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systemd/SOURCES/0226-cryptsetup-add-support...

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From 2418e9c1409ba04ddff516a83d83b2daa3417832 Mon Sep 17 00:00:00 2001
From: Grigori Goronzy <greg@chown.ath.cx>
Date: Fri, 18 Feb 2022 11:56:02 +0100
Subject: [PATCH] cryptsetup: add support for TPM2 pin
Extend cryptsetup for TPM2 pin entry, similar to FIDO2.
(cherry picked from commit bea344a1a426e615ba87b66b6d3ff4b265c57a95)
Related: #2087652
---
src/cryptsetup/cryptsetup-tpm2.c | 108 ++++++++++++++++++++++++++++++-
src/cryptsetup/cryptsetup-tpm2.h | 16 ++++-
src/cryptsetup/cryptsetup.c | 16 ++++-
3 files changed, 135 insertions(+), 5 deletions(-)
diff --git a/src/cryptsetup/cryptsetup-tpm2.c b/src/cryptsetup/cryptsetup-tpm2.c
index 05d76a684d..b84d64def8 100644
--- a/src/cryptsetup/cryptsetup-tpm2.c
+++ b/src/cryptsetup/cryptsetup-tpm2.c
@@ -1,7 +1,9 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include "alloc-util.h"
+#include "ask-password-api.h"
#include "cryptsetup-tpm2.h"
+#include "env-util.h"
#include "fileio.h"
#include "hexdecoct.h"
#include "json.h"
@@ -9,6 +11,47 @@
#include "random-util.h"
#include "tpm2-util.h"
+static int get_pin(usec_t until, AskPasswordFlags ask_password_flags, bool headless, char **ret_pin_str) {
+ _cleanup_free_ char *pin_str = NULL;
+ _cleanup_strv_free_erase_ char **pin = NULL;
+ int r;
+
+ assert(ret_pin_str);
+
+ r = getenv_steal_erase("PIN", &pin_str);
+ if (r < 0)
+ return log_error_errno(r, "Failed to acquire PIN from environment: %m");
+ if (!r) {
+ if (headless)
+ return log_error_errno(
+ SYNTHETIC_ERRNO(ENOPKG),
+ "PIN querying disabled via 'headless' option. "
+ "Use the '$PIN' environment variable.");
+
+ pin = strv_free_erase(pin);
+ r = ask_password_auto(
+ "Please enter TPM2 PIN:",
+ "drive-harddisk",
+ NULL,
+ "tpm2-pin",
+ "cryptsetup.tpm2-pin",
+ until,
+ ask_password_flags,
+ &pin);
+ if (r < 0)
+ return log_error_errno(r, "Failed to ask for user pin: %m");
+ assert(strv_length(pin) == 1);
+
+ pin_str = strdup(pin[0]);
+ if (!pin_str)
+ return log_oom();
+ }
+
+ *ret_pin_str = TAKE_PTR(pin_str);
+
+ return r;
+}
+
int acquire_tpm2_key(
const char *volume_name,
const char *device,
@@ -22,6 +65,10 @@ int acquire_tpm2_key(
size_t key_data_size,
const void *policy_hash,
size_t policy_hash_size,
+ TPM2Flags flags,
+ usec_t until,
+ bool headless,
+ AskPasswordFlags ask_password_flags,
void **ret_decrypted_key,
size_t *ret_decrypted_key_size) {
@@ -64,7 +111,51 @@ int acquire_tpm2_key(
blob = loaded_blob;
}
- return tpm2_unseal(device, pcr_mask, pcr_bank, primary_alg, blob, blob_size, policy_hash, policy_hash_size, NULL, ret_decrypted_key, ret_decrypted_key_size);
+ if (!(flags & TPM2_FLAGS_USE_PIN))
+ return tpm2_unseal(
+ device,
+ pcr_mask,
+ pcr_bank,
+ primary_alg,
+ blob,
+ blob_size,
+ policy_hash,
+ policy_hash_size,
+ NULL,
+ ret_decrypted_key,
+ ret_decrypted_key_size);
+
+ for (int i = 5;; i--) {
+ _cleanup_(erase_and_freep) char *pin_str = NULL;
+
+ if (i <= 0)
+ return -EACCES;
+
+ r = get_pin(until, ask_password_flags, headless, &pin_str);
+ if (r < 0)
+ return r;
+
+ r = tpm2_unseal(
+ device,
+ pcr_mask,
+ pcr_bank,
+ primary_alg,
+ blob,
+ blob_size,
+ policy_hash,
+ policy_hash_size,
+ pin_str,
+ ret_decrypted_key,
+ ret_decrypted_key_size);
+ /* We get this error in case there is an authentication policy mismatch. This should
+ * not happen, but this avoids confusing behavior, just in case. */
+ if (IN_SET(r, -EPERM, -ENOLCK))
+ return r;
+ if (r < 0)
+ continue;
+
+ return r;
+ }
}
int find_tpm2_auto_data(
@@ -79,11 +170,13 @@ int find_tpm2_auto_data(
void **ret_policy_hash,
size_t *ret_policy_hash_size,
int *ret_keyslot,
- int *ret_token) {
+ int *ret_token,
+ TPM2Flags *ret_flags) {
_cleanup_free_ void *blob = NULL, *policy_hash = NULL;
size_t blob_size = 0, policy_hash_size = 0;
int r, keyslot = -1, token = -1;
+ TPM2Flags flags = 0;
uint32_t pcr_mask = 0;
