blob: f34f4176c1e7c24e921ea9b0dde96e422e3edfe4 [file] [log] [blame]
 // SPDX-License-Identifier: GPL-2.0 /* * linux/fs/ext4/hash.c * * Copyright (C) 2002 by Theodore Ts'o */ #include #include #include #include #include "ext4.h" #define DELTA 0x9E3779B9 static void TEA_transform(__u32 buf[4], __u32 const in[]) { __u32 sum = 0; __u32 b0 = buf[0], b1 = buf[1]; __u32 a = in[0], b = in[1], c = in[2], d = in[3]; int n = 16; do { sum += DELTA; b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b); b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d); } while (--n); buf[0] += b0; buf[1] += b1; } /* F, G and H are basic MD4 functions: selection, majority, parity */ #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z)))) #define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z))) #define H(x, y, z) ((x) ^ (y) ^ (z)) /* * The generic round function. The application is so specific that * we don't bother protecting all the arguments with parens, as is generally * good macro practice, in favor of extra legibility. * Rotation is separate from addition to prevent recomputation */ #define ROUND(f, a, b, c, d, x, s) \ (a += f(b, c, d) + x, a = rol32(a, s)) #define K1 0 #define K2 013240474631UL #define K3 015666365641UL /* * Basic cut-down MD4 transform. Returns only 32 bits of result. */ static __u32 half_md4_transform(__u32 buf[4], __u32 const in[8]) { __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3]; /* Round 1 */ ROUND(F, a, b, c, d, in[0] + K1, 3); ROUND(F, d, a, b, c, in[1] + K1, 7); ROUND(F, c, d, a, b, in[2] + K1, 11); ROUND(F, b, c, d, a, in[3] + K1, 19); ROUND(F, a, b, c, d, in[4] + K1, 3); ROUND(F, d, a, b, c, in[5] + K1, 7); ROUND(F, c, d, a, b, in[6] + K1, 11); ROUND(F, b, c, d, a, in[7] + K1, 19); /* Round 2 */ ROUND(G, a, b, c, d, in[1] + K2, 3); ROUND(G, d, a, b, c, in[3] + K2, 5); ROUND(G, c, d, a, b, in[5] + K2, 9); ROUND(G, b, c, d, a, in[7] + K2, 13); ROUND(G, a, b, c, d, in[0] + K2, 3); ROUND(G, d, a, b, c, in[2] + K2, 5); ROUND(G, c, d, a, b, in[4] + K2, 9); ROUND(G, b, c, d, a, in[6] + K2, 13); /* Round 3 */ ROUND(H, a, b, c, d, in[3] + K3, 3); ROUND(H, d, a, b, c, in[7] + K3, 9); ROUND(H, c, d, a, b, in[2] + K3, 11); ROUND(H, b, c, d, a, in[6] + K3, 15); ROUND(H, a, b, c, d, in[1] + K3, 3); ROUND(H, d, a, b, c, in[5] + K3, 9); ROUND(H, c, d, a, b, in[0] + K3, 11); ROUND(H, b, c, d, a, in[4] + K3, 15); buf[0] += a; buf[1] += b; buf[2] += c; buf[3] += d; return buf[1]; /* "most hashed" word */ } #undef ROUND #undef K1 #undef K2 #undef K3 #undef F #undef G #undef H /* The old legacy hash */ static __u32 dx_hack_hash_unsigned(const char *name, int len) { __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9; const unsigned char *ucp = (const unsigned char *) name; while (len--) { hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373)); if (hash & 0x80000000) hash -= 0x7fffffff; hash1 = hash0; hash0 = hash; } return hash0 << 1; } static __u32 dx_hack_hash_signed(const char *name, int len) { __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9; const signed char *scp = (const signed char *) name; while (len--) { hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373)); if (hash & 0x80000000) hash -= 0x7fffffff; hash1 = hash0; hash0 = hash; } return hash0 << 1; } static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num) { __u32 pad, val; int i; const signed char *scp = (const signed char *) msg; pad = (__u32)len | ((__u32)len << 8); pad |= pad << 16; val = pad; if (len > num*4) len = num * 4; for (i = 0; i < len; i++) { val = ((int) scp[i]) + (val << 8); if ((i % 4) == 3) { *buf++ = val; val = pad; num--; } } if (--num >= 0) *buf++ = val; while (--num >= 0) *buf++ = pad; } static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num) { __u32 pad, val; int i; const unsigned char *ucp = (const unsigned char *) msg; pad = (__u32)len | ((__u32)len << 8); pad |= pad << 16; val = pad; if (len > num*4) len = num * 4; for (i = 0; i < len; i++) { val = ((int) ucp[i]) + (val << 8); if ((i % 4) == 3) { *buf++ = val; val = pad; num--; } } if (--num >= 0) *buf++ = val; while (--num >= 0) *buf++ = pad; } /* * Returns the hash of a filename. If len is 0 and name is NULL, then * this function can be used to test whether or not a hash version is * supported. * * The seed is an 4 longword (32 bits) "secret" which can be used to * uniquify a hash. If the seed is all zero's, then some default seed * may be used. * * A particular hash version specifies whether or not the seed is * represented, and whether or not the returned hash is 32 bits or 64 * bits. 32 bit hashes will return 0 for the minor hash. */ static int __ext4fs_dirhash(const struct inode *dir, const char *name, int len, struct dx_hash_info *hinfo) { __u32 hash; __u32 minor_hash = 0; const char *p; int i; __u32 in[8], buf[4]; void (*str2hashbuf)(const char *, int, __u32 *, int) = str2hashbuf_signed; /* Initialize the default seed for the hash checksum functions */ buf[0] = 0x67452301; buf[1] = 0xefcdab89; buf[2] = 0x98badcfe; buf[3] = 0x10325476; /* Check to see if the seed is all zero's */ if (hinfo->seed) { for (i = 0; i < 4; i++) { if (hinfo->seed[i]) { memcpy(buf, hinfo->seed, sizeof(buf)); break; } } } switch (hinfo->hash_version) { case DX_HASH_LEGACY_UNSIGNED: hash = dx_hack_hash_unsigned(name, len); break; case DX_HASH_LEGACY: hash = dx_hack_hash_signed(name, len); break; case DX_HASH_HALF_MD4_UNSIGNED: str2hashbuf = str2hashbuf_unsigned; fallthrough; case DX_HASH_HALF_MD4: p = name; while (len > 0) { (*str2hashbuf)(p, len, in, 8); half_md4_transform(buf, in); len -= 32; p += 32; } minor_hash = buf[2]; hash = buf[1]; break; case DX_HASH_TEA_UNSIGNED: str2hashbuf = str2hashbuf_unsigned; fallthrough; case DX_HASH_TEA: p = name; while (len > 0) { (*str2hashbuf)(p, len, in, 4); TEA_transform(buf, in); len -= 16; p += 16; } hash = buf[0]; minor_hash = buf[1]; break; case DX_HASH_SIPHASH: { struct qstr qname = QSTR_INIT(name, len); __u64 combined_hash; if (fscrypt_has_encryption_key(dir)) { combined_hash = fscrypt_fname_siphash(dir, &qname); } else { ext4_warning_inode(dir, "Siphash requires key"); return -1; } hash = (__u32)(combined_hash >> 32); minor_hash = (__u32)combined_hash; break; } default: hinfo->hash = 0; return -1; } hash = hash & ~1; if (hash == (EXT4_HTREE_EOF_32BIT << 1)) hash = (EXT4_HTREE_EOF_32BIT - 1) << 1; hinfo->hash = hash; hinfo->minor_hash = minor_hash; return 0; } int ext4fs_dirhash(const struct inode *dir, const char *name, int len, struct dx_hash_info *hinfo) { #ifdef CONFIG_UNICODE const struct unicode_map *um = dir->i_sb->s_encoding; int r, dlen; unsigned char *buff; struct qstr qstr = {.name = name, .len = len }; if (len && IS_CASEFOLDED(dir) && um && (!IS_ENCRYPTED(dir) || fscrypt_has_encryption_key(dir))) { buff = kzalloc(sizeof(char) * PATH_MAX, GFP_KERNEL); if (!buff) return -ENOMEM; dlen = utf8_casefold(um, &qstr, buff, PATH_MAX); if (dlen < 0) { kfree(buff); goto opaque_seq; } r = __ext4fs_dirhash(dir, buff, dlen, hinfo); kfree(buff); return r; } opaque_seq: #endif return __ext4fs_dirhash(dir, name, len, hinfo); }