^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0-or-later
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) * mst.c - NTFS multi sector transfer protection handling code. Part of the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) * Linux-NTFS project.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) * Copyright (c) 2001-2004 Anton Altaparmakov
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) #include "ntfs.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) * post_read_mst_fixup - deprotect multi sector transfer protected data
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) * @b: pointer to the data to deprotect
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) * @size: size in bytes of @b
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) * Perform the necessary post read multi sector transfer fixup and detect the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) * presence of incomplete multi sector transfers. - In that case, overwrite the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) * magic of the ntfs record header being processed with "BAAD" (in memory only!)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) * and abort processing.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) * Return 0 on success and -EINVAL on error ("BAAD" magic will be present).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) * NOTE: We consider the absence / invalidity of an update sequence array to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) * mean that the structure is not protected at all and hence doesn't need to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) * be fixed up. Thus, we return success and not failure in this case. This is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) * in contrast to pre_write_mst_fixup(), see below.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) int post_read_mst_fixup(NTFS_RECORD *b, const u32 size)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) u16 usa_ofs, usa_count, usn;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) u16 *usa_pos, *data_pos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) /* Setup the variables. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) usa_ofs = le16_to_cpu(b->usa_ofs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) /* Decrement usa_count to get number of fixups. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) usa_count = le16_to_cpu(b->usa_count) - 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) /* Size and alignment checks. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) if ( size & (NTFS_BLOCK_SIZE - 1) ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) usa_ofs & 1 ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) usa_ofs + (usa_count * 2) > size ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) (size >> NTFS_BLOCK_SIZE_BITS) != usa_count)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) /* Position of usn in update sequence array. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) usa_pos = (u16*)b + usa_ofs/sizeof(u16);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) * The update sequence number which has to be equal to each of the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) * u16 values before they are fixed up. Note no need to care for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) * endianness since we are comparing and moving data for on disk
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) * structures which means the data is consistent. - If it is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) * consistenty the wrong endianness it doesn't make any difference.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) usn = *usa_pos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) * Position in protected data of first u16 that needs fixing up.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) data_pos = (u16*)b + NTFS_BLOCK_SIZE/sizeof(u16) - 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) * Check for incomplete multi sector transfer(s).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) while (usa_count--) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) if (*data_pos != usn) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) * Incomplete multi sector transfer detected! )-:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) * Set the magic to "BAAD" and return failure.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) * Note that magic_BAAD is already converted to le32.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) b->magic = magic_BAAD;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) return -EINVAL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) data_pos += NTFS_BLOCK_SIZE/sizeof(u16);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) /* Re-setup the variables. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) usa_count = le16_to_cpu(b->usa_count) - 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) data_pos = (u16*)b + NTFS_BLOCK_SIZE/sizeof(u16) - 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) /* Fixup all sectors. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) while (usa_count--) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) * Increment position in usa and restore original data from
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) * the usa into the data buffer.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) *data_pos = *(++usa_pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) /* Increment position in data as well. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) data_pos += NTFS_BLOCK_SIZE/sizeof(u16);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) * pre_write_mst_fixup - apply multi sector transfer protection
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) * @b: pointer to the data to protect
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) * @size: size in bytes of @b
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) * Perform the necessary pre write multi sector transfer fixup on the data
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) * pointer to by @b of @size.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) * Return 0 if fixup applied (success) or -EINVAL if no fixup was performed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) * (assumed not needed). This is in contrast to post_read_mst_fixup() above.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) * NOTE: We consider the absence / invalidity of an update sequence array to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) * mean that the structure is not subject to protection and hence doesn't need
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) * to be fixed up. This means that you have to create a valid update sequence
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) * array header in the ntfs record before calling this function, otherwise it
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) * will fail (the header needs to contain the position of the update sequence
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) * array together with the number of elements in the array). You also need to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) * initialise the update sequence number before calling this function
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) * otherwise a random word will be used (whatever was in the record at that
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) * position at that time).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) int pre_write_mst_fixup(NTFS_RECORD *b, const u32 size)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) le16 *usa_pos, *data_pos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) u16 usa_ofs, usa_count, usn;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) le16 le_usn;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) /* Sanity check + only fixup if it makes sense. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) if (!b || ntfs_is_baad_record(b->magic) ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) ntfs_is_hole_record(b->magic))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) return -EINVAL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) /* Setup the variables. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) usa_ofs = le16_to_cpu(b->usa_ofs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) /* Decrement usa_count to get number of fixups. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) usa_count = le16_to_cpu(b->usa_count) - 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) /* Size and alignment checks. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) if ( size & (NTFS_BLOCK_SIZE - 1) ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) usa_ofs & 1 ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) usa_ofs + (usa_count * 2) > size ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) (size >> NTFS_BLOCK_SIZE_BITS) != usa_count)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) return -EINVAL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) /* Position of usn in update sequence array. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) usa_pos = (le16*)((u8*)b + usa_ofs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) * Cyclically increment the update sequence number
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) * (skipping 0 and -1, i.e. 0xffff).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) usn = le16_to_cpup(usa_pos) + 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) if (usn == 0xffff || !usn)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) usn = 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) le_usn = cpu_to_le16(usn);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) *usa_pos = le_usn;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) /* Position in data of first u16 that needs fixing up. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) data_pos = (le16*)b + NTFS_BLOCK_SIZE/sizeof(le16) - 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) /* Fixup all sectors. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) while (usa_count--) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) * Increment the position in the usa and save the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) * original data from the data buffer into the usa.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) *(++usa_pos) = *data_pos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) /* Apply fixup to data. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) *data_pos = le_usn;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) /* Increment position in data as well. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) data_pos += NTFS_BLOCK_SIZE/sizeof(le16);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) * post_write_mst_fixup - fast deprotect multi sector transfer protected data
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) * @b: pointer to the data to deprotect
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) * Perform the necessary post write multi sector transfer fixup, not checking
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) * for any errors, because we assume we have just used pre_write_mst_fixup(),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) * thus the data will be fine or we would never have gotten here.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) void post_write_mst_fixup(NTFS_RECORD *b)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) le16 *usa_pos, *data_pos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) u16 usa_ofs = le16_to_cpu(b->usa_ofs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) u16 usa_count = le16_to_cpu(b->usa_count) - 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) /* Position of usn in update sequence array. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) usa_pos = (le16*)b + usa_ofs/sizeof(le16);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) /* Position in protected data of first u16 that needs fixing up. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) data_pos = (le16*)b + NTFS_BLOCK_SIZE/sizeof(le16) - 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) /* Fixup all sectors. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) while (usa_count--) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) * Increment position in usa and restore original data from
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) * the usa into the data buffer.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) *data_pos = *(++usa_pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) /* Increment position in data as well. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) data_pos += NTFS_BLOCK_SIZE/sizeof(le16);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) }
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Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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