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cryptsetup: automatically measure used keyslot and mechanism (i.e. fido2, tpm2, pkcs11) to an NvPCR

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Fixes: #29877
This commit is contained in:
Lennart Poettering
2025-11-02 21:14:35 +01:00
parent 8a6e77f1a8
commit e5a2e78665
6 changed files with 198 additions and 29 deletions
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src/cryptsetup/cryptsetup.c
+175 -27
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@@ -123,6 +123,7 @@ static char *arg_tpm2_pcrlock = NULL;
static usec_t arg_token_timeout_usec = 30*USEC_PER_SEC;
static unsigned arg_tpm2_measure_pcr = UINT_MAX; /* This and the following field is about measuring the unlocked volume key to the local TPM */
static char **arg_tpm2_measure_banks = NULL;
static char *arg_tpm2_measure_keyslot_nvpcr = NULL;
static char *arg_link_keyring = NULL;
static char *arg_link_key_type = NULL;
static char *arg_link_key_description = NULL;
@@ -138,6 +139,7 @@ STATIC_DESTRUCTOR_REGISTER(arg_fido2_rp_id, freep);
STATIC_DESTRUCTOR_REGISTER(arg_tpm2_device, freep);
STATIC_DESTRUCTOR_REGISTER(arg_tpm2_signature, freep);
STATIC_DESTRUCTOR_REGISTER(arg_tpm2_measure_banks, strv_freep);
STATIC_DESTRUCTOR_REGISTER(arg_tpm2_measure_keyslot_nvpcr, freep);
STATIC_DESTRUCTOR_REGISTER(arg_tpm2_pcrlock, freep);
STATIC_DESTRUCTOR_REGISTER(arg_link_keyring, freep);
STATIC_DESTRUCTOR_REGISTER(arg_link_key_type, freep);
@@ -555,6 +557,21 @@ static int parse_one_option(const char *option) {
log_error("Build lacks OpenSSL support, cannot measure to PCR banks, ignoring: %s", option);
#endif
} else if ((val = startswith(option, "tpm2-measure-keyslot-nvpcr="))) {
if (isempty(val)) {
arg_tpm2_measure_keyslot_nvpcr = mfree(arg_tpm2_measure_keyslot_nvpcr);
return 0;
}
if (!tpm2_nvpcr_name_is_valid(val)) {
log_warning("Invalid NvPCR name, ignoring: %s", option);
return 0;
}
if (free_and_strdup(&arg_tpm2_measure_keyslot_nvpcr, val) < 0)
return log_oom();
} else if ((val = startswith(option, "try-empty-password="))) {
r = parse_boolean(val);
@@ -1012,7 +1029,7 @@ static int measure_volume_key(
if (r < 0)
return r;
if (r == 0) {
log_debug("Kernel stub did not measure kernel image into the expected PCR, skipping userspace measurement, too.");
log_debug("Kernel stub did not measure kernel image into the expected PCR, skipping userspace volume key measurement, too.");
return 0;
}
@@ -1060,7 +1077,80 @@ static int measure_volume_key(
return 0;
#else
return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "TPM2 support disabled, not measuring.");
return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "TPM2 support disabled, not measuring volume key.");
#endif
}
static int measure_keyslot(
struct crypt_device *cd,
const char *name,
const char *mechanism,
int keyslot) {
int r;
assert(cd);
assert(name);
if (!arg_tpm2_measure_keyslot_nvpcr) {
log_debug("Not measuring unlock keyslot, deactivated.");
return 0;
}
r = efi_measured_uki(LOG_WARNING);
if (r < 0)
return r;
if (r == 0) {
