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