cryptsetup: add support for TPM2 unlocking of volumes
This commit is contained in:
Lennart Poettering
+228
-4
@@ -14,6 +14,7 @@
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#include "cryptsetup-fido2.h"
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#include "cryptsetup-keyfile.h"
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#include "cryptsetup-pkcs11.h"
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#include "cryptsetup-tpm2.h"
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#include "cryptsetup-util.h"
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#include "device-util.h"
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#include "escape.h"
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@@ -34,6 +35,7 @@
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#include "random-util.h"
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#include "string-util.h"
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#include "strv.h"
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#include "tpm2-util.h"
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/* internal helper */
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#define ANY_LUKS "LUKS"
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@@ -72,6 +74,9 @@ static bool arg_fido2_device_auto = false;
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static void *arg_fido2_cid = NULL;
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static size_t arg_fido2_cid_size = 0;
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static char *arg_fido2_rp_id = NULL;
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static char *arg_tpm2_device = NULL;
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static bool arg_tpm2_device_auto = false;
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static uint32_t arg_tpm2_pcr_mask = UINT32_MAX;
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STATIC_DESTRUCTOR_REGISTER(arg_cipher, freep);
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STATIC_DESTRUCTOR_REGISTER(arg_hash, freep);
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@@ -81,6 +86,7 @@ STATIC_DESTRUCTOR_REGISTER(arg_pkcs11_uri, freep);
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STATIC_DESTRUCTOR_REGISTER(arg_fido2_device, freep);
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STATIC_DESTRUCTOR_REGISTER(arg_fido2_cid, freep);
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STATIC_DESTRUCTOR_REGISTER(arg_fido2_rp_id, freep);
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STATIC_DESTRUCTOR_REGISTER(arg_tpm2_device, freep);
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/* Options Debian's crypttab knows we don't:
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@@ -327,6 +333,36 @@ static int parse_one_option(const char *option) {
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if (r < 0)
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return log_oom();
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} else if ((val = startswith(option, "tpm2-device="))) {
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if (streq(val, "auto")) {
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arg_tpm2_device = mfree(arg_tpm2_device);
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arg_tpm2_device_auto = true;
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} else {
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r = free_and_strdup(&arg_tpm2_device, val);
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if (r < 0)
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return log_oom();
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arg_tpm2_device_auto = false;
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}
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} else if ((val = startswith(option, "tpm2-pcrs="))) {
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if (isempty(val))
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arg_tpm2_pcr_mask = 0;
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else {
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uint32_t mask;
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r = tpm2_parse_pcrs(val, &mask);
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if (r < 0)
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return r;
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if (arg_tpm2_pcr_mask == UINT32_MAX)
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arg_tpm2_pcr_mask = mask;
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else
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arg_tpm2_pcr_mask |= mask;
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}
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} else if ((val = startswith(option, "try-empty-password="))) {
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r = parse_boolean(val);
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@@ -556,10 +592,10 @@ static int attach_tcrypt(
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assert(name);
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assert(key_file || key_data || !strv_isempty(passwords));
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if (arg_pkcs11_uri || arg_pkcs11_uri_auto || arg_fido2_device || arg_fido2_device_auto)
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if (arg_pkcs11_uri || arg_pkcs11_uri_auto || arg_fido2_device || arg_fido2_device_auto || arg_tpm2_device || arg_tpm2_device_auto)
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/* Ask for a regular password */
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return log_error_errno(SYNTHETIC_ERRNO(EAGAIN),
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"Sorry, but tcrypt devices are currently not supported in conjunction with pkcs11/fido2 support.");
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"Sorry, but tcrypt devices are currently not supported in conjunction with pkcs11/fido2/tpm2 support.");
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if (arg_tcrypt_hidden)
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params.flags |= CRYPT_TCRYPT_HIDDEN_HEADER;
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@@ -907,6 +943,190 @@ static int attach_luks_or_plain_or_bitlk_by_pkcs11(
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return 0;
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}
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static int make_tpm2_device_monitor(sd_event *event, sd_device_monitor **ret) {
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_cleanup_(sd_device_monitor_unrefp) sd_device_monitor *monitor = NULL;
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int r;
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assert(ret);
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r = sd_device_monitor_new(&monitor);
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if (r < 0)
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return log_error_errno(r, "Failed to allocate device monitor: %m");
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r = sd_device_monitor_filter_add_match_subsystem_devtype(monitor, "tpmrm", NULL);
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if (r < 0)
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return log_error_errno(r, "Failed to configure device monitor: %m");
