Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 383 insertions, 0 deletions

diff --git a/src/cryptenroll/cryptenroll-tpm2.c b/src/cryptenroll/cryptenroll-tpm2.c
new file mode 100644
index 0000000..653ad44
--- /dev/null
+++ b/src/cryptenroll/cryptenroll-tpm2.c
@@ -0,0 +1,383 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "alloc-util.h"
+#include "ask-password-api.h"
+#include "cryptenroll-tpm2.h"
+#include "env-util.h"
+#include "fileio.h"
+#include "hexdecoct.h"
+#include "json.h"
+#include "memory-util.h"
+#include "random-util.h"
+#include "sha256.h"
+#include "tpm2-util.h"
+
+static int search_policy_hash(
+                struct crypt_device *cd,
+                const void *hash,
+                size_t hash_size) {
+
+        int r;
+
+        assert(cd);
+        assert(hash || hash_size == 0);
+
+        if (hash_size == 0)
+                return 0;
+
+        for (int token = 0; token < sym_crypt_token_max(CRYPT_LUKS2); token ++) {
+                _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
+                _cleanup_free_ void *thash = NULL;
+                size_t thash_size = 0;
+                int keyslot;
+                JsonVariant *w;
+
+                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");
+
+                keyslot = cryptsetup_get_keyslot_from_token(v);
+                if (keyslot < 0) {
+                        /* Handle parsing errors of the keyslots field gracefully, since it's not 'owned' by
+                         * us, but by the LUKS2 spec */
+                        log_warning_errno(keyslot, "Failed to determine keyslot of JSON token %i, skipping: %m", token);
+                        continue;
+                }
+
+                w = json_variant_by_key(v, "tpm2-policy-hash");
+                if (!w || !json_variant_is_string(w))
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "TPM2 token data lacks 'tpm2-policy-hash' field.");
+
+                r = unhexmem(json_variant_string(w), SIZE_MAX, &thash, &thash_size);
+                if (r < 0)
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "Invalid base64 data in 'tpm2-policy-hash' field.");
+
+                if (memcmp_nn(hash, hash_size, thash, thash_size) == 0)
+                        return keyslot; /* Found entry with same hash. */
+        }
+
+        return -ENOENT; /* Not found */
+}
+
+static int get_pin(char **ret_pin_str, TPM2Flags *ret_flags) {
+        _cleanup_(erase_and_freep) char *pin_str = NULL;
+        TPM2Flags flags = 0;
+        int r;
+
+        assert(ret_pin_str);
+        assert(ret_flags);
+
+        r = getenv_steal_erase("NEWPIN", &pin_str);
+        if (r < 0)
+                return log_error_errno(r, "Failed to acquire PIN from environment: %m");
+        if (r > 0)
+                flags |= TPM2_FLAGS_USE_PIN;
+        else {
+                for (size_t i = 5;; i--) {
+                        _cleanup_strv_free_erase_ char **pin = NULL, **pin2 = NULL;
+
+                        if (i <= 0)
+                                return log_error_errno(
+                                                SYNTHETIC_ERRNO(ENOKEY), "Too many attempts, giving up.");
+
+                        pin = strv_free_erase(pin);
+                        r = ask_password_auto(
+                                        "Please enter TPM2 PIN:",
+                                        "drive-harddisk",
+                                        NULL,
+                                        "tpm2-pin",
+                                        "cryptenroll.tpm2-pin",
+                                        USEC_INFINITY,
+                                        0,
+                                        &pin);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to ask for user pin: %m");
+                        assert(strv_length(pin) == 1);
+
+                        r = ask_password_auto(
+                                        "Please enter TPM2 PIN (repeat):",
+                                        "drive-harddisk",
+                                        NULL,
+                                        "tpm2-pin",
+                                        "cryptenroll.tpm2-pin",
+                                        USEC_INFINITY,
+                                        0,
+                                        &pin2);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to ask for user pin: %m");
+                        assert(strv_length(pin) == 1);
+
+                        if (strv_equal(pin, pin2)) {
+                                pin_str = strdup(*pin);
+                                if (!pin_str)
+                                        return log_oom();
+                                flags |= TPM2_FLAGS_USE_PIN;
+                                break;
+                        }
+
+                        log_error("PINs didn't match, please try again!");
+                }
+        }
+
+        *ret_flags = flags;
+        *ret_pin_str = TAKE_PTR(pin_str);
+
+        return 0;
+}
+
+int enroll_tpm2(struct crypt_device *cd,
+                const void *volume_key,
+                size_t volume_key_size,
+                const char *device,
+                uint32_t seal_key_handle,
+                const char *device_key,
+                Tpm2PCRValue *hash_pcr_values,
+                size_t n_hash_pcr_values,
+                const char *pubkey_path,
+                uint32_t pubkey_pcr_mask,
+                const char *signature_path,
+                bool use_pin,
+                const char *pcrlock_path) {
+
+        _cleanup_(erase_and_freep) void *secret = NULL;
+        _cleanup_(json_variant_unrefp) JsonVariant *v = NULL, *signature_json = NULL;
+        _cleanup_(erase_and_freep) char *base64_encoded = NULL;
+        _cleanup_free_ void *srk_buf = NULL;
+        size_t secret_size, blob_size, pubkey_size = 0, srk_buf_size = 0;
+        _cleanup_free_ void *blob = NULL, *pubkey = NULL;
+        const char *node;
+        _cleanup_(erase_and_freep) char *pin_str = NULL;
+        ssize_t base64_encoded_size;
+        int r, keyslot;
+        TPM2Flags flags = 0;
+        uint8_t binary_salt[SHA256_DIGEST_SIZE] = {};
+        /*
+         * erase the salt, we'd rather attempt to not have this in a coredump
+         * as an attacker would have all the parameters but pin used to create
+         * the session key. This problem goes away when we move to a trusted
+         * primary key, aka the SRK.
