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part: Harden MBR detection code

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This commit is contained in:
mintsuki 2021-03-29 12:14:17 +02:00
parent 25bba4ecea
commit 0f0dddf75e
2 changed files with 82 additions and 1 deletions
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49
limine-install/limine-install.c
View File

@ -329,6 +329,55 @@ int main(int argc, char *argv[]) {
}
}
int mbr = 0;
if (gpt == 0) {
// Do all sanity checks on MBR
mbr = 1;
uint16_t hint = 0;
device_read(&hint, 218, sizeof(uint16_t));
if (hint != 0)
mbr = 0;
device_read(&hint, 444, sizeof(uint16_t));
if (hint != 0 && hint != 0x5a5a)
mbr = 0;
device_read(&hint, 510, sizeof(uint16_t));
if (hint != 0xaa55)
mbr = 0;
device_read(&hint, 446, sizeof(uint8_t));
if ((uint8_t)hint != 0x00 && (uint8_t)hint != 0x80)
mbr = 0;
device_read(&hint, 462, sizeof(uint8_t));
if ((uint8_t)hint != 0x00 && (uint8_t)hint != 0x80)
mbr = 0;
device_read(&hint, 478, sizeof(uint8_t));
if ((uint8_t)hint != 0x00 && (uint8_t)hint != 0x80)
mbr = 0;
device_read(&hint, 494, sizeof(uint8_t));
if ((uint8_t)hint != 0x00 && (uint8_t)hint != 0x80)
mbr = 0;
char hintc[64];
device_read(hintc, 4, 8);
if (memcmp(hintc, "_ECH_FS_", 8) == 0)
mbr = 0;
device_read(hintc, 54, 3);
if (memcmp(hintc, "FAT", 3) == 0)
mbr = 0;
device_read(&hint, 1080, sizeof(uint16_t));
if (hint == 0xef53)
mbr = 0;
}
if (gpt == 0 && mbr == 0) {
fprintf(stderr, "ERROR: Could not determine if the device has a valid partition table.\n");
fprintf(stderr, " Please ensure the device has a valid MBR or GPT.\n");
goto cleanup;
}
size_t stage2_size = bootloader_file_size - 512;
size_t stage2_sects = DIV_ROUNDUP(stage2_size, 512);

34
stage23/lib/part.s2.c
View File

@ -234,8 +234,40 @@ static int mbr_get_logical_part(struct volume *ret, struct volume *extended_part
static int mbr_get_part(struct volume *ret, struct volume *volume, int partition) {
// Check if actually valid mbr
uint16_t hint = 0;
volume_read(volume, &hint, 218, sizeof(uint16_t));
if (hint != 0)
return INVALID_TABLE;
volume_read(volume, &hint, 444, sizeof(uint16_t));
if (hint && hint != 0x5a5a)
if (hint != 0 && hint != 0x5a5a)
return INVALID_TABLE;
volume_read(volume, &hint, 510, sizeof(uint16_t));
if (hint != 0xaa55)
return INVALID_TABLE;
volume_read(volume, &hint, 446, sizeof(uint8_t));
if ((uint8_t)hint != 0x00 && (uint8_t)hint != 0x80)
return INVALID_TABLE;
volume_read(volume, &hint, 462, sizeof(uint8_t));
if ((uint8_t)hint != 0x00 && (uint8_t)hint != 0x80)
return INVALID_TABLE;
volume_read(volume, &hint, 478, sizeof(uint8_t));
if ((uint8_t)hint != 0x00 && (uint8_t)hint != 0x80)
return INVALID_TABLE;
volume_read(volume, &hint, 494, sizeof(uint8_t));
if ((uint8_t)hint != 0x00 && (uint8_t)hint != 0x80)
return INVALID_TABLE;
char hintc[64];
volume_read(volume, hintc, 4, 8);
if (memcmp(hintc, "_ECH_FS_", 8) == 0)
return INVALID_TABLE;
volume_read(volume, hintc, 54, 3);
if (memcmp(hintc, "FAT", 3) == 0)
return INVALID_TABLE;
volume_read(volume, &hint, 1080, sizeof(uint16_t));
if (hint == 0xef53)
return INVALID_TABLE;
struct mbr_entry entry;