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r = sd_device_monitor_attach_event(monitor, event);
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if (r < 0)
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return log_error_errno(r, "Failed to attach device monitor: %m");
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r = sd_device_monitor_start(monitor, NULL, NULL);
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if (r < 0)
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return log_error_errno(r, "Failed to start device monitor: %m");
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*ret = TAKE_PTR(monitor);
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return 0;
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}
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static int attach_luks_or_plain_or_bitlk_by_tpm2(
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struct crypt_device *cd,
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const char *name,
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const char *key_file,
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const void *key_data,
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size_t key_data_size,
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usec_t until,
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uint32_t flags,
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bool pass_volume_key) {
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_cleanup_(sd_device_monitor_unrefp) sd_device_monitor *monitor = NULL;
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_cleanup_(erase_and_freep) void *decrypted_key = NULL;
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_cleanup_(sd_event_unrefp) sd_event *event = NULL;
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_cleanup_free_ char *friendly = NULL;
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int keyslot = arg_key_slot, r;
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size_t decrypted_key_size;
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assert(cd);
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assert(name);
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assert(arg_tpm2_device || arg_tpm2_device_auto);
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friendly = friendly_disk_name(crypt_get_device_name(cd), name);
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if (!friendly)
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return log_oom();
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for (;;) {
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bool processed = false;
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if (key_file || key_data) {
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/* If key data is specified, use that */
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r = acquire_tpm2_key(
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name,
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arg_tpm2_device,
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arg_tpm2_pcr_mask == UINT32_MAX ? TPM2_PCR_MASK_DEFAULT : arg_tpm2_pcr_mask,
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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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&decrypted_key, &decrypted_key_size);
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if (r >= 0)
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break;
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if (r != -EAGAIN) /* EAGAIN means: no tpm2 chip found */
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return r;
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} else {
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_cleanup_free_ void *blob = NULL, *policy_hash = NULL;
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size_t blob_size, policy_hash_size;
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bool found_some = false;
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int token = 0; /* first token to look at */
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/* If no key data is specified, look for it in the header. In order to support
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* software upgrades we'll iterate through all suitable tokens, maybe one of them
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* works. */
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for (;;) {
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uint32_t pcr_mask;
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r = find_tpm2_auto_data(
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cd,
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arg_tpm2_pcr_mask, /* if != UINT32_MAX we'll only look for tokens with this PCR mask */
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token, /* search for the token with this index, or any later index than this */
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&pcr_mask,
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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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if (r == -ENXIO) {
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/* No futher TPM2 tokens found in the LUKS2 header.*/
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if (found_some)
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return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN),
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"No TPM2 metadata matching the current system state found in LUKS2 header, falling back to traditional unlocking.");
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else
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return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN),
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"No TPM2 metadata enrolled in LUKS2 header, falling back to traditional unlocking.");
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}
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if (r < 0)
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return r;
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found_some = true;
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r = acquire_tpm2_key(
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name,
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arg_tpm2_device,
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pcr_mask,
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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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&decrypted_key, &decrypted_key_size);
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if (r != -EPERM)
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break;
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token++; /* try a different token next time */
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}
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if (r >= 0)
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break;
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if (r != -EAGAIN) /* EAGAIN means: no tpm2 chip found */
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return r;
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}
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if (!monitor) {
