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blkid: Add support for LUKS2 and new LABEL attributes. 

This patch adds support for detection of a LUKS2 superblock.

LUKS2 is new version of Linux Unified Key Setup for encrypted
block devices.

LUKS2 contains a binary header and then JSON area for metadata.
Blkid should only parse the binary part, including newly available
optional LABEL and SUBSYSTEM fields.

LABEL is similar to filesystem label. The SUBSYSTEM field is
in principle, just a second label and can be used for specific udev rules
(for example if you have some 3rd party system that activates
volumes automatically, you can mark devices using this attribute).
Both labels are optional.

The magic string and UUID location are intentionally on the same offset
as LUKS v1, so even unpatched blkid now recognizes LUKS2.

Anyway, the code should not parse other versions of the header, so we now
explicitly check for header version and support only version 1 and 2.

Signed-off-by: Milan Broz <gmazyland@gmail.com>
This commit is contained in:
Milan Broz 2017-10-23 16:26:51 +02:00 committed by Karel Zak
parent c71665adb5
commit 573538bfba
1 changed files with 38 additions and 4 deletions
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42
libblkid/src/superblocks/luks.c
View File

@ -24,6 +24,10 @@
#define LUKS_SALTSIZE 32
#define LUKS_MAGIC_L 6
#define UUID_STRING_L 40
#define LUKS2_LABEL_L 48
#define LUKS2_SALT_L 64
#define LUKS2_CHECKSUM_ALG_L 32
#define LUKS2_CHECKSUM_L 64
struct luks_phdr {
uint8_t magic[LUKS_MAGIC_L];
@ -39,17 +43,47 @@ struct luks_phdr {
uint8_t uuid[UUID_STRING_L];
} __attribute__((packed));
struct luks2_phdr {
char magic[LUKS_MAGIC_L];
uint16_t version;
uint64_t hdr_size; /* in bytes, including JSON area */
uint64_t seqid; /* increased on every update */
char label[LUKS2_LABEL_L];
char checksum_alg[LUKS2_CHECKSUM_ALG_L];
uint8_t salt[LUKS2_SALT_L]; /* unique for every header/offset */
char uuid[UUID_STRING_L];
char subsystem[LUKS2_LABEL_L]; /* owner subsystem label */
uint64_t hdr_offset; /* offset from device start in bytes */
char _padding[184];
uint8_t csum[LUKS2_CHECKSUM_L];
/* Padding to 4k, then JSON area */
} __attribute__ ((packed));
static int probe_luks(blkid_probe pr, const struct blkid_idmag *mag)
{
struct luks_phdr *header;
struct luks_phdr *header_v1;
struct luks2_phdr *header;
int version;
header = blkid_probe_get_sb(pr, mag, struct luks_phdr);
header = blkid_probe_get_sb(pr, mag, struct luks2_phdr);
if (header == NULL)
return errno ? -errno : 1;
blkid_probe_strncpy_uuid(pr, (unsigned char *) header->uuid,
sizeof(header->uuid));
version = be16_to_cpu(header->version);
blkid_probe_sprintf_version(pr, "%u", be16_to_cpu(header->version));
if (version == 1) {
header_v1 = (struct luks_phdr *)header;
blkid_probe_strncpy_uuid(pr,
(unsigned char *) header_v1->uuid, UUID_STRING_L);
} else if (version == 2) {
blkid_probe_strncpy_uuid(pr,
(unsigned char *) header->uuid, UUID_STRING_L);
blkid_probe_set_label(pr,
(unsigned char *) header->label, LUKS2_LABEL_L);
blkid_probe_set_id_label(pr, "SUBSYSTEM",
(unsigned char *) header->subsystem, LUKS2_LABEL_L);
}
return 0;
}