+         */
+        CLEANUP_ERASE(binary_salt);
+
+        assert(cd);
+        assert(volume_key);
+        assert(volume_key_size > 0);
+        assert(tpm2_pcr_values_valid(hash_pcr_values, n_hash_pcr_values));
+        assert(TPM2_PCR_MASK_VALID(pubkey_pcr_mask));
+
+        assert_se(node = crypt_get_device_name(cd));
+
+        if (use_pin) {
+                r = get_pin(&pin_str, &flags);
+                if (r < 0)
+                        return r;
+
+                r = crypto_random_bytes(binary_salt, sizeof(binary_salt));
+                if (r < 0)
+                        return log_error_errno(r, "Failed to acquire random salt: %m");
+
+                uint8_t salted_pin[SHA256_DIGEST_SIZE] = {};
+                CLEANUP_ERASE(salted_pin);
+                r = tpm2_util_pbkdf2_hmac_sha256(pin_str, strlen(pin_str), binary_salt, sizeof(binary_salt), salted_pin);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to perform PBKDF2: %m");
+
+                pin_str = erase_and_free(pin_str);
+                /* re-stringify pin_str */
+                base64_encoded_size = base64mem(salted_pin, sizeof(salted_pin), &pin_str);
+                if (base64_encoded_size < 0)
+                        return log_error_errno(base64_encoded_size, "Failed to base64 encode salted pin: %m");
+        }
+
+        TPM2B_PUBLIC public = {};
+        r = tpm2_load_pcr_public_key(pubkey_path, &pubkey, &pubkey_size);
+        if (r < 0) {
+                if (pubkey_path || signature_path || r != -ENOENT)
+                        return log_error_errno(r, "Failed to read TPM PCR public key: %m");
+
+                log_debug_errno(r, "Failed to read TPM2 PCR public key, proceeding without: %m");
+                pubkey_pcr_mask = 0;
+        } else {
+                r = tpm2_tpm2b_public_from_pem(pubkey, pubkey_size, &public);
+                if (r < 0)
+                        return log_error_errno(r, "Could not convert public key to TPM2B_PUBLIC: %m");
+
+                if (signature_path) {
+                        /* Also try to load the signature JSON object, to verify that our enrollment will work.
+                         * This is optional however, skip it if it's not explicitly provided. */
+
+                        r = tpm2_load_pcr_signature(signature_path, &signature_json);
+                        if (r < 0)
+                                return log_debug_errno(r, "Failed to read TPM PCR signature: %m");
+                }
+        }
+
+        bool any_pcr_value_specified = tpm2_pcr_values_has_any_values(hash_pcr_values, n_hash_pcr_values);
+
+        _cleanup_(tpm2_pcrlock_policy_done) Tpm2PCRLockPolicy pcrlock_policy = {};
+        if (pcrlock_path) {
+                r = tpm2_pcrlock_policy_load(pcrlock_path, &pcrlock_policy);
+                if (r < 0)
+                        return r;
+
+                any_pcr_value_specified = true;
+                flags |= TPM2_FLAGS_USE_PCRLOCK;
+        }
+
+        _cleanup_(tpm2_context_unrefp) Tpm2Context *tpm2_context = NULL;
+        TPM2B_PUBLIC device_key_public = {};
+        if (device_key) {
+                r = tpm2_load_public_key_file(device_key, &device_key_public);
+                if (r < 0)
+                        return r;
+
+                if (!tpm2_pcr_values_has_all_values(hash_pcr_values, n_hash_pcr_values))
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "Must provide all PCR values when using TPM2 device key.");
+        } else {
+                r = tpm2_context_new(device, &tpm2_context);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to create TPM2 context: %m");
+
+                if (!tpm2_pcr_values_has_all_values(hash_pcr_values, n_hash_pcr_values)) {
+                        r = tpm2_pcr_read_missing_values(tpm2_context, hash_pcr_values, n_hash_pcr_values);
+                        if (r < 0)
+                                return log_error_errno(r, "Could not read pcr values: %m");
+                }
+        }
+
+        uint16_t hash_pcr_bank = 0;
+        uint32_t hash_pcr_mask = 0;
+        if (n_hash_pcr_values > 0) {
+                size_t hash_count;
+                r = tpm2_pcr_values_hash_count(hash_pcr_values, n_hash_pcr_values, &hash_count);
+                if (r < 0)
+                        return log_error_errno(r, "Could not get hash count: %m");
+
+                if (hash_count > 1)
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Multiple PCR banks selected.");
+
+                hash_pcr_bank = hash_pcr_values[0].hash;
+                r = tpm2_pcr_values_to_mask(hash_pcr_values, n_hash_pcr_values, hash_pcr_bank, &hash_pcr_mask);
+                if (r < 0)
+                        return log_error_errno(r, "Could not get hash mask: %m");
+        }
+
+        TPM2B_DIGEST policy = TPM2B_DIGEST_MAKE(NULL, TPM2_SHA256_DIGEST_SIZE);
+        r = tpm2_calculate_sealing_policy(
+                        hash_pcr_values,
+                        n_hash_pcr_values,
+                        pubkey ? &public : NULL,
