad;159}160 161static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)162{163 __u32 pad, val;164 int i;165 const unsigned char *ucp = (const unsigned char *) msg;166 167 pad = (__u32)len | ((__u32)len << 8);168 pad |= pad << 16;169 170 val = pad;171 if (len > num*4)172 len = num * 4;173 for (i = 0; i < len; i++) {174 val = ((int) ucp[i]) + (val << 8);175 if ((i % 4) == 3) {176 *buf++ = val;177 val = pad;178 num--;179 }180 }181 if (--num >= 0)182 *buf++ = val;183 while (--num >= 0)184 *buf++ = pad;185}186 187/*188 * Returns the hash of a filename. If len is 0 and name is NULL, then189 * this function can be used to test whether or not a hash version is190 * supported.191 *192 * The seed is an 4 longword (32 bits) "secret" which can be used to193 * uniquify a hash. If the seed is all zero's, then some default seed194 * may be used.195 *196 * A particular hash version specifies whether or not the seed is197 * represented, and whether or not the returned hash is 32 bits or 64198 * bits. 32 bit hashes will return 0 for the minor hash.199 */200static int __ext4fs_dirhash(const struct inode *dir, const char *name, int len,201 struct dx_hash_info *hinfo)202{203 __u32 hash;204 __u32 minor_hash = 0;205 const char *p;206 int i;207 __u32 in[8], buf[4];208 void (*str2hashbuf)(const char *, int, __u32 *, int) =209 str2hashbuf_signed;210 211 /* Initialize the default seed for the hash checksum functions */212 buf[0] = 0x67452301;213 buf[1] = 0xefcdab89;214 buf[2] = 0x98badcfe;215 buf[3] = 0x10325476;216 217 /* Check to see if the seed is all zero's */218 if (hinfo->seed) {219 for (i = 0; i < 4; i++) {220 if (hinfo->seed[i]) {221 memcpy(buf, hinfo->seed, sizeof(buf));222 break;223 }224 }225 }226 227 switch (hinfo->hash_version) {228 case DX_HASH_LEGACY_UNSIGNED:229 hash = dx_hack_hash_unsigned(name, len);230 break;231 case DX_HASH_LEGACY:232 hash = dx_hack_hash_signed(name, len);233 break;234 case DX_HASH_HALF_MD4_UNSIGNED:235 str2hashbuf = str2hashbuf_unsigned;236 fallthrough;237 case DX_HASH_HALF_MD4:238 p = name;239 while (len > 0) {240 (*str2hashbuf)(p, len, in, 8);241 half_md4_transform(buf, in);242 len -= 32;243 p += 32;244 }245 minor_hash = buf[2];246 hash = buf[1];247 break;248 case DX_HASH_TEA_UNSIGNED:249 str2hashbuf = str2hashbuf_unsigned;250 fallthrough;251 case DX_HASH_TEA:252 p = name;253 while (len > 0) {254 (*str2hashbuf)(p, len, in, 4);255 TEA_transform(buf, in);256 len -= 16;257 p += 16;258 }259 hash = buf[0];260 minor_hash = buf[1];261 break;262 case DX_HASH_SIPHASH:263 {264 struct qstr qname = QSTR_INIT(name, len);265 __u64 combined_hash;266 267 if (fscrypt_has_encryption_key(dir)) {268 combined_hash = fscrypt_fname_siphash(dir, &qname);269 } else {270 ext4_warning_inode(dir, "Siphash requires key");271 return -1;272 }273 274 hash = (__u32)(combined_hash >> 32);275 minor_hash = (__u32)combined_hash;276 break;277 }278 default:279 hinfo->hash = 0;280 hinfo->minor_hash = 0;281 ext4_warning(dir->i_sb,282 "invalid/unsupported hash tree version %u",283 hinfo->hash_version);284 return -EINVAL;285 }286 hash = hash & ~1;287 if (hash == (EXT4_HTREE_EOF_32BIT << 1))288 hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;289 hinfo->hash = hash;290 hinfo->minor_hash = minor_hash;291 return 0;292}293 294int ext4fs_dirhash(const struct inode *dir, const char *name, int len,295 struct dx_hash_info *hinfo)296{297#if IS_ENABLED(CONFIG_UNICODE)298 const struct unicode_map *um = dir->i_sb->s_encoding;299 int r, dlen;300 unsigned char *buff;301 struct qstr qstr = {.name = name, .len = len };302 303 if (len && IS_CASEFOLDED(dir) &&304 (!IS_ENCRYPTED(dir) || fscrypt_has_encryption_key(dir))) {305 buff = kzalloc(sizeof(char) * PATH_MAX, GFP_KERNEL);306 if (!buff)307 return -ENOMEM;308 309 dlen = utf8_casefold(um, &qstr, buff, PATH_MAX);310 if (dlen < 0) {311 kfree(buff);312 goto opaque_seq;313 }314 315 r = __ext4fs_dirhash(dir, buff, dlen, hinfo);316 317 kfree(buff);318 return r;319 }320opaque_seq:321#endif322 return __ext4fs_dirhash(dir, name, len, hinfo);323}324