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gpt: fix partition table indexing and validation

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Portions of the code attempted to handle the fact that GPT entries on
disk may be larger than the currently defined struct while others
assumed the data could be indexed by the struct size directly. This
never came up because no utility uses a size larger than 128 bytes but
for the sake of safety we need to do this by the spec.
This commit is contained in:
Michael Marineau 2016-08-24 16:14:20 -07:00
parent 87dfbf34c4
commit bf127238ee
4 changed files with 176 additions and 12 deletions
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6
grub-core/commands/gptprio.c
View file

@ -78,7 +78,7 @@ grub_find_next (const char *disk_name,
const grub_gpt_part_type_t *part_type,
char **part_name, char **part_guid)
{
struct grub_gpt_partentry *part_found = NULL;
struct grub_gpt_partentry *part, *part_found = NULL;
grub_device_t dev = NULL;
grub_gpt_t gpt = NULL;
grub_uint32_t i, part_index;
@ -95,10 +95,8 @@ grub_find_next (const char *disk_name,
if (grub_gpt_repair (dev->disk, gpt))
goto done;
for (i = 0; i < grub_le_to_cpu32 (gpt->primary.maxpart); i++)
for (i = 0; (part = grub_gpt_get_partentry (gpt, i)) != NULL; i++)
{
struct grub_gpt_partentry *part = &gpt->entries[i];
if (grub_memcmp (part_type, &part->type, sizeof (*part_type)) == 0)
{
unsigned int priority, tries_left, successful, old_priority = 0;

51
grub-core/lib/gpt.c
View file

@ -207,6 +207,13 @@ grub_gpt_pmbr_check (struct grub_msdos_partition_mbr *mbr)
return grub_error (GRUB_ERR_BAD_PART_TABLE, "invalid protective MBR");
}
static grub_uint64_t
grub_gpt_entries_size (struct grub_gpt_header *gpt)
{
return (grub_uint64_t) grub_le_to_cpu32 (gpt->maxpart) *
(grub_uint64_t) grub_le_to_cpu32 (gpt->partentry_size);
}
static grub_uint64_t
grub_gpt_entries_sectors (struct grub_gpt_header *gpt,
unsigned int log_sector_size)
@ -214,11 +221,16 @@ grub_gpt_entries_sectors (struct grub_gpt_header *gpt,
grub_uint64_t sector_bytes, entries_bytes;
sector_bytes = 1ULL << log_sector_size;
entries_bytes = (grub_uint64_t) grub_le_to_cpu32 (gpt->maxpart) *
(grub_uint64_t) grub_le_to_cpu32 (gpt->partentry_size);
entries_bytes = grub_gpt_entries_size (gpt);
return grub_divmod64(entries_bytes + sector_bytes - 1, sector_bytes, NULL);
}
static int
is_pow2 (grub_uint32_t n)
{
return (n & (n - 1)) == 0;
}
grub_err_t
grub_gpt_header_check (struct grub_gpt_header *gpt,
unsigned int log_sector_size)
@ -236,16 +248,23 @@ grub_gpt_header_check (struct grub_gpt_header *gpt,
if (gpt->crc32 != crc)
return grub_error (GRUB_ERR_BAD_PART_TABLE, "invalid GPT header crc32");
/* The header size must be between 92 and the sector size. */
/* The header size "must be greater than or equal to 92 and must be less
* than or equal to the logical block size." */
size = grub_le_to_cpu32 (gpt->headersize);
if (size < 92U || size > (1U << log_sector_size))
return grub_error (GRUB_ERR_BAD_PART_TABLE, "invalid GPT header size");
/* The partition entry size must be a multiple of 128. */
/* The partition entry size must be "a value of 128*(2^n) where n is an
* integer greater than or equal to zero (e.g., 128, 256, 512, etc.)." */
size = grub_le_to_cpu32 (gpt->partentry_size);
if (size < 128 || size % 128)
if (size < 128U || size % 128U || !is_pow2 (size / 128U))
return grub_error (GRUB_ERR_BAD_PART_TABLE, "invalid GPT entry size");
/* The minimum entries table size is specified in terms of bytes,
* regardless of how large the individual entry size is. */
if (grub_gpt_entries_size (gpt) < GRUB_GPT_DEFAULT_ENTRIES_SIZE)
return grub_error (GRUB_ERR_BAD_PART_TABLE, "invalid GPT entry table size");
/* And of course there better be some space for partitions! */
start = grub_le_to_cpu64 (gpt->start);
end = grub_le_to_cpu64 (gpt->end);
@ -411,7 +430,7 @@ static grub_err_t
grub_gpt_read_entries (grub_disk_t disk, grub_gpt_t gpt,
struct grub_gpt_header *header)
{
struct grub_gpt_partentry *entries = NULL;
void *entries = NULL;
grub_uint32_t count, size, crc;
grub_uint64_t sector;
grub_disk_addr_t addr;
@ -527,6 +546,26 @@ fail:
return NULL;
}
struct grub_gpt_partentry *
grub_gpt_get_partentry (grub_gpt_t gpt, grub_uint32_t n)
{
struct grub_gpt_header *header;
grub_size_t offset;
if (gpt->status & GRUB_GPT_PRIMARY_HEADER_VALID)
header = &gpt->primary;
else if (gpt->status & GRUB_GPT_BACKUP_HEADER_VALID)
header = &gpt->backup;
else
return NULL;
if (n >= grub_le_to_cpu32 (header->maxpart))
return NULL;
offset = (grub_size_t) grub_le_to_cpu32 (header->partentry_size) * n;
return (struct grub_gpt_partentry *) ((char *) gpt->entries + offset);
}
grub_err_t
grub_gpt_repair (grub_disk_t disk, grub_gpt_t gpt)
{