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/* We didn't find the TPM2 device. In this case, watch for it via udev. Let's create
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* an event loop and monitor first. */
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assert(!event);
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r = sd_event_default(&event);
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if (r < 0)
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return log_error_errno(r, "Failed to allocate event loop: %m");
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r = make_tpm2_device_monitor(event, &monitor);
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if (r < 0)
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return r;
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log_info("TPM2 device not present for unlocking %s, waiting for it to become available.", friendly);
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/* Let's immediately rescan in case the device appeared in the time we needed
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* to create and configure the monitor */
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continue;
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}
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for (;;) {
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/* Wait for one event, and then eat all subsequent events until there are no
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* further ones */
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r = sd_event_run(event, processed ? 0 : UINT64_MAX);
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if (r < 0)
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return log_error_errno(r, "Failed to run event loop: %m");
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if (r == 0)
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break;
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processed = true;
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}
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log_debug("Got one or more potentially relevant udev events, rescanning for TPM2...");
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}
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if (pass_volume_key)
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r = crypt_activate_by_volume_key(cd, name, decrypted_key, decrypted_key_size, flags);
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else {
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_cleanup_(erase_and_freep) char *base64_encoded = NULL;
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/* Before using this key as passphrase we base64 encode it, for compat with homed */
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r = base64mem(decrypted_key, decrypted_key_size, &base64_encoded);
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if (r < 0)
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return log_oom();
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r = crypt_activate_by_passphrase(cd, name, keyslot, base64_encoded, strlen(base64_encoded), flags);
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}
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if (r == -EPERM) {
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log_error_errno(r, "Failed to activate with TPM2 decrypted key. (Key incorrect?)");
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return -EAGAIN; /* log actual error, but return EAGAIN */
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}
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if (r < 0)
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return log_error_errno(r, "Failed to activate with TPM2 acquired key: %m");
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return 0;
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}
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static int attach_luks_or_plain_or_bitlk_by_key_data(
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struct crypt_device *cd,
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const char *name,
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@@ -1083,6 +1303,8 @@ static int attach_luks_or_plain_or_bitlk(
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crypt_get_volume_key_size(cd)*8,
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crypt_get_device_name(cd));
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if (arg_tpm2_device || arg_tpm2_device_auto)
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return attach_luks_or_plain_or_bitlk_by_tpm2(cd, name, key_file, key_data, key_data_size, until, flags, pass_volume_key);
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if (arg_fido2_device || arg_fido2_device_auto)
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return attach_luks_or_plain_or_bitlk_by_fido2(cd, name, key_file, key_data, key_data_size, until, flags, pass_volume_key);
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if (arg_pkcs11_uri || arg_pkcs11_uri_auto)
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@@ -1305,14 +1527,14 @@ static int run(int argc, char *argv[]) {
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/* When we were able to acquire multiple keys, let's always process them in this order:
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*
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* 1. A key acquired via PKCS#11 or FIDO2 token
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* 1. A key acquired via PKCS#11 or FIDO2 token, or TPM2 chip
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* 2. The discovered key: i.e. key_data + key_data_size
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* 3. The configured key: i.e. key_file + arg_keyfile_offset + arg_keyfile_size
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* 4. The empty password, in case arg_try_empty_password is set
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* 5. We enquire the user for a password
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*/
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if (!key_file && !key_data && !arg_pkcs11_uri && !arg_pkcs11_uri_auto && !arg_fido2_device && !arg_fido2_device_auto) {
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if (!key_file && !key_data && !arg_pkcs11_uri && !arg_pkcs11_uri_auto && !arg_fido2_device && !arg_fido2_device_auto && !arg_tpm2_device && !arg_tpm2_device_auto) {
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if (arg_try_empty_password) {
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/* Hmm, let's try an empty password now, but only once */
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@@ -1353,6 +1575,8 @@ static int run(int argc, char *argv[]) {
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arg_pkcs11_uri_auto = false;
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arg_fido2_device = mfree(arg_fido2_device);
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arg_fido2_device_auto = false;
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arg_tpm2_device = mfree(arg_tpm2_device);
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arg_tpm2_device_auto = false;
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}
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if (arg_tries != 0 && tries >= arg_tries)
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