File 0004-cryptodisk-Support-key-protectors.patch of Package grub2
From 9888bf40d960339a59dc18fb6e1df5f65b4668e3 Mon Sep 17 00:00:00 2001
From: Hernan Gatta <hegatta@linux.microsoft.com>
Date: Tue, 1 Feb 2022 05:02:56 -0800
Subject: [PATCH 13/14] cryptodisk: Support key protectors
Add a new parameter to cryptomount to support the key protectors framework: -k.
The parameter is used to automatically retrieve a key from specified key
protectors. The parameter may be repeated to specify any number of key
protectors. These are tried in order until one provides a usable key for any
given disk.
Signed-off-by: <Hernan Gatta hegatta@linux.microsoft.com>
---
Makefile.util.def | 1 +
grub-core/disk/cryptodisk.c | 166 +++++++++++++++++++++++++++++-------
include/grub/cryptodisk.h | 14 +++
3 files changed, 151 insertions(+), 30 deletions(-)
--- a/Makefile.util.def
+++ b/Makefile.util.def
@@ -35,6 +35,7 @@
common = grub-core/kern/list.c;
common = grub-core/kern/misc.c;
common = grub-core/kern/partition.c;
+ common = grub-core/kern/protectors.c;
common = grub-core/lib/crypto.c;
common = grub-core/lib/json/json.c;
common = grub-core/disk/luks.c;
--- a/grub-core/disk/cryptodisk.c
+++ b/grub-core/disk/cryptodisk.c
@@ -26,6 +26,7 @@
#include <grub/file.h>
#include <grub/procfs.h>
#include <grub/partition.h>
+#include <grub/protector.h>
#ifdef GRUB_UTIL
#include <grub/emu/hostdisk.h>
@@ -44,7 +45,8 @@
OPTION_KEYFILE,
OPTION_KEYFILE_OFFSET,
OPTION_KEYFILE_SIZE,
- OPTION_HEADER
+ OPTION_HEADER,
+ OPTION_PROTECTOR
};
static const struct grub_arg_option options[] =
@@ -58,6 +60,8 @@
{"keyfile-offset", 'O', 0, N_("Key file offset (bytes)"), 0, ARG_TYPE_INT},
{"keyfile-size", 'S', 0, N_("Key file data size (bytes)"), 0, ARG_TYPE_INT},
{"header", 'H', 0, N_("Read header from file"), 0, ARG_TYPE_STRING},
+ {"protector", 'P', GRUB_ARG_OPTION_REPEATABLE,
+ N_("Unlock volume(s) using key protector(s)."), 0, ARG_TYPE_STRING},
{0, 0, 0, 0, 0, 0}
};
@@ -1061,6 +1065,7 @@
grub_err_t ret = GRUB_ERR_NONE;
grub_cryptodisk_t dev;
grub_cryptodisk_dev_t cr;
+ int i;
struct cryptodisk_read_hook_ctx read_hook_data = {0};
int askpass = 0;
char *part = NULL;
@@ -1113,41 +1118,112 @@
goto error_no_close;
if (!dev)
continue;
+ break;
+ }
- if (!cargs->key_len)
- {
- /* Get the passphrase from the user, if no key data. */
- askpass = 1;
- part = grub_partition_get_name (source->partition);
- grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
- source->partition != NULL ? "," : "",
- part != NULL ? part : N_("UNKNOWN"),
- dev->uuid);
- grub_free (part);
-
- cargs->key_data = grub_malloc (GRUB_CRYPTODISK_MAX_PASSPHRASE);
- if (cargs->key_data == NULL)
- goto error_no_close;
+ if (dev == NULL)
+ {
+ grub_error (GRUB_ERR_BAD_MODULE,
+ "no cryptodisk module can handle this device");
+ goto error_no_close;
+ }
- if (!grub_password_get ((char *) cargs->key_data, GRUB_CRYPTODISK_MAX_PASSPHRASE))
- {
- grub_error (GRUB_ERR_BAD_ARGUMENT, "passphrase not supplied");
- goto error;
- }
- cargs->key_len = grub_strlen ((char *) cargs->key_data);
- }
+ if (cargs->protectors)
+ {
+ for (i = 0; cargs->protectors[i]; i++)
+ {
+ if (cargs->key_cache[i].invalid)
+ continue;
