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Re: [PATCH v2 10/11] cryptodisk: Support key protectors
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From: |
Glenn Washburn |
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Subject: |
Re: [PATCH v2 10/11] cryptodisk: Support key protectors |
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Date: |
Fri, 24 Mar 2023 03:21:57 +0000 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 |
On 3/22/23 08:10, Gary Lin wrote:
From: Hernan Gatta <hegatta@linux.microsoft.com>
Add a new parameter to cryptomount to support the key protectors framework: -P.
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>
Signed-off-by: Michael Chang <mchang@suse.com>
I'm wondering, why Michael's SOB is needed here? Did I miss somewhere on
the list where he contributed to this patch?
Signed-off-by: Gary Lin <glin@suse.com>
---
Makefile.util.def | 1 +
grub-core/disk/cryptodisk.c | 175 +++++++++++++++++++++++++++++-------
include/grub/cryptodisk.h | 14 +++
3 files changed, 158 insertions(+), 32 deletions(-)
diff --git a/Makefile.util.def b/Makefile.util.def
index c3b7df96d..7d8db722e 100644
--- a/Makefile.util.def
+++ b/Makefile.util.def
@@ -35,6 +35,7 @@ library = {
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;
diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c
index 34b67a705..c5974399e 100644
--- 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 @@ enum
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 @@ static const struct grub_arg_option options[] =
{"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}
};
@@ -1060,7 +1064,8 @@ grub_cryptodisk_scan_device_real (const char *name,
{
grub_err_t ret = GRUB_ERR_NONE;
grub_cryptodisk_t dev;
- grub_cryptodisk_dev_t cr;
+ grub_cryptodisk_dev_t cr, crd = NULL;
+ int i;
struct cryptodisk_read_hook_ctx read_hook_data = {0};
int askpass = 0;
char *part = NULL;
@@ -1113,41 +1118,113 @@ grub_cryptodisk_scan_device_real (const char *name,
goto error_no_close;
if (!dev)
continue;
+ crd = cr;
Why can't we just use cr below and not introduce crd?
+ 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 (!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 (!dev)
+ {
+ grub_error (GRUB_ERR_BAD_MODULE,
+ "no cryptodisk module can handle this device");
Every 8 spaces should be converted to a tab character. Same for all
instances below too (and probably in other patches, though not in the
ones importing foreign libs, like libtasn).
+ goto error_no_close;
+ }
- ret = cr->recover_key (source, dev, cargs);
- if (ret != GRUB_ERR_NONE)
- goto error;
+ if (cargs->protectors)
+ {
+ for (i = 0; cargs->protectors[i]; i++)
+ {
+ if (cargs->key_cache[i].invalid)
+ continue;
+
+ if (!cargs->key_cache[i].key)
+ {
+ ret = grub_key_protector_recover_key (cargs->protectors[i],
+ &cargs->key_cache[i].key,
+
&cargs->key_cache[i].key_len);
+ if (ret)
Daniel will say this should be "ret != GRUB_ERR_NONE", and same for
similar uses elsewhere.
+ {
+ 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 = crd->recover_key (source, dev, cargs);
+ if (ret) > + {
+ 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 = crd->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 +1335,20 @@ grub_cryptodisk_scan_device (const char *name,
return ret;
}
+static void
+grub_cryptodisk_clear_key_cache (struct grub_cryptomount_args *cargs)
+{
+ int i;
+
+ if (!cargs->key_cache)
Daniel also prefers "cargs->key_cache == NULL" for NULL checks on pointers.
+ return;
+
+ for (i = 0; cargs->protectors[i]; i++)
Maybe good to be defensive and check that cargs->protectors is not NULL.
+ 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 +1361,10 @@ grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int
argc, char **args)
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 +1457,15 @@ grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int
argc, char **args)
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)
+ 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 +1474,7 @@ grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int
argc, char **args)
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 +1483,7 @@ grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int
argc, char **args)
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 +1503,7 @@ grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int
argc, char **args)
{
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 +1527,7 @@ grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int
argc, char **args)
disk = grub_disk_open (diskname);
if (!disk)
{
+ grub_cryptodisk_clear_key_cache (&cargs);
if (disklast)
*disklast = ')';
return grub_errno;
@@ -1430,12 +1538,14 @@ grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int
argc, char **args)
{
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 +1686,7 @@ GRUB_MOD_INIT (cryptodisk)
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);
diff --git a/include/grub/cryptodisk.h b/include/grub/cryptodisk.h
index d94df68b6..ce18df883 100644
--- a/include/grub/cryptodisk.h
+++ b/include/grub/cryptodisk.h
@@ -70,6 +70,16 @@ typedef gcry_err_code_t
(*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. */
Not a properly formatted multiline comment[1].
Overall this looks okay, even if I'm still not in love with the key
protectors user interface (but like the idea).
Glenn
[1]
https://www.gnu.org/software/grub/manual/grub-dev/grub-dev.html#Multi_002dLine-Comments
+ int invalid;
+};
+
struct grub_cryptomount_args
{
/* scan: Flag to indicate that only bootable volumes should be decrypted */
@@ -81,6 +91,10 @@ struct grub_cryptomount_args
/* 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;
- [PATCH v2 01/11] posix_wrap: tweaks in preparation for libtasn1, (continued)
- [PATCH v2 01/11] posix_wrap: tweaks in preparation for libtasn1, Gary Lin, 2023/03/22
- [PATCH v2 05/11] libtasn1: compile into asn1 module, Gary Lin, 2023/03/22
- [PATCH v2 02/11] libtasn1: import libtasn1-4.19.0, Gary Lin, 2023/03/22
- [PATCH v2 03/11] libtasn1: disable code not needed in grub, Gary Lin, 2023/03/22
- [PATCH v2 04/11] libtasn1: changes for grub compatibility, Gary Lin, 2023/03/22
- [PATCH v2 06/11] test_asn1: test module for libtasn1, Gary Lin, 2023/03/22
- [PATCH v2 07/11] protectors: Add key protectors framework, Gary Lin, 2023/03/22
- [PATCH v2 08/11] tpm2: Add TPM Software Stack (TSS), Gary Lin, 2023/03/22
- [PATCH v2 09/11] protectors: Add TPM2 Key Protector, Gary Lin, 2023/03/22
- [PATCH v2 10/11] cryptodisk: Support key protectors, Gary Lin, 2023/03/22
- Re: [PATCH v2 10/11] cryptodisk: Support key protectors,
Glenn Washburn <=
- [PATCH v2 11/11] util/grub-protect: Add new tool, Gary Lin, 2023/03/22
- Re: [PATCH v2 00/11] Automatic Disk Unlock with TPM2, Glenn Washburn, 2023/03/23