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New API calls iso_generate_gpt_guid() and +iso_write_opts_set_gpt_guid().

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This commit is contained in:
Thomas Schmitt
2016-08-12 18:18:47 +02:00
parent 2f134dcdcb
commit 866f647fad
8 changed files with 188 additions and 48 deletions
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111
libisofs/system_area.c
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@ -1476,8 +1476,12 @@ static void iso_write_gpt_entry(Ecma119Image *t, uint8_t *buf,
for (i = 0; i < 16; i++)
if (part_uuid[i])
break;
if (i == 16)
iso_random_uuid(t, part_uuid);
if (i == 16) {
if (!t->gpt_disk_guid_set)
iso_gpt_uuid(t, t->gpt_disk_guid);
t->gpt_disk_guid_set = 1;
iso_gpt_uuid(t, part_uuid);
}
memcpy(wpt, part_uuid, 16);
wpt += 16;
iso_lsb_to_buf(&wpt, start_lba & 0xffffffff, 4, 0);
@ -1538,9 +1542,8 @@ int iso_write_gpt_header_block(Ecma119Image *t, uint32_t img_blocks,
(uint32_t) ((back_lba - max_entries / 4 - 1) >> 32), 4, 1);
/* Disk GUID */
/* >>> Make adjustable */
if (!t->gpt_disk_guid_set)
iso_random_uuid(t, t->gpt_disk_guid);
iso_gpt_uuid(t, t->gpt_disk_guid);
t->gpt_disk_guid_set = 1;
memcpy(wpt, t->gpt_disk_guid, 16);
wpt += 16;
@ -2357,67 +2360,70 @@ uint32_t iso_crc32_gpt(unsigned char *data, int count, int flag)
return result ^ 0xffffffff;
}
void iso_random_uuid(Ecma119Image *t, uint8_t uuid[16])
void iso_mark_guid_version_4(uint8_t *u)
{
/* Mark as UUID version 4. RFC 4122 says u[6], but isohybrid swapping
effectively puts the 4 into u[7]. So i mark both. 4 bits wasted.
*/
u[6] = (u[6] & 0x0f) | 0x40;
u[7] = (u[7] & 0x0f) | 0x40;
/* Variant is "1 0 x" as described in RFC 4122.
*/
u[8] = (u[8] & 0x3f) | 0x80;
return;
}
void iso_generate_gpt_guid(uint8_t guid[16])
{
#ifdef Libisofs_with_uuid_generatE
uuid_t u;
uuid_generate(u);
swap_uuid((void *) u);
memcpy(guid, u, 16);
#else
uint8_t u[16];
uint8_t *u;
/* produced by uuid_generate() and byte-swapped to isohybrid.c habits */
static uint8_t uuid_template[16] = {
0xee, 0x29, 0x9d, 0xfc, 0x65, 0xcc, 0x7c, 0x40,
0x92, 0x61, 0x5b, 0xcd, 0x6f, 0xed, 0x08, 0x34
};
static uint8_t uuid_urandom[16];
uint32_t rnd, salt;
struct timeval tv;
pid_t pid;
static int counter = 0, use_urandom = 0;
int i, ret, fd;
#endif
#ifdef Libisofs_with_uuid_generatE
u = guid;
uuid_generate(u);
swap_uuid((void *) u);
memcpy(uuid, u, 16);
#else
/* First try /dev/urandom.
(Weakening the result by 8 bit saves a lot of pool entropy.)
/* First try /dev/urandom
*/
if ((counter & 0xff) == 0) {
fd = open("/dev/urandom", O_RDONLY | O_BINARY);
if (fd == -1)
goto fallback;
ret = read(fd, uuid_urandom, 16);
if (ret != 16) {
close(fd);
goto fallback;
}
/* Mark as UUID version 4 */
uuid_urandom[7] = (uuid_urandom[7] & 0x0f) | 0x40;
uuid_urandom[8] = (uuid_urandom[8] & 0x3f) | 0x80;
close(fd);
use_urandom = 1;
}
if (!use_urandom)
fd = open("/dev/urandom", O_RDONLY | O_BINARY);
if (fd == -1)
goto fallback;
memcpy(uuid, uuid_urandom, 16);
uuid[9] ^= counter & 0xff;
counter++;
ret = read(fd, u, 16);
if (ret != 16) {
close(fd);
goto fallback;
}
close(fd);
iso_mark_guid_version_4(u);
return;
fallback:;
pid = getpid();
salt = iso_crc32_gpt((unsigned char *) t, sizeof(Ecma119Image), 0) ^ pid;
salt = iso_crc32_gpt((unsigned char *) &guid, sizeof(uint8_t *), 0) ^ pid;
/* This relies on the uniqueness of the template and the rareness of
bootable ISO image production via libisofs. Estimated 53 bits of
bootable ISO image production via libisofs. Estimated 48 bits of
entropy should influence the production of a single day.
So first collisions are to be expected with about 100 million images
So first collisions are to be expected with about 16 million images
per day.
*/
memcpy(u, uuid_template, 16);
@ -2429,19 +2435,36 @@ fallback:;
u[6] = ((salt >> 8) ^ (pid >> 16)) & 0xff;
rnd = ((0xffffff & tv.tv_sec) << 8) |
(((tv.tv_usec >> 16) ^ (salt & 0xf0)) & 0xff);
u[9] ^= counter & 0xff;
for (i = 0; i < 4; i++)
u[10 + i] ^= (rnd >> (8 * i)) & 0xff;
u[14] ^= (tv.tv_usec >> 8) & 0xff;
u[15] ^= tv.tv_usec & 0xff;
counter++;
memcpy(uuid, u, 16);
iso_mark_guid_version_4(u);
return;
#endif /* ! Libisofs_with_uuid_generatE */
}
void iso_gpt_uuid(Ecma119Image *t, uint8_t uuid[16])
{
if (t->gpt_uuid_counter == 0)
iso_generate_gpt_guid(t->gpt_uuid_base);
memcpy(uuid, t->gpt_uuid_base, 16);
/* Previous implementation changed only byte 9. So i expand it by applying
the counter in little-endian style.
*/
uuid[9] ^= t->gpt_uuid_counter & 0xff;
uuid[10] ^= (t->gpt_uuid_counter >> 8) & 0xff;
uuid[11] ^= (t->gpt_uuid_counter >> 16) & 0xff;
uuid[12] ^= (t->gpt_uuid_counter >> 24) & 0xff;
t->gpt_uuid_counter++;
return;
}
int assess_appended_gpt(Ecma119Image *t, int flag)
{
static uint8_t basic_data_uuid[16] = {