uint16_t pcr_bank = UINT16_MAX; /* default: pick automatically */
uint16_t primary_alg = TPM2_ALG_ECC; /* ECC was the only supported algorithm in systemd < 250, use that as implied default, for compatibility */
@@ -196,6 +289,16 @@ int find_tpm2_auto_data(
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Invalid base64 data in 'tpm2-policy-hash' field.");
+ w = json_variant_by_key(v, "tpm2-pin");
+ if (w) {
+ if (!json_variant_is_boolean(w))
+ return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+ "TPM2 PIN policy is not a boolean.");
+
+ if (json_variant_boolean(w))
+ flags |= TPM2_FLAGS_USE_PIN;
+ }
+
break;
}
@@ -215,6 +318,7 @@ int find_tpm2_auto_data(
*ret_token = token;
*ret_pcr_bank = pcr_bank;
*ret_primary_alg = primary_alg;
+ *ret_flags = flags;
return 0;
}
diff --git a/src/cryptsetup/cryptsetup-tpm2.h b/src/cryptsetup/cryptsetup-tpm2.h
index bd04620462..ab16d0a18f 100644
--- a/src/cryptsetup/cryptsetup-tpm2.h
+++ b/src/cryptsetup/cryptsetup-tpm2.h
@@ -3,9 +3,11 @@
#include <sys/types.h>
+#include "ask-password-api.h"
#include "cryptsetup-util.h"
#include "log.h"
#include "time-util.h"
+#include "tpm2-util.h"
#if HAVE_TPM2
@@ -22,6 +24,10 @@ int acquire_tpm2_key(
size_t key_data_size,
const void *policy_hash,
size_t policy_hash_size,
+ TPM2Flags flags,
+ usec_t until,
+ bool headless,
+ AskPasswordFlags ask_password_flags,
void **ret_decrypted_key,
size_t *ret_decrypted_key_size);
@@ -37,7 +43,8 @@ int find_tpm2_auto_data(
void **ret_policy_hash,
size_t *ret_policy_hash_size,
int *ret_keyslot,
- int *ret_token);
+ int *ret_token,
+ TPM2Flags *ret_flags);
#else
@@ -54,6 +61,10 @@ static inline int acquire_tpm2_key(
size_t key_data_size,
const void *policy_hash,
size_t policy_hash_size,
+ TPM2Flags flags,
+ usec_t until,
+ bool headless,
+ AskPasswordFlags ask_password_flags,
void **ret_decrypted_key,
size_t *ret_decrypted_key_size) {
@@ -73,7 +84,8 @@ static inline int find_tpm2_auto_data(
void **ret_policy_hash,
size_t *ret_policy_hash_size,
int *ret_keyslot,
- int *ret_token) {
+ int *ret_token,
+ TPM2Flags *ret_flags) {
return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
"TPM2 support not available.");
diff --git a/src/cryptsetup/cryptsetup.c b/src/cryptsetup/cryptsetup.c
index dddd976dc8..ede0f7ed0b 100644
--- a/src/cryptsetup/cryptsetup.c
+++ b/src/cryptsetup/cryptsetup.c
@@ -1301,9 +1301,15 @@ static int attach_luks_or_plain_or_bitlk_by_tpm2(
key_file, arg_keyfile_size, arg_keyfile_offset,
key_data, key_data_size,
NULL, 0, /* we don't know the policy hash */
+ 0, /* PIN is currently unhandled in this case */
+ until,
+ arg_headless,
+ arg_ask_password_flags,
&decrypted_key, &decrypted_key_size);
if (r >= 0)
break;
+ if (IN_SET(r, -EACCES, -ENOLCK))
+ return log_error_errno(SYNTHETIC_ERRNO(EAGAIN), "TPM2 PIN unlock failed, falling back to traditional unlocking.");
if (ERRNO_IS_NOT_SUPPORTED(r)) /* TPM2 support not compiled in? */
return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN), "TPM2 support not available, falling back to traditional unlocking.");
if (r != -EAGAIN) /* EAGAIN means: no tpm2 chip found */
@@ -1335,6 +1341,7 @@ static int attach_luks_or_plain_or_bitlk_by_tpm2(
for (;;) {
uint32_t pcr_mask;
uint16_t pcr_bank, primary_alg;
+ TPM2Flags tpm2_flags;
r = find_tpm2_auto_data(
cd,
@@ -1346,7 +1353,8 @@ static int attach_luks_or_plain_or_bitlk_by_tpm2(
&blob, &blob_size,
&policy_hash, &policy_hash_size,
&keyslot,
- &token);
+ &token,
+ &tpm2_flags);
if (r == -ENXIO)
/* No further TPM2 tokens found in the LUKS2 header. */
return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN),
@@ -1369,7 +1377,13 @@ static int attach_luks_or_plain_or_bitlk_by_tpm2(
NULL, 0, 0, /* no key file */
blob, blob_size,
policy_hash, policy_hash_size,
+ tpm2_flags,
+ until,
+ arg_headless,
+ arg_ask_password_flags,
&decrypted_key, &decrypted_key_size);
+ if (IN_SET(r, -EACCES, -ENOLCK))
+ return log_error_errno(SYNTHETIC_ERRNO(EAGAIN), "TPM2 PIN unlock failed, falling back to traditional unlocking.");
if (r != -EPERM)
break;