log_debug("Kernel stub did not measure kernel image into the expected PCR, skipping userspace key slot measurement, too.");
return 0;
}
#if HAVE_TPM2
_cleanup_(tpm2_context_unrefp) Tpm2Context *c = NULL;
r = tpm2_context_new_or_warn(arg_tpm2_device, &c);
if (r < 0)
return r;
_cleanup_free_ char *escaped = NULL;
escaped = xescape(name, ":"); /* avoid ambiguity around ":" once we join things below */
if (!escaped)
return log_oom();
_cleanup_free_ char *k = NULL;
if (keyslot >= 0 && asprintf(&k, "%i", keyslot) < 0)
return log_oom();
_cleanup_free_ char *s = NULL;
s = strjoin("cryptsetup-keyslot:", escaped, ":", strempty(crypt_get_uuid(cd)), ":", strempty(mechanism), ":", strempty(k));
if (!s)
return log_oom();
r = tpm2_nvpcr_extend_bytes(c, /* session= */ NULL, arg_tpm2_measure_keyslot_nvpcr, &IOVEC_MAKE_STRING(s), /* secret= */ NULL, TPM2_EVENT_KEYSLOT, s);
if (r == -ENETDOWN) {
/* NvPCR is not initialized yet. Do so now. */
_cleanup_(iovec_done_erase) struct iovec anchor_secret = {};
r = tpm2_nvpcr_acquire_anchor_secret(&anchor_secret, /* sync_secondary= */ false);
if (r < 0)
return r;
r = tpm2_nvpcr_initialize(c, /* session= */ NULL, arg_tpm2_measure_keyslot_nvpcr, &anchor_secret);
if (r < 0)
return log_error_errno(r, "Failed to extend NvPCR index '%s' with anchor secret: %m", name);
r = tpm2_nvpcr_extend_bytes(c, /* session= */ NULL, arg_tpm2_measure_keyslot_nvpcr, &IOVEC_MAKE_STRING(s), /* secret= */ NULL, TPM2_EVENT_KEYSLOT, s);
}
if (r < 0)
return log_error_errno(r, "Could not extend NvPCR: %m");
log_struct(LOG_INFO,
"MESSAGE_ID=" SD_MESSAGE_TPM_NVPCR_EXTEND_STR,
LOG_MESSAGE("Successfully extended NvPCR index '%s' with '%s'.", arg_tpm2_measure_keyslot_nvpcr, s),
"MEASURING=%s", s,
"NVPCR=%s", arg_tpm2_measure_keyslot_nvpcr);
return 0;
#else
return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "TPM2 support disabled, not measuring keyslot.");
#endif
}
@@ -1074,6 +1164,8 @@ static int log_external_activation(int r, const char *volume) {
static int measured_crypt_activate_by_volume_key(
struct crypt_device *cd,
const char *name,
const char *mechanism,
int keyslot,
const void *volume_key,
size_t volume_key_size,
uint32_t flags) {
@@ -1091,18 +1183,19 @@ static int measured_crypt_activate_by_volume_key(
if (r < 0)
return r;
if (volume_key_size == 0) {
if (volume_key_size > 0)
(void) measure_volume_key(cd, name, volume_key, volume_key_size); /* OK if fails */
else
log_debug("Not measuring volume key, none specified.");
return r;
}
(void) measure_volume_key(cd, name, volume_key, volume_key_size); /* OK if fails */
(void) measure_keyslot(cd, name, mechanism, keyslot); /* ditto */
return r;
}
static int measured_crypt_activate_by_passphrase(
struct crypt_device *cd,
const char *name,
const char *mechanism,
int keyslot,
const char *passphrase,
size_t passphrase_size,
@@ -1136,17 +1229,21 @@ static int measured_crypt_activate_by_passphrase(
if (!vk)
return -ENOMEM;
r = crypt_volume_key_get(cd, keyslot, vk, &vks, passphrase, passphrase_size);
if (r < 0)
return r;
keyslot = crypt_volume_key_get(cd, keyslot, vk, &vks, passphrase, passphrase_size);
if (keyslot < 0)