- ret = cr->recover_key (source, dev, cargs);
- if (ret != GRUB_ERR_NONE)
- goto error;
+ if (cargs->key_cache[i].key == NULL)
+ {
+ ret = grub_key_protector_recover_key (cargs->protectors[i],
+ &cargs->key_cache[i].key,
+ &cargs->key_cache[i].key_len);
+ if (ret != GRUB_ERR_NONE)
+ {
+ if (grub_errno)
+ {
+ grub_print_error ();
+ grub_errno = GRUB_ERR_NONE;
+ }
+
+ grub_dprintf ("cryptodisk",
+ "failed to recover a key from key protector "
+ "%s, will not try it again for any other "
+ "disks, if any, during this invocation of "
+ "cryptomount\n",
+ cargs->protectors[i]);
+
+ cargs->key_cache[i].invalid = 1;
+ continue;
+ }
+ }
+
+ cargs->key_data = cargs->key_cache[i].key;
+ cargs->key_len = cargs->key_cache[i].key_len;
+
+ ret = cr->recover_key (source, dev, cargs);
+ if (ret != GRUB_ERR_NONE)
+ {
+ part = grub_partition_get_name (source->partition);
+ grub_dprintf ("cryptodisk",
+ "recovered a key from key protector %s but it "
+ "failed to unlock %s%s%s (%s)\n",
+ cargs->protectors[i], source->name,
+ source->partition != NULL ? "," : "",
+ part != NULL ? part : N_("UNKNOWN"), dev->uuid);
+ grub_free (part);
+ continue;
+ }
+ else
+ {
+ ret = grub_cryptodisk_insert (dev, name, source);
+ if (ret != GRUB_ERR_NONE)
+ goto error;
+ goto cleanup;
+ }
+ }
- ret = grub_cryptodisk_insert (dev, name, source);
- if (ret != GRUB_ERR_NONE)
+ part = grub_partition_get_name (source->partition);
+ grub_error (GRUB_ERR_ACCESS_DENIED,
+ N_("no key protector provided a usable key for %s%s%s (%s)"),
+ source->name, source->partition != NULL ? "," : "",
+ part != NULL ? part : N_("UNKNOWN"), dev->uuid);
+ grub_free (part);
goto error;
+ }
+
+ if (!cargs->key_len)
+ {
+ /* Get the passphrase from the user, if no key data. */
+ askpass = 1;
+ part = grub_partition_get_name (source->partition);
+ grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
+ source->partition != NULL ? "," : "",
+ part != NULL ? part : N_("UNKNOWN"), dev->uuid);
+ grub_free (part);
+
+ cargs->key_data = grub_malloc (GRUB_CRYPTODISK_MAX_PASSPHRASE);
+ if (cargs->key_data == NULL)
+ goto error;
+
+ if (!grub_password_get ((char *) cargs->key_data, GRUB_CRYPTODISK_MAX_PASSPHRASE))
+ {
+ grub_error (GRUB_ERR_BAD_ARGUMENT, "passphrase not supplied");
+ goto error;
+ }
+ cargs->key_len = grub_strlen ((char *) cargs->key_data);
+ }
+
+ ret = cr->recover_key (source, dev, cargs);
+ if (ret != GRUB_ERR_NONE)
+ goto error;
+
+ ret = grub_cryptodisk_insert (dev, name, source);
+ if (ret != GRUB_ERR_NONE)
+ goto error;
- goto cleanup;
- }
- grub_error (GRUB_ERR_BAD_MODULE, "no cryptodisk module can handle this device");
goto cleanup;
error:
@@ -1258,6 +1334,20 @@
return ret;
}
+static void
+grub_cryptodisk_clear_key_cache (struct grub_cryptomount_args *cargs)
+{
+ int i;
+
+ if (cargs->key_cache == NULL || cargs->protectors == NULL)
+ return;
+
+ for (i = 0; cargs->protectors[i]; i++)
+ grub_free (cargs->key_cache[i].key);
+
+ grub_free (cargs->key_cache);
+}
+
static grub_err_t
grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int argc, char **args)
{
@@ -1270,6 +1360,10 @@
if (grub_cryptodisk_list == NULL)
return grub_error (GRUB_ERR_BAD_MODULE, "no cryptodisk modules loaded");
