Verifying checksum tags of superblock and tree if available and enabled.
New API call iso_md5_match().
This commit is contained in:
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868005ed0e
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8b800094af
@ -2278,15 +2278,83 @@ int read_el_torito_boot_catalog(_ImageFsData *data, uint32_t block)
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return ISO_SUCCESS;
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}
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/*
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@return 1= ok, checked, go on with loading
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2= no checksum tags found, go on with loading
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<0= libisofs error
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especially ISO_SB_TREE_CORRUPTED
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*/
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static
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int iso_src_check_sb_tree(IsoDataSource *src, uint32_t start_lba, int flag)
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{
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int tag_type, ret;
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char block[2048], md5[16];
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int desired = (1 << 2);
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void *ctx = NULL;
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uint32_t next_tag = 0, i;
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/* >>>> */;
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ret = iso_md5_start(&ctx);
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if (ret < 0)
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goto ex;
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if (start_lba == 0)
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desired |= (1 << 4);
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for (i = 0; i < 32; i++) {
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ret = src->read_block(src, start_lba + i, (uint8_t *) block);
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if (ret < 0)
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goto ex;
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ret = 0;
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if (i >= 16)
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ret = iso_util_eval_md5_tag(block, desired, start_lba + i,
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ctx, start_lba, &tag_type, &next_tag, 0);
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iso_md5_compute(ctx, block, 2048);
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if (ret == ISO_MD5_AREA_CORRUPTED || ret == ISO_MD5_TAG_MISMATCH)
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ret = ISO_SB_TREE_CORRUPTED;
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if (ret < 0)
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goto ex;
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if (ret == 1)
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break;
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}
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if (i >= 32) {
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ret = 2;
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goto ex;
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}
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if (tag_type == 4) {
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/* Relocated Superblock: restart checking at real session start */
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if (next_tag < 32) {
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/* Non plausible session_start address */
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iso_msg_submit(-1, ret, 0, NULL);
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ret = ISO_SB_TREE_CORRUPTED;
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goto ex;
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}
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/* Check real session */
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ret = iso_src_check_sb_tree(src, next_tag, 0);
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goto ex;
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}
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return 2;
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/* Go on with tree */
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for (i++; start_lba + i <= next_tag; i++) {
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ret = src->read_block(src, start_lba + i, (uint8_t *) block);
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if (ret < 0)
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goto ex;
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if (start_lba + i < next_tag)
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iso_md5_compute(ctx, block, 2048);
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}
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ret = iso_util_eval_md5_tag(block, (1 << 3), start_lba + i - 1,
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ctx, start_lba, &tag_type, &next_tag, 0);
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if (ret == ISO_MD5_AREA_CORRUPTED || ret == ISO_MD5_TAG_MISMATCH)
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ret = ISO_SB_TREE_CORRUPTED;
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if (ret < 0)
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goto ex;
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ret = 1;
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ex:
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if (ctx != NULL)
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iso_md5_end(&ctx, md5);
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return ret;
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}
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int iso_image_filesystem_new(IsoDataSource *src, struct iso_read_opts *opts,
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int msgid, IsoImageFilesystem **fs)
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{
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@ -2355,12 +2423,13 @@ int iso_image_filesystem_new(IsoDataSource *src, struct iso_read_opts *opts,
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if (data->md5_load) {
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/* >>> From opts->block on : check for superblock and tree tags */;
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/* From opts->block on : check for superblock and tree tags */;
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ret = iso_src_check_sb_tree(src, opts->block, 0);
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if (ret <= 0) {
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/* >>> refuse to load, hint towards loading without MD5 check */;
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goto fs_cleanup;
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}
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}
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@ -5169,6 +5169,20 @@ int iso_md5_clone(void *old_md5_context, void **new_md5_context);
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*/
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int iso_md5_end(void **md5_context, char result[16]);
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/**
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* Inquire whether two MD5 checksums match. (This is trivial but such a call
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* is convenient and completes the interface.)
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* @param first_md5
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* A MD5 byte string as returned by iso_md5_end()
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* @param second_md5
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* A MD5 byte string as returned by iso_md5_end()
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* @return
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* 1= match , 0= mismatch
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*
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* @since 0.6.22
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*/
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int iso_md5_match(char first_md5[16], char second_md5[16]);
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/************ Error codes and return values for libisofs ********************/
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@ -5426,11 +5440,43 @@ int iso_md5_end(void **md5_context, char result[16]);
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#define ISO_ZLIB_EARLY_EOF 0xE830FEA1
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/**
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* Checksum area appears damaged and not trustworthy for verifications.
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* (WARNING,HIGH, -352)
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* Checksum area or checksum tag appear corrupted (WARNING,HIGH, -352)
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* @since 0.6.22
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*/
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#define ISO_MD5_AREA_CORRUPTED 0xD030FEA0
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#define ISO_MD5_AREA_CORRUPTED 0xD030FEA0
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/**
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* Checksum mismatch between checksum tag and data blocks
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* (FAILURE, HIGH, -353)
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* @since 0.6.22
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*/
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#define ISO_MD5_TAG_MISMATCH 0xE830FE9F
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/**
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* Checksum mismatch in System Area, Volume Descriptors, or directory tree.
