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