11
include/grub/gpt_partition.h
View file

@ -186,8 +186,10 @@ struct grub_gpt
struct grub_gpt_header primary;
struct grub_gpt_header backup;
/* Only need one entries table, on disk both copies are identical. */
struct grub_gpt_partentry *entries;
/* Only need one entries table, on disk both copies are identical.
* The on disk entry size may be larger than our partentry struct so
* the table cannot be indexed directly. */
void *entries;
grub_size_t entries_size;
/* Logarithm of sector size, in case GPT and disk driver disagree. */
@ -205,6 +207,11 @@ grub_gpt_sector_to_addr (grub_gpt_t gpt, grub_uint64_t sector)
/* Allocates and fills new grub_gpt structure, free with grub_gpt_free. */
grub_gpt_t grub_gpt_read (grub_disk_t disk);
/* Helper for indexing into the entries table.
* Returns NULL when the end of the table has been reached. */
struct grub_gpt_partentry * grub_gpt_get_partentry (grub_gpt_t gpt,
grub_uint32_t n);
/* Sync up primary and backup headers, recompute checksums. */
grub_err_t grub_gpt_repair (grub_disk_t disk, grub_gpt_t gpt);

120
tests/gpt_unit_test.c
View file

@ -40,6 +40,13 @@
/* from gnulib */
#include <verify.h>
/* Confirm that the GPT structures conform to the sizes in the spec:
* The header size "must be greater than or equal to 92 and must be less
* than or equal to the logical block size."
* The partition entry size must be "a value of 128*(2^n) where n is an
* integer greater than or equal to zero (e.g., 128, 256, 512, etc.)." */
verify (sizeof (struct grub_gpt_header) == 92);
verify (sizeof (struct grub_gpt_partentry) == 128);
/* GPT section sizes. */
#define HEADER_SIZE (sizeof (struct grub_gpt_header))
@ -537,6 +544,113 @@ repair_test (void)
close_disk (&data);
}
static void
iterate_partitions_test (void)
{
struct test_data data;
struct grub_gpt_partentry *p;
grub_gpt_t gpt;
grub_uint32_t n;
open_disk (&data);
gpt = read_disk (&data);
for (n = 0; (p = grub_gpt_get_partentry (gpt, n)) != NULL; n++)
grub_test_assert (memcmp (p, &example_entries[n], sizeof (*p)) == 0,
"unexpected partition %d data", n);
grub_test_assert (n == TABLE_ENTRIES, "unexpected partition limit: %d", n);
grub_gpt_free (gpt);
close_disk (&data);
}
static void
large_partitions_test (void)
{
struct test_data data;
struct grub_gpt_partentry *p;
grub_gpt_t gpt;
grub_uint32_t n;
open_disk (&data);
/* Double the entry size, cut the number of entries in half. */
data.raw->primary_header.maxpart =
data.raw->backup_header.maxpart =
grub_cpu_to_le32_compile_time (TABLE_ENTRIES/2);
data.raw->primary_header.partentry_size =
data.raw->backup_header.partentry_size =
grub_cpu_to_le32_compile_time (ENTRY_SIZE*2);
data.raw->primary_header.partentry_crc32 =
data.raw->backup_header.partentry_crc32 =
grub_cpu_to_le32_compile_time (0xf2c45af8);
data.raw->primary_header.crc32 = grub_cpu_to_le32_compile_time (0xde00cc8f);
data.raw->backup_header.crc32 = grub_cpu_to_le32_compile_time (0x6d72e284);
memset (&data.raw->primary_entries, 0,
sizeof (data.raw->primary_entries));
for (n = 0; n < TABLE_ENTRIES/2; n++)
memcpy (&data.raw->primary_entries[n*2], &example_entries[n],
sizeof (data.raw->primary_entries[0]));
memcpy (&data.raw->backup_entries, &data.raw->primary_entries,