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* (FAILURE, HIGH, -354)
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* @since 0.6.22
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*/
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#define ISO_SB_TREE_CORRUPTED 0xE830FE9E
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/**
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* Unexpected checksum tag type encountered. (WARNING, HIGH, -355)
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* @since 0.6.22
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*/
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#define ISO_MD5_TAG_UNEXPECTED 0xD030FE9D
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/**
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* Misplaced checksum tag encountered. (WARNING, HIGH, -356)
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* @since 0.6.22
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*/
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#define ISO_MD5_TAG_MISPLACED 0xD030FE9C
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/**
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* Checksum tag with unexpected address range encountered.
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* (WARNING, HIGH, -357)
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* @since 0.6.22
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*/
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#define ISO_MD5_TAG_OTHER_RANGE 0xD030FE9B
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/* ! PLACE NEW ERROR CODES HERE ! */
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@ -16,6 +16,7 @@
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#include "messages.h"
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#include "ecma119.h"
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#include "image.h"
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#include "util.h"
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#include "md5.h"
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@ -386,6 +387,18 @@ int iso_md5_end(void **md5_context, char result[16])
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}
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/* API */
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int iso_md5_match(char first_md5[16], char second_md5[16])
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{
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int i;
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for (i= 0; i < 16; i++)
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if (first_md5[i] != second_md5[i])
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return 0;
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return 1;
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}
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/* ----------------------------------------------------------------------- */
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@ -667,15 +680,10 @@ int iso_md5_write_tag(Ecma119Image *t, int flag)
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#ifdef Libisofs_with_checksumS
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int res, mode, l, i, wres;
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int res, mode, l, i, wres, tag_id_len;
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void *ctx = NULL;
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char md5[16], tag_block[2048];
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char md5[16], tag_block[2048], *tag_id;
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uint32_t size = 0, pos = 0, start;
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static char *tag_ids[] = {"",
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"libisofs_checksum_tag_v1",
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"libisofs_sb_checksum_tag_v1",
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"libisofs_tree_checksum_tag_v1",
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"libisofs_rlsb32_checksum_tag_v1"};
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start = t->checksum_range_start;
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memset(tag_block, 0, 2048);
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@ -702,9 +710,10 @@ int iso_md5_write_tag(Ecma119Image *t, int flag)
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return ISO_WRONG_ARG_VALUE;
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}
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if (res > 0) {
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iso_util_tag_magic(mode, &tag_id, &tag_id_len, 0);
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sprintf(tag_block,
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"%s pos=%u range_start=%u range_size=%u",
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tag_ids[mode], pos, start, size);
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tag_id, pos, start, size);
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l = strlen(tag_block);
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if (mode == 2) {
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@ -261,7 +261,17 @@ const char *iso_error_to_msg(int errcode)
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case ISO_ZLIB_EARLY_EOF:
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return "Premature EOF of zlib input stream";
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case ISO_MD5_AREA_CORRUPTED:
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return "Checksum area appears damaged and not trustworthy for verifications";
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return "Checksum area or checksum tag appear corrupted";
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case ISO_MD5_TAG_MISMATCH:
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return "Checksum mismatch between checksum tag and data blocks";
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case ISO_SB_TREE_CORRUPTED:
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return "Checksum mismatch in System Area, Volume Descriptors, or directory tree";
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case ISO_MD5_TAG_UNEXPECTED:
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return "Unexpected checksum tag type encountered";
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case ISO_MD5_TAG_MISPLACED:
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return "Misplaced checksum tag type encountered";
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case ISO_MD5_TAG_OTHER_RANGE:
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return "Checksum tag with unexpected address range encountered";
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default:
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return "Unknown error";
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}
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@ -9,6 +9,7 @@
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#include "util.h"
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#include "libisofs.h"
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#include "messages.h"
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#include "../version.h"
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#include <stdlib.h>
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@ -1563,18 +1564,33 @@ int iso_util_hex_to_bin(char *hex, char *bin, int bin_size, int *bin_count,
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}
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int iso_util_tag_magic(int tag_type, char **tag_magic, int *len, int flag)
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{
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static char *magic[] = {"",
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"libisofs_checksum_tag_v1",
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"libisofs_sb_checksum_tag_v1",
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"libisofs_tree_checksum_tag_v1",
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"libisofs_rlsb32_checksum_tag_v1"};
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static int magic_len[]= {0, 24, 27, 29, 31};
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static int magic_max = 4;
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*tag_magic = NULL;
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*len = 0;
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if (tag_type < 0 || tag_type > magic_max)
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return ISO_WRONG_ARG_VALUE;
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*tag_magic = magic[tag_type];
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*len = magic_len[tag_type];
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return magic_max;
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}