return keyslot;
return measured_crypt_activate_by_volume_key(cd, name, vk, vks, flags);
return measured_crypt_activate_by_volume_key(cd, mechanism, name, keyslot, vk, vks, flags);
shortcut:
r = crypt_activate_by_passphrase(cd, name, keyslot, passphrase, passphrase_size, flags);
if (r == -EEXIST) /* volume is already active */
return log_external_activation(r, name);
return r;
keyslot = crypt_activate_by_passphrase(cd, name, keyslot, passphrase, passphrase_size, flags);
if (keyslot == -EEXIST) /* volume is already active */
return log_external_activation(keyslot, name);
if (keyslot < 0)
return keyslot;
(void) measure_keyslot(cd, name, mechanism, keyslot);
return keyslot;
}
static int attach_tcrypt(
@@ -1226,7 +1323,14 @@ static int attach_tcrypt(
return log_error_errno(r, "Failed to load tcrypt superblock on device %s: %m", crypt_get_device_name(cd));
}
r = measured_crypt_activate_by_volume_key(cd, name, NULL, 0, flags);
r = measured_crypt_activate_by_volume_key(
cd,
name,
/* mechanism= */ NULL,
/* keyslot= */ -1,
/* volume_key= */ NULL,
/* volume_key_size= */ 0,
flags);
if (r < 0)
return log_error_errno(r, "Failed to activate tcrypt device %s: %m", crypt_get_device_name(cd));
@@ -1351,6 +1455,8 @@ static bool use_token_plugins(void) {
* plugins, if measurement has been requested. */
if (arg_tpm2_measure_pcr != UINT_MAX)
return false;
if (arg_tpm2_measure_keyslot_nvpcr)
return false;
#endif
/* Disable tokens if we're in FIDO2 mode with manual parameters. */
@@ -1586,7 +1692,14 @@ static int attach_luks_or_plain_or_bitlk_by_fido2(
}
if (pass_volume_key)
r = measured_crypt_activate_by_volume_key(cd, name, decrypted_key, decrypted_key_size, flags);
r = measured_crypt_activate_by_volume_key(
cd,
name,
"fido2",
/* keyslot= */ -1,
decrypted_key,
decrypted_key_size,
flags);
else {
_cleanup_(erase_and_freep) char *base64_encoded = NULL;
ssize_t base64_encoded_size;
@@ -1597,7 +1710,14 @@ static int attach_luks_or_plain_or_bitlk_by_fido2(
if (base64_encoded_size < 0)
return log_oom();
r = measured_crypt_activate_by_passphrase(cd, name, keyslot, base64_encoded, base64_encoded_size, flags);
r = measured_crypt_activate_by_passphrase(
cd,
name,
"fido2",
keyslot,
base64_encoded,
base64_encoded_size,
flags);
}
if (r == -EPERM) {
log_error_errno(r, "Failed to activate with FIDO2 decrypted key. (Key incorrect?)");
@@ -1743,7 +1863,14 @@ static int attach_luks_or_plain_or_bitlk_by_pkcs11(
assert(decrypted_key);
if (pass_volume_key)
r = measured_crypt_activate_by_volume_key(cd, name, decrypted_key, decrypted_key_size, flags);
r = measured_crypt_activate_by_volume_key(
cd,
name,
"pkcs11",
/* keyslot= */ -1,
decrypted_key,
decrypted_key_size,
flags);
else {
_cleanup_(erase_and_freep) char *base64_encoded = NULL;
ssize_t base64_encoded_size;
@@ -1760,7 +1887,14 @@ static int attach_luks_or_plain_or_bitlk_by_pkcs11(
if (base64_encoded_size < 0)
return log_oom();
r = measured_crypt_activate_by_passphrase(cd, name, keyslot, base64_encoded, base64_encoded_size, flags);
r = measured_crypt_activate_by_passphrase(
cd,
name,
"pkcs11",
keyslot,
