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-rw-r--r--src/cryptsetup/cryptsetup-tpm2.c314
1 files changed, 314 insertions, 0 deletions
diff --git a/src/cryptsetup/cryptsetup-tpm2.c b/src/cryptsetup/cryptsetup-tpm2.c
new file mode 100644
index 0000000..f59d5f9
--- /dev/null
+++ b/src/cryptsetup/cryptsetup-tpm2.c
@@ -0,0 +1,314 @@
+/* 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"
+#include "parse-util.h"
+#include "random-util.h"
+#include "sha256.h"
+#include "tpm2-util.h"
+
+static int get_pin(usec_t until, AskPasswordFlags ask_password_flags, bool headless, char **ret_pin_str) {
+ _cleanup_(erase_and_freep) 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,
+ uint32_t hash_pcr_mask,
+ uint16_t pcr_bank,
+ const void *pubkey,
+ size_t pubkey_size,
+ uint32_t pubkey_pcr_mask,
+ const char *signature_path,
+ const char *pcrlock_path,
+ uint16_t primary_alg,
+ const char *key_file,
+ size_t key_file_size,
+ uint64_t key_file_offset,
+ const void *key_data,
+ size_t key_data_size,
+ const void *policy_hash,
+ size_t policy_hash_size,
+ const void *salt,
+ size_t salt_size,
+ const void *srk_buf,
+ size_t srk_buf_size,
+ TPM2Flags flags,
+ usec_t until,
+ bool headless,
+ AskPasswordFlags ask_password_flags,
+ void **ret_decrypted_key,
+ size_t *ret_decrypted_key_size) {
+
+ _cleanup_(json_variant_unrefp) JsonVariant *signature_json = NULL;
+ _cleanup_free_ void *loaded_blob = NULL;
+ _cleanup_free_ char *auto_device = NULL;
+ size_t blob_size;
+ const void *blob;
+ int r;
+
+ assert(salt || salt_size == 0);
+
+ if (!device) {
+ r = tpm2_find_device_auto(&auto_device);
+ if (r == -ENODEV)
+ return -EAGAIN; /* Tell the caller to wait for a TPM2 device to show up */
+ if (r < 0)
+ return log_error_errno(r, "Could not find TPM2 device: %m");
+
+ device = auto_device;
+ }
+
+ if (key_data) {
+ blob = key_data;
+ blob_size = key_data_size;
+ } else {
+ _cleanup_free_ char *bindname = NULL;
+
+ /* If we read the salt via AF_UNIX, make this client recognizable */
+ if (asprintf(&bindname, "@%" PRIx64"/cryptsetup-tpm2/%s", random_u64(), volume_name) < 0)
+ return log_oom();
+
+ r = read_full_file_full(
+ AT_FDCWD, key_file,
+ key_file_offset == 0 ? UINT64_MAX : key_file_offset,
+ key_file_size == 0 ? SIZE_MAX : key_file_size,
+ READ_FULL_FILE_CONNECT_SOCKET,
+ bindname,
+ (char**) &loaded_blob, &blob_size);
+ if (r < 0)
+ return r;
+
+ blob = loaded_blob;
+ }
+
+ if (pubkey_pcr_mask != 0) {
+ r = tpm2_load_pcr_signature(signature_path, &signature_json);
+ if (r < 0)
+ return log_error_errno(r, "Failed to load pcr signature: %m");
+ }
+
+ _cleanup_(tpm2_pcrlock_policy_done) Tpm2PCRLockPolicy pcrlock_policy = {};
+
+ if (FLAGS_SET(flags, TPM2_FLAGS_USE_PCRLOCK)) {
+ r = tpm2_pcrlock_policy_load(pcrlock_path, &pcrlock_policy);
+ if (r < 0)
+ return r;
+ }
+
+ _cleanup_(tpm2_context_unrefp) Tpm2Context *tpm2_context = NULL;
+ r = tpm2_context_new(device, &tpm2_context);
+ if (r < 0)
+ return log_error_errno(r, "Failed to create TPM2 context: %m");
+
+ if (!(flags & TPM2_FLAGS_USE_PIN)) {
+ r = tpm2_unseal(tpm2_context,
+ hash_pcr_mask,
+ pcr_bank,
+ pubkey, pubkey_size,
+ pubkey_pcr_mask,
+ signature_json,
+ /* pin= */ NULL,
+ FLAGS_SET(flags, TPM2_FLAGS_USE_PCRLOCK) ? &pcrlock_policy : NULL,
+ primary_alg,
+ blob,
+ blob_size,
+ policy_hash,
+ policy_hash_size,
+ srk_buf,
+ srk_buf_size,
+ ret_decrypted_key,
+ ret_decrypted_key_size);
+ if (r < 0)
+ return log_error_errno(r, "Failed to unseal secret using TPM2: %m");
+
+ return r;
+ }
+
+ for (int i = 5;; i--) {
+ _cleanup_(erase_and_freep) char *pin_str = NULL, *b64_salted_pin = NULL;
+
+ if (i <= 0)
+ return -EACCES;
+
+ r = get_pin(until, ask_password_flags, headless, &pin_str);
