summaryrefslogtreecommitdiffstats
path: root/grub-core/disk/luks.c
diff options
context:
space:
mode:
Diffstat (limited to 'grub-core/disk/luks.c')
-rw-r--r--grub-core/disk/luks.c329
1 files changed, 329 insertions, 0 deletions
diff --git a/grub-core/disk/luks.c b/grub-core/disk/luks.c
new file mode 100644
index 0000000..13103ea
--- /dev/null
+++ b/grub-core/disk/luks.c
@@ -0,0 +1,329 @@
+/*
+ * GRUB -- GRand Unified Bootloader
+ * Copyright (C) 2003,2007,2010,2011,2019 Free Software Foundation, Inc.
+ *
+ * GRUB is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GRUB is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/cryptodisk.h>
+#include <grub/types.h>
+#include <grub/misc.h>
+#include <grub/mm.h>
+#include <grub/dl.h>
+#include <grub/err.h>
+#include <grub/disk.h>
+#include <grub/crypto.h>
+#include <grub/partition.h>
+#include <grub/i18n.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+#define MAX_PASSPHRASE 256
+
+#define LUKS_KEY_ENABLED 0x00AC71F3
+
+/* On disk LUKS header */
+struct grub_luks_phdr
+{
+ grub_uint8_t magic[6];
+#define LUKS_MAGIC "LUKS\xBA\xBE"
+ grub_uint16_t version;
+ char cipherName[32];
+ char cipherMode[32];
+ char hashSpec[32];
+ grub_uint32_t payloadOffset;
+ grub_uint32_t keyBytes;
+ grub_uint8_t mkDigest[20];
+ grub_uint8_t mkDigestSalt[32];
+ grub_uint32_t mkDigestIterations;
+ char uuid[40];
+ struct
+ {
+ grub_uint32_t active;
+ grub_uint32_t passwordIterations;
+ grub_uint8_t passwordSalt[32];
+ grub_uint32_t keyMaterialOffset;
+ grub_uint32_t stripes;
+ } keyblock[8];
+} GRUB_PACKED;
+
+typedef struct grub_luks_phdr *grub_luks_phdr_t;
+
+gcry_err_code_t AF_merge (const gcry_md_spec_t * hash, grub_uint8_t * src,
+ grub_uint8_t * dst, grub_size_t blocksize,
+ grub_size_t blocknumbers);
+
+static grub_cryptodisk_t
+configure_ciphers (grub_disk_t disk, const char *check_uuid,
+ int check_boot)
+{
+ grub_cryptodisk_t newdev;
+ const char *iptr;
+ struct grub_luks_phdr header;
+ char *optr;
+ char uuid[sizeof (header.uuid) + 1];
+ char ciphername[sizeof (header.cipherName) + 1];
+ char ciphermode[sizeof (header.cipherMode) + 1];
+ char hashspec[sizeof (header.hashSpec) + 1];
+ grub_err_t err;
+
+ if (check_boot)
+ return NULL;
+
+ /* Read the LUKS header. */
+ err = grub_disk_read (disk, 0, 0, sizeof (header), &header);
+ if (err)
+ {
+ if (err == GRUB_ERR_OUT_OF_RANGE)
+ grub_errno = GRUB_ERR_NONE;
+ return NULL;
+ }
+
+ /* Look for LUKS magic sequence. */
+ if (grub_memcmp (header.magic, LUKS_MAGIC, sizeof (header.magic))
+ || grub_be_to_cpu16 (header.version) != 1)
+ return NULL;
+
+ grub_memset (uuid, 0, sizeof (uuid));
+ optr = uuid;
+ for (iptr = header.uuid; iptr < &header.uuid[ARRAY_SIZE (header.uuid)];
+ iptr++)
+ {
+ if (*iptr != '-')
+ *optr++ = *iptr;
+ }
+ *optr = 0;
+
+ if (check_uuid && grub_strcasecmp (check_uuid, uuid) != 0)
+ {
+ grub_dprintf ("luks", "%s != %s\n", uuid, check_uuid);
+ return NULL;
+ }
+
+ /* Make sure that strings are null terminated. */
+ grub_memcpy (ciphername, header.cipherName, sizeof (header.cipherName));
+ ciphername[sizeof (header.cipherName)] = 0;
+ grub_memcpy (ciphermode, header.cipherMode, sizeof (header.cipherMode));
+ ciphermode[sizeof (header.cipherMode)] = 0;