base64_encoded,
base64_encoded_size,
flags);
}
if (r == -EPERM) {
log_error_errno(r, "Failed to activate with PKCS#11 decrypted key. (Key incorrect?)");
@@ -2048,7 +2182,14 @@ static int attach_luks_or_plain_or_bitlk_by_tpm2(
}
if (pass_volume_key)
r = measured_crypt_activate_by_volume_key(cd, name, decrypted_key.iov_base, decrypted_key.iov_len, flags);
r = measured_crypt_activate_by_volume_key(
cd,
name,
"tpm2",
/* keyslot= */ -1,
decrypted_key.iov_base,
decrypted_key.iov_len,
flags);
else {
_cleanup_(erase_and_freep) char *base64_encoded = NULL;
ssize_t base64_encoded_size;
@@ -2059,7 +2200,14 @@ static int attach_luks_or_plain_or_bitlk_by_tpm2(
if (base64_encoded_size < 0)
return log_oom();
r = measured_crypt_activate_by_passphrase(cd, name, keyslot, base64_encoded, base64_encoded_size, flags);
r = measured_crypt_activate_by_passphrase(
cd,
name,
"tpm2",
keyslot,
base64_encoded,
base64_encoded_size,
flags);
}
if (r == -EPERM) {
log_error_errno(r, "Failed to activate with TPM2 decrypted key. (Key incorrect?)");
@@ -2085,9 +2233,9 @@ static int attach_luks_or_plain_or_bitlk_by_key_data(
assert(key_data);
if (pass_volume_key)
r = measured_crypt_activate_by_volume_key(cd, name, key_data->iov_base, key_data->iov_len, flags);
r = measured_crypt_activate_by_volume_key(cd, name, /* mechanism= */ NULL, /* keyslot= */ -1, key_data->iov_base, key_data->iov_len, flags);
else
r = measured_crypt_activate_by_passphrase(cd, name, arg_key_slot, key_data->iov_base, key_data->iov_len, flags);
r = measured_crypt_activate_by_passphrase(cd, name, /* mechanism= */ NULL, arg_key_slot, key_data->iov_base, key_data->iov_len, flags);
if (r == -EPERM) {
log_error_errno(r, "Failed to activate. (Key incorrect?)");
return -EAGAIN; /* Log actual error, but return EAGAIN */
@@ -2138,9 +2286,9 @@ static int attach_luks_or_plain_or_bitlk_by_key_file(
return log_error_errno(r, "Failed to read key file '%s': %m", key_file);
if (pass_volume_key)
r = measured_crypt_activate_by_volume_key(cd, name, kfdata, kfsize, flags);
r = measured_crypt_activate_by_volume_key(cd, name, /* mechanism= */ NULL, /* keyslot= */ -1, kfdata, kfsize, flags);
else
r = measured_crypt_activate_by_passphrase(cd, name, arg_key_slot, kfdata, kfsize, flags);
r = measured_crypt_activate_by_passphrase(cd, name, /* mechanism= */ NULL, arg_key_slot, kfdata, kfsize, flags);
if (r == -EPERM) {
log_error_errno(r, "Failed to activate with key file '%s'. (Key data incorrect?)", key_file);
return -EAGAIN; /* Log actual error, but return EAGAIN */
@@ -2166,9 +2314,9 @@ static int attach_luks_or_plain_or_bitlk_by_passphrase(
r = -EINVAL;
STRV_FOREACH(p, passwords) {
if (pass_volume_key)
r = measured_crypt_activate_by_volume_key(cd, name, *p, arg_key_size, flags);
r = measured_crypt_activate_by_volume_key(cd, name, /* mechanism= */ NULL, /* keyslot= */ -1, *p, arg_key_size, flags);
else
r = measured_crypt_activate_by_passphrase(cd, name, arg_key_slot, *p, strlen(*p), flags);
r = measured_crypt_activate_by_passphrase(cd, name, /* mechanism= */ NULL, arg_key_slot, *p, strlen(*p), flags);
if (r >= 0)
break;
}