+ if (r < 0)
+ return r;
+
+ if (salt_size > 0) {
+ uint8_t salted_pin[SHA256_DIGEST_SIZE] = {};
+ CLEANUP_ERASE(salted_pin);
+
+ r = tpm2_util_pbkdf2_hmac_sha256(pin_str, strlen(pin_str), salt, salt_size, salted_pin);
+ if (r < 0)
+ return log_error_errno(r, "Failed to perform PBKDF2: %m");
+
+ r = base64mem(salted_pin, sizeof(salted_pin), &b64_salted_pin);
+ if (r < 0)
+ return log_error_errno(r, "Failed to base64 encode salted pin: %m");
+ } else
+ /* no salting needed, backwards compat with non-salted pins */
+ b64_salted_pin = TAKE_PTR(pin_str);
+
+ r = tpm2_unseal(tpm2_context,
+ hash_pcr_mask,
+ pcr_bank,
+ pubkey, pubkey_size,
+ pubkey_pcr_mask,
+ signature_json,
+ b64_salted_pin,
+ pcrlock_path ? &pcrlock_policy : NULL,
+ primary_alg,
+ blob,
+ blob_size,
+ policy_hash,
+ policy_hash_size,
+ srk_buf,
+ srk_buf_size,
+ ret_decrypted_key,
+ ret_decrypted_key_size);
+ if (r < 0) {
+ log_error_errno(r, "Failed to unseal secret using TPM2: %m");
+
+ /* 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))
+ continue;
+ }
+
+ return r;
+ }
+}
+
+int find_tpm2_auto_data(
+ struct crypt_device *cd,
+ uint32_t search_pcr_mask,
+ int start_token,
+ uint32_t *ret_hash_pcr_mask,
+ uint16_t *ret_pcr_bank,
+ void **ret_pubkey,
+ size_t *ret_pubkey_size,
+ uint32_t *ret_pubkey_pcr_mask,
+ uint16_t *ret_primary_alg,
+ void **ret_blob,
+ size_t *ret_blob_size,
+ void **ret_policy_hash,
+ size_t *ret_policy_hash_size,
+ void **ret_salt,
+ size_t *ret_salt_size,
+ void **ret_srk_buf,
+ size_t *ret_srk_buf_size,
+ TPM2Flags *ret_flags,
+ int *ret_keyslot,
+ int *ret_token) {
+
+ int r, token;
+
+ assert(cd);
+
+ for (token = start_token; token < sym_crypt_token_max(CRYPT_LUKS2); token++) {
+ _cleanup_free_ void *blob = NULL, *policy_hash = NULL, *pubkey = NULL, *salt = NULL, *srk_buf = NULL;
+ _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
+ size_t blob_size, policy_hash_size, pubkey_size, salt_size = 0, srk_buf_size = 0;
+ uint32_t hash_pcr_mask, pubkey_pcr_mask;
+ uint16_t pcr_bank, primary_alg;
+ TPM2Flags flags;
+ int keyslot;
+
+ r = cryptsetup_get_token_as_json(cd, token, "systemd-tpm2", &v);
+ if (IN_SET(r, -ENOENT, -EINVAL, -EMEDIUMTYPE))
+ continue;
+ if (r < 0)
+ return log_error_errno(r, "Failed to read JSON token data off disk: %m");
+
+ r = tpm2_parse_luks2_json(
+ v,
+ &keyslot,
+ &hash_pcr_mask,
+ &pcr_bank,
+ &pubkey, &pubkey_size,
+ &pubkey_pcr_mask,
+ &primary_alg,
+ &blob, &blob_size,
+ &policy_hash, &policy_hash_size,
+ &salt, &salt_size,
+ &srk_buf, &srk_buf_size,
+ &flags);
+ if (r == -EUCLEAN) /* Gracefully handle issues in JSON fields not owned by us */
+ continue;
+ if (r < 0)
+ return log_error_errno(r, "Failed to parse TPM2 JSON data: %m");
+
+ if (search_pcr_mask == UINT32_MAX ||
+ search_pcr_mask == hash_pcr_mask) {
+
+ if (start_token <= 0)
+ log_info("Automatically discovered security TPM2 token unlocks volume.");
+
+ *ret_hash_pcr_mask = hash_pcr_mask;
+ *ret_pcr_bank = pcr_bank;
+ *ret_pubkey = TAKE_PTR(pubkey);
+ *ret_pubkey_size = pubkey_size;
+ *ret_pubkey_pcr_mask = pubkey_pcr_mask;
+ *ret_primary_alg = primary_alg;
+ *ret_blob = TAKE_PTR(blob);
+ *ret_blob_size = blob_size;
+ *ret_policy_hash = TAKE_PTR(policy_hash);
+ *ret_policy_hash_size = policy_hash_size;
+ *ret_salt = TAKE_PTR(salt);
+ *ret_salt_size = salt_size;
+ *ret_keyslot = keyslot;
+ *ret_token = token;
+ *ret_srk_buf = TAKE_PTR(srk_buf);
+ *ret_srk_buf_size = srk_buf_size;
+ *ret_flags = flags;
+ return 0;
+ }
+
+ /* PCR mask doesn't match what is configured, ignore this entry, let's see next */
+ }
+
+ return log_error_errno(SYNTHETIC_ERRNO(ENXIO), "No valid TPM2 token data found.");
+}
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