+ grub_memcpy (hashspec, header.hashSpec, sizeof (header.hashSpec));
+ hashspec[sizeof (header.hashSpec)] = 0;
+
+ newdev = grub_zalloc (sizeof (struct grub_cryptodisk));
+ if (!newdev)
+ return NULL;
+ newdev->offset_sectors = grub_be_to_cpu32 (header.payloadOffset);
+ newdev->source_disk = NULL;
+ newdev->log_sector_size = GRUB_LUKS1_LOG_SECTOR_SIZE;
+ newdev->total_sectors = grub_disk_native_sectors (disk) - newdev->offset_sectors;
+ grub_memcpy (newdev->uuid, uuid, sizeof (uuid));
+ newdev->modname = "luks";
+
+ /* Configure the hash used for the AF splitter and HMAC. */
+ newdev->hash = grub_crypto_lookup_md_by_name (hashspec);
+ if (!newdev->hash)
+ {
+ grub_free (newdev);
+ grub_error (GRUB_ERR_FILE_NOT_FOUND, "Couldn't load %s hash",
+ hashspec);
+ return NULL;
+ }
+
+ err = grub_cryptodisk_setcipher (newdev, ciphername, ciphermode);
+ if (err)
+ {
+ grub_free (newdev);
+ return NULL;
+ }
+
+ COMPILE_TIME_ASSERT (sizeof (newdev->uuid) >= sizeof (uuid));
+ return newdev;
+}
+
+static grub_err_t
+luks_recover_key (grub_disk_t source,
+ grub_cryptodisk_t dev)
+{
+ struct grub_luks_phdr header;
+ grub_size_t keysize;
+ grub_uint8_t *split_key = NULL;
+ char passphrase[MAX_PASSPHRASE] = "";
+ grub_uint8_t candidate_digest[sizeof (header.mkDigest)];
+ unsigned i;
+ grub_size_t length;
+ grub_err_t err;
+ grub_size_t max_stripes = 1;
+ char *tmp;
+
+ err = grub_disk_read (source, 0, 0, sizeof (header), &header);
+ if (err)
+ return err;
+
+ grub_puts_ (N_("Attempting to decrypt master key..."));
+ keysize = grub_be_to_cpu32 (header.keyBytes);
+ if (keysize > GRUB_CRYPTODISK_MAX_KEYLEN)
+ return grub_error (GRUB_ERR_BAD_FS, "key is too long");
+
+ for (i = 0; i < ARRAY_SIZE (header.keyblock); i++)
+ if (grub_be_to_cpu32 (header.keyblock[i].active) == LUKS_KEY_ENABLED
+ && grub_be_to_cpu32 (header.keyblock[i].stripes) > max_stripes)
+ max_stripes = grub_be_to_cpu32 (header.keyblock[i].stripes);
+
+ split_key = grub_calloc (keysize, max_stripes);
+ if (!split_key)
+ return grub_errno;
+
+ /* Get the passphrase from the user. */
+ tmp = NULL;
+ if (source->partition)
+ tmp = grub_partition_get_name (source->partition);
+ grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
+ source->partition ? "," : "", tmp ? : "",
+ dev->uuid);
+ grub_free (tmp);
+ if (!grub_password_get (passphrase, MAX_PASSPHRASE))
+ {
+ grub_free (split_key);
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, "Passphrase not supplied");
+ }
+
+ /* Try to recover master key from each active keyslot. */
+ for (i = 0; i < ARRAY_SIZE (header.keyblock); i++)
+ {
+ gcry_err_code_t gcry_err;
+ grub_uint8_t candidate_key[GRUB_CRYPTODISK_MAX_KEYLEN];
+ grub_uint8_t digest[GRUB_CRYPTODISK_MAX_KEYLEN];
+
+ /* Check if keyslot is enabled. */
+ if (grub_be_to_cpu32 (header.keyblock[i].active) != LUKS_KEY_ENABLED)
+ continue;
+
+ grub_dprintf ("luks", "Trying keyslot %d\n", i);
+
+ /* Calculate the PBKDF2 of the user supplied passphrase. */
+ gcry_err = grub_crypto_pbkdf2 (dev->hash, (grub_uint8_t *) passphrase,
+ grub_strlen (passphrase),
+ header.keyblock[i].passwordSalt,
+ sizeof (header.keyblock[i].passwordSalt),
+ grub_be_to_cpu32 (header.keyblock[i].
