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Made isohybrid MBR id reproducible if vol_modification_time or vol_uuid are set

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This commit is contained in:
Thomas Schmitt 2016-08-05 20:59:17 +02:00
parent 188e36178b
commit 6321ed4d97
1 changed files with 21 additions and 4 deletions
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25
libisofs/make_isohybrid_mbr.c
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@ -604,8 +604,28 @@ static int gpt_images_as_mbr_partitions(Ecma119Image *t, char *wpt,
}
/* For generating a weak random number */
static uint32_t iso_make_mbr_id(Ecma119Image *t, int flag)
{
uint32_t id;
struct timeval tv;
if(t->opts->vol_uuid[0]) {
id = iso_crc32_gpt((unsigned char *) t->opts->vol_uuid, 16, 0);
} else if(t->opts->vol_modification_time > 0) {
id = iso_crc32_gpt((unsigned char *) &(t->opts->vol_modification_time),
sizeof(time_t), 0);
} else {
gettimeofday(&tv, NULL);
id = 0xffffffff & (tv.tv_sec ^ (tv.tv_usec * 2000));
}
return id;
}
/*
* @param flag bit0= make own random MBR Id from current time
* >>> or from overridden modification time
* bit1= create protective MBR as of UEFI/GPT specs
*/
int make_isolinux_mbr(uint32_t *img_blocks, Ecma119Image *t,
@ -618,8 +638,6 @@ int make_isolinux_mbr(uint32_t *img_blocks, Ecma119Image *t,
uint32_t boot_lba;
int head_count, sector_count, ret;
int gpt_count = 0, gpt_idx[128], apm_count = 0, gpt_cursor, i;
/* For generating a weak random number */
struct timeval tv;
if (t->bootsrc[0] == NULL)
return iso_msg_submit(t->image->id, ISO_BOOT_IMAGE_NOT_VALID, 0,
@ -668,8 +686,7 @@ int make_isolinux_mbr(uint32_t *img_blocks, Ecma119Image *t,
(here some 32-bit random value with no crypto strength)
*/
if (flag & 1) {
gettimeofday(&tv, NULL);
id = 0xffffffff & (tv.tv_sec ^ (tv.tv_usec * 2000));
id = iso_make_mbr_id(t, 0);
lsb_to_buf(&wpt, id, 32, 0);
} else {
wpt+= 4;