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int iso_util_decode_md5_tag(char data[2048], int *tag_type, uint32_t *pos,
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uint32_t *range_start, uint32_t *range_size,
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uint32_t *next_tag, char md5[16], int flag)
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{
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static char *tag_magic[] = {"",
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"libisofs_checksum_tag_v1",
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"libisofs_sb_checksum_tag_v1",
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"libisofs_tree_checksum_tag_v1",
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"libisofs_rlsb32_checksum_tag_v1"};
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static int magic_len[]= {0, 24, 27, 29, 31};
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int ret, bin_count, i, mode, magic_first = 1, magic_last = 4;
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char *cpt, self_md5[16], tag_md5[16];
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int magic_len = 0;
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char *cpt, self_md5[16], tag_md5[16], *tag_magic;
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void *ctx = NULL;
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*next_tag = 0;
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@ -1583,13 +1599,15 @@ int iso_util_decode_md5_tag(char data[2048], int *tag_type, uint32_t *pos,
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return ISO_WRONG_ARG_VALUE;
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if (mode > 0)
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magic_first = magic_last = mode;
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for (i = magic_first; i <= magic_last; i++)
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if (strncmp(data, tag_magic[i], magic_len[i]) == 0)
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for (i = magic_first; i <= magic_last; i++) {
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iso_util_tag_magic(i, &tag_magic, &magic_len, 0);
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if (strncmp(data, tag_magic, magic_len) == 0)
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break;
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}
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if (i > magic_last )
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return 0;
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*tag_type = i;
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cpt = data + magic_len[*tag_type] + 1;
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cpt = data + magic_len + 1;
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if (strncmp(cpt, "pos=", 4) != 0)
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return 0;
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cpt+= 4;
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@ -1650,3 +1668,51 @@ int iso_util_decode_md5_tag(char data[2048], int *tag_type, uint32_t *pos,
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return(1);
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}
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int iso_util_eval_md5_tag(char *block, int desired, uint32_t lba,
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void *ctx, uint32_t ctx_start_lba,
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int *tag_type, uint32_t *next_tag, int flag)
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{
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int decode_ret, ret;
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char md5[16], cloned_md5[16];
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uint32_t pos, range_start, range_size;
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void *cloned_ctx = NULL;
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*tag_type = 0;
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decode_ret = iso_util_decode_md5_tag(block, tag_type, &pos,
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&range_start, &range_size, next_tag, md5, 0);
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if (decode_ret != 1 && decode_ret != ISO_MD5_AREA_CORRUPTED)
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return 0;
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if (*tag_type > 30)
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goto unexpected_type;
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if (decode_ret == ISO_MD5_AREA_CORRUPTED) {
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ret = decode_ret;
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goto ex;
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} else if (!((1 << *tag_type) & desired)) {
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unexpected_type:;
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iso_msg_submit(-1, ISO_MD5_TAG_UNEXPECTED, 0, NULL);
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ret = 0;
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goto ex;
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} else if(pos != lba) {
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ret = ISO_MD5_TAG_MISPLACED;
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goto ex;
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} else if(range_start != ctx_start_lba) {
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ret = ISO_MD5_TAG_MISPLACED;
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}
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ret = iso_md5_clone(ctx, &cloned_ctx);
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if (ret < 0)
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goto ex;
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iso_md5_end(&cloned_ctx, cloned_md5);
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if (! iso_md5_match(cloned_md5, md5)) {
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ret = ISO_MD5_TAG_MISMATCH;
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goto ex;
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}
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ret = 1;
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ex:;
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if (ret < 0)
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iso_msg_submit(-1, ret, 0, NULL);
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return ret;
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}
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@ -458,4 +458,28 @@ int iso_util_encode_len_bytes(uint32_t data, char *buffer, int data_len,
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int iso_util_decode_len_bytes(uint32_t *data, char *buffer, int *data_len,
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int buffer_len, int flag);
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/* Evaluate a data block whether it is a libisofs session checksum tag of
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desired type and eventually use it to verify the MD5 checksum computed
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so far.
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@param block The data block to be evaluated
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@param desired Bit map which tells what tag types are expected
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(0 to 30)
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@param lba The address from where block was read
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@param ctx The checksum context computed so far
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@param ctx_start_lba The block address where checksum computing started
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@param tag_type Returns the tag type (0 means invalid tag type)
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@param flag Bitfield for control purposes, unused yet, submit 0
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@return 1= tag is desired and matches
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0= not a recognizable tag or a undesired tag
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<0 is error or mismatch
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*/
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int iso_util_eval_md5_tag(char *block, int desired, uint32_t lba,
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void *ctx, uint32_t ctx_start_lba,
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int *tag_type, uint32_t *next_tag, int flag);
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int iso_util_tag_magic(int tag_type, char **tag_magic, int *len, int flag);
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#endif /*LIBISO_UTIL_H_*/
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Block a user