+                        use_pin,
+                        pcrlock_path ? &pcrlock_policy : NULL,
+                        &policy);
+        if (r < 0)
+                return r;
+
+        if (device_key)
+                r = tpm2_calculate_seal(
+                                seal_key_handle,
+                                &device_key_public,
+                                /* attributes= */ NULL,
+                                /* secret= */ NULL, /* secret_size= */ 0,
+                                &policy,
+                                pin_str,
+                                &secret, &secret_size,
+                                &blob, &blob_size,
+                                &srk_buf, &srk_buf_size);
+        else
+                r = tpm2_seal(tpm2_context,
+                              seal_key_handle,
+                              &policy,
+                              pin_str,
+                              &secret, &secret_size,
+                              &blob, &blob_size,
+                              /* ret_primary_alg= */ NULL,
+                              &srk_buf, &srk_buf_size);
+        if (r < 0)
+                return log_error_errno(r, "Failed to seal to TPM2: %m");
+
+        /* Let's see if we already have this specific PCR policy hash enrolled, if so, exit early. */
+        r = search_policy_hash(cd, policy.buffer, policy.size);
+        if (r == -ENOENT)
+                log_debug_errno(r, "PCR policy hash not yet enrolled, enrolling now.");
+        else if (r < 0)
+                return r;
+        else {
+                log_info("This PCR set is already enrolled, executing no operation.");
+                return r; /* return existing keyslot, so that wiping won't kill it */
+        }
+
+        /* If possible, verify the sealed data object. */
+        if ((!pubkey || signature_json) && !any_pcr_value_specified && !device_key) {
+                _cleanup_(erase_and_freep) void *secret2 = NULL;
+                size_t secret2_size;
+
+                log_debug("Unsealing for verification...");
+                r = tpm2_unseal(tpm2_context,
+                                hash_pcr_mask,
+                                hash_pcr_bank,
+                                pubkey, pubkey_size,
+                                pubkey_pcr_mask,
+                                signature_json,
+                                pin_str,
+                                pcrlock_path ? &pcrlock_policy : NULL,
+                                /* primary_alg= */ 0,
+                                blob, blob_size,
+                                policy.buffer, policy.size,
+                                srk_buf, srk_buf_size,
+                                &secret2, &secret2_size);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to unseal secret using TPM2: %m");
+
+                if (memcmp_nn(secret, secret_size, secret2, secret2_size) != 0)
+                        return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "TPM2 seal/unseal verification failed.");
+        }
+
+        /* let's base64 encode the key to use, for compat with homed (and it's easier to every type it in by keyboard, if that might end up being necessary. */
+        base64_encoded_size = base64mem(secret, secret_size, &base64_encoded);
+        if (base64_encoded_size < 0)
+                return log_error_errno(base64_encoded_size, "Failed to base64 encode secret key: %m");
+
+        r = cryptsetup_set_minimal_pbkdf(cd);
+        if (r < 0)
+                return log_error_errno(r, "Failed to set minimal PBKDF: %m");
+
+        keyslot = crypt_keyslot_add_by_volume_key(
+                        cd,
+                        CRYPT_ANY_SLOT,
+                        volume_key,
+                        volume_key_size,
+                        base64_encoded,
+                        base64_encoded_size);
+        if (keyslot < 0)
+                return log_error_errno(keyslot, "Failed to add new TPM2 key to %s: %m", node);
+
+        r = tpm2_make_luks2_json(
+                        keyslot,
+                        hash_pcr_mask,
+                        hash_pcr_bank,
+                        pubkey, pubkey_size,
+                        pubkey_pcr_mask,
+                        /* primary_alg= */ 0,
+                        blob, blob_size,
+                        policy.buffer, policy.size,
+                        use_pin ? binary_salt : NULL,
+                        use_pin ? sizeof(binary_salt) : 0,
+                        srk_buf, srk_buf_size,
+                        flags,
+                        &v);
+        if (r < 0)
+                return log_error_errno(r, "Failed to prepare TPM2 JSON token object: %m");
+
+        r = cryptsetup_add_token_json(cd, v);
+        if (r < 0)
+                return log_error_errno(r, "Failed to add TPM2 JSON token to LUKS2 header: %m");
+
+        log_info("New TPM2 token enrolled as key slot %i.", keyslot);
+        return keyslot;
+}