sizeof (data.raw->backup_entries));
sync_disk(&data);
gpt = read_disk (&data);
for (n = 0; (p = grub_gpt_get_partentry (gpt, n)) != NULL; n++)
grub_test_assert (memcmp (p, &example_entries[n], sizeof (*p)) == 0,
"unexpected partition %d data", n);
grub_test_assert (n == TABLE_ENTRIES/2, "unexpected partition limit: %d", n);
grub_gpt_free (gpt);
/* Editing memory beyond the entry structure should still change the crc. */
data.raw->primary_entries[1].attrib = 0xff;
sync_disk(&data);
gpt = read_disk (&data);
grub_test_assert (gpt->status == (GRUB_GPT_PROTECTIVE_MBR |
GRUB_GPT_PRIMARY_HEADER_VALID |
GRUB_GPT_BACKUP_HEADER_VALID |
GRUB_GPT_BACKUP_ENTRIES_VALID),
"unexpected status: 0x%02x", gpt->status);
grub_gpt_free (gpt);
close_disk (&data);
}
static void
invalid_partsize_test (void)
{
struct grub_gpt_header header = {
.magic = GRUB_GPT_HEADER_MAGIC,
.version = GRUB_GPT_HEADER_VERSION,
.headersize = sizeof (struct grub_gpt_header),
.crc32 = grub_cpu_to_le32_compile_time (0x1ff2a054),
.header_lba = grub_cpu_to_le64_compile_time (PRIMARY_HEADER_SECTOR),
.alternate_lba = grub_cpu_to_le64_compile_time (BACKUP_HEADER_SECTOR),
.start = grub_cpu_to_le64_compile_time (DATA_START_SECTOR),
.end = grub_cpu_to_le64_compile_time (DATA_END_SECTOR),
.guid = GRUB_GPT_GUID_INIT(0x69c131ad, 0x67d6, 0x46c6,
0x93, 0xc4, 0x12, 0x4c, 0x75, 0x52, 0x56, 0xac),
.partitions = grub_cpu_to_le64_compile_time (PRIMARY_TABLE_SECTOR),
.maxpart = grub_cpu_to_le32_compile_time (TABLE_ENTRIES),
/* Triple the entry size, which is not valid. */
.partentry_size = grub_cpu_to_le32_compile_time (ENTRY_SIZE*3),
.partentry_crc32 = grub_cpu_to_le32_compile_time (0x074e052c),
};
grub_gpt_header_check(&header, GRUB_DISK_SECTOR_BITS);
grub_test_assert (grub_errno == GRUB_ERR_BAD_PART_TABLE,
"unexpected error: %s", grub_errmsg);
grub_test_assert (strcmp(grub_errmsg, "invalid GPT entry size") == 0,
"unexpected error: %s", grub_errmsg);
grub_errno = GRUB_ERR_NONE;
}
static void
search_part_label_test (void)
{
@ -657,6 +771,9 @@ grub_unit_test_init (void)
grub_test_register ("gpt_read_invalid_test", read_invalid_entries_test);
grub_test_register ("gpt_read_fallback_test", read_fallback_test);
grub_test_register ("gpt_repair_test", repair_test);
grub_test_register ("gpt_iterate_partitions_test", iterate_partitions_test);
grub_test_register ("gpt_large_partitions_test", large_partitions_test);
grub_test_register ("gpt_invalid_partsize_test", invalid_partsize_test);
grub_test_register ("gpt_search_part_label_test", search_part_label_test);
grub_test_register ("gpt_search_uuid_test", search_part_uuid_test);
grub_test_register ("gpt_search_disk_uuid_test", search_disk_uuid_test);
@ -671,6 +788,9 @@ grub_unit_test_fini (void)
grub_test_unregister ("gpt_read_invalid_test");
grub_test_unregister ("gpt_read_fallback_test");
grub_test_unregister ("gpt_repair_test");
grub_test_unregister ("gpt_iterate_partitions_test");
grub_test_unregister ("gpt_large_partitions_test");
grub_test_unregister ("gpt_invalid_partsize_test");
grub_test_unregister ("gpt_search_part_label_test");
grub_test_unregister ("gpt_search_part_uuid_test");
grub_test_unregister ("gpt_search_disk_uuid_test");