+ if (state[OPTION_PASSWORD].set && state[OPTION_PROTECTOR].set) /* password and key protector */
+ return grub_error (GRUB_ERR_BAD_ARGUMENT,
+ "a password and a key protector cannot both be set");
+
if (state[OPTION_PASSWORD].set) /* password */
{
cargs.key_data = (grub_uint8_t *) state[OPTION_PASSWORD].arg;
@@ -1362,6 +1456,15 @@
return grub_errno;
}
+ if (state[OPTION_PROTECTOR].set) /* key protector(s) */
+ {
+ cargs.key_cache = grub_zalloc (state[OPTION_PROTECTOR].set * sizeof (*cargs.key_cache));
+ if (cargs.key_cache == NULL)
+ return grub_error (GRUB_ERR_OUT_OF_MEMORY,
+ "no memory for key protector key cache");
+ cargs.protectors = state[OPTION_PROTECTOR].args;
+ }
+
if (state[OPTION_UUID].set) /* uuid */
{
int found_uuid;
@@ -1370,6 +1473,7 @@
dev = grub_cryptodisk_get_by_uuid (args[0]);
if (dev)
{
+ grub_cryptodisk_clear_key_cache (&cargs);
grub_dprintf ("cryptodisk",
"already mounted as crypto%lu\n", dev->id);
return GRUB_ERR_NONE;
@@ -1378,6 +1482,7 @@
cargs.check_boot = state[OPTION_BOOT].set;
cargs.search_uuid = args[0];
found_uuid = grub_device_iterate (&grub_cryptodisk_scan_device, &cargs);
+ grub_cryptodisk_clear_key_cache (&cargs);
if (found_uuid)
return GRUB_ERR_NONE;
@@ -1397,6 +1502,7 @@
{
cargs.check_boot = state[OPTION_BOOT].set;
grub_device_iterate (&grub_cryptodisk_scan_device, &cargs);
+ grub_cryptodisk_clear_key_cache (&cargs);
return GRUB_ERR_NONE;
}
else
@@ -1420,6 +1526,7 @@
disk = grub_disk_open (diskname);
if (!disk)
{
+ grub_cryptodisk_clear_key_cache (&cargs);
if (disklast)
*disklast = ')';
return grub_errno;
@@ -1430,12 +1537,14 @@
{
grub_dprintf ("cryptodisk", "already mounted as crypto%lu\n", dev->id);
grub_disk_close (disk);
+ grub_cryptodisk_clear_key_cache (&cargs);
if (disklast)
*disklast = ')';
return GRUB_ERR_NONE;
}
dev = grub_cryptodisk_scan_device_real (diskname, disk, &cargs);
+ grub_cryptodisk_clear_key_cache (&cargs);
grub_disk_close (disk);
if (disklast)
@@ -1576,6 +1685,7 @@
cmd = grub_register_extcmd ("cryptomount", grub_cmd_cryptomount, 0,
N_("[ [-p password] | [-k keyfile"
" [-O keyoffset] [-S keysize] ] ] [-H file]"
+ " [-P protector [-P protector ...]]"
" <SOURCE|-u UUID|-a|-b>"),
N_("Mount a crypto device."), options);
grub_procfs_register ("luks_script", &luks_script);
--- a/include/grub/cryptodisk.h
+++ b/include/grub/cryptodisk.h
@@ -70,6 +70,18 @@
(*grub_cryptodisk_rekey_func_t) (struct grub_cryptodisk *dev,
grub_uint64_t zoneno);
+struct grub_cryptomount_cached_key
+{
+ grub_uint8_t *key;
+ grub_size_t key_len;
+
+ /*
+ * The key protector associated with this cache entry failed, so avoid it
+ * even if the cached entry (an instance of this structure) is empty.
+ */
+ int invalid;
+};
+
struct grub_cryptomount_args
{
/* scan: Flag to indicate that only bootable volumes should be decrypted */
@@ -81,6 +93,10 @@
/* recover_key: Length of key_data */
grub_size_t key_len;
grub_file_t hdr_file;
+ /* recover_key: Names of the key protectors to use (NULL-terminated) */
+ char **protectors;
+ /* recover_key: Key cache to avoid invoking the same key protector twice */
+ struct grub_cryptomount_cached_key *key_cache;
};
typedef struct grub_cryptomount_args *grub_cryptomount_args_t;