+ passwordIterations),
+ digest, keysize);
+
+ if (gcry_err)
+ {
+ grub_free (split_key);
+ return grub_crypto_gcry_error (gcry_err);
+ }
+
+ grub_dprintf ("luks", "PBKDF2 done\n");
+
+ gcry_err = grub_cryptodisk_setkey (dev, digest, keysize);
+ if (gcry_err)
+ {
+ grub_free (split_key);
+ return grub_crypto_gcry_error (gcry_err);
+ }
+
+ length = (keysize * grub_be_to_cpu32 (header.keyblock[i].stripes));
+
+ /* Read and decrypt the key material from the disk. */
+ err = grub_disk_read (source,
+ grub_be_to_cpu32 (header.keyblock
+ [i].keyMaterialOffset), 0,
+ length, split_key);
+ if (err)
+ {
+ grub_free (split_key);
+ return err;
+ }
+
+ gcry_err = grub_cryptodisk_decrypt (dev, split_key, length, 0,
+ GRUB_LUKS1_LOG_SECTOR_SIZE);
+ if (gcry_err)
+ {
+ grub_free (split_key);
+ return grub_crypto_gcry_error (gcry_err);
+ }
+
+ /* Merge the decrypted key material to get the candidate master key. */
+ gcry_err = AF_merge (dev->hash, split_key, candidate_key, keysize,
+ grub_be_to_cpu32 (header.keyblock[i].stripes));
+ if (gcry_err)
+ {
+ grub_free (split_key);
+ return grub_crypto_gcry_error (gcry_err);
+ }
+
+ grub_dprintf ("luks", "candidate key recovered\n");
+
+ /* Calculate the PBKDF2 of the candidate master key. */
+ gcry_err = grub_crypto_pbkdf2 (dev->hash, candidate_key,
+ grub_be_to_cpu32 (header.keyBytes),
+ header.mkDigestSalt,
+ sizeof (header.mkDigestSalt),
+ grub_be_to_cpu32
+ (header.mkDigestIterations),
+ candidate_digest,
+ sizeof (candidate_digest));
+ if (gcry_err)
+ {
+ grub_free (split_key);
+ return grub_crypto_gcry_error (gcry_err);
+ }
+
+ /* Compare the calculated PBKDF2 to the digest stored
+ in the header to see if it's correct. */
+ if (grub_memcmp (candidate_digest, header.mkDigest,
+ sizeof (header.mkDigest)) != 0)
+ {
+ grub_dprintf ("luks", "bad digest\n");
+ continue;
+ }
+
+ /* TRANSLATORS: It's a cryptographic key slot: one element of an array
+ where each element is either empty or holds a key. */
+ grub_printf_ (N_("Slot %d opened\n"), i);
+
+ /* Set the master key. */
+ gcry_err = grub_cryptodisk_setkey (dev, candidate_key, keysize);
+ if (gcry_err)
+ {
+ grub_free (split_key);
+ return grub_crypto_gcry_error (gcry_err);
+ }
+
+ grub_free (split_key);
+
+ return GRUB_ERR_NONE;
+ }
+
+ grub_free (split_key);
+ return GRUB_ACCESS_DENIED;
+}
+
+struct grub_cryptodisk_dev luks_crypto = {
+ .scan = configure_ciphers,
+ .recover_key = luks_recover_key
+};
+
+GRUB_MOD_INIT (luks)
+{
+ COMPILE_TIME_ASSERT (sizeof (((struct grub_luks_phdr *) 0)->uuid)
+ < GRUB_CRYPTODISK_MAX_UUID_LENGTH);
+ grub_cryptodisk_dev_register (&luks_crypto);
+}
+
+GRUB_MOD_FINI (luks)
+{
+ grub_cryptodisk_dev_unregister (&luks_crypto);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-